^(/l 77- /z<?£ C P-)

EA-6010-12

(Formerly FE-3800)

Dist. Category UC-90C

MATERIALS RESEARCH FOR CLEAN UTILIZATION OF COAL

QUARTERLY PROGRESS REPORT

April - June 1977

Samuel J. Schneider

Program Manager

Institute for Materials Research

National Bureau of Standards

Washington, D. C. 20234

PREPARED FOR THE UNITED STATES

ENERGY RESEARCH AND DEVELOPMENT ADMINISTRATION

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

(Formerly E(49-l)-3800)

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

States Government. Neither the United States nor the United States

ERDA, 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 2

Articles Published and Talks Presented 4

III. DETAILED DESCRIPTION OF TECHNICAL PROGRESS. ..... 5

1. Metal Corrosion 5

a. Constant Strain-Rate Test 5

b. Pre-Cracked Fracture Test 20

2. Ceramic Deformation, Fracture and Erosion .... 21

3. Chemical Degradation 23

a. Reactions and Transformations 23

b. Slag Characterization 30

c. Vaporization and Chemical Transport 50

4. Failure Avoidance Program 56

5. Appendix 60

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, a slow crack

growth and chemical degradation of refractories. A system has been

initiated to abstract and compile all significant operating incidents

from coal conversion 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 ERDA and associated contractors will be provided as requested.

II. SUMMARY OF PROGRESS TO DATE

Brief Summary

1. Metal Corrosion

a. Constant Strain-Rate Test

The set-up and calibration of gas mixing apparatus was completed for

testing in coal gasification environments except for supplying steam

since a failure occurred in the feed pump to the steam generator.

The original schedule for testing the alloys was modified to do the

normalizing environment (e.g., helium) first instead of the oxidizing

environment. The testing of all scheduled alloys at 10“6 s -1 at 450 °C

(840 °F) and 600 °C (1100 °F) in ultra-pure helium was completed. When

testing Inconel 671 at 600 °C (1100 °F) , a very significant decrease

in properties (tensile strength, elongation, and reduction in area)

occurred when compared to the results obtained when Inconel 671 was

tested at 450 °C (840 °F). This brittle type failure was similar to

what had previously been reported for 310SS. The brittle type

failure in Inconel 671 was attributed to the formation of the brittle

alpha chromium phase formed at 600 °C (1100 °F).

The above mentioned brittle failure of Inconel 671 and the previously

reported brittle failure of stainless steel type 310 indicate the

possibility of premature brittle failure of stressed components

manufactured of these alloys when used at elevated temperatures

apparently, regardless of the environment to which they are exposed.

1
b. Pre-Cracked Fracture Test

Elastic stress analyses were done to evaluate various modifications to

the wedge loaded DCB specimen to account for changes in elastic

modulus and thermal expansion. Additional modifications are being

considered to the specimen to reduce the effect of temperature on the

stress-intensity factor.

2. Ceramic Deformation, Fracture and Erosion

Work is continuing on construction and assembly of a high-temperature

,

high-pressure mechanical loader. A three zone furnace assembly has been

constructed around the inner environmental chamber, and is being characterized as a function of temperature and pressure. As part of the

mechanical testing of refractory concretes after exposure, a study has

been initiated in a 70% H2 0 - 30% C02 environment. Preliminary data

on a high-alumina concrete exposed at 610°C showed a slight increase

in strength at room temperature. The formation of calcium carbonate

was also observed.

3. Chemical Degradation

a. Reactions and Transformations

Construction of the pressure vessel for x-ray diffraction measurements has been completed. External heaters and safety shields have

been installed, and calibration runs with a saturated steam atmosphere

are in progress. Tests to date show that additional insulation will

be needed to permit operation at 1000°C without overheating the outer

wall of the pressure vessel. Meanwhile, five additional standard

patterns have been prepared. In situ diffraction measurements are expected to begin during August.

b. Slag Characterization

A pressure vessel for the determination of the viscosity of molten

slag compositions in steam has been designed, constructed and

preliminary heatings made at ambient pressure. The system has a design capability of 300 psig and 1450°C.

c. Vaporization and Chemical Transport

Calibration tests and vapor transport measurements on relatively

simple coal impurity systems (Nc 2 S 04 and NaCl) were made during the

third quarter. The technique and results were reported on by

Dr. bonnel at the Twenty Fifth Conference on Mass Spectrometry and

Allied Topics (Washington, D.C.). A copy of the extended abstract

for this paper is included as an appendix to this report. These

data indicated a very satisfactory performance by the reactor for

gas pressures up to 1 atm and temperatures of up to about 1400°C.

Species partial pressure measurements over a wide range of temperature

and pressure are planned for more complex systems involving compounds

comprised of Na, S, Cl, 0, and H.

2
4. Failure Prevention

The Failure Prevention Information Center continued to expand its

data collection activity. Fifty-eight additional reports of operating

experiences and failure analysis were received, classified, evaluated

and entered into the data base. Additional statistical programs were developed and modified for analyzing and outputing these data. Direct

contact with plant managers and engineers was initiated and a detailed

plan for conducting the first post inactivation analysis of an operating

pilot plant was written.

i#

3
Articles Published and Talks Presented

G. Ugiansky chaired the ASTM/NACE Symposium on "Constant Strain-Rate

Testing" and presented a paper, "Constant Strain-Rate Stress Corrosion

Testing of Metals in Gaseous Environments at Elevated Temperatures."

Dr. Bonnel presented a paper entitled, "Transpiration Mass Spectrometry

Studies of the Thermal Decomposition and Sublimation of Sodium Sulfate,"

at the Twenty Fifth Annual Conference on Mass Spectrometry and Allied

Topics (Washington, D.C., May 29-June 3, 1977).

J. M. Bukowski, E. R. Fuller, Jr., and C. R. Robbins, "Microstructural

and Mechanical Properties of Calcium Aluminate Refractories after

High Temperature Pressure Exposure," American Ceramic Society, 79th

Annual Meeting, April 27, 1977, Chicago, Illinois.

S. M. Wiederhorn and D. E. Roberts, "Erosion of Castable Refractories

for Coal Gasification Applications," American Ceramic Society, 79th

Annual Meeting, April 27, 1977, Chicago, Illinois.

4
III. DETAILED DESCRIPTION OF TECHNICAL PROGRESS

1. Metal Corrosion

a. Constant Strain-Rate Test (G. M. Ugiansky and C. E. Johnson, 312.04)

Progress : The set-up for testing alloys in coal gasification

environments was completed. A preliminary test run at 600°C (1100°F)

at a strain rate of 10"^ s - l with 310S and 347 SS specimens was used

to check out the system. A failure in the pump supplying distilled

water to the steam generator prevented the test from continuing in

the oxidizing coal gasification environment. The 310S and 347 SS

specimens were allowed to run in a dry atmosphere of 99% gas mixture

(23.8% CO, 31.8% C0 2 , 23.1% H2 , 21.3% CH4 ) and 1% H2 S. The results

of the preliminary test run at 600°C (1100°F) at a strain rate of 10“6

s --*- in that dry atmosphere show that the elongation and reduction in area for 310S and 347 stainless steel were virtually the same as for

310S and 347 SS tested at 540°C (1000°F) in H2 S which had been

saturated with water vapor at room temperature.

The original schedule for testing the various alloys in coal

gasification environments called for set up and calibration of gas

mixing apparatus (milestone la- 1 ), tests in an oxidizing environment

(milestone la-2), a normalizing environment (milestone la-3), and a reducing environment (milestone la-4). With the failure in the

pumping system and in the conservation of time, the schedule of tests

was changed and the tests in the normalizing environment were run

first. These tests have been completed for the various alloys at two

test temperatures, 450°C (840°F) and 600°C (1100°F), at a strain rate

of 1 X 10“6 s " 1 in ultra-pure helium. The data tabulated in table 1 are for the various alloys tested at 450°C (840°F) . Of these alloys

only 310 SS had previously been tested at or near this temperature.

It should also be noted that there is data for two new alloys not

previously tested, 446 SS (ferritic) and Inconel 671 (50 nickel 50

chromium)

Table 1

Alloy Tests at 450°C (840°F) at 1 X 10”^ s -

^ in Ultra-Pure Helium

Alloy Tensile Strength Elongation RA

MPa, psi % %

310 SS 602 87,300 37.9 64.6

310S SS 518 75,100 38.9 63.7

347 SS 568 82,300 18.8 65.2

446 SS 587 85,000 17.3 57.0

In 800 526 76,200 37.3 72.1

In 671 680 98,600 32.8 37.7

5
Table 2 shows the data for the various alloys tested at 600°C (1100°F)

.

Table 2

Alloy Tests at 600°C (1100°F) at 1 X 10-6

s _1

in Ultra-Pure Helium

Alloy Tensile Strength Elongation RA

MPa, psi % %

310 SS 415 60,100 (-31%)* 19.9 (-47%) 28.8 (-55%)

310S SS 437 63,400 (-16%) 31.9 (-18%) 42.8 (-33%)

347 SS 451 65,300 (-21%) 13.4 (-29%) 52.2 (-20%)

446 SS 152 22,000 (-74%) 62.0 (+358%) 86.2 (+151%)

In 800 467 67,700 (-11%) 37.1 (-0.5%) 60.1 (-17%)

In 671 425 61,600 (-37%) 13.3 (-59%) 15.6 (-59%)

In 671 (2nd Run) 4 16 60,300 (-39%) 16.1 (-51%) 16.3 (-57%)

*Note : The percent numbers in parentheses; in table 2 show the effect

of increase in test temperature from 450°C (840°F) to 600°C (1100°F)

whether the values of the properties decrease or increase when

compared to data in table 1.

It was previously known that the increase in temperature caused a significant decrease in property values for 310 SS due to a brittle

type fracture. The 310S was less affected by the temperature

increase than was 310 SS. The 347 SS also showed a decrease in

property values due to the temperature increase. Although Incoloy

800 showed a decrease in property values, it was the least affected

by the temperature increase. One of the new alloys tested, ferritic

446 SS, showed a large decrease in tensile strength when tested at

600°C (1100°F) as compared to the tensile strength when tested at

450°C (840°F). This large decrease was due to softening of the

metal; the 600°C (1100°F) temperature was above the temperature at

which 446 SS would be used. The large increase in elongation and

reduction in area was also due to the softening of the metal. Fig. 1 shows the fracture of 446 SS tested at 450°C (840°F); whereas. Fig. 2 is the fracture for 446 SS tested at 600°C (1100°F) . Figs. 3 and 4

show the cross-section at two magnifications of 446 SS tested at

450°C (840°F) . Note the 45° shear plane etched out in the photograph

of higher magnification. Figs. 5 and 6 show the cross-section at two

magnifications of 446 SS tested at 600°C (1100°F). Note the

elongated grains in the photograph at higher magnification.

The other new alloy, Inconel 671 (50 nickel-50 chromium), showed a large decrease in property values when tested at 600°C (1100°F) as compared to the property values obtained from a test at 450°C

6
(840°F). The two inconel specimens 671 tested at 600°C (1100°F) fractured

in a brittle manner with secondary cracks along the reduced sector much

the same as seen for 310 SS when tested at 540°C (1000°F) or 600°C

(1100°F) . No published data for elevated temperature properties of

elongation and reduction in area could be found for Inconel 671, but

the room temperature elongation and reduction in area are 25% and

30%, respectively. Short time tensile strength of Inconel 671 was reported as 690 MPa (100,000 psi) at 427°C (800°F) and 552 MPa

(80,000 psi) at 649°C (1200°F); whereas, our tests revealed tensile

strengths of 425 MPa (61,600 psi) and 416 MPa (60,300 psi) when

tested at 600°C (1100°F) at a slow strain rate of 10

-

^ s ~ .

Figs. 7 and 8 show the cross-section of the two Inconel 671 specimens

tested at 600°C (1100°F). Both figures indicate that the ductility

is low, that is, there is very little, if any, necking. In fact,

Fig. 7 shows that the specimen fractured in an area toward the

shoulder rather than at the minimum diameter. Figs. 9 and 10 are etched cross-sections of Inconel 671 specimens. These

photomicrographs indicate that another phase was formed when Inconel

671 specimens were tested at 600°C (1100°F) at a strain rate of 1 X

10"6 s -1

. This phase, according to International Nickel Co., is

alpha chromium, a brittle phase. The cracks and fissures in the

specimens seem to occur only in the brittle alpha chromium phase,

thus accounting for the reduction in property values as seen in table

2 when compared to table 1 . Fig. 11 is a photomicrograph of the

etched cross-section of the Inconel 671 specimen tested at 450°C

(840°F) . This photomicrograph indicates that some necking did occur

and that the fracture occurred on the 45° shear plane. Fig. 12 shows

that there is very little, if any, alpha chromium formed in Inconel

671 when tested at 450°C (840°F) at a strain rate of 1 X 10“6 s -

^,

thus accounting for the higher ductility as seen in table 1.

The above mentioned brittle failure of Inconel 671 and the previously

reported brittle failure of stainless steel type 310 indicate the

possibility of premature brittle failure of stressed components

manufactured of these alloys when used at elevated temperatures — apparently, regardless of the environment to which they are exposed.

Plans: Continue testing alloys in oxidizing coal gasification atmosphere.

7
Figure 1. Scanning electron micrograph of a 446 stainless steel

specimen tested at 450°C (840°F) at a strain rate of 1 x 1 0“ 6 s“ 1 in ultra-pure helium. 20X.

8
Figure 2. Scanning electron micrograph of a 446 stainless steel

specimen tested at 600°C (1100°F) at a strain rate of 1 x 1 0” 6 s” 1 in ultra-pure helium. 20X.

9
Figure 3. Photomicrograph of the etched cross-section of the 446

stainless steel specimen in Figure 1. 25X.

10
Figure 4. Photomicrograph of the etched cross-section near the

fracture of the 446 stainless steel specimen in Figure 1. 500X.

ll
Figure 5. Photomicrograph of the etched cross-section of the 446

stainless steel specimen in Figure 2. 25X.

12
Figure 6. Photomicrograph of the etched cross-section near the

fracture of the 446 stainless steel specimen in Figure 2. 500X.

13
Figure 7. Photomicrograph of the etched cross-section of the

fractured Inconel 671 specimen tested at 600°C (11 00° F ) at

1 x 10" 6 s" 1 in ultra-pure helium. 25X.

14
Figure 8. Photomicrograph of the etched cross-section of the fractured

Inconel 671 specimen tested at 600°C (1100°F) at 1 X 10"^ s"^

in ultra-pure helium. 25 X

15
Figure 9. Photomicrograph of the etched cross-section of the

Inconel 671 specimen in Figure 7. 500X.

16
Figure 10. Photomicrograph of the etched cross-section of the

Inconel 671 specimen in Figure 8. 500X.

17
Figure 11. Photomicrograph of the etched cross-section near the

fracture of an Inconel 671 specimen tested at 450°C (840°F) at

1 x 1 0“ 6 s” 1 in ultra-pure helium. 25X.

18
Figure 12. Photomicrograph of the etched cross-section of the

Inconel 671 specimen in Figure 11. 500X.

19
b. Pre-Cracked Fracture Tests (J. H. Smith, 312.01)

Progress : Further work was done to optimize the design of the wedge-loaded

cantilever-beam test specimen for use at elevated temperatures. For test

materials of interest, the decrease in the elastic-modulus at elevated

temperatures causes a substantial decrease in the elastic stress-intensity

factor. This decrease in modulus cannot be fully compensated for by

increases in thermal expansion or decrease in yield strength of the test

specimen so that the stress- intensity will remain relatively constant as temperatures increase. Of equal significance is the fact that the stressintensity in a wedge-loaded double cantilver beam specimen will increase

as the specimen is cooled from elevated temperatures back to room temperature

after testing. Several other test specimen configurations have been

investigated to determine if the stress-intensity can be made less sensitive

to changes in temperatures of the specimen.

Additional elastic stress analysis was done to evaluate various modifications

to the wedge loaded DCB specimen. For selected materials of interest in coal

conversion systems, such as 310 stainless steel, the decrease in stress

intensity due to increase in temperature can be limited to approximately

10 percent up to a temperature of 1000°F and to about 20 percent up to 1200°F.

Plans : The wedge-loaded cantilever beam specimen will be optimized so that

the stress- intensity is accurately defined for several materials of interest

at a series of selected temperatures. Several additional specimens will be

analysed to determine if they are more suitable for use at elevated

temperatures.

The elastic-plastic stress analysis of the wedge-loaded double cantilever

beam specimen to determine the stress-intensity and J-integral values will

be initiated. This will be done using stress-strain curves for specific

test materials of interest at selected temperatures.

Continued analysis of the DCB and modified DCB specimen configurations will

be carried out to optimize the specimen design and to develop a specimen

that exhibits a constant stress-intensity, K, over a reasonably wide range

of temperatures for materials of interest. Several specimen configurations,

other than the DCB specimen, are being evaluated to extend the useful

temperature range of the specimen. Elastic-plastic stress analyses of the

specimens will be initiated to extend the use of the specimen beyond the

range of applicability of the elastic analyses.

20
2. Ceramic Deformation, Fracture and Erosion (E.R. Fuller, Jr.,

S.M. Wiederhorn, J.M.

Bukowski, D.E. Roberts,

and C.R. Robbins, 313.05)

Progress : The major effort of this past quarter has been directed to

the continued construction of a high- temperature , high-pressure mechanical

loader. Construction of a three-zone furnace assembly around the inner

environmental chamber has been completed along with the wiring of the

temperature controllers necessary for operation. A total of twelve

thermocouples have been placed in the unit so that the temperature

profile can be determined under actual operating conditions. Five of

these thermocouples are located in the inner environmental chamber. The

remaining thermocouples monitor the temperature profile throughout the

outer containment pressure vessel. Stainless steel baffles are used to

restrict convection currents and to lower the radiant heat transfer in

the inner chamber.

Several runs at atmospheric pressure have been made in a nitrogen

environment (low partial pressure of oxygen) to a temperature of 1000°C.

The temperature gradient inside the sample chamber could be controlled

to 5°C or less. Heat losses to the outer vessel under these conditions

were found to be minimial even at the maximum operating temperature of

1000°C. A failure of a temperature controlling thermocouple resulted in

the disassembly of the outer pressure vessel for replacement. The exact cause of failure has not been diagnosed, but because of the low partial

pressure of in the environment, "green-rot" of the chromel-alumel

(type K) thermocouples is suggested. Presently, sheathed thermocouples

are being prepared for use in the unit, and will be installed once the

checkout phase is completed.

As part of the mechanical testing after hydrothermal exposure, two

lengthy exposure tests were conducted this quarter. In one, high

alumina refractory concrete specimens were heated to a temperature

of 910°C (1670°F), after which the steam pressure was increased to 7 MPa

(^ 1000 psi) . The time of exposure at temperature was 330.5 hours.

These high alumina specimens showed an increase in flexural strength

from 19.0 + 1.2 MPa (2,750 + 180 psi) to 29.2 + 6.7 MPa (4,240 + 970

psi). In the other exposure test, high alumina specimens were heated to

41Q°C following the saturated vapor curve to a pressure of 7.0 MPa.

After a 46 hour exposure at 410°C, the temperature was increased (at

constant pressure) to 610°C for a 43 hour exposure. Following this

exposure, the temperature was increased to 910°C for a 335 hour exposure.

These specimens showed a similar strength increase to 31.0 + 7.5 MPa

(4,490 + 1,090 psi). Mineral phases were predominantly a-alumina, and

CaO.lAl^O^, but some hydrated phases apparently formed during cooling

from temperature. It is the formation of these hydrated phases that are most likely responsible for the increase in strength shown by the concrete

specimens after hydrothermal exposure.

21
Exposure studies on high alumina concrete in a 70% ^0-30% CC>2 environment have also been initiated this quarter. In this set of experiments,

the pressure vessels are charged with calculated amounts of both CO

2 and

H

2 O at room temperature so that the pressure at the exposure temperature

is approximately 7 MPa ('ilOOO psi) . Cursory data on high alumina concrete

exposed at 610°C for 42 hours showed only a slight increase in room- temperature flexural strength from 15.6 +0.7 MPa (2,2262 + 102 psi) to

20.5 + 1.5 MPa (2,973 + 218 psi). X-ray analysis also showed the formation

of calcium carbonate in the refractory concrete specimens.

Plans : Construction of the high pressure vessel for mechanical testing

in simulated gasification environments will be continued. Once the heat

zone has been fully characterized as a function of temperature and

pressure, the pressure balancing unit will be installed. On satisfactory

operation of both the heating and pressure system, the load system will

be installed and the operation of the hydraulic ram, bellows and load

cell will be checked using refractory concrete specimens at ambient,

high, and low temperatures, and at pressure. Finally the water injector

will be installed and the system will be operated with steam in the

environmental chamber. When this check-out scheme is completed, the

system will be operational and systematic studies on refractory concretes

will commence.

Exposure studies will continue on both the high-purity alumina and the

calcined flint clay castable refractories for gas mixtures of 70% HO - 30% CO

2 and 30% H O - 70% CC^. Following the completion of these studies,

a gas mixture of approximately 15% CC^, 20% CO, 25% H^, and 40% ^0 by

volume will be used. With the exception of H S and NH^, the latter

mixture will fully simulate the coal gasification environment. As in

the previous studies, a range of temperature, pressure and exposure time

will be investigated. The erosion resistance at room temperature of

exposed refractory concrete specimens will also be characterized. X-ray

diffraction and scanning electron microscopy will be used to identify

important phase changes that occur during exposure.

22
3. Chemical Degradation of Ceramics

a. Reactions and Transformations (F. A. Mauer and C. R. Robbins, 313.06)

Progress : During the past quarter assembly of the pressure vessel for

x-ray diffraction measurements was completed. External heaters were

installed and a safety shield was constructed to limit damage in case of

failure of the pressure vessel.

The B^C x-ray windows were judged to be too rough for satisfactory

sealing with metal gaskets even after they had been ground to the desired

dimensions. They were sent to the optical shop for polishing, and,

since the surface still appeared somewhat grainy, they were plated with

gold to provide an improved seat for the gaskets. The gasket seats in

the stainless steel pressure vessel were lapped with diamond paste to

remove tool marks before final assembly of the x-ray ports containing

the B4 C windows

.

The initial pressure test was carried out with N2 gas to a maximum

pressure of 1400 psig. The pressure dropped to 700 psig during the

following 20 hours, indicating that some leakage occurred possibly as a result of porosity of the hot-pressed B^C windows. This amount of

leakage can easily be tolerated.

Calibration runs with a saturated steam atmosphere have been carried out

to determine the power input required to maintain various temperatures.

These have proved to be quite time consuming because of the time required

to establish equilibrium. The three external heaters provide a maximum

of 650 watts distributed over the top, bottom, and sides of the pressure

vessel. Approximately one inch of fiber insulation surrounds the heaters.

A power input of 220 watts is sufficient to maintain a wall temperature

of 300°C when the internal heater is off, but because of the mass of the

pressure vessel ( 8.6 kg), the additional power is needed to reach operating

temperature within one hour. When power is applied to the internal

heater the input to the external heater must be reduced by a like amount

to avoid an increase in wall temperature. For inputs in excess of 200

watts, it is no longer possible to limit the wall temperature to 300°C with

the present arrangement. When the wall temperature was allowed to reach

379°C, a loss of pressure occurred, presumably because of failure of the

Teflon thread sealant (Tmax^250°C) at the base of the water reservoir.

This seal can be relocated to a region of lower temperature or eliminated

altogether.

With the present internal heater which is wound with 0.032 in. diameter

80% Pt - 20% Rh wire we are limited to 450 watts input, which is sufficient

to reach a sample temperature of 900°C. To reach the specified temperature

of 1000°C while maintaining a wall temperature of 300°C it will be

necessary to provide additional insulation around the furnace core to

reduce heat transfer by convection. We plan to cast the furnace core in

a block of alumina with a bubbled-alumina aggregate, which can be done

with no change in the design of the pressure vessel itself.

23

1
Additional standard patterns of relevant cement phases have been recorded

by the energy dispersive powder diffraction method. The patterns are shown in Figures 1-5. The conditions are the same as for the eight

patterns included in our previous quarterly report (January-March 1977).

The identification of peaks is not shown in Figure 5 (CAS 2 ) because of the

complexity of the pattern, although the indexing has been carried out.

Plans: Modifications to the internal heater to reduce heat transfer to

the outer wall of the pressure vessel will require approximately one month to complete. Only a moderate reduction is required and x-ray

diffraction measurements are expected to begin during August 1977.

24
Figure 1. EDXD pattern of C^A.

(C = CaO, A = A1 2 0 3 )

25
26
Figure 3. EDXD pattern of C AH . J D

(C = CaO, A = AI 2 O 3 , H = H2 0)

27
10K

8K

6K

O

C->

4K

2K

Figure 4,

400 600

CHANNEL NUMBER

EDXD pattern of

28
Figure 5.. EDXD pattern of CAS

2

.

29
. b. Slag Characterization (W.S. Brower, J.L. Waring, 313.03 and

D.H. Blackburn, 313.02)

Progress :

1 . Design of High Pressure/Temperature Vessel

A high pressure vessel potentially capable of achieving temperature

of 1350°C and 100 psi of steam has been designed and constructed at NBS

.

This apparatus is to be employed in the measurement of viscosity of

molten slag at high steam pressures. The apparatus (Figures 1, 2) was fabricated from 304L ss and is approximately 24" long and 10" in

diameter with a total volume of approximately 2072 in^. The main

body of the vessel was fabricated from Schedule 40S pipe. The top

and bottom (Figure 3) 10 inch flanges are class 300 and are fastened

with sixteen one inch bolts. The two side ports with cover plates

are also class 300 which are held in place with eight 3/4" bolts.

The side ports (Figure 4) serve to introduce two massive copper

electrodes (Figures 5, 6) necessary to carry sufficient current to

heat a platinum heater in steam, while maintaining the pressure

integrity of the vessel. These electrodes are isolated from the

vessel body by mica. The copper electrode seal is made with the

flange using an "0" ring in conjunction with a split lock collar

(Figure 7) and retaining ring (Figure 8)

.

2 . Steam Generation

The steam used in the apparatus is generated internally by

vaporizing water using nine bayonet type heaters (Figure 9) which

together dissipate approximately 3600 watts. These heaters are isolated from the internal pressure by three finned copper heat

exchangers (Figures 10, 11, 12). There are three heaters in each

copper radiator. The internal and external surfaces of the radiators

are pressure isolated by an "0" ring seal. At this point it should be

mentioned that all "0" ring seals employed in this apparatus are fabricated from ethylene propylene. This material appears to offer

the best resistance to high pressure steam. Figure 11 shows the

relationship between the heaters and the heat exchangers . The bayonet

heaters are supplied power from a 10 KVA S.C.R. power supply used in

conjunction with a current adjusting type controller. These bayonet

heaters must be controlled since they in effect control the steam

pressure in the vessel. A baffle assembly (Figures 13, 14) is used

above the copper heat exchangers to reduce bumping caused by the

evolution of steam. A copper-copper constantan thermocouple is used

with this devise to monitor steam temperature, hence pressure. To

reduce radiative and convective cooling of the platinum heater, a

30
refractory castable Is placed around the heating element. To minimize

refluxing H2 O, three shields are placed above the specimen.

3 . Temperature Measurement and Control

The high temperature to which the samples are to be heated is

achieved by passing high current through a platinum cylinder fabricated

from platinum sheet 1 mm thick. The cylinder is six inches in length

and 2 1/2 inches in diameter. This cylinder has two tabs or ears welded on the long axis 180° apart. The total radiating surface of

the heater is approximately 29 in. These tabs are compressed between

two copper plates which comprise the ends of the copper electrodes.

These copper plates have been gold-plated to minimize contact resistance

in the presence of steam.

The platinum cylinder is heated with a controlled 10 KVA power

supply used in conjunction with a 100-1 step-down transformer. The

temperature of the heating element is measured with a Pt-Pt-10%RH

thermocouple. This system is estimated to control the temperature

of the melt to ±10°C.

4 . High Temperature/Pressure Viscometer

The crucible containing the molten slag is made of 0.025 inch thick

platinum and is 1 1/2 in diameter and 3 in. high. The crucible is

mounted and centered on an alumina pedestal which extends into a shaft coupler attached to the drive mechanism (Figure 15). The viscosity

bob is 12.5 mm in diameter, 50 mm in length with 45° tapered ends and is

suspended by a platinum rod.

The spindle is suspended in the vessel with a phosphor-bronze

wire which serves as a torsion member. At the lower end of the torsion

member a permanent magnet is attached and moves as the torsion member

is twisted. This magnet movement is detected by a ferrous metal

detector located outside of the vessel. The driving mechanism (Figure

15) which turns the shaft and crucible consists of a 1/4 H.P. electric

motor which drives a right angle gear reduction mechanism. The reduction

ratio is 48-1. The shaft speed is variable from 2 to 44 rpm. The

shaft enters the pressure vessel through a ethylene propylene "0"

ring seal. The rate of rotation of the shaft assembly is monitored

with an electronic tachometer.

5 . Experimental Methods

The appratus described previously is calibrated at room temperature

with a standard of known viscosity by measuring the angular deflection

of the bob and noting the speed at which the crucible was rotating. A

31
viscosity standard must be selected which approximates the viscosity

of the molten test slag. The liquids used for calibration were Dow

Corning silicone fluids which have viscosities of 58,560 centipoises

and 12,500 centipoises, respectively. The deflection 0 of an inner

bob in a rotating fluid is directly porportional to the viscosity n of the fluid and the angular velocity U) of the outer rotating crucible

0 = cwn

where C = constant of porportionality depending on the geometry of the

apparatus. The angular deflection 0 of an unknown liquid can be com- pared with that of a standard of known viscosity by:

_1 _ "22 _ 21

e 2 or n2 ni 0^2

where t*ie unknown viscosity.

Having the apparatus calibrated, the specimen is placed in the

vessel. In a conventional viscosity apparatus, uncomplicated by the

presence of a pressure vessel the specimen is melted and elevated to

a sufficient height to immerse the bob. However, in this apparatus

because of the restrictions imposed by pressure the slag will be

melted (bob in place) in another furnace in air and this unit will

be placed in the proper position in the pressure vessel. At this point

the steam will be generated. Then the power will be turned on to

remelt the slag. Several measurements will be taken with the shaft

rotating in the clockwise direction and several in the counter clockwise direction.

In the last quarterly report the viscosity of a naturally occurring

slag derived from Montana Rosebud Ash was compared with several selected

synthetic compositions. In the synthetic compositions the silica was

allowed to vary from 30 to 50 weight percent. In the presence of steam

it is felt that the most significant changes in viscosity will be due

0

I to changes in the O-Si-O bonding in the melt due to incorporation of

0

(OH) ions. As SiO_ is the component which most affects viscosity at

ambient atmosphere this variation should show the greatest affect under

steam pressures. When the composition of the atmosphere is varied,

changing the partial pressure of oxygen, variations of iron oxide

content might well prove to have a significant effect on the viscosity.

32
At atmospheric pressure typical coal slag viscosities have been

found to remain essentially constant as the oxygen activity is

decreased. However, increasing the oxygen activity over that of

air tends to* increase the viscosity with increased Fe+^ content

of the melt. Reducing atmospheres that are typical in coal

gasifier environments are not expected to have a really significant

effect on viscosity, however large variations in iron content of

the slag may well influence the viscosity as the total amount of

Fe+^ will be increased and might be expected to decrease the

viscosity much the same as increased Ca+^ content.

*W. Capps, private communication.

Plans : Construction and assembly of the major components of the

pressure vessel, viscosity apparatus, have been completed. Preliminary heating and steam generation will begin by the end of

July. Operation will begin with one atmosphere steam pressure

moving to progressively higher pressures.

33
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

H - bob

I - 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

R - shaft drive mechanism

34
Figure 2. Three quarter view of high pressure-temperature viscometer.

35
Figure 3. Drawing of lay-out of large bottom flange.

36
I

Figure 4. Photo of electrode flange.

37
Figure 5a. Copper electrode.

38
*Jcx <jced Wea-iK** National Bureau of Standards

Figure 5b. Copper electrode and flange assembly
partial section a-a

Figure 6. Drawing of copper electrode supplying current to platinum electrode
Figure 7

Drawing of split lock collar for clamping copper electrode into flange.

41
Figure 8. Drawing of retaining ring used for clamping copper

electrode into flange.

42
Figure 9. Bayonet heaters used for steam generator.

43
Figure 10. Heat exchangers used to isolate bayonet heaters from pressure

and to transmit heat for steam generator.

44
Figure 11. Heat exchangers and bayonet heaters.

45
Figure 12. Drawing of heat exchangers.

46
Figure 13. Heat exchangers and convection baffles.

47
y/j B HOLES EQLSP

OfiJi B.C.

±32

Figure 14. Drawing of convection baffles.

48

k^vvr

"iia^av^v

i

1 i
Figure 15. Viscometer drive mechanism showing bob and

suspension similar to that employed in high

temperature pressure vessel.

49
c. Vaporization and Chemical Transport (J. Hastie and D. Bonnell, 313.01)

Progress ; Using the redesigned reactor constructed during the second

quarter (FY 77), we have carried out an extensive series of calibration

tests using N^SO^ and NaCl as test materials. A schematic of this

latest reactor design is shown in Figure 1 and an external photographic

view of the reactor components is provided by Figure 2. Note in Figure 1

the close proximity of the sample boat, thermocouple and sampling orifice,

thus ensuring an essentially isothermal condition between these three key

elements of the reactor. During operation, the reactor is coupled to a molecular beam High Pressure Sampling Mass Spectrometer system which has

been described in detail elsewhere*.

The vaporization results of our calibration tests have been analysed, using

conventional second and third-law thermodynamic treatments, to indicate

that the composition of the molecular beam generated by the reactor sampling

probe is a good representation of the gas-vapor composition in equilibrium

with the condensed phase (Na2S0^ or NaCl in this case). Typical data

obtained with this reactor are shown in the plots of Figures 3 and 4.

Here the vapor composition data are summarized in the form of reaction

equilibrium constants Kp for the reactions

Na2S0^ (solid or liquid) = 2Na + SO

2 + 0

^ and

NaCl (solid or liquid) = NaCl

We should stress that these test salts are highly reactive materials in

their liquid and vapor forms and the demonstrated good reactor performance

in these cases leads to an optimistic outlook for the reactor capability

under the planned simulated coal-gasifier conditions. Data such as those

represented in Figures 3 and 4 are unique, as heretofore there has not

existed a technique capable of monitoring the molecular weights and

partial pressures of high temperature species in complex vapors at total

pressures in the vicinity of 1 atm.

While we are confident that much useful data on coal gasifier reactions can

be obtained with our present apparatus, we believe it important to pursue,

eventually, the more difficult problem of making analogous measurements

at much high pressures, i.e. 3 20 atm or more. Such a prospect was envisioned in our original project proposal, and can now be initiated

using supplementary funds from our related projects in flame chemistry.

Accordingly, during this past quarter we have designed a new so-called

Ultra High Pressure Sampling Mass Spectrometer system, details of which

can be provided in a later report. The key improved performance factors

designed into the new system are as follows:

• ability to sample from larger capacity reactors (£.0. _, ^ m^ vs ^ cnP

gas volume)

50
2

• sampling from vertical, as opposed to the present horizontal, reactor

orientations

• sampling of high temperature 1400 C) gases and vapors at pressures

of at least 20 atm, as compared with the present 1 atm limitation

• use of larger sampling orifices, e.g., 20 mil as compared with the

present use of 3 mil orifices—thus reducing any tendency for orifice

plugging by small particles.

Each of these new performance factors should allow for a much closer

approach to actual coal-gasifier conditions. This capability will be

particularly important for those reactor conditions where large departures

from thermodynamic equilibrium exists; though at present we do not have

any specific information about what these conditions are likely to be.

It should be noted that our present transpiration reactor is capable of

operating at much higher pressures ( i.e. 3 ^ 10 atm) than the mass spectrometer system is capable of handling. Use of faster vacuum pumps

and additional differentially pumped vacuum chambers, as has been designed

into the new system, would allow for better utilization of the present

reactor

Plans ; We expect to proceed with our original plan of systematically

increasing the chemical complexity of the gas-solid (or liquid) reactions

to be monitored with our present reactor—mass spectrometer system.

Specifically, during the next quarter we will monitor the vapor transport

processes for Na2S0^ and NaCl in the presence of high partial pressures

of SC> 2 , C>2 and 1^0

• Hastie, J. W. Combustion and Flame, 21_, 187 (1973).

51
® « I

<f> o

cn

k- or ** 5 u O o. h- C/5

S-i 04 cd o i—1 4-1 d a o 1 a) CO

O! i—i cd PC o 00 B d ® o cd -d

•H 4-1 4-1 OO

cd

a <4-4 04 •H O

•H 4-1 co Cd

®

co 5-i > • d <D •H d

cd

d 4-1 o

o» 0) cd •H H 00 4-1 4-1 d •H

<4-4 04

® CO

OO co

O

M-4

® Co

O y>

B

•H CO o

4-1 r—1 ®

a

cd rQ 04 6 B S-4

CL) a)

B o

,d CO cd Co a CO a) cd cn <J -O > ®d

oo •H

Pd

52
Figure

2.

Photo

of

main

Transpiration

Reactor

components,

showing

the

thermocouple,

sample

boat

and

Pt

reactor

with

nozzle

and

skimmer

attached.
1800

TEMPERATURE (Kelvin)

1600 1400

03 CU <U P-i CO cu CO 1—1 d >

a> cd o

pm

aH CO cd a- o •U cd 44 X P-4 cd cd 0) a. p-l cd 03 •H -H 44 a (to- cd i—! <u a) co 03 cd pm pm d 44 d cd CU d

44 • P-l P4 cu

cd CO

H

d 0

Pm > 44 •H

a) a) cd p4 a, HI 43 p-i CU 0 p-l u cu (to- cu d 44 pe •u CO 43 i-l CU

CO 4-4 i—1 a> •rt cu

u P-4 £ CU 43 •H ci- 43 44 03 44 1 •1 cd CU 1 Pm

a) Z d CO CO

O

PM •H •r-4 cu 44 d toO cd I—1 O

CO o 44 CU 4to cd CO rH 4to > cd CU

CU

O P-lH Pm Pm 4-4 d

oO CU o i—I CU

P-4 cd 43

d s CU 03 o 44 o p-l 5 •H *H o S CU

4-> 4-1 CO

O CU 44

•r-( 44 CO 43 cd CO a d CJ Pm O •H •r-t <U O 43

PB o 43 0 •H 6 cd d- E-t P-l t—! o d CU cd u kO cd 43 O

CU 03 44 • H

03

O cd

B

O

B 03 (U Pm 44

5-4 44

C c>* <3 03 CO jz t—1 '—

jd OJ >0

u

J- 4-1 i—1 CO •“3 cd o a

C/to & PJ Pj CU <N cd •H 0) 43 be

cd t—i O 44 44

d Z CU •H

03 e CO 4M d - o 43 d O o cu p-l a p-i 44 03 03 d <U d O CU cu o CO 44 CU N N

*rH cd OH •H

44 CU P-4 co >4 rH

cd 43 CU cd cd rl +J (to. CO 0

P-4

B CO § Pm

cd

d cu cd

d

O > •H 44 55 CO d

co

a)PMd

00 •H

Pm

54
LOG

PRESSURE

NaCI

[atm]

TEMPERATURE (Kelvin)

1200 1100 1000

55

Figure

4.

Varation

of

apparent

NaCI

vapor

pressure

with

temperature

using

the

argon

mass

spectrometric

ion

intensities

to

convert

NaCl+

intensities

to

partial

pressures.

The

observed

displacement

of

the

experimental

and

literature

(i.e.,

JANAF)

curves

is

attributed

to

the

different

free

jet

expansion

properties

of

argon

and

NaCI

and

to

their

different

ionization

cross
4. Failure Prevention (J. H. Smith, W. A. Willard and R. C. Dobbyn, 312.01)

Progress : During the quarter the Failure Prevention Information Center

received fifty-eight reports of operational malfunctions and components and

materials failures in coal conversion pilot plants and process development

units. This number includes several diagnostic failure analyses from

Oak Ridge National Laboratories and Argonne National Laboratories. To

date, the percent contribution of information items coming from different

coal conversion processes is shown in Table 1.

These reports have been classified and evaluated for technical completeness

and accuracy and certain discrepancies have been resolved. Detailed abstracts

of this information have been entered into the computerized data base

management system. A recent update of the frequency of failure modes,

which analyses all information in the system, is shown in Table 2.

The Information Center continued its close collaboration with Battelle - Columbus in the preparation of the ERDA Materials and Components Newsletter

feature on failure experiences. Weekly updates of all abstracts are furnished to Battelle together with complete copies of all significant

information.

During this quarter the Information Center handled forty-one separate

requests for information. In response to these inquiries, copies of

827 abstracts, 67 complete reports and over 20 copies of the draft abstract

reports were sent out. In addition, 10 visitors to the Center were briefed

on its scope, operation and future plans.

Three additional abstract reports were prepared; each addresses a specific

failure mode: erosion, corrosion and stress-corrosion cracking. This brings

the total number of abstract reports to nine. The abstract report has been

chosen as the initial format for the timely and efficient dissemination of

information from the Center. Two of these reports, Corrosion and Incoloy 800, are in the final stages of NBS editorial review and should be available

shortly.

i Direct contact with pilot plant and failure analysis laboratory personnel

was initiated during the quarter with visits to Synthane, MERC, BIGAS and

the Westinghouse PDU completed. This activity has established firm channels

of communication between the plants and the Center and has also provided

additional failure and plant operation data.

Project staff also developed a detailed plan for a materials and components

performance analysis of the CO2 Acceptor Pilot Plant, including the establishment of a task force of ERDA, NBS and plant personnel. The study is to be

conducted by ERDA later this year.

Plans : The information gathering phase of this project will continue as more information is received and additional contacts are made with pilot

plants, process development units, failure analysis laboratories and other

coal conversion technology centers. Additional abstract reports, now in

various stages of completion, will be issued and new, more extensive, in-depth

failure information dissemination schemes will be explored.
In addition to this expanded Information Center activity considerable effort

is expected to be devoted to the review and evaluation of the performance of

materials and components used in the CO2 Acceptor Process pilot plant over

the next eight months.

57
Table 1

COAL CONVERSION PROCESSES

NO. OF ITEMS PERCENT PROCESS

7 1.71 ALL

1 0.24 BIGAS

1 0.24 BIOMASS

16 3.92 BMI

10 2.45 CARBONATE

17 4.16 CLEAN COKE

1 0.24 COED

70 17.15 C02

2 0.49 CPC

2 0.49 EXXON

1 0.24 GFERC

64 15.68 HYGAS

1 0.24 LERC

24 5.88 LIGNITE

15 3.67 MERC

29 7.10 MISC.

3 0.73 PERC

1 0.24 RANN

2 0.49 SEVERAL

31 7.59 SRC

2 0.49 SRC-W

89 21.81 SYNTHANE

4 0.98 SYNTHOIL

1 0.24 UNKNOWN

14 3.43 WESTINGHOUSE

408 = Total Number of Items in File.

58
Table 2

NUMBER OF REPORTED INCIDENTS OF FAILURES

IN COAL CONVERSION PLANTS

FAILURE MODE ANALYSIS

FAILURE MODE C02 HYGAS SRC SYNTHANE OTHER TOTAL

CORROSION 48 32 11 24 58 173

AQUEOUS 0 2 0 0 3 5

CARBURIZATION 10 2 0 0 5 17

METAL DUSTING 4 0 0 0 2 6

OXIDATION 4 3 0 0 5 12

PITTING 3 5 3 5 9 25

SULFIDATION 16 11 0 7 3 37

GENERAL 11 9 8 12 31 71

STRESS-CORROSION 6 4 5 4 24 43

CHLORIDE 4 4 2 4 17 31

OTHER 2 0 3 0 7 12

MANUFACTURING DEFECT 14 9 13 18 34 88

DESIGN 6 3 13 8 25 55

FABRICATION 4 3 0 4 3 14

QUALITY CONTROL 4 3 0 6 6 19

EQUIPMENT MALFUNCTION 6 10 3 5 10 34

OVERHEAT 6 10 3 2 10 31

OVERSTRESS 0 0 0 3 0 3

EROSION 6 6 11 20 28 71

STRESS/TEMP FAILURE 1 6 1 6 14 28

CREEP 0 1 0 0 3 4

FATIQUE 0 2 0 3 9 14

THERMAL STRESS /SHOCK 1 3 1 3 2 10

UNKNOWN 2 11 0 19 7 39

NOTES

* Incidents Reported to NBS Failure Prevention Information Center

- Sponsored by ERDA, Fossil Energy

** Operating Times and Level of Reporting Vary with Each Plant

59
Appendix

5. Supportive Chemical Thermodynamics Calculations (W. S. Horton, 313.01)

Chemical thermodynamics calculations and computer programming were begun this quarter in support of the materials testing under simulated

gasifier conditions. A need was recognized for having the capability

to perform calculations involving simultaneous chemical equilibria.

Consequently this short term activity was initiated.

It is very likely that the gaseous environment prepared for a test

will change composition; that it will change toward an equilibrium

composition if that is not the initial state. Although the extent

of the change will be limited by unknown chemical reaction rates,

it is important to know the maximum amount of change that can occur.

To provide this information requires calculations of simultaneous

chemical equilibria. This problem has been studied by many, and

specialized computer programs are available. However, it is necessary

to develop an interactive program that is useable with a timesharing

service. With such a program properly developed, the personnel performing tests may, with a few simple operations at a terminal, obtain answers

for any mixture of test gases they propose to use. This will be very

useful to such personnel particularly if they are not familiar with

details of chemical equilibria calculations and the complex batch computer

programs available for them.

The mathematics were reviewed, and the development was begun of an algorithm based upon minimization of the Gibbs energy of the system.

Several tests of prototype programs have been made successfully.

These show that the algorithm works successfully when tailored to a system of conditions and starting composition for which the existence

of condensed water and/or carbon is known a priori.

Plans : Efforts will be directed toward combining the simple cases with respect to condensed species into a single general algorithm.

This problem together with that of convergence (or its equivalent:

initial estimates of equilibrium composition) are typically the

difficulties associated with writing computer programs for simultaneous

chemical equilibria.

60
TRANSPIRATION MASS SPECTROMETRY STUDIES OF THE THERMAL DECOMPOSITION AND

SUBLIMATION OF SODIUM SULFATE

J. W. HASTIE , D. W. BONNELL AND D. M* SANDERS

Institute for Materials Research

National Bureau of Standards

Washington, D. C. 20234

Past experience in our laboratories using modulated beam mass spectrometry in Knudsen effusion and direct atmospheric sampling of flames has

prompted an adaption of these techniques to the problems of sampling

systems of interest under "real world conditions". Areas of interest here

include sampling and characterization of model coal gasification environments and characterization of species involved in the vaporization of

glasses

Figure 1 shows a schematic of the high pressure sampler and an external photographic view of the components is provided by Figure 2. Certain

features should be particularly noted. The entire high temperature region

is platinum with minimal alumina exposure to minimize side reaction effects.

The close proximity of sample boat, thermocouple, and sampling orifice

(nozzle) ensure an essentially isothermal condition between these three key

elements. The boat support minimizes dead volume and provides flow direction, a thermal equilibration baffle behind the boat, and good control of

sample creep and vapor deposition. The water-cooled quick-connect assembly

forms a high vacuum seal to the vacuum wall in an easily dismounted joint

and allows easy cleaning of the entire sampler. During operation, the

sampler is coupled to a molecular beam High Pressure Sampling Mass Spectrometer described in detail elsewhere (1) and the skimmed supersonic beam

is carefully aligned to pass through the mass spectrometer ion source

region with no collisions', preserving species present in the sampler

essentially undisturbed.

The 2 cm spacing between nozzle and skimmer place the skimmer well

inside the first Mach disk. Calculations using

Z n

n. 2/3 D(P

q /P

1

) 1/2

n. 0.17(S

1

) 1/2 cm

gives a nozzle to Mach disk distance Z n of v3.6±0.5 cm for a nozzle diameter D of 0.006 cm, a pressure ratio across the nozzle (region 0 is sample,

region 1 is vacuum) P./P, = 10®, or an effective region 1 pumping speed

Si k 500 H/sec net.

With argon gas as a carrier in the transpiration mass spectrometer

sampler, a measurement of phase shift compared to that for molecular effusion allowed calculation of beam velocity. The beam velocities observed

during experimental runs were within 10% of the theoretical supersonic

beam velocity indicating good adherance to supersonic sampling technique.

No argon clusters were observed, but both the very small nozzle orifice

diameter and high expansion rate used here minimize such clustering.

Calibration and test runs using NaCl were made to check operation of

the sampler. The reaction equilibrium constant Kp for the reaction

NaCl(liquid) = NaCl (gas) was determined as log Kp(atm) = 4.44-8927/T. A derived second law heat of

vaporization of 41±2 kcal/mole is in good agreement with the JANAF (2)

value of 43.7 kcal/mole. This generally excellent agreement in second law

AHvapwith the JANAF tabulation confirms the conclusion that the composition of the beam generated by the sampling system is a good representation

of the gas-vapor composition in equilibrium with the condensed phase.

The vapor decomposition data for the reaction

Na

2 SC>4 ( liquid) = 2Na + S02 + 02 expressed as P(Na) are shown in figure 3. The data are in quite reasonable

agreement with the JANAF compilation (solid curve in Figure 3) and the

Knudsen data of Kohl, Sterns, and Fryburg (3) and Ficalora, et al. (4).
An ion signal corresponding to the Na2S0

4 molecule was just detected at

the upper end of our temperature range with an intensity approximately 1%

of that predicted by comparison with Knudsen data of Kohl, et al

.

(3). A

possible explanation may lie in observations by Gurvich (5) in his observations of where a temperature dependent fragmentation effect was noted

.

REFERENCES

1. Hastie, J. W. , Combustion and Flame 21, 187 (1973).

2. JANAF Thermochemical Tables, 2nd Ed., NSRDS-NBS-37 (1971).

3. Kohl, F. J., Stearns, C. A., Fryburg, G. C., NASA TM X-71641 (1975).

4. Ficalora, P. J., Uy, 0. M. , Muenow, D. W. , and Margrave, J. L. , J. Amer . Ceram. Soc. 51 , 574 (1969).

5. Gurvich, L. V. , Proceedings of the High Temperature Sciences Related

to Open-Cycle, Coal-Fired MHD Systems Conference held at Argonne

National Laboratories on April 3-6, 1977, in press.
INLET SYSTEM

To Mass

Spectrometer

PHOTOGRAPH OF SAMPLER COMPONENTS

a. Platinium sampler with nozzle

and attached skimmer

b. Boat.

c. Boat carrier.

d. Thermocouple in Al^O^ insulator

TEMPERATURE (Kelvin) 1S00 1600 1400

I0*/T (K>

FIGURE 3. Na

2S0

4 DECOMPOSITION REACTION

* observed P(Na)

solid line- JANAF tabulation

j( ographic data

FE-3800-12 SHE cT , —

‘/Te and SUBT l 1 LE

"MATERIALS RESEARCH FOR CLEAN UTILIZATION OF COAL"

Quarterly Progress Report, April 1 - June 30, 1977

S. Publication Date July 1977

6. Performing Organization Code

uesifl 77- fa.<&

/tTauthorcs) Samuel J. Schneider, Jr.

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/! ask/'&ork Unit No.

11. Contract/Grant No. E(49-1)-380Q

"12. Sponsoring Organization Name and Complete Address (Street, City, State, Lir)

Energy Research and Development Administration

20 Massachusetts Avenue, N.W.

Washington, D. C. 20545

13. type of Keport & B’ertoo Covered Quarterly

Progress Report

14. Sponsoring Agency Code

Dist. Cat. UC-90C

15. SUPPLEMENTARY NOTES

'16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a sign.ticant

bibliography or literature survey, mention it here.)

This progress report covers work on metal corrosion, metal erosion, ceramic

deformation, fracture, erosion, and chemical degradation as related to coal

gasification systems. This report/Also covers the failure avoidance program

for EKDA coal conversion pilot plants.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unle P ^ name; separated by semicolons) Ceramic corrosion, ceramic erosion, ceramic fracture, chemic

degradation, coal gasification material, failure avoidance, metal corrosion,

metal erosion, and vaporization processes

18. AVAILABILITY |

' Unlimited

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submit to NTIS; ERDA-FE will submit after approval.

I—I Order From Sup. of Doc., U.S. Government Printing Office

Washington, D.C. 20402, SD Cat. No. 03 —

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