&EPA
United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
EPA-600/7-80-046a
March 1980
Coal Gasification/Gas
Cleanup Test Facility:
Volume I. Description
and Operation
Interagency
Energy/Environment
R&D Program Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide range of energy-related environ-
mental issues.
EPA REVIEW NOTICE
This report has been reviewed by the participating Federal Agencies, and approved
for publication. Approval does not signify that the contents necessarily reflect
the views and policies of the Government, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/7-80-046a
March 1980
Coal Gasification/Gas Cleanup
Test Facility: Volume I.
Description and Operation
by
J.K. Ferrell, R.M. Felder, R.W. Rousseau,
J.C. McCue, R.M. Kelly, and W.E. Willis
North Carolina State University
Department of Chemical Engineering
Raleigh, North Carolina 27650
Grant No. R804811
Program Element No. EHE623A
EPA Project Officer: Robert A. McAllister
Industrial Environmental Research Laboratory
Office of Environmental Engineering and Technology
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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CONTENTS
Introduction 1
Facility Description 2
Pilot Plant 2
Gasifier-Particulates Condensables and Solubles (PCS)
System Description 3
Gasifier Start-up and Operation 16
Acid Gas Removal System (AGRS)— - - - 19
AGRS Start-up and Operation • 32
Alarm and Safety System 35
Data Acquisition System . 36
Laboratory Facilities and Analytical Program 39
Laboratory Facilities 39
Sampling and Sample Preservation 41
Description of Analytical Methods and Procedures Used 42
Ash Analysis 45
Ultimate Analysis .45
Carbon and Hydrogen Analysis 45
Sulfur Analysis— 45
Nitrogen Analysis 46
Gas Analysis 46
Wastewater Analysis 47
Ammonia 47
Nitrogen Analysis 48
Cyanate Analysis 48
Cyanide Analysis 48
Chemical Oxygen Demand Analysis . 48
Thiocyanate Analysis 48
Phenolics Analysis 49
Residue Analysis 49
Sulfide Anal sis 49
Total Carbon, Total Organic Carbon, and
Volatile Carbon Analyses 49
pH Determination 49
Chloride, Sulfite, Sulfate, and Fluoride Analyses 50
Sulfur Analysis in Wastewater 50
-------
Additional Facilities 51
Coal Research Laboratory 51
Vapor-Liquid Phase Equilibrium Laboratory 53
Operation and Results 54
Gasifier-PCS System — 54
Acid Gas Removal System 61
References 68
Appendices 69
Appendix I 70
Appendix II—- 86
Appendix III 96
Appendix IV Factors for Unit Conversions 99
ii
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FIGURES
Number Page
1 Utilities System -- - ----4
2 Gasifier-PCS System — 5
3 Acid Gas Removal System 6
4 Gasifier Feed Streams 7
5 Gasifier-PCS System - - — 9
6 Fluidized Bed Reactor 11
7 Cyclone Sample Train 14
8 Dehydrators 15
9 Absorbei 21
10 Flash Tank - - - - 22
11 Stripper 23
12 Start-up Tank, Pumps 24
13 Compressor 25
14 Syngas System 31
15 Data Acquisition and Laboratory Computer System 37
16 Gasifier-PCS Run GO-28 - - 60
17 Column Temperature Profiles and Mass Balances 63
18 AGRS Run AMI-13 65
ill
-------
TABLES
Number Page
1 Process Control for Gasifier-PCS System 17
2 Process Control for the Acid Gas Removal System 33
3 Analytical Program Summary 43
4 Aqueous Sample Preservation 44
5 Summary of Atomic Absorption Analysis Parameters 52
6 Run GO-28- - - - 56
7 Run GO-28 59
8 Run GO-28 62
9 Run A-M-13 - 67
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INTRODUCTION
As a part of a comprehensive long-term program to evaluate the environ-
mental effects of the production of gaseous and liquid fuels from coal, the
U. S. Environmental Protection Agency is sponsoring a major research program
at North Carolina State University. As a part of the Synthetic Fuels Pro-
gram, the project is managed by the Industrial Environmental Research Labo-
ratory in Research Triangle Park, North Carolina. The research is carried
out by faculty, students and staff of the Chemical Engineering Department of
NCSU.
The overall objective of the Project is to characterize completely the
gaseous and condensed phase emissions from a coal gasification-gas cleaning
process, and to determine how emission rates of various pollutants and pro-
cess catalyst poisons depend on process parameters. For the early stages
of the program, the major emphasis is on the formation and removal of sulfur
gases, nitrogen gases and several of the more volatile of the trace metal
elements.
In order to satisfy the research objectives in as realistic a manner as
possible, the facility used is a small but complete coal gasification-gas
cleaning pilot plant. The principal components of the plant are a continu-
ous fluidized bed gasifier; a cyclone separator and a venturi scrubber for
removing particulates, condensables, and water-soluble species from the raw
synthesis gas; and an absorber, stripper, and flash tank for acid gas re-
moval and solvent regeneration. The gasifier operates at pressures up to
800 kPa (100 psig), has a capacity of 23 kg coal/hr (50 Ib/hr), and runs
with either steam-air or steam-02 feed mixtures. The acid gas removal sys-
tem is modular in design, so that alternative absorption processes may be
-------
evaluated. Associated with the plant are facilities for direct digital con-
trol of all process systems and on-line data acquisition, logging, and graph-
ical display. Facilities for sampling and exhaustive chemical analysis of
all solid, liquid, and gaseous feed and effluent streams are also available.
The purpose of this report is to present a detailed description of the
facility, a discussion of its operation, and a discussion of the results of
a typical run carried out on August 14, 1979, using a Western Kentucky coal
char.
FACILITY DESCRIPTION
The facility consists of the pilot plant, several analytical labora-
tories, and a data acquisition and data reduction computer system. These
facilities will be described in the sections that follow.
PILOT PLANT
The pilot plant is designed so that it may be operated as two separate
units. The gasifier and particulates, condensables and solubles (PCS) re-
moval system may be operated as a unit with the gas produced going directly
to a gas disposal flare. The acid gas removal system (AGRS) may be operated
as a unit using a feed gas made up by mixing various gases in a gas mixing
manifold. The entire system may be also operated as an Integrated unit with
a portion of the gas produced in the gasifier used as feed gas to the AGRS.
In all cases, gaseous effluent streams are combined in a vent gas header and
sent to the flare for disposal.
Simplified, schematic diagrams of the plant are shown in Figures 1
-------
through 3. Figure 1 shows a diagram of the gas feed utilities system which
is used to provide preheated gas to the gasifier and also to provide a mix-
ture of gases to the AGRS when it is operated as a separate unit. Figures
2 and 3 are diagrams of the gasif1er-PCS system and the AGRS, respectively.
The remainder of this section will be devoted to a detailed description
of the pilot plant facility.
Gasifier-PCS System Description
A detailed schematic diagram of the utilities system, which provides
preheated gases to the gasifier is shown in Figure 4. Saturated steam at
150 psig is available from the University Power Plant. The steam flow rate
is indicated by FT-115, using an orifice meter, and is controlled by FCV-
115. The steam is superheated in an electrically heated superheater, H-14,
to approximately 1,000°F. Manual valves, V-140 and V-141 provide a means
for bypassing the steam to a condenser during gasifier start-up and for cal-
bration of FT-115.
Oxygen flow (or air flow) is indicated by FT-114, using a laminar flow
element, and is controlled by FCV-114. Nitrogen flow is Indicated by FT-
116, using a laminar flow element, and is controlled by FCV-116. The Ng
and 02 (or air) streams combine and are preheated to approximately 1,000°F
in an electrically heated preheater, H-13. The superheated steam and the
preheated gases combine before being fed to the gasifier.
The maximum oxygen consumption during gasifier operation is less than
5 SCFM (32°F and 1 atm.) and a manifold of six cylinders provides an adequate
supply. Nitrogen for the entire plant is supplied by a 6,000-gallon liquid
nitrogen tank and vaporizer system.
All three flow meters are calibrated in place and at pressures very
3
-------
»2
A
A
A
STEAM
>
GASIFIER
PRE- HEATER
X
SUPER-HEATER
BY-PASS
DRAIN
Figure 1
Utilities System
-------
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Figure 2
Gastfier-PGS Sy&tem
-------
SOUR
SYN
GAS
GAS
DEHYDRATOR
o>
I
CD—
SOUR GAS
COMPRESSOR
HEATER
EXCHANGER
SWEET
GAS
ACID
GAS
Figure 3
Acid Gas Removal System
-------
V-141
V-140
Calibrate*
TT-14OQ—
PI-115
150 PSIG
Steam.
AOV-115 PCV-11S
T-14
V-321
Steam
Superheater
FT-115 TT-115
r-O—i O FQV-115
ii !
To
Gatlftor
TT-130
H-14
TT-132
O-
Pre-neater
H-13
Separator
frlST-i
'V-327
»Drain
PT-114 TH114 FT-114
Oxygm
or
Air
& f 9 99 r0-;
— W — N— (XI — o — W — N — [XH-rK^c^^
PCV-101 V-237 AOV-110 F-10 PCV-110 CV-751 V-232 A LFE-114
FCV-114
AOV-117 „-
114
TT-11
Procaaa
Nttrogan
r-116
i
AOV-116 F-116 J^ LFE-116 FCV-116
r-116
Figure 4
jQasifier Feed Streams
-------
near to normal operating pressures. In addition, temperature and pressure
transmitters located at each flow meter make it possible for the data ac-
quisition system computer to correct the calibration and compute a true
mass flow rate for each of the gas feed streams.
Figure 5 is a detailed schematic diagram of the gasifier-PCS system.
Hydraulic drive motors, P-01 and P-02, power the coal feed and char extrac-
tor screw conveying systems. Coal from the feed hopper, T-01, enters the
fluidized bed gasifier from above with the feed rate controlled at the main
control panel. The screw used in feeding the coal is calibrated and the
calibration is checked after each run to account for changing capacity due
to wear. The char is removed from the gasifier through a similar system
into char receiver. T-G2. Again, the removal screw calibration is frequently
checked to account for changes due to wear. The speed of the hydraulic
motors, and thus of the feed and removal screws, is controlled by regulating
the flow of hydraulic fluid to the motor. Both screw speeds are controlled
automatically at the main control panel, with the desired revolutions per
minute (RPM) as the set point. In addition to an RPM display, a total rev-
olution counter is provided for each screw. For a run, the total weight
of coal fed divided by the total revolutions of the feed screw provides a
check on the screw feed calibration.
A nuclear level gauge capable of detecting the top of the fluidized
bed, is mounted on the outside of the gasifier shell. The operator sets
the feed rate of the coal by setting the RPM of the feed screw and then
adjusts the removal rate to maintain the fluidized bed height in a 2-inch
window as measured by the nuclear level gauge. The nuclear level gauge can
be set at various heights to permit flexibility in gasifier operating con-
ditions.
8
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To Pressure
(D
Process N2(§
Feed
Hopper
V-325
R*D purge
-DKMD
TT-293Q
sx-iQ—
AOV-213IJ-
IT-21 I Cyclone 4
Receiver
HydrauHc
Drive
CV-721 TCV-271
V-501
RAD
PSV-
—CXHXHcv-
AOV-241 V-241 >24B
HydrauHc
Drive
CV-
—OTI-252
Cher j-02
Receiver
Feed Stream
From Gasffler
F-26
CV-722
.Figure 5
Gasifier-PCS System
V-583
P-25
Discharge
Pump
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The preheated gases and the superheated steam are fed to the gasifier
through three feed nozzles arranged triangularly in the lower section of
the reactor. At each feed nozzle, a small orifice causes the feed gas to
form a jet into the fluidized bed to promote good mixing in the lower por-
tion of the bed where most of the reaction with oxygen takes place. A
short, diverging cone follows each orifice to prevent solids build-up on
the metal parts near the orifice.
The feed coal is fluidized above the cones and the gasifier char is
removed into the char receiver. The gasifier operates at a nominal pres-
sure of 100 psig.
Several nitrogen purge streams are used. Both the feed hopper, T-01,
and char receiver, T-02, are purged with nitrogen through rotameters 1 and
4, respectively, to equalize pressures and to prevent any steam from con-
densing inside the two hoppers. The feed screw is also purged through
rotameter 2 for the same reason. The reactor shell is purged through rota-
meter 3 to prevent any build-up of water or other condensables in this sec-
tion. Where applicable, all purge streams are accounted for in the mass
balance calculation.
A drawing of the gasifier reactor, feed hopper, and char receiver is
shown in Figure 6. In addition to the details shown on the drawing, the
thermowell contains six thermocouples with temperature transmitters, making
them available to the data acquisition system. The thermocouples are lo-
cated 5, 10, 25, 35, 45, and 55 inches above the gas feed nozzles. The
10-inch thermocouple, TT-201, is currently used for reactor temperature
control.
Pressure taps are located in the fluidized bed at distances 15 and
35 inches above the gas feed nozzles (20 inches apart). The differential
10
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FEED HOPPER
22 cu. ft
20 in. diometer
Schedule 80 pipe,
Corbon Steel
FEED
SCREW
24 in. diometer
Schedule 80 pipe,
Carbon Steel
Fiberfrox Bulk Ceramic
Insulation
Packed to 25 Ib/ft
Reaction Tube
6 tn diometer. Schedule 4O
316 Stainless steel
PiP«.
Thermowell
Feed Gas
Nozzle
CHAR REMOVAL
SCREW
= Gas Inlet
CHAR RECEIVER
18 cu. (t.
24 in. diameter
Schedule 80 pipe,
Corbon Steel
Figure 6
Fluidized Bed Reactor
11
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pressure, DPT-201, is also available at the control panel and to the data
acquisition system. Gas sample taps may also be installed at any location
1n or above the fluidized bed. The thermowell, differential pressure, and
gas sample lines exit through the reactor top flange.
The raw gases exiting the gasifier may be sampled at V-351 before en-
tering the cyclone, CY-21. Most of the particulates in the gas stream are
removed in the cyclone and are collected in a pressurized receiver, T-31,
for later sampling. At the present time, a thermocouple and temperature
transmitter are located at V-351 to monitor the cyclone temperature.
Following the cyclone 1s a gas sampling train, marked B on Figure 5.
This sampling train will be described later. Next, the gas passes through
a venturi scrubbing system, S-23, to quench the gas and remove most of the
solubles and condensables. The pressure drop through the scrubber is mea-
sured at DPT-232. The pressure drop across the Injection nozzle to the
scrubber is measured at DPT-231.
Water to the scrubber can be either fresh water from the building
supply or recycled water from T-25. Fresh water can be fed to the nozzle
through AOV-241 and V-241 with V-566 closed. This water is then pumped
by the scrub water pump, P-24, a positive displacement pump, to the noz-
zle of the scrubbing system. The water containing solubles and condensa-
bles (along with some fine particulates) passes through the inlet heat
exchanger, E-27A, to the PCS tank, T-25, where the water is later drained
through the discharge pump, P-25, and filter, F-26, to disposal. This
material can be sampled through V-25. Alternatively, the material drained
to the PCS tank can be recycled to the nozzle through V-566 at the scrub
water pump, P-24. This mode is particularly useful in watching the build-
up of various compounds of interest over the period of the run. The re-
12
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cycle stream can be sampled at V-324.
The sour gas leaving the PCS tank is further cooled in outlet heat
exchanger, E-27B, to remove any residual condensables. A mist eliminator,
F-27, and a series of filters, F-l, 2, 3, are used to insure that all fine
particles are removed before leaving the PCS system. Two coalescing fil-
ters, F-l and F-2, are used with only one filter being in-line at any time.
As the pressure drop across the filter increases, DPT-291, the other filter
can be switched in-line while the plugged filter is being reconditioned.
The sour gases can be sampled manually at V-325 before being sent to
the Acid Gas Removal System. The on-line analytical equipment is used to
monitor oxygen level and gas composition by a small, continuous gas stream
at SX-1. The sour gas flow rate is measured by an orifice meter and flow
transmitter, FT-293.
A gas sampling train is located just downstream of the cyclone; a
schematic diagram is shown in Figure 7. The sampling train continuously
withdraws a small gas stream (25 SCFH) from the cyclone exit through a
condenser and filter to provide a cool, dried gas stream and a sample of
condensate. After the gas has been conditioned, both high and low pressure
gas sample ports are available. The sample train also provides a gravi-
metric measure of the water in the gasifier effluent by measuring the dry
gas flow rate with a test meter, and the condensate flow rate.
Pressure control for the gasifier-PCS system is accomplished by con-
trolling the flow of sour gas at PCV-310, shown on Figure 8. Since the
gas volume of the gasifier-PCS system is approximately 90 cubic feet and
the pressure sensor, PT-310, is located near the control valve, good pres-
sure control usually means that the sour gas flow rate, as measured by FT-
13
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Figure 7
Cyclone Sample Train
HEAT
TRACING
RAW GAS
SAMPLING
PORT
CYCLONE
COOLING
WATER
SIGHT
GLASS
->TO PCS
REMOVAL
SYSTEM
V
$ur ___
SPIRAL
EAT EXCHANGER
FLOW
CONTROLLER
->COOLING
WATER
ROTAMETER-
VENT
LOW PRESSURE
SAMPLING PORT
WATER
SAMPLE PORT
HIGH PRESSURE
SAMPLING PORT
FILTER & DEMISTER
CONDENSATE TRAP
-------
Figure 8
DEHYDRATORS
pJ>T-310
Process N2 Pf9e N2 From y ~
Saslfier I rsMpCV-3™
CV-70O
V-562
309~0-AAOV-305
1V-221
AOV-310
CV-781
0«hydrator
CV-783
Syngas Supply
Purge N2
[X] D%-
D-31A
"d
FI-241
Rotam*t*r
V-241 FCV-242
DPT-315
--o—
-txj-
V-368
D-31B
O
To R«litf &
Oi«po««l
D«hydrator
F-33
[V-331
''Drain
To Compressor
-------
293, does not hold constant, but changes in response to controller action.
On the detailed schematic diagrams, all process variable sensors shown
with the letter T in the label, for example, PT-310, transmit a signal to
the control panel and are available to the data acquisition system.
The process control scheme for the gasifier-PCS system is shown in
Table I. With the exception of the coal feed and removal screws, which are
controlled by independent solid state controllers, all process control is
by a Honeywell, TDC-2000 digital control system.
The entire plant, including the gasifier-PCS system, is provided with
a number of locations where nitrogen may be introduced into the system
and a number of locations for venting the system to the flare. There are
several alarm conditions which cause an automatic vent and nitrogen purge
of the entire plant. The alarm and safety system for the entire plant is
described in a later section of this report.
Gasifier Start-up and Operation
During start-up, the gasifier-PCS system is pressurized to 100 psig
by starting a flow of process nitrogen through the gas feed preheater.
The preheater controller is set at 1,000°F and the pressure controller
at 100 psig. Since the total volume of the gasifier-PCS system is approxi-
mately 90 cubic feet, the time required to pressurize the system is also
used to start preheating the reactor vessel by the flow of hot nitrogen.
Coal feed is started when the reactor bed temperature reaches about 400°F
while maintaining a nitrogen flow sufficient to fluidlze the bed as it is
formed. During this time, a steam flow is started through the steam super-
heater, also set at 1,000°F, and through the bypass around the reactor.
Several process variables are shown plotted versus time during part of the
start-up period for run GO-28 in Figure 16.
16
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Table I. Process Control for Gasifier-PCS System
Control
Variable
Steam Flow
Oxygen Flow
Nitrogen Flow
Steam, Inlet
Temperature
Gas Inlet
Temperature
Gasifier
Temperature
Gasifier
Pressure
Coal Feed
Screw
Char Removal
Screw
Sensor
Transmitter
FT-115
FT-114
FT-116
TT-140
TT-130
TT-201
PT-310
RPM-01
RPM-02
Control
Element
FCV-115
FCV-114
FCV-116
Heater Element
H-14
Heater Element
H-14
Cascade to 02
Flow Control
FCV-310
Hydraulic Fluid
Flow Control Valve
Hydraulic Fluid
Flow Control Valve
Controller
TDC-2000
TDC-2000
TDC-2000
TDC-2000
TDC-2000
TDC-2000
TD-2000
Barber-Col man 520
Solid State Controller
Berber-Colman 520
Solid State Controller
When the bed temperature has reached approximately 700°F, and with
the bed height between 20 and 30 inches, a small flow of oxygen is started.
At this temperature, the bed will almost always ignite and after igni-
tion, the bed temperature is brought to approximately 1,450°F by slowly
increasing oxygen flow. At this temperature, steam flow is introduced
by switching an established small flow of superheated steam at 1,000°F
into the reactor by closing V-140, allowing the steam pressure in the
superheater to build up to 110 psig, and opening V-141. To achieve the
desired steady state conditions, nitrogen flow is gradually decreased,
17
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steam flow is increased, and oxygen flow is adjusted to maintain the reac-
tor temperature at the desired value. All of the above changes must be
done smoothly, and good results have been achieved by making adjustments
so that only gradual changes in the calculated superficial gas velocity,
and reactor temperatures occur.
The steady state coal feed rate is established by controlling the
speed of the coal feed screw to maintain the desired feed rate, and ad-
justing the removal screw speed to maintain the desired bed height as
indicated by the bed level gauge. During the start-up phase, the bed
height can be followed very well by the temperature sensors located in
the bed, by the bed differential pressure measurement, and by the nuclear
level gauge. During every change made during start-up, all of the varia-
bles, with the exception of the reactor temperature, are in automatic con-
trol and changes are made by changing set points. When near steady state
conditions have been achieved, the reactor temperature is put in automatic
control by cascading the temperature control loop to the set point of the
oxygen flow control loop. Experience with this method of reactor tempera-
ture control has been very good.
When the bed is well fluidized, the process described above works very
well and reactor start-up is fast and smooth. For a variety of reasons,
the bed is often not well fluidized during the start-up period and a variety
of difficulties can occur. The most probable causes and effects are hot
spots due to poor mixing in the bed, a dense bed which may be lifted to the
top of the reactor, and probably, many others. It should be noted that
where a good steady state is obtained, the operation is very stable and can-
not be easily upset. A possible reason for the difficulty of operation dur-
18
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ing start-up, and ease of operation during steady state, is the difference
in the manner in which the fluidizing gas velocity is generated. During
start-up, with no reaction in the bed, all of the fluidizing gas emerges
from the three feed nozzles and may not be well distributed. During opera-
tion, the carbon-steam reaction results in an increase in the volume flow
of gas and the carbon-oxygen reaction increases the gas temperature in a
zone just above the cones. Both of these factors act to provide a fluid-
izing gas velocity within the bed and with good distribution across the
bed. Both the start-up and the steady state operations of one run, GO-28,
will be discussed later in this report.
Complete startup and operating procedures and checklists, are given
in Appendix I in outline form.
Acid Gas Removal System
The major components of the Acid Gas Removal System (AGRS) are an
absorbing column, a flash tank and a stripping column, with the accompany-
ing auxiliary equipment to permit operation using a number of different
absorbing solvent systems. The system has sufficient flexibility to operate
using at least four solvents, methyl alcohol, dimethylether of polyethy-
leneglycol (DMPEG), hot potasium carbonate, and monoethanolamine. Detailed
schematic diagrams of the AGRS are given in Figures 8 through 14.
The system will be described by first following through the liquid
solvent circuit, and then following the gas streams.
Regenerated solvent enters the absorber, C-34, at one of three points,
depending upon the number of sections of packing to be used in a given set
of experiments. The solvent inlet temperature is measured at TT-349A.
The solvent flows down the column contacting the gas flow in either one,
19
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two, or three 7-foot sections of 1/4" ceramic Intalox saddles. Two sol-
vent sample ports are located within each section of packing; sample points
are located to reduce end effects. The temperature profile in the column
is available from two temperature transmitters in each packed section.
The pressure drop across the column packing is monitored by DPT-340 and
column pressure is measured at PT-345.
The acid gas-rich solvent drains into an absorber bottoms reservoir
where the liquid level, LT-341, is controlled by LCV-341 located at the
flash tank entrance. Before entering the flash tank, T-35, the solvent
can be routed through a filter, F-31, if necessary. The solvent can be
sampled manually prior to the filter (or the filter bypass). Pressure
drop around the filter is measured at DPT-310. After passing through the
filter (or bypassing the filter through V-526), the solvent enters the flasti
tank through LCV-341. Flash tank pressure is measured at PT-353. Level in
the flash tank Is regulated by LCV-351, at the stripper inlet, which re-
ceives its signal from LT-351 at the flash tank. It is also possible to
by-pass the flash tank using valve V-529. When operated in this manner
the liquid level in the absorber is regulated using LCV-351 at the stripper.
The solvent leaving the flash tank can be sampled manually and its tempera-
ture is measured by TT-375.
The solvent leaving the flash tank will take one of a number of routes
depending upon the solvent system being used:
(1) Methanol: The solvent leaving the flash tank is passed through the
Lean/Rich exchanger, E-37, before entering the stripper,
C-39. Here, the rich methanol exiting the flash tank ex-
changes heat with the lean methanol leaving the stripper.
This warms the inlet methanol to the stripper for better
20
-------
Figure 9
ABSORBER
V-223
ro
Refrigeration
System AV-244
E-35
\ /—QTT-345
MEA AOV-360 V-110
V"
/\ —OTT-346 (^DPT-340
LT-341
R ) To Filter
Flash Tank
Drain
-------
Figure 10
FLASH TANK
RP-31O
Ri
1
RID Vent
V-488
CV- AOV-3S8 V-448
CV-770 PCV-352 V-248
I F-31
to
/-536V
Flter
QoPT-310
V-527
LV-52B
V-525N
DHXh-
V-334
Start-up
Tank
From Absortaar
V-526
From ReboHer
Stripper
RAO
PSV-356
FlaahTank
FOH TT- PT-
358 358 358
r-
R*D
LFE-358
V-248 PCV-3S1 CV-775
AOV-352
—osx-'
To Trim H«at*r
AOV-f
341.
LSH
O
LSL
' LCV-
T-35")
LG-
350
'PAH-3S3
JPT-35
'Drain
©
V-537
Trim H«at*r
- — — — T I
QtT-351 Vv-534
V-538
V-535
35 x~x
I±-(T)TO Stripper
To Solvent Pump
0
V-593
Lean/Rich v -0
Exchanger v-594
-{Xr
V-595
-------
Figure 11
STRIPPER
FT-371Q LFE-371
(Condenser
150 PSI6
Steam
RAD
V-156
(Shell Drain)
E-
38
381
Cooling
Water KXI
l/NJvI,
N—1x3—*»
LCV-
,0V-
'370
H^HXl
-371
CV-774
OPT-371
AOV-351 V-451
\/
/\
LCV-351B
LCV-351C
CV-773 ."P. Y-449
Purga N2
,AOV-307
CjJ Procetj
From Flaah Tank ,
L/R Exchanger,
Trim Heater
.
TT-390
C-39
Stripper
OTT"391
—Qrr-392
\ /
112
•In fT-&H
CV-705 V-157 rO'i
TT-399Q-
PI-399Q 1
FCV-392(^
/ \-QTT-394
\ /—QTT-395
/ \ —QTT-396
'-182
T-398
150 PSIG
SUarn
V-165
V-162
Vv354
^HXF
Mak*-UP
Watar
To L/R Exchanger,,..
Start-up Pump
-------
From
L/R Exchanger
to
PI-354A
M Kh
T-32
r-N-O-
V-S87 CV-35A I CV-35B Surge
A
PI-354
Bottle
Drain
V-549
V-541
-X]—>
V-354
®To
Gas Chiller f
Refrigerator,
Absorber,
Trim Heater
Local ^7
Flow l-Xv-363
Control
PCV-375
-365
(>l-36
I f^ I
tart-up CV-787
Pump
V-547
fV-193
{X] Make-up Solvent
Drain
V-588
r-191
[V-588
Start-up Tank! T-36
Drain ^ t"Sj
V-S15
V-192,
To Reboiler
V-36
>rain
From Reboiler
Figure 12
Start-Up Tank, Purop«
-------
Figure 13
COMPRESSOR
DEHVORATORS
r i «
P*" W T
N>
01
PIC-321 A
&
«v-32i
-3211
PIC 351B
0™
ABSORBER
DRAIN
-1006
V- 1014
,-'-6"-'-,
vbv-io<>4
VMEON
^INJECTION
V-1013
»-321
1O03
/-1016
R&0
DRAIN
> DRAIN
TO TRW HEATER
OR MEA COOLER
-------
regeneration and, at the same time, takes advantage of the
desorption endotherm to reduce the cooling load for the
refrigeration system.
(2) DMPEG: The solvent leaving the flash tank by-passes the L/R ex-
changer through V-557, V-531 and is introduced directly
into the stripper.
(3) Hot Here, also, the solvent enters the stripper directly and
K2C03:
does not pass through the L/R exchanger, E-37.
(4) Monoetha- The solvent from the flash tank passes through the L/R
nolamine:
exchanger, exchanging heat with the material from the
stripper bottoms. This reduces the heating load for the
steam stripping process while cooling the stripper bottoms.
The solvent from any of the processes enters the stripper, C-39, at
one of three points, depending upon the number of sections of packing to
be used for mass transfer. Flow rate to the stripper is controlled by
LCV-351 A, B, or C, the liquid level controller for the flash tank, T-35.
The solvent flows down the column either contacting the stripping gas flow
for the methanol or DMPEG systems or rebelled vapor for monoethanol amine
and KgCOj systems. Both regenerative modes take place over 7-foot sections
of 1/4-inch ceramic Intalox saddles. In the physical solvent systems
(methanol and DMPEG), the stripping N2 flow originates from AOV-393 and is
metered 1n through a digital valve, DV-393, Into the bottom of the column
packing. In the chemical solvent systems (ICjCOg and MEA), 150-psig steam
1s used for rebelling, E-39; condensables are removed from the gas exiting
the column by E-38, the reflux condenser. Steam flow is controlled by
FCV-392. Additional steam for start-up can be added through V-182 regulated
26
-------
at PCV-398. The acid gas then passes to the flare through the appropriate
monitoring and sampling ports. The column is operated at total reflux.
The lean solvent leaving the stripper bottom will take different routes
depending upon the solvent system used. P-35, with a capacity of 2 GPM,
can deliver the solvent at pressures in excess of 500 psig to the pres-
surized absorber, C-34. It is a positive displacement pump with the pump-
ing action derived from the opening and closing of check valves 35-A and
35-B. A surge bottle is required downstream of the pump discharge, T-32,
to damp pulsations arising from pump operation. The lean solvent fed to the
pump can be sampled manually at V-530. A chemical addition pump, P-37, can
be used to meter in surfactants or other additives up-stream of the solvent
circulation pump at V-520.
To reduce the cool down time for the physical solvent systems (methanol
and DMPEG), a start-up pump is also used. This is a Viking gear pump with
a capacity of 5.6 GPM which makes better use of the cooling capacity of the
refrigeration system, E-35. Usually, this pump will be used at lower pres-
sures until the system is near operating temperature, when V-589 is closed
and V-587 and V-549 are opened to bring the solvent circulation pump, P-35,
on-line. Since the refrigeration system can handle a cooling load of 4 GPM,
the use of the start-up pump, P-35, in place of the solvent circulation pump
(with its capacity of 2 GPM) will reduce cool down time.
A 250-gallon polyethylene tank is used as a solvent storage or start-up
tank, T-36. The complete solvent inventory can be pumped to the tank after
a run to facilitate sampling, changing of the solvent system, or providing
any system makeup that is required. The condition of the solvent can also
be inspected visually.
27
-------
Gas feed streams to the Acid Gas Removal System can be initiated from one
of three sources; the gasifier, the SYNGAS system, or from a process nitro-
gen supply usually used in start-up situations. Feed gas from the gasi-
fier is sent through AOV-305 and controlled at 100 psig by venting excess
gas through PCV-310 to the flare. The same pressure control loop is used
with a SYNGAS feed by opening V-369 and closing V-546, isolating the gasi-
fier from the AGRS. When integrating the gasifier and AGRS, a process N«
stream is used to pressurize the AGRS by regulating ^ flow through PCV-308
at 100 psig. In this case, AOV-305 would be closed and V-240 open until
the AGRS is ready to accept the gasifier feed. At this point AOV-305 is
opened and V-240 is then closed. It should be pointed out that enough gas
must be produced in the gasifier so that a portion of it can be vented for
adequate pressure control at PCV-310.
The gas feed is then sent to one of a pair of dehydrating towers,
D-31, Figure 8, where any residual moisture is removed by molecular sieves.
A timed, mechanically-driven valve system diverts the flow to one tower
while the molecular sieves in the other tower are being regenerated by heat-
ing in the presence of a metered N2 flow, FCV-242. The pressure drop across
the dehydrators is measured by DPT-315 to alert operating personnel of
pluggage problems through the alarm system. The dehydrated gas is then
passed through a filter, F-33, before being sent to the compressor, C-31.
The gas enters the compressor, C-31, at 100 psig, from the low pres-
sure surge tank, T-31A. It is compressed adiabatically passing through a
high pressure surge tank, T-31B, and cooled in the aftercooler, E-31, a
double pipe heat exchanger with cooling water as the service fluid. Next
a knockout drum precedes the gas chiller, E-32, where solvent from circula-
tion pump, P-35, can be used to cool the gas further. In the methanol sys-
28
-------
tern, some solvent can be injected into the gas stream prior to the gas
chiller, through V-1004, to prevent freezing of any residual moisture.
The gas exits the gas chiller, E-32, into a surge bottle, T-33, needed to
damp the pulsations of the compressor, C-31.
Compressor operation is regulated by field controllers PIC-321A and
PIC-321B. Compressor suction and discharge pressures are maintained through
PCV-321. In normal operation, V-1014 and V-1006 are kept closed while
V-1023 is open to permit controller action. During start-up of the com-
pressor, V-1006, the manual spill back valve, is kept open until proper com-
pressor operation is noted.
Gas chiller operation is controlled through the operation of TCV-315.
Solvent flow from the circulation pump, P-35, can be diverted to the gas
chiller where TCV-315 bypasses some of the solvent flow to control gas tempera-
ture. The solvent then passes to the refrigerator, the MEA cooler or the
trim heater before beginning another cycle.
The flow of compressed sour gas to the absorber, C-34, is controlled by
FCV-315. Before entering the absorber, the gas can be manually sampled or moni-
tored for oxygen content, SX-2, and composition, SX-3, with the on-line sampling
equipment. The sweet gas exiting the absorber is released through PCV-345 and
the flow rate is measured by FT-345. Here, also, the gas can be sampled manu-
ally or monitored by the on-line equipment, SX-4. The sweet gas 1s then vented
to the flare for disposal.
Some of the acid gas and product gas removed in the absorber is released
in the flash tank, T-35. The flash tank is first pressurized with process
nitrogen through PCV-352 to approximately 140 psig. As the solvent feed to
the flasn tank begins releasing gas, the process nitrogen is turned off. The
29
-------
objective of the flashing process is to remove any co-absorbed product gas
before regenerating the solvent stream in the stripper. The flash tank gas
can be sampled manually or monitored by the on-line equipment at SX-6. Flow
rate is measured by FT-358 where a laminar flow element, LFE-358, is situated
The gas is then vented to the flare.
The solvent containing the acid gas is regenerated in the stripping col-
umn, C-39, where it is contacted with a stripping nitrogen stream metered in
through a digital valve, FCV-393. The acid gas-N2 mixture exits the stripper
through PCV-370, before which it can be sampled manually or monitored by the
on-line equipment at SX-5. The flow rate is measured by LFE-371-FT 371, and
the gas is then vented to the flare.
In order to evaluate the effectiveness of each solvent cleaning system
on specific gas mixtures, a synthetic gas mixing system (SYNGAS), shown in
Figure 14, is used. The system is capable of blending mixtures of M_, CO
hLS, and one other gas or gas mixture before metering the feed stream to the
AGRS through the dehydrators. The process nitrogen stream is metered in through
FCV-121 and measured by FT-121. This stream can be diverted into both the bot-
tom and top of the manifold, T-13, for better mixing. The CCL stream is sup-
plied from a manifold of gas cylinders and directed into the mixing manifold
through a digital valve, FCV-131, that can be set at the control panel. Be-
cause of the innocuous nature of these two gases, no purge system is used.
The HpS stream is also metered into the mixing manifold from a gas cylin-
der through PCV-141 which is upstream of a laminar flow element, LFE-141, and
PT-141. Purge N~ is available through AOV-140 in the event of any problem, a
mixed gas stream originates from a gas cylinder and its flow is measured by
FT-151 in conjunction with a laminar flow element, LFE-151. Purge N? is
30
-------
Figure 14
SYNGAS SYSTEM
FT-121
r-O~,
/T\To
f~ ^O7 Dahydrator*
AV-361
FCV-121
Proc«»« N2
V-121
AOV-131
PSL-131 PSH-131
CO2
>V-131 X7 Q O
*f CV-731 MSB T7 T I CV-732 V-3O1
w—rNh-T-c::^—oo ^covih-L^-rNj—XH
AOV-141
H2S
AOV-140
Purge N
2—|j>
PCV-141 LFE-141
f CV-733
W-—Kj-
Purg* H2.
FT-151
,- —O"-1i FCV-151 Drain
CV-738
Mixing
Manifold
T-13
1-131
PCV-151 LFE-151
-------
available through AOV-150. Some of the planned gas mixtures to be used in
this system include CO, Hp, COS, CS^, and certain mercaptans.
The SYNGAS mix is fed to the AGRS through V-369 with the gas stream pres-
sure controlled at PCV-310 by closing V-546. Final SYNGAS mixture composition
is monitored on-line at SX-3 in the feed gas line to the absorber.
Process control for the AGRS is by ten control loops on the TDC-2000,
two field controllers, and several digital valves. The solvent circulation
rate is controlled by the positive displacement solvent circulation pump. The
control scheme is shown in Table II.
On the liquid side, a flow of solvent is set by the positive displacement
solvent circulation pump which fixes the solvent flow to the absorber. The li-
quid level in the absorber bottom and the liquid level in the flash tank are
controlled, by regulating the flow from each vessel. As is common in level con-
trol situations, good level control causes a variable liquid flow to both the
flash tank and the stripper. This in turn causes a variable amount of gas to
be released in these vessels which interacts with the pressure controllers and
causes the gas flow rates from the absorber, flash tank and stripper to vary.
Good process control for the entire system was achieved by compromise and by
accepting fairly slow controller action.
AGRS Start-up and Operation
Because current experience has been with refrigerated methanol as the sol-
vent, start-up and operation for that solvent system will be described.
Initially, the absorber, flash tank and stripper are pressurized using
process nitrogen. Nitrogen is supplied to the absorber through FCV-121 for
SYNGAS runs and through V-240 for integrated runs with both streams regulated
32
-------
Table II. Process Control for Gasifier-PCS System.
Control
Variable
Feed Gas Supply
pressure
Compressor Suc-
tion Pressure
Compressor Dis-
charge Pressure
Sour Gas Flow
Rate
Absorber Pressure
Flash Tank
pressure
Stripper Pressure
Stripper Steam
Flow
Sour Gas Temp
to Absorber
jKjEA Temperature
to Absorber
Absorber Liquid
Level
Flash Tank
Liquid Level
Sensor
Transmitter
PT-310
PIC-321A
PIC-321B
FT-315
PT-345
PT-353
PT-370
TT-391
TT-315A
TT-349
LT-341
LT-351
Control
Element
PCV-310
PCV-321
PCV-321
FCV-315
PCV-345
PCV-353
PCV-370
FCV-392
TCV-315
TCV-349
LCV-341
LCV-351A
LCV-351B
LCV-351C
Controller
TDC-2000
Foxboro Pneumatic
Field Controllers
Foxboro Pneumatic
Field Controllers
TDC-2000
TDC-2000
TDC-2000
TDC-2000
TDC-2000
TDC-2000
TDC-2000
TDC-2000
TDC-2000
33
-------
by FCV-315. The pressure is initially set at 100 psig. The flash tank is
pressurized through V-248 to approximately 40 psig. The stripper is set at
10 psig using FCV-393. When all vessels are at their initial set points,
solvent is then circulated by P-35 or P-36 with level controllers LIC-341
and LIC-351 maintaining proper inventory in the absorber and flash tank and
consequently in the stripper. The refrigeration system is then turned on
with the feed temperature to the absorber set at -35°F.
After some cooling is noted, the sour gas compressor, C-31, is activated
and the pressure in the absorber is brought to the desired pressure, typical-
ly 400 to 500 psig. The flash tank pressure is then reset at 100 to 200 psig.
The system is allowed to cool down and the nitrogen supply to the flash tank
at V-248 is closed.
When the system is operating properly and sufficient cooling is noticed,
either a synthetic gas mixture or product gas from the gasifier is fed to the
system, slowly replacing the initial inert gas feed. Onset of either an ab-
sorption exotherm or a desorption endotherm signals proper operation. The sys-
tem is then allowed to approach steady state as marked by constant temperature
pressure, and flow rates in the system. Time to attain steady state is depend-
ent on the solvent recirculation rate.
Experience so far has been that the system operates extremely well in both
SYNGAS and integrated modes. Once the system is started up, little attention
is required. As previously mentioned, there was some difficulty in coordinat-
ing control loop tuning and satisfactory mass balance closure. This was the
result of very quick pressure and level control loop response to small upsets
Retuning the control loops (flash tank and stripper pressure, absorber, and
flash tank level) remedied this problem allowing for adequate control while
-------
still Insuring the availability of representative gas samples. Both the start
up and the steady state operation of one run, AMI-13, is presented later in
this report.
Complete start up and operating procedures, in outline form, are given in
Appendix I. A complete list of manual valve settings is given in Appendix II.
Alarm and Safety System
The pilot plant is equipped with an extensive alarm and automatic safety
system in order to minimize the potential hazards of the operation of the faci-
lity. Two independent systems, one for the gasifier-PCS system and one for the
AGRS system monitor signals from plant instrumentation for deviation from pre-
set alarm conditions. Once an alarm condition has been detected the system
initiates a switch selectable warning and/or shutdown procedure. In the case
of a few critical alarm situations the entire affected system undergoes an im-
mediate vent and purge. A list of the alarms and their available responses is
shown in Appendix III.
Alarms associated with the gasifier-PCS system may initiate one of six
different responses. The majority of these conditions need only activate an
audible alarm (Alarms Only Mode) to warn the operator of an alarm condition.
The location of the alarm is marked on the control panel by a red light. If
an alarm condition is considered a dangerous one, the operator may preselect
one of two other system responses. The A response calls for an immediate au-
dible alarm followed by a two-minute time delay. If the alarm condition is
not rectified within this period, all supply streams to the Gasifier-System
are shut off as well as power to the utility heaters, H-13 and H-14. The B
response initiates an audible alarm and an immediate shut down of supply
streams and heaters. Certain selected alarms considered to be intrinsically
35
-------
hazardous are hardwired to initiate a C response. This causes the gasifier
and PCS system to vent and purge immediately. Loss of feed or high element
temperature in either H-13 and H-14 causes an immediate shut down of electri-
cal power to the affected heater.
The AGRS system has four alarm responses similar to the Alarm only, A, B,
and C responses of the gasifier-PCS system. Most of the alarms may initiate
either an audible alarm only, D, E, or F response as preselected by the opera-
tor. The E response initiates an audible alarm and an immediate shut down of
the supply steams and CP-31, the sourgas compressor. The D response provides
for a two-minute delay before supply and compressor shutdown and the F response
immediately vents and purges the system. Several of the individual units in
the AGRS system, such as the sourgas compressor and the solvent chiller, have
self contained shut down systems to protect the units.
DATA ACQUISITION SYSTEM
The Data Acquisition and Laboratory computer performs two major functions
During plant operation, the system monitors plant instrumentation, providing
information to the operator and creating a permanent log of the run. At times
when the plant is not in operation the computer is used to maintain and reduce
data from the facility and from the analytical laboratories. A block diagram
of the system is shown in Figure 15.
Plant operation is monitored and regulated from a control room. Signals
from 96 sensors (temperature, pressure, flow rate, etc.) are sent to a control
panel, where they are processed and sent to a video display terminal and/or a
Honeywell TDC 2000 process control computer and/or the data acquisition system.
The TDC 2000 regulates 16 different control loops in the plant. An alarm panel
superimposed on a process schematic provides visual and auditory indications of
potentially hazardous conditions.
36
-------
96
Process
Variables
M
U
X
POP 11/34
MINICOMPUTER
Phone Link to
Other Systems
r
1 ISC-8001 |
Color
~~~F"~1
| LA-36 |
Video Teleprinter
Display
Operator's
Console
i
1 ^C \i~~ >3f "^sJ
| UT-100| |B-150| |M-200| | LA-12o|
C.R.T. Card Line
Terminals Reader Printer
Program Development
and General Purpose
i
J
Computing
Figure 15
DATA ACQUISITION AND LABORATORY COMPUTER SYSTEM
-------
The data acquisition system has two main objectives: to provide rapid,
easily read information to the operator during plant operation, and to pro-
vide a permanent record of run data. Each process instrument is wired to a
channel of an LFE Model 6100 Remote Terminal Unit. The LFE 6100, a 96 chan-
nel analog-to-digital converter, digitizes the one to five volt transmitter
signals to 12 bit resolution and transmits the results to the computer through
a serial communication line. The conversion takes place every 5 seconds upon
command from the computer.
The system is centered around a DEC PDF 11/34 minicomputer. The 16-BIT
processor supports 64,000 words of memory and 10.4 mega bytes of online disk
storage. Up to 10 users terminals may be supported. Currently the general
purpose facility consists of two video terminals, a card reader for input, and
a fast teleprinter for output. In the plant control room, a color graphics
terminal and a teleprinter form the operator's console.
The operating system used is DEC RSX-11M, an event-driven, multitasking
operating system. This gives the system the capability of supporting several
users simultaneously. The high level languages, FORTRAN IV and PLI are avail-
able along with PDP-11M MACRO ASSEMBLER for user program development.
The acquisition software is written in PLI. A primary acquisition task
receives data from the LFE-6100 at 5 second intervals, converts the data to
engineering units, and places it in a shared data region for access by the
display and logging functions. This task also maintains an hour-long, circu-
lar file of data recorded at 15 second intervals. This file, called a trend-
file, provides the data for interval averaging and online plotting.
During plant operation the operator views data on a video graphics ter-
minal. Schematic displays of different sections of the plant may be viewed;
38
-------
the displays resemble process flow sheets and include key plant variable values
updated at 5 second intervals.
Logging takes place in two ways. A hard copy report of all system vari-
ables is available on the teleprinter at operator-selected intervals, provid-
ing an immediate permanent record of the run. The data are also saved at inter-
vals on disk, and are later used as input to offline data reduction and process-
ing programs.
To analyze process trends the operator may request a plot on the video
graphics terminal of any of the process variables vs. time. Other functions,
such as snapshotting the process and rapidly calculating mass balances, are cur-
rently being developed.
LABORATORY FACILITIES AND ANALYTICAL PROGRAM
Solid, liquid, and gas samples from the pilot plant are naalyzed in four
laboratories. A summary of the analytical program is shown in Table 3. The
following sections briefly describe the facilities that are used for the analy-
ses, the equipment and instrumentation available, the sampling and sample pre-
servation procedures, and the analytical methods used. Four laboratories have
been equipped to meet the chemical analysis requirements of the project.
Laboratory Facilities
The main laboratory is a large, general purpose, laboratory in which ulti-
mate and proximate analyses of coals and chars and all the wastewater analyses
are reformed. Equipment available for these analyses include furnaces, ovens,
combustion trains, and digestion and distillation racks. Whenever possible,
ASTM (1) or APHA (2) guidelines have been used in the construction and the in-
stallation of the equipment.
39
-------
The main laboratory also houses a water deionizer and still, several
macro, semi-micro, and micro balances, glassware, reagents, and four instru-
ments for the analysis of selected pollutants in the plant wastewater Thes
instruments are a Dionex System 10 ion chromatograph, an Orion Model 901 se-
lective ionalyzer, a Dohrman DC-50 carbon analyzer, and a Baush & Lomb-Shimad
Spectronic 210 UV-Visible spectrophotometer.
The Trace Analysis Laboratory is devoted to the analysis of trace ele-
ments by atomic absorption spectrophotometry. Instruments housed in this lab
oratory include a Perkin-Elmer Model 603 atomic absorption spectrophotometer
with a deuterium arc and various types of flames, a Perkin-Elmer HGA-2200
ite furnace, a Perkin-Elmer mercury analysis system, an LFE Model LTA-504 low
temperature plasma asher, and a Barnstead water deionizer. A Varian Model 65
vapor generation device has been recently added.
The Coal Research and Analysis Laboratory is equipped for the study of
coal pyrolysis and the analysis of sulfur, nitrogen, and free-swelling index *
coals and chars. The instruments housed in this laboratory include a Fisher
Scientific Model 470 sulfur analyzer, an Antek Model 707 nitrogen analyzer, a
batch pyrolysis furnace, and a laminar flow reactor capable of operation at
temperatures up to 1273 K with particle residence times as low as 50 milljsec_
onds.
The Gas Chromatography Laboratory is equipped for the analyses of perman
ent, sulfur, and hydrocarbon gases produced in the gasification and gas clean
ing process as well as liquid solvent samples. Instruments in this laborato
include a Tracer 550 gas chromatograph equipped with a thermal conductivity
detector, a Tracer 550 gas chromatograph with a flame ionization detector
Varian 3700 gas chromatograph equipped with both thermal conductivity and fl
40
-------
photometric detectors, and a Perkin-Elmer Sigma X chromatography data sta-
tion. A Metronix Dynacalibrator is also used for certain calibrations.
Each Gas Chromatograph is equipped with both gas and liquid sampling ports.
Also, provision is made for pressure-regulated injection of either hot or
cold samples to facilitate the analysis of trace compounds present in the
AGRS solvent.
Campling and Sample Preservation
The sampling points throughout the plant are shown in the detailed sche-
matic diagrams. The sampling train is shown in Figure 7. Feed coal samples
are obtained from the storage drums before they are loaded into the gasifier
feed hopper. The spent char is sampled from the char receiver. A sampling
device is available so that samples at different depths in the receiver can
be obtained corresponding to chars from the different stages of gasifier oper-
ation.
Char fines are obtained from the cyclone hopper. Each sample is then
riffled and divided into three fractions. The first analysis fraction is
used as received for sieve and as-received moisture analysis; the second anal-
ysis fraction is ground to pass a No. 60 U. S. Standard sieve-, and the third
fraction is ground to pass a No. 200 sieve. The ground samples are equili-
brated to laboratory humidity overnight.
Gas samples are obtained from the gas sampling ports in heated, evacuated
tainless steel bombs and in cold, evacuated stainless and glass bombs. Typi-
a11y, samples are obtained from the exit of the cyclone, the sampling train,
nd the exit of. the PCS tank. Samples of feed gas and sweet gas are obtained
from the bottom and top of the absorber respectively. Samples are also collect-
4 of flash tank gas, and acid gas from the stripper.
41
-------
Wastewater samples are obtained from the PCS tank and the sampling train
These samples are immediately preserved according to the procedures shown in
Table 4, and kept refrigerated until analysis. Gas, methanol, and water sam-
ples are obtained from several absorber and stripper sampling ports.
Description of Analytical Methods and Procedures Used
After a plant run, the chemical analyses are performed according to a
schedule such that analyses are done within maximum holding times. All waste-
water holding times are shown in Table 4. Permanent gas samples can be stored
for several days. Sulfur gas samples are analyzed immediately. Solid samples
can be stored indefinitely. A brief description of the procedures used for
analysis are given below.
Sieve Analysis—
U. S. standard sieves are used; 50 to 100 grams of sample are loaded on
the top sieve and the entire assembly is shaken in a sieve shaker for 5 to 10
minutes.
AR Moisture Analysis—
ASTM-9-3173 Method is followed. Moisture is determined in the as-received
sample by establishing the loss in weight of 1.0 g of sample heated to 104° to
110°C for 1 hour in a moisture oven with bone dry air circulation.
Volatile Matter Analysis—
ASTM-D-3175 method for coke is followed. Volatile matter is determined bv
establishing the loss in weight resulting from heating 1.0 g of sample for 6 0
minutes at 950 +_ 20°C in a volatile matter furnace. Two furnaces, one control!
ed at 750 + 20°C and the other at 950 + 20°C, are available for the analysis Of
sparking coals.
42
-------
Table 3
Analytical Program Summary
Type of Sample Analyte
Solid Sieve
AR Moisture
Volatile Matter
Ash
Carbon-Hydrogen
Sulfur
Nitrogen
Gas and Solvent CO, H,,, N2, CH4,
CO,
Wastewater
H2S, COS, CS2, mer-
captans, organic
sul fides, thio-
plenes, etc.
C02, N2, N2S, solvent
C,-Cr hydrocarbons,
BTX
Ammonia
Nitrogen
Thiocyanate
Phenol ics
Residue
Sul fide
Cyanate
Cyanide
COD
TC, TOC, VC
PH
Cl", F", SOg, SOj
Sulfur
As, Be, Cd, Cr, Hg,
Ni, Pb, Sb, V
Method or Instrument
ASTM-D-3173
ASTM-D-3175
ASTM-D-3178
Fisher Model 470 Sulfur Analyzer
Antek Model 707 Nitrogen Analyzer
Varian 3700 Gas Chromotograph (TCD)
Varian 3700 Gas Chromotograph (FPD)
Tracor 550 Gas Chromotograph (TCD)
Tracor 550 Gas Chromotograph (FID)
APHA SM No. 418
APHA SM No. 421
APHA SM No. 413 K
APHA SM No. 510 A-C
APHA SM No. 208 A
APHA SM No. 428 D
APHA SM No. 413 J
ASTM-D-2036
Hach COD Reactor
Dohrman DC-50 Carbon Analyzer
Orion 901
Dionex System 10 Ion Chromatograph
Dionex System 10 Ion Chromatograph
Perkin-Elmer 603 Atomic Absorption
Spectrophotometer
43
-------
Analysis
Table 4
Aqueous Sample Preservation
Vol. Req. Container Preservative
(ml)
Holding Time
Cyanide
Cyanate
Thiocyanate
Sulfur
Ammonia
Nitrogen
COD
Phenol ics
*Carbon
*TOC
*Sulfite
*Chloride
*Sulfate
Sulfide
Trace Elements
PH
Residue
500
500
500
50
400
500
50
500
25
25
50
50
50
500
500
25
100
P,G
P,G
P,G
P,G
P,G
P,G
P,G
G only
P,G
P,G
P,G
P,G
P,G
P,G
P,G
P,G
P,G
NaOH to pH 12
NaOH to pH 12
NaOH to pH 12
NaOh to pH 12
H2S04 to pH< 2
H2S04 to pH< 2
H2S04 to pH< 2
H2S04 to pH< 2
HC1 to pH 2
HC1 to pH 2
Formaldehyde (6 drops)
None
None
Zinc Acetate (3 drops/lOOml)
NaOH to pH<12 (See Note 1)
None
24 hrs.
24 hrs.
24 hrs.
24 hrs.
24 hrs.
24 hrs.
7 days
3 days
24 hrs.
24 hrs.
<1 hr.
7 days
7 days
7 days
6 hrs.
7 days
Note 1 Bring to pH 12 with NaOH. Add 2N Zinc acetate (3 drops/100 ml
sample). Sufficient dose of zinc acetate is indicated by
testing a drop of sample on lead acetate paper moistened with
pH 4 acetate buffer (paper should turn black).
* Changes made for preservation procedure
Note 2 All samples stored at 4°C immediately after preservation
P = polyethylene
G = glass
44
-------
Ash Analysis—
ASTM-D-3174 method is followed. The ash content is determined by weigh-
ing the residue remaining after burning 1.0 g of coal at 750°C (950°C for
coke) in a muffle furnace.
Ultimate Analysis—
The feed coke and char samples ground to pass a U. S. Standard No. 60
sieve are used for C, H, and S analyses. These analyses consists of the de-
termination of carbon and hydrogen in the gaseous products of complete combus-
tion, the determination of sulfur, nitrogen, and ash in the material as a whole,
and the calculation of oxygen by difference. The individual methods are de-
scribed below.
Carbon and Hydrogen Analysis—ASTM-D-3178 method for total carbon and hy-
drogen in coal or coke is followed. The determination is made by burning 100
mg of sample in a combustion train and fixing the products of combustion in an
absorption train after complete oxidation and removal of interfering substances.
This method gives the total percentages of carbon and hydrogen in the coal
as analyzed, and includes the carbon in carbonates and the hydrogen in the mois-
ture and in the water of hydration of silicates. Benzoic acid standards are
analyzed to condition the combustion trains and to ascertain their accuracy and
reproducibility before analysis of the coal and char samples.
Sulfur Analysis—Coal and coke samples are analyzed using a Fisher Sulfur
Analyzer Model 470. The analyzer detects sulfur through an amperometric tech-
nique devised to measure S02 in the effluent produced during the combustion of
sulfur-bearing materials. The analyzer has been shown to be extremely accurate
45
-------
and precise in the analysis of sulfur in coal and coke. However, the anal-
yzer does not detect sulfate sulfur which occurs in small quantities in coal
The analyzer is calibrated with certified coal standards and its calibration
is checked periodically while the samples are run.
Nitrogen Analysis—Coal and coke samples are analyzed for nitrogen using
an Antek Model 707 microprocessor-controlled chemiluminescence detector. The
samples are pyrolyzed in a furnace and contacted with ozone. The flameless
reaction between the pyrolyzate (nitric oxide) and ozone is monitored by a
light sensitive detector. Nitrogen containing organic compounds and coal/coke
samples analyzed by the Kjeldahl-Gunning method are used as standards.
Gas Analysis--
All gas analyses are done by gas chromatography except for the determina-
tion of steam. The concentration of steam in the gas leaving the gasifier Is
determined gravimetrically using the water drained from the sampling train.
The fraction of gasifier exit gas passed through the sampling train is care-
fully metered for the calculation of the water concentration.
The pressurized gas in the sampling bombs is injected into the gas chro-
ma tographs through heat traced lines and gas sampling ports. The chromatographs
are calibrated using Heise gages to introduce known amounts of calibration
gases into the temperature-controlled sample loop. A Perkin-Elmer Sigma X data
station is used to integrate, log, and operate on the signals from the chroma-
tographs.
Permanent gases can be analyzed with either the Van'an 3700 GC or the Tra-
cor 550 GC each using a thermal conductivity detector. A 7 foot x 1/8 inch
Carbosieve S column is used in both cases to separate H2> N2> CO, CH4, H2s and
46
-------
C0?. The same Tracer 550 equipped with a 10 foot x 1/8" SS Poropak QS column
is used for the analysis of solvent samples.
Sulfur gases are analyzed for H2S, COS, C$2, mercaptans, organic sulfide,
and thiophene using the Varian 3700 with flame photometric detector. A one
foot x 1/8" Carbopak column is used for separation. Also, an 8 foot x 1/8"
Chromosil 310 column is used for separation of large amounts (greater than 500
ppm) of H2S and COS which are then analyzed with the Varian's thermal conducti-
vity detector. Solvent samples can also be injected into the FPD to determine
the amount of sulfur gases present.
Current efforts include the development of techniques for hydrocarbon
analyses with the Tracer 550 FID, (C-j-Cg, Benzene Toluene Xylyene (BTX)).
Wastewater Analysis--
Wastewater samples from the sampling train may be analyzed almost immedi-
ately to obtain information on the production of pollutants. Samples from the
PCS tank may be analyzed to obtain information on the buildup of pollutants
from the beginning of the run until the time samples are obtained.
Sampling train wastewater samples are extremely concentrated in all pol-
lutants because all the water originates from the condensation of the excess
stream from the gasifier. The PCS wastewater samples are very dilute because
150 gallons of city water are recirculated to clean the gas throughout a run.
Ammonia—Ammonia nitrogen is determined by the distillation standard me-
thod (APHA) No. 418. The sample is buffered at a pH of 9.5 to inhibit the hy-
drolysis of organic nitrogen compounds, and distilled into a solution of boric
acid where the ammonia nitrogen is determined acidimetrically with standard
sulfuric acid, using methyl red as the indicator.
47
-------
Nitrogen Ana lysis--Total Kjeldahl nitrogen is determined by standard Me-
thod No. 421. The nitrogen in 50 ml of sample is converted into ammonium
salts by destructive digestion of the sample with a hot, catalyzed mixture of
concentrated sulfuric acid and potassium sulfate. These salts are subsequent-
ly decomposed in a hot alkaline solution from which the ammonia is recovered
by distillation and determined by acidimetric titration. A sucrose blank is
always run concurrently with the samples. It should be noted that this method
does not detect nitrogen in the form of oxide, azide, axo, hydrazone, nitrate
nitrite, nitrile, nitro, nitroso, oxime, and semicarbazone.
Cyanate Analysis—The cyanate content of the samples is found by determin-
ing their ammonia content before and after hydrolysis. Standard Method No.
413J is followed. The cyanate is hydrolized by heating at a low pH using sul-
furic acid.
Cyanide Ana1ysis--ASTH-D-2036 procedure is followed for this analysis.
The procedure involves a distillation for concentrating and removing cyanides
by refluxing the sample with H2$04 and MgCl2 reagent. The liberated HCN is
collected in NaOH solution and its concentration is determined by a titrimet-
ric procedure.
Chemical Oxygen Demand Analysis—The COD of the samples is determined us-
ing a Hach COD reactor. The test uses a semimicro sample digestion method.
Two ml of wastewater are digested with sulfuric acid and potassium dichromate
The titration is performed with ferrous ammonium sulfate standard solution.
Thiocyanate—Standard Method No. 413 K is followed. The method entails
the colorimetric determination of thiocyanate after filtration and color develop-
ment with Fe (N03)3.
48
-------
phenolics—Standard Method No. 510 A-C is used. The steam distill able
phenols are reacted with 4-aminoantipyrene at a pH of 10.0 +_ 0.2 in the pre-
sence of potassium ferricyanide. The solution absorbance is then determined
photometrically using a Baush & Lomb-Shimadzu spectronic 210 UV/VIS spectro-
photometer. This method is sensitive only to a relatively small number of
phenolic compounds. A gas chromatograph with a flame ionization detector will
be used in the future for a better and detailed analysis of phenolics and BTX.
Residue Analysis—Standard Method No. 208 A is followed. A well-mixed
sample is evaporated in a weighed dish and dried to constant weight in an oven
at 103° to 105°C. The increase in weight over that of the empty dish repre-
sents the total residue, which is an arbitrary quantity defined by the proced-
ure followed.
Sulfide Analysis—Standard Method 428 D is followed. Hydrochloric acid
is added to the samples, after filtration, followed by excess iodine and starch
indicator. The excess iodine is then back-titrated with sodium thiosulfate
solution.
Total Carbon, Total Organic Carbon, and Volatile Carbon Analysis—A Dohr-
mann Model DC-50 carbon analyzer is used for these analyses. The instrument
follows a temperature program to separate the different types of carbon; then
it ozidizes the carbon to carbon dioxide. The carbon dioxide is reduced to
methane and detected with a flame ionization detector.
pH Analysis—The pH is determined using an Orion Model 901 pH meter. The
meter is calibrated using 4.0 and 7.0 pH buffer solutions.
49
-------
Chloride. Sulfite. Sulfate, and Fluoride Analyses—The wastewater sam-
ples are analyzed for these ions in a Dionex System 10 ion chromatograph.
The instrument separates the ions with an ion exchange resin and detects them
with a conductivity cell.
Sulfur Analysis in Wastewater—All sulfur species in the wastewater sam-
ples are oxidized to SO^ by heated digestion with a hot alkaline hydrogen
peroxide solution. The sulfate ion is then analyzed in the Dionex System 10
ion chromatograph.
Trace Element Analysis--
All trace element analyses are done by atomic absorption analysis using
a Perkin Elmer 603 Atomic Absorption Spectrophotometer, an HGA-2200 graphite
furnace, a cold vapor mercury analysis system and a Varian Model 65 Vaporgener-
ator. Ramp heating is used for the drying and charring steps, and normal, tem-
perature controlled, or time controlled heating is used during atomization de-
pending on the volatility of the element. Deuterium background correction is
used in all cases except in the analysis of mercury. Electrodeless discharge
lamps are used in all cases except in the analysis of Cd, V, Be, and Bi where
hollow cathode lamps are used.
The wastewater samples are digested by evaporative reflux with nitric
acid for the analysis of all the elements of interest except mercury. Raw
wastewater samples are analyzed directly for mercury. The solid samples,
which have been ground to pass a No. 60 sieve and equilibrated to laboratory
humidity, are prepared by either Parr bomb combustion or by low temperature
ashing followed by acid bomb digestion. The liquor obtained from the oxygen
bomb combustion is used for the analysis of Hg, Pb, As, Sb, and Cd. An
50
-------
LFE-LTA-504 low temperature plasma asher is used for the oxidation of the sam-
ples intended for the analysis of Cr, V, B, Ni, and optionally Pb and Cd. The
low temperature ashes are then digested in teflon-lined acid bombs. All acid
liquors are then diluted to volume. Typical sample weight to solution volume
ratios are 1 gram to 100 ml. Wastewater samples are typically concentrated
from 150 to 50 ml.
Linear calibration curves are obtained, if possible, that cover the con-
centration ranges observed for the samples. If a sample falls out of the lin-
ear range, it is generally diluted. All analyzer parameters are optimized to
give the best signal-to-noise ratio. Parameters which have been found to pro-
vide good results are listed in Table 5.
Direct calibration methods are used for the analysis of Hg, Ni, Sb, Be,
Cr, and V. The method of standard additions is used for the analysis of Pb
and As. Nickel complexation is used to allow high temperature charring during
the analysis of As. The correlation coefficients are typically greater than
0.99 for all the calibration and standard addition lines.
The vapor generation device in an alternate form of analysis for Hg, As,
and Pb when concentrations are very low or when sample matrix is not compatible
to the graphite furnace analysis.
ADDITIONAL FACILITIES
In addition to the facilities mentioned previously, there are two other
laboratories used to supplement project objectives:
Coal Research Laboratory
This laboratory contains both batch and laminar flow furnace reactors.
These are used to study the evolution of volatile matter and trace elements
51
-------
en
ro
Hg
Table 5
Summary of Atomic Absorption Analysis Parameters
Element
Cr
V
Be
Pb
Ni
As
Ct4
Dry Temp-Time
Ramp Time
°C-Sec
Sec
125-40
10
125-42
10
125-42
10
125-40
10
125-41
10
125-30
10
125-40
Char Temp - Time
Char Time
°C-Sec
Sec
1100-34
10
1700-32
10
1200-30
10
600-34
10
1000-30
10
1100-30
10
400-30
Atom Temp-Time
°C-Sec
2700-8
2800-8
2800-8
2300-8
2700-8
2700-8
?mn_R
Wavelength
nm
357.9
318.4
234.9
217.0
232.0
253.5
??a R
Slit
nm
(4) 0.7
(3) 0.2
0.7
0.7
(3) 0.2
0.7
(&\ n ?
COLD VAPOR ANALYSIS
* Dor AA seems to be off by one nanometer
-------
from pulverized coal during pyrolysis. Also, this enables the screening of
various types of coal and char prior to use in the pilot plant.
Vapor-Liquid Phase Equilibrium Laboratory
This laboratory contains equipment for the determination of vapor-liquid
equilibrium for the various solvent systems used in the AGRS. Up to this
point, work has concentrated on the determination of VLE data for the metha-
nol-COp-Ng-HgS system and the development of a predictive capability from bi-
nary phase equilibrium data for the multicomponent system.
53
-------
OPERATION AND RESULTS
In order to illustrate the operation of the pilot plant facility and
the results which can be obtained from it, a run made on August 14, 1979
will be described. For this run the gasifier-PCS-AGRS was operated as an
integrated system. The run was designated GO-28 for the gasifier-PCS sys-
tem and AMI-13 for the AGRS. It consisted of the steam-oxygen gasification
of Western Kentucky #11 coal char of 10x80 mesh size in the gasifier, and
used refrigerated methyl alcohol as the solvent in the AGRS.
The run was one of a set designed to explore ranges of operating con-
ditons using char in the gasifier and methyl alcohol in the AGRS. A fur-
ther objective was to test the ability to maintain a steady state and to
achieve closed mass balances over the entire plant. The operation and re-
sults will be described in two parts in the sections that follow.
GASIFIER-PCS SYSTEM
Operating conditions for the reactor were approximately 104 psig and
an average fluidized bed temperature of 1830°F. The char feed rate was 38
Ib/hr and the make gas flow rate at the PCS exit was 15.8 SCFM. The car-
bon conversion was 52.6%. The principal operating variables of the run,
selected output variables, and material balances are shown in Table 6.
Table 7 is a summary of the more important parameters of the run shown in
schematic form.
Several selected process variables are shown plotted versus time in
Figure 16. The two temperatures shown are those measured at 10 and 35
inches above the gas feed nozzle. Also shown is the reactor pressure
54
-------
measured at the reactor top, PT-213, the product gas flow rate at the PCS
exit, FT-293, and the differential pressure between two pressure taps in
the fluidized bed, located 20 inches apart, DPT-21.
During the reactor startup period, 06:00 a.m. to about 11:00, several
upsets occurred which resulted in excursions of bed differential pressure,
temperatures, etc. Once a steady state was achieved, however, all process
variables remained very steady and the system operated under automatic con-
trol without any problems.
Gas samples were taken at 14:30 for the gasifier-PCS system only and
were taken for the entire system at 16:30 and 17:30. For the gasifier-PCS
system, at each sample time, samples were taken at the following locations:
1. At the PCS exit, near SX-1, in stainless steel bombs at 100 psig.
2. After the cyclone, from the sample train, in stainless steel bombs
at 100 psig.
3. After the cyclone, from the sample train, in glass bombs at 20
psig. These bombs are mainly for sulfur gas analysis.
The residence time of the reactor-cyclone, PCS tank system is such
that after approximately 90 minutes, the gas composition from samples taken
at the sample train and the PCS exit are essentially identical. The experi-
mental time constant for the PCS tank at 100 SCFM is 24 minutes. From
Figure 16 1t can be seen that steady state conditions were achieved at about
11:00. The values of the process variables used in Tables 6 and 7 are aver-
ages over the period 12:30 to 17:30. The gas analysis shown in the tables
is the average of the three samples times noted on Figure 16.
As can be seen from Table 6, the mass balance closures for total mass
and the major elements is excellent and indicates that flow rate measurements
55
-------
Table 6
mmmmmmwttmtmmmmtttt
{ NCSU DEPARTMENT OF CHEMICAL ENGINEERING |
* FLUIDIZED BED COAL GASIFICATION REACTOR I
t t
RUN 60-28 8/14/79 12530-17J30
REACTOR SPECIFICATIONS
PRESSURE = 104.0 PSI6 ( 818.4 KPA)
TEMPERATURE = 1830.0 DEG.F ( 998.9 DEG.C)
ESTIMATED BED VOIDAGE = 0.75
BED EXPAHSIOK FACTOR = 1,65
ESTIMATED LEAK RATE = 0.79 SCFM
SOLID FEED PROPERTIES
WESTERN KENTUCKY til COAL CHAR. 10X80 MESH
HOffSbn : '12.1 H4R8
AVERAGE PARTICLE DIAMETER = 493.8S MICRONS
A-R MOISTURE CONTENT = 0.0108
PROXIMATE ANALYSIS OF COAL FEED
FIXED CARBON = 0.839
VOLATILE HATTER * 0.022
MOISTURE » 0.011
ASH - 0.127
ULTIMATE ANALYSES
COAL FEED SPENT CHAR CYCLONE DUST
CARBON 0.813
HYDROGEN 0.004
OXYGEN 0.018
NITROGEN 0.010
SULFUR 0.026
ASH 0.127
0.726
0.002
0.015
0.001
0.016
0.240
0.624
0.003
0.009
0.010
0.015
0.340
FEED RATES
FEED RATIOS AND CONDITIONS
COAL - 38.16 LB/HR AT 200.0 DEG.F
= 17.31 KG/HR AT 93.3 DEG.C
STEAM = 59.59 LB/HR AT 365.3 K6.F
= 27.03 KG/HR AT 185.2 DEG.C
OXYGEN -- 16.26 LB/HR AT 84.4 DEG.F
= 7.37 KO/HR AT 29.1 DEG.C
-- 3.04 SCFM
NITROGEN* 4.55 LB/HR AT 87,8 DE6.F
* 2.06 KG/HR AT 31.0 DEG.C
= 0.97 SCFM
PURGE N2 -- 5.82 LB/HR ( 1.24 SCFM)
= 2.64 KG/HR
STEAM/COAL * 1.81 LB STEAM/LB COAL
-------
Table 6 Continued
RUN 60-28 8/14/79 12:30-17130
CONTROL VARIABLES
OUTPUT VARIABLES
TEMPERATURE - 1830,0 DE8.F
N2/02 MOLAR FEED RATIO = 0,32
STEAM PARTIAL PRESSURE = 98,69 PSI
BED HEIGHT - 3,17 FT
SOLID SPACE TIME = 27,3 HIM
6AS SPACE TIME = 2,71 S
PRESSURE DROP OVER 20 IN,
PCS 6AS FUN RATE
CYCLONE 8AS FLOM RATE
SOLID HOLDUP
= 9,0 IN.H20 ( 0,325 PSI)
= 2.2 KPA
= 2.64 LB-MOLE/HR (15.79 SCFM)
= 2,42 LB-MQLE/HR
-------
Table 6 Continued
RUN 60-28 8/H/79 12530-17:30
ELEMENTAL MATERIAL BALANCES ! FLOWS IN LB/HR
HASS C H 0 N S
COAL 38.2
BASES 86,2
TOTAL INPUT 124,4
CHAR 16,0
DUST 1,6
GASES 103,7
UASTEUATER 0,0
TOTAL OUTPUT 121,3
Z RECOVERY 97,51
FEED AND EFFLUENT TEMPERATURES
COAL IN * 200,0 DEG.F
GASES IN = 990.0 DEG.F
CHAR OUT * 1830.0 DE6.F
GASES OUT * 1716,0 DEG.F
31,04 0.17
0,00 6,67
31.04 6.84
11.63 0.03
0.99 0.00
16.16 6.69
0.00 0.00
28,78 6,72
0.70 0,40
69.17 10,37
69.87 10.76
0,25 0,01
0,01 0,02
69,37 10.84
0.00 0,00
69,63 10.87
92.7Z 98,32 99,71 101,02
1
!
1CI6Y IN *
TtRBY OUT =
CAT LOSS =
t HEAT LOSS *
1.002
0,000
1.002
0,256
0,023
0,584
0,000
0,863
86,22
ENERGY BALANCE
:«M!:ffl
8.50EW3 BTU/HR ( 8.96E+03
2,82
VSK
KJ/HR)
TRAP HATER ANALYSIS
SPECIES C
-------
Table 7
mwmwmmwiwuwwiwmm
I NCSU DEPARTMENT OF CHEMICAL ENGINEERING I
t FLUIDIZED BED COAL GASIFICATION REACTOR *
tmmmmmmmmmmmtwmt*
RUN GO-28 8/14/79 12J30-17J30
COAL FEED Mtt
38.2 LB/HR GAS OUTPUT t t
\ • ,._.______\* * ^«
0.8133 C
•mi
0.0104 N
0.0262 S t
0.1273 ASH j
i
:
i
!
!
CHAR REMOVAL
16,0 LB/HR
0.7263 C
0.0016 H
O.*0160 S
0.2398 ASH
• » T *
> . 1 *
i i "•
v i
wmsttmtro
"W?
PROFILE
55" 1716 F
45" 1766 F
35" 1798 F
25" 1805 F
i 10" 1829 F
»
i 5" 1859 F
i
MttttMMMMM
1170 F t t
71H20 t t
CYCLONE
:-
I SCRUB
WATER
32.0 6PH
6ASIFIER
T(AV) « 1830 F
P(AV) = 104.0 PSIG
BED LEVEL > 38.0 IN
SOLID HOLDUP = 17.3 U
C CONVERSION * 52.6Z
»
»M»XM*MM**»
1 t GAS FEED
----'» 228 F
SOUR GAS
( 15,8 SCFM
i ! 84.9 F
V i 98.2 PSIG
UlttttttHllt
19. 71 CO
33.2ZH2
2.4ZCH4
28.71 C02
14.7ZM2
T« 90 F 0.5ZH20
V « 189 GALt 6692 PWj
I 250 ml
i'
< 1;
D^C TAMV
rvo IfMK
59
-------
Bed Temperature 10 Inch
Bed Temperature 35 Inch
Reactor Pressure
Product Gae Flow
Bed Delta P
(Sample Times
.
1800
6
9OO
1000 11OO
1200 1300 1400 150O
Time
GASIFIER • PCS RUN GO-28
Figure 16
160O 17OO
u.
o
1600 2
*•
a
k.
a
1400 |
•1200
•10
9
8
a.
a
-------
and gas analyses are accurate. The closure for sulfur is not as good but
is expected to improve when sulfur in the waste water is properly account-
ed for.
A kinetic model of the gasifier, based on kinetics developed by
Johnson (3), was programmed for the data acquisition system computer. The
model takes as input the reactor average bed temperature and pressure, feed
rates of coal, steam, oxygen, nitrogen, and purge nitrogen, solids holdup,
ultimate analysis of the feed coke and spent char, the relative reactivity
of the coke and the C0/C02 distribution coefficient.
The model output, consisting of one page, echos the reactor specifica-
tions and feed rates and shows the comparison of the model and experimental
values for dry make gas flow rate, char removal rate, carbon conversion and
gas composition (wet basis). Table 8 shows the results of the model predic-
tions for GO-28. For this run, the prediction is very godd.
In general, for those runs with good mass balances and good fluidized
beds the model compares well with experimental results.
A full report on the results of the first set of planned gasifier runs
is to be issued soon.
ACID GAS REMOVAL SYSTEM
As was indicated, the gas produced in the gasifier during GO-28 was
fed to the AGRS where it was contacted with refrigerated methanol to remove
C02 and sulfur gases. The operating conditions for this run are represented
schematically in Figure 17. It should be mentioned that in both the stripp-
ing and absorption columns 21.3 feet of 1/4-inch ceramic Intalox saddles
were used as the packing material.
61
-------
Table 8
tmmmmmmmmtmm
* t
I WELL-MIXED CHAR GASIFICATION I
* «
t HODEL RESULTS t
* *
mmmmmmtmtwttm*
60-28 8-14-7? 12J30-17J30
REACTOR SPECIFICATIONS
BED PRESSURE(ATH) 104.00
BED TEHPERATURE(F) 1830.00
SOLIDS HOLWP(LB) 17.30
BED HEIGHTUN) 38.00
BED DIAMETERUN) 6.00
FEEDRATES(LB/HR)
INLET CHAR 38,16
STEAM 59,59
OXYGEN 16,26
NITROGEN 4,55
HYDROGEN 0,00
PURGE N2 5,82
MODEL PARAMETERS
PRETREAT TEMP(F) 2000.00
CHAR REACTIVITY 0.4030
COMBUSTION EXTENT 0.8030
FEED CHAR ANALYSIS(WT PERCENT)
CARBON
HYDROGEN
OXYGEN
NITROGEN
SULFUR
ASH
81,30
0,40
1,80
1,00
2,60
12,70
»tt RESULTS ttt
DRY 6AS FLOW RATE (SCFH)
STEAM CONVERSION
CARBON CONVERSION
COMBUSTION
GASIFICATION
TOTAL
ASH CONTENT OF CHAR
CHAR REMOVAL RATE (LI/HR)
MODEL EXPERIMENTAL
16,24 15,79
0.335 0.311
0.24S
0.333
0.578
25,63
18.04
0.526
24.00
16.00
GAS COMPOSITION (MOLE PERCENT)
MODEL EXPERIMENTAL
CO
H2
CH4
C02
H2
H2S
COS
H20
11,39
17,00
2.94
16.08
7.62
0.21
0.00
44.76
10,64
17.77
1.30
15,37
7,86
0.36
0.01
46.68
62
-------
RUN NUMBER A-N-13
INTEGRATED RUN
DATE 8/14/1979
COLUMN TEMPERATURE PROFILES t MASS BALANCES
ABSORBER
P=497,40 PSI6
.—> SUEET
GAS
mm
FLASH TANK
P»144,83 PSI6
FLASH
6AS
STRIPPER
P* 9,88 PSI6
,— > ACID
\ 6AS
I
un
I
4
t
tttttttttt
.W=»
(-33,64 F)
. 11 IN H20
l*Ow •" *•*"
^€ttB fiJlfi
ilTTO SOT ->
( O3»
t
t
t
t
t
-27,26 Ft
t
-27.2? Ft
f
t
f
-20.6? Ft
t
-20,88 Ft
t
t
-18.48 Ft
t
-13,?3 Ft
t
t
t
t
22.?1 Ft
*»i>_r
"
t
s
tttttttttt
1
\
\
j ttttttmt
i
t
j
t
t 32,36 F
t
, .---... -.----^t
i !
t t
t
f
t
t
lit'
i
s
f
i
i
I •...._...*.
"»"««•—""• •"•—
- 0.57 GPN -t t
(53,37 F) t t
t t
t t
t 28,79 Ft
t t
t 27,72 Ft
t t
t t DP* 0.37 IN H20
! ;
t 30,65 Ft
t t
t 34.32 Ft
t t
t t
t 35,03 F!
> t t
1 t 35,48 Ft
itttti i v
t t
STRIPP IMG N2- 1.0? SCFH ~>J t
(75,00 F) t t
t 52,17 Ft
t t-TO MSOWOt->
t t
t t
tttttttttt
Figure 17
63
-------
Several process temperatures are depicted in Figure 18. Normal operat-
ing procedure calls for the system to be cooled down using refrigerated me-
thanol with only N2 as the feed gas to the absorber. When gasifier opera-
tion has stabilized, the product gas is then fed to the absorber. During
AMI-13, system integration took place at 11:30 and can be seen in the tem-
perature rise of the solvent in the absorber bottoms reservoir. This, of
course, is attributed to the heat of solution of the acid gases in the me-
thanol. After some lag, the desorption endotherm in the stripper is also
evident. At 17:30, changes seen in the column temperature profiles are the
result of the beginning of system shut down and after all samples were taken
The gas and liquid samples were taken at 16:30 and 17:30. Averages of
all process parameters and analyses are used in the mass balance calcula-
tions. It should benoted that while the absorber and flash tank temperature
are fairly constant over this period, there is some change in the stripper
temperatures. These temperature variations stem from the amount of solvent
inventory in the system at a given time, but, since most of the solvent hold
up is in the bottoms reservoir of the stripper where the solvent is essenti-
ally clean methanol, it is felt that this has a minimal effect on system oper-
ation. This, in fact, has been substantiated by several runs using a CO -N
methanol system. Furthermore, the slow temperature decline in the stripper
packing results from the exchange of heat between the solvent having the strip-
per bottom and the solvent being fed to the stripper from the flash tank.
(Refer to Figure 10, the Lean/Rich Exchange). The packing section temperature
profile, therefore, will not line out until the temperature of the solvent
leaving the stripper reaches a steady state.
64
-------
AGRS RUN AMI-13
W1
-40
Stripper Bottom Outlet
Lower Packing Section, Stripper
Absorber Bottom Outlet
Lower Packing Section Absorber
Upper Packing Section Absorber
Solvent Feed Temperature Absorber
9OO 10OO 11OO 120O
130O 14OO 150O 1600 17OO 18OO
Time
-------
The mass balance calculations for AMI-13 are presented in Table 9.
Mass balance closure was adjusted to compensate for several problems that
were found at the time of the run. A leak of approximately 1 SCFM was
found in the relief system in the absorber, and the sweet gas flow was ad-
justed to compensate for this loss. In addition, process controller tuning
caused fairly wide oscillations in acid gas flow. The methanol flow rate
to the stripper was found to be the reason for this problem. Because this
steam contains H2S, C02,and COS, the concentration of the gases in the acid
gas will vary with the inlet solvent flow to the stripper. To account for
this, the C0?, H2S, and COS balances were adjusted. The problems with COS
balance closure can be attributed to analytical inaccuracies. The problem
has since been corrected.
Also presented in Table 9 are calculated solvent stream compositions.
Although the streams were sampled and analyzed, there are still problems in
these areas which are now being investigated. The calculated compositions
are checked using the vapor-liquid equilibrium data generated in the VLE
laboratory, assuming the flash tank is an adiabatid flashing operation.
In general, the AGRS has operated extremely well. Usually, before any
adjustments are made in the mass balance calculations, better than 92% clo-
sure is found. Current emphasis is on developing a mathematical model for
the C02-N2-methanol systems with plans to extend this calculation for the
multicomponent system. Also, since less than a tenth of the available mass
transfer area is required for the bulk of the C02 and H2S removal in the ab-
sorber, additional temperature sensors are being installed to follow mass
transfer rates by monitoring the absorption exotherm. It is hoped that this,
1n addition to samples taken from the column packing, will provide the
66
-------
Table 9
mmtsmmimmtmmttttmmtmt
NCSU DEPARTMENT OF CHEMICAL ENGINEERING
ACID GAS REMOVAL SYSTEM
mitttmtmitmtmtttmsmmtww
RUN NUMBER A-M-13
INTEGRATED RUN
DATE 8/14/1979
STREAM COMPOSITION (VOL Z)
C02
HEOH
H2
CH4
SOUR GAS
29.100
0.000
33.870
20.03
13J-
2.400
SUEET6AS
0.000
0.000
48.990
28.300
19,930
2.780
RASHGAS
48,070
0,000
23,590
15,900
8,720
3,350
STRIPN2
0,000
0,000
0,000
0,000
100,000
0,000
ACID GAS
77.890
0.000
0,000
0.000
19,590
0,490
ABSORBOT
7.374
92,290
0,000
'
t t
FLASHBOT STWPBOT
6.847
92.903
0,000
0.000
0,000
0.075
0.004
99.442
0.000
0.000
O.S21
0.034
CALCULATED
KASS BALANCE (LB-MOLES/HR)
IN
OUT
SOUR GAS STRIP N2
SUEETGAS FLASH6AS ACID GAS
TOTAL IN TOTAL OUT Z RECOVERY
no
m
rns
MEOH
SHtw
M2
&
TOTAL
0,569
0,013
0.001
0.000
0.662
0,392
0,268
0,047
1,955
0.000
0,000
0.000
0,000
0,000
0,000
0,182
0,000
0,182
0.000
0,000
0.000
0,000
0,672
0,388
0,273
0,038
1,372
0,044
0,000
0,000
0,000
0,022
0,015
0,008
0.003
0,092
0,525
0.013
0.001
0.000
0.000
0.000
0,132
0.003
0,674
0.569
0.013
0,001
0.000
0.662
0.392
0.451
0.047
2,134
0.569
0,013
0.001
0.000
0.694
0.403
0.413
0.045
2.137
99.953
99.961
123.295
O.OM
104.742
102.846
91.723
94.847
100.129
(LB-MOLES/HR)
METHANOL-FREE BASIS
TOTAL METNANOL LOSS* 0.000 LB-MOLES/HR = 0,000 GALLONS/HI
67
-------
necessary information to characterize the solvent system used.
REFERENCES
1. American Society for Testing and Materials, 1976 Annual Book of ASTM
Standards
2. American Public Health Association, American Water Association, and
Water Pollution Control. Federation, Standard Methods for the Exami-
nation of Water and Wastewater, 14th ed., Washington, D. C., Ameri-
can Public Health Assoc., 1976.
3. Johnson, J. L., "Kinetics of Bituminous Coal Char Gasification,
with Gases Containing Steam and Hydrogen," Adv. Chem. Ser., No.
131, 1974.
4. Ferrell, J. K., R. W. Rousseau, and D. G. Bass, "The Solubility
of Acid Gases in Methanol," EPA-600/7-79-097, April, 1979.
5. Agreda, V. H., R. M. Felder, and J. K. Ferrell, "Devolatilization
Kinetics and Elemental Release in the Pyrolysis of Pulverized
Coal," EPA-600/7-79-241, November, 1979.
68
-------
APPENDICES
69
-------
Appendix I
GASIFIER - PCS PRESSURE TEST
The pressure test should be made the day before each gasifier
run to determine the leak rate for use in the material balance cal-
culations and to assure that the system has no major gas leaks.
A leak rate of less than 0.80 SCFM has proven to be satisfac-
tory.
1. After the vessels are sealed set PIC-310 in auto at 100.0 psig
2. Open AOV-116 and set FIC-116 (N2) at 12.0 SCFM
3. Open AOV-101 and set all purges at a low value (~10)
4. Check that the valve to the on-line sample port SX-1 is closed
5. When gasifier reaches about 75 psig manually check all fittings (with
snoop) that have been opened since the last run
6. Open the valve to the cyclone sample train and set a flow of about 4
at the rotameter. Check all fittings (especially the seal around the
filter housing) for leaks. Close inlet valve to close off cyclone
sample train.
7. Continue pressurization until reactor is at 100 psig
8. Close all purge N2 valves and close AOV-101
9. Start Data Acquisition System. Run (300,2) PTEST
10. Put FIC-116 in loop manual and close the control valve; close AOV-116
11. Put PIC-310 in loop manual and close the control valve
12. Let the pressure decay for at least 30 min.
13. Turn off data acquisition system; Run Stop .
70
-------
14. Calculate the pressure decay
A. Choose two times about 10 m1n. apart (start about 5 itrin. after start
of pressure decay)
B. Substract pressure readings (channel 25) and divide by time span
C. This gives psi pressure drop/m1n (AP)
15, Calculate the system volume from following equation
V (ft3) • 120 9 - * Coke lg ^opper - PCS tank level + 16 7 Q7
HO . <- 12
16. Calculate the leak rate from the following equation:
Leak rate (SCFM) = x 359
71
-------
NUCLEAR LEVEL GAUGE CALIBRATION
LT-101, REACTOR BED LEVEL INDICATOR
The Texas Nuclear density gauge is to be calibrated so that the recorder
indicates 10% when the reactor is empty, and 90% when a 1/2-inch steel plate
is inserted in front of the source. The radiation beam is about two inches
in diameter, and the recorder goes from 10% to 90% as the top of the coal
bed passes the beam.
Calibrate the level gauge while the reactor is empty. Open the shutter.
1. Turn on the control panel switch and allow the detector to warm up for
24 hours, if not already on.
2. Connect a chart recorder to the gauge output in order to determine that
an indication has stabilized.
3. Set the meter and recorder at 10% with the "baseline position" control.
4. Hang the 1/2-inch steel plate between the source and the reactor vessel.
Wait about 5 minutes between steps.
5. Adjust the "density calibration" control to make the output read 90%.
6. Remove the steel plate. If the recorder does not indicate 10%, repeat
steps 3 through 6.
7. Close the radiation source shutter. The recorder will go off up-scale.
72
-------
ON-LINE EQUIPMENT SET-UP
Mom' tor
I Remove cell holder from mount
2. Check that range is on high
3 Adjust to "cal" point with span adjustment
M On lower right hand side of SX-1 cabinet hook-up vent line
e Open V-611 on panel
k Open "sample" valve on SX-1 02 meter
1 f Adjust flow to approx. 1 SCFH
a When reading is less than 5% on 0-25% scale put range on MED
o*
CO & COo Analyzers
- Open main valve on CO, C02 calibration tank
z Set V-651 on N£
Adjust "zero" on both meters
- Set V-651 on C0/C02
* Adjust gain on both meters to calibration gas concentration
y*
* Repeat 2 to 5 until zero and range both correct
V'
- Set V-651 on N9; close main valve on gas cylinder
7- c
a Open SX-1 (at control panel)
8»
g Close V-617
Should observe approximately 26-28 psi pressure
10»
,1 If not open valve on SX-1 panel at filter outlet
1 1 •
Set all cabinet purges to 10 SCFH
„„ Turn all dryers on
|3-
Set-up recorders in control room
!*•
If you wish to look at port other than SX-1
15 •
A. Close V-611 (02 monitor stays at SX-1)
73
-------
B. Turn on SX- port that is desired at control panel
C. Open appropriate valve on panel (in plant)
D. Change as desired
E. If stripper exit is desired turn pump on first
Cyclone Sample Train
1. Turn on heat tracing of sample train line
2. Turn on cooling water to sample train condenser
3. After startup is nearly complete set sample train floor at a rota-
meter reading of 8.
74
-------
SHUT-DOWN FOR ON-LINE EQUIPMENT
CO & C02 analyzers
None required
02 monitor
1. Wait until all AOV's on gasifier are in manual
2. Turn off SX-1 at control panel
3. Open V-617; set range on high
4. Open V-611 (may already be open)
5. Set V-651 on N2 (may already be there)
6. Turn cabinet purges off
7. Turn dryers off
8. Close sample valve on SX-1 02 monitor
9. Hook-up C02 cylinder to "span" fitting
10. Open "span" valve
11. Set C02 pressure at approximately 10 psig
12. Let flow for approximately 10 minutes at 2 SCFH
13. Remove vent line
14. Install plugs and turn "span" valve off at the same time
15. Remove C02 cylinder
Cyc1 one Sample Tra i n
Allow sample train to run during shut down for a sufficient time to
purge test meter with nitrogen.
1. Turn off sample train flow
2. Turn off cooling water
3. Turn off heat tracing
4. Drain remaining water from condensate tank
75
-------
GASIFIER OPERATION PROCEDURE
Day before Run
1. Complete pre start-up checklist (See appendix)
2. Turn on nuclear level gauge.
3. Run pressure test
Day of Run
1. Turn exhaust fans on
2. Light flare
3. Check status of on-line equipment
4. Reset alarm system at alarm panel
5. Set AOV's according to following table
Setting
Auto
Auto
Auto
Closed
Auto
Auto
Auto
Auto
Auto
6. Check that PIC-310 is in auto at 99.5 psig
7. Set purges at a low value (approximately 10 SCFH)
8. Set FIC-116 at 12 SCFM; turn H-13 on 9 1000°F
9. Check that steam is on by-pass; drain condensate from steam line and
superheater by opening V-321 and V-327
AOV
110
111
ITS
116
117
Setting
Auto
Closed
Auto
Auto
Auto
AOV
101
213
215
241
254
270
294
296
297
76
-------
10. Set FIC-115 (Stm) at 40 #/hr; turn H-14 on (? 1000°F
11. When PT-310 is at 99.5 psig, turn venturi scrubber pump on
12. Reset N2 purges
Feed Hopper 10 SCFH
Feed Screw 100 SCFH
Reactor Shell 40 SCFH
Receiver 0 SCFH
13. Reset FIC-116 to 13.5 SCFM for remainder of heatup
14. When TT-201 reaches 400°F start coke feed (see coke feed Instructions)
15. Reset FIC-115 (STM) to 15 #/hr
16. When TT-201 reaches 650°F start oxygen: reduce N« to 12.5 SCFM, set
02 at 0.10 SCFM
17. If TT-201 does not respond within about 1 min., turn the oxygen off
and let the bed heat to about 675°F before trying ignition again.
18. Bring TT-201 to 1400°F very slowly (having the bed temperature under
control at this point tends to reduce problems during the remainder
of the start-up)
19. When TT-201 reaches 1400°F, increase oxygen by 0.50 and take steam
off bypass. (Note: It takes approximately 7 minutes to take steam
off bypass — allow plenty of time)
20. Bring TT-201 from 1400°F to 1800°F (or desired temperature) by in-
creasing oxygen; during this time increase stm from 15 l/hr to the
final value; decrease N2 so as to maintain a space velocity of about I.Q
21. Set FIC-114 (stm) and FIC-116 (N2) to their final values
22. Reset N2 purges
77
-------
Feed Hopper 0
Feed Screw 100 SCFH
Reactor Shell 40 SCFH
Receiver 0
23. When bed temperature is stable at desired temperature, set 0? on
cascade. While Og is on cascade, watch the bed temperature profile
at all times. If the next higher thermocouple becomes hotter than
the control thermocouple, remove 02 from cascade control and lower
the Op output by approximately 0.05. If this does not line out the
temperature profile, reduce Og by 0.05 again. Once the temperature
profile is correct, increase 02 so as to bring the bed to the de-
sired temperature. Return 02 to cascade.
24. During start-up if the bed delta-P rises very high (>30) a sudden
large (approximately 10 SCFM) increase in nitrogen input may loosen
the bed and lower the AP.
78
-------
COKE FEED INSTRUCTIONS
1. When TT-201 (01 on recorder) reaches 400°F start feed screw at 40 rpm (no
removal)
2. Stop feed when 03 (TT-203, 25" bed) responds (approximately 2500 counts);
Turn removal screw on and remove about 10 counts, then turn off
3. Do not feed or remove during remainder of heat-up
4. When 02 is started set feed at 20 rpm and set removal at 20 rpm (this will
very slowly build the bed; maintain these rates as steady as possible so as
to aid the chief operator)
5. When the bed temperatures are near the final values and the bed AP is near
normal slowly increase the feed RPM to the steady state value; maintain the
removal rate at 20 rpm (this will build the bed)
6. When the bed level is established set the removal rate so as to maintain the
bed at 48-50% of scale, on recorder.
7. If during start-up the bed lifts (indicated by TT-201 (or 01 on recorder)
falling rapidly) turn feed screw off and set removal rate at about 10 rpm
8. At start of shutdown turn feed screw off and record both total feed counts
and removal counts on Gasifier Report Sheet. After feed screw is shut off
set removal at approximately 60-70 rpm.
79
-------
GASIFIER SHUT-DOWN
1. Check that the propane to the flare is on
2. Turn off H-13 and H-14
3. Stop feed screw; record removal counts
4. Bring down CL flow while increasing Np to maintain UQ
5. Bring down Stm flow while increasing N«; when steam is at approximately 20 #/hr
put on bypass
6. Reset all AOV's
110 closed 101 open
111 closed 213 closed
115 closed 215 closed
116 open 241 closed
117 closed 254 closed
270 open
294 closed
296 open
297 closed
7. Set N? at approximately 10 SCFM and maintain until TT-201 is approximately
1200°F
8. Turn off scrubber pump and N2
9. Close AOV-116 and AOV-270
10. Put PIC-310 in loop manual open valve to approximately 8%
11. Close AOV-101 and close purge N2 valves; check shut-down of on-line instru-
ments; turn off cyclone sample train; close shutter to nuclear level gauge;
close main N~ valve
80
-------
AGRS OPERATION PROCEDURE
Day before Run
•j. Turn dehydrators on; check N2 purge flow (.5 SCFH); check that refrigerator
oil heaters are on.
2. Complete pre-start-up checklist (see appendix)
3. For syngas runs check for sufficient gas cylinder supply
Day of Run
3. Open refrigerator compressor isolation valves (3)
4. Reset alarm system at alarm panel
5. Set AOV's
AOV Setting
-Syngas auto
"integ. closed
333 auto
341 auto
360 closed
381 closed
393 auto
395 closed
Settinq
auto
closed
closed
auto
auto
g. For a Syngas run check that PIC-310 is in auto and set at 100 psig
7. For a Syngas run set syngas N2 at approximately 10 SCFM and set FIC-315 at
approximately 6 SCFM; set PCV-345 (absorber) at 95 psig; open CCL tank valves
81
AQV
309
322
340
356
397
399
Setting
Auto
Auto
Auto
Auto
Auto
Auto
AOV
131
141
151
140
150
AOV
310
330
345
351
352
370
Setting
auto
auto
auto
auto
auto
auto
-------
8. Set PIC-370 (stripper) in auto at 10 psig; set stripping N2 at DV = 1
9. Using process N2 (by opening V-248) set flash tank pressure to 30 psig using
PlC-353
10. When absorber is at 95 psig reset FIC-315 to 4 SCFM
11. Check that LIC-341 and LIC-351 are in auto
12. When all pressures have stabilized turn on P-35 (solvent circulation pump)
DO NOT set over 50%;when positive indication of solvent flow is seen (PT-
354 pulsing) turn refrigerator system on and set TIC-349 at -35°F; if P-35
is vapor locked close V-549 and momentarily open V-554. Immediately open
v-549; repeat if necessary. CAUTION: Some solvent will be discharged down drain.
13. After indication of cooling is noted (TT-349 falling) begin to pressurize
the absorber to 480 psig as follows;
A. Set FIC-121 (N2) at full open (15 psig output)
B. Turn sourgas compressor (CP-31) on and close V-1006
C. Reset PIC-345 (absorber) to 480 psig
D. Reset FIC-315 to approximately 6 SCFM
E. Reset syngas N~ flow such that PIC-310 control valve is approximately
10-15% open
14. When absorber reaches about 200 psig reset PIC-353(flash tank) to 100 psig
15. When absorber bottoms temperature reaches 40°F turn off process N2 to flash
tank (close V-248) and set PIC-353 to desire pressure
16. When temperatures reach the desired values initiate complete synqas flow
using AGRS conditions report as a guide
82
-------
INTEGRATED RUN PROCEDURE
Gasifier - use normal start-up
AGRS
1. Set PCV-308 at 100 psig
2. Open V-240 to supply start-up nitrogen to AGRS
3. Pressurize AGRS as normal (see AGRS operating procedure) but with FIC-315
less than 7 SCFM
4. Integration procedure
A. Open V-552 (Gasifier-AGRS isolation valve)
B. Set FIC-315 at approximately 1.0 SCFM
C. Set PCV-308 such that PT-313 is approximately .6 psi lower than PT-310
D. Place PIC-310 in loop manual
E. Open AOV-305 (set in auto)
F. Close V-240 (process N2 supply)
G. Remove PIC-310 from loop manual
H. Increase FIC-315 slowly
5. Increase FIC-315 to desired value but not so high as to decrease PIC-310
valve position to less than 10%. Continue to monitor valve position of
PIC-310 and if position becomes less than 4%, reduce setpoint of FIC-315
Note: To conserve make-gas flow after integration open SX-2 and route
gas to SX-1 02 monitor, then turn off SX-1 sample port. This will con-
serve approximately 0.7 SCFM of gas.
83
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GASIFIER - AGRS SEPARATION PROCEDURE
1. If the oxygen monitoring point has been moved to SX-2 move it back to SX-1
2. Slowly lower FIC-315 to 1.0 SCFM (observe PCV-310 for erratic behavior)
3. Close AOV-305 and open V-240 at the same time
4. Set FIC-315 at 5 SCFM to purge system; increase stripping N2 to DV = 3
5. Close V-552 (gasifier - AGRS isolation)
84
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AGRS SHUT-DOWN
1. If run was a syngas run turn off flows of H2S, mixed gas and C02; adjust
N2 flow to compensate
2. Set FIC-315 to 5 SCFM to purge system; set stripping N2 DV = 3; reduce
flash tank pressure to 100 psig and open V-248 (process N2 supply) to
set a flow of approximately 1.0 SCFM
3. Turn off refrigeration unit and valve off compressor
4. After all acid gases have been vented from the system turn solvent cir-
culation pump P-35 off and allow solvent to drain from packing. After
approximately 2 minutes place LIC-341 and LIC-351 in loop manual and close
the valves
5. Close FCV-315 (in loop manual) and turn off CP-31 (sour gas compressor)
6. Turn syngas N2 off (if syngas run) or close V-240 (if integrated run)
7. Turn off stripping N2 to stripper; leave all pressure controllers in auto
8. Turn all AOV's to the closed position after manual power is restored.
Audible click can be heard behind panel.
9. Turn all gas cylinders off
10. Turn off dehydrators D-31 (breaker #5)
11. If run was a syngas run and HgS was used open AOV-310 (FIC-315 in loop
manual; closed) and turn on AOV-140 and AOV-150 (purge N2 supply to syn-
gas box) leave these purges on for 5 min.; close AOV's 310, 140, 150
12. Close main N2 valve
85
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Appendix II
AGRS - Manual Valve Settings
I. Gas Lines
Valve
V-237
V-121
V-122
V-301
V-303
V-305
V-307
V-302
V-304
V-306
V-361
V-369
V-546
V-552
V-240
V-241
V-368
V-331
V-264
V-1006
V-1010
V-1009
V-1013
V-1005
V-l014b
Position
open
open
open
closed
closed
closed
closed
closed
closed
closed
open
open
closed
open
closed
open
closed
closed
open
open
closed
closed
closed
open
closed
Location Level
N2 supply to syngas First floor
N2 inlet to manifold
N2 inlet to manifold
CCL inlet to manifold
H2S inlet to manifold
Mixed gas inlet to manifold
Manifold drain
Low point drain
Low point drain
Low point drain
Manifold exit
Syngas supply to dehydrators
(closed for Integrated run)
Gasifier - AGRS isolation valve
(open for integrated run)
Gasifier - AGRS isolation valve
(closed for integrated run)
Process N2 supply at dehydrators
Purge N2 to dehydrators
dehydrator bypass valve
F-33 drain
Compressor isolation valve
Manual spill back valve
Suction bottle drain
Discharge bottle drain
Knockout bottle drain
E-31 exit valve
Gas chiller by-pass
86
-------
Manual Valve Settings - Cont.
Valve
V-1015
V-1023
V-1024
V-1025
V-1017
V-444
V-449
V-182
V-158
V-159
V-160
V-161
V-162
V-163
V-164
V-165
V-448
V-248
V-246
V-452
V-1026
V-1027
V-223
V-225
V-1028
I. Gas Lines
Position
open
open
closed
closed
open
closed
open
closed
closed
closed
closed
closed
closed
closed
closed
closed
open
closed
open
closed
closed
closed
closed
closed
closed
Location Level
Gas chiller exit First floor
Spill back access valve
Surge bottle drain
Compressor exit gas sampling valve
Purge ^ to absorber bottom
Process N2 to absorber bottom
Purge N2 to stripper bottom
Steam to reboiler
Steam exit from reboiler
Purge N2 to flash tank Second floor
Process N2 to flash tank
Gas exit from flash tank
Manual pressure release for flash tank
Flash tank gas sample valve
Absorber gas sample valve Third floor
Manual pressure release for absorber
Manual pressure release for stripper
Stripper gas sampling valve
87
-------
Manual Valve Settings - Cont.
Valve
V-587
V-589
V-590
V-548
V-554
V-549
V-363
V-1003
V-1035
V-1004
V-1016
V-1007
V-335
V-1001
V-1002
V-106
V-1012
v-ion
V-1040
V-1041
V-512
V-513
V-519
V-561
V-505
V-506
II. MeOH
Position
open
closed
closed
closed
closed
open
closed
open
closed
closed
closed
closed
open
closed
closed
open
open
closed
closed
open
closed
open
open
open
closed
closed
and Water Lines for MeOH system without trim heater
Location Level
MeOH supply to P-35 First floor
Start-up tank isolation valve'
MeOH supply to start-up pump
Drain line at P-35 exit
Drain line at P-35 exit
P-35 exit
Start up pump exit
MeOH to gas chiller
MeOH drain and vent line
MeOH injection valve
MeOH drain @ rupture plate
MeOH drain and vent line
MeOH restriction valve
Block valve
Block valve
Cooling water supply to E-31
Cooling water discharge from E-31
E-31 shell side vent
Cooling water bypass for refrig.
Cooling water exit from refrig
MeOH bypass at refrig
MeOH feed to refrig
MeOH feed to refrig
MeOH exit from refrig at E-36 Second floor
At E-36
88
-------
Manual Valve Settings - Cent.
Valve
V-507
V-508
V-509
V-510
V-511
V-484
V-485
V-1018
V-481
V-482
V-154
V-1019
v-no
V-572
V-573
V-555
V-526
V-334
V-525
V-527
V-536
V-528
V-550
V-529
V-450
V-533
II. MeOH and
Position
closed
closed
closed
closed
closed
closed
closed
closed
closed
closed
closed
closed
closed
open
only one
open
only one
open
only one
open
closed
closed
closed
closed
closed
closed
closed
open
closed
Water Lines for MeOH system without
Location
Water supply at E-36
Top feed to absorber
Middle feed to absorber
Bottom feed to absorber
MeOH bypass at F-31
MeOH sample tap at F-31
F-31 isolation
F-31 isolation
F-31 drain
F-31 drain
Absorber bottom drain
Flash tank by pass
Manual absorber level control
Flash tank drain
trim heater
Level
Third Floor
Second Floor
First floor
Second floor
89
-------
Manual Valve Settings - Cont.
Valve
V-530
V-333
V-557
V-558
V-559
V-531
V-534
V-535
V-537
V-538
V-539
V-556
V-560
V-1024
V-593
V-595
V-594
V-593
V-520
V-330
V-451
V-112
V-157
V-156
II. MeOH
Position
open
closed
open
closed
closed
open
closed
closed
closed
closed
closed
closed
closed
open
closed
open
closed
closed
closed
closed
open
closed
closed
closed
and Water Lines for MeOH system without trim heater
Location Level
Flash tank exit Second floor
MeOH sample tap at flash tank exit
E-37 bypass First floor
E-37 bypass
E-37 bypass
Feed to stripper
At E-37
Reboiler drain
Reboiler drain
Reboiler exit
E-37 bypass
E-37 bypass
E-37 exit
E-37 exit
Chemical addition pump
MeOH sample tap at reboiler exit
Manual level control for flash tank at stripper top
Cooling water for E-38
Cooling water for E-38
Cooling water for E-38
90
-------
MODIFICATION LIST FOR AGRS VALVING LIST
UJLJIJ5L kean/ft J PJl Jfeftt-E* change r
Liquid Side Valves
V-595 closed
V-593 open
V-594 open
V-557 closed
V-558 open
V-559 open
Integrated Run
Gas Side Valves
V-369 closed syngas supply to dehydrators
V-546 open Gasifier AGRS isolation valve
V-552 closed Gasifier AGRS isolation valve
-------
COAL GASIFICATION PLANT START UP CHECKLIST
Run No. Date
Gasifier: Air 00 Syngas
Integrated
Item
1. Nitrogen tank level
2. Nitrogen tank pressure
3. a. Propane tank level
b. Propane regulator pressure
4. Main N2 supply valve
5. Main propane supply valve
6. Main steam supply valve
7. Main water supply valve
8. Oxygen mainfold pressure
9. Main 208 V breaker
10. Main 440/480 V breaker
11. Purge N2 pressure PCV-123
12. Process N2 pressure PI-121
13. Scrubber circulation pump
Oil level and status
Scrubber drain pump status
Feed screw motor
Oil level and status
Removal screw motor
Oil level and status
Air compressor
Oil level, belt tension, status
Setting or Reading Initials Date
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
Scrubber tank manway
PCS Tank Cleaned
Steam on by-pass
02 regulator PCV-101 at 200 psi
02 regulator PCV-110 at 135 psi
Nuclear level gauge
Feed hopper charged
Feed hopper vent closed
Feed coke sampled
PCS tank level
PCS valving configuration
92
-------
Item Setting or Reading Initials Date
29. V-324 closed
V-566A Open
V-566B Closed
V-501 Closed
V-583 Closed
V-567 Closed
V-564 Closed
V-581 Closed
V-565 Closed
V-546 Open
V-552 Closed
30. Reator pressure test
31. Scrubber pump setting
32. All unnecessary extension cords unpluged
93
-------
ACID GAS REMOVAL SYSTEM START UP CHECKLIST
Run No. Date
Gasifier: Air CL Syngas Integrated_
Item
1. Refrigerator oil reservoir
crankcase heaters on for 24 hrs
2. Check manual valve settings
(See Appendix A)
3. a. Nitrogen tank level
b. Nitrogen tank pressure
4. a. Propane tank level
b. Propane tank pressure
5. Main N2 supply valve
6. Main propane supply valve
7. Main water supply valve
8. Purge N2 pressure PCV 123
9. Process N2 pressure PI 122
10. Check availability of gas cylinders
(C02, H2S, etc.) for syngas run
11. Solvent circulation pump
oil level and status
12. Startup pump status
13. Sour gas Compressor
oil level, belt tension, status
14. Syngas tank pressures
a) C02 tank pressure
b) H2S tank pressure
c) Mixed Gas tank pressure
15. Syngas supply pressure
a) C02 supply pressure @ 250 psi
b) H2S supply pressure @ 125 psi
c) Mixed gas supply pressure @ 135j3si
Setting or Reading^ Initials Date
94
-------
Item
16. Dehydrators in line (V-368) closed
17. Purge N2 to dehydrators set at .5 SCFM
18. Instrument air to dehydrators on
19. Drain suction, discharge and post-
compressor surge bottles
20. Vent shell side of E-31 on
sourgas compressor
Setting or Reading Initials
21
Foxboro controllers settings
No. 1 set at 568 psig
No. 2 set at 50 psig
22 Manual spill back valve (V-1006) open
--a Valves on level sensing AP cell open
{.•j •
•)n Level control valve for flash tank
selected (back of rack 7)
25. Water supply to refrigerator open
26. Vent shell side of condenser
on refrigerator
27. Refrigerant level in reservoir
28. Instrument air to refrigerator PI-J50
set at 40 psig
29. Refrigerator crankcase oil level
30. Alarms for refrigerator (any on)
95
-------
POSITION
UP:
CENTER:
DOWN:
Appendix III
GASIFIER - PCS - AGRS ALARMS
ALARM BUS CONTROL SWITCHES
ACTION
Alarm, 2 Min. Delay, Shutdown
Alarm only
Immediate Shutdown (Oxygen, Air, and Steam off;
Nitrogen full on. In the AGRS system, supply
gasses and gas compressor off.)
TAG
FAL/H-114
FAL/H-115
FAL/H-116
TAH-130
TAH-140
PAL/H-114
TAH-132
TAH-142
DPAH/HH-201
PAH-213
DPAH-232
DPAH/L-231
TAH-234
CONDITION
Low/high oxidant feed rate; -10%,+
fail to follow (FTF)
Low/high steam feed; +22%, -10% FTF
Low/high nitrogen feed; +10%, -10% FTF
Oxidant feed temp. > 1350°F
Steam feed temp. > 1557°F
Oxidant supply pres. < 110 or > 180 PSI
H-13 Heater temp > 2000°F
H-14 " " > 2000°F
Reactor differential press. > 25/> 48" Water
Reactor pressure > 110 PSI
Scrubber diff. press > 98" Water
Water injection differential
Pressure < 5 or > 18 PSI
Scrubber exit temperature > 350°F
96
-------
DPAH-291 Filter differential pressure > 30" Water
TAH-293 Sour gas temperature > 350°F
TAH-315 Absorber feed gas temp > 2% over set point
PAH-345 Absorber pressure > 540 PSI
TAL/H-349 Absorber solvent feed -5% FTP
TAL/H-390 Stripper column temperature <-20° or> 240°F
PAH-370 Stripper column pressure > 12.8 PSI
PAL/H-313 Compressor suction pressure <80 or> 120 PSI
PAL/H-315 Compressor discharge pressure < 200 or > 550 PSI
DPAH-315 Dehydrator differential pressure > 48" Water
DPAH-320 Gas chiller differential pressure > 48" Water
TAH-322 Sour gas temperature > 275°F
DPAH-340 Absorber differential pressure > 48" Water
PAL/H-353 Flash tank pressure < 75 or > 500 PSI
PAL/H-354 Solvent pump pressure < 350 or > 550 PSI
TAH-371 Vent temperature > 142°F
DPAH-390 Stripper differential pressure > 48" Water
The set points for the following switch-contact sensors are not available:
PAH-117 Feed gas pressure
LAL/H-252 Scrub water level
PAL-356 Refrigeration suction pressure
PAH-363 Refrigeration discharge pressure
TAH-363 Refrigeration discharge temperature
PAL-364 Refrigeration oil pressure
TAH-317 Compressor pressure
97
-------
LAL/H-342 Absorber level
LAL/H-352 Flash tank level
LAL/H-392 Reboiler level
LAL-394 Reboiler coil level
PAL/H-122 Nitrogen pressure
PAL/H-131 Carbon dioxide supply pressure
PAH-141 Hydrogen sulfide supply pressure
PAH-151 Mixed gas pressure
PAH-160 Manifold pressure
The following alarms cause immediate pressure release and nitrogen purge:
TAH-201 Reactor temperature > 2150°F
PAHH-213 Reactor pressure > 125 psi
PAHH-345 Absorber pressure > 570 psi
OXH-201 PCS oxygen high
OXH-315 AGRS oxygen high
The electric heaters H-13 and H-14, are turned off by alarms TAH-130, TAH-140,
TAH-132, and TAH-142.
9R
-------
Appendix IV
Table 10
FACTORS FOR UNIT CONVERSIONS
Quantity Equivalent Values
Mass
Length
Volume
Force
Pressure
Energy
Power
1 kg « 1000 g = 0.001 metric ton » 2.20462 Ib - 35.27392 oz.
1 lbm = 16 02. = 5 x 10'1* ton = 453.593 g = OT453593 kg
e
1 m = 100 cm = 1000 ran = 106 microns (y) = 1010 angstroms (A)
= 39.37 in. = 3.2808 ft. = 1.0936 yards = 0.0006214 mile
1 ft = 12 in. = 1/3 yd « 0.3048 m = 30.48 cm
1 m3 = 1000 liters = 106 cm3 = 106 ml
» 35.3145 ft3 = 220.83 imperial gallons = 264.17 gallons
= 1056.68 quarts
1 ft3 = 1728 in3 = 7.4805 gallons = 0.028317 m3 = 28.317 liters
= 28.317 cm3
1 N = 1 kg ' m/s2 = 10s dynes = 105 g • cm/s2 = 0.22481 Ib-
1 lbf = 32.174 lbm • ft/s2 = 4.4482 N = 4.4482 x 105 dynesT
1 atm = 1.01325 x 105 N/m2 (Pa) = 1.01325 bars
= 1.01325 x 106 dynes/cm2
= 760 mm Hg 0 0°C (torr) = 10.333 m H90 @ 4°C
= 14.696 lb,/in2 (psi) = 33.9 ft H,0 t 4°C
= 29.921 inTHg @ 0°C £
1 J = 1 N • m = 107 ergs = 107 dyne • cm
= 2.778 x 10-7 kW • hr = 0.23901 cal
= 0.7376 ft-lbf = 9.486 x 10"1* Btu
1 W = 1 J/s = 0.23901 cal/s = 0.7376 ft - lb,/s = 9.486 x 10'1* Btu/s
= 1.341 x 10"3 hp T
99
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/7-80-046a
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Coal Gasification/Gas Cleanup Test Facility:
Volume I. Description and Operation
5. REPORT DATE
March 1980
6. PERFORMING ORGANIZATION CODE
7. AUTHORtS)
J.K. Ferrell, R.M. Felder, R.W.Rousseau,
J.C.McCue, R.M.Kelly, and W.E.Willis
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
North Carolina State University
Department of Chemical Engineering
Raleigh, North Carolina 27650
10. PROGRAM ELEMENT NO.
EHE623A
11. CONTRACT/GRANT NO.
Grant No. R804811
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Task Final; 9/77-12/78
14. SPONSORING AGENCY CODE
EPA/600/13
is. SUPPLEMENTARY NOTES IERL-RTP project officer is Robert A. McAllister, Mail Drop
61, 919/541-2160.
16. ABSTRACT
The report describes an integrated fluidized-bed coal gasification reactor
and acid gas removal system. The gasifier operates operates at 100 psig at up to
2000 F, and has a coal feed capacity of 50 Ib/hr. The gas cleaning system contains
a cyclone, a venturi scrubber, and an absorber/flash-tank/stripper system for acid
gas removal. The overall objective of the research carried out using the facility is
to characterize completely the gaseous and condensed phase emissions as a function
of plant operating conditions. The report contains a detailed description of the plant
and associated facilities, a summary of operating procedures, and results of a run
for the steam-oxygen gasification of a Western Kentucky No. 11 coal char. By fol-
lowing the outlined operating procedures, the plant can be brought to steady state in
less than 4 hours. At steady state, satisfactory material balance closures were
achieved on total mass and major elements.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATl Field/Group
Pollution
Coal Gasification
Gas Scrubbing
Fluidized Bed Processing
Pollution Control
Stationary Sources
Acid Gases
13B
13H
07A
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (This Report!
Unclassified
21. NO. Of PAGES
104
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA form 2220-1 (9-73)
TOO
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