Dist. Category UC-90C

MATERIALS RESEARCH FOR CLEAN UTILIZATION OF COAL

QUARTERLY PROGRESS REPORT

January 1 - March 31, 1978

Samuel J. Schneider

Project Manager

FILE COPY

OCT 17 )979

Center for Materials Science

National Bureau of Standards

Washington, D. C. 20234

PREPARED FOR THE UNITED STATES

DEPARTMENT OF ENERGY

Under Contract No. EA-77-A-01-6010

"This report was prepared as an account of work sponsored by the United

States Government. Neither the United States nor the United States

Department of Energy, nor any of their employees, nor any of their

contractors, subcontractors, or their employees, makes any warranty,

express or implied, or assumes any legal liability or responsibility

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."

EA-6010-15

Dist. Category UC-90C

MATERIALS RESEARCH FOR CLEAN UTILIZATION OF COAL

QUARTERLY PROGRESS REPORT

January 1 - March 31, 1978

Samuel J. Schneider

Project Manager

Center for Materials Science

National Bureau of Standards

Washington, D. C. 20234

PREPARED FOR THE UNITED STATES

DEPARTMENT OF ENERGY

Under Contract No. EA-77-A-01-6010

"This report was prepared as an account of work sponsored by the United

States Government. Neither the United States nor the United States

Department of Energy, nor any of their employees, nor any of their

contractors, subcontractors, or their employees, makes any warranty,

express or implied, or assumes any legal liability or responsibility

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

PAGE

I. OBJECTIVE AND SCOPE OF WORK 1

II. SUMMARY OF PROGRESS TO DATE 1

Articles Published and Talks Presented 3

III. DETAILED DESCRIPTION OF TECHNICAL PROGRESS 4

1. Metal Corrosion 4

a. Slow Strain Rate Test 4

b. Pre-Cracked Fracture Test 12

2. Ceramic Deformation, Fracture and Erosion. ... 20

3. Chemical Degradation 24

a. Reactions and Transformations 24

b. Slag Characterization 28

c. Vaporization and Chemical Transport 34

4. Failure Prevention 40

a. Failure Information Center 40

b. Materials Properties Data Center 44

I. OBJECTIVE AND SCOPE OF WORK

Coal Gasification processes require the handling and containment of

corrosive gases and liquids at high temperature and pressures, and also

the handling of flowing coal particles in this environment. These severe environments cause materials failures which inhibit successful and longtime operation of the gasification systems. The project entails investigations on the wear, corrosion, chemical degradation, fracture, and

deformation processes which lead to the breakdown of metals and ceramics

currently being utilized in pilot plants. Studies will also be carried

out on new candidate materials considered for improved performance.

Special emphasis will be devoted to the development of test methods,

especially short-time procedures, to evaluate the durability of materials

in the gasification environments. These methods will focus on wear,

impact erosion, stress corrosion, strength, deformation, slow crack

growth and chemical degradation. A system has been initiated to abstract

and compile all significant operating incidents from coal conversion plants

as well as materials property and performance information important to the

design and operation of these plants. This program will provide a central

information center where problems of common interest can be identified

and analyzed to avoid unnecessary failures and lead to the selection of

improved materials for coal conversion and utilization. Active consultation to DoE and associated contractors will be provided as requested.

II. SUMMARY OF PROGRESS TO DATE

Brief Summary

1. Metal Corrosion

a. Slow Strain Rate Test

A thorough metallographic examination of the alloy specimens tested in

helium, oxidizing/sulfidizing gas mixture, and oxidizing/sulf idizing/

carburizing gas mixture at 450 °C (840 °F)

,

and 600 °C (1100 °F) at a strain rate of 10 -o /s was completed. Of the six alloys tested, four

(Types 310 SS, 310S SS, nickel alloy 800, and nickel alloy 671) were

found to be susceptible to cracking at 600 °C by possibly different

mechanisms, however, all were detected by the slow strain rate technique.

A summary report is in progress of all the progress to date of the slow

strain rate testing technique. A preliminary evaluation was done on wedge-loaded DCB* specimens that were received from the Synthane plant.

These specimens were exposed in the liquid phase of the scrubber surge

tank. The preliminary evaluation showed that little, if any, cracking

occurred in any of the specimens during the exposure at 196 °C (385 °F)

.

Some design changes were made to the pulse echo ultrasonic equipment to

be purchased by NBS for in situ monitoring of the cracking progress of

specimens while they are being tested.

*Double cantilever beam.

1
A follow-up summary report will be submitted. We will complete the

evaluation of the DCB specimens exposed in the Synthane plant; install

NBS purchased resistivity equipment for in situ monitoring of the

cracking progress of specimens while they are being tested.

b. Pre-Cracked Fracture Test

A temperature compensated DCB test specimen has been developed for

conducting stress-corrosion tests in situ at elevated temperatures.

This specimen is independent of temperature. For example, a specimen

of 310 stainless steel would show a change of less than 4% in the stress

intensity on heating from room temperature to 700 °C.

2. Ceramic Deformation, Fracture and Erosion

A high-alumina (94%) refractory concrete was exposed to a simulated coal

gasification environment of gaseous H2 0, CO, CO , H2 and CH4 at temperatures of 510°, 710°, and 910 °C, and at a pressure of 7.5 MPa (^1090 psi)

.

Room temperature flextural strength did not seem to be affected by exposui

under these test conditions. In addition, the hot strength of a low-alumi

;

refractory concrete was measured both before and after hydrothermal treatment. An improvement in the hot strength on hydrothermal treatment was obtained throughout the useful temperature range of the refractory. The

construction and assembly of the high temperature, high-pressure mechanics ( loader has entered its final phase. All valving necessary for the operatic

of a pressure balancing unit which will regulate the pressure between the

inner containment vessel and the outer pressure vessel has been completed.

3. Chemical Degradation

a. Reactions and Transformations

Energy dispersive powder diffraction patterns obtained in two series of

experiments with high alumina neat cement bars heated in steam have been

interpreted by visual inspection using the reference patterns prepared

earlier. Computer methods developed during the past quarter to assist

in the interpretation have also been applied. During the next quarter,

the studies will be extended to include a lime-alumina-silica refractory

in steam and in a complex simulated gasification environment.

b. Slag Characterization

The high pressure viscometer is currently operational and preliminary

viscosity measurements have been made up to 95 psi steam pressure (at

1100 °C)

.

2

.
c. Vaporization and Chemical Transport

A new type of capillary sampling probe, suitable for corrosive slag

atmospheres, has been developed and tested on an alkali silicate system

where significant vapor transport of sodium-containing species was

found. Conditions whereby thermodynamic equilibrium is approached in

our reactor and with minimal perturbation by the sampling process have

been established for a conical probe. Thermodynamic equilibrium modeling

of vapor transport in slag-coal gas systems was initiated and sodium

vapor transport demonstrated theoretically.

The new sampling probe will be characterized for its ability to sample

equilibrium systems without perturbation. More detailed experimental

and modeling studies of slag-coal gas vapor transport will be carried

out.

4. Failure Prevention

a. Failure Information Data Center

Thirty-seven additional reports of operating experiences and failure

analysis were entered into the Center's data base. A detailed analysis

of the performance of materials and components at the C02 Acceptor

Process Plant was completed and a report is in preparation. Additional

progress was made on a similar report covering the Hygas Pilot Plant.

b. Materials Properties Data Center

The work of the Center has continued with the handling and cataloguing

of reports, the initiation of a thesaurus which will be needed at a later stage for computer file cataloguing and searching, further study

and planning for a suitable Data Base Management System, drawing up of

final specifications for the equipment for the computer-terminal facility,

the ordering of the first four pieces of equipment to establish the

facility, and the preparation and revision of summary report.

Articles Published and Talks Presented

J. H. Smith, "Operating Experiences with Incoloy 800 in Coal Conversion

Process Plants," a talk presented at the Petten International Conference - Alloy 800, Petten (N. H. ) , The Netherlands, March 1978.

G. M. Ugiansky and C. Johnson, "Slow Strain Rate Stress Corrosion Testing

of Metals in Gaseous Atmospheres at Elevated Temperatures," planned

(article under review) for publication in the Proceedings of ASTM

Sympsoium: Stress Corrosion Cracking—The Slow Strain Rate Technique,

May 2-4, 1977, Toronto, Canada.

S. M. Wiederhorn, "Erosion of Castable Refractories," Fourteenth Annual

Symposium on Refractories, sponsored by the American Ceramic Society,

St. Louis, Missouri, April 7, 1978.

3
III. DETAILED DESCRIPTION OF TECHNICAL PROGRESS

1. Metal Corrosion

a. Slow Strain Rate Test (G. M. Ugiansky and C. E. Johnson, 561)

Progress : A detailed report is being prepared on the Slow Strain Rate

Test for submission as a special report. The abstract of that report

is as follows:

A total of six different alloys — stainless steel (SS) Types 310,

310S, 347, and 446, and nickel alloys 800 and 671 — were tested using

the slow strain rate test technique in oxidizing/sulfidizing and in

oxidizing/suf idizing/carburizing simulated coal gasification environments,

and in helium (and other inert environments) at both 450° and 600 °C at a strain rate of 10~ s /s. Of the six alloys, four (Types 310 SS , 310S SS

,

nickel alloy 800, and nickel alloy 671) were found to be susceptible to

cracking at 600 °C by possibly different mechanisms, however, all were detected by the slow strain rate technique.

For cracking, the nickel alloy 671 required no reactive environment — it

suffered internal cracking in helium and all other test environments used.

However, the stainless steel Types 310, 310S, and nickel alloy 800, all

of which failed through surface initiated cracking, required increasingly

severe environments for cracking. The Type 310 SS required very little

reactive environment -- it cracked not only in the simulated coal gasification gases but also in low vapor pressure Oa and/or H 2 O environments (foi

example, helium), as did the 310S SS, although with greater ductility than

the Type 310 SS. The nickel alloy 800 required the rather reactive

environment of the simulated coal gasification gases — it did not crack

in the low vapor pressure O 2 and/or H 2 O environments.

The detection of the environmentally independent failure of alloy 671

shows that the use of the slow strain rate technique need not be limited

to use for testing for susceptibility to cracking by stress corrosion

cracking. The slow strain rate technique is shown to be a viable testing

method for detecting an alloy's propensity to premature failure in gaseous

simulated coal gasification environments.

During this quarter, the testing of stainless steel alloys Types 310,

310S, 347, 446, and nickel alloys 800 and 671 has been completed in the

oxidizing/sulf idizing (previously called oxidizing) and in the oxidizing/

sulf idizing/carburizing (previously called reducing) coal gasification

environments and in an inert gas environment (ultra-pure He) at 450 °C

and 600 °C at a strain rate of 10_s /s. The compositions of the simulated

coal gasification gases are shown in Table 1. The major difference betweer

the two mixtures is the deposition of carbon from the oxidizing/sulfidizinc

carburizing gas at both temperatures, the oxidizing and sulf idizing potenti

being similar when comparing the two mixtures at the same temperature.

4
Metallographic examinations of the tested alloy specimens have been

completed and a thorough summary report (soon to follow) of all results

and their significance is currently being prepared. In brief, the

results show that of the six alloys tested, at 600 °C four (Type 310 SS

,

Type 310S SS, and nickel alloys 800 and 671) were found to be susceptible

to intergranular cracking. Two of the alloys (Type 310 SS and nickel alloy

671) failed with relatively low ductility compared to the other two alloys

(Type 310 S SS axid nickel alloy 800) when tested at 600 °C. None of the

alloys cracked when tested at 450 °C in either of the coal gasification

environments or in He. In earlier tests, it was noted that Type 310S SS

did not show any susceptibility to cracking when tested at 540 °C, but the

increase in temperature to 600 °C resulted in cracking of the Type 310S SS

The Type 310S SS, with the lower carbon content than Type 310 SS , has to be

subjected to a higher temperature or a longer time at temperature for

sensitization and, therefore, cracking to occur. The alloy compositions

can be found in Table 2. The reported cracking failures were possibly due

to different mechanisms, however, all were detected by the slow strain rate

technique. The specific environmental conditions needed for cracking of

the above mentioned four alloys are summarized in Table 3. The detection

of the failure of nickel alloy 671 by an internal cracking mechanism shows

that the use of the slow strain rate technique need not be limited to use

for testing for susceptibility to cracking by stress corrosion cracking (SCC)

Some of our wedge-loaded DCB specimens exposed in the Synthane plant have

been received. These specimens were from the liquid phase scrubber surge

tank with the liquid effluent summarized in Table 4. The specimens were

Types 304 SS , 309 SS, 310 SS, 446 SS, nickel alloy 800, nickel alloy 671,

and low carbon steel AISI 1018-20. The specimens were exposed for a combined time of 2046 hours (592 hours operating time and 1454 hours

standby time) at an average operating temperature of 196 °C (835 °F) and

a pressure of 600 psig. The as-received exposure rack is shown in Fig. 1.

One of the exposed specimens is shown in Fig. 2. Preliminary evaluation

of the specimens (i.e., measurement of the crack growth without splitting

apart of the specimen) shows that little, if any, crack growth occurred during

testing on any of the specimens. After the exposure, the specimens were

coated and pre-cracked areas were packed full with a solid deposit (Fig. 2).

Further evaluation of these specimens by splitting them apart and measuring

the crack length will be done.

Some design changes are being made in the pulse echo ultrasonic equipment

to be purchased by NBS for in situ monitoring of the cracking progress of

specimens while they are being tested.

Plans : Submit follow-up summary report. Finish evaluation of the DCB

specimens exposed in the Synthane plant. Install NBS purchased resistivity

equipment for in situ monitoring of the cracking progress of specimens

while they are being tested.

5
TABLE 1 GAS COMPOSITIONS

1 '

(Vol . %)

Oxidizing/Sulfidi zing C-as (2) Oxidizing ./Sul fidi zing /Carburizi

INPUT EQUILIBRIUM

I INPUT EQUILIBRIA'

latm, 25°

C

latm, 450°C latm, 600°C latm, 25°

C

latm, 450°

C

la t

CO 11.6 1.2 9.2 26.0 1.1

C0

2 15.4 24.9 20.6 14.8 22.0

II

11 9«_ 13.0 16.0 36.3 26.0 12.8

CH

4

10.0 12.5 2.9 10.0 11.2

H ? S 1.0 1.0 0.9 1.0 1.0

h

2 o 49.0 44.4 30.3 22.2 34.3

C - - - - 17.6

log s

-28.995 -23.919

• -29.026

log p h

-10.260 -8.878 -10.086

log a

c “0.043 -0.288 +0.017

Footnotes

(1) The gas mixtures are two of twelve mixtures being used at Battelle

Columbus Laboratories and Argonne National Laboratory.

(2) This mixture corresponds to Battelle' s "Gas Mixture 1A." [7]

(3) This mixture corresponds to Battelle' s "Gas Mixture 3A." [7]

Note: The major difference between the two mixtures is the deposition of

carbon from the oxidizing/sulfidizing/carburizing gas at both

temperatures, the oxidizing and sulfidizing potentials being

similar at each temperature.

6
7
8
Table 4

Liquid Effluent from Scrubber

Surge Tank

Phenols (ppm)

Chemical Oxygen Demand (ppm)

p-Alkalinity (gms/gal)

m-Alkalinity (gms/gal)

N as NH 3 (ppm)

S (ppm)

Chlorine (ppm)

Dissolved Solids (ppm)

Thiocyanate (ppm)

Cyanide (ppm)

pH

Total Suspended Solids (weight %)

0-12,500

100-71100

0-77

0-743

0-4410

5-346

95-153

50-2100

No Data

No Data

5 . 2-9 c 5 0-67
Fig. 1. Wedge-loaded DCB specimen exposure rack from the liquid

phase of the scrubber surge tank from the Synthane plant.

10
Fig. 2.

J

Wedge-loaded DCB specimen from the liquid phase of the

scrubber surge tank after 2046 hours at an average

temperature of 196°C (385°F)

11
b. Pre-Cracked Fracture Test (J. H. Smith, 562.00)

Progress : A tension-loaded, double cantilever beam specimen has been

designed for conducting elevated temperature stress-corrosion tests.

This specimen is a modification of the wedge-loaded double cantilever

beam specimen which is extensively used for stress corrosion testing

at ambient temperature.^ The susceptibility to stress-corrosion

cracking is expressed in terms of the stress intensity factor, K . The

crack growth rate, da/dt, due to stress-corrosion cracking is proportional

to the stress-intensity, Kj , and the minimum stress-intensity value

below which crack propagation is not observed is designated as K

ISCC

* Both the commonly used wedge-loaded double cantilever beam specimen

and the newly designed tension-loaded double cantilever beam specimen

have the advantage, for stress-corrosion testing, that the applied

stress-intensity, , decreases as crack growth occurs so that in

principle, the minimum stress-intensity value below which crack growth

will occur, that is K

ISCC ' can determined with a single test specimen.

If the dimensions of the double cantilever beam specimen. Figure 1, are chosen such that the length of the specimen W >. a + 2H, where ’a 1 is

the crack length and 2H is the specimen height, the stress intensity, K , calibration for the specimen is independent of the uncracked ligament in

the specimen, (W-a) , and the stress intensity for the specimen is:^

K

i - 375 [3 ' 46 + 2 - 38 f

1 Dn

where

P - applied load

a - crack length

B - specimen thickness

H - specimen height

For a specimen that is loaded by displacement control instead of load

control, the load, P, is related to the displacement, V, at the loading

point by the relationship:

p = EBV

7.97 (f)

3 + 16.48 (J)

2 + 11.32 <J) H ri ri where E is the elastic modulus of the specimen.

By combining equations [1] and [2] the stress intensity is given in

terms of the displacement as:

_ EV 3.46 + 2.38 (|) K

j “ H

> J 7.97 (Jr + 16.48 (J) + 11.32

n H

12
This equation is applicable to a double cantilever beam specimen loaded

to a specified displacement, V, under the following conditions:

W = a + 2H

2 1 f 1 10

K

I 2 a > 2.5 (—

)

- ay

where ay is the yield strength of the specimen material.

Equation (3) is used as the basis for designing a double cantilever

beam specimen that can be loaded to a specified level at room

temperature and used for testing at elevated temperature without

a substantial change in the initial applied stress intensity level,

Kj , due to the change in temperature. Once crack growth starts due

to stress corrosion cracking at the elevated temperature, the stress

intensity decreases with crack growth until the level is reached

according to equation (3)

The tension- loaded double cantilever beam specimen, shown in Figure 2, was designed to be independent of testing temperature. Equation (3)

shows that the stress intensity, K^, is directly proportional to the

elastic modulus of the test specimen, E, and the applied displacement,

V, and to a function of the crack length, a, to specimen height, H,

ratio, a/H. Only the elastic modulus, E, and the applied displacement,

V, change significantly with temperature. Therefore, the ratio of

the stress intensity at a specified temperature, Km , to the stress

intensity at a reference temperature, such as room temperature, K is

given as:

K.KE V

T T

E V

' 0 0

where E^ and are the elastic modulus and applied displacement at the

specified temperature, T, and E„ and are the modulus and displacement

at the reference temperature, T .

The tension-loaded double cantilever beam specimen. Figure 2, is designed

so that thermal expansion of the loading fixture on increasing

temperature will nearly balance the decrease in elastic modulus with

increasing temperature so that the ratio

K

K

1 . 0 .

13
1.0

,

. K E V That is, IT T T

K.10E V

0 0

The change in elastic modulus, E with temperature has been determined

for all common alloys. In general, the modulus of elasticity of

common alloys decreases approximately linearly with temperature up to

relatively high temperatures beyond which a sharp drop in modulus

occurs. For example, austenitic stainless steels and Ni-Cr-Fe alloys

such as Incoloys show a linear decrease in modulus with increasing

temperature up to approximately 1300°F (704°C).( 2 ) Therefore, the

change in elastic modulus with temperature can be expressed as: E

t

= Eq - m (T - T ) where m is an empirically determined

coefficient. For example, up to 700°C (1300°F) stainless steel

alloys follow the relationship E = E^ - 11.0 x 10 2 (T - T ) where E

is in units of psi and T is °C. (?) 0 0

The applied displacement, V, at the loading point of the DCB specimen

can be made to either increase or decrease as the temperature increases.

The initial displacement, , is applied mechanically on loading the

specimen at room temperature. The displacement, V , at the elevated

temperature, T, is controlled by the difference in thermal expansion

between the specimen and loading fixtures. The change in stressintensity with increase in temperature is given by the following

expression

k ( a - a - a ) __T _ , _ mT T , F T , S T , G . K ^ E

^ 1 V

0 0 o

where

- stress-intensity of the specimen at test temperature, T.

Kq - stress-intensity of the specimen at reference (loading) temperature,

m - temperature coefficient of the elastic modulus of the specimen.

E

q - elastic modulus of the specimen at reference temperature T .

T - test temperature of interest.

V

Q

- initial displacement of the specimen at temperature T

Q

.

H - length of loading frame at temperature T (see Figure 2) T , F

H - length of specimen at temperature T. I/O

H - length of specimen grips at temperature T. T / G

l T,F - Vf 11 + a

F

(T - V ]

14
where Z q ^ is the length of the loading frame at temperature T

Q

and

a is the linear coefficient of thermal expansion from T to T. F 0

Similarly: £ _ = _ [1 + a (T - T ) T , S 0,S L S 0

£ = £„ [1 + a (T - T ) ] T, G 0 , G

L G 0J

for the specimen and loading grips, respectively.

In general the loading frame will be constructed of different material

than either the specimen or the loading grips. By carefully choosing

the combination of materials in the specimen, loading grips, and loading

fixture, the specimen can be made temperature compensating, that is,

k

t —— = 1.0 regardless of temperature. As the specimen is loaded to

K

o different initial displacements, V , the length of the loading grips,

g

, must be changed to permit K

t

to be independent of temperature.

This is the reason for the specimen loading fixture being designed

as a form of " turnbuckle.

To demonstrate that the tension loaded double cantilever beam specimen

can be made thermally compensating, a loading fixture made of 18-8

type stainless steel with a specimen of type 310 stainless steel and

adjustable grips made of Monel was designed and analyzed. Figure 3 shows a plot of K^/K^ versus temperature up to 730°C (1350°F) for this

specimen configuration. This shows that no decrease in K with

temperature is expected up to approximately 550°C (1000°F) and that

up to 730°C (1350°F) the decrease in is only about 4% from the

original "as-loaded" K level. By contrast, a wedge loaded double

cantilever beam specimen cannot be made temperature compensating and

the level at 730°C (1350°F) would decrease to approximately 70% of

the "as-loaded," room temperature value, as shown in Figure 3.

Ref.

1. B. F. Brown, "Stress-Corrosion Cracking in High Strength Steels,

Titanium, and Aluminum," Naval Research Lab., 1972, Chap. 2.

2. F. Garofalo, P. R. Malonvek, G. V. Smith, "The Influence of

Temperature on the Elastic Constants of Some Commercial Steels,"

ASTM, STP-129 , 1952.

Plans ; Plans for the next quarter are to:

1. Complete stress analysis for the tension-loaded double cantilever

beam specimen. This is to include calculation of creep strains and a limited sensitivity analysis.

2 . Calculation of T versus temperature for various test materials of

interest and various K levle.s

0

15
3. Experimental verification of the — equation by measurements of

i

• K

° specimen compliance.

4. Procurement of selected alloys and specimen preparation for

preliminary laboratory tests.

16
17

Design

of

Double-Cantilever

Beam

Specimen
%

GRIPS

Figure 2

Tension - Loaded DCB Specimen

18

n

.fl

fnrmn-g,^^,

h-hh

1

1

^‘iothwi

iiiinM!

n

imn<

ii

iii

n

^
T7
(E. R. Fuller

,

Jr. , S. M. Wiederhorn

,

J. M. Bukowski , and

D. E. Roberts

,

562,

C. R. Robbins

,

565)

Progress: Exposure studies on a high-alumina (94%) refractory concrete

in a simulated coal gasification environment were continued this past

quarter. The ambient gas mixture for these studies was 40% H 2 O, 20% CO,

15% CO 2 , and 25% H 2 (Vol. %) , which gives a gaseous environment of H 2 0,

CO, CO 2 , H 2 and CH 4 at the temperature-pressure exposure condition. In

this series of exposures, pre-fired* refractory concrete specimens were

initially heated to the exposure temperature in an argon environment at

atmospheric pressure. Once temperature equilibrium was reached, H 2 0 and

a mixture of gaseous H 2 , CO, and CO 2 were metered into the exposure

vessel. Refractory samples were exposed to these simulated gasification

environments at temperatures of 510°, 710°, 910 °C, and at a pressure of

7.5 MPa (^1090 psi) . After an exposure period of 90 hours, the specimens

were allowed to cool to 500 °C at which point the exposure environment

was slowly vented before cooling to room temperature. Room temperature

flexural strength did not seem to be affected by exposure under these

test conditions (Table 1) . The determination of the mineralogical

properties of the exposed high-alumina refractory concretes in progress.

Table 1

Control

(Air-fired to 1010°C)

I

14.

8 (+1.8) MPa

2 , 150 (+260) psi

TEMPERATURE

510°C 710°C 910°C

13.4 (+2.4)MPa 16 . 1 (+0 . 4) MPa 14. 8 (+1 )

1 , 950 (+340 ) psi 2 , 340 (+60 ) psi 2,150(-

In addition to these exposure studies, the hot strength of a low-alumina

(56%) refractory concrete has been measured both before and after hydrothermal treatment. Specimens treated hydrothermally were heated in a saturated H 2 O environment to 310 °C and held for 65 hours at a pressure

of 9.9 MPa (1430 psi). The temperature was then increased to 610 °C with

the steam pressure being bled to maintain a constant 15.0 MPa (2180 psi).

The refractory concrete specimens were held at temperature and pressure

for 160 hours. On cool down, the steam pressure was slowly vented at

*1010 °C for 5 hours

**4 specimens tested at each condition

20
500 °C. The specimens were broken on a commercial testing machine using

a constant cross-head speed of 5 x 10

-3

cm/min. All specimens were heated

at approximately 5 °C/min, and were allowed to soak at the test temperature

for 15 hours before breaking.

Our previous studies on both a commercial composition and a laboratoryprepared composition of a low-alumina refractory concrete indicated that

under certain conditions an increase in room temperature flexural

strength and erosion resistance is obtained. The present studies examine

this improvement in mechanical properties at elevated temperatures. The

hot flexural strength of a hydrothermally exposed, low-alumina refractory

was increased throughout the useful temperature range of the refractory

(Figure 1) . X-ray diffraction analysis indicates that the improved

mechanical properties are related to the reaction of free silica, con- tained in the aggregate, with the calcium aluminate phases in the cement

to form anorthite (CAS 2 )*. The anorthite phase forms a strong, continuous

structure of small crystallites that permeates and binds the refractory

matrix. A determination of the hot erosive wear properties of this

hydrothermally treated concrete is presently in progress. Since the

room temperature erosion behavior after hydrothermal exposure seems to

be controlled by the ' same microstructural properties that influence

strength, an increase in the hot strength is also expected to increase

the hot erosion resistance.

Compressive strength measurements were made on refractory concrete

samples obtained from the CO2 Acceptor Plant. In some cases, the lowalumina refractory concrete used at the hot face exhibited a compressive

strength 2 to 3 times greater than air-fired laboratory specimens. Xray diffraction analysis showed the presence of well crystallized

anorthite to be present in the refractory samples obtained from the CO2 Acceptor Plant. As in the hydrothermally treated refractory concretes,

it is the formation of this anorthite that accounts for the increase in the

compressive strength. A complete analysis of the examination will be

published in a separate N.B.S. publication for the Department of Energy.

In addition, a mineralogical and microstructural analysis is in progress

for refractory concrete specimens exposed in the Synthane Process Pilot

Plant

The construction and assembly of the high- temperature , high pressure,

mechanical loader has entered its final phase. All plumbing and valving

necessary for operation of the pressure-balancing system of the mechanical

loader has been completed. Presently, the electronic control system is

being assembled and installed. This system is required to maintain a pressure equilibrium (AP=0) between the inner containment vessel and

outer pressure shell. On satisfactory installation and check out of the

pressure balancing system, the mechanical loader will be operational,

and systematic testing of refractory concretes will begin.

Cement Chemistry Notation: C = CaO , S = SiC> 2 , H = H2 O, A = AI 2 O 3

21
Plans: In the next quarter, assembly of the apparatus for mechanical

testing at elevated temperatures and pressures should be completed. The

total system will then be checked out under controlled experimental

conditions. These experiments should establish the operation of the

apparatus by the end of the quarter. Studies will then commence on refractory concretes under hydrothermal conditions.

Mechanical property studies at room temperature will continue on high

and low-alumina refractory concretes after exposure to simulated coal

gasification environments. After completion of the studies using a five

component gasification environment (H2O, CO, CO2 , H2 r and CH4), more

elementary studies will be conducted using two and three component gaseous

systems such as H2O, CO, and CO2 and H2O and H2 •

22
1130

1310

1490

1670

1850

2030

2210

2390

(psi)

r- CN (—1 is rH ID o

(N o O' LO CN o P* in LO

ln CO o m >D <Xi 1—1 rr CN

lD in in S m CN CN rH r- - y

- £" ’ -y- r V

(BdW) q}6ua^s TBanxau goH

o

o

(1)

S-l DP

rdU

<D£

<D

E-i

23

Figure

1.

Hot

flexural

strength

of

a

low-alumina

(56%)

refractory

concrete

before

and

after

hydrothermal

treatment.
3. Chemical Degradation of Ceramics

a. Reactions and Transformations (F. A. Mauer and C. R. Robbins, 565)

Progress : Two series of experiments using cast bars of high alumina

neat cement have been carried out in a steam atmosphere. A third test

of the neat cement in steam is underway. Although the primary purpose

of the first two experiments was to test the performance of the apparatus, useful chemical information was obtained. All phase assemblages

have been identified by visual inspection with the aid of the standard

reference patterns prepared earlier and published in quarterly progress

reports for Jan. -Mar. 1977 and Apr. -June 1977. Computer programs have

also been prepared to assist in the analysis of patterns.

The first series of experiments was carried out using a bar of high

alumina neat cement dried at 110°C and fired at 1010°C (specimen #2)

.

This specimen, which consisted of CA2

* with small amounts of CA and

01 -AI 2 O 3 was heated for 12 days in steam. The results are summarized in

Table 1. Major changes are seen in the relative amoungs of CA2 C 3 AH0 , C 4 A 3 H 3 , AH, and 01 -AI 2 O 3

. Although CA2 , C 3AH5 , and C 4A 3 H 3 are usually considered to be the bonding phases of high alumina castable

refractories, there is considerable interest in the role of AH because

of earlier work by Fuller, Robbins, and Loeb 1 showing that the dissociation of this phase is associated with a dramatic loss in strength.

Table 1 shows that changes begin at temperatures as low as 93 °C.

After 20 hours of exposure at 93 °C, CA2 was still the principal crystalline phase but the loss in intensity suggests that hydrates were

forming which were not sufficiently well crystallized to give good

diffraction patterns. As a result, C 3 AH0 and AH 3 appeared only as minor

constituents. At 110°C after 46 additional hours of exposure only trace

amounts of CA2 remained. AH formed rapidly at 210°C but remained poorly

crystalline after 4 hours. Crystallinity improved during the next 3 hours, and after 22 hours the test bar consisted of well crystallized

C 3AH0 and AH. After 15 hours at 365°C and 7.7 mPa,^ C 4A 3H 3 and AH were

the major phases with minor amounts of 01 -AI 2 O 3

.

The dissociation of the bonding phase, AH, and formation of CX-AI 2 O 3 was observed at 410°C and 7.9 mPa. This reaction proceeded slowly and

AH was still a major phase after 24 hours. Even after 3 hours at 450°C

and 7.9 mPa (a temperature that is approximately 100°C above its reported

"equilibrium" region) , AH was a major phase. Dissociation of the remaining AH occurred rapidly at 475 °C and 7.9 mPa while CA2 and CA began to

form from C 4 A 3 H 3 and AI 2 O 3

. The amount of CA2 increased during 16 hours

*Cement Chemistry Notation: C = CaO, S = SiC>2 , H = H2O, A = AI2O3 .

1 Quarterly Progress Report FE 1749-6, December 1975.

“In SI Units p(mPa) = p(psig) + 14.7

145

24
at 475 °C and 3 hours at 500 °C. Growth of the bonding phase, CA2 , at

the expense of CA and C1 -AI 2 O 3 proceeded slowly over the next 6 hours at

550°C and 575°C. At 600°C and 7.2 mPa the rate of formation of CA 2 appeared to increase significantly. The reaction was essentially com- pleted after 18 hours. The phase assemblage CA2 (major phase) and

a-Al 20(minor phase) that resulted was observed at all temperatures and

pressures up to 1000 °C and 7 mPa. These observations suggest that, with

the development of the CA2 phase above 600 °C, a high-alumina castable

may regain some of the strength lost because of the dissociation of

C 4 A 3 H 3 and AH.

The series of experiments with specimen #3 (high alumina neat cement

dried at 110°C and fired at 1010°C) were carried out in steam over a 19

day period, and reached a maximum temperature of 995 °C at 7 mPa.

The results are of interest because the inadvertent use of a silica containing cement to secure the test bar in the pressure vessel

subjected the specimen to an environment of SiC>2 dissolved in the vapor

phase. As shown by in situ x-ray diffraction analysis, the hydration

sequence continued normally until the assemblage C 3AH6 + AH was obtained

at 210°C and 2 mPa. These conditions were maintained for 72 hours,

after which it was observed that the calcium aluminate-steam reaction

had been suppressed. Examination of the test bar showed the presence of

a reaction rim ^0.7mm thick, composed mainly of C 2 AS, 8 -CS, CA 2 , and

CX-AI 2 O 3

. The silica had been dissolved from the cement by the steam and

then transported to the surface of the test bar where it quickly reacted,

forming calcium silicates and calcium aluminum silicates. Since silica

impurities in coal would be expected to contribute dissolved silica to

the pressurized steam of a gasification reactor, similar reactions

between dissolved silica and an initially high purity calcium aluminate

castable can be expected to occur.

The early stages of the hydration of specimen #3 of high alumina neat

cement are shown in Fig. 1 to demonstrate the use of difference plots

in the interpretation of patterns. Pattern No. 11 at the top of the

figure was recorded at 207 °C and 1.5 mPa after gradually increasing the

temperature over a 24 hour period. Pattern No. 2 was recorded at room

temperature. In the difference plot, the negative peaks all correspond

to CA2 , meaning that this is the phase being consumed. The positive

peaks correspond to AH and C 3AH0 , the products of the reaction. Difference plots have been prepared for several critical temperature ranges.

They are particularly useful in showing which phases are involved in

reactions and in distinguishing the reaction products from the phase or phases being consumed.

Plans : Data obtained from the high purity neat cement now being heated

in steam will be analyzed, after which the same material will be tested

in more complex atmospheres. A lime-alumina-silica refractory will also

be examined by in situ x-ray diffraction, first in a steam atmosphere

and then in a simulated gasification environment.

25
i~i I « fs

Lj n H

Figure 1. EDXD patterns for specimen #3 of high alumina neat cement heated

in steam. The difference pattern formed by subtracting No. 2 from No. 11 shows

the loss of CA2 (negative peaks) on reaction with steam to form AH and C 3AH 0 (positive peaks)

.

26
TABLE 1 # 1.7 SITU X-RAY ANALYSIS OF HIGH ALUMINA NEAT CEMENT SPECIMEN *2 IN STEAM

Temperature

(°C) Pressure

(psig)

Time

(hr) X-ray Analysis and Remarks

25 0 CA2 , small amounts a-Al 2 03 , CA

93 M.0 20 CA2 major phase but intensities greatly reduced,

C 3AH5 and AK 3 present as minor phases

110 VL5 46 C 3AH5 , AH 3 , AH, a-Al 20 3 , trace CA2

210 200 4 C 3AH 5 , AH major phases, trace oc-Al 20 3

210 150 3 C 3AH5 , AH. Crystallinity of AH improving

210 150 15 C 3 AH5 , AH. Well crystallized

210 150 7 C 3AH 6 , AH, major phases, a-Al203 minor phase

100 15 3 C 3AH5 , AH, major phases, ct-Ai ?03 minor phase

365 1100 15 C 4 A 3 K 3 , AH, major phases, a-Al 203 minor phase

310 970 6 C 4A 3 H 3 , AH major phases, a-Al 2 0? minor phase

410 1130 2 C 4A 3 H 3 , AH major phases, a-Al 203 minor phase

410 1120 14 CuA 3H2 ,a-Al 203 , AH major phases. AH dissociating

410 1120 8 C 4A 3 H 3 , a-Al 203 , AH major phases. AH dissociating,

a-Al 2 03 forming

450 1130 1 ditto

450 1130 1 ditto

450 1130 1 ditto

475 ’ 1130 1 CA 2 , CA, C 4A 3 K 3 , a-Al2 03 major phases, trace of AK

475 1130 15 CA2 , CA, C 4A 3H 3 , a-Al2

C>3 major phases. CA2 increasing

500 1075 3 CA?, CA, C 4A 3 K 3 , ot-Al?0 3 major phases. CA2 increasing

550 1100 4 CA2 , CA, a-Al 2 03 major phases. CA? increasing

575 1100 22 CA 2 , CA, a-Al 2 03 major phases

600 1030 1 CA 2 , CA, a-Al?0 3 major phases. CA? increasing at the expense of Al203 , CA

600 1030 3 ditto

600 1050 15 CA2 major phase, ct-Al 2

C>3 minor phase

700 1000 3 ditto

800 1000 16 CA?, trace a-Al 203

900 1060 1 ditto

1000 1000 1 ditto

*in SI units - 1 mPa =145 psia

27
b. Slag Characterization (W. S. Brower, J. L. Waring, D. H. Blackburn

and C. A. Harding, 565)

Progress: The high pressure viscometer is currently operational. In

the present design the temperature of the rotating crucible (Figure 1,

letter I) cannot be measured directly. Therefore a calibration between

the melt crucible and the platinum heater (Figure 1, letter F) temperature

must be established. This calibration is performed by inserting a thermocouple into the molten slag and measuring the temperature; concurrently, a separate thermocouple welded on the platinum heater is monitored. The

results of the calibration are given in Figure 2. As might be expected,

a linear relationship exists between the temperature of the crucible and tl temperature of the platinum heater at various pressures.

An iron silicate slag with low melting characteristics was selected for

initial viscosity measurements. The composition is as follows: Si02

42 wt%, AI 2 O3 3 wt%, Fe 2 C>3 25 Wt%, CaO 5 wt%, MgO 5 wt%, Na 2 0 15 wt%,

K2 0 5 wt%. Other iron silicates might be expected to exhibit similar

behavior in steam pressures.

The results of the preliminary viscosity measurements are given in

Figure 3. In the figure, logi 0 n (viscosity in poises) is plotted

against temperature in degrees C. Curve A represents the viscosity at

various temperatures and ambient pressure. Similarity curves B, C, D

represent viscosity as a function of temperature at pressures of 60 psi,

80 psi and 95 psi steam respectively.

The glass which was heated previously in steam (Fig. 3, curve C) was reheated at ambient pressure to outgas the included water vapor, then

the viscosity was remeasured at ambient pressure. These results are shown in Figure 4; it can be seen that the viscosity has only increased

slightly. The increase may be due to loss of alkali because of added

and prolonged heat treatment or it may have been associated with the

steam treatment. The composition was unusually high in Na 2 0, loss of

which would be expected to raise the viscosity. Loss of K 2 0, would have

the opposite effect but its volatility is less as well as its concentratioi

Samples were taken from two slags which were quenched in air and steam

respectively, to form glass and these were reheated at atmospheric pressurt

in air and the weight loss determined. The slag which had never been

subjected to a steam atmosphere showed a weight loss of 0.03% at 1200 °C

after 18 hours. A sample of the same slag subjected to 80 psi steam

pressure at 1175 °C for about four hours, and quenched, showed a weight

loss of 0.62% for the same conditions. Under these conditions, the slag

did not achieve a constant weight, indicating further weight losses would

be observed if held at temperature or longer time.

*ln SI Units p (MPa) = P(pS h>

- 14 • 7

28

l
It can be noted from Figure 3, that the viscosity of this silicate melt

appears to increase significantly with increasing steam pressure at

constant temperature. This result is so unexpected that before these

data can be completely believed, the experiment must be repeated. Figure

4 illustrates that no appreciable composition deviation has taken place

in the slag. These experiments will be re-run in an attempt to determine

whether or not the present data are valid.

After the last run at 95 psi, the pressure vessel was opened and inspected.

The stainless steel interior was found to be slightly corroded and the

refractory bricks surrounding the platinum heater were severely attacked.

In addition, dendrites which appeared to be metallic copper had grown from

the electrodes; water used to generate the steam in the bottom of

the vessel was found to have a pH of about 3.2.

Plans : Several important modifications are currently being worked on to

improve the capabilities of this apparatus. A new shaft is being prepared

to hold the rotating crucible. This will be hollow so that a permanent

thermocouple can be inserted to measure the crucible temperature directly.

Other modifications will be made in the insulation and radiant heat

reflector design in an attempt to cut down the large heat losses, which

at the present, limit the temperature capability.
r

Figure 1. Full assembly schematic drawing of high pressure-temperature

viscometer

.

A - position detector

B - magnet

C - torsion wire

D - water condensation shields

E - electrodes

F - heating elements

G - temperature control thermocouple

- bob

- crucible

J - molten slag

K - spindle

L - anti-convection baffle

M - heat exchangers

N - bayonet heaters

0 - shaft seal

P - shaft cooling jacket

Q

- shaft bearing

H R - shaft drive mechanism

I 30
260

uU. cfl

£33

4~J cd

s*H

P-i

cd

t-i QJPcB

0) H

Oo

04

17 I

31

Figure

2.

Calibration

of

heater

temperature

vs

melt

temperature „
.

Figure

3.

Log

viscosity

vs

temperature

for

slag.
oo

CL» s-3

+->

<T3 U

<DClE

<D

OOo

ID

CM O

CM

(sasiod) >C;lsodsla 6o[

Figure

4.

Viscosity

of

slag

prior

to

steam

treatment

(A)

and

after

exposure

to

80

psi

steam

(3).
c. Vaporization and Chemical Transport (J. Hastie and D. Bonnell, 561)

Progress: Probe Development

.

The source of the problem of low beam

intensities encountered with the reactor-mass spectrometer system during

the previous quarterly reporting period has been identified. We have

established that the reactor alignment is satisfactory but the beam is

scattered by gas effusing through a micro crack in the reactor nozzle.

This crack apparently developed as the result of chemical corrosion and we have modified the reactor design to reduce this effect.

Two new reactor sampling nozzle designs have been developed, the first

having basically the same conical geometry as the original but with

thicker walls to increase resistance to corrosion. The second nozzle

utilizes a capillary tube rather than a thin walled cone as the gas

probe. The major fundamental difference between these two types of

sampling nozzle is that the capillary probe allows sample wall-gas

collisions to occur as the gas passes through the sampler from the

high-pressure reaction zone to the low pressure region of the mass spectrometer system. However, this effect has the advantage of reducing

the rate of gas flow into the vacuum chamber and thereby allowing higher

reactor pressures to be utilized by a factor of about two. The constructed

capillary is essentially a 1.9 cm long thick-wall platinum tube

with an average inner diameter of about .01 cm. This probe has been

tested, as described below, in an alkali silicate corrosive slag-like

atmosphere without incurring problems such as orifice plugging or enlargement due to corrosion. Thus for corrosive samples, this type of probe

should be more satisfactory than the prototype thin wall nozzle design

used previously. However, we should stress that such a probe should

only be used for equilibrium systems since the wall collisions would

disturb the composition of a kinetically controlled system. The less

robust conical-type sampling nozzle will be used for non-equilibrium

systems if necessary.

Reactor Equilibrium and Sampling Fidelity . As we have stressed in

previous reports, it is important to determine the range of pressure,

composition and temperature conditions for which the reactor attains

an equilibrium condition and for which the sampling process does not

perturb the equilibrium. We have previously shown, using the NaaSOi*

and NaCl test cases, that the vaporization processes have the expected

enthalpy changes for an equilibrium process over a wide temperature

interval. What remained to be established was the effect of reactant

partial pressure on the apparent equilibrium constant, if any. The

calibration salt Na 2 SOt+ was used for this test. By adding an external

source of SO2 to the N 2 carrier gas we were able to test the reversibility

of the process:

Na 2 SC>4 (£) = 2Na + 0 2 + S02 (K = pNa 2

• p02 * pS02 ) ]? under isothermal conditions at temperatures of around 1200 °C and total

pressures in the region of 0.5 - 0.7 atm. The apparent equilibrium

constant , for this process was observed to be pressure independent,

1

34
as expected for a non-perturbed equilibrium process, for S0 2 partial

pressures in the range of 10~"- 10

-2

atm, as shown in Figure 1. The

average value of K over the pressure independent interval was found

to be in good agreement with the expected literature value, as indicated

in Figure 1. However, at both lower and high S0 2 pressures K varied.

We believe that for relatively high pressures of reactant gas^(S02 in this

case) , some of the gas passes through the reactor into the mass spectrometer system without having contacted the sample. Hence, the observed S0 2 signal would be higher than the equilibrium level and correspondingly so would K . Based on these observations, we have decided to introduce baffles

into thl reactor to increase the number of gas-sample collisions prior to

sampling. This should increase the range of reactant pressures where

equilibrium can be established.

Alkali Silicate Vaporization . High pressure (0.7 atm N2 ) mass spectrometric analyses of the vapors over an alkali silicate oxide mixture of

composition: Si02 (75 wt %) , Na 2 0 (15.6), CaO (10) and S0 2 (0.4), plus

minor amounts of HCl, H 2 0 and hydrocarbon impurities were made using the

newly developed capillary probe. Nitrogen was used as the high pressure

transport gas. Vapor species were observed over the temperature interval

1100 - 1250 °C and typical mass spectral data are shown in Figure 2. Not

all the observed mass spectral ions were attributable to known molecular

species. The identifiable molecular precursors of interest included Na,

S02 , HCl, 0 2 and H 2 0. Some of the unassigned peaks may be new Na-containing

species whose identity can only be speculated on pending further study where

the reactive gas pressures are varied isothermally . The observed HCl and

H 2 O components were formed from impurities contained in the oxide sample.

Under the present conditions, the partial pressure of Na-containing species

is of the order of 10~ 6 atm which is sufficient to result in transport and

deposition of corrosive alkali deposits under expected coal gasification

conditions. It will be of interest to determine in future planned studies

the effect of reactive coal-gas atmospheric components on this alkali

transport. However, the complexity of the observed mass spectra for this

relatively simple system and the number of unassignable ion peaks reinforce our original expectation about proceeding with simple systems of

gradually increasing complexity prior to analyzing actual coal slag-coal

gas systems.

Thermodynamic Modeling of Slag-Coal Gas Interaction . During the past

Quarter we initiated the modeling phase of our program. As was indicated

in the original project proposal, sophisticated computer based modeling

will be used to provide the necessary link between laboratory results and

actual coal gasifier field data. A valid model should allow us to extrapolate the laboratory results of coal gas-slag-ceramic vapor transport

obtained at relatively low pressures of about 1 atm to actual gasifier

conditions of typically 20 atm. In the near term the modeling will be

limited to equilibrium systems and will be used primarily as a guide to

35
the selection and interpretation of experimental systems. Essentially

this phase of the modeling utilizes a computer program based on the so- tailed NASA Gordon and McBride code with the JANAF Thermochemical Tables

as a data base. This particular program has been used previously in our laboratory for related combustion problems and can handle complex multicomponent systems including both condensed and vapor phase species.

Essentially the computer program contains the basic thermodynamic data

for many but not all of the gaseous vapor and condensed phase components

pertinent to slag-ceramic-coal gas equilibria. For any specified set of

reactants and conditions of temperature and pressure one can calculate

the equilibrium composition. Typical output data for a representative

slag-coal gas system are shown in Table 1 . These data indicate a significant transport of alkali metal species and measurable amounts of iron

(as Fe(OH) 2

) and hydrogen cyanide to the vapor phase. We expect to

compare future calculations of this type with our experimental data,

such as those given in Figure 2 . New vapor species observed experimentally

will subsequently be included in the thermodynamic data base for the

equilibrium program. However, the basic thermodynamic data for such

species will first need to be determined either by auxiliary experiments,

e.g., by Knudsen effusion studies of appropriate equilibria, or by

estimation.

Plans : Pump failure due to the corrosive gases used in recent experiments

will require a major overhaul, including upgrading the rubber seals, of

the Roots blower used to back the main diffusion pump for the vacuum

system.

The new capillary probe which appears quite satisfactory for slag sampling

will be tested for its sampling fidelity by carrying out pressure independ< i studies using the Na2S04 calibrant system.

The slag vaporization studies will be extended to reactive atmospheres

containing, initially, H2O and H2 . The effects of known partial pressures

of H 2 0 and H 2 (in a N2 atmosphere) on the mass spectra, and particularly

the alkali metal and "unidentified" peaks, will be noted. By systematical'

varying the conditions of temperature and reactant partial pressure we should be able to identify the previously unidentifiable mass spectral

ions and determine their possible significance to vapor transport. Any

departure from thermodynamic equilibrium should also be apparent from

such data.

Complementary modeling calculations will be made for the experimental

systems using the JANAF data base.

36
Table 1 a Thermodynamic Prediction of Vapor Transport at 1300K and 23.8 atm

Major gases

b

Condensed Mineral Matter Inorganic Vapor Species

CH

4

1 .0 (-3)

° A1

2 0

3 1.8 (-3) NaOH 3 . 4 (-4)

CO 2 . 0 (-1) FeO 7.1(-3) Na 5 . 3 (-5)

COS 2 . 7 (-4) NaOH(l) 4 . 9 (-3) Fe (OH)

2 5 . 2 (-7)

C0

2 l.O(-l) Si02 1 . 8 (-3) HCN 3.7 (-7)

H

2 3 . 3 (-1)

H

2 0 3 . 2 (-1)

H

2 S 1 . 4 (-2)

NH

3 3 . 9 (-5)

N

2 4 . 4 (-3)

SiO 8 . 6 (-14)

(a) 1971 edition of JANAF Thermochemical Tables used as data base.

(b) Condensed components assumed to have unit thermodynamic activity.

-3

(c) 1.8(-3) denotes mole fraction 1.8 x 10
TEST

FOR

THERMODYNAMIC

EQUILIBRIUM

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(fl d C £

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38

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2

PRESSURE

(ATM)
MASS

SPECTRUM

FOR

ALKALI

SILICATE

VAPORIZATION

AT

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(i/m iv) 3ynss3yd "lvuavd

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39
4. Failure Prevention

a. Failure Information Center (R. C. Dobbyn, W. A. Willard and

J. H. Smith, 562)

Progress : During the quarter the Failure Prevention Information Center

received 37 reports of operational experiences and components and materials

failures in coal conversion pilot plants and process development units.

This number includes several diagnostic failure analyses from Argonne

National Laboratories and Oak Ridge National Laboratories. To date, the

percent contribution of information items received from different coal

conversion processes is shown in Table 1.

These reports have been classified and evaluated for technical completeness

and accuracy and discrepancies have been resolved. Detailed abstracts

of this information have been entered into the Center's computerized

data bank. A recent update of the frequency of failure modes, which

analyzes all information in the system, is shown in Table 2.

The Information Center continued to aid Battelle-Columbus in their

preparation of the DoE Materials and Components Newsletter feature on failure experiences. Weekly updates of all abstracts are furnished to

Battelle together with complete hard copy of certain reports when requested

During the quarter, the Center furnished 45 updated summaries and 18

complete reports.

The Information Center also handled 25 other requests for information

during the quarter. In response to these inquiries, copies of 645

abstracts and several draft reports were transmitted. In addition, six

visitors to the Center were briefed on its scope, operation and future

plans

.

During this quarter, major emphasis was placed on completing the analysis

of the performance of materials and components used in the Conoco C02

Acceptor Process Pilot Plant during its five and one-half years of

operation. Over 2400 operating events which resulted in process upsets

or run terminations have been investigated and analyzed. A detailed

report covering both metals and refractory materials is now in preparation

and will be forthcoming during the next quarter.

Direct contact with operating pilot plants, process development units

and failure analysis laboratories continued; the Synthane , Hygas and

Westinghouse and BCR-Bigas plants continued to interact with the Center.

One presentation was made and one paper was published by J. H. Smith,

describing failure experiences with Incoloy 800. Center staff also

participated in the annual Metals Properties Council Subcommittee 9

devoted to the properties of materials for coal conversion.

Plans : Plans for the next quarter include completion of the final

report covering the CO 2 Acceptor Process pilot plant and a similar, but

less detailed, report covering the operating experiences to date at the

IGT Hygas pilot plant.

40
In addition, liaison with the remaining gasification and liquefaction

pilot plants and PDU's* —those not yet visited—will be stepped up. Our

success with Synthane , Hygas , Bigas, etc., has demonstrated that this

technique works.

The format of failure data entries is being revised to facilitate information

exchange and further, in-depth analysis of common problems. These

analysis will become the subject of future reports issued periodically

and supplied to DoE for distribution. Submittal of candidate topics and

report outlines for DoE concurrence is also planned during the next

quarter.

*PDU = Process Demonstration Unit

41
Table 1

COAL CONVERSION PROCESSES

) OF ITEMS PERCENT PROCESS

7 1.28 ALL

17 3.12 BIGAS

1 0.18 BIOMASS

38 6.98 BMI

10 1.83 CARBONATE

21 3.86 CLEAN COKE

1 0.18 COED

73 13.41 C02

2 0.36 CPC

2 0.36 EXXON

3 0.55 GFERC

76 13.97 HYGAS

1 0.18 LERC

23 4.22 LIGNITE

20 3.67 MERC

34 6.25 MISC.

1 0.18 ORNL

3 0.55 PERC

1 0.18 RANN

2 0.36 SEVERAL

34 6.25 SRC

6 1.10 SRC-W

131 24.08 SYNTHANE

5 0.91 SYNTHOIL

1 0.18 UNKNOWN

31 5.69 WESTINGHOUSE

42
Table 2

NUMBER OF REPORTED INCIDENTS OF FAILURES

IN COAL CONVERSION PLANTS* **

FAILURE MODE ANALYSIS

PROCESS

FAILURE MODE CO 2 HYGAS SRC SYNTHANE OTHER TOTAL

CORROSION 48 37 11 29 67 192

AQUEOUS 0 2 0 0 3 5 CARBURIZATION 10 2 0 0 5 17

METAL DUSTING 4 0 0 0 3 7 OXIDATION 4 4 0 0 5 13

PITTING 3 7 3 7 9 29

SULFIDATION 16 12 0 8 5 41

GENERAL 11 10 8 14 37 80

STRESS-CORROSION 6 7 5 6 35 59

CHLORIDE 4 7 2 4 17 34

OTHER 2 0 3 2 18 25

MANUFACTURING DEFECT 14 10 13 25 47 109

DESIGN 6 4 13 15 33 71

FABRICATION 4 3 0 4 4 15

QUALITY CONTROL 4 3 0 6 10 23

EQUIPMENT MALFUNCTION 6 12 3 9 19 49

OVERHEAT 6 11 3 6 16 42

OVERSTRESS 0 1 0 3 3 7 EROSION 7 9 11 26 42 95

STRESS/TEMP FAILURE 1 6 1 7 16 31

CREEP 0 1 0 0 3 4

FATIGUE 0 2 0 4 10 16

THERMAL STRESS/SHOCK 1 3 1 3 3 11

UNKNOWN 4 11 0 27 17 59

* Incidents reported to NBS Failure Information Center - sponsored by

DOE,' Fossil Energy.

** Operating times and level of reporting vary with each plant.

INFORMATION SOURCE

R. C. Dobbyn

National Bureau of Standards

(301) 921-2952

43
4. Failure Prevention

b. Materials Properties Data Center (H. M. Ondik and T. A. Hahn, 565

and I. J. Feinberg, 562

Progress: During the past quarter the detailed cataloguing of the

contractors' reports has continued. The completed catalogue will make

it possible to identify all reports covering information on a given

property. The reports are being cross-checked with ORNL TIC and NTIS

computer files to determine the availability of these reports for more

general distribution. This information is also part of the catalogue.

The NTIS and ORNL TIC bibliographic files will also provide other possible sources of pertinent data. A thesaurus (i.e., properties, materials) must be constructed in order to form a sound basis for computer

filing and searching of the Materials Properties Data Base. The detailed

cataloguing described above provides the initial entries for the thesaurus. The thesaurus will also have to provide other sets of words to

permit flexible searching of the files, i.e., conditions of testing such

as temperatures, pressures, chemical environments, etc. and also sets of

keywords relating to the titles and general subjects of the projects.

The necessary equipment capabilities for the Data Center's computerterminal facility have been fully defined and identified. The facility

is to provide the following capabilities: text-editing of information

before entering it into the main computer storage, cathode-ray tube

display for checking before beginning printout operations, graphics

editing and handling from digitizing of initial input to appropriate

mechanisms for output. A properly designed equipment system can save a good deal in computer charges for central processing unit time, and in

personnel time. Equipment components have been chosen and are on order

for the establishment of the computer- terminal facility. The components

we have chosen to buy initially can interact with NBS Computer Division

graphics components, thereby providing us with some graphics capability

until we can expand our facility to include our own graphics digitizer,

plotter, and fast hard-copy printer. The equipment on order provides

two terminals with appropriate linkages for cross-communication, as well

as communication with the central computer. One terminal possesses a hard-copy printer, a dual-tape cartridge system, and sufficient selfcontained buffer storage to permit complete proof-reading and textediting of input material before entering data into the memory of the

central computer. The second terminal, an "intelligent" one, has a cathode-ray tube display, a single-tape cartridge arrangement, a 2

1 3 (%8000) byte (8 bit words per byte) core storage, and the appropriate

capability and accompanying software for handling graphical material.

Because of the core memory of the terminal, graphical information can be

edited and corrected before entering into the central computer storage,

as well as rearranged into graphical forms which may differ from the

44
original input in style, if that is desirable. Two modems, or couplers,

are also on order which provide the link via telephone lines with the

computer. The cost of the equipment components which are on order is

being covered by NBS funds.

In order to assure that the best choice of computer Data Base Management

System (DBMS) is made, the staff of the Center have arranged for and

taken a brief course dealing with the subject, and have obtained expert

advice. Investigation of DBMS availability has revealed two systems

which present the best possibilities for the use of this Center. Both

systems have several vendors and the details concerning each vendor

facility capability with regard to each system, and the detailed properties of each DBMS must be carefully evaluated so as to choose the most

advantageous combination, meaning usually the most flexible, economical,

and reliable.

Three summary reports, covering three projects and some 20 contractors'

reports are being prepared for DOE approval. They will cover, for a given project, work to date, or when possible, work done to a particular

point in the research, providing a suitable summary of a given achievement

or of a complete phase of the effort. The reports will be organized in

sections which will be headed generally as follows: project title,

investigators, objective (s) , methodology, materials studied, properties

investigated, experimental procedure, results (all to be presented as compactly as possible consistent with completeness) . Some variation

will, of course, occur due to the nature of a given project and the type

of material found on the contractor's reports.

The principal investigator attended the MPC Subcommittee 9 meeting held

in San Antonio during February; also, the meeting of consultants for the

Coal Conversion Systems Technical Data Book in Chicago in March.

Plans: The regular operations of the Center will continue—cataloguing

of report information, storage file design, preparation of data summaries,

checking of the ORNL TIC and NTIS data bases. Choice of the Data Base

Management System will be made. As the ordered equipment is delivered,

the terminal facility wll be put in use and data will be entered into

the system.