CA1095245A - Gasification of carbonaceous solids - Google Patents
Gasification of carbonaceous solidsInfo
- Publication number
- CA1095245A CA1095245A CA280,833A CA280833A CA1095245A CA 1095245 A CA1095245 A CA 1095245A CA 280833 A CA280833 A CA 280833A CA 1095245 A CA1095245 A CA 1095245A
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- Canada
- Prior art keywords
- zone
- heat
- transfer material
- vessel
- solids
- Prior art date
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
- C10J3/46—Gasification of granular or pulverulent flues in suspension
- C10J3/54—Gasification of granular or pulverulent fuels by the Winkler technique, i.e. by fluidisation
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
- C10J3/02—Fixed-bed gasification of lump fuel
- C10J3/06—Continuous processes
- C10J3/12—Continuous processes using solid heat-carriers
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
- C10J3/46—Gasification of granular or pulverulent flues in suspension
- C10J3/48—Apparatus; Plants
- C10J3/482—Gasifiers with stationary fluidised bed
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J2300/00—Details of gasification processes
- C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
- C10J2300/0913—Carbonaceous raw material
- C10J2300/093—Coal
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J2300/00—Details of gasification processes
- C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
- C10J2300/0913—Carbonaceous raw material
- C10J2300/0943—Coke
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J2300/00—Details of gasification processes
- C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
- C10J2300/0913—Carbonaceous raw material
- C10J2300/0946—Waste, e.g. MSW, tires, glass, tar sand, peat, paper, lignite, oil shale
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J2300/00—Details of gasification processes
- C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
- C10J2300/0953—Gasifying agents
- C10J2300/0959—Oxygen
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J2300/00—Details of gasification processes
- C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
- C10J2300/0953—Gasifying agents
- C10J2300/0973—Water
- C10J2300/0976—Water as steam
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J2300/00—Details of gasification processes
- C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
- C10J2300/0983—Additives
- C10J2300/0993—Inert particles, e.g. as heat exchange medium in a fluidized or moving bed, heat carriers, sand
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J2300/00—Details of gasification processes
- C10J2300/18—Details of the gasification process, e.g. loops, autothermal operation
- C10J2300/1807—Recycle loops, e.g. gas, solids, heating medium, water
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Chemistry (AREA)
- Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
GASIFICATION OF CARBONACEOUS SOLIDS
Disclosed is a process and apparatus for the continuous gasification of carbonaceous solids, such as coal, coke, peat, etc. The process involves the downward flow of a fluidized solid particulate heat-transfer material through a vertical vessel countercurrent to the upward flow of a reactive fluidization gas.
Subdivided carbonaceous solids are introduced into a central portion of the vessel and substantially flow downwardly through the vessel and react with the upflowing fluidization gas. The vessel is divided into at least three zones: an upper zone, an intermediate zone, and a lower zone. In the lower zone the fluidization gas is heated by the downflowing solid heat transfer material. In the intermediate zone, the carbonaceous solids react with the fluidization gas forming a product combustible gas and transferring heat to the heat transfer material. In the upper zone, the downflowing heat-transfer material is heated by the upflowing fluidization gas.
GASIFICATION OF CARBONACEOUS SOLIDS
Disclosed is a process and apparatus for the continuous gasification of carbonaceous solids, such as coal, coke, peat, etc. The process involves the downward flow of a fluidized solid particulate heat-transfer material through a vertical vessel countercurrent to the upward flow of a reactive fluidization gas.
Subdivided carbonaceous solids are introduced into a central portion of the vessel and substantially flow downwardly through the vessel and react with the upflowing fluidization gas. The vessel is divided into at least three zones: an upper zone, an intermediate zone, and a lower zone. In the lower zone the fluidization gas is heated by the downflowing solid heat transfer material. In the intermediate zone, the carbonaceous solids react with the fluidization gas forming a product combustible gas and transferring heat to the heat transfer material. In the upper zone, the downflowing heat-transfer material is heated by the upflowing fluidization gas.
Description
E~ACK~ROUND~OF' THE INyENTION
2 The invention relates to the gasification of carbon-
3 aceo~s solids in a single fluidized bed of solid heat~transfer
4 material.
The production of H2 and carbon monoxide from the 6 reaction of steam and oxygen with coal a~d other carbonaceous 1 sollds is a highly endothermic reaction. Similarly, the a volatilization of light hydrocarbons from coal requires a great 9 deal of heat. One of the more attracti~e methods for providing the heat required to carry out the vaporization and reaction 11 involves the use of fluidized beds o~ heat-transfer materials 12 such as char as is shown, for example~ in ~.S~ Patent 3~927,996 13 Typically, bowever, these fluidized bed processes 14 require a second and exEensive separate reaction vessel to heat the heat transfer material to an eLe~ated temperature for 16 injection into the gasification vessel.
17 Another problem ~ith fluidized beds is that the solids 18 are in a turbulent state of motion throughout the bed and there 19 is a great deal o~ top to bottom mixing resulting in a uniform temperature throughout the gasification vessel.
21 Another problem with fluidized bed gasification 22 processes for coal is that some coals upon heating become plastic 23 or tacky which leads tc aglomerization probleQs and the loss of 24 fluidi~ation.
~nother problem with fluidized bed carbonization 26 procecses is that the heavier hydrocarbons evolved from the coal 27 tend to condense and form a sticky mass which ~ends to plug up 28 the vessel and prcduct lines.
29 ~nother probl~m with fluidlzed bed coal processes is that in the crushi~g of the coal a great deal of fines are formed 31 and these fines tend to be entrained ~hrough ~he fluidized bed of 32 neat-transfer material Frior ~o complete reaction. ~
1 Another probl~m encountered in gasificatio~ processes 2 is that of clinker formatlon, particularly in processes wherein 3 comhustion takes Elace in the reaction vessel. If hot spots 4 occur in the vessel, then the coal can exceed the ash fusion temperature and once this happens, large clinkers tend to form in 6 the vessel which freq~ently leads to plugging of the ~essel and 7 shutdown of the process.
8 A further prcblem with the fluidized bed processes is 9 the separation of solids in the fluidi~ed bed ~ith the larger and heavier solids co~centrated at the bottom of t~e bed with the 11 smaller and-lighter sclids at the top of the bed.
12 The present invention overcomes these and other 13 eroblems and provides a gasification proc~ss that is simple to 14 operate and requires a minimum of process equipment.
SUMNARY OF TEIE INVENTION
16 ~ process a~d apparatus for the gasification of carbc~-17 aceous solids in a vertically elongated vessel containing at 18 least three zones~ an upper zone, an intermediate zone, and a 19 lower zone, said process comprising:
(a) introducing into an upper level of said upper zone of 21 said vessel a particulate solid heat-transfer material at a 22 temperature below l200~;
23 (b) maintaining an up~ard flow of a fluidization gas 24 through said vessel at a rate sufficient to mai~tain said heat-transfer material in a fluidized state in said three zones;
26 (c) maintaiDing a subs~an~iall~ net downward flo~ of said 27 heat-transfer material through said three ~ones by ~ithdra~ing 28 from a bottom portion of s~id vessel an effluent stream 29 comprising said heat-transfer material, said heat-transfer material being wi~hdra~n at a temperature helow 1200F;
1 ~d) introducing i~to an upper level of said intermediate 2 zone a stream of subdivided carbonaceous solids which are 3 substantially fluidized by said upflowing rluidization gas and 4 ~hich substantially flc~ downward in said intermediate zone along with said heat-transfer material;
6 (e) reacting said carbonaceous solids with steam and oxyge~
7 in said intermediate zone forming a combustible product gas an 8 heat-transfer material at an elevated temperature in the range 9 1200 to 3000F; and (f) withdrawing from an upper level o~ said upper zone 11 vessel said combustible product gas.
12 B~I~F DESCRIPTION OF THE_DRAWINGS
13 ~IG. 1 is a schematic flow diagram illustrating the 14 flow of gases and solids through the gasification vessel.
FIG. 2 is a diagramatic representation of one 16 temperature profile fcr gases and solids flo~ing through the 17 gasificatio~ vessel.
18 DETAILED_DESCRIPTION O~_THE_INVENTION AN~ PREFERRED EMBODIME~S
19 An object of the present lnvention is to provide an economic process for the gasification of carbonaceous solids to 21 produce a valuable combustible gaseous product.
22 ~ further object of the present in~ention is to provide 23 a simple and continuou~ gasification process and appara~us which 24 requires only one major reaction YesseL~
~nother ob~ct of the present invention is to provide a 26 fluidized bed gasification process which can accommodate a wide 27 size range of carbo~aceous of solids.
28 The process of the present invention will generally be 29 described with reference ~o the processing of coal. However, the process of ~he present i~vention can also be used to gasify, 31 carbonize, and com~ust a ~ide range of carbonaceous solids as 32 defined her2in.
.. . .
1 The term "carbonaceous solids" as defined herein 2 includes coal, coke, ~eat, lignite, oil shale, tar sands, 3 gilsonite, mixtures of two or more of these materials or any 4 other carbonaceous or hydrocarbonaceous containing solids ~ith inert materials, etc.
6 The terms "condensed"t "noncondensable", "normally 7 gaseous" or "normally liquid" as used herein are relative to the 8 conditio~ of the material at 77F (25C) and one at~osphere.
9 The term 'Igasification" is used in the present invention to mean any Frocess wherein a carbonaceous solid reacts 11 with a yas, such as by the endothermic reaction of coal with 12 steam or the exothermic combustion of coal.
13 All mesh si~es in the present specificatio~ are 14 relative to the Tyler Standard Sieve Series.
The process cf tha present invention is best understood 16 by reference to the acccmpanying figures.
17 In FIG. 1, sa~d or some other fluidizable, particulats 18 solid heat tra~sfer material is i~troduced by co~entional means 19 via conduit 1 int~ an upper level o the upper æone of a sub-stantially vertical, elongated gasificatio~ ~essel 2~
21 The heat transfer material can be composed of numerous 22 substances, for example, sand, steel or ceramic balis~ spent 23 shale, etc. Preferably~ the heat-transfer material is inert a~d 24 comprises sand. ~referabLy, the heat-transfer material is of a 2~ relatively u~iform size so that it is easily fluidized in the 26 vessel and can eacily tra~el through the various zonas of the 27 vessel as describ~d he~ei~after. The size of the heat-transfer 28 material ca~ vary ~idely, but generally whe~ using sand, which is 29 the preferred heat-traDsfer material, the si~e ~ill range from about 5 to 20 mesh. ~he heat tra~s~er materi~l is i~troduced at 31 a relativaly cold tsmE~ature belo~ 1200~P and preferably in the ~ . . ~ . . . :, ' ' ' ! .
2~5 1 range 200 to 800~, and more preferably 500 to 700F.
3 The gasification vessel is substantially vertical and 4 is divided into at least three zones, an upper zone, an intermediate zone, and a lower zone, indicated in FIG. 1 by the 6 letters ~, B, and C.
7 The ~arious 20nes of the ~essel are di~ided by conven-8 tional means, such as by perforate antimixing plates or baffles 9 3. The zones prevent gross top to bottom mixing of solids throughout the entire lcngth of the vessel~ The antimixing and 11 zone separation means, however, allo~ ~he flow of solids and 12 gases between the variaus zones of the vessel while inhibiting 13 the rapid circulation af solids between the zones. The height of 14 each zone is designed ta accomplish the reactions and heat-transfer as described hereina~ter in the specification~
16 Sand is maintained in a fluidized state throughout the 17 various zones of the ~essel by the up~ard flow of a fluidi~ation 18 gas through the v~ssel~ The fluidization gas is introduced by 19 conYentional means, such as by conduit 4 into a lower le~el of zone C and flows upward at a rate suf~icient to maintain the 21 heat~transfer mate~ial i~ a ~luidized state throughout zones A, B
22 and C. ~he gaseous flo~ rate through the vessel ca~ vary widely 23 depending on many interrelated factors, but will generàlly be i~
24 the range of 0.5 to 2a ~t/sec and preferably 1 to 5 ft/sec.
A critical feature of the present invention is the 26 substantially net doun~ard movement of the sand through the 27 various zones of the vessel in a fluidized state. A net downward 28 flow of heat-transfer material through the upper, inter~ediate 29 and lower zones o~ the vessel is maintained by withdrawing heat-transfer material from a bottom portion of the vessel via conduit 31 1. ~he sand is the~ con~eyed by conventional means, such as by 24~i 1 the use of a lift gas, tc the top of the vessel and reintroduced 2 into the upper zone. Ihe net downward flow of *he sand can vary 3 from aDout o. 1 to 15 ft/~in, but more typically it will be in the 4 range 0.2 to 5 ft/min. The net downward flow of the sand in a fluidized state serYes many important functions. ~irst, in the 6 usual fluidized bed, the temperature of the bed is essentially 7 uni~orm throughout thP entire bed due to the rapid top to bottom 8 mixing of solids; ho~ever, in the present invention, a 9 temperature gradient results in each zone of the vessel d~ue to the rapid net down~ard movement of solids which tends to 11 substantially reduce ~F to bottom mixing in each zone~ The 12 degree to which tcp tc bottom mi~ing in each zone is reduced ~s, 13 of course, dependent u~n the rate at which the sa~d flows 14 through the bed. Seccndly, the net do~nward flow of sand substantially impedes the fLow of entrained coal fines upwardly 16 through the vessel, ~hereas in the usual ~luidized bed process 17 entrained fines would quicXly be transported out of the vessel by 18 the fluidization gas Erior to reaction.
19 Precrus~ed carbonaceous solids, preferably coal, are introduced by conve~tional mea~s, such as by a screw feeder, into 21 an upper le~el of the i~termediate zone ~ via line 5.
22 SuDstantially all of the carbonaceous solids are fluidized by the 23 up~lowing fluidization gas. The subdivided carbonaceous solids 24 are sized such that in a "stationary" fluidized bed of heat-transfer material, at least 75 weight percent, and preferably at 26 least 90 weigh~ percent, of said solids are fluidized in said bed 27 and less tha~ 10 weight percent and pre~erably less than 5 Yeight 28 percent are antrained ~hrough the fluidized bed of the heat-29 transfer ~aterial. Entrainable carbonaceous fines mustr in general, be avoided since ~hey are rapidly swept out of the 31 intermediate zone and out of the ~ess!al prior to reaction with -.,. ~," ,~ .. .
3,5~5 1 the fluidizing gas thus representing a carbon loss and thermal 2 efficiency penalty. Preferably, less than 10 weight percent and 3 more preferably less than S weight percent of the carbonaceous 4 solids are too large or heavy not to be fluidized by the upflowing fluidization gas. By l~stationary fluidized bed" it is 6 meant that there is ~o net upward or downward movement of s.olids 7 in the vessel. As previously described a net do~n~ard movement 3 of solids results from constan~ ~ithdrawal and introduction of 9 solids from opposite ends of the vessel. Two or more gasification vessels can be ~tilized to process a sertain 11 particle size range~ of interest~ the main difference between the 12 vessels being the size of the heat-transfer material, the size of 13 the carbonaceous solids and the flo~ rate of the fluidizing gas.
14 ~ representative temperature profile for the process is sho~n in FIG. 2~ The gas and heat-transfer material temperatures 16 are shown by curve D~ and the carbonaceous solid temperatures are 17 show~ by curve E. The curves in FIG. 2 are merely representative 18 and the actual temperature profiles can he varied widely 19 depending on all of the ~any interrelated variables.
As the coal flows downward in zone B, it is fluidized 21 by the upflowing fluidization gas. The downward flowing coal is 22 rapidly heated by contact with the heat-transfer material and the 23 upflo~ing fluidization gas and the coal ini~ially undergoes 24 carbonization (pyrolysis)~ As the coal is heated~ it moves down~ard through the vessel and undergoes endother~ic 26 gasification reactions ~ith the steam and combustion gases.
~7 Finally~ a portion of the coal is burned with oxygen in a lover 28 portion of zone B to provide the heat for the endothermic 29 gasificatlon reactions and carbonization taking place in the upper portions of zone B. The coal is preferably in~roduced at 31 ambient temperature. Preferably, the coal is ~ot heated above ..
. .
1 the ash fusion temperature of the coal which will ~ary greatly 2 depending on the type cf coal. Sand flowing downward from the 3 combustion portion of zone B is very hot ~2000-3000F) and it is 4 used to preheat the u~floving ~luidization gas which, i~ ~one C, will preferably camprise a ~ixture of steam and a free oxygen-6 con~ainin~ gas. Ihe heat-transfer material is withdrawn by 1 conventional means frGm the bottom of the vessel at a relatively 8 cool temperature below ~200F and preferably in the range 200 to 9 800~F and more preferably 500 to 700F and it is conveyed by conventional means, for example, by a lift gas to the top of the 11 vessel and reintrcduced into the vessel and recycled through the 12 vessel.
13 The fluidization gas, of course, changes temperature 14 and composition as it Fasses through ~he vesselO The fluidization gas is introduced into a hottom portion of the 16 vessel and flows upward through zones C, B and A, respectively, 17 maintaining the solids in a fluidized state. The steam and ~8 oxyge~-csntaining portiGns of the fluidization gas react with the 19 carbonaceo~s solids in the intermediate zone forming a product combustible gas ~ich ~ecomes part of the fluidization gas~
21 Preferably, the fluidlzation gas ls introduced at a temperature 22 in the range of 100 to 600F, preferably 300 to 500F. The 23 fluidization gas, as i~troduced, may be an inert gas but 24 preferably comprises a ~i~ture o~ steam and a free oxygen-containing gas. $he amount of steam and free oxygen are varied 26 in order to obtain the d~sired temperature profile i~ the vessel.
27 ~he steam aud o~ygen-contai~ing gases can be introduced 28 separately, f so desiredt or introduced directly into zo~e ~.
2g Gases can, o~ course, be ~ithdraw~n or added to any of the gases i3 order to maintain the solids i~ the desired fluidized state~
31 ~he amount of oxygen is controlled to combust a sufficient _ g _ ~s~
1 portion of the carbonaceous solids so as to provide the necessary 2 heat ~or the endothar~ic gasificatio~ reactions and carboniza~ion 3 occurring in zone B. In addition to burning a portion of the 4 carbonaceous material, the carbon deposits on the sand are also burned.
6 As ~he fl~idization gas passes upwardly through zone C, 7 it is heated to an elevated temperature in the range 500 to 8 1500~F by the hot downflowing sand. Upon entering zone B~ the 9 oxygen reacts with the coal forming CO, COz and the temperature of the fluidizatlcn gas and the heat-transfer material increases 11 rapidly to an elevated te~perature in the range of 1200 to 3000F
12 and preferably 1800 to 2500F. Preferably, all of the oxygen i5 13 consumed in the lower pcrtion of zone ~ such that the gas is 14 essentially non-ccmbustlon supporting as it passes through the upper portions of zone B and into zone A. The fluidization gas 16 then passes through zone C wherein it is cooled to a lower 17 te~p~ratura belov 1200~F and pre~erably in the range 200 to 800F
18 by contact with the downflowing heat-transrer material. The 19 fluidizatiou gas, upon being wi-thdrawn from an upper level of the upper zone via conduit 6, for example, comprises a combustlble 21 product gas containing Hz, CO, CO2 and gaseous light 22 hydrocarbons. The light hydrccarbons will principally comprise 23 methane, ethane a~d propane. Small amounts of higher boiling 24 hydrocarbons may also b~ present in the effluent stream. The effluent stream will also contain entrained, finely divided solids comprising the ash from the coal.
27 As the coal undergoes carbonization, endothermic 28 gasification reactions and e~othermic combustion reactions the 29 coal is reduced in size to the point where the residual remaining solids, commsnly called ash, are entrained up~ardly through the 31 vessel alo~g with the fluidization gases. The ash and any other - 10 ~
1'' .
s 1 solid fines are separated from the gaseous product by 2 conventional m6anst for example, by a cyclone separator located 3 inside or outside the vessel.
4 ~s the sand moves downwardly through zone ~f the heavier hydrocarbcns initially vaporized in zone B are entrained 6 upward and are cracked~ producing lower boiling hydrocarbons. As 7 this cracking occurs, carbon will be deposited on the do~nflowing 8 sand. This carbon then enothermically reacts with the steam in 9 the gasification zone forminy additional light hydrocarbons or is combust~d providing additional heat for the process~
11 Preferably, the process is kept in heat ~alance, such lZ that the heat reguired for the endothermic reactions is supplied 13 by the exothermic reactions. Ho~ever, if excess heat is 14 generated, then ~he heat can be removed from the process by the insertion of heat^transfer coils in zone C which can be used for 16 production of steam useful in other processes. Heat-transfer 17 coils in zone C can also be used to produce the steam for the 18 process of the pr~sent invention.
19 The degree to which carbonization, endo-thermic gasification and combustion are separated in zone B will depend 21 on many interrelated factors. Primarily, hoNever, the degree of 22 separation of these three processes will depend upon three 23 factors: First, the rate o~ the net downward flow of heat-24 transEer material thrcugh the zone. Secondly~ the length of zone B and thirdly, the amount of oxygen present in the fluidization 26 gas relati~e to the amount of coal being fed into the vessel.
27 Higher rates of the net downflow of heat~transfer material 28 reduces the degree of top to bottom mixing in each zone. This 29 increases the thermal gradient in each zone and increases the degree of separation of carbonization, endothermic gasification 31 and combustion. ~he longer zone ~ is, si~ilarly, reduces top to 1 bottom mixing and increases the thermal gradi~nt in the zone. If 2 the oxygen content in the upflowing gas is too high, then 3 combustion will nct be limited to the lower portion of zone 8 but 4 will continue until all of ~ha oxygen is consumed. Thus, the degree of combustion ic basically limited by the o~ygen content 6 of the fluidizaticn gas.
7 The degree cf separation of carbonizatio~, endothermic 8 gasification and ~xothermic gasification in zone B can also be 9 increased by the insertios of additional antimixing baffles in zone B as previously 2iscussed in refere~ce to the separation of 11 zones ~, B a~d C.
12 The process cf the present invention offers many ad-13 vantages over pricr art processes, more specificall~:
14 (1) By the intrcduction o~ the carbonaceous solids at a level ~ell below the tcF of the fluidi7ed bed of heat-transfer 16 material, coupled ~ith the net do~nward movement of the fluidized 17 heat~tra~sfer material, the residence time o~ rines which would 18 normally be rapidly sweEt out of the vessel prior to reaction is 19 increasad significantly so that the volatile hydrocarbons in the fines are at least vapcrized~
21 (2) In addition tc serving as a heat-transfer ~o~e, the 22 uppeI portion of the fluidized bed of heat-transfer material also 23 serves as a cracking zone for the cracking of the heavier 24 hydrocarbons to lighter hydrocarbons. This cracking results in coke deposits on the heat~tra~sfer material and as the heat-26 transfer material is carried dow~ward through the vessel, -the 27 coke reacts with the upflowing steam forming additional light 2~ hydrocarbons or reacts ~ith oxygen providing additional heat for ~9 the process.
(3~ The process i~ very si~ple because all the heat 31 re~uirements for the Frccess can be generated in a single ~essel 32 by halancing the endotbermic and exothermic reactions.
.
10'35Z~S
1 (4) The pxocess Ercvides for a high throughput of solids 2 for a relatively small sized vessel which results in substantial 3 reduction in capital cocts.
-- ~3 --
The production of H2 and carbon monoxide from the 6 reaction of steam and oxygen with coal a~d other carbonaceous 1 sollds is a highly endothermic reaction. Similarly, the a volatilization of light hydrocarbons from coal requires a great 9 deal of heat. One of the more attracti~e methods for providing the heat required to carry out the vaporization and reaction 11 involves the use of fluidized beds o~ heat-transfer materials 12 such as char as is shown, for example~ in ~.S~ Patent 3~927,996 13 Typically, bowever, these fluidized bed processes 14 require a second and exEensive separate reaction vessel to heat the heat transfer material to an eLe~ated temperature for 16 injection into the gasification vessel.
17 Another problem ~ith fluidized beds is that the solids 18 are in a turbulent state of motion throughout the bed and there 19 is a great deal o~ top to bottom mixing resulting in a uniform temperature throughout the gasification vessel.
21 Another problem with fluidized bed gasification 22 processes for coal is that some coals upon heating become plastic 23 or tacky which leads tc aglomerization probleQs and the loss of 24 fluidi~ation.
~nother problem with fluidized bed carbonization 26 procecses is that the heavier hydrocarbons evolved from the coal 27 tend to condense and form a sticky mass which ~ends to plug up 28 the vessel and prcduct lines.
29 ~nother probl~m with fluidlzed bed coal processes is that in the crushi~g of the coal a great deal of fines are formed 31 and these fines tend to be entrained ~hrough ~he fluidized bed of 32 neat-transfer material Frior ~o complete reaction. ~
1 Another probl~m encountered in gasificatio~ processes 2 is that of clinker formatlon, particularly in processes wherein 3 comhustion takes Elace in the reaction vessel. If hot spots 4 occur in the vessel, then the coal can exceed the ash fusion temperature and once this happens, large clinkers tend to form in 6 the vessel which freq~ently leads to plugging of the ~essel and 7 shutdown of the process.
8 A further prcblem with the fluidized bed processes is 9 the separation of solids in the fluidi~ed bed ~ith the larger and heavier solids co~centrated at the bottom of t~e bed with the 11 smaller and-lighter sclids at the top of the bed.
12 The present invention overcomes these and other 13 eroblems and provides a gasification proc~ss that is simple to 14 operate and requires a minimum of process equipment.
SUMNARY OF TEIE INVENTION
16 ~ process a~d apparatus for the gasification of carbc~-17 aceous solids in a vertically elongated vessel containing at 18 least three zones~ an upper zone, an intermediate zone, and a 19 lower zone, said process comprising:
(a) introducing into an upper level of said upper zone of 21 said vessel a particulate solid heat-transfer material at a 22 temperature below l200~;
23 (b) maintaining an up~ard flow of a fluidization gas 24 through said vessel at a rate sufficient to mai~tain said heat-transfer material in a fluidized state in said three zones;
26 (c) maintaiDing a subs~an~iall~ net downward flo~ of said 27 heat-transfer material through said three ~ones by ~ithdra~ing 28 from a bottom portion of s~id vessel an effluent stream 29 comprising said heat-transfer material, said heat-transfer material being wi~hdra~n at a temperature helow 1200F;
1 ~d) introducing i~to an upper level of said intermediate 2 zone a stream of subdivided carbonaceous solids which are 3 substantially fluidized by said upflowing rluidization gas and 4 ~hich substantially flc~ downward in said intermediate zone along with said heat-transfer material;
6 (e) reacting said carbonaceous solids with steam and oxyge~
7 in said intermediate zone forming a combustible product gas an 8 heat-transfer material at an elevated temperature in the range 9 1200 to 3000F; and (f) withdrawing from an upper level o~ said upper zone 11 vessel said combustible product gas.
12 B~I~F DESCRIPTION OF THE_DRAWINGS
13 ~IG. 1 is a schematic flow diagram illustrating the 14 flow of gases and solids through the gasification vessel.
FIG. 2 is a diagramatic representation of one 16 temperature profile fcr gases and solids flo~ing through the 17 gasificatio~ vessel.
18 DETAILED_DESCRIPTION O~_THE_INVENTION AN~ PREFERRED EMBODIME~S
19 An object of the present lnvention is to provide an economic process for the gasification of carbonaceous solids to 21 produce a valuable combustible gaseous product.
22 ~ further object of the present in~ention is to provide 23 a simple and continuou~ gasification process and appara~us which 24 requires only one major reaction YesseL~
~nother ob~ct of the present invention is to provide a 26 fluidized bed gasification process which can accommodate a wide 27 size range of carbo~aceous of solids.
28 The process of the present invention will generally be 29 described with reference ~o the processing of coal. However, the process of ~he present i~vention can also be used to gasify, 31 carbonize, and com~ust a ~ide range of carbonaceous solids as 32 defined her2in.
.. . .
1 The term "carbonaceous solids" as defined herein 2 includes coal, coke, ~eat, lignite, oil shale, tar sands, 3 gilsonite, mixtures of two or more of these materials or any 4 other carbonaceous or hydrocarbonaceous containing solids ~ith inert materials, etc.
6 The terms "condensed"t "noncondensable", "normally 7 gaseous" or "normally liquid" as used herein are relative to the 8 conditio~ of the material at 77F (25C) and one at~osphere.
9 The term 'Igasification" is used in the present invention to mean any Frocess wherein a carbonaceous solid reacts 11 with a yas, such as by the endothermic reaction of coal with 12 steam or the exothermic combustion of coal.
13 All mesh si~es in the present specificatio~ are 14 relative to the Tyler Standard Sieve Series.
The process cf tha present invention is best understood 16 by reference to the acccmpanying figures.
17 In FIG. 1, sa~d or some other fluidizable, particulats 18 solid heat tra~sfer material is i~troduced by co~entional means 19 via conduit 1 int~ an upper level o the upper æone of a sub-stantially vertical, elongated gasificatio~ ~essel 2~
21 The heat transfer material can be composed of numerous 22 substances, for example, sand, steel or ceramic balis~ spent 23 shale, etc. Preferably~ the heat-transfer material is inert a~d 24 comprises sand. ~referabLy, the heat-transfer material is of a 2~ relatively u~iform size so that it is easily fluidized in the 26 vessel and can eacily tra~el through the various zonas of the 27 vessel as describ~d he~ei~after. The size of the heat-transfer 28 material ca~ vary ~idely, but generally whe~ using sand, which is 29 the preferred heat-traDsfer material, the si~e ~ill range from about 5 to 20 mesh. ~he heat tra~s~er materi~l is i~troduced at 31 a relativaly cold tsmE~ature belo~ 1200~P and preferably in the ~ . . ~ . . . :, ' ' ' ! .
2~5 1 range 200 to 800~, and more preferably 500 to 700F.
3 The gasification vessel is substantially vertical and 4 is divided into at least three zones, an upper zone, an intermediate zone, and a lower zone, indicated in FIG. 1 by the 6 letters ~, B, and C.
7 The ~arious 20nes of the ~essel are di~ided by conven-8 tional means, such as by perforate antimixing plates or baffles 9 3. The zones prevent gross top to bottom mixing of solids throughout the entire lcngth of the vessel~ The antimixing and 11 zone separation means, however, allo~ ~he flow of solids and 12 gases between the variaus zones of the vessel while inhibiting 13 the rapid circulation af solids between the zones. The height of 14 each zone is designed ta accomplish the reactions and heat-transfer as described hereina~ter in the specification~
16 Sand is maintained in a fluidized state throughout the 17 various zones of the ~essel by the up~ard flow of a fluidi~ation 18 gas through the v~ssel~ The fluidization gas is introduced by 19 conYentional means, such as by conduit 4 into a lower le~el of zone C and flows upward at a rate suf~icient to maintain the 21 heat~transfer mate~ial i~ a ~luidized state throughout zones A, B
22 and C. ~he gaseous flo~ rate through the vessel ca~ vary widely 23 depending on many interrelated factors, but will generàlly be i~
24 the range of 0.5 to 2a ~t/sec and preferably 1 to 5 ft/sec.
A critical feature of the present invention is the 26 substantially net doun~ard movement of the sand through the 27 various zones of the vessel in a fluidized state. A net downward 28 flow of heat-transfer material through the upper, inter~ediate 29 and lower zones o~ the vessel is maintained by withdrawing heat-transfer material from a bottom portion of the vessel via conduit 31 1. ~he sand is the~ con~eyed by conventional means, such as by 24~i 1 the use of a lift gas, tc the top of the vessel and reintroduced 2 into the upper zone. Ihe net downward flow of *he sand can vary 3 from aDout o. 1 to 15 ft/~in, but more typically it will be in the 4 range 0.2 to 5 ft/min. The net downward flow of the sand in a fluidized state serYes many important functions. ~irst, in the 6 usual fluidized bed, the temperature of the bed is essentially 7 uni~orm throughout thP entire bed due to the rapid top to bottom 8 mixing of solids; ho~ever, in the present invention, a 9 temperature gradient results in each zone of the vessel d~ue to the rapid net down~ard movement of solids which tends to 11 substantially reduce ~F to bottom mixing in each zone~ The 12 degree to which tcp tc bottom mi~ing in each zone is reduced ~s, 13 of course, dependent u~n the rate at which the sa~d flows 14 through the bed. Seccndly, the net do~nward flow of sand substantially impedes the fLow of entrained coal fines upwardly 16 through the vessel, ~hereas in the usual ~luidized bed process 17 entrained fines would quicXly be transported out of the vessel by 18 the fluidization gas Erior to reaction.
19 Precrus~ed carbonaceous solids, preferably coal, are introduced by conve~tional mea~s, such as by a screw feeder, into 21 an upper le~el of the i~termediate zone ~ via line 5.
22 SuDstantially all of the carbonaceous solids are fluidized by the 23 up~lowing fluidization gas. The subdivided carbonaceous solids 24 are sized such that in a "stationary" fluidized bed of heat-transfer material, at least 75 weight percent, and preferably at 26 least 90 weigh~ percent, of said solids are fluidized in said bed 27 and less tha~ 10 weight percent and pre~erably less than 5 Yeight 28 percent are antrained ~hrough the fluidized bed of the heat-29 transfer ~aterial. Entrainable carbonaceous fines mustr in general, be avoided since ~hey are rapidly swept out of the 31 intermediate zone and out of the ~ess!al prior to reaction with -.,. ~," ,~ .. .
3,5~5 1 the fluidizing gas thus representing a carbon loss and thermal 2 efficiency penalty. Preferably, less than 10 weight percent and 3 more preferably less than S weight percent of the carbonaceous 4 solids are too large or heavy not to be fluidized by the upflowing fluidization gas. By l~stationary fluidized bed" it is 6 meant that there is ~o net upward or downward movement of s.olids 7 in the vessel. As previously described a net do~n~ard movement 3 of solids results from constan~ ~ithdrawal and introduction of 9 solids from opposite ends of the vessel. Two or more gasification vessels can be ~tilized to process a sertain 11 particle size range~ of interest~ the main difference between the 12 vessels being the size of the heat-transfer material, the size of 13 the carbonaceous solids and the flo~ rate of the fluidizing gas.
14 ~ representative temperature profile for the process is sho~n in FIG. 2~ The gas and heat-transfer material temperatures 16 are shown by curve D~ and the carbonaceous solid temperatures are 17 show~ by curve E. The curves in FIG. 2 are merely representative 18 and the actual temperature profiles can he varied widely 19 depending on all of the ~any interrelated variables.
As the coal flows downward in zone B, it is fluidized 21 by the upflowing fluidization gas. The downward flowing coal is 22 rapidly heated by contact with the heat-transfer material and the 23 upflo~ing fluidization gas and the coal ini~ially undergoes 24 carbonization (pyrolysis)~ As the coal is heated~ it moves down~ard through the vessel and undergoes endother~ic 26 gasification reactions ~ith the steam and combustion gases.
~7 Finally~ a portion of the coal is burned with oxygen in a lover 28 portion of zone B to provide the heat for the endothermic 29 gasificatlon reactions and carbonization taking place in the upper portions of zone B. The coal is preferably in~roduced at 31 ambient temperature. Preferably, the coal is ~ot heated above ..
. .
1 the ash fusion temperature of the coal which will ~ary greatly 2 depending on the type cf coal. Sand flowing downward from the 3 combustion portion of zone B is very hot ~2000-3000F) and it is 4 used to preheat the u~floving ~luidization gas which, i~ ~one C, will preferably camprise a ~ixture of steam and a free oxygen-6 con~ainin~ gas. Ihe heat-transfer material is withdrawn by 1 conventional means frGm the bottom of the vessel at a relatively 8 cool temperature below ~200F and preferably in the range 200 to 9 800~F and more preferably 500 to 700F and it is conveyed by conventional means, for example, by a lift gas to the top of the 11 vessel and reintrcduced into the vessel and recycled through the 12 vessel.
13 The fluidization gas, of course, changes temperature 14 and composition as it Fasses through ~he vesselO The fluidization gas is introduced into a hottom portion of the 16 vessel and flows upward through zones C, B and A, respectively, 17 maintaining the solids in a fluidized state. The steam and ~8 oxyge~-csntaining portiGns of the fluidization gas react with the 19 carbonaceo~s solids in the intermediate zone forming a product combustible gas ~ich ~ecomes part of the fluidization gas~
21 Preferably, the fluidlzation gas ls introduced at a temperature 22 in the range of 100 to 600F, preferably 300 to 500F. The 23 fluidization gas, as i~troduced, may be an inert gas but 24 preferably comprises a ~i~ture o~ steam and a free oxygen-containing gas. $he amount of steam and free oxygen are varied 26 in order to obtain the d~sired temperature profile i~ the vessel.
27 ~he steam aud o~ygen-contai~ing gases can be introduced 28 separately, f so desiredt or introduced directly into zo~e ~.
2g Gases can, o~ course, be ~ithdraw~n or added to any of the gases i3 order to maintain the solids i~ the desired fluidized state~
31 ~he amount of oxygen is controlled to combust a sufficient _ g _ ~s~
1 portion of the carbonaceous solids so as to provide the necessary 2 heat ~or the endothar~ic gasificatio~ reactions and carboniza~ion 3 occurring in zone B. In addition to burning a portion of the 4 carbonaceous material, the carbon deposits on the sand are also burned.
6 As ~he fl~idization gas passes upwardly through zone C, 7 it is heated to an elevated temperature in the range 500 to 8 1500~F by the hot downflowing sand. Upon entering zone B~ the 9 oxygen reacts with the coal forming CO, COz and the temperature of the fluidizatlcn gas and the heat-transfer material increases 11 rapidly to an elevated te~perature in the range of 1200 to 3000F
12 and preferably 1800 to 2500F. Preferably, all of the oxygen i5 13 consumed in the lower pcrtion of zone ~ such that the gas is 14 essentially non-ccmbustlon supporting as it passes through the upper portions of zone B and into zone A. The fluidization gas 16 then passes through zone C wherein it is cooled to a lower 17 te~p~ratura belov 1200~F and pre~erably in the range 200 to 800F
18 by contact with the downflowing heat-transrer material. The 19 fluidizatiou gas, upon being wi-thdrawn from an upper level of the upper zone via conduit 6, for example, comprises a combustlble 21 product gas containing Hz, CO, CO2 and gaseous light 22 hydrocarbons. The light hydrccarbons will principally comprise 23 methane, ethane a~d propane. Small amounts of higher boiling 24 hydrocarbons may also b~ present in the effluent stream. The effluent stream will also contain entrained, finely divided solids comprising the ash from the coal.
27 As the coal undergoes carbonization, endothermic 28 gasification reactions and e~othermic combustion reactions the 29 coal is reduced in size to the point where the residual remaining solids, commsnly called ash, are entrained up~ardly through the 31 vessel alo~g with the fluidization gases. The ash and any other - 10 ~
1'' .
s 1 solid fines are separated from the gaseous product by 2 conventional m6anst for example, by a cyclone separator located 3 inside or outside the vessel.
4 ~s the sand moves downwardly through zone ~f the heavier hydrocarbcns initially vaporized in zone B are entrained 6 upward and are cracked~ producing lower boiling hydrocarbons. As 7 this cracking occurs, carbon will be deposited on the do~nflowing 8 sand. This carbon then enothermically reacts with the steam in 9 the gasification zone forminy additional light hydrocarbons or is combust~d providing additional heat for the process~
11 Preferably, the process is kept in heat ~alance, such lZ that the heat reguired for the endothermic reactions is supplied 13 by the exothermic reactions. Ho~ever, if excess heat is 14 generated, then ~he heat can be removed from the process by the insertion of heat^transfer coils in zone C which can be used for 16 production of steam useful in other processes. Heat-transfer 17 coils in zone C can also be used to produce the steam for the 18 process of the pr~sent invention.
19 The degree to which carbonization, endo-thermic gasification and combustion are separated in zone B will depend 21 on many interrelated factors. Primarily, hoNever, the degree of 22 separation of these three processes will depend upon three 23 factors: First, the rate o~ the net downward flow of heat-24 transEer material thrcugh the zone. Secondly~ the length of zone B and thirdly, the amount of oxygen present in the fluidization 26 gas relati~e to the amount of coal being fed into the vessel.
27 Higher rates of the net downflow of heat~transfer material 28 reduces the degree of top to bottom mixing in each zone. This 29 increases the thermal gradient in each zone and increases the degree of separation of carbonization, endothermic gasification 31 and combustion. ~he longer zone ~ is, si~ilarly, reduces top to 1 bottom mixing and increases the thermal gradi~nt in the zone. If 2 the oxygen content in the upflowing gas is too high, then 3 combustion will nct be limited to the lower portion of zone 8 but 4 will continue until all of ~ha oxygen is consumed. Thus, the degree of combustion ic basically limited by the o~ygen content 6 of the fluidizaticn gas.
7 The degree cf separation of carbonizatio~, endothermic 8 gasification and ~xothermic gasification in zone B can also be 9 increased by the insertios of additional antimixing baffles in zone B as previously 2iscussed in refere~ce to the separation of 11 zones ~, B a~d C.
12 The process cf the present invention offers many ad-13 vantages over pricr art processes, more specificall~:
14 (1) By the intrcduction o~ the carbonaceous solids at a level ~ell below the tcF of the fluidi7ed bed of heat-transfer 16 material, coupled ~ith the net do~nward movement of the fluidized 17 heat~tra~sfer material, the residence time o~ rines which would 18 normally be rapidly sweEt out of the vessel prior to reaction is 19 increasad significantly so that the volatile hydrocarbons in the fines are at least vapcrized~
21 (2) In addition tc serving as a heat-transfer ~o~e, the 22 uppeI portion of the fluidized bed of heat-transfer material also 23 serves as a cracking zone for the cracking of the heavier 24 hydrocarbons to lighter hydrocarbons. This cracking results in coke deposits on the heat~tra~sfer material and as the heat-26 transfer material is carried dow~ward through the vessel, -the 27 coke reacts with the upflowing steam forming additional light 2~ hydrocarbons or reacts ~ith oxygen providing additional heat for ~9 the process.
(3~ The process i~ very si~ple because all the heat 31 re~uirements for the Frccess can be generated in a single ~essel 32 by halancing the endotbermic and exothermic reactions.
.
10'35Z~S
1 (4) The pxocess Ercvides for a high throughput of solids 2 for a relatively small sized vessel which results in substantial 3 reduction in capital cocts.
-- ~3 --
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A continuous process for the gasification of carbonaceous solids in a vertically elongated vessel containing at least three zones, an upper zone, an intermediate zone, and a lower zone, said process comprising:
(a) introducing into an upper level of said upper zone of said vessel a particulate solid heat-transfer material at a temperature below 1200°F;
(b) maintaining an upward flow of a fluidization gas through said vessel at a rate sufficient to maintain said heat-transfer material in a fluidized state in said three zones;
(c) maintaining a substantially net downward flow of said heat-transfer material through said three zones in the range of 0.1 to 15 ft./min. by withdrawing from a bottom portion of said vessel an effluent stream comprising said heat-transfer material, said heat-transfer material being withdrawn at a temperature below 1200°F;
(d) introducing into an upper level of said intermediate zone a stream of subdivided carbonaceous solids which are substantially fluidized by said upflowing fluidization gas and which substantially flow downward in said intermediate zone along with said heat-transfer material;
(e) reacting said carbonaceous solids with steam and oxygen in said intermediate zone forming a combustible product gas and heating the heat-transfer material to an elevated temperature in the range 1200 to 3000°F; and (f) withdrawing from an upper level of said upper zone vessel said combustible product gas.
(a) introducing into an upper level of said upper zone of said vessel a particulate solid heat-transfer material at a temperature below 1200°F;
(b) maintaining an upward flow of a fluidization gas through said vessel at a rate sufficient to maintain said heat-transfer material in a fluidized state in said three zones;
(c) maintaining a substantially net downward flow of said heat-transfer material through said three zones in the range of 0.1 to 15 ft./min. by withdrawing from a bottom portion of said vessel an effluent stream comprising said heat-transfer material, said heat-transfer material being withdrawn at a temperature below 1200°F;
(d) introducing into an upper level of said intermediate zone a stream of subdivided carbonaceous solids which are substantially fluidized by said upflowing fluidization gas and which substantially flow downward in said intermediate zone along with said heat-transfer material;
(e) reacting said carbonaceous solids with steam and oxygen in said intermediate zone forming a combustible product gas and heating the heat-transfer material to an elevated temperature in the range 1200 to 3000°F; and (f) withdrawing from an upper level of said upper zone vessel said combustible product gas.
2. The process of Claim 1 wherein said fluidization gas initially comprises steam and molecular oxygen.
3. The process of Claim 1 wherein said carbonaceous solids comprise coal.
4. The process of Claim 1 wherein said heat-transfer material is inert.
5. The process of Claim 3 wherein said heat-transfer material comprises sand.
6. The process of Claim 3 wherein said heat-transfer material is introduced and withdrawn from said vessel at a temp-erature in the range 500 to 700°F.
7. The process of Claim 1 wherein at least 75 weight percent of said carbonaceous solids are fluidized by said fluidization gas in said intermediate zone and less than 10 weight percent are entrained by said fluidization gas.
8. The process of Claim 1 wherein an elevated temperature in the range 1800 to 2500°F is maintained in said intermediate zone.
9. Gasification apparatus comprising in combination:
a vertically elongated vessel;
perforate zone separation means dividing said vessel into at least three zones, an upper zone, an intermediate zone, and a lower zone, said zone separation means allowing the passage of gases and solids but inhibiting the rapid circulation of solids between said zones;
means for introducing particulate solid heat-transfer material into an upper level of said upper zone;
means for removing said particulate solid heat-transfer material from a lower level of said lower zone;
means for introducing subdivided carbonaceous solids into an upper level of said intermediate zone;
means for introducing a fluidization gas into a lower level of said lower zone; and means for withdrawing a combustible gaseous product from an upper level of said upper zone.
a vertically elongated vessel;
perforate zone separation means dividing said vessel into at least three zones, an upper zone, an intermediate zone, and a lower zone, said zone separation means allowing the passage of gases and solids but inhibiting the rapid circulation of solids between said zones;
means for introducing particulate solid heat-transfer material into an upper level of said upper zone;
means for removing said particulate solid heat-transfer material from a lower level of said lower zone;
means for introducing subdivided carbonaceous solids into an upper level of said intermediate zone;
means for introducing a fluidization gas into a lower level of said lower zone; and means for withdrawing a combustible gaseous product from an upper level of said upper zone.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US72755776A | 1976-09-28 | 1976-09-28 | |
| US727,557 | 1985-04-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1095245A true CA1095245A (en) | 1981-02-10 |
Family
ID=24923120
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA280,833A Expired CA1095245A (en) | 1976-09-28 | 1977-06-17 | Gasification of carbonaceous solids |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA1095245A (en) |
| DE (1) | DE2742644C2 (en) |
| GB (1) | GB1548472A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI62554C (en) * | 1981-05-22 | 1983-01-10 | Ahlstroem Oy | FARING EQUIPMENT FOR ORGANIZATION OF FAST KOLHALTIGT MATERIAL |
| DE4131962C2 (en) * | 1991-09-25 | 1998-03-26 | Hismelt Corp Pty Ltd | Method and device for treating hot gases with solids in a fluidized bed |
| SE541321C2 (en) * | 2015-03-25 | 2019-07-02 | Vattenfall Ab | Bubbling fluidized bed combustion device and method for monitoring the fluidized bed in such a combustion device |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB593180A (en) * | 1945-06-13 | 1947-10-09 | Michael Henry Miller Arnold | Improvements in and relating to the contacting of solids with solids |
| DE929866C (en) * | 1950-07-09 | 1955-07-04 | Huels Chemische Werke Ag | Process for degassing and / or gasifying solid fuels |
| US2662005A (en) * | 1953-01-12 | 1953-12-08 | Socony Vacuum Oil Co Inc | Gaseous fuel production |
-
1977
- 1977-06-17 CA CA280,833A patent/CA1095245A/en not_active Expired
- 1977-08-18 GB GB34797/77A patent/GB1548472A/en not_active Expired
- 1977-09-22 DE DE2742644A patent/DE2742644C2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE2742644A1 (en) | 1978-03-30 |
| DE2742644C2 (en) | 1987-03-19 |
| GB1548472A (en) | 1979-07-18 |
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