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IMBSIR 81-2348

Materials for Instrumentation for

Fossil Energy Technologies

(A Review and Program Plan of R&D Needs Conducted by the

National Bureau of Standards)

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington, DC 20234

August 1 981

-QC

100

.056

81-2348

1981

Prepared for Department of Energy

Washington, DC 20545

NBSIR 81-2348

MATERIALS FOR INSTRUMENTATION FOR

FOSSIL ENERGY TECHNOLOGIES

(A Review and Program of R&D Needs Conducted by the

National Bureau of Standards)

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OCT 1 4 1981

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H.P.R. Frederikse and P.K. Schenck*

G.W. Burns**

R.R. Oils and J.R. Whetstone***

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Center for Materials Science*

Center for Absolute Physical Quantities**

Center for Chemical Engineering***

Washington, DC 20234

August 1 981

Prepared for Department of Energy

Washington, DC 20545

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS. Ernest Ambler, Director

CO

MATERIALS FOR INSTRUMENTATION FOR FOSSIL ENERGY TECHNOLOGIES

A Review and Program Plan of R&D Needs

Conducted by the National Bureau of Standards

for

The Department of Energy - Fossil Energy (AR&TD)

under contract No. EA-77-A-01-6010

Task No. A002-MER

by

the National Bureau of Standards

Washington, DC 20234

August 1981

H. P. R. Frederikse and P. K. Schenck

Center for Materials Science

G. W. Burns

Center for Absolute Physical Quantities

R. R. Oils and J. R. Whetstone

Center for Chemical Engineering

"This report was prepared for the internal use by the National Bureau of

Standards and the Department of Energy as a planning document. Neither

the United States nor the U.S. Department of Energy and the National Bureau

of Standards, nor any of their employees, nor any of their contractors,

subcontractors , or their employees, makes any warranty, expressed or implied,

or assumes any legal liability or responsibi 1 i ty for the accuracy, completeness,

or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights".
TABLE OF CONTENTS

EXECUTIVE SUMMARY

ACKNOWLEDGEMENTS

CHAPTER 1 . Introducti on 1 1.1 Objectives 1

1 . 2 Approach 2

1 .3 Scope 3

1.4 Present Activities 4

CHAPTER 2. Measurement Needs & Materials Requirements 7 2.1 Process Parameters 7 a. Multi-component Flow 7 b. Pressure 9

c. Temperature 9

d. Composition - Chemical 14

e. Composition - Phases, Particulates 15

f. Composition - Emissions 16

2.2 Erosion and Hot Corrosion 17

2.3 Fuel Characterization 18

2.4 Instrumentation for Thermal & Mechanical Properties . . 21

2.5 Testing Procedures and Facilities 24

2.6 Data Centers 26

CHAPTER 3. Suggested Program Plan 28

3.1 General Considerations 28

3.2 Rationale and Recommendations 29

3.3 Level of Effort 29

3.4 Coordination and Implementation 34

3.5 Recommended Projects 37

REFERENCES 75

APPENDICES

I. Review of Major Fossil Energy Processes

II. Present Activities in the Area of Materials/Instrumentation for Fossil Energy

III. Case Studies

a. Flow Measurement Research for Coal Slurry Flows - J. R. Whetstone

b. Acoustic Char-Flow Monitors for the BI-GAS Pilot Plant - T. P. Mulcahey

c. Temperature Measurement in Coal Gasifiers - G. W. Burns

d. High Temperature Gas Turbine Erosion/Corrosion Thin Film

Sensors and Related Devices - R. R. Dils

e. Analysis by High Pressure Sampling Mass Spectrometry - P. K. Schenck

f. Measurement of Heat Conductivity - H. P. R. Frederikse

IV. Miniworkshop

Distribution List
1

Executive Summary

This report is an assessment of the materials research needed to

address the instrumentation problems in the various Fossil Energy

Technologies. The study was conducted by the National Bureau of Standards

on request of the Department of Energy (Fossil Energy Program).

Reliable operation of Fossil Energy plants requires knowledge, and

hence measurement, of essential parameters like temperature, flow, heat

transfer, liquid and gas composition, etc. Furthermore it is essential

to sample and/or monitor possible erosion, hot corrosion, and mechanical

degradation of plant components. The equipment needed for these measurements must be able to operate under extremely harsh conditions, and

consequently, the selection of proper materials is a major problem. The

main theme of this report is that the problems of accurate measurements

and reliable materials are intimately connected and that the design of

instrumentation in the field of Fossil Energy should go hand-in-hand

with carefully planned materials research.

The review of research needs in this area has lead to a suggested

Program Plan presented at the end of this report. Possible avenues of

approach are discussed. Priorities and levels of effort are indicated.

(See Tables 1, 2 and 3 on pages 31-34).

As the title of this report indicates the research is aimed at

"Materials for Instrumentation". In some of the recommended work the

emphasis is somewhat more on the materials aspect, while in other cases

the measurement angle receives at bit more attention.

The plan divides the proposed research in 38 projects covering 4

major research areas:

I. Materials Research for Sensors

A. Erosion/Hot Corrosion: slurries, particulates in gas, erosion/

corrosion sensors.

B. Thermal /Mechanical Properties: heat transfer, thermal expansion,

heat capacity, mechanical strength, NDE for cracks and voids, etc.

C. Materials Problems in Process Parameter Measurement: flow,

temperature, pressure, composition, coatings, adhesion, electrochemical

cells, windows and spool pieces.

II. Fuel Characterization: chemistry and physics of coal, flyash
1

1

III. Testing and Data: test methodology, test facilities for liquids,

slurries and gas streams, test rigs for combustion, erosion/corrosion

;

data banks on materials and instrumentation

IV. Exploratory Research: new ideas in materials for measuring equipmentIt is felt that the above listing expresses the order of importance of

the research areas under consideration. Yet, even a minimum program should

contain some elements of areas II, III and IV.

The authors of this report realize that a considerable amount of materials

research is being performed which is relevant to the problems of Fossil Energy

Instrumentation. However, the connection is not always obvious. Much of the

work is either aimed at solving some particular, immediate problem in coal

conversion plants, or the research is general and basic in nature and does

not apply to the specific Fossil Energy needs. The goal of the present program

recommendations is to conduct applied research focussed on generic materials

problems related to instrumentation in coal conversion or coal combustion

facilities.

The report does not devote much space to an expose of the instrumentation

requirements as such. These needs have been listed and analyzed systematically

in a number of reports to the Department of Energy, [e.g., Technical

Memoranda 1-10, Argonne National Laboratory (refs. 6 and 7) and the series

of Proceedings of I&C Symposia (ref. 5, p. 84)].

Detailed discussions of half a dozen selected problems (Case Studies)

have been collected in Appendix III.
m

Acknowledgements

The authors want to thank a number of colleagues for their help

and cooperation in putting together this report. The Instrumentation

and Control Group at Argonne National Laboratory (especially Nancy O' Fallon,

Paul Raptis and Tom Mulcahey) has given valuable assistance in familiarizing

us with the field of Instrumentation for Fossil Energy. Special thanks are due to our colleagues at NBS; to Sam Schneider, Taki Negas and Ken Kreider

for critical reading of the manuscript, and to Greg Rosasco, Jim Schooley

and John Hastie for important information in the areas of temperature

measurement and gas analysis, respectively

.

Discussions with experts at several research laboratories , pilot

plants, as well as at trade and professional organizations have provided

important input to this report: Bob Eustis, Sidney Self and their

colleagues at the Gas Dynamics Laboratory of Stanford University,

J. R. Hightower and others of Oak Ridge National Laboratory, several

engineers at the SRC-II pilot plant in Ft. Lewis, Washington (Dennis Canfield,

et al.), John Walsh (JPL) and various members of SCIEP (Society for Control

and Instrumentation of Energy Processes), as well as Bob Jaffee (among

others) at EPRI. Special thanks are due to W. M. Roquemore of the Aero

Propulsion Laboratory of the Air Force, who provided valuable comments on the report, especially in the area of optical instrumentation.

Valuable assistance was received from the participants in a one-day

^discussion. of the report's recommendations, which was hel^ immediately after . its completion in June 1981 [Appendix IV).
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CHAPTER 1 . Introduction

1 . 1 Objectives

In late spring of 1980 the National Bureau of Standards was approached

by representatives of the AR&TD-branch of the Department of Energy (Fossil

Energy) with a request to review the needs for research on Materials as related

to Instrumentation in Fossil Energy Facilities and to make recommendations with

respect to appropriate Research and Development activities in this area. The Department of Energy, together with a sizable number of private

corporations , is deeply involved in a variety of programs to develop

and expand several new Fossil Energy processes from the laboratory through

the test-, pilot- and demonstration stages to full commercial application.

At each of these stages, in nearly every component of the system, there is a great need for measuring certain control parameters and product properties.

This in turn means development of instrumentation and selection of appropriate

materials for the measuring equipment that can withstand the harsh environments

in fossil energy systems.

At the same time the designers of fossil energy conversion facilities

and power plants need reliable data on material properties under hitherto

unexplored conditions of temperature, pressure or chemical attack. The

novel approaches employed in the fossil energy field dictate the use of some

new compounds and substances (e.g., special coatings, composites), and

therefore the development of improved or redesigned equipment for the

determination of material characteristics in extreme environments. The

above discussion can be summarized as follows: Better measurements require

better materials, and new materials need new measurement techniques. In

contrast to the prevailing view that the measurement equipment and the

construction materials required in these technologies can be taken "off-the-shelf"

it is becoming increasingly clear that both these ingredients require new approaches and advanced research efforts.

The objective of this study is to review the needs for materials

research as related to the development of instrumentation for Fossil

Energy, and to outline an appropriate program to satisfy these needs.

The work is divided into several Tasks:

a. The study will assess the requirements for instrumentation to

measure and record essential process and product parameters (such as
2

temperature, pressure, flow and mechanical properties) and indicate the

materials development necessary for the design and operation of such

i nstrumentation.

b. The study will review the measuring capabilities with respect to

the chemical and structural analysis of both active and passive substances

(gas, liquid and solids) in fossil energy facilities.

c. The study will pinpoint the needs for new and modified techniques

to obtain the materials data that are essential for the proper performance'

and design of facility components.

d. These reviews and assessments will be the basis of a suggested R&D

program on "materials for instrumentation in fossil energy" with indications

of priorities and staffing levels.

1.2 Approach . In order to perform these tasks, NBS formed a group of 5

scientists and engineers with thorough knowledge in various aspects of

materials science, fluid mechanics, temperature and pressure control

and chemical analysis. The group gathered information from many

different sources involved in Fossil Energy development, discussed and

analyzed the difficulties in presently used instrumentation and materials,

and suggested possible avenues of research that can lead to modifications

or alternatives in measuring techniques and material usage. Some of these

suggestions are of an engineering nature, others are more basic-scienceoriented. In some cases the recommendations are very specific and oriented

towards one problem in one particular process. In other cases, the

suggested research effort is broad and generic and addresses several

problems encountered in a number of technologies not necessarily limited

to the Fossil Energy field.

The report is organized as follows: This introduction (Chapter 1)

indicates the objectives and scope of the review and touches on the approach

being taken and the present activities in the area of measurement and related

materials needs.

Chapter 2 reviews the Materials and Instrumentation problems and briefly

discusses promising areas of research and development. Chapter 3 contains

the actual Program Plan listing the various areas that require attention.

A few general remarks about implementation have been added.
3

Additional information is presented in three Appendices. Appendix I briefly describes the major Fossil Energy Technologies. Two tables indicating

present research and development work in the instrumentation/materials field are tabulated in Appendix II. A number of specific examples have been chosen for

an in-depth discussion of the technical aspects, in order to illustrate the

close relationship between measurement, materials and design. These 6 Case

Studies have been collected in Appendix III.

1 . 3 Scope

The Program of the Fossil Energy Administration can be divided in

3 major categories: Coal, Petroleum and Gas. Because the main goal of

these programs is to diminish the nation's dependence on oil and gas,

it is logical that the emphasis is on coal conversion. At the same time,

it should be kept in mind that the potential resources in oil shale

are enormous; most recently there are indications that interest in oil

shale exploitation is again increasing. In addition, more attention is

being focussed on enhanced oil recovery schemes.

Over the last few years the administrative organization of the

various Fossil Energy Programs within the Department of Energy has

crystallized to some extent. Besides branches dealing with mining and

preparation, gasification and liquefaction, there are departments concerned

with direct combustion, gas turbines, MHD, fuel cells, in-situ gasification,

environmental control, as well as a division devoted to Advanced Research

and Technology.

The absolute financial support for each of these activities has fluctuated

considerably over the years, and even the relative ranking of these technologies

is difficult to assess, especially at this particular point in time. May 1981.

It is obvious, therefore, that planning for research and development

is a difficult task. As a result, planners, engineers and scientists try

to find shortcuts, trying to show that this or that approach will work. In

the process they seem to overlook the fact that they do not possess the

necessary information on process conditions or the required design data to

guarantee successful operation. Needed as an adjunct to present efforts

Is a research and development program - especially with respect to materials

and instrumentation - that is somewhat more oriented towards long range benefits.

Such a program has to be geared to the severe environment in most components

of Fossil Energy facilities. Brief descriptions of some of the major

processes and the physical and chemical conditions existing in these

systems are presented in Appendix I.
4

Considering the harsh atmospheres one has to deal with, it is not

realistic to expect complete solutions overnight. A somewhat more basic

and long range approach has definite advantages. This ties in with the

atmosphere of uncertainty described above. A considerable number of problems

in fossil energy plants and test rigs are caused by high temperatures and

pressures, erosion and corrosion, and by the complexity of the process

fluids and gases. These problems often require the use of new or modified

materials, and improved or novel measurement techniques. Although the problems

are specific, in many cases the needed research is generic, and the solution

can be applied in several technologies. For instance, the question of how to

control chemical attack by molten slag is not limited to MHD, but appears in

similar ways in the operation of slagging gasifiers and coal combustors.

This report is focused on the materials-for-instrumentation problems

encountered in gasification, liquefaction, direct combustion and gas turbines.

Very little will be said about the other Fossil Energy technologies for a number of different reasons.

1 .4 Present Activities (in Materials and Instrumentation for

Fossil Energy Processes ) Instrumentation for fossil energy has begun to receive some attention

in the last 4 or 5 years. Most of the development work is aimed at the

solution of special measurement problems that arise in particular subsections

of coal conversion facilities.

The same can be said for materials research. The corrosion rates of

various metals and alloys are being compared by means of test runs on representati ve coupons in a "standard gasification environment".^^* Certain

mechanical tests are being performed on liner refractories in "typical

gasifier atmospheres".^^ There is, however, very little systematic research

of a generic nature, aimed at understanding the degradation process and

solving the problem by proper material selection or modification.

Most of the materials and instrumentation development work is shortrange in nature: the conventional measuring equipment is being modified to

fit the more strenuous plant conditions. A material is replaced on the

basis of the very scant data of its behavior at the high temperature

and/or high pressure of the coal plant component. One often overlooks

that the presence of small amounts of water, hydrogen, sulfur or particular

*The references for the main body of the report are listed on pages 75-77.
5

metals (e.g., Ti), radically changes the durability of the material and

hence the service life of the instrument. The result of this attitude

2 was well -stated in a recent DoE report:

"Coal conversion process development units (PDU's) and

pilot plants have repeatedly experienced disproportionate

problems with components compared with apparently similar

applications in industry. This poor record has been

attributed to the philosophy that PDU's and pilot plants are intended primarily to validate process chemistry, with

limited consideration given to reliability. Frequently,

pilot plant construction does not reflect the best or even reasonable materials selection for commercial plants "

What is needed is better contact and cooperation between workers in the field,

including plant engineers, instrument manufacturers and laboratory researchers.

Of course, continuity of effort in this area is of prime importance.

We do not want to leave the reader with the impression that the amount of

materials research pertinent to the Fossil Energy field is negligible. However,

the connection between this research and the materials problems in coal technologies is not always realized. Many R&D organizations are involved in basic investigations of material properties in severe environments sponsored not only by the

Department of Energy, but also by the Department of Defense, the National Science

Foundation, NASA and many other government or private funding institutions. A

list of some of the laboratories that are active in these areas is presented in

Table a. of Appendix II.

In this connection we should mention the activities of the Energy Materials

Coordinating Committee (EMCC). This committee was set up to exchange information

and to promote materials research within the Department of Energv. Its annual

3

report summarizes the materials research projects supported by the Department,

Including those of the major programs ^Nuclear, Fossil, Solar, Conservation, etc.)

and of the Office of Energy Research. An appreciable number of these projects

deal with problems that are relevant - but not necessarily specific - to the

subject of this report. Materials for Instrumentation in Fossil Energy.

The word "materials" has a broad meaning as used in the present report;

it includes materials for meters and sensors, construction materials, as well

as process solids and fluids such as coal char, coal slurries, coal slag and

kerogen.

In the area of instrumentation there has been an interesting development

in 198Q, namely the establishment of an organization that aims to be a forum

for the exchange of ideas in the many areas of fossil energy where better
6

measurement equipment is urgently needed. This group, the Society for Control

and Instrumentation of Energy Processes (SCIEP), is still in its infancy but is

growing rapidly. It now is one of the co-sponsors of the Annual Symposium on Instrumentation and Control for Fossil Energy Processes together with the

Department of Energy and Argonne National Laboratory. Nearly a dozen subgroups

4 have been organized and many of these groups have held very useful workshops

during 1980 (see Appendix Il-b).
7

CHAPTER 2. Measurement Needs and Materials Requirements

5 2.1. Process Parameters

a. Multi -component Flow

One of the most crucial measurements in nearly all Fossil Energy Processes

is the determination of the rate of flow of solids, liquids and gases, separate

and mixed with each other. This measurement is difficult experimental ly because

of the need to detect the concentration and the flow velocity of each component.

Another reason is the very aggressive environment which produces uncertainties

in the metering device and degradation of the equipment being used. At the same time, intelligent design of flowmeters and interpretation of their response

is hampered by the lack of fundamental understanding and mathematical description

of_two-_and three-phase flow. (See Case Study~a^'- Appendix IIIJT

One can divide flowmeters in two categories: intrusive and nonintrusive.

The former is often abandoned in favor of the latter because many designers and

operators believe that by switching to a nonintrusive flowmeter, materials

problems can be avoided. This is not always true, because the latter type may

depend on the proper material and design of special windows or wall sections.

The kind of flowmeter that can be employed is dictated mostly by the

prevailing process parameters (temperature, pressure, chemical environment, etc.),

and by the physical characteristics of the process material. A rather complete

list of flow metering devices includes more than two dozen different types of

6 * which some 6 to 10 are still under development. Among the intrusive flowmeters

the orifice plate and the Venturi type flow sensors are the most popular. These

two can be used both with gas and liquid and both are being tried for multi

component flows, but fail to provide an accurate measurement.

An acoustic device for determining the presense or absence of the flow

of char Citixed with steam) entering a gasifier reactor is being developed

at ANL (Case Study b).

Several new nonintrusive flowmeters are commercially available or under

development. An example is the ultrasonic flow sensor, based on a time-delay

effect.^ A number of these devices are available for use at or just above

room temperature. Although some encouraging results have been reported^

*In the present report, we will often refer to this "Overview of Coal Conversion

Process Instrumentation". It is a compact review of the major commercial

instruments that can be used, in principle, to measure the following parameters: flow, temperature, level, pressure, composition, viscosity and heat

content.
8

when used to measure high temperature slurries, a considerable amount of

development work will have to be done before a reasonably-priced, reliable,

instrument for this regime will have reached full commercialization.

Other non-intrusi ve flowmeters that need considerable R&D efforts are

o the tracing types (e.g., pulsed neutron activation ), meters based on capacitance or thermal mass flow, and devices that use laser light scattered

by small particles in the stream (Doppler shifted). The latter method is

particularly interesting for dilute, high temperature, particle-laden gas

streams because one can measure not only the flow velocity but also obtain

information about the gas temperature and the size and size distribution of

1 fi ??

the particles (see below). ’ All these non-intrusi ve methods depend on the

capability of injecting the radiation (or neutrons) into the flow and of

detection of the reflected or transmitted signal inside or outside the pipe,

tube or chamber. Hence, a window, pipe segment or spool piece sufficiently

transparent to the radiation or particles is required. In most cases this

"window problem" can be solved by using a temperature and chemically

resistant ceramic or metallic disc a short distance away in a side arm

of the main pipe or reactor. This side arm' is purged regularly either

mechanically or by a flowing gas.

Materials research is needed to determine the appropriate "window" or

spool piece material for particular applications in various severe environments.

In general the two most important factors that lead to degradation of

intrusive flowmeters are erosion and corrosion. Orifice plates could be used

for high temperature slurries if the material of the plate (and the shape

of the orifice) were designed to withstand the enormous erosion caused by

the solid particles in the liquid. Similar considerations hold for

this kind of flowmeter in high temperature gas streams containing

particulates. In many cases erosion is accompanied by corrosion and

the combined effect is even more disastrous. The result of either or both effects is rapid deterioration of the orifice and a deviation from

the true calibration often in a matter of hours.

Of course, other flowmeters also are subject to this erosion/corrosion

damage: again, any significant change in the dimensions of the critical

component of the device produces unacceptable variations in the calibration.
9

b. Pressure^

Fossil energy facilities require a variety of reliable pressure measurements in several stages of the processes. In some applications, quick

response is of prime importance as a sudden pressure change may be a precursor

to explosion or fire. When pressure instrumentation is used for process

control, long term repeatabi 1 ity and stability is the main concern. In the case where pressure measurement is aimed at materials accountability, then

accuracy is most important.

Piezoelectric pressure sensors have the fastest response time... on the order of microseconds. Certain crystals without a center of symmetry

produce a surface potential difference when they are stressed in appropriate

directions which can be used to indicate a change of pressure. Quartz,

Rochelle salt, barium-titanate and lead-zirconate-titanate all exhibit

usable piezoelectricity. There is a need for improved piezoelectric

materials having greater signal output, less sensitivity to temperature

and light, and better repeatability within a given unit and from lot to lot.

Pressure control instrumentation normally involves monitoring the

mechanical distortion of some elastic element such as a spiral tube,

bellows, capsule, or diaphragm. Many varied schemes are used to convert

these distortions into controlling electrical signals. Response times for

such equipment are on the order of milliseconds. The principal materials

problems in these sensors can be remedied by developing elastic element

materials with lower mechanical hysterisis, greater resistance to chemical

attack, and above all, greater high temperature durability.

Very slow response times are generally adequate when pressure measurements

are used for materials accountability. As these measurements are normally

done in a benign environment, currently available instrumentation is usually

acceptable.

Overall, the greatest need is to develop materials for pressure sensors

in high temperature environments. There is a great dearth of instrumentation

for application above 200 ®C.

c- Temperature^

The determination of the temperature is one of the most essential measurements

to be made in all energy technologies. In fossil energy processes the range is

very large, extending up to 2500 °C in MHD combustors. In general the measurement

of the temperature, be it by means of thermometers, pyrometers or other
10

temperature sensors, is severely hampered by the harsh environment encountered

in coal conversion facilities. Just as with other measuring devices (for flow,

pressure composition, etc) the intrusive instruments (such as thermocouples) are subject to very high temperatures and pressures, extraordinary reactive

atmospheres, as well as highly erosive particulate streams.

The available temperature sensors can be divided in 2 classes:

1. contact thermometers and 2. non-contact thermometers . Class 1 can

be subdivided in about 5 categories: First of all, there are thermocouple

thermometers , which are probably the most generally used type of temperature

sensor, due to their simplicity, versatility, and general reliability. As

measuring instruments, they are found as devices that are simply constructed

at almost no cost, or as expensive devices constructed with painstaking care. Their thermoelements consist of metals or alloys used in a variety of

configurations, typically as wires, ribbons, rods, tubing, or as vapor-deposited

thin films.

While approximately three hundred different types of temperature measuring

thermocouples have been identified and studied, only a few types, having the

more favorable characteristics, are in general use. These favorable types

9 include, Cu and Fe-constantans used to 760 °C, Chromel/Alumel couples used

to 1200 ®C, several types comprised of Pt and Pt-Rh alloys used to 1750 °C,

and several W-Re types that extend the range up to above 2800 °C (5570 °F).

There are also special alloy combinations, such as Ni-9% Or and Au-0.07 at % Fe,

available for use at very low temperatures, down to 1 K. For the reliable use and performance of thermocouples, it is essential

that the thermocouple materials be protected from contamination caused by the

environment in which they are employed by selecting and using the proper materials

for their insulation and protection. In harsh chemical environments at elevated

temperatures, the thermocouple wires are often insulated by a metal oxide and

shielded by a metal tube that is placed within a primary thermowell which in turn

is inserted directly into the process environment. Of course, when the protection

gets heavier, the time response becomes longer. Consequently, it is important

to select the strongest and lightest material for the primary thermowell. Much

research can and should be done to improve the material choices for thermocouple

protection, both in general environmental regimes and for specific applications

(see Case Study c).
n

other contact thermometers are based on physical properties such as electrical resistance, thermal expansion, sound velocity, and viscosity. One

kind of resistance thermometer is based on the temperature dependence of the

resistance of metals, such at Pt or Ni. These devices cover a wide temperature

range from -250 to 1000 °C. Their advantage is that they can be made small and

therefore respond very quickly. Such sensors can be made in the form of thin

films and hence can be deposited exactly at the spot on the surface where

the temperature reading is desired. They can be protected by the most

desirable insulators. Research needs to be conducted in determining how

these metallic sensors are degraded by impurities from the insulating

material, and the results should determine the appropriate insulator to

be used.

A different type of resistance thermometer is the thermistor, a ceramic

semiconductor, available as beads, bead-in-glass probes, rods, discs, flakes,

etc. They are composed primarily of Mn and Ni oxides, with dopants of Cu-,

Co-, Fe-, or other metal oxide. The oxide mixture is normally sintered at

about 1200 °C and the devices are useful thermometers over the temperature

range 1 K to 1100 K. Because these oxides are semiconductors, the temperature

coefficient of resistance is unusually large. Again, these oxides can be

produced as thin films and thus make a small, fast temperature device. The

stability of thermistors at high temperatures has not been investigated.

The use of both kinds of resistance thermometers can be advanced by a combination of basic thermometry studies, proper materials selection and

a wide ranging testing program.

The ultrasonic thermometer is based on the temperature dependence of

5a

the velocity of sound in a solid rod . This velocity is derived from the

measured time interval between reflections of a sound pulse from the end

surface and from a "neck" in the rod. The time delay of this sound pulse is

measured by a transducer. The use of this thermometer is limited by the maximum

temperature and the environment which the transducer is able to endure.

The bi-metallic strip operates on the principle of differential

expansion between two different metals bound together at one end. When

heated, the strip will bend and hence be used as a temperature indicator.

Unfortunately, the range is limited and the displacement is non-linear.
12

More promising is the fluidic thermometer based on the temperature

dependence of the viscosity of a gas flowing through a capillary. This thermometer

has considerable possibilities when the use of thermocouples becomes very

difficult: contact with aggressive molten substances (such as iron or slag),

and cases in which the thermometer has to operate in electric or electromagnetic

fields, or in strongly reactive atmospheres (e.g., O

2

, H

2

, Application of

the fluidic thermometer in fossil energy experiments and pilot plants requires

further studies and tests of materials appropriate for each particular need.

Recent years have seen an increased interest in non-contact thermometers , especially for use at very high temperature, in strongly corrosive and

erosive environments and in cases where immediate response is mandatory.

The radiation pyrometer (spectral or total) has been used for a long time.

However, these instruments are not without difficulties. One of the problems is

the uncertainty of the exact location where the temperature is being measured,

especially when the optical path is transversed by a stream of gases, particulates

or droplets. Other difficulties are the accuracy (often photometrical ly limited

in field applications) of the measurement and the emissivity of the surface and

gases being observed. Although two-color pyrometry appears to be a useful

approach, experimental tests of the "grayness" of the relevant surfaces needs

to be made. Radiometric measurements should be included in any complete

instrumentation system, and the experience of past researchers^ ^ must be

brought to the solution of the practical problems which will be encountered.

A second method is the line reversal technique for gas temperature

measurement. In this approach the gas or plasma of which the temperature

has to be determined is seeded with a small amount of Na or K. The gas or plasma is illuminated with a tungsten ribbom lamp of known brightness

temperature T^. The Na or K will emit light (usually the resonance lines at

589 or 767 nm, respectively) with an intensity corresponding to the gas or plasma temperature Tp. The latter temperature can be compared with that of

the tungsten lamp by varying T^ until the alkali emission peak "reverses" to an absorption dip. Several variations of this basic approach are possible to

increase the speed of the measurements and to localize the volume of gas or plasma where the temperature is determined. This technique has been success1

2

fully utilized in MHD experiments.
13

A technique capable of both high speed measurement and high spatial

1

3

resolution in temperature measurement is the two line fluorescence technique.

In this technique atoms are seeded into the gas stream and excited alternately

at two different (laser) wavelengths. The atomic system is selected to have

levels with an energy difference appropriate to the temperature range of

interest; these levels are coupled by a third intermediate level. The

difference in fluorescence yield from the two levels is a measure of the

electron temperature via the Boltzmann factor.

The rotational and vibrational temperature can be determined using the

inelastic scattering from polyatomic molecules, N

2

, CO, CO

2

, H

2

O, OH”.

Raman scattering , involving either linear or non-linear (Raman gain or coherent anti-Stokes Raman scattering) interactions, has been applied in

14-15

many combustion environments. Millimeter spatial resolution and nano- second temporal resolution can be achieved. Accuracies of 5% for the

temperature range 77K to 2500K are claimed for laboratory and practical

combustion systems. Application to many fossil energy systems will require

significant new efforts.

In order to assess the accuracy of the measurement of temperature and

to better understand the processes involved in advanced fossil energy systems,

intercomparisons among the various techniques is required. Spatial profiles,

fluctuations in local temperature and non-equilibrium conditions should be

investigated.

The subject of non-contact thermometry is only briefly discussed above;

a fairly complete review of the methods and instrumentation is presented in

1 fi the Proceedings of the 10th Materials Research Symposium and the review by

Eckbreth, et al.^^

How to introduce a light beam into the gas or plasma, and how to

collect the emitted, transmitted or scattered light onto a detector present

several tough material problems. However, solutions have been found and

temperatures have been determined by means of optical techniques in MHD

experiments at the High Temperature Institute in Moscow and at the University

of Tennessee Space Institute.

Some attention has been paid to the possibility of periodic rather

than continuous measurement. The idea is to insert the probe (fiber,

thermocouple, etc.) for a short period into the reaction chamber, the

channel or the pipe, perform the measurement, and retract the probe back
14

1

8

into the wall or side arm. This requires the movement of a rod or cylinder

through a tight seal in the wall. This way the optical fiber or the thermocouple

would be exposed only for a short period and hence could survive for periods

10 or 100 times longer. The principle can be extended, of course, to many

other sensors (pressure gauges, strain gauges, sampling devices, particulate

collectors, etc.). The problem is that this approach would not solve the

sensing of temperatures and pressures at locations where continuous recording

is required for process control and/or safety,

d. Composition - Chemical

As mentioned before, coal conversion plants have a variety of extremely

harsh environments (T > 1000 °F, P > 100 atm) which tax the capabilities of

currently available instrumentation for chemical composition analysis of solids,

liquids and gases. Analytical measurements in the process stream will be

important for control, safety, and pollution monitoring.

g There is currently a wide variety of conventional analytical instruments

being considered for use in coal conversion plants. In addition to these

conventional techniques, Raman scattering, laser-induced fluorescence,

19 optogalvanic spectroscopy, and optical absorption have been suggested.

20 Nuclear techniques such as Neutron activation analysis and Mttssbauer

21

spectroscopy are also possible in situ techniques for certain analyses.

Although these less conventional techniques will require additional development,

they will serve an important purpose not only in the early stages of pilot

and demo plant activities, but they also may find occasional application in

full-scale commercial plants.

The materials problems associated with the analytical instrumentation

can be divided into three major categories: direct samplers (or side arm ports), in situ probes, and windows (optical and nonoptical). The design

of successful samplers is a materials problem in coal conversion plants

both in terms of probe survival in the harsh environment (materials

durability), and in terms of sample accuracy. Catalytic and wall reaction

effects may very well affect the sampler-based measurements (see Case Study e).

Watercooled, self-purging, and/or automatically cleaned sampling probes have

been suggested for use with mass spectrometers, (Case Study e), liquid and

21

gas chromatographs , and other sampling based analytic devices. New

materials will have to be developed for both the sampler and internal

workings of the instruments, for example, the column in the chromatographs

.
15

Chromatographs will also have to be modified to remove particulates or other phases from the process stream. The intermittent nature of chromatograph

measurements couples well with the probe purge/cleaning cycle which may be

requi red.

In situ probes have been suggested for ions, moisture, and some gaseous

species. A good example is the case of carbon monoxide detection. CO is

important for process control, safety, and pollution management. Solid state

detectors utilizing a surface effect could profit from basic materials research

1

9

on the sensor materials. The development of high temperature PZT devices

would benefit moisture analysis in the gas flow of gasifiers. The possible

use of ion selective probes, capable of withstanding the process stream

environment, will require considerable materials and design studies.

Development of window materials may also contribute to improved

non-intrusive, in situ measurement techniques. Neutron activation analysis

promises to provide a multi-element capability for an on-line analysis of

the process stream. The use of NAA and other nuclear-based analytical

techniques will require special materials for spool pieces either in the

direct process stream or in the auxiliary side arm. The materials selected will

have to be transparent to the incident and reradiated radiation and be

able to survive the erosive and corrosive environment of the process stream.

In addition, better detector materials may be required to survive the

thermal environment in the proximity of the process stream.

Optical window design will present materials problems because of the

high pressures (>100 atm) likely to be encountered. Whether laser or nonlaser optical techniques are used, the window will have to be stable

to prevent pressure changes from altering the optical path of the device.

Recessed, gas-purged windows have been used with moderate success in

MHD environments. New window materials with good IR transmission should

also be developed in support of dispersive IR analyzers. These instruments

show promise in multispecie detection, i.e., SO , NO , CO and even

A X A particulates (see below) — The use of protected, water-cooled, fiber-optic

devices coupled to UV, visible, and IR instruments for analysis will also

12 18 require materials research into more durable fibers. ’

.

e. Composition - Phases, Particulates

Many of the general considerations of section 2.1.d. are also applicable

to the measurement of the relative amounts of physical phases (solid, liquid,

gas) and particulates. The nuclear-based techniques have been suggested not
16

only as composition analyzers but also for devices to measure flow and

separate phases. This multiple capability further supports the materials

research required for appropriate spool pieces.

The use of ultrasound techniques for physical phase measurement will

require the development of high temperature ceramic transducers to be mounted

on the inside or the outside of pipes and reactors. In the latter case,

there will be a need for the development of suitable materials for

acoustic windows.

In the gas phase an accurate measurement of the particulate loading

and size distribution of particles in the stream is critical. The NSF

22 workshop on particle sizing serves as a good source for potential techniques.

Sampling techniques generally are not on line and require further operator

analysis. The lack of adequate size Standard Reference Materials for scanning

electron microscope calibration, typically used in analyzing the particulates

on a wire mesh or filter, is also a problem.

Because of the need for on-line information on particulate loading in

devices such as turbines, only optical techniques seem reasonable. If more

detail than average size and/or loading is required, laser-based Mie scattering

may be used. If less information is required, simple single and dual wavelength transmissometers may be used. " Such devices will be adequate for

monitoring the effectiveness of cyclones and other particulates precipitators

.

These devices share the "window" problems associated with optical chemical

composition analyzers (2.1.d.). The design and materials choice of the

window is again a research problem.

These transmi ssometer techniques also lend themselves to incorporation

with the fiber optic probe detection scheme,

f . Composition - Emissions

ERA standards for SOXXX , NO , CO and particulate emissions from coal

conversion plants will at least be as strict as those prescribed for the

exhaust from conventional plants. The instrumentation for monitoring these

emissions and compliance with the ERA standards are generally closely tied

together. The emission monitoring is presumed to be at the end of the process

stream (or power plant in a combined conversion power plant). In this case the materials problems become less crucial than if active process

control with monitoring earlier in the process stream is required. In

the latter case the materials problems identified in sections 2.1.d. and

2.1.e. are also applicable to emission instrumentation.
17

The window problem still exists in either case. Emission-monitoring

equipment is generally designed to be specific to a species (or total

particulates in the case of the transmissometer or turbidity monitor).

24 Simple devices like the NBS SO^ monitor which consist of a lamp, line

filter and detector are more likely to be used than elaborate remote

laser monitors. The development of more durable, alkali-resistant window

materials would further enhance the application of these simpler monitors.

2.2. Erosion and Hot Corrosion

It is probably no overstatement to say that erosion and hot corrosion

are the major degradation mechanisms in Fossil Energy Facilities. This

allegation holds for most of the construction materials, but it also applies

to the instruments that are being used to measure process parameters. This is

amply illustrated by the above discussion of flow meters, thermometers and

pressure metering devices (at least as far as the intrusive types is concerned).

The two phenomena, erosion and corrosion, are basically different effects.

25 26 Erosion is mechanical damage caused by a gas, liquid or particle flow ’

; corrosion is chemical attack. However, in coal conversion environments, the

two are so closely intermixed that separation of the damage caused by the two

phenomena is practically impossible. Nevertheless, a basic study of these

effects should at first focus on one and then on the other.

A major source of erosion in gasification processes is entrained solids.

The damage depends on many parameters of the particle laden gas stream as well

as on the properties and location of the impacted surface. These conditions

should be studied systematically. It is not enough to measure the weight

change; a careful study should be made of changes in the condition of the

surface. In the case of metals (ductile) often a crater is formed and part

of the material forms an adjacent ridge. Impact of particles on ceramic

surfaces (brittle) can produce cracks.

Erosion in liquefaction systems is of a different nature because

the particles are suspended in a liquid. However, due to the high

concentration of solids and the appreciable flow velocities the problem

still is a serious one. In many respects, less is known about the surface

damage produced by solid particulates in liquids because the problem is

tightly connected with the conditions of the slurry flow (laminar or turbulent, boundary layers, surface roughness, etc.).
18

Corrosion in gasification and liquefaction systems is a very complex

problem. Considering that in most cases one is dealing with (slightly)

reducing conditions, chemical and physical changes of the wall materials might

be caused more by species like S, C, alkalis, halides, H^O, and H, than by

oxygen. However, during the starting up period oxygen may play an important

role. Certainly, if one considers the use of oxide coatings or refractory

liners to protect the metal, the possible reducing effect of the above mentioned

elements should be appreciated.

Again, the possible degradation of the wall material (metal or ceramic)

is very different when contacted by a liquid slurry or by a gas. Above, we referred to both chemical and physical effects. In many cases the damage

is strongly dependent on the diffusion of species to and from the surface.

If a gas or liquid diffuses rapidly into the material, the added atoms or molecules may cause an expansion and cracking of the solid. At the same

time the absorbed gas can chemically attack the host material much more easily.

A major problem is to monitor the erosion/corrosion effect quantitatively.

At present most experiments are of a testing nature. Coupons are exposed for

(long) periods of time to gasification or liquefaction environments and

28 subsequently the weight loss (or gain) is being determined.

The question arises whether it is possible to follow the erosion/corrosion

behavior by means of an in-si tu measurement. Some devices are being developed

with this goal in mind; one is an ultrasonic wall thickness meter used to

29 30 monitor the erosion in slurry lines , the other is a thin film sensor. The

latter consists of an insulated thin strip of the wall material deposited

on an oxide and thus insulated from the metal wall. The thinning or thickening

of the film strip due to erosion and/or corrosion can be tracked by measuring

its electrical resistance. Of course, one has to prove the equality of the film

and the bulk material with respect to erosi ve/corrosive wear.

2.3. Fuel CharacterizatioTi^

^'^^

Coal . There is no doubt that a major deficiency in the development of all

coal conversion processes is our lack of knowledge of the composition,

structure and properties of coal. The three most important aspects of the

feedstock in coal utilization are (1) coal handling (which involves many

physical properties of coal), (2) the chemistry of coal reactions, and

(_3) emissions from coal combustion or reaction. In all three areas the
19

problems are complex, involving molecular structure of the coal, trace

constituents and such properties as porosity and moisture content. During

the last 10-15 years a number of new or refined methods have become available,

offering means to provide much previously unobtainable information.

Coal is a very reactive solid, but little is known about the

relative abundance of various groups and their "organization" within the

34

coal molecule. There is still considerable uncertainty about the

fractions of aromatic and aliphatic groups. It should be possible by

application of high resolution NMR techniques (using C as the nuclear

probe) to learn more about the nature of the carbon bond and the hydrogenation process. The resolution of the NMR technique can be increased

by using ultrahigh magnetic field, pulse sequencing, and "magic angle"

spinning of the sample. It is important that this spectroscopy be applied

to samples both under ambient conditions and at high temperatures

.

After carbon and hydrogen, the elements oxygen, sulfur and nitrogen

are the most abundant atoms present in the organic part of coal. It is

important to know not only the exact concentration of each of these elements

but also how they are bonded. Usually oxygen is determined by subtraction

after C, H, N, S and the flyash constituents have been measured. Improved

methods for direct oxygen determination, such as neutron activation analysis

would be desirable. Furthermore one would like to find out how the oxygen is

distributed over the various functional groups: hydroxyl , ether, carbonyl

,

carbonate, etc. A number of novel techniques and modified, older methods

may be able to provide the answer: energy dispersive x-ray analysis (EDX),

ESCA, NMR, IR, UV, and Raman spectroscopy all show promise. In some cases, the

solution will depend on the development of entirely new experimental approaches.

Sulfur is often present in the inorganic portion of the coal as a compound

with iron (pyrite). In that case the Mbssbauer technique can be very helpful.

Much information can be derived from the use of the isotopes u, and N in

NMR spectroscopy.

Most coals contain quite a number of trace elements in the mineral matter,

but some of these elements also are bound in organo-metallic groups. Often

it is critical to determine the amount of these trace metals; a number of

them are very toxic like As, Hg, Pb and Cd, especially in the form of metalloorganic compounds. Another metal that should be traced is Ti, because it is

a strong catalyst poison.
20

Many techniques can be used to detect these small impurities including

neutron activation analysis (NAA) and proton-induced x-ray emission (PIXE).

Besides chemical composition, an essential aspect of coal is its

physical structure. The reactive behavior, its volatility, the forming

of slurries, all depend on the pore size and pore distribution of the coal.

These two quantities are closely related to the surface area, which in

turn determines the various adsorption-desorption equilibria, the kinetics

of many reactions, etc. Several experimental techniques can be used to . study the porosity of coal: transmission electron microscopy, modified

small angle x-ray scattering, the adsorption of an inert gas (BET) and,

of course, the measurement of mercury uptake. One should realize that

these methods do not necessarily determine the same quantity. In some instances knowledge about the relative surface areas in two different

environments is sufficient. Determination of absolute surface area is

difficult.

The porosity is one of the major factors in determining the amount

of water in coal; the moisture content can be very high. A variety of

promising new methods exist for determination of moisture in coal.

Consequently, a critical step in the coal handling process is drying. This

has to be done very carefully, because dry pulverized coal can be pyroforic.

Obviously, the oxidation of coal deserves systematic study in which

surface area and porosity play an important role.

Mineral matter (slag, flyash)

Most coals contain about 10% inorganic material mainly in the form of

oxides. The most abundant are SiO^ and Al^O^, ranging from 30-65% for the

former and 25 to 55% for the latter. Because of the high silica content

coal slag may be converted to a liquid during coal combustion and other

high temperature stages of the coal conversion processes, and then solidify

into a glass or "glass ceramic" when the surrounding temperature is lowered

to between 1000 and 1500 °C, The exact crystallization temperature T^ varies

with composition. (For relatively high silica content this temperature is

about 1400 °C.) This means that it is possible to define and measure a slag viscosity above T^, but below that temperature one deals with a "glass-ceramic" and the viscosity increases in time while some crystalline

minerals phase-separate from the molten material.
21

In several coal conversion technologies coal slag will condense on the watercooled wall. This will be the case in combustors, MHD-channels

and slagging gasifiers. It is therefore important to know the chemical

and phase composition, and the physical properties like viscosity and

37

thermal conductivity as a function of that composition. As mentioned above,

in many cases solid slag will consist of a glassy matrix containing small or large islands of crystallized material. It is important - not only in

this case, but in other applications too - to determine the ratio of

crystalline and amorphous matter and, if possible, the size and shape of

the crystalline areas. This is not an easy measurement; it might involve

a combination of x-ray-, electron- and neutron-diffraction.

Another totally different, but important aspect of the mineral matter

are the particle size and composition of the flyash in the gas stream. The

simple presence of these particles is detrimental in the gas stream exiting

from gasifiers if this gas stream is used to power a gas turbine. Particle

erosion of the turbine blades (as well as the corrosion due to alkali salts)

is extremely rapid. From the emission point of view the flyash is a health hazard if it consists of glassy particles of submicron size.

Consequently, it is essential to determine the concentration of flyash

particulates in-situ (see 2.1.f) and to measure their size, size distribution

and composition on samples collected under a wide variety of conditions.

Oil Shale Kerogens

Kerogens require analytical research similar to that described for coal

and coal ash. Knowledge of chemical composition, physical properties and

molecular structure are essential for the development of oil shale technology.

Again, determination of the nitrogen and sulfur content is important; the

measurement techniques are not straightforward and require attention. Very

crucial is the determination of trace impurities because a major difficulty

with shale waste is toxicity and the possibility of polluting rivers and

groundwater.

2.4 Instrumentation for Thermal and Mechanical Properties

The reliability and efficiency of coal conversion plants depend to a great extent on the proper selection of construction materials. Considering

the very severe conditions, both physically (temperature, pressure, etc.) and

chemically (corrosive atmosphere) that one finds in most segments of such

plants, the choice of construction materials (metals, alloys and ceramics)

is very limited. Aggravating the problem is the fact that reliable, accurate

data on material properties in these extreme environments is rather scarce.
22

One of the reasons is that the measuring methods, which are reasonably

straightforward under ambient conditions, are not always easily extrapolated

to the high temperatures and pressures and chemically reactive atmospheres of

gasifiers, liquifiers and gas turbines. Nevertheless, the design engineer

needs the data. Consequently, a good case can be made for providing new or properly adapted measuring equipment to determine the much needed values of

physical properties, in particular thermal and mechanical characteristics

.

Very few commercial instruments have the special capabilities mentioned

above. Unfortunately, there is little incentive for the instrumentation

industry to develop this kind of equipment because the market is small. The

modification of existing apparatus or the design and construction of new measuring devices is left up to the ingenuity' of the scientist or engineer

who needs the data. However, much useful information could be obtained from

small groups of workers dedicated to the measurement of the required properties

under properly simulated conditions.

In many coal conversion facilities, construction materials are subject

to enormous stresses, often as a result of large temperature gradients. To

evaluate the effect of these mechanical forces it is common to assess the

condition of the component by means of a stress analysis. Such an analysis

requires an input of thermal conductivity data, thermal expansion, heat

capacity, elastic constants, tensile and compressive stresses, and values

for crack propagation and creep.

Thermal conductivity measurements are difficult and tedious. As discussed

in Appendix III (Case Study f), measurements up to 800 or 1000 °C are usually performed by means of the static technique, while at higher

temperatures the dynamic method is preferred: although both techniques

are well-known in principle, there is little agreement about the execution

of the experiment, the relative advantages under different conditions,

as well as the accuracy and the efficiency of the methods. There is a great need for standardization and commercialization of measuring equipment

and testing procedures, for automation by means of microprocessors and

data handling equipment, and for standard reference materials to assist in

the comparison of results from different laboratories

.

The dynamic technique yields values of the thermal diffusivity rather

than conductivity. In order to translate the results into heat conductivity

values one needs data on heat capacities.

J
23

Other thermodynamic properties that need attention, especially in

the high temperature range 500-1500 °C, are vapor pressures as well as melting points and boiling points. We are thinking here especially of

the construction materials. This means data on metals, alloys, ceramics,

as well as composites. Information on vaporization of Cr and Cr202 is

important both for some of the super-alloys and for refractory oxides such

as Mg or Ca-chromates. The vapor pressures vary over a wide range depending

on the oxygen pressure; the measurements should include the amounts of the

dissociation and reaction products.

All these thermal and thermodynamic parameters depend on the environmental

conditions. Melting and boiling temperatures will be affected by the pressure

of the surrounding gas (both total and partial). New measurement techniques

or modifications of DTA and TGA-methods will have to be worked out to obtain

reliable data under such conditions.

The situation is rather analogous in the field of mechanical properties.

Design of gasifiers, valves*, pressure vessels, preheaters, etc. require data

on elastic constants, creep, fracture, strength (tensile-, compressive-, yield-)

and hardness not only under ambient conditions, but also as a function of

temperature and pressure. That means for metals and alloys, temperature effects

up to 1000 °C, and for ceramics up to 1800 or 2000 °C must be investigated. High

and low pressure data are also needed.

In the field of coal conversion designers are particularly interested

in data under cyclic conditions. Often sufficiently accurate values of elastic

constants at very high temperatures can be obtained by extrapolation, if the

temperature dependence is known over an appreciable range above room temperature.

However, in order to get these data, measurements must be made at elevated

temperatures. Such experiments always involve materials problems. Either the

vibrators and transducer are mounted directly on the sample and therefore must

be able to withstand the temperature and pressure of the sample itself, or they

are indirectly coupled by means of rods or threads in which case these "couplers"

should be resistant to the severe conditions. In either case a low-loss glue

or interface material has to be found which does not critically affect (or

impede) the measurement. This is even more important when the attention is

focused on the inelastic properties . Usually, the losses are much more

sample and temperature dependent than the constants themselves.

*A1 though valves do not fall in the category of instrumentation in the strictest

sense, they do represent one of the most critical groups of control components

in coal conversion facilities. As such they do deserve prime attention w*th

respect to material research for improved operation and longer lifespan.
24

The mechanisms that govern the elastic and inelastic behavior of solids

are not well known. It is, therefore, very important that several parameters

and characteristics of the material are measured simultaneously, in order to

analyze correlations between various properties. Strength and fracture measurements should be accompanied by microstructure studies using x-ray diffraction.

38 Non-destructive evaluation methods for the detection of voids, cracks

and flaws in pressure vessels, valves, reactors, combustors, etc., require

further development. One can divide the NDE field in two categories: quality

control of the newly fabricated component by the manufacturer or by the plant

engineer, and on-line inspection during operation (or intermittently during

downtimes). Some of the most widely used methods are based on sonic or

37 ultrasonic absorption. This approach can be refined by employing multidirectional imaging techniques (tomography). Imperfections and cracks in

metals can be detected also by means of fluorescent dyes or eddy current

devices. Another way to test materials and components is to load the

part under consideration and measure its anelastic behavior. Methods for

measuring tensile and compressive strength of ceramics and metal alloys

should be extended to higher and lower temperature. One cannot rely on room temperature results only. The fact that material A is stronger than B at ambient temperature does not always mean that the same is true at very

high or very low temperature.

Of special importance for high temperature applications (heat exchangers,

turbine blades) is the group of structural ceramics: silicon nitride, silicon

39 carbide and other silicon based materials. Both the thermal and the

mechanical properties of these compounds are important; unfortunately the

measurement of these properties at high temperature is not easy.

2.5 Testing Procedures and Facilities

In practically all coal conversion technologies there is a great need

for experimental facilities where instruments and materials can be tested

under properly simulated conditions. Instrument designers lack the data

to build a proper model of a conceptual measuring device. Laboratory workers

want to try out a prototype apparatus for their bench-type set-up. Plant

operators are skeptical about the usefulness and durability of the instrument

that they are urged to use, unless it is tested under "real" conditions. The

many groups that are involved in the various stages of coal conversion R&D

agree in principle that well-designed test facilities are very useful.

However, there is no consensus how to realize this need.
25

Several contradictory arguments are being heard. The laboratory-size

test rig is rejected as too small and too much simplified to give answers about the operations in the real plant. On the other hand, in many cases

it is awkward to test the instrument in the actual plant. One cannot systematically change the flow rate, the temperatures, the pressures, etc. because

such a sequence usually interferes with the operation ofthe pilot-, demo-, or commercial plant. However, for the testing of the instrument this type of

variable, flexible program is essential.

It is clear from the above discussion that choosing the proper test rig

from the list of existing facilities is difficult. At the same time, drawing

up specifications for the construction of a new test installation is not an easy task either. The main factors are cost, test run duration, proper

simulation of operating conditions, and flexibility. A list of desired features

nearly always leads to contradictions. Consequently, one has to settle for an intelligent compromise.

The main purpose is to test the critical elements of the instrument or the material under investigation. Does the device or the component operate

well under various conditions? What is the variation with temperature? How

much? How does it behave as a function of (flow) velocity? Quantitatively!

To what extent does the instrument drift, or how much does the material

deteriorate over a period of 100 hours?

Cost was mentioned as a major factor. A working estimate for the cost

of one hour of testing in a large-laboratory size facility is 20 dollars*.

Then a 100 hour test is easily affordable. Few organizations will be able to

conduct many 1000 hour tests not only for financial reasons but also because

the facility would be tied up for too long a period. Putting the limit at

$20/hour, argues against the use of high pressure. Test facilities running

at ambient or lower pressure can be fully automated, but higher pressure

installation (even 3 or 5 atm) require constant attendance for safety reasons. This adds considerable amounts to the price of operation. Usually high

pressure is not a critical test parameter. However, there are instances

when higher pressure is important, e.g., the measurement of heat transfer

from a flow gas. In this case one can simulate the higher pressure by using

a larger flow velocity instead.

*Users fee. (Of course this-does not include the capital investment and

development cost of the test facility).
26

The one parameter that presents major difficulties is flow .^^ Both the

flow measurement and the study of flow patterns may be entirely different in

2" and 10" pipes. In this case test loops must be of sufficient size to

yield meaningful answers for pilot- and demo-plants and commercial facilities.

That does not mean that smaller test rigs are altogether useless. Certain

flow patterns, transitions from laminar to turbulent flow, erosion behavior,

etc. can be studied quantitatively in smaller set-ups. But one has to

be careful with respect to extrapolation and scale-up.

Having said all this, the fact remains that there is a great need for

properly designed test facilities: rigs that permit try-outs of various flow

meters - both intrusive and non-intrusive; similarly for temperature and

pressure devices; installations that can measure erosion and corrosion rates;

set-ups for determination of particles (amount, size, size distributions, etc.)

both in flowing gases and liquids; test equipment to determine heat transfer

and mechanical rigidity (vibrations), and chambers to determine the thermodynamics and kinetics of various coal reactions.

2.6 Data Centers

The main reason for a data center is to learn from experience and to

avoid duplication. That is true for nearly every field of endeavor. As long

as the field is reasonably limited - let us say "Metallurgy of Aluminum" - one finds that the community of experts is relatively small and homogeneous, the

literature is covered by a few journals, and communication between workers in

the field is quite good. However, in an area like Fossil Energy, the opposite

is true. The community is enormously diverse, one finds mechanical and chemical

engineers, chemists, physicists, metallurgists, ceramists, as well as applied

mathematicians and electronics experts. Even if one limits the field to those

working mainly on materials and instrumentation one still finds representatives

of all the groups listed above. How does one find information in a very

different discipline, far outside one's own area of expertise? The mechanical

engineer will ask: where do I find data on the porosity of coal (Illinois #6)?

The chemist wants to know: How does one measure the temperature of molten slag

around 2800 °F? Proper answers to these questions may save considerable

amounts of time and money. Access to a good library is not enough. One

must know where to look and therefore a knowledgeable guide is essential.
27

A well-organized Data and Information Center can be that guide. Just

as with the topic of Test Facilities one runs into the questions of size

and cost. The Center has to be of sufficient size and have an appreciable

(as well as appreciative) audience. At the same time, both the cost of

the Center and the cost to the customer should be "affordable". There is

a certain "hierarchy" in the scope and size of data centers. In increasing

order of magnitude one can rank these centers as follows:

1. Compilation of information centers, handbooks, bibliographies, etc.

2. Reference library of archival publications and reports.

3. A well organized file of reference data ("raw" or "evaluated").

4. A complete Handbook of data in the field (comprehensive).

5. A complete guide of data and performance for users and operators.

While the first and second kind of centers can be operated with a very small professional staff and a group of expert volunteers, anything

beyond that needs a full-fledged staff, fully computerized including a well-thought out system of gathering, evaluating and dissemination of

information.

Fortunately, part of such a Data Center for Fossil Energy materials is

already available. This center covers both Material and Failure information

on a level equivalent to step 3 ("evaluated"). A first edition of a Handbook

entitled "Construction Materials for Coal Conversion Performance and

Properties Data", prepared by the NBS, is expected to appear in late 1981.

What is needed is a reference system on measurement and test methods

geared to Fossil Energy requirements. That is not an easy task. Not many

scientists and engineers present in their publications a detailed description

of the equipment and procedures used in the experiments. Methods applicable

at very high or low temperatures and pressures are sometimes, but not often,

described in individual articles.

Much will depend on the ingenuity and resourcefulness of the staff

that will undertake this task. Contacts with a great variety of organizations will be essential: ASTM, ISA, Rev. Sclent. Instr., Instrument

manufacturers, research organizations of companies specializing in products

for extreme conditions. National Laboratories, University Laboratories

(with consultation of the National Science Foundation), Professional

Societies, Trade organizations and journals, etc. etc.

As with all data systems, the Center staff will have to recruit a number

of knowledgeable, responsible contributors. A well-organized data base must

be established with efficient input and output. Most important is a wel 1 -devel oped

organization to disseminate the data. Successful data systems depend on a sizable and satisfied clientele.
28

CHAPTER 3 . Suggested Program Plan

3.1 General Considerations

The program which is detailed below is the result of the deliberations of

the working group, many consultations with various experts, a number of site

visits, extensive readings of publications and reports, and experience concerning

Materials Research and Instrumentation Development within the National Bureau of

Standards.

The program plan is not all- encompassing, considering the finite size of

the resources available for this kind of R&D. The focus is on the important

areas of highest priority. As progress will be made on some projects, and new materials problems in instrumentation arise elsewhere, the plan will have to

be updated.

In the recommendations that follow the main emphasis is on medium-range

research . Nevertheless, it should be clear that the suggested projects

are selected with the goal of solving major engineering problems in materials

and instrumentation in the shortest possible time.

In recommending specific areas for exploration it is apparent that present

work in those fields is insufficient. It is also fairly certain that an appreciable amount of research, relevant to Fossil Energy Technologies, is

being performed in the nations laboratories. However, much of this work is

being done for entirely different purposes; apparently, in many cases, few

people in the Fossil Energy field are cognizant of this research.

The program has been divided into 4 major Research Areas;

I. Materials Research for Sensors

II. Properties of Coal

III. Testing and Data

IV. Exploratory Research

The first area is the largest and is subdivided into 3 subfields:

A. Erosion/Hot Corrosion, which addresses the stability of the materials

being used, B. Thermal/Mechanical Properties, a major concern in nearly

all metering devices and construction materials, and C. Other Physical and

Chemical Properties of prime importance to the design and function of sensors. Area II, the chemistry and physics of coal, has been included because knowledge

of the structure and behavior of coal is essential for control of the process

reactions, and appropriate instrumentation for these measurements is not

readily available. Area III, Testing and Data Centers, are basic requirements

for the development of better materials and instrumentation. Finally, a wellrounded program must provide opportunities for creative new ideas of great

potential CExpl oratory Research-Area IV).
29

3.2 Rationale and Recommendations

Table 1 presents a listing of the major problems in Instrumentation

related to materials. These problems are broadly defined, bringing a number

of sub-issues under one common denominator. The second column of this table

indicates the recommended materials research needed to solve these problems.

The numbers in this column refer to the suggested projects listed at the end

of this chapter and in Table 2. Column three summarizes the benefits expected

to result from the performance of this research.

Often there is not a one-to-one relation between the research and

the benefits. This is partly a result of the manner in which the research

recommendations and the expected benefits are formulated. Another reason

is that the research is generic in nature: solving a materials problem

in one field can be helpful in several other areas. Vice versa, realization

of a certain benefit requires the results from several material research

projects. The actual Recommended Research Program is summarized in Table 2.

The program suggests 37 projects in 3 major Research Areas plus "Exploratory

Research" (x projects). Each of these major areas has a few sub-areas

corresponding to the problems stated in Table 1. Details of the suggested

projects are presented at the end of this chapter. (One per page). For each

project we have indicated the purpose of the research, the possible applications

and the kind of work that should be performed. (Of course, the description of

the work is extremely condensed, and will probably have to be modified or reoriented.)

The order in which these Research Areas are presented coincides

basically with the priority ranking as perceived by the authors of this

report. This does not mean that active projects should be confined exclusively

to areas lA and IB, or lA through IC, even if funds would be severely limited.

Many other factors play a role: the quality of the project proposals, the

competence and expertise of available project leaders, the amount of work

already being performed in a particular area, the collaborative aspects of

a proposed piece of work, etc. These are arguments and factors that will

have to be sorted out by the actual Program Managers.

3.3 Level of Effort

As mentioned before, indicating priorities in the presently suggested

program is both complicated and hazardous. Many factors have to be taken

into account: emphasis on or rejection of certain technologies, political
decisions, economical conditions, funding levels, etc. In this report

most of these considerations have been ignored and an attempt has been

made to express an objective opinion.

On this basis we recommend a distribution of effort as indicated in

Table 3. The magnitude of the effort is expressed in staff years/year.

Three different levels have been indicated: the present level of support,

build-up to a minimum level to be reached in years 2 and 3, and a further

expansion to a steady state level to be maintained from the 4th year on

'

for at least 3 years. The total effort over the period of 6 years is

in rough agreement with the sum of the recommended staffing for each

of the individual projects.
Table

1.

MATERIALS

FOR

INSTRUMENTATION

IN

FOSSIL

ENERGY:

PROBLEMS

AND

SUGGESTED

MATERIALS

RESEARCH

31

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thermometers

2.

Improved

response

time

24

3.

Improved

measurement

of

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Resistance

thermometers

19

above

1000

'’C

in

harsh

environments

Piezoelectrics

(high

temp)

30

4.

More

stable

calibration

5.

Better

pressure

and

vibration

sensors
IC.3.

Composition

of

process

and

a.

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of

in-situ

analytical

1.

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process

management

exhaust

gases

and

liquids

methods

(i.r.,

Raman,

lumines2.

Increased

operational

safety

cence,

chromatography,

etc.)

3.

Improved

pollution

control

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33

Table 2. Recommended Program (Summary)

Research Area Sub-areas Project

1 I. Materials Research for Sensors

^ A. Erosion/Hot Corrosion Erosion/Corrosion by Liq/Sol. 1. Erosion by slurries

i 2. Corrosion by liquids

Erosion/Corrosion by Gas/Sol. 3. Erosion by particles in gas

4. Corrosion in Gas

;

5. Erosion/Corrosion sensors

! B. Thermal /Mechanics Measurement of Heat Conduction 6. Static Technique (Heat Conductivity)

I

7. Dynamic Technique (Heat Diff.)

I Thermal Expansion 8. Methods and Data on Thermal Expansion

1 High Temperature Heat Capacity 9. Measurement of Heat Capacity

Mechanical Properties 10. Measurement of Mechanical Strength

11. NOE for detection of cracks, voids.

C. Materials Properties for Absorption of Radiation 12. Windows for acoustic, ultrasonic

j Measurement of Process (opt., sonic, etc.) radiation

1 Parameters 13. Windows for y-ray, neutrons

14. Optical windows and fibers

Fluid dynamics 15. Two-phase flow (exp. + theor.)

16. Intrusive and non-intrusi ve flowmeters

Protective Coatings 17. Plasma sprayed coatings

18. Sputtered or CVD coatings

19. Thin film sensors (temp., strain)

Adhesion 20. Adhesion measurement and theory

Electrochemical Cell 21. Ionic conduction (S, Cl, H, —

)

Thermometry 22. Reliability of thermocouples

1 23. Fluidic thermometers

24. Optical temperature measurement

i Analysis - Chemical 25. Chromatography

I. 26. I.R. absorption, luminescence, Raman

1 27. Mass spectrometry

Analysis - Particulates 28. Detection & chracterization of particles

Analysis - Emissions 29. Devices for measurement of NO ,

i Pressure Measurement 30. High T piezoelectrics

II. Properties of Coal Chemistry of Coal 31. Structure of coal - nmr

32. Composition of coal (bonding)

Physics of Coal 33. Density (porosity) of coal (moisture)

Properties of Flyash 34. Composition & properties of flyash

III. Testing and Data Test Facilities for Fluids 35. Test loop for liquid flow

Test Facilities for Gas 36. Test chambers for combustion, gas

Data Center 37. References on materials & instruments

IV. Exploratory Research High Risk Research 38. Promising new ideas
34

Table 3. Level of Effort (in staff years/year)

Research Areas Present Minimum Steady State Total

s

year 1 year 2 & 3 yr. 4 yr. 5 yr. 6

I. Materials Research (24) (70) (70) (100) (100) (100) (464)

for Sensors

A. Erosion/Hot Corrosion 20 20 25 25 25 115

B. Thermal /Mechanical 20 20 25 25 25

' 115

C. Process Parameters N 's a ) FI ow 10 10 10

b) Temperature 5 8 8

c) Composition 5 24 8 > 30 8 CO o cn O 50 50 234

d) Level 2 2 2 e) Pressure 2 2 2

II. Properties of Coal 10 10 14 14 14 62

Ill . Testing and Data 15 15 16 16 16 78

IV. Exploratory Research 5 5 10 10 10 40

Totals 24 100 100 140 140 140 644

3 . 4 Coordination and Implementation

The implementation of the above program will depend heavily on the major policy decisions with respect to Fossil Energy development,

that will be taken in the next 6 to 12 months. It is difficult at

this point - May 1981 - to predict the future of the Synfuel program,

the MHD effort, the gas turbine technology, etc. However, supposing

that some of these programs will go forward, it will then be necessary

to pay considerable attention to Materials and Instrumentation. It is

inconceivable that the important R&D needs in this field would be ignored.

A number of general principles should be kept in mind.

- Both the organizers of the program and the participants should

constantly realize that these R&D plans are meant to be medium-range

(3-6 years). The facility operators and program managers should restrain

themselves, and refrain from pushing the various projects in the direction

of quick and shallow "results" or "pay-off".
35

- The program is meant to be interdisci pi inary . It covers in most

cases such disciplines as metallurgy, ceramics, chemical engineering, physics,

mechanics, optics (sometimes), etc. There should be close collaboration

between groups of instrumentation experts and groups of materials scientists

or engineers. Preferably groups of the first and of the second kind should

be at the same institution or even in the same laboratory. Collaborative

proposals from two or more research teams should be encouraged.

- It is essential that every research project (both experimental and

theoretical) maintains close contact with operators of Fossil Energy Test

Installations and Pilot Plants . It should be a contractual requirement

that the instrumentation and materials developers visit one or more pertinent

plants and test facilities several times a year. At the same time visits of

plant operators to the R&D laboratories should be encouraged!

- A most important aspect is close contact between the research teams

and instrument manufacturers . Project managers and monitors should realize

constantly that one of the major goals of their research is to develop

an accurate, durable device that can be used to measure an essential

parameter in gasifiers, liquefiers, combustors, turbines, etc. Consequently,

it is important to seek and maintain contact with representatives of

instrument companies and/or plant operators and encourage them to take

interest and, if possible, participate in the design and manufacturing

of the particular apparatus under development.

- Coordination and Dissemination

A key element of the suggested program must be a well organized network

of contacts between all interested parties. Scientists and engineers

have to be keenly aware of the efforts that are being mounted to solve the

instrumentation problems of this industry. Conferences, technical workshops,

and an up-to-date newsletter are essential for the success of this program.

It seems to us that the return on the R&D investment in the Fossil

Energy field could be vastly improved by a better dialogue between the

various groups involved in the research. Better links should be established

between the Fossil Energy Program in the Department of Energy and such

organizations as the Office of Energy Research (DoE), the Materials and

Chemistry Branches of NSF, as well as relevant sectors of NASA and the

Defense Department. Close ties with leading groups in industrial, academic

and government laboratories are extremely important. And last but not least
36

cooperation with working groups like SCIEP (Society for Control and

Instrumentation of Energy Processes) and professional Societies like the

Instr. Soc. of America, the American Physical Society, Am. Chem. Soc., Am.

Ceramic Society, Am. Soc. for Metals, IEEE, etc. should be broadened.

In order to carry out these functions it is recommended that the

Department of Energy specifically charges one or more persons with the

responsibility for coordination of the various program elements and

contact between all the participants.
37

3.5 Reconmended Projects

I . Materials Research For Sensors

A. Erosion/Hot Corrosion

Project 1 . Erosion by Slurries

Purpose : To improve performance of (intrusive) flowmeters, thermocouples,

thin film sensors, radiation windows, etc.

Appl i cation : Slurry pipes, reactors, preheaters, pumps, valves. Effects

on windows, light pipes, transducers, etc.

Approach :

- study erosive effects of slurries under controlled conditions of

solids concentration, particle size and shape, velocity, temperature, etc.

on a variety of materials (inconel, stainless steels, ceramics, etc.)

- investigate surface damage using optical and x-ray radiation,

electron beams, and other appropriate means.

- develop theoretical models to describe

- coordinate with projects 2, 15, 16 and

Staffi nq : 3-5 staff years for a minimum of 4

erosive effects.

35.

years

.
38

Project 2 . Corrosion by Coal Slurries and Other Coal Liquids

Purpose : To improve performance and service life of (intrusive) flowmeters,

thermocouples, thin film sensors, pressure devices, valves, pumps, etc.

Appl i cation : Separators, slurry pipes, heaters, reactors, etc.

Approach :

- explore chemical and physical attack on solid surfaces by liquids

containing sulfur, oxygen, halides and other chemical species (as well as^

fast moving particles) at high temperature, as a function of pressure,

concentration, Pj^, etc.

- characterize the surface by means of a broad range of microscopic

and spectroscopic techniques.

- describe corrosive attack theoretically.

- study the behavior of protective films (intrinsic and applied).

- coordinate with projects 1, 15, 16 and 35.

Staffinq : 3-5 staff years for minimum of 4 years.
39

Project 3 . Erosion by Particles in Gas

Purpose : To improve performance of gas flowmeters; gas analyzers;

temperature- , pressure-, level devices; transducers; surface sensors, etc.

Application : cyclones, gas turbines, gasifiers, fluid bed combustors,

stack exhaust, boiler tubes, access windows and pipe sections.

Approach :

- investigate erosive effects of particle laden gas streams under

various conditions of velocity, angle of incidence, temperature, pressure,

chemical environment, particle, size and shape. Study erosion on metals,

alloys, ceramics, glasses.

- analyze surfaces on a scale from nms to urns (thickness) employing

a broad range of techniques.

- develop theoretical models for erosive wear.

- coordinate with projects 4, 16, 28 and 36.

Staffing : 3-5 staff years for a minimum of 5 years.
40

Project 4 . Corrosion in Gaseous Environment

Purpose : To improve the quality and durability of thermometers, pressure

meters, level indicators, detectors, transducers, flowmeters, analyzers, etc.

Appl i cation : gasifiers, preheaters, burners, boiler tubes, gas pipes,

fluidized bed combustors, reactors, gas turbines.

Approach :

- study corrosive attack of solids by oxygen, sulfur, alkalis, moisture,

etc. Determine the rate determining steps, and explore the surface and surface

coatings by means of ESCA, ISS, Auger spectroscopy, etc.

- explore hot corrosion and localized corrosion.

- study the formation and durability of protective coatings (intrinsic

and applied).

- coordinate with projects 3, 20 and 36,

Staffing : 3-5 staff years for a minimum of 5 years.
41

Project 5 . Erosion and Corrosion Sensors

Purpose : To produce sensor(s) that can monitor the erosive and/or corrosive

wear of instruments and components in F. E. facilities.

Application : Boiler tubes, gas turbine blades, reactor wal Is , slurry

pipes, liners, combustors, cyclones, etc.

Approach :

- design thin film sensors that can record corrosive and/or erosive

wear using electrical, dielectric, electromagnetic, (ultra) sonic, optical,

thermal or magnetic principles.

- try to determine or estimate the lifetime of such sensors.

- if the film simulates the surface- to-be-measured prove the validity

of this simulation.

- develop and operate a meaningful program for testing of sensors in

coal conversion atmospheres.

- coordinate with projects 1-4, 19, 20, 35 and 36.

Staffing : 2-4 staff years for 4 years.
42

B. Thermal /Mechanical Properties

Project 6 . Develop Standard Techniques and Reference Materials for Heat

Conductivity Measurements between R, T. and 1000 ®C (static measurements )

.

Purpose : To provide much needed data on heat transfer through construction

and instrumentation materials, as well as process liquids and solids.

Appl i cation : Heat exchangers, combustor walls, reactor liners, transport

tubes, pressure vessels, boiler pipes, catalysts (and substrates), coal, ' coal slurries and coal slags.

Approach :

- review, compare and analyze methods reported in the literature for

the measurement of thermal conductivity of (fossil energy) materials over

the range 20-1000 ®C.

- develop (in coordination with ASTM) an appropriate static measurement

method for thermal conductivity (and related parameters if necessary) and

select suitable standards for temperatures between 20 and 1000 °C.

- concentrate efforts on steels, special alloys, selected ceramics,

composites and glasses. Study effects of density (porosity) and grain size.

- coordinate with Projects 7 and 8.

Scaff ing : 4-5 staff years for 3-5 years.
43

Project 7 . Develop standard methods and reference samples for thermal

diffusivity measurements between 25 and 1800 ®C (dynamic measurements )

.

Purpose : To provide much needed data on heat transfer through construction

and instrumentation materials, as well as process liquids and solids.

Appl ication : heat exchangers, preheaters, combustors, fluidized bed

systems, gas turbines, reactors, liners; coal, char and coal slags.

Approach :

- examine and assess techniques to measure the thermal diffusivity of

(fossil energy) materials using a pulse or periodic method (dynamic)

between 25 and 1800 ®C.

- develop (in coordination with ASTM) an appropriate dynamic measurement

method for thermal diffusivity and choose appropriate standard specimens for

the above indicated temperature range.

- concentrate experimental work on steels, alloys, composites, and

selected ceramics.

- study effects of density (porosity), grain size and defects.

- coordinate with projects 6, 8 and 9.

Staffing : 4-5 staff years for 3-4 years.
Project 8 . Thermal Expansion Methods and Data

Purpose : To assist in the selection of better matched materials for

instrumentation and construction (especially at high temperature).

Appl i cation : Ceramic liners, (surface) sensors, thermocouples, etc. in

gasifiers and liquefiers; pressure devices in fluidized beds; access windows and pipe sections.

Approach :

- Study and further develop accurate methods for measuring thermal

expansion of metals and non-metals over an extended temperature range.

- investigate what affects the thermal expansion, and how one can "tailor" the magnitude of the T. E. coefficients (density, grain size, etc.

- coordinate with projects 6, 7 and 10.

Staffing : 2-3 staff years for 3 years.
45

Project 9 . Measurement of Heat Capacity of Solid Construction Materials , Process Gases and Liquids

Purpose : To determine the thermal efficiency of coal conversion products.

Application : Gasifiers, liquefiers, pressurized bed combustors, heat

exchangers, preheaters, reactors, liners, boiler tubes, catalyst (substrates).

Approach :

- explore appropriate and convenient techniques for measuring heat

capacity at (very) high temperatures.

- provide data on selected process materials.

- coordinate with projects 7 and 25-27.

Staffing : 2-3 staff years for 3 years.
46

Project 10 . Measurement and Values of Mechanical Properties in extreme

envi ronments

.

Purpose : To increase the durability of measuring equipment and construction

materials in F. E. installations.

Appl ication : Valves, pressure vessels, reactor liners, light pipes, cyclones,

separators, boiler tubes, turbine blades, etc.

Approach :

- develop appropriate methods for the measurement of elastic and

inelastic properties at high temperatures for both metals (1000 °C) and

ceramics (1800 °C).

- design similar techniques for the determination of tensile strength,

yield strength, fracture strength, creep and hardness in the upper temperature

range (800-1800 °C depending on the material).

- construct theoretical models to explain the decrease or increase of

strength.

Staffing : 2-3 staff years for 5-6 years.
47

Project 11 . NDE inspection methods for detection of cracks, voids, etc.

Purpose : To evaluate the strength (or lack thereof) and the (im)perfection

of metallic and ceramic bodies at ambient and at high temperatures.

Appl i cation : pressure vessels, preheaters, reactors, gasifiers, liners,

boiler tubes, turbine blades, etc.

Approach :

- design or modify NDE methods to detect microcracks, flaws, and

voids in metallic and non-metallic materials. This will involve systematic

exploration of acoustic, ultrasonic, electromagnetic and other loss

techniques.

- coordinate with projects 10, 12, 35 and 36.

Staffing : 3-4 staff years for 5-6 years.
48

C. Measuring Process Parameters

Project 12 . Acoustic and Ultrasonic Transmission through various solids,

liquids and gases.

Purpose : To aid the design and construction of sonic "windows" needed for

in-si tu flow metering, chemical analysis, temperature measurement, etc.

Appl i cation : Determination of process parameters and chemical composition

of process gases and liquids in gasifiers, liquefiers, combustors, gas

turbines.

Approach :

- provide data on absorption of sonic and ultrasonic radiation in

various materials used for access windows, guides, spool pieces, etc.

- determine also the absorption of sound and ultrasound by flowing

liquids and gases (whth and without particulates); measure this absorption

as a function of various relevant parameters: temperature, pressure,

sound frequency, etc.

- coordinate with projects 15, 35 and 36.

Staffi nq : 3 staff years for 2-4 years.
49

Project 13 . Transmission of y-rays and neutrons through solids and liquids.

Purpose : To aid the design and construction of "windows" for ionizing

radiation needed for in-situ flowmetering, chemical analysis, etc.

Appl i cation : Determination of process parameters (e.g., flow velocity)

and chemical composition in liquefiers, gasifiers, combustors, etc.

Approach :

- provide data on absorption of neutrons, y-rays, x-rays in various,

materials used for access windows, spool pieces, etc.

- determine the absorption of neutrons, y-rays and x-rays by (flowing)

liquids (with and without particulates). Measure this absorption as a function of several relevant parameters: temperature, pressure, energy

of the particles or radiation.

- perform analysis of radiation from activated atoms and molecules

(NAA, fluorescence).

- coordinate with projects 15 and 35.

Staffing : 3 staff years for 2-4 years.
50

Project 14 . Optical windows and fibers

Purpose : To aid the design and construction of windows for optical

radiations (i.r., visible, u.v.) needed for flow metering, chemical

analyses, temperature recording, etc.

Appl i cation : Determination of process parameters (e.g., temperature)

and chemical composition in combustors, heaters, gasifier- and liquefiers

tubing, etc.

Approach :

- provide data on optical constants and absorption in various materials

used for windows, guides, fibers, etc. (under extreme conditions of T, P and chemical reactivity).

- furnish similar information on absorption, refraction, and scattering

of light by (flowing) liquids and gases (with and without solid particulates).

- coordinate with projects 24, 26, 28 and 36.

Staffing : 4 or 5 staff years for 4-5 years.
51

Project 15 . Fluid dynamics of multicomponent flow.

Purpose : To improve the efficiency of slurry transport and slurry flow

metering.

Appi i cation : coal/water mixing and feeding, slurry tanks, heaters, reactors

and pipes containing partly dissolved coal.

Approach :

- study two-phase (and three-phase) flow as a function of the pertinent

physical-chemical variables: particulate concentrations; shape, size, and

size distribution of particles in fluid; temperature; pressure; velocity;

pipe size; surface conditions; etc. Analyze the laminar and turbulent flow

regimes and the boundary layer behavior. Particle-particle and fluidparticle interactions in flowing systems should be a focus of activity.

- mount a significant effort in flow modeling (both 2- and 3-phase).

Assess effects of protrusions and constrictions, variable cross sections,

bends, etc. in the pipes.

- coordinate with projects 1, 16 and 35.

Staffing : 8-9 staff years for 3-4 years (e.g., 3 or 4 different groups).
52

Project 16 . Intrusive- and Non-intrusive flowmeters

Purpose : To develop improved flow measuring capability.

Appl ication : slurry transport pipes, slurry tanks, inlet- and outlet of

heaters and reactors.

Approach :

- improve intrusive flow metering technology, e.g., orifices or nozzles,

by applying flow analyses and selecting suitable materials. Make a systematic

study of the erosion (and corrosion) caused by the flow. Decrease erosive

effects by designing wall profiles for minimum turbulence.

- apply flow principles and materials expertise to the design of a non-intrusive flowmeter (e.g., ultrasonic Doppler, or thermal pulse, or

etc. )

.

- Coordinate with projects 1, 15 and 35.

Staffing : 4-5 staff years for 3-5 years, (at least 2 groups).
Project 17 : Plasma sprayed coatings

Purpose : To develop protective layers for thermocouples, fluidic

thermometers, optical light pipes, thin film sensors, sampling devices,

transducers, detectors, etc. in aggressive fossil energy environments.

Appl ication : All components and instruments in coal conversion facilities.

Approach :

- investigate the deposition of arc plasma sprayed and flame sprayed

coatings 0.1-100 ym: voltage, geometry, time (periodicity) , powder size

and composition, powder feed; substrate temperature, etc.

- explore grading by changing feed rate.

f - study the durability, as well as the structure, density and

homogeneity of these layers; also determine the diffusion and internal

stresses. Use appropriate surface and thin film analysis techniques.

- coordinate with projects 5, 19, 20, 22, 23 and 36.

Staffing : 2-3 staff years for 4 years.
54

Project 18 . Sputtered and CVD coatings .

Purpose : To develop protective layers for thermocouples, optical

light pipes, thin film sensors, transducers, detectors, etc.

Appl i cation : All components and instruments in coal conversion facilities.

Approach :

- study the deposition of sputtered and/or CVD coatings (1-100 urn):

quality of film as a function of substrate temperature and rate of deposition.

- investigate grading.

- study the lifetime as well as the structure density and homogeneity

of the above layers.

- coordinate with projects 5, 19, 20, 22, 23 and 36.

Staffing : 2-3 staff years for 4 years.
55

Project 19 . Thin film sensors (erosion/corrosion , temperature, etc.)

Purpose : To develop the thin film sensor technology for a number of

physical and chemical measurements especially at high temperatures.

Appl i cation : Monitoring of erosion/corrosion , temperature, strain,

vibration, etc. in various components of gasifiers, liquefiers, combustors,

gas turbines, etc.

Approach :

- design thin film sensors for the measurement of erosion/corrosion

,

temperature, strain, and/or flow(?) up to at least 1000 °C.

- assess the preference for plasma sprayed, CVD or sputtered films

- determine the quality and durability of these sensors.

- coordinate with projects 5, 17, 18, 20 and 36

Staffing : 2-3 staff years for 4 years.
56

Project 20 . Adhesion: measurement and theory

Purpose : Improve the adhesion of thin films, protective layers, etc. to

flat and curved surfaces of tubes, reactors, etc.

Appl i cation : Sensors, transducers, detectors, thin film thermometers

,

level- and pressure devices in gasifiers, liquefiers, gas turbines, etc.

Approach :

- develop methods to define and measure the adhesion of material A

to material B.

- study the parameters determining (good) adhesion.

- investigate the theoretical aspects of the physics and chemistry

governing the interface (bonding, diffusion, geometry, etc.).

- coordinate with projects 17, 18 and 19.

Staffing : 4-5 staff years for 4 years (at least 2 groups).
57

Project 21 . Ionic Conduction (S, Cl, N, 0)

Purpose : To develop sensors for partial gas pressures of sulfur, halides,

and other chemical species.

Application : Gas turbines, gasifiers, combustors, fractionators.

Approach :

- study the mechanisms of ionic conduction in a variety of sulfides,

oxides, halides, organics for use in electrochemical cells.

- investigate the ac- and dc-conductivity and the polarization effects

of ionic conductors where the moving species are 0, S, N, and halide ions.

- explore a variety of materials for electrodes and indicate the

advantages and disadvantages of each.

- study the durability of the ionic conductors under various conditions.

Staffing : 3-4 staff years for 4 years.
58

Project 22 - Reliability of Thermocouples

Purpose : To develop fast and reliable temperature measurement in harsh, high

temperature environments.

Appl ication : Preheaters, reactors, separators, fluidized bed combustors,

liquefiers, etc.

Approach :

- improve reliability of thermocouples, both from the durability (Materials)

and operational point of view (emphasis 400-1800 °C).

- find long-life sheathing materials resistant to chemical attack,

especially by oxygen, sulfur and hydrogen.

- study the accuracy, precision and response time.

- coordinate with project 36.

Staffing : 3 staff years for 5 years.
59

Project 23 . Fluidic Thermometers

Purpose : To develop reliable temperature measurement devices for harsh,

high temperature atmospheres.

Application : Combustors, gasifiers, reactors, fluidized beds, preheaters

,

etc.

i Approach

:

f - expand the applicability of fluidic thermometers by proper materials

research.

- improve accuracy, precision and response time. Explore different

geometries (smaller) and lighter construction.

- coordinate with projects 17, 18, 20 and 36.

Staffing : 3 staff years for 4 years.

I
60

Project 24 . Optical Temperature Measurement in Gases and Plasmas

Purpose : To develop dependable non-intrusive thermometers

.

Application : Combustors, (slagging) gasifiers, gas turbines, etc.

Approach :

- explore Raman, fluorescence, radiometric, and/or line reversal

methods for temperature measurement.

- investigate methods and design equipment to introduce light into

high temperature environments and study also high temperature detectors as well as means to extract the signal from the high-T environment (windows,

1 ight pi pes, etc. )

.

- determine emissivities of appropriate materials in the required

temperature range.

- assess durability, accuracy/precision and response time.

- look into the possibilities of intermittent measurements (e.g., insert

and retract some kind of periscope into the high temperature chamber, or reactor for short periods of time).

- coordinate with projects 14 and 36.

Staffing : 3-4 staff years for 4-5 years.
61

Project 25 . Chromatography

Purpose : To provide convenient, analytical methods for the determination

of chemical composition under difficult conditions of high temperature,

high pressure and strong corrosion.

Application : Process liquids and gases at several critical points in the

flow train of gasifiers, liquefiers, fluidized bed combustors, etc.

Approach :

- study gas- and liquid chromatography for use in fossil energy processes.

- increase processing speed and reliability.

- investigate several materials for optimum choice: e.g., samplers.

- coordinate with projects 35 and 36.

Staffing : 3 staff years for 2-3 years.
Project 26 . Chemical analysis by optical means

Purpose : To provide convenient, reliable, analytical methods for the

determination of chemical composition.

Appl i cation : Process liquids and gases at several critical points in

the flow train of gasifiers, liquefiers, fluidized bed combustors, etc.

Approach :

- explore the use of i.r. absorption, Raman scattering, and/or

luminescence for in-situ chemical analysis.

- review and select best tunable lasers, detectors, windows and

light guides (fibers?) for the above methods.

- design, build and operate at least one experimental set-up for

determining 2 or more species.

- coordinate with projects 14, 35 and 36.

Staffing : 4-5 staff years for 3-4 years (at least two groups).
63 id

Project 27 . Mass Spectroscopy

Purpose : To provide convenient, reliable, not overly costly, analytical

methods for the determination of chemical composition of gases.

Appl i cation : Process liquids and gases at several critical points in the

flow train of gasifiers, liquefiers, fluidized bed combustors, etc.

Approach :

- adapt mass spectrometry technique for real-time monitoring of

reaction products in severe environments (including high temperature,

pressure, etc. )

.

- investigate appropriate materials and suitable geometry for m.s. probes.

- coordinate with projects 25, 26 and 36.

Staffing : 3 staff years for 2-3 years.
64

Project 28 . Measurement of particulates

Purpose : To detect and analyze particles in gas streams to prevent erosion,

and avoid health hazards (exhaust).

Appl i cation : Gasifiers, gas turbines, stack gases from coal combustion

and coal conversion facilities.

Approach :

- adapt optical techniques (microscopy, holography, absorption, light

scattering) designed to measure particle concentration, size and size

distribution, for use in high temperature, high pressure, chemically active

environments.

- compare optical techniques with other methods for particle analysis;

SEM, STEM, sedimentation. Coulter counter, etc.

- develop uniform powders to be used as standards for the above methods.

- coordinate with projects 3, 14, 24 and 36.

Staffing : 3-4 staff years for 4-5 years (at least 2 groups).
65

Project 29. Measurement of N0„, C0„, S0„, etc.

A X A

Purpose : To monitor emissions and avoid (illegal) pollution.

Appl ication : All Fossil Energy Facilities.

Approach :

- modify devices, designed to detect NO , CO and SO , for use as analyzers of exhaust gases from gasification^and liquefaction plants,

gas turbines, fluidized bed combustors, etc.

- investigate and develop proper materials for i.r. and u.v. windows

and for detectors of radiation in specific spectral ranges.

- coordinate with projects 14, 26 and 36.

Staffing : 3-4 staff years for 3 years.
66

Project 30 . Materials for pressure and for acoustic flow measurement

(High-T piezoelectri cs

)

Purpose : To record elevated pressures and sonic responses conveniently

and reliably.

Appl ication : Fluidized bed installations (PFBC), gasifiers, heaters,

reactors, feedback lines.

Approach :

- investigate piezoelectric materials for use as transducers, detectors

and pressure gauges under conditions of high temperature and pressure.

- study material durability, signal stability and response time.

- coordinate with projects 16, 35 and 36.

Staffing : 3 staff years for 3 years.
67

II . Properties of Coal

Project 31 . Chemical Structure of Coal

Purpose : To provide advanced instrumentation leading to data on and

knowledge of chemical bonding in coal as a basis for predicting chemical

reactions, reaction rates, dissolution, etc.

Appl ication : Gasification and liquefaction reactions; reactions in heaters,

combustors, separators; catalytic reactions.

Approach :

- determine bonding of C and H throughout the "coal molecule", using

such techniques as high resolution NMR and IR-spectroscopy

.

- review possible other methods for probing molecular structure of coal.

- attempt to construct "coal-molecule" models.

- coordinate with project 32.

Staffing : at least 5 staff years for 5 years (2 or more groups).
68

Project 32 : Chemical Composition of Coal

Purpose : To provide advanced instrumentation for the chemical analysis of

coal especially with respect to organically bonded S, N, 0, etc.

Appl i cation : Gasification and liquefaction reactions: desulfurization, NO^

production, catalyst poisoning, etc.

Approach :

- Develop methods for the quantitative analysis of 0, S, N, Fe, alkalis,

halides. As, Ni , P, etc. in coal and determine their position and bonding, using

besides NMR such techniques as Raman and M^ssbauer spectroscopies, ESCA, Auger,

X-ray diffraction, EPR, etc.

- emphasize organical ly-bonded species.

- coordinate with project 31.

Staffing : 2-3 staff years for 4 years.
69

Project 33 . Physical-Chemical Properties of Coal

Purpose : Measurement of coal properties essential for handling, pulverizing,

dissolving and reacting of coal.

Appl i cation : Coal feeders, coal dryers, coal mixers, coal crushers.

Approach :

- measure the density of coal; determine open and closed porosity and

pore size of various coals and coal forms.

- define and determine hardness, agglomeration and volatility of coal.

- develop in-situ method for moisture analysis; kinetics of coal drying.

- measure acoustic and dielectric properties of coal.

- determine BTU-value of various coals.

- coordinate with projects 31 and 32.

Staffing : 3-4 staff years for 5 years.
70

Project 34 . Flyash (coal Slag )

Purpose : To develop measurement techniques and provide data on physical

and chemical properties of coal slag (flyash) that seriously affect coal

conversion processes.

Application : Flow and reactions of process fluids and vapors in liquefiers,

gasifiers, cyclones, gas turbines, combustors, stacks, etc, (operation,

durability, safety, health).

Approach :

- determine chemical composition and phases (including amorphous) of

flyash particles and of condensed coal slag (at various temperatures, pressures,

and flow velocities).

- measure the viscosity and volatility of molten slag; develop predictive

models as a function of composition.

- coordinate with projects 3, 28 and 36.

Staffing : 3-4 staff years for 4 years.
71

III . Testing and Data

Project 35 . Test facilities and procedures for liquid/solid flow*.

Purpose : To provide capabilities for testing dynamic behavior of fluids

and slurries of flowmeters and of other instrumentation operating in moving

fluids.

Appl i cation : Heaters, reactors, separators, transport tubes (for fluids

and slurries), and other components of coal conversion facilities containing

process fluids.

Approach :

- develop appropriate procedures for (long time) testing of liquid flow

patterns, operation and durability of various measuring devices, and the

properties of specific materials under well-defined conditions of moving liquids.

- design and build one or more loops for testing liquid and slurry flow

of sufficient size to simulate turbulent and laminar flow over an appreciable

range of velocities, temperatures, etc.; the installation must be well

instrumented and be able to accommodate a variety of flowmeters. Besides

it must contain measuring devices to record erosion and corrosion.

- coordinate with projects 1-5, 15, 16 and 22.

Staffing : at least 8-10 staff years for 6 years.

Initial capital cost: at least $750,000.

*It is assumed that the facility operators will be intimately involved in

research using these facilities.
72

Project 36 . Test chambers and procedures for gas streams and combustion*.

Purpose : To be able to test (particle-laden) gas flow patterns and

durability of instrumentation and materials in severe, high-temperature

environment.

Appl i cation : Fluidized bed combustors, gasifiers, gas turbines, gas analyzers,

sensors in reactors, cyclones, tubing, etc.

Approach :

- create facilities for testing the behavior of gas streams with and

without particles or droplets; such facilities must be extensively instrumented

for determination of flow patterns, boundary layer behavior, measurement of

particle size and distribution, and be able to operate at high temperatures

and pressures and various chemical environments.

- construct one or more combustion chambers designed for testing of

several types of metering devices including thermometers, pressure and

strain gauges, erosion and corrosion sensors; the test chamber must

provide means to investigate the behavior of flyash and condensed slag

at very high temperatures.

- develop testing procedures for (long time) testing of gas flow patterns.

- coordinate with projects 3, 5, 22, 24, 28 and 34.

Staffing : at least 5 staff years for 6 years (2 or more groups).

Initial Capital Cost: Approximately $250,000 per chamber.

*It is assumed that the facility operators will be intimately involved in

research using these facilities.
73

Project 37 . Data and information on materials for instrumentation.

Purpose : To provide a convenient and efficient data file on materials

properties and measurement techniques.

Application : All fossil energy research and development, testing facilities

and plant construction.

Approach :

- develop an information center containing physical and performance

data on pertinent materials (under severe conditions) and create at the same time a reference library and clearinghouse on instrumentation and

measurement methods relevant to fossil energy technologies.

- Optimize contacts with the entire fossil energy community. Create

effective means for input from this community and dissemination of the

Center's data and reference.

Staff i nq : 2-4 staff years for 8 years.
IV. Exploratory Research

Project 38 . Promising New Ideas (High Risk)

Purpose : Reserve funds to be able to support promising new ideas.

Appl i cation : Novel materials for new measurement techniques applicabl

in Fossil Energy Processes.

Staffing : 50 staff years total.

Possible Examples : Sintering

Combustion catalysts

Adhesion (theory and experiment)

NDE for "green shapes"

Erosion- and corrosion protection
75

References

la. C. H. Samans and W. R. Hulsizer, J. Eng. Mater. Technol . 372 (1977).

lb. S. M. Wiederhorn et al., J. Eng. Mater. Technol. 143 (1977).

2. R. T. King and R. R. Judkins, "Fossil Energy Materials Needs

Assessment", ORNL/TM-7232, July 1980.

3. Energy Materials Coordinating Committee (EMaCC). Report FY 1980

(DOE/ER-0102).

4. Fossil Energy I&C Briefs (Prepared for the DoE by JPL), Vol 2, #1,

January 1981.

5. Proceedings of the Symposia on Instrumentation and Control for Fossil

Energy Processes, 1977, 1978, 1979, 1980 (Prepared for DoE by Argonne

National Laboratory).

6. "Overview of Coal Conversion Process Instrumentation, Argonne National

Laboratory, Tech. Memorandum #1, May 1980 (ANL-FE-49628)

.

7. Technical Memoranda No. 1-10, Components Technology Division, Argonne

National Lab., 1977-1981 (ANL-FE-TM 01, 02, etc).

8. K. G. Porges, et al., in Proceedings of the 1978 Symposium on Instr.

and Control for Fossil Energy Processes, ANL-78-62, pp. 438-475.

9. P. A. Kinzie, "Thermocouple Temperature Measurements", John Wiley and

Sons, New York, 1973.

10. T, Negas, et al., Proc. of the 20th Anniversay of Fluidics Symposium

(AS), pp. 37-43 (1980).

11. See for example. Measurement of Thermal Radiation Properties of

Solids, J. C. Richmond ed. Office of Scientific and Technical Information,

NASA (1963), and Symposium on Thermal Radiation of Solids, S. Katzoff

ed. Scientific and Technical Information Division, NASA (1965).

12. Sidney A. Self, Review of Soviet Plasma Diagnostics on the U-25B MHD

Facility for Joint US-USSR Generator Studies, HTGL Report No. 116, Stanford

University, January 1980.

13. J. Bradshaw, et al., "Application of the Two Line Atomic Fluorescence

Technique to the Temporal Measurement of Small Volume Flame Temperatures"

in Characterization of High Temperature Vapors and Gases, J. W. Hastie ed.,

NBS Special Publication 561, Vol 2, p. 1079 (1979).

14. M. Lapp and C. M, Penney, Laser Raman Gas Diagnostics, Plenum Press,

New York ( 1 974)

.

15. A. C. Eckbreth, "CARS Thermometry in Practical Combustor", Combustion

and Flame 133 Cl 980).

16. J. W, Hastie, ed.. Characterization of High Temperature Vapors and

Gases, NBS Special Publication 561/2 (2 Vols), (1979).
76

17. A. C. Eckbreth, et al., "Combustion Diagnostics by Laser Raman and

Fluorescence Techniques", Prog. Energy Combustion Sci. ^ 253 (1979).

18. S. A. Self, R. H. Paul and R. Keating, A Fiber Optic Probe for

Temperature Measurements in Combustion MHD Plasmas, HTGL Report No. 120,

Stanford University, September 1980.

19. Bernard R. Cooper, Physics Today 1]_, p. 32, 1978.

20. Caroline L. Herzenberg, IEEE Trans. Nucl. Science, NS-26, 1568 (1979).

21. W. T. Smith, American Laboratory IZ, 95 (Nov. 1980).

22. Sidney A. Self, High Temperature Gas Dynamics Lab., Mech. Eng. Dept.,

Stanford Univ., Memorandum Report #18, Nov. 1980. (Report on an NSF Workshop

at Mississippi State University, September 1980).

23. S. A. Self and R. L. Keating, In-Situ Sampling Filter for High Temperature

High Velocity Flows, HTGL Report No. 117, Stanford Univ., May 1980.

24. Frederick P. Schwartz and Hideo Okabe, Anal. Chem. 703 (1975).

25. A. W. Ruff and S. M. Wiederhorn, "Erosion by Solid Particle Impact",

NBSIR 78-1575, January 1979.

26. George F. Schmitt, "Liquid and Solid Particle Impact Erosion" in

Wear Control Handbook, ASME, 1980.

27. K. Natesan, Corrosion and Mechanical Behavior of Materials for Coal

Gasification Application, Argonne National Laboratory (ANL-80-S).

28. V. L. Hill and E. J. Yeseley in "Properties and Performance of

Materials in the Coal Gasification Environment", GRI/MPC/ASM/DoE

Conference, Pittsburgh, September 1980.

29. W. A. Ellingson, Materials Technology for Coal-Conversion Processes,

Progress Reports, Argonne National Laboratory, 1980 and previous years.

30. R. R. Oils and P. S. Follansbee, "Superalloy Sensors", Superalloys : Metallurgy and Manufacture , Kear, B. H., Muzyka, D. R. , Tien, J. K. , and

Wlodek, S. T., Eds., Claitors, Baton Rouge, LA, 1976, pp. 37-44.

31. N. Berkovitz, "An Introduction to Coal Technology", Acad. Press, New

York (1979), pp. 21-157.

32. M. L. Gorbaty et al. Science 206 , 1029 (Nov. 1979).

33. E. V. Beaupre, American Laboratory 1_2, 89 (Nov. 1980).

34. Proc. of the Conference on Chemistry and Physics of Coal Utilization

W. Virginia University, June 1980.

35. C. L. Herzenberg, et al., ANL-CEN-FE-SO-12 (1981).
77

36. N. Berkovitz, "An Introduction to Coal Technology", Academic Press,

New York (1979), pp. 45-53, 324.

37. S. J. Schneider, et al.. Chapter 3 in "Current Topics of Materials

Science", Vol. 4, Ed. by E. Kaldis, North Holland Publishing Co., Amsterdam,

1980, p. 89.

38. Wolfgang Sachse and Nelson N. Hsu, Chapter 4 in Physical Acoustics

Vol. XIV , p. 277 (1979). Academic Press, NY.

39.

R. N. Katz, Science 208 , 841 (1980).

40.

Instrumentation and Process Control for Fossil Energy Demo Plants

Ann. Techn. Progress Report, Argonne National Laboratory, FE-49622-12,

October 1977.

1

APPENDIX I - Review of Major Processes

a. Coal Gasification

Gasification of coal is a technology aimed at producing gases of various

heat content by hydrogenation of coal. The basic chemistry is simple.^*

Pulverized coal is combined with steam and reacted at high temperature

and pressure to form CH^, CO, CO2, H2, and various hydrocarbons . The three

fundamental chemical reactions are:

the carbon-steam reaction C + H2O -> CO + H2

the shift reaction CO + H2O -> CO2 + H2

the methanation reaction CO + 3H2 ^ CH^ + H2O (catalytic)

At the same time a number of other reactions are involved such as

C + O2 CO2 (combustion), C + CO2 2C0 (Boudouard reaction), C + O2 ^ CO + 0,

C + 2H2 CH^, etc. The extent to which all these reactions will play a minor

or major role depends very much on the temperature and pressures being applied

and the presence or absence of catalysts. In general the caloric value of the

gaseous product, but also the complexity of the gasification facility, increases

with temperature and pressure. The various gasification techniques are usually classified on the basis of the quality (heat content) of the end

product: low BTU (100-200 BTU/scf), medium BTU (300-400 BTU/scf ) , and high

BTU (800-900 BTU/scf). The oldest technology, which reached commercial scale

in Germany in the 1930's, is the Lurgi method which produces a "syngas" of

about 170 BTU/scf at temperatures around 1000 °C and pressures of about

20-30 atm, or lower. The Lurgi process has enjoyed progressive improvements

which have increased the size and reliability of the operation. Similar

evolution has been true of the Wellman process, which yields a 170 to 200 BTU/scf

product. These oxygen-and-steam-blown reactors produce gas having typical

compositions of 50% hydrogen, 35% carbon monoxide, and 15% methane.

The Koppers-Totzek and Winkler gasifiers operate at atmospheric pressure,

generate no tars, and produce a methane-free product of approximately 30-35%

hydrogen, 45-55% carbon monoxide, and 12-16% carbon dioxide. The Winkler

process operates at relatively low temperature (900 *^0) and can only react

lignites and subbituminous coals. The Koppers-Totzek process operates at

much higher temperatures (1815-1925 °C), and can accept a wide variety of

coals of the higher rank.

*References for Appendix I at the end of the Appendix (p. 10).
2

The generation of gasifier technology currently under development in

the U. S. is suitable to produce synthetic natural gas and is intended

for consumption rates of 5 to 10 thousand tons of coal per day. These

processes rely upon the various methanation reactions to produce high quality

"pipeline" gas. Three general categories of processes may be used to

describe these gasification methods.

Category I - initial gas produced in the gasifier must proceed

through a shift reaction before it becomes "high-BTU

gas". Fluidized bed or entrained coal reactors are use^.

Category II - hydrogasification processes using steam and hydrogen

to produce methane-rich gas which needs little further

shifting to reach sufficient quality. Fluidized bed

or entrained coal reactors are used.

Category III - much the same production results as Category I but

these processes use a liquid medium in the gasification

process. These may involve some level of catalysis.

A few years ago four Category I processes were under development:

these were known by the names Bi-Gas, Synthane, Acceptor, and UCC. The

latter three have been discontinued; only the Bi-Gas pilot plant is

operating at this time.

In Category II the HYGAS process has reached the pilot plant stage.

Category III includes the molten salt process and the ATGAS (molten iron)

process. Commercialization of these technologies remains to be seen. Considerable R&D efforts are underway with several processes. Modification

of the Koppers-Totzek and Lurgi gasifiers is directed at greater flexibility

and higher pressure operation. Adaptation of the Texaco Partial Oxidation

process, developed for oil gasification, to coal gasification is

proceeding; a pilot plant using this approach is being operated. The

gas from the Texaco gasifier is being used to generate electricity by

means of gas turbines. This requires that the particulate content of the

gas be kept low by removing the molten slag at the reaction stage.

The materials and instrumentation problems in all these gasifiers

are serious. Thermocouples do not have sufficient lifetime to measure

reactor temperatures [see Case Study c (Appendix III)]. Slag causes many

difficulties: slag temperature, slag viscosity, slag thickness all are hard to measure. Determination of particulate concentration and sulfur

content CSO^) is not an easy task.
3

Pulverized coal is fed into combustors, gasifiers or reactors in

several ways: slurry pumping, lock hopper transfer, pneumatically, or

by steam injection. Char (partially combusted coal) is often injected

into a gasifier through a steam eductor, as in the BI-GAS pilot plant.

For process control and safety it is vitally important to know the char

flow. Recently some new equipment has been designed to measure the char

flow [see Case Study b (Appendix III)].

2

b. Liquefaction

Most techniques for coal liquefaction are based on the Bergius process.

Pulverized coal is mixed with a hydrocarbon liquid (which has been produced by

the process itself) and reacted with hydrogen (obtained by the gasification

of coal). The products from the reactor are separated into a light,

middle and bottom (heavy) fraction. These fractions are used for different

purposes and yield several products. Originally the operating pressures

were 175 atm and higher (at reactor temperatures of 400-500 °C) but

lately the pressures have been reduced to about 100-120 atm. During the

last 10-15 years a number of specific processes have been under development

and many have reached the pilot plant stage 4 to 6 years ago. Some of the

well-known processes are:

a) the Solvent Refined Coal Process [SRC-I (solid product) and

SRC-II (liquid product)]

b) the H-Coal Process (catalytic)

c) the Exxon Donor Solvent Process (catalytic).

A simplified schematic of the SRC-II Process is shown in Figure 1.

Proper instrumentation is a major problem in these processes; (an overview

of the multitude of measuring methods that can be used for determining process

parameters was published by Argonne National Laboratory in 1980). Measurement

of mass flowrate is a crucial parameters in the slurry streams which occur throughout gasification and liquefaction processes. Not only are solid-liquid

flows encountered but solid-liquid-gas systems are prevalent in liquefaction

reactions. Attainment of mass flowrate values requires measurement of the phase

fractions of the components of these systems is necessary in addition to the

velocity of the system. To obtain effective control of the mass balances throughout these synthesis reactions require mass flowrate values.

Other parameters that have to be measured at many different locations of

the total system are temperature and pressure. One also wants to record the

level of slurries and liquids in the heater and in the reactor.

1
PURIFIED

HYDROGEN

4
5

Finally, a number of quantities like slurry viscosity, partial pressure

of hydrogen, and sulfur content have to be known to guarantee efficient,

safe, and clean operation,

c. Direct Combustion

Fluidized bed combustion"* is strongly promoted for a number of reasons. The name "fluidized bed" stems from the fact that small coal particles are being agitated by an air stream and hence the bed of particles behaves

more or less like a fluid. Consequently, the heat and mass transfer becomes

much more efficient. Furthermore, the NO formation is reduced considerably

A

due to the lower operating temperature (750-950 ^C). Another advantage is

that SO emissions can be decreased by means of limestone addition. The

two principal approaches are atmospheric and pressurized fluidized bed

combustion (AFBC and PFBC). The latter operates at somewhat higher

temperature and takes considerably less space than conventional thermal

plants. Fluidized bed combustors can be employed to generate steam (see

Fig. 2) or to heat air. In addition, in PFBC, one can clean the flue gas

(remove particulates) and use it to drive a gas turbine.

Figure 2. Schematic illustrating

the principles of fluidized bed

combustion (from Ref. 1, p. 207).

This technology appears to be promising because there do not seem to

be major barriers to commercialization (with the exception of fireside

corrosion); besides, meeting environmental standards is quite possible.

There are a number of rather obvious instrumentation and materials needs.

As far as the feed system is considered a reasonably accurate measurement of

the coal (and limestone) solid-mass flow is required. It is highly desirable

to determine the concentration and size distribution of the particles in the
6

flue gas, as well as its chemical composition, particularly with respect to

alkali content. Another very important parameter is a reliable indication of

the bed level. One uses for the latter purpose differential pressure devices

which, unfortunately, tend to plug up. An essential measurement is that of

temperature, at several heights in the bed. Thermocouples have two problems:

short life due to the corroding atmosphere and very slow response time.

5 d. Gas Turbines

Instrumentation in gas turbines will be of particular interest in th^

1980' s. The interest arises both from the cost and limited supplies of

conventional fuels. The high cost of the fuels requires an accurate

description of the temperature and heat fluxes within the turbine in order

to optimize the operating temperature, and thereby the efficiency, while

still maintaining reasonable durability. At the present fuel cost, design

changes which effect only a 0.2% increase in the engine efficiency are being implemented. In the aircraft gas turbine industry, cost of turbine

degradation due to the use of the higher temperatures is now approaching

g $10 /year. Therefore, the potential benefits resulting from improved

instrumentation are enormous.

Gas turbines are often fueled by synthetic gas from a gasifier or from

a pressurized fluidized bed combustor. The hot gases exiting from the turbine

can be used to drive a steam generator (see Fig. 3). It is especially important that the particulate loading of the gas entering the turbine will be

maintained at an extremely low level to avoid erosion and corrosion.

The importance of understanding the dynamic as well as the average

conditions in the gas turbine introduces the need for diagnostic measurements

of gas temperatures, gas composition (particulates, alkali, etc.), velocities,

heat fluxes and corrosion and erosion rates in the combustor and downstream

turbine. Fast response instrumentation implies unique materials problems, for

the sensor dimensions must be extremely small and stable to be useful. Subtle

metallurgical solutions are required to isolate signal generating elements on compressor or turbine airfoils. A high temperature thin film technology must

be developed to enable measurements which measure the variable of interest

without perturbing the aerodynamics or heat transfer near the turbine component

or diagnostic control element. An example of design requirements for

erosion/corrosion sensors is presented in Appendix III (Case Study d).
Figure 3. Combined- cycle gas and stream turbines fueled by power gas. Air

the compressor is mixed with the gas from the gasifier and burned in the

combustion chamber. Heat in the gases leaving the gas turbine is captured

a stream boiler to produce additional power with the result of high overall

efficiency. [From "Clean Power from Fossil Fuels", by Arthur M. Squires,

from Ref. 5].

g

e, Magnetohydrodynamics (MHD ) The basic principle of open cycle MHD is the direct conversion into

electricity of the energy released by the burning of fossil fuel (coal,

oil or natural gas). Because the process takes place at high temperature

the efficiency is high. A stream of high-speed, very hot gases, produced

in a combustor and made electrically conductive by seeding with alkali,

is passed through a transverse-oriented magnetic field. The resulting

current, perpendicular to the gas stream and to the magnetic field, flows

into electrodes, which permit the passage of DC current to the load. The

gases exiting from the generator are still hot and can be used to drive

from

n
8

a conventional steam plant. Such a combined cycle plant should have an overall efficiency of 50% or more compared with about 37% for large

conventional coal or oil buring installations. Besides the high efficiency,

the fact that most of the sulfur will react with the alkali-seed and therefore

be eliminated from the exhaust makes the MHD process attractive from the

environmental point-of-view.

Realization of this promise is, however, not an easy task. The

very severe operational conditions put heavy strains on the materials

requirements. The temperature of the gas in the burner is 2600-2800 °C,

which demands intense cooling of the combustor walls. If the fuel is coal,

slag will condense on the wall and contribute to the heat insulation.

In many cases the metal is lined with a layer of refractories to produce

an additional thermal barrier. However, little is known about the thermal

conductivities of these ceramics and of solid and molten slag at these

temperatures. Such lack of data leads to large uncertainties in the

combustor design and in the parameters of the gas, seed and slag in the

burner.

Somewhat similar conditions exist in the MHD channel. The wall

temperature can vary from a few hundred °C in the case of metal electrodes

(e.g., copper) to values between 1500 and 1900 °C when the electrode

material is a refractory ceramic. The thermal flux through the electrodes

_2

and insulators can be as high 100-300 W cm . Because of their large heat

conductivity metal electrodes can be as thick as 1-10 cm, but ceramic

electrodes and insulators, being very poor heat conductors, must be 5 mm

or thinner. Hence, the thermal gradients are very high and thermal shock

resistance is an important consideration.

Furthermore the electrodes must be able to sustain considerable

_2

electrical current densities of the order of 1-2 A cm . Such large

currents can produce significant electrochemical effects, drawing K''"- and

P_L p_

Fe or Fe ions deep into the cathode (and 0 towards the anode).

The large electrical currents also produce arcing through the gas boundary

layers and breakdown in the solid slag and in the electrodes. The latter

effects are major sources of electrode degradation.
9

Finally, one has to deal with chemical interactions between seed,

slag or vapor species and the wall materials. Not the least of these

chemical problems is the absorption of water on cooling and the resulting

swelling of ceramic insulators and/or electrodes. The oxygen partial

_3

pressure next to the wall is about 10 atm which constitutes a slightly

oxidizing atmosphere, and thus gives rise to considerable metal corrosion

at these high temperatures.

Further down the flow train there are still other difficulties: air

preheater materials and boiler tubes that must be resistant to alkali corrosion

and slag particle erosion, seed recovery (which has to be better than 95%) and

finally the usual environmental requirements of low NO emissions.

A Although the problems seem to be immense, systematic materials research

and testing, as well as careful measurement of all the process parameters

should be able to provide most, if not all of the solutions. During

the last 7 or 8 years a considerable amount of materials science and

engineering, both in the Soviet Union and in the U.S. (as well as collaborative studies by the two countries),^ have greatly contributed

to a better understanding of the various physical and chemical processes

taking place along the flow train. Many tests conducted in small test

rigs as well as in large MHD-instal lations have shown that generator and

diffuser materials can survive for periods of at least 200 to 500 hours.

During these tests the importance of frequent recording of several

parameters became abundantly clear. Thermocouples embedded in the

generator walls gave continuous information about the temperature

of the channel surface (inside), the temperature of the cooling water and

the temperature gradient. These data presented an excellent check on the

operation of the main channel. Yet the thermocouples are bulky and tend to

degrade (with the electrodes). Smaller and more durable thermocouples and

protection are needed.

Much more difficult is the measurement of the surface temperature

of flowing slag. Pyrometers could be used if the emmisivity of the

slag (at approximately 1800 °C) were known more accurately.

Other quantities that are being recorded in MHD installations and test rigs are the cross channel voltages and currents. Hall angle, interelectrode voltages

and magnet current. Slag concentration and particle sizes have been measured

in one experimental MHD facility. One would like to extend such techniques

for (both slag and seed) to all MHD facilities, small and large.
10

References

1. N. Berkovitz, "An Introduction to Coal Technology", Academic Press,

New York, 1979, p. 250.

2. Ref. 1, p. 302.

3. "Overview of Coal Conversion Process Instrumentation", Argonne, Natl.

Lab., Tech. Memorandum #1, May 1980 (ANL-FE-49628)

.

4. C. L. Herzenberg, et al., "A Study of Instrumentation Needs for Process

Control and Safety in Coal Fluidized Bed Combustion Systems", Argonne

National Laboratory, Report ANL/CEN/FE-80-12, (1981).

5. A. M. Squires, Scientific American 227 , 26 (1972).

6. S. J. Schneider, et al.. Chapter 3 in Current Topics of Materials Science,

Vol. 4, Ed. by E. Kaldis, North Holland Publ. Co., Amsterdam, 1980, p. 89.

7. "Open Cycle Magnetohydrodynamic Electrical Power Generation", General

Editors, M. Petrick (USA) and B. Ya Shumyatsky (USSR), Argonne National

Laboratory, Argonne, IL 1978.
1 APPENDIX II.

a. A Sample of Organizations Involved in Research for Instrumentation

and/or Materials in Fossil Energy

Argonne Natl . Laboratory (slurry) flow, erosion/corrosion

,

temperature, chemical analysis

Oak Ridge Natl . Lab. on-line sampling, heat exchangers,

pressure vessels, coal properties

Sandia Labs., Livermore particulates, laser diagnostics

coatings, erosion (in fluids)

Natl. Bureau of Standards properties of slag/flyash, corrosion/erosion,

fracture, thermodynamics, SO , NO , Materials Data Center

Exxon Res. & Eng. Labs.

IITRI-Metals Properties Council

Stanford University

W. Virginia University

Pittsburg & Midway Mining Co. (Gulf)

Grand Forks ETC

coal properties, catalysis, valves, etc.

corrosion of metals and alloys in F.E.

plasma diagnostics, particulates (MHD)

properties and analysis of coal

coal properties, viscosity

coal analysis

Bartlesville ETC thermodynamics (coal & coal derivatives)

Pittsburg ETC

Westinghouse

combustion, catalysts

properties of materials for gasifiers, test

facility for MHD materials

Mississippi State University corrosion/erosion, seed recovery (MHD),

temperature (optical)

Univ. of CA-Berkeley

Penn State University

Montana State University

General Electric

erosion/corrosion, solubility of coal

coal characteristics, structural ceramics

transducers, electrodes (MHD)

claddings for high temperature turbines

Pratt and Whitney

Battel le

erosion/corrosion (turbines)

modeling of heat flows, erosion/corrosion

Southern Res. Institute

NASA (Lewis)

U.S. Geological Survey

Illinois Geological Survey

Purdue University

FI ui dyne Co.

Avco-£verett Research l^ab.

particulates, metal properties

new alloys for gas turbines

coal analysis

coal characterization

thermodyn. & kinetics of coal liquids

refractories ( testing-MHD)

gas flow, heat transfer (MHD)

Babcock and Wilcox stress analysis of refractories , metal

corrosion

Massachusetts Inst, of Technology

University of Minnesota

material properties at high temperature

corrosion
2

b. SCIEP (Society for Control and Instrumentation of Energy Processes)

President: Herb Kaplan, Crest Energy Systems, Inc., (Norwalk, CT)

Subcommi ttees : al Advanced Technical Requirements

b) Control Systems Development

c) Environmental Control

d) Flow Measurements

e) High Temperature

f) Level and Pressure

g) On-stream Analysis-Gas

h) On-stream Analysis-Solids

i) Particles

j) Slurry letdown valves

k) Viscometry

Principal Organizers : Nancy O'Fallon, Argonne Natl. Lab.

Harold Horowitz, IBM/FDS

John Walsh, Jet Propulsion Lab.

Peter Alexander, TRW Energy 'Systems

Herb Kaplan, Crest Energy Systems

and Fred Zweibaum, Barnes Eng.

(Radiometry)

Mike Barroody, Catalytic Inc.

Frank Finch, Los Alamos Sci. Lab.

Carol Herzenberg, Argonne Natl. Lab.

Jim Wang, Sandia Labs (Livermore)

Armand Bosso, Stearns-Roger

Joe McDonald, Haake Inc.
1

APPENDIX III.

Case Study a. Flow Measurement Research for Coal Slurry Flows

(J. R. Whetstone - NBS~)

Realization of technologies for the liquefaction or gasification

of coal on a commercial scale will require measurement capabilities for

many process parameters, flow measurement being one of the foremost.

Achievement of automatic process control capabilities will of course

require on-line measurement methods. In many processes the input to the

system involves the pulverization of coal which is then slurried with

either water or with oils recycled from the process. The Solvent Refined

Coal process is an example of this type of process fluid feedback. Automatic control of the formation of these slurries will require a flow

measurement of the slurry stream to control the material balance in the

reactor. At this point in the process the flow regime is solid-liquid

in nature. Addition of hydrogen to the slurry changes the system to a gas-liquid-solid system. The fluid dynamic characteristics of two and

three phase systems are not well understood or elucidated. This is particularly true for flow measurement technologies which are not in as mature

a state of development as are those for single-phase fluids.

The conditions imposed upon future flow measurement technologies

useful for 1 iquefication and gasification process are typical of an extremely harsh environment. The environments of liquefaction processes

are those of high density coal slurries (two or three phase) at varying

levels of temperatures and pressure. Recirculation of the slurry is done

in many processes which requires mass flow measurement of near reactor

operating temperatures of approximately 850 °C. Obviously this is a highly erosive and corrosive environment. Additionally, the properties

of the fluid further complicate the situation since the viscosity of the

recycled solvent is high approaching 2000 centi stokes.

Two generic approaches to flow measurement in two and three phase

streams may be considered, the first case is the intrusive one and

requires direct contact of the flow sensing elements with the flowing

environment, that is, modification of the streams fluid dynamic behavior

for the metering purposes. Non-intrusive devices are mounted externally

to the flow and depend upon modification of an impressed field of some type with subsequent detection of that modification by the flow. These

impressed fields, usually optical, acoustic, electromagnetic or nuclear,

must penetrate the piping containing the flow. Therefore, spool pieces or
2

windows are necessary which are either transparent or translucent to the | applied radiation field. In the case of electromagnetic and nuclear | radiation, non-ferrous materials which will withstand the erosive, corrosive ! high temperature and pressure environment are necessary. Various types of

coatings may be useful where only relatively thin layers of erosion !

i resistant materials may be laid down upon the material of the spool piece I wall. Nuclear radiations require a low absorption cross-section to achieve

penetration to the flow field. In the case of neutron activation methods '

| the spool piece must be reasonably transparent to both excitation neutrons | and the delayed gamma rays used for the measurement. | Intrusive methods have been developed extensively for single-phase

flow measurements. Adaptation of these techniques to solid-liquid or

'

solid-liquid-gas systems poses a considerable materials problem. These |

]

i methods are based upon the changes in the pressure field of the flow by | partial obstruction of the cross-sectional area of the pipe, thereby I

I producing a differential pressure. ! Nozzles and orifice plates are the most widely used geometries for

this purpose. This type of metering technique even for single-phase

fluids requires considerable research to be useful for accurate flow | measurement purposes. Empirically determined coefficients are necessary | to completely characterize metering performance. Adaptation of these

j techniques to two and three phase solid-liquid flows must be expected to

| require similar empirical methods given the current state of physical understanding for systems of this type. Therefore, values of discharge coefficients,

i.e., the ratio of observed to theoretical flow rate, will be necessary to evaluate these systems. In the case of orifice plates the discharge coefficient adjusts

for an approximate 40% difference between actual and theoretical flow rate.

Successful adaptation of these differential pressure producing flow

measurement devices is attractive because the response of the devices is

reasonably simple, well developed commercially and reliable in operation.

A materials problem has been solved in this case. Use of a superalloy, stellite, has been successful in maintaining a response that

provides process measurement information [Source: Canfield-SRC-II Pilot I Plant, Ft. Lewis, WA], although the pressure taps necessary for the differential i pressure response measurement must be opened and cleaned several times daily.

Such a high level of maintenance is not acceptable for demonstration or commercial | scale plants. Investigation of fluid dynamic phenomena around pressure taps !
3

including methods or shapes which inhibit fouling of the tap coal particles

will provide a crucial step to the use of these types of flow measurement

devices for liquefaction and gasification processes.

Utilization of intrusive devices for flow measurement will require

some level of testing under conditions similar to those of plant environments.

Therefore, the need for flow loops for testing and research and development

are a necessary step in this direction. A wide range of instrumentation

would be provided with a test bed by such a facility. Additionally, the

experimental facility would be available to perform fluid dynamic research

directed toward a broadened understanding of dense phase flow phenomena.

The greatest impact on flow measurement technology would probably be to

intrusive types of devices. Certainly such a facility would allow the

determination of discharge coefficients for differential pressure producing

devices of various geometries. Testing of phase concentration measurement

techniques would be possible in flows of known concentration.

Such a flow loop would provide the means to investigate the effect

of impingement angle upon the erosion rate of surfaces exposed to the flow.

Some theoretical and experimental efforts exist in this area although it is

not extensive [1,2,3]. Such information would provide the means to design

geometries for a wide range of uses in these highly erosive environments

which have minimum erosive and ablative characteristics. For flow metering

purposes a geometry may exist which has low erosion characteristics because

the range of impingement angles occur over a particular range. Given this

information nozzle geometries for flow measurement could be designed which

combined erosion resistant materials with minimum erosion conditions to

produce a long-lived and reliable flow measurement device. Of course, the

emphasis here is the com.bination of research in the areas of fluid dynamics

of both dense-phase and particulate laden streams and materials science to

produce useful and reliable flow metering techniques.

References

[1]

. Carter, G., Nobes, M. J. and Arshak, K. I., WEAR, ^ (1979) 245-261.

[2]

. Yeung, W. , WEAR, ^

(1979) 91-106.

[3]

. Tabakoff, W., Kotwal, R. and Hamed, A., WEAR, 52 (1979) 161-173.
I
1

Case Study b. Acoustic Char-Flow Monitors for the BI-GAS Pilot Plant*

(T. P. Mulcahey-ANL)

Backqround/Requi rements

At the request of the BI-GAS pilot-plant personnel, the ANL Fossil

Energy I&C group proposed methods of instrumenting the process to obtain

an indication of a stoppage of char flow in each of three char-flow lines.

The technique selected for development relied upon the use of a hightemperature sodium-immersible, acoustic-monitoring microphone developed

in the DOE LMFBR program. The basis for this technique was a result of

conclusions reached from an ANL test on the HYGAS pilot plant, which

indicated that the presence of fine solids in a flowing stream attenuated

sound. The microphone was selected because it could withstand the 850 °F

and 2000-psi steam environment within the BI-GAS char-flow lines.

Sensor Location/Construction

A steam eductor, used to entrain the char in the steam flow, is the

broadband noise source of the sound which was expected to be attenuated

by the fine solid char particles. A microphone was installed in the BI-GAS

reactor in the char-flow line at the position shown in Fig. 1. The

construction details of the microphone are shown in Fig. 2. The details

of the microphone installation are shown in Fig. 3, where the microphone is

placed in a holder supported by the Grayloc blind flange and then mounted

in the Tee section. Figure 4 is a photograph of the mounted microphone with

the leads penetrating the Grayloc blind flange. The microphone is positioned

in the char-flow line in a wide slot in the pipe wall, such that its outer

edge is placed even with the inside surface. The microphone is placed in

this position so that it will not be subjected to direct impingement abrasion

or erosion of the particles in the flowing stream, but will still have

a direct acoustic path from the flow stream.

Basis of Operation

Acoustic measurements were made via the arrangement shown in Fig. 5.

The measurements indicated that, within a limited frequency band, the

presence of char did attenuate the normal acoustic spectrum present during

steam flow, and hence, a signal could be derived that would indicate, in a quantitive manner, the presence of char flow. The spectral analysis of the

microphone signal is shown in Fig. 6 for various rates of char flow. In each

*This article is a summary of the information in Technical Memorandum

AML-FE-49622-TMQ8 , "An Acoustic Char Flow Monitor for the BI-GAS Pilot

Plant", by P, D. Roach and A. C. Raptis, July 1979,
2

part of the figure, the upper trace is the spectrum of the signal when only

steam is flowing in the line. The lower trace is the spectrum taken when char

is also flowing. The exact amount of char was not known, but the relative

flow rate was inferred from valve openings and readings of differential

pressure instruments. Figures 6a, 6b and 6c correspond to low, moderate,

and high relative flow rates, respectively . The lower trace in Fig. 6d shows

the spectrum with no char and no steam flowing.

Electronics

An instrument to process the microphone signal and provide both the

flow/no-flow indication and the char-density indication was designed.

The block diagram for this instrument is shown in Fig. 7. The microphone

signal is first amplified in an external charg amplifier and then is

sent to the flow monitor, where it is analyzed into three different

frequency bands by bandpass filters. The RMS detectors and LOG RATIO

converters generate a DC voltage proportional to the log of the ratios

of the amplitudes in the frequency bands. The A signal is the lowestfrequency component and is least attenuated by the char, so this signal

is taken as the amplitude reference. The other two signals are then

normalized to this reference, the result being fed to a voltmeter for

the intermediate band and to a voltage comparator for the high-frequency

band. The high frequencies are most sensitive to the presence of char,

and this signal (signal C) is used for the flow/no-flow indication. Whenever

the high-frequency signal drops below a certain level relative to the lowfrequency band, the CHAR FLOW light turns on. The intermediate-frequency band (signal B) is less sensitive to the

presence of char, but gives a usable signal over a wider range of char

density. This band is used to give a continuous indication of char density.

It is expected that the signal derived from this intermediate-frequency

band can be calibrated in terms of actual mass density of char in the pipe.

Then, if flow velocity can be determined, the mass flow rate of char would

be obtained.

Other features that have been incorporated into the flow monitor

permit external use of its signals and provide indications of proper

operation. Both voltage and current outputs are provided for driving a recorder or a process-control system with the char-density signal. These

outputs have adjustable gain and time constant. The flow/no-flow signal

is used to provide a contact closure for an external alarm system. But
3

the contacts will close only if the unit has power and the input signal

is within specified bounds. This guards against misleading CHAR FLOW

indications that might be based on signals outside the range of accuracy

of the circuit.

Front-panel indicators show if the input signal is too large or small,

and the panel meter may be used to check various circuit voltages. But

for comprehensive testing of circuit function, it is necessary to inject

known test signals. For this purpose, a separate test module has been

constructed. This module provides four different signals designed to

confirm proper operation of all the flow-monitor circuits. In this way,

each flow monitor can be quickly checked out, either as part of a routine

maintenance procedure or when the operator suspects a malfunction. The

finished flow monitor is shown in Fig. 8. Three identical modules are shown, one for each of the three char- feed legs. Also shown is the

module used for testing the flow monitor.

Other Applications and Needed Research

This acoustic-attenuation technique is generally applicable to the

measurement of sol ids-density flow and, when used in conjunction with

cross-correlation techniques to get flow velocity, mass flow can be obtained.

In the case of BI-GAS, a source of broadband noise was already present in

the flow stream; for other flow streams, an acoustic source may have to

be introduced. Development of such sound sources may be useful for other

applications involving this technique.

The ANL high-temperature microphone can be used as a transmitter but

it is not very efficient, particularly in a gaseous environment. The

microphone does not lend itself for use at high-power, high-frequencies

and, new bonding construction techniques would be needed to use it for an effective transmitter.

To make the acoustic attenuation technique useful for highertemperature fossil-fuel combustion/conversion applications (above the

650-750 ®C limit of the microphone), new sensors/sensor construction, or new techniques of measurement using existing sensors must be developed. Two

basic deficiencies limit the use of the microphone sensor at high temperature.

1. Despite the fact that the lithium niobate piezoelectric element

in the microphone has a Curie point of about 1200 ®C, the apparent

resistance of the microphone decreases to a point where the signal

conditioning equipment fails to operate as temperatures approach

700 °C. This is due to the low source impedance of the lithium

niobate. To correct this, either new piezoelectric materials or new methods of amplification are necessary.
4

2. At temperature above about 500 °C, the oxygen consumption in

the microphone becomes excessive to the point where, after an interval of a few months at 650 °C, the sensor can indicate a short and fail to operate. Upon replenishment of the oxygen

supply in the sensor, the faulty operation is corrected. For

applications where the sensors cannot be accessed, an oxygen

reservoir is provided to extend the time interval between

regenerations . Selection of materials to slow down the absorption

of oxygen from the surface of the lithium niobate or incorporation

of materials to provide sufficient oxygen is needed.
PRODUCT

GAS

Fig. 1 Schematic Diagram of 31-GAS Reactor
DIAPHRAGM

(2)

6

C\J

CQ

CVJ

V— X

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2

Construction

Details

of

High-Temperature

Microphone
7 }

Kig. 3

Microphone

Houaing

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BI-GAS

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of

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9

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10

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6

Spectral

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12

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Photograph

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(ANL

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113-79-133K)
1

Case Study c. Temperature Measurement in Coal Gasifiers (G, W. Burns - NBS)

Second generation coal gasification technologies, such as the BiGas and

Hygas processes, under evaluation for producing pipeline quality high BTU

gas, place severe operating conditions on materials and components. The most

severe conditions occur within the gasification zone of the reactors where a high temperature, high pressure, erosive and corrosive environment exists

which can quickly destroy conventional materials and components. Of the new gasification technologies, some of the most stringent material requirements

are associated with the BiGas process, owing partly to its higher operating

temperatures.

According to Pitcher [1], one of the most critical components needed

for controlling and monitoring the BiGas gasification process is the high

temperature instream temperature sensor. The sensor should record the

gas-particle stream temperature with an accuracy of 0.5% or better, should

have a life of 8000 hours or more, and should have a time response of less

than 0.5 seconds.

The BiGas pilot plant, which was put into operation in 1976, has a 2-stage, entrained-bed, high pressure, oxygen-blown, ash-slagging gasifier.

In stage 1 of the gasifier a mixture of hot char, oxygen, steam, and fuel

gas is injected by way of three char burners. Finely ground, pulverized coal

is introduced into the gasifier, along with steam, by two coal injectors

located just above stage 1. (See Fig. 1 of Case Study b). In most runs the

gasifier is operated with the containment vessel pressurized to 750 psig.

Temperatures in stage 1 are typically 1450 to 1650 °C while the temperatures

in stage 2 (entrained-bed section) range from about 750 to 1000 °C.

In the approximately 2-meter high stage 1 zone, there are three pressure

taps located near the top, middle and bottom of the zone for installing

temperature sensors. The pressure taps are water-cooled and will accept a device having a diameter of up to 17 mm. Four similar taps are also spaced

through the stage 2 zone which is about 8 meters high and has a 0.7 meter

inner diameter.

It is interesting to note that when the BiGas plant was put into

operation, thermocouple assemblies consisting of tungsten-rhenium thermocouples protected by a molybdenum disilicide coated molybdenum sheath inserted

in a silicon carbide thermowell were installed in stage 1 and 2. Many

failures of these thermocouple assemblies occurred in both stages after

operating times of less than 50 hours, due both to mechanical breakage and to

what appeared to be chemical attack or solution of the silicon carbide

thermowell £2].
2

These failures prompted plant personnel to experiment with various

materials for thermowells. They found that assemblies consisting of stainless steel thermowells and stainless steel sheathed, compacted MgO-insulated,

Type K thermocouples provided much improved performance in stage 2. As far

as stage 1 is concerned, various materials, including alumina, mullite,

zirconia, beryl lia, molybdenum, and a molybdenum-zirconia cermet were tried

but they offered little improvement. Of all the materials evaluated to date,

chromic oxide coated molybdenum thermowells have provided the longest service

(50 to 200 hours) in stage 1. The plant is currently operating using such

thermowells in stage 1, along with tungsten-rhenium thermocouples of the type

described previously.

Post- test studies of thermocouple assemblies removed from stages 1 and 2 of the BiGas gasifier have been carried out at NBS [3]. Examinations of stage 2 assemblies that had about 200 hours of service revealed

little corrosion or erosion of the stainless steel thermowells or of the

stainless steel thermocouple sheath. However, the thermoelectric output

of the Type K thermocouples was found to be low by the equivalent of 25 °C

at 1000 °C, due to the preferential oxidation of chromium in the Ni-9.5% Or

positive thermoelement.

Examination of several of the chromic oxide coated molybdenum

thermowells, that had about 15 hours of gasifier service during a run in

which the char feed rate was believed to have been about 24% higher than

that normally used, showed that the chromic oxide coating had been completely

removed and that the wall thickness of the thermowell had been reduced by as much as 0.8 mm. The molybdenum thermowells were also very weak due to the

formation of a grain boundary phase.

Thermocouple assemblies using the new highly stable, nickel-base

thermocouple called Nicrosil/Nisil [4] have also recently been evaluated

in stage 2 of the BiGas gasifier. Thermocouple assemblies, constructed by NBS,

consisting of a stainless steel sheathed, compacted MgO-insulated, Nicrosil/

Nisil thermocouple protected by an aluminized type 310 stainless steel

thermowell have been operated for up to 600 hours in the gasifier. Post-test

examinations have revealed calibration changes of less than 10 °C in the

thermocouples and no evidence of any appreciable compositional changes in

the thermoelements. In addition, virtually no corrosion or erosion of the

aluminized stainless steel thermowells was detected.
3

It seems likely that the necessary lifetime requirements can be met with

such assemblies, but their response times are much too slow (minutes). However,

the possibilies of using smaller devices fabricated from the same materials

to gain a faster response appear promising in stage 2.

It is highly unlikely, however, that the necessary lifetime and response

time requirements can be met with contact type thermometers in stage 1.

Hence, development of non-contact thermometry techniques for such measurements

is considered essential. Even so, work should continue to develop better

materials for protecting contact type thermometers and to perfect more functional types and designs of such thermometers, since they will be needed to

assess the accuracy of non-contact thermometry measurements.

Some investigations using an integrated radiometric system for determining temperatures in stage 1 of the BiGas gasifier have already been

reported by Zweibaum et al. [5,6]. They encountered problems with

interpretation of the spectral test data owing to difficulties with keeping the

instrument aligned and with keeping the fields of view of the two sensing heads

superimposed. The alignment problem was aggravated by the small available

diameter of the pressure tap in the gasifier wall. Nevertheless, their

preliminary measurements showed that the two-color ratio technique is an appropriate technique to use for such temperature measurements.

References

[1] Pitcher, N. D., BiGas High Temperature Thermocouples - Design

Considerations and Operating Experience, Proceedings of the 1977

Symposium on Instrumentation and Process Control for Fossil Demonstration

Plants, Chicago, Illinois, July 13-15, 1977, p. 367, (ANL-78-62).

[2] Walker, K. E., Status of the BiGas Pilot Plant Program, presented at

Ninth Synthetic Pipeline Gas Symposium, Chicago, Illinois, October 31 - November 3, 1977.

[3] Burns, G. W. and Scroger, M. G., Development of High Temperature

Instrumentation for Coal Conversion Plants, DOE/NBS Interagency Agreement

No. EA-77-01-6010, Technical Status Reports for June 1978 and October 1978.

[4] Burley, N. A., Powell, R. L., Burns, G. W., and Scroger, M. G. , The

Nicrosil versus Nisil Thermocouple: Properties and Thermoelectric Reference

Data, Nat. Bur. Stand. (U.S.) Monogr. 161, 167 pages (April 1978).

[5] Zweibaum, F. M., Kozlowski, A. T., and Surette, W. E., Integrated Radiometric

System for Gasifier Temperature Measurements - Part 2, Proceedings of the 1979

Symposium on Instrumentation and Control for Fossil Energy Processes, Denver, CO,

August 20-22, 1979, p. 442 (ANL-79-62/C0NF-79055)

[6] Zweibaum, F. M., Kozlowski, A. T., Lamontague, J. J., and Surette, W. E.,

Integrated Radiometric System for Gasifier Temperature Measurements - Part 3,

Proceedings of the 1980 Symposium on Instrumentation and Control for Fossil

Energy Processes, Virginia Beach, Virginia, June 9-11, 1980, p. 300

(ANL-C10-62/C0NF-800602).

1

Case Study d. High Temperature Gas Turbine Erosion/Corrosion Thin

Film Sensors and Related Devices (R. R. Oils - NBS)

There is a wide range of applications for durable thin film devices

for harsh, high temperature environments. Measurements of fundamental

properties such as temperature, pressure, velocity and heat flux in such

environments require unusual effort and even the simplest of thin film

devices will have an immediate impact. For example, thin film devices

recently developed for the gas turbine industry are deposited directly

on turbine airfoils where they provide the surface temperatures and

strains in the complex air cooled turbine components - for the first

time. Furthermore, in combination with wide bandwidth gas temperature

measurements, the surface temperature measurements have provided the

first measurement of the local heat transfer coefficients on the airfoils;

the data provided a new understanding of the heat transfer to and within

the airfoils and lead to new and more efficient airfoil cooling designs.

In this Case Study, the application of thin film airfoil and control

devices is examined with regard to the engine operation and materials

design of the thin film devices.

Introduction

Conventional surface measurement techniques on turbine airfoils

perturb the boundary layer on the surface of an airfoil or the heat

flows within the airfoil to the extent that detailed analyses of the

data are quite difficult. This problem is particularly acute in cooled

turbine airfoils, where increases in the turbine inlet temperatures have

been accompanied by complex air and water cooling designs and attendant

reductions of the component cross sections. To meet this need, a new technology for constructing arrays of thin, insulated, sensing films

directly on turbine airfoil surfaces must be developed.

While the use of thin film sensors for low temperature surface

measurements has been common for some time [1,2,3], practical thin film devices

for use in harsh environments must satisfy several design constraints which

preclude the use of conventional methods and materials of construction and

severely limit the choice of alternate materials and techniques of construction.

There is a new method of construction of high temperature thin films [4,5]

which has provided the first thin film turbine airfoil devices in large scale

aircraft gas turbine and a brief review of this technology serves to introduce

the potential and problems of high temperature thin film devices in gas turbines.
2

State of the Art of High Temperature Thin Film Turbine Airfoil Sensors

The existing method of high temperature thin film construction uses

a thermally grown metal oxide to electrically insulate the sensing

element from the substrate. In this technique, a turbine component is

coated with an alloy capable of growing an adherent, high dielectric

strength metal oxide. The coated component is then oxidized and arrays

of sensors and leads are sputtered on the oxidized surfaces. Wire leads are attached to the sensors and the assembly is reoxidized. The

development of practical surface sensors for use in harsh environments

is primarily dependent on the development of a coating which is compatible

with the substrate material and capable of growing useful insulating

surface oxide layers. For turbine alloys, the iron base alloy, Fe 25 Cr

5 A1 O.IY, has been selected from the group of MCrAlY high temperature

alloys which form adherent oxides during oxidation. An extensive

investigation of the electrical properties of the oxides grown

on these alloys led to the initial selection of FeCrAlY. The dielectric

4

strengths of oxides grown on this alloy (5 x 10 V/cm at 1093 °C) are high

-8 -1 -1

and the conductivities of the oxides (10' ohm' cm' at 1093 °C) are low [6].

In addition, the alloy has desirable mechanical properties throughout the

operating range of the sensors and devices using this alloy are usually

durabl e. Each element of the sensors is chosen for its specific electric,

chemical, or mechanical properties and, as a result, it is necessary to

combine materials with widely varying types of chemical bonding. The

metal oxide is an insulator with strong ionic bonds, the coating is a high temperature metal alloy and the sensing element is usually a noble

metal alloy 1-2 ym thick. Therefore, when the temperature of the assembly is

changed, thermal mechanical strains develop within the assembly. In a gas

turbine, the assembly experiences unusual thermal mechanical strains during

normal operation [7,8]. When the engine is decelerated from takeoff to idle,

a compressive strain of 1.7% (5,860 MN/m stress) is developed in the

uniform oxide layer. At imperfections in the oxide, shear tractions are applied to the metal/metal oxide interface and cause a concentration of

inplane stresses at the interface. In addition, the combustor exhaust

gases induce small, high frequency temperature oscillations at the metal

surface; in a typical gas turbine [9], the oxide and metal coating near the

surface oscillate ±5 ®C several times a second (6-8). These temperature
3

2

oscillations induce only a ±60 ym/m strain (±21 MN/m stress) in the oxide

and a ±120 pm/m strain (±12 MN/m stress) in the coating but the latter

strain is adequate to cause plastic deformation of coatings which are sufficiently weak and ductile to accommodate the strains associated with

the large infrequent temperature cycles. The deformation of the substrate

displaces the surface material into the boundary layer where the oxide

and metal are apparently subjected to additional large heat flows.

The resultant thermo-mechanical strains within the assembly can be

accommodated by a limited number of techniques. A scanning electron

micrograph study of devices after extensive use in laboratory combustor

exhaust gases shows that, in general, the thermal strain in useful (1-2 pm)

thin oxides is stored as elastic strain energy in the oxide, while strain

relief in usable thick (2-5 pm) oxides occurs by buckling and attendent

plastic deformation of the substrate. It is concluded that, in order for

the sensor assembly to remain intact, it is necessary to select a system

in which: 1) the compressive shear stress of the oxide is greater than the

buckling stress of the oxide when it is attached to the coating, 2) the metal

oxide/metal interface yield and shear strengths are greater than the coating

yield strength, 3) the coating yield strength is small and 4) the coating is

ductile over the entire operating range of the sensors. In successful devices,

the oxide buckles and cracks when the assembly is thermally cycled, but the

strain relief within the coating is sufficiently uniform that the oxide layer

remains attached to the coating and continues to insulate the sensing film from

the coatings. FeCrAlY satisfies these requirments; the oxide is adherent and the

material is sufficiently weak and ductile throughout the operating range that

thermal strain relief occurs primarily by oxide buckling and deformation of

the FeCrAlY.

The thermomechanical strains across the noble metal/oxide interface are much smaller since the thermal expansion coefficients of both materials are similar and the yield stress of the noble metal is low. However, it was found

that high velocity combustor exhaust gas flow over the sensors does cause delamination of the sensing elements deposited on smooth oxide surfaces. There is no significant bonding between aluminum oxide and useful noble metal alloys, and

therefore, the films must be mechanically attached to the oxide. The coating

is abraded before oxidation in order to cause the growth of an irregular oxide.

The films are then sputtered Into the irregular surface and interlocked with

the oxide. This technique is quite successful. At present, the sensors fail

after 20 hours in 1093 °C combustor exhaust gases due to gradual carbon particle

erosion of the films or changes in the electrical properties of the films.
4

The thin film sensors represent quite a change in turbine airfoil

instrumentation. The oxide layer and coating are common to high temperature

turbine components and the only alteration in the component configuration

is due to the thin, 2.5 urn, sensing films. These films are over two

orders of magnitude thinner than the conventional strain and temperature

sensors which are externally applied to the airfoil surfaces or placed

in slots in the airfoil surface. The sensor height is five to ten times

smaller than the critical height which will cause a disturbance of the

boundary layer on a turbine airfoil. The thermal impedance of the

sensor elements is over one thousand times smaller than the thermal

impedance of the boundary layer on the turbine airfoils or the airfoil

wall. Therefore, the sensors do not perturb the airflow near the component,

the heat flow from the gas stream to the component, or the heat flow

within the component. The sensor metallurgy is based on the superalloy

and coating technology developed for gas turbines so that the sensors

can be applied to a number of common gas turbine component alloys.

A primary use of the sputtered sensor technology is the measurement

of steady state and wide bandwidth surface temperatures of stationary

and rotating turbine components. In general, useful information is

received within a 0-1000 hz bandwidth with an accuracy equal to standard

grade platinum-platinum/rhodium thermocouples. In principle, any array

can be sputtered on an airfoil using available, high resolution, microcircuitry

masking techniques. The rugged nature of the sensors and ability of the FeCrAlY

coating and adherent aluminum oxide to endure most superalloy forming and heat

treating cylces suggests that the sensors can also be sputtered on subassembly

surfaces which can then become internal surfaces in a final assembly. The

heat transfer to a component and heat fluxes within the component can be

described in some detail from the steady state temperatures measured with

arrays of sensors on the component surface or combinations of internal and

external sensor arrays.

The local heat transfer to an airfoil in combustor exhaust gases

can also be obtained from an analysis of the surface temperature waves

induced by the combustor exhaust gas temperature fluctuations. Surface

temperature Fourier components within the 2-200 hz bandwidth have been

found useful for this purpose^*^; these Fourier components are rapidly

attenuated near the surface of the component and the ratios of their
5

amplitudes to the amplitudes of corresponding gas temperature Fourier

components are a simple function of the local heat transfer coefficient.

Both turbine airfoil temperature and heat transfer coefficient measurements

have been measured in large scale aircraft gas turbines using these sensors.

The sputtered temperature sensors have been used in dynamic oxidation

experiments where they have provided the first direct measurement of

surface temperature waves which can damage the protective metal oxide and

significantly increase the rate of oxidation of a material. The thermal/mechanica

strains induced near the surface of aluminized superalloys in gas turbine main

burner exhaust gases do cause fragmentation and separation of the protective

aluminum oxide and it is suspected that the gas dynamics of some high

temperature gas streams found in power generating units may also significantly

affect the oxidation and corrosion processes in these units.

It is apparent that a wide range of sensing elements can be applied

to the surface of a component once an adherent, high dielectric strength

oxide layer is developed on the component. For example, a temperature

compensated strain gauge would consist of a strain sensing Pt-W element and

a Pt/Pt-10% Rh thermocouple. Any number of arrays can be contemplated to

provide temperature compensation because the temperature and strain

sensing elements can be sputtered in such intimate arrangements that the

temperature compensation is quite accurate. In these devices, a thin

protective aluminum oxide layer would be sputtered on the assembly to

reduce the rate of oxidation of the strain sensing element.

Erosion and salt deposition monitoring devices can also be constructed

on the surface of turbine components. In laboratory combustor exhaust gases,

it has been found that the life of the thermocouple elements on small cylinders

is a sensitive function of the hard carbon particle density and the position

and thickness of the sputtered noble metal films. The rate of erosion of an airfoil in an engine can be observed while the engine is operating by monitoring

the resistance of platinum or other films -sputtered on the airfoil or by

inspection of the films after an engine test.

Pronounced hot corrosion is caused by ash deposition on the surface of

the turbine component. However, the rate of ash deposition is a complex

function of. the chemistry of the ingested gases, combustion dynamics,

and the air. flow and temperature along the turbine airfoil. Therefore,

it is difficult to predict the rate of ash deposition in an engine. The

problem can be avoided by sputtering thin films of reactive nickel-base
6

alloys on an airfoil and monitoring the degradation of the films through

changes in their resistivity or thickness. In this manner, it should be

possible to isolate those engine conditions which cause extensive ash

deposition and to monitor the total amount of ash deposition in an operating engine. Alternatively, electrodes could be sputtered on the

airfoil and the deposit characterized by the electrochemical potential

developed between the electrodes.

The Elements of a Thin Film Sensor Program

The goal of a program on high temperature thin film sensors is to

supply generic background information on methods of construction and

signal generation for practical thin film devices. The information

falls into 2 categories: accommodation of the thermal mechanical strain

with the sensor and signal generation.

A systematic study of methods of accommodating thermal mechanical

strains has both an analytical and experimental component. The analytical

effort would concentrate on analyses of potential films from the literature

data and the application of large scale finite element computer codes to

model the thermal mechanical strains within the sensors. The experimental

effort would evaluate several alternate means of storing or relieving

the thermal mechanical strains, i.e., stored elastic strain, controlled

buckling and plastic deformation, control of the relative values of the

compressive shear and buckling stresses of the films, control of the

relative values of the interface tensile and shear strengths at several

interfaces within the assembly, and control of the relative yield strengths

of the films. Experimental films and devices would be constructed and

evaluated in a variety of static and dynamic environments, including a controlled hot gas stream apparatus. Evaluations of the film and sensor

composites would be conducted using state of the art optical, SEM, TEM,

EPMA etc. techniques.

The objective of this part of the effort will be a set of specific

device components to meet specific needs. Pursuit of these objectives

will lead to the generic understanding of the thin film behavior in

harsh environments, and the general rules and design concepts for the

construction of such thin film devices. The work will break new ground

and establish new rules since parallel efforts are not underway in other

laboratories.
7

Thin film signal generation at high temperatures is an equally

fascinating subject. Stable films can generate a signal, such as a thermoelectric emf or a change in resistivity due to changes in temperature

or strain. Alternatively, the film can intensional ly interact with the

environment as in the case of new corrosion and erosion films now being

developed for corrosion control in gas turbines. In this case, the

chemistry of the film is altered to respond to specific deleterious

chemicals in the environment and reaction with the chemicals changes the

properties of the film. The films can also consist of grating arrays

which are passive and simply scatter or absorb signals from external

sonic or optical excitors. These devices can be used to measure surface

displacements or to investigate optical processes in the gas stream

between the light source and the thin film. Passive or active high

temperature optical mirrors are a simple example application of this

type of technology.

Therefore, the second part of the effort would examine signal

generation in high temperature thin films. Understanding and developing

methods of signal generation at high temperature requires advanced solid

state studies of the films, with specific focus on the film transport

properties. In stable films such as strain gauges, it will be necessary

only to study the impurity transport and stability of the film. In other

instances, more involved descriptions of ionic and electronic transport

across high temperature semiconductors which require collective and localized

electron models to describe the behavior of the outershell bonding and non- bonding electrons will be necessary. Alternate forms of signal generation

would be investigated. The initial studies would concentrate on devices to

measure, temperature, heat flux, and corrosive conditions to 4500 °F. The

theoretical and experimental effort would concentrate on the description

of thin films generated in the laboratory. The goal of this part of the

effort would be a specific set of devices and a general background to develop

design concepts for high temperature thin film devices.

References

1. Burger, H. C. and Van .Citter, P. H., "Preparation of Bismuth-Antimony

Vacuum Thermal Elements by Vaporization", Z. Phys. Vol . 66^, 210 (1930).

2. Harris, L. and Johnson, E. A., "Technique of Sputtering Sensitive

Thermocouples", Rev. Sci. Inst. 153 (1934).

3. See, for example, Chopra, K. L., Thin Film Phenomena , McGraw Hill,

New York, 1969.
Dlls, R, R., "Process of Coating a Gas Turbine Engine Alloy Substrate"

U. S. Patent 3,890,456, 17 June 1975.

Oils, R. R. and Follansbee, P. E., "Superalloy Sensors", SUPERALLOYSMETALLURGY AND MANUFACTURE, Kear, B. MuzyL, D. R. , Tien ,TT, 'and Wlodek, S. T., Eds., Claitors, Baton Rouge, La., 1976, pp. 37-44.

Dlls, R. R. and Follansbee, P. S., "Electronic and Ionic Conduction

in Aluminum Oxides Grown on High Temperature Metal Alloys", presented Symposium on High Temperature Electron and Ion Transport in S olids.

El ectrochemi cal Society Meeting, San Francisco, May 12-17, 1974.

Wells, C. H, , Fol lansbee, P. S., and Oils, R. R., "Mechanisms of Dynanlic Degradation of Surface Oxides", STRESS EFFECTS AND THE OXIDATION OF METALS

J. V. Cathcart, Ed., AIME, New York, 1975, pp. 220-244.

Dils, R. R. and Follansbee, P. S. , "Dynamic Oxidation and Corrosion in

Power Generating Units", CORROSION, No. 11, p. 385, 1977.

Dlls. R. R. , "Dynamic Gas Temperature Measurements in a Gas Turbine

Transition Duct Exit", J. OF ENGINEERING FOR POWER, TRANS. ASME, Vol

95, Series A, No. 3, July 1973, p. 265.

Dils, R. R. and Follansbee, P. S., "Heat Transfer Coefficients Around

Cylinders in Crossflow in Combustor Exhaust Gases, J. OF ENGINEERING

FOR POWER, TRANS. ASME No. 4, p. 497 (1977).
1 Case Study e. Analysis by High Pressure Sampling Mass Spectroscopy

(P. K. Schenck - NBS)

Analytical measurements in the process stream of coal conversion

plants will inevitably involve the use of sampling probes for either

"off-line" or on-line" chemical analysis. All of the sampling-based

diagnostic tools of potential application in monitoring the coal conversion

processes are presently limited by materials durability problems associated

with the sampler. In order to economize on instrumentation, devices

with multispecie capability are favored over species-specific devices.

A multispecie analytical capability can readily offset the cost or complexity disadvantages of more sophisticated instrumentation.

The high pressure sampling mass spectrometer is a multi specie

device potentially applicable to real-time monitoring of reaction intermediate

concentrations in coal conversion processes (including laboratory, pilot

and full-scale plants). A typical mass spectrometer system consists of

a sampler, high capacity vacuum system, ion source and mass analyzer.

Materials durability problems are primarily associated with the sampler.

The mass spectrometer sampler, as with samplers for other possible

instruments, must not only survive the coal conversion environment, but

must reliably and accurately sample the process stream. This latter

aspect has been particularly problematical in the use of microprobes for

NO^ determinations where secondary reactions occur on the internal walls

of the probe (depends on wall material and geometry. Molecular beam probes,

on the other hand, minimize the chance for such wall reactions.

The sampler design and material selection thus becomes the critical

element in the application of mass spectrometers to "on-line" in situ

analysis. In the molecular beam sampling approach, the probe usually

consists of a sampling cone (which is usually water cooled) backed up by

second cone or skimmer. The purpose of the skimmer is to sample only

the center of the gas jet formed by the supersonic expansion of the

sampled gas into the mass spectrometer. Probe theory exists for relating

probe geometry, skimmer geometry and probe-skimmer spacing to gas pressure

and thermodynamic characteristics. In practice, compromises in design are made because of materials durability problems. Probe theory for pressure

much above one atmosphere, such as those encountered in coal gasifiers and

turbines, may require some extension.

Adaptation of the high pressure sampling mass spectrometer to the

problem of monitoring reaction intermediates in the coal conversion process

will require a systematic study of probe design and materials under the
2

aggressive conditions of high temperature, pressure and reactive gas. Only

a few preliminary studies have been carried out even for laboratory systems.

Typical high pressure sampling mass spectrometer systems have been used in

the laboratory to sample atmospheric flames at temperatures as high as 2500 °C.

The one atmospheric pressure at the sampling orifice is reduced in stages to

%10"^^ atm at the mass analyzer. Species concentration of >10’^ atm in

the original sample gas can be analyzed with 20-50 percent accuracy. Corrosion

problems particularly of the sampling cone and skimmer were severe in the

flame environment. Alkali metals, NaCl , NaOH, NaSO^ (and K analogues)

as well as acid oxides such as SO

2 are particularly corrosive. These species

are present in many combustion systems and certainly will be present in coal

gasifiers. Hastie"* (1973) at the National Bureau of Standards carried out some preliminary work which lead to the development of ceramic probes

suitable for highly reducing (fuel rich) flames. Four materials were

studied: silica, alumina, Ca-stabi 1 ized zirconia, and lava - a commercially

available aluminum silicate with the latter material selected for routine

use. The choice of lava as a probe material was based on its ready

machinabi 1 ity in the raw form and its resistance to thermal shock and

corrosion. Alkali metals and acid oxides are highly corrosive at high

temperatures and will quickly destroy the integrity of metallic sampling

cones. Further work in characterizing lava and similar possible sampler

materials is needed.

Other species of interest in coal conversion processes such as N

2

, NO^,

C

2

, H

2 O, H2

, CH^ and other simple hydrocarbons (product gas) are no problem

for the mass spectrometer. Many other species, too numerous to list, have

9

been studied by mass spectrometers attached to combustion systems . More recently, probe measurements have been reported in combustor

systems and jet engines. Greene et al (1978) of the Midwest Research

Institute have used mass spectroscopy to study coal dust/air flames.

3 Workers at Aerodyne Research have used mass spectroscopic determinations

of ion concentrations in simulations of MHD plasmas. In this work, a coal burner (coal dust/air) heavily seeded with K

2

CO

2 was used to simulate

a coal-fired MHD generator. The predominant positive ions observed with

the mass spectrometer were potassium and the other alkalis (Na"^, Rb"^,

Cs"^). In addition, several negative molecular ions, OH" PO

2 ", etc., were

observed. Other trace species, including heavy metals, were detected

as neutrals. Th,is application used a cooled stainless steel sampler.
3

In order to prevent plugging by condensing slag or seed particles, a nozzle plug cleaner was incorporated in the design. The design of a nozzle with a material capable of surviving the 2000 °C plus temperatures

and alkali environment would have allowed continuous sampling without

the periodic mechanical plug cleaning which would be necessary in practical

plant applications. Large temperature gradients between the probe and

sample gas also have undesirable effects in perturbing the gas composition.

4 / N Miller (1978) at Aerochem Research has carried out similar studies in

flames to study ion-molecule thermochemistry . Miller was particularly

concerned that his sampling procedure would freeze out any chemistry to

assure that his measurements accurately reflected the presampling

environment in his burner. A simple gas dynamic model of his sampling

cone indicated that only reactions involving the major constituents of

the sampled gases would proceed at rates fast enough to affect the

accuracy of the sample. Miller concentrated on the negative ion chemistry

of species such as 0H~, Cl", and several metallic oxide ions. The

choice of specific probe design and types was also a topic at the 1976

AIAA 14th Aerospace Sciences Meeting. Several papers in the published

5 proceedings will provide the reader with a tutorial on probe design and

selection.

A major stumbling block is still the effect of the probe on the

measurement to be made. Will the probe walls act as a catalyst, or can they successfully freeze out the reaction intermediates? Only a few

simultaneous in situ versus probe concentration measurements have been

made in combustion environments. McGregor (1976) reported that the ijn

situ concentrations of NO., were much higher than probe-sampled measurements

X

in a jet engine exhaust. The order of magnitude discrepancy points out

the problem of accurate probe sampling, even if the probe can survive

the environment. McGregor's work used optical absorption techniques for

both the in situ and probe measurements. More recently Cattolica et al^

(1980) at Sandia reported on the comparison of in situ laser absorption

spectroscopy for OH concentration measurements versus mass spectrometric

probe measurements- in a methane-air flame. While there was reasonably

good agreement in the two techniques, the probe measurements were shifted

downstream relative to the in situ absorption measurements. This work

also points out the need for careful probe design to reduce composition

changes during sampling.
4

Systematic studies at the laboratory and pilot plant level are needed to develop high pressure sampling mass spectrometer probes capable

of surviving coal conversion atmospheres. These studies should include:

1. Thermodynamic calculations should be made of the phase fields

formed between candidate metal and/or ceramic probe materials

and coal conversion atmospheres. From these calculations, the

most promising materials would be selected and probes of

various geometries designed. Some materials may be excluded

on thermal stress grounds (e.g., high purity alumina).

2. These probes would then be tested for their durability and sampling

fidelity in laboratory atmospheres at temperatures, pressures and

gas compositions representative of coal combusion/gasification

3. Probes could then be tested for their accuracy by simultaneously

using in sifu optical techniques such as laser absorption and

tomographic^ analysis in conjunction with the mass spectrometer

to map out species concentration in a simulated coal conversion

envi ronment.

4. Successful probes would then be tested in pilot plants for

their durability and accuracy.

5. Once demonstrated, a program could be developed where an HPMS

system would be installed at a selected pilot plant for systematic

in situ analysis of process gas compositions.

References

1. J. W. Hastie, Combustion and Flame , 21 , pp. 49-54 (1973).

2. Frank T. Greene, Jacob E. Beachey, and Thomas Milne, in 10th Materials

Research Symposium , NBS Special Publication 561, p. 431 (1979)

3. J. C. Wormhoudt and C. E. Kolb, ibid ., p. 457.

4. W. J. Miller, ibid . , p. 443.

5. Experimental Diagnostics in Phase Combustion Systems , edited by B. T. Zinn,

(Vol. 53 in progress in Astronautics and Aeronautics), particularly the

contributions by Bowman, Miller and Cernansky in Chapter 1 (1977).

6. W. K. McGregor, in Combustion Measurements, edited by R. Goulard,

p. 325 (1976).

7. R. J. Cattolica, S. Yoon, and E. L. Knuth, Sandia Report #SAND80-8804

(1980).

8. Tomographic analysis is a reconstruction of point-by-point information

from the "1 ine-of-sight" data typical of optical absorption experiments.

9. See C. Stearns and F. Kohl in ref. 2.
1 Case Study f. Measurement of Heat Conductivity (H. P. R. Frederikse - NBS)

Every form of coal conversion, be it production of gas or liquid

fuel or electricity, involves a host of thermal processes. Heat is

produced, absorbed, transported or converted into another form of energy.

In all these processes, heat transport or heat flow plays a very important

role. The heat is transported through a wall material or through the

fuel itself; solid, liquid or gas. Consequently, knowledge of the thermal

conductivity of these materials is essential for the design and operation

of most components of coal conversion facilities. It is hardly necessary

to emphasize the importance of this parameter in heat exchangers and

boiler tubes, both with respect to the metal wall and the ceramic liners.

The same holds for the construction materials of combustors, as well as (pre)heaters and reaction vessels for gasification or liquefaction. Particularly

important are heat conductivity data for the selection of MHD-electrodes

and for direct or indirect air preheaters. The temperature and hence

the operation of catalysts and catalyst beds depends on the thermal

transport of the catalytic materials and their substrates.

In many cases useful data can be found in the literature especially

when the material is a well-known commercial metal, alloy or ceramic,

and the temperature range in question does not exceed 800-900 °C. To

find reliable values for the thermal conductivity of newly developed

materials or specially treated materials appears to be more difficult

especially at temperatures above 1000 °C. One should not forget the

importance of the heat conductivity of the fuel and its various components.

Little is known about the transport of heat through coal, coal slurries,

coal slag (both in the solid and molten state), and through the product

fluids. In many instances the heat flow is determined more by the

heat resistance of the surface or interface than by that of the bulk

materials. In general, it is difficult to determine the appropriate

heat conductivity of non-homogeneous materials (which are abundantly

used in coal conversion technology)! What is the heat conductivity of

a cermet (ceramic-metal) composite? How does the heat conduction of a ceramic brick depend on its porosity and on the material in the pores

(liquid or gas)? How does one analyze the heat flow through a powder

or through a phase-separated alloy or ceramic?
2

Yet two other material aspects require good thermal conductivity data:

modeling of heat flow through multicomponent walls, and the calculation

of stress patterns in solid components (often produced by large temperature

gradients). An example of the first one is the work of J. R. Schorr at

Battel le who has designed a conductivity model for the transport of heat

through a multilayered refractory-1 ined wall. With this computer model one can explore the effects of voids, cracks, gas composition, temperature

and pressure for a variety of materials.

The second aspect is illustrated by various stress analyses, (using a finite-element approach), aimed especially at the design of ceramic components

for turbines, combustors and heat exchangers. Both thermally and mechanically

induced stresses are being calculated and mapped.

The question arises: What is the reason that heat conductivities of

materials are infrequently investigated, measured and analyzed? Is the

feeling prevalent that there are enough reliable heat conductivity data

and that better or more accurate values are not needed? What is the

reaction of the designer who finds two sets of data on identical (?)

alumina differing by factors of 2 or more? Or is the reason of this neglect

that the study and measurement of heat conduction is not "exciting" enough?

Or perhaps that the measurement methods are complex and tedious and the

equipment expensive?

All these arguements do not carry much weight. The fact is that there

is a need for good heat conductivity data, that the science of heat flow is

interesting (especially when one takes a broad spectrum of material and

environmental conditions into account), and that the measurement methodology

requires a lot of attention!

It might be worthwhile to review the scientific situation with respect

to thermal conductivity as it appears at this moment. This can best be done

by discussing 4 aspects of the problem. Although it is always dangerous to

mention only a few names, it seems appropriate to indicate some of the leaders

in these 3 areas:

1. General Phenomenology (metals, semiconductors, insulators, magnetic

materials, etc.).

Two textbooks have appeared in the last 5 years: one by J, E. Parrott

and D. Stuckes ("Thermal Conductivity of Solids", 1975) and the other by

R. Berman [“Thermal Conduction in Solids", 1976).
3

2. Theory of thermal conduction in solids

The Dean of the field is P. G. Klemens, both with respect to low

temperature processes, and more recently also concerning high temperature

mechanisms, (see Chapter 1: "Theory of the Thermal Conductivity of Solids" in

"Thermal Conductivity", Vol. 1, Ed. by R. P. Tye, Acad. Press, New York, 1969).

3. Measurement methods

Many static and dynamic techniques are described in detail in the

2-volume book by R. P. Tye cited above.

4. Data Collection and Dissemination

Much data can be found in the files of the Thermophysical Properties

Research Center at Purdue University, until recently headed by Y. S. Touloukian.

1 . General Phenomenology

Because A(=thermal conductivity) is a function of T, the gradient

in Q

= aA^ should be small; this way one can determine A at a particular

temperature, rather than over a range of temperature. Thermal conductivities

cover a range of some 5 to 6 orders of magnitude. Copper is thought to

be the best conductor, but in the temperature range around 20 K sapphire

has a larger conductivity (of the order of 100 W cm~^K~^). On the other

hand, fibrous materials have the lowest heat conductivity amounting to

-4 -1 -1

about 2 X 10 W cm deg at room temperature, with large contributions

from the trapped air, from convection and from radiation. It is often

difficult to find a material with a desired heat conductivity in a particular temperature range. The reason, of course, is that the right

conductivity is not the only condition that has to be satisfied. Often

the material has to be a conductor, corrosion resistant, able to withstand

alkali and/or sulfur attack, and mechanically strong. Consequently,

the choice is narrowed considerably and often such a material does not

exist. In those cases one would like to know how the heat conductivity

can be increased or decreased by changing the physical and/or chemical

properties of the material. Very little is known except qualitatively

how the heat conductivity varies with alloying, phase distribution,

impurity content, density, grain size, crystallinity, etc. The other

approach to modification of the heat conductivity is to cover the material

with a (thin) coating, e.g., a metal layer on a ceramic, or a glassy film

on a (porous) ceramic.

2. Theory

Understanding the fundamentals of heat conduction in solids is difficult

because the variety of heat transport mechanisms is great and most of these

mechanisms are complex. The following listing gives some idea of this complexity.
4

In a crystalline solid heat can be transported by electrons, by

lattice vibrations (phonons), by magnetic excitations (magnons) and by

photons (radiation). However, none of these "particles" or modes have

infinite mean free path. The thermal conductivity is limited by a host

of scattering processes:

1) phonon-phonon (mainly 3 phonon, but also higher order) . Without

going into detailed explanation, it is interesting to enumerate the variety

of P-P processes: Normal and Umklapp processes, processes involving

acoustic and/or optical phonons, longitudinal and/or transverse phonons,

each having their own u- and T-dependence.

2) Electron-phonon (and phonon-electron)

3) Phonon-paramagnetic ions or phonon-magnon

Scattering of phonons, electrons, or magnons by:

4) Point defects (impurities, isotopes, vacancies)

5) Grain boundaries, dislocations, strain fields

6) Mixed composition (solid solution, alloys)

7) Multiphase composition (phase separation, ceramic and metal,

crystalline and amorphous, solid and liquid, solid and gas)

8) Voids (effect of density)

9) Anisotropy

Often one has to consider non-crystalline materials; glasses, polymers,

liquids. Theoretical treatments of these materials are still in their infancy.

While it is often possible to separate some of the mechanisms (or

reduce them to a negligible contribution) at (very) low temperature,

at high temperature a large portion of the above list comes into play

and therefore analysis and understanding becomes a very tough task.

3. Measurement Techniques

The various methods can be classified as follows:

1) Static (thermal conductivity ) a) linear flow: bar, disc, composite (standards)

b) radial flow

c) Joule heating (for conductors)

2) Dynamic (thermal diffusivity ) a) periodic heating: bar, disc

b) pulse and flash heating

Although this is not the place to elaborate about these techniques, a few

remarks are in order. The static measurements are reasonably straightforward

they work well especially at very low temperatures. At temperatures

above 50 or lOOK and up to 1000 or 1200K the static methods are quite
5

useful if one pays sufficient attention to proper (heated) guards and

thermal insulation. The purpose is to establish a precise, wel 1 -control led

linear heat flow pattern. As a result, the static methods are time

consuming. The accuracy of these techniques usually is of the order of

25%. To attain this accuracy it is recommended to use a comparative

method employing one or more sets of standards. Also, to facilitate the

establishment of a true linear heat flow and increase the precision, it

is recommended to use a microprocessor for the sensing of the temperature

indicators, the control of the heaters and the feedback between these systems.

At high temperatures, above 600-1200K (depending on the material) the

static methods do not give reliable results because of the rapidly increasing

heat losses (especially radiative). The effect of high temperature radiation

losses can be minimized in the periodic technique using frequencies of 0.02-200 Hz,

and in the flash method limiting the pulse to milliseconds. The dynamic

technique requires proper temperature sensors with sufficient sensitivity

and fast response time (i.r. detectors and photomultipliers). A second

detector or pyrometer can be used to measure the mean temperature.

The major feature of the dynamic method (thermal diffusivity) is that

it requires knowledge of the specific heat in order to translate the

results into heat conductivity data. In many cases at high temperature

one can use the 3R approximation for C^. If experimental values are required,

the measurement of heat capacity may present problems in some cases.

In general, dynamic methods give not as high a precision as static

methods. However, they are much faster. Static measurements often

take several hours for one point at one temperature. On the other hand,

the results can be more precise and the technique lends itself to

simultaneous measurement of other parameters (e.g., electrical conductivity

as well as Hall and Seebeck effects for electrical conductors).

4. Data and Standards

Parrott and Stuckes state that "thermal conductivity data (published

by the TPRC at Purdue University) show a disparity in data probably greater

than that of any other physical property". The discrepancies are always

several or many percent, and may be as high as an order of magnitude. Much of

this diversity stems from poor measurements, although some of it is due to

the variation in materials. Two rules should be kept in mind when providing

thermal conductivity data: 1) The apparatus should be checked by measuring

one or more "standard" samples. Unfortunately , no set of standard reference

materials exist which cover the range of heat conductivities. 2) The material
6

should be well-characterized by providing such information as source of the

sample, chemical analysis, fabrication treatment, density, grain size, crystal

structure, orientation of sample with respect to heat flow, as well as shape,

size and density.

Recommendations

The above discussion leads logically to a suggested research program:

1. Systematic investigation of the thermal conductivity especially at high

temperature up to at least 2000 °C. Study of transport and scattering

mechanisms one by one and comparison of anticipated results with those

expected for pure, high quality, strain free single crystals: analysis

of the effects of imperfections, many phases, voids, etc. (see listing

on p. 4 of this Case Study).

2. Development of a reliable, reasonably inexpensive apparatus using

the static comparative technique and a microprocessor for temperature,

heat flow and feedback control.

3. Refine the dynamic method, improving laser heating, sensitivity of the

temperature sensor, optical signal transmission and develop a convenient recording and data acquisition system.

4. Develop sets of standard reference samples both for the static and

for the dynamic technique. Compare results of the best of both techniques.

5. Maintain and strengthen a high quality data base system connected

with many reliable measurement laboratories and providing good and

fast information to all interested customers.
APPENDIX IV: MiniWorkshop

On request of the sponsors of this project a one-day workshop was held at

the National Bureau of Standards to discuss the report and to provide the

Department of Energy (Fossil Energy Program) with additional comments on the suggested program plan.

The participants in this exercise were:

T. K. Lau

S. J. Dapkunas

R. Skaggs

J. Carr

R. Gottschalk

S. Wolfe

N. O'Fallon

R. L. Anderson

J. V. Walsh

R. V. Shanklin

C. Semler

H. Frederikse

R, R. Oils

G. Burns

J. Whetstone

J. Hastie

S, J. Schneider

T, Negas

DoE (FE)

DoE (FE)

DoE (FE), guestworker from LASL

DoE (FE)

DoE (Energy Res. Office)

DoE (Energy Res. Office)

Argonne National Laboratory

Oak Ridge National lab.

Jet Propulsion Laboratory

TRW (Energy Office)

Ohio State University (Dept, of Ceramics)

NBS

NBS

NBS

NBS

NBS

NBS

NBS
Distribution List

Department of Energy (20)

National Bureau of Standards (20)

Nancy O'Fallon

A. C. Raptis

T. P. Mulcahey

W. A. Ellingson

R. L. Anderson

J. R. Hightower

J. V. Walsh

Peter Alexander

R. V. Shanklin

R. Eustis

Sidney Self

W. M. Roquemore

R. Jaffee

D. Canfield

S. Petty

B. R. Rossing

D. Murphee

J. Honig

R. Braunstein

A. V. Levy

J. C. F. Wang

Herb Kaplan

F. M. Zweibaum

M. J. Baroody

B. R. Cooper

A. J. Forney

F. T. Finch

G. J. Lapeyre

Martin L. Gorbaty

Roland L. Schmitt

Delbert E. Day

Robert J. Stokes

C. E. Semler

R. Essenhigh

Roger Staehle

H. Kent Bowen

J. Lambert Bates

D. Eastman

Argonne National Lab.

Argonne National Lab,

Argonne National Lab.

Argonne National Lab.

Oak Ridge National Lab.

Oak Ridge National Lab.

Jet Propulsion Lab. (Pasadena, CA)

TRW Energy Systems (Lakewood, CO)

TRW (McLean, VA)

Stanford Univ (Dept, of Mechanical Engineering)

Stanford Univ (Dept, of Mechanical Engineering)

Air Force Aero Propulsion Lab (Dayton, OH)

EPRI (Palo Alto, CA)

Pittsburgh & Midway Mining CO (Ft. Lewis, WA)

AVCO (Everett, MA)

Westinghouse Res. Lab. (Pittsburgh, PA)

Mississippi State Univ. (MHD Energy Center)

Purdue Univ. (Dept, of Chem)

UCLA (Dept, of Physics)

Lawrence Berkeley Lab.

Sandia-Livermore Labs.

SCIEP (Norwalk, CT)

Barnes Engineering (Stamford, CT)

Catalytic, Inc. (Wilsonville, AL)

U. of West Virginia (Dept, of Physics)

Forney Engineering CO (Colorado)

Los Alamos Scientific Lab.

Montana State Univ. (Dept, of Physics)

Exxon Corp. Research Science Lab (Linden, NJ)

General Electric Research & Dev. Center (Schenectady, NY)

Univ. of Missouri-Rol la (School of Mines and Met.)

Honeywell Corp. Materials Science Center

Ohio State Univ. (Dept, of Ceramics)

Ohio State Univ. (Coal Research

Univ. of Minnesota (Metallurgy Dept.)

MIT (Ceramics Dept.)

Battel le (Pacific Northwest Lab.)

IBM (Yorktown Heights, NY)
|j- U.». OEPT. or COMM. 1. PUBLICATION OR

REPORT NO.

2. Performint Orjan. Report No. 3. Publication Dat«

1 BioLIOGRAPHIC DATA

i SHEET (See instructions) NBSIR 81-2348 September 1981

4. TITLE AND SUBTITLE

MATERIALS FOR INSTRUMENTATION FOR FOSSIL ENERGY TECHNOLOGIES

5. AUTHOR(S)

H. Frederikse, P. Schenck, G. Burns, R. Oils, J. Whetstone

6. PERFORMING ORGANIZATION (If joint or other than N&S. see instructions)

national bureau of standards

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

S. Type of Report & Period Covered

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City, State. ZIP)

Department of Energy

Fossil Energy

Washington, DC 20545

10. SUPPLEMENTARY NOTES

1

1 Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information, if nocumeni includes a signifn.Jnl

bibliography or literature survey, mention it here)

This report reviews the materi3ls problems relsted to instrumentation for

Fossil Energy Facilities. It discusses requirements for measurement of

process parameters (flow, temperature, pressure, chemical composition), of

construction material properties, and of fuel characteristics. The main

part of the report is a suggested program plan for pertinent material k&d.

Short descriptions of the various Fossil Energy Processes, listing of present

research activities, and a set of 6 "Case Studies" are presented in an_

Appendix. ^

12. <EY WORDS (Si* to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

Coal ; -control ; Fossil Energy; materials; process parameters; research

recommendations -

13. AVAILABILITY

'/y 1 Unlimited

i 1 For Official Distribution. Do Not Release to NTIS

1 1 Order From Superintendent of Documents. U.S. Governm.eni Printing Office, Washington. D.C.

20 -*02.

[~Xl Order From National Technical Information Service (NTIS). Springfield, VA. 22I6I

14. NO. OF

PRINTED PAGES

135 : 15. Price

S12.50 i ^ i

1

1 IL

L