Refractory bodies as fixed bed coal gasification diluents

United States Patent 1191
1111
Woodmansee
[451 May 21, 1974
[54]
'
REFRACTORY BODIES AS FIXED BED
2,662,007
12/1953
COAL GASIFICATION DILUENTS
2,341,861
2/1944
Fucks . . . . . . . . . . .
2,868,631
1/1959
Woebcke ............................ ,. 48/206
,
[75] Inventory Donald E. Woodmansee,
_ '
Schenectady’ NY‘
.
Attorney, Agent, or Firm-Leo l. MaLossi; Joseph T.
‘ Dec 19 1972
.
Cohen; Jerome O. Squillaro
,
[2 1 ] Appl . No .: 316,454
52
[57]
. ..c1 .................. .. 4
1 Us
4
-
,
Field of Search ‘ _ ' . _ ' _ U 48'/2O"2'
48/206
accommodated by the addition of a diluent to the
[56]
charge "1 °°a1 “1 approximately 11‘ "(Mme mm’ (or
20-4 205
higher) in the form of strong, open-structured bodies.
210. 261,38’ 9 £0 46
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’
1
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’
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ABSTRACT
The swellin g of coal in ?ited. . bed coal gasi?cation is
,
. 8/202’ 8129359 428650368
[51] Int. Cl. .................................... .. cioj 3/16
[58]
. . . . .. 201/38
Assistant Examiner—Peter Kratz
Schenectady, NY.
[22] Filed
Dickinson ........................... .. 48/206
Primary Examiner-Robert L. Lindsay, Jr.
[73] Assignee: General Electric Company,
[
3,811,849
The structures described herein as diluent bodies are
’
hollow refractory cylinders capable of retaining struc
References Cited
tural integrity throughout the pro?le of temperature
UNITED STATES PATENTS
exposure and having cavities large enough to accomo
date the swelling of coal and add porosity to the bed.
3,463,623
8/1969
Forney .................................. .. 48/99
1,030,333
6/1912
Rusby et al. ........................ .. 48/203
C0141.
_ 4 Claims, 1 Drawing Figure
/\
D/LUENT \\
7?: WASHER
‘ "' r- COMBUSTION
.
ZONE
1
3,811,849
REFRACTORY BODIES AS FIXED BED COAL
GASIFICATION DILUENTS
bed during the process. The cavity in the diluent body
must be large enough to accommodate swelling of the
coal and also contribute added porosity to the bed to
promote gas/coal contact. In addition, these refractory
diluent bodies must be capable of surviving repeated
BACKGROUND OF THE INVENTION
Fixed bed coal gasi?ers have been known and used
cycling through the gasi?er and transport apparatus.
and it has been recognized that successful operation
Run-of-mine coal and refractory diluent bodies are
deposited as a mixed charge into gasi?er 10 via hopper
11 in the properproportions (e.g., 50 percent diluent
thereof depends upon using non-caking coals or coke
to accomplish the gasi?cation. When care is not taken .
to limit the ?xed bed composition in this way the swell
by volume and 50 percent coal by volume). The lay
ing of the coal cuts off requisite bed porosity and
ered charge shown has been found to be preferable to
an intimately mixed charge. The coal plus diluent
thereby limits gas-solid contact.
‘
In the ?xed bed coal gasi?cation process, as the coal
moves down to the combustion zone and the refractory
bodies settle on grate 12 with the ash. Ash and refrac
tory bodies are removed from grate 12 to drop into an
ash lockhopper 13 from which they drop down on and
are carried away by conveyor belt 14. At screen 16 the
enters the gasi?er at the top and lands on the top of the
charge, it receives heat from the upwardly moving
product gas. As the combustion process near the bot
tom of the gasi?er consumes some of the coal and the
, rest of the coal is gasi?ed, coal at the top of the charge
gradually moves down passing through a series of treat
ment stages: initial heating; devolatilization and coking;
gasi?cation, and carbon oxidation. A large number of
ash is separated from the refractory bodies, that are
then carried back up to the feeding station for mixing
20 with the coal.
composition is sinterable and the resulting body has
sufficient structural integrity. The cylinders shouldbe
of about l,700° -'- l,900°F. is required. When air and
product is called producer gas; when oxygen and steam
are employed, the end product is called synthesis gas.
‘
The diluent bodies may be made of silicon carbide,
alumina, zirconia, magnesia, etc. as long as the starting
chemical reactions occur and a, minimum temperature
steam are introduced to the combustion zone, the end
2
the bed as these diluent structures move down with the
25 at least about two inches in length with an outer diame
ter of at least about 11/: inches. The hole should provide
signi?cant cavity space and still leave suf?cient wall
thickness for the cylinder to retain strength. The hole
If the product gas is to be burned in a gas turbine, the
should be at least about %-inch I.D.
erosive (particles of ash), corrosive (e.g. Na and K
Exemplary silicon carbide hollow cylinders were pre
compounds) and ammonia must be'removed by wash 30 pared from clay-bonded silicon carbide powder (Car.
mg.
The object of this invention is to ‘be able to utilize
run-of-mine coal regardless of swelling and caking
characteristics in ?xed bed coal gasi?ers. In contrast to
?uid bed coal gasi?ers, the ?xed bed has de?nite ad
vantages, primarily associated with the counter current
movement of the product gas relative to the movement
of the coal in the gasi?er. More sensible heat remains
bofrax No. 4 —- Castable or Ramming Mix — Carbo
rundum Co.). The powder was mixed with a small
amount of water and compacted in a mold under about
10,000 psig in an'arbor press. There was no need to
heat the bodies as directed in the instructions for the
use of this material, since the bodies were strong
, enough to be charged with the coal and they were
thereuponheated in the reducing atmosphere in the
gasi?er itself. The size bodies produced were two
inches long with ll/é-inch OD. and ‘ii-inch I.D.
40
and the coal is devolatilized before it is gasi?ed en
What I claim as new and desire to secure by Letters
abling the volatiles to form part of the product gas.
Patent of the United States is:
in the gasi?er instead of leaving with'the product gas
1. In the process for generating a gas mixture con
' SUMMARY OF THE INVENTION
This invention encompasses means for solvingthe
problem of the swelling and caking of coal in the ?xed
taining combustible components wherein coal and a
45
bed . gasi?cation of coal wherein strong, open
structured bodies are distributed in the coal being
into gas exchange relationship with an upwardly mov
ing gas mixture, the initial gaseous input at the bottom
of said bed being steam and an oxygen-containing gas,
the improvement comprising the step of employing as
the diluent material a plurality of refractory bodies,
said bodies being in the form of hollow cylinders retain
charged to the gasifier. The ratio by volume of diluent
bodies to coal should be at least about 1:1. Hollow re
fractory cylinders have been successfully demonstrated
as diluent bodies in ?xed bed coal gasi?cation with
ing structural integrity throughout the pro?le of tem
perature exposure with the cavity in each body being
large enough to accomodate swelling of said coal and
strongly swelling coals. .
BRIEF DESCRIPTION OF THE DRAWING
This invention is illustrated by 'way of example in the
55 to add porosity to said bed to promote gas-coal contact,
thewyohiwrne raLio of refractory bodies to coal being at
accompanying schematic representation of a coal gas
least about 1:1.
i?er receiving a coal/diluent charge, the diluent being
2. The improvement of claim 1 wherein the refrac
recycled.
DESCRIPTION OF THE PREFERRED
EMBODIMENT
tory material is silicon carbide.
60
Such diluent bodies must have and must retain struc~
tural integrity throughout the temperature pro?le in
order to provide a bed support to minimize crushing of
’
3. The improvement of claim I wherein the hollow
cylinder has an outer diameter of at least about 1%
inches, an inner diameter of at least about three-fourths
inch and a minimum length of at least ‘about 2 inches.
The arrangement shown in the drawingis illustrative
of the process of this invention employing shaped dilu
ent bodies; namely, hollow refractory cylinders.
diluent material distributed relatively uniformly there
through comprise a downwardly moving ‘bed placed
65
4. The improvement of claim 1 wherein the refrac
tory bodies are separated from the coal ash and recy
cled.