CA1070634A - Fines recycle in a coking process - Google Patents
Fines recycle in a coking processInfo
- Publication number
- CA1070634A CA1070634A CA251,500A CA251500A CA1070634A CA 1070634 A CA1070634 A CA 1070634A CA 251500 A CA251500 A CA 251500A CA 1070634 A CA1070634 A CA 1070634A
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- solids
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- coke
- coking
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Abstract
(U.S. 626,622) ABSTRACT OF THE DISCLOSURE
In a coking process wherein a stream of fluidized solids is passed from a fluidized bed coking zone to a second fluidized bed zone, entrained coke fines recovered by a wet scrubbing process from the gaseous effluent of the second fluidized bed zone are recycled as a solids-liquid slurry of a specified range of concentration to the coking zone.
In a coking process wherein a stream of fluidized solids is passed from a fluidized bed coking zone to a second fluidized bed zone, entrained coke fines recovered by a wet scrubbing process from the gaseous effluent of the second fluidized bed zone are recycled as a solids-liquid slurry of a specified range of concentration to the coking zone.
Description
~070634 :
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to an improvement in a fluid coking process. More particularly, it relates to recycling wet fines to the coking zone of the process.
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to an improvement in a fluid coking process. More particularly, it relates to recycling wet fines to the coking zone of the process.
2. Description of the Prior Art It is known to produce fuel gases by integrated fluid coking and gasification processes such as those dis-closed in U.S. patents 3,661,543; 3,702,516; and 3,759,676, - 10 In these prior art processes, up to about 95~/0 of the gross coke product may be gasified in the gasification zone to a fuel gas.
It has now been found that gasification of the - gross coke product can be increased from about 95 to about 99% by recycling the coke or coke-coated fines recovered from the fuel gas product to the coking zone.
U.S. patent 3~414,504 discloses a fluid coking ` process in which a burner flue gas including entrained coke is combusted with air thereby producing heated dry coke particles which are recycled to the coker directly or in admixture with the oil feed. It should be noted that by the term llfluid coking process'l is intended herein a process which comprises a coking reactor and a burner vessel in which a portion of the coke product is burned to provide the heat requirements -of the process. Such a process is described in U.S. patent 2,881,130.
U.S. patent 3~278,412 discloses a process for fluid coking in which coke-coated tar sands fines recovered from a low temperature burner are burned to remove the coke therefrom and the coke-free fines are subsequently recycled to a coking zone.
:.
: ~, `~' 1070634 It has now been found that wet fines recovered from the gaseous effluent of a zone integrated with the coking zone can be advantageously recycled to the coking zone when the fines are recycled as a wet slurry of a specified concentra-tion, without adversely affecting the process operation in-cluding the particle size distribution of the fluidized solids.
Furthermore, in one embodiment of thé invention wherein the process is an integrated coking and gasification process, the recycled fines permit a higher level of gasification of the gross coke product than heretofore. Recycling the fines also eliminates the coke fines disposal problem.
SUMMARY OF THE INVENTIOM
In accordance with the invention, there is pro-vided in a coking process comprising the steps of:
(a) contacting a carbonaceous material under fluid coking conditions in a coking zone containing a first bed of fluidized solids to form coke, said coke depositing on said fluidized solids;
(b) introducing a portion of said solids with a coke deposition thereon to a second zone containing a second bed I of fluidized solids;
; (c) recovering from said second zone a gaseous stream containing entrained coke solids;
(d) sepa~rating at least a portion of said entrained coke solids from said gaseous stream; and (e) scrubbing the resulting gaseous stream con-taining entrained coke solids with a liquid to form a liquid-solids slurry, characterized by the steps which com-prise:
(f) adjusting the concentration of said liquid-~ 3-, /~
.
~070634 solids slurr~ such that said slurr~ comprises not more than 30 weight percent of said coke solids, based on said slurry, and . -(g) introducing the resulting slurry into said coking zone.
.
` -3a-`- ~07~634 BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic flow plan of one embodi-ment of the invention.
Figure 2 is a graph showing the effect of solids concentration on viscosity at 76F.
DESCR U TION OF THE PREFERRED EMBODIMENTS
The wet fines recycle process of the invention is applicable generally to a fluid coking process which com-prises a fluid coking zone and at least a second fluidized bed zone from which is removed a gaseous stream containing entrained coke fines. The second fluidized bed zone may be a heating zone, such as a combustion zone, for example, the fluidized bed of a conventional coke burner, or the second fluidized bed zone may be a heat exchange zone, or the second fluidized bed zone may be a gasification zone. The preferred embodiment will be described with reference to Figure 1.
Referring to Figure 1, a carbonaceous material having a Conradson carbon residue of about 15 weight percent, such as heavy residuum having a boiling point (at atmospheric pressure) of about 1,050F.+ is passed by line 10 into a coking zone 12 in which is maintained a fluidized bed of solids (e.g. coke particles of 40 to 1000 microns in size) having an upper level indicated at 14. Carbonaceous feeds suitable for the present 1nvention include heavy hydro-carbonaceous oils; heavy and reduced petroleum crudes;
petroleum atmospheric distillation bottoms; petroleum vacuum distillation bottoms; pitch, asphalt, bitumen, other heavy hydrocarbon residues; coal; coal slurry; liquid ~0 products derived from coal liquefaction processes, and mixtures thereof. Typically such feeds have a Conradson carbon resi-due of at least 5 weight percent, generally from about 5 :
~07~634 to about 50 weight percent, preferably above about 7 weight percent (as to Conradson carbon residue, see ASTM test D-189-65). A fluidizing gas, e.g. steam, is admitted at the base of coking reactor 1 through line 16 in an amount sufficient to obtain superficial fluidizing gas velocity in the range of 0.5 to 5 feet per second. Coke at a tem- -perature above the coking temperature, for example, at a temperature from about 100 to 800F. in excess of the actual operating temperature of the coking zone is admitted to reactor 1 by line 42 in an amount sufficient to maintain the coking temperature in the range of about 850 to about 1400F. The pressure in the coking zone is maintained in the range of about 0 to about 150 pounds per square inch gauge (psig)~ preferably in the range of about 5 to about 45 psig. The lower portion of the coking reactor serves as a stripping zone to remove occluded hydrocarbons from the coke. A stream of coke is withdrawn from the stripping zone by line lô and circula~ed to heater 2. Conversion products are passed through cyclone 20 to remove entrained ; 20 solids which are returned to the coking zone through dipleg 22. me vapors leave the cyclone through line 24 and pass into a scrubber 25 mounted on the coking reactor. If desired~ a stream of heavy material condensed in the scrub-ber may be recycled to the coking reactor via line 26. me coker conversion products are removed from scrubber 25 via line 28 for fractionation in a conventional manner. In heater 2~ stripped coke from coking reactor 1 (commonly called cold coke) is introduced by line 18 to a fluid bed of hot coke having an upper level indicated at 30. The bed is partially heated by passing a fuel gas into the heater by line 32. Supplementary heat is supplied to the heater by coke circulating in line 34. The gaseous effluent of , , . ' . . .......................................... .
: . .
the heater including entrained solids passes through a cyclone which nay be a first cyclone 36 and a second cyclone 38 wherein separation of the larger entrained solids occurs. The separated larger solids are returned to the heater bed via the respective cyclone diplegs. The heated gaseous effluent which still contains entrained solids fines is removed from heater 2 via line 40. The fines removal system will be subsequently described herein.
Hot coke is removed from the fluidized bed in heater 2 and recycled to coking reactor by line 42 to supply heat thereto. Another portion of coke is removed from heater 2 and passed by line 44 to a gasification zone 46 in gasifier 3 in which is maintained a bed of fluidized coke having a level indicated at 48. If desired, a purge stream of coke may be removed from heater 2 by line 50.
The gasification zone is maintained at a temper-ature ranging from about 1,600 to about 2,000F., and a pressure ranging from about 0 to about 150 psig~ preferably at a pressure ranging from about 10 to 60 psig~ and more preferably at a pressure ranging frum about 25 to about 45 psig. Steam by line 52 and an oxygen-containing gas such as air, commercial oxygen or air enriched with oxygen by line 54 are passed via line 56 into gasifier 3. Reaction of the coke particles in the gasification zone with the steam and the oxygen-containing gas produces a hydrogen and carbon monixide-containing fuel gas. The gasifier product fuel gas, which may further contain some entrained solids, is removed overhead from the gasifier 3 by line 32 and introduced into heater 2 to provide a portion of the required heat as previously described.
Nhile the process has been described for simplicity of description with respect to circulating coke as the fluidi~ed medium, it is to be understood that the fluldized seed particles on which the coke is deposited may be silica, alumina, zirconia, magnesia, calcium oxide, alundum, mullite, bauxite or the like. The fluidized solids may or may not be catalytic in nature.
Returning to line 40, the heater gaseous effluent containing entrained solids is passed via line 40, if desired, through an indirect heat exchanger 58 and then into a cyclone 60 in which a portion of the entrained solids is separated and removed from the cyclone as drg fines by line 62. A
gaseous hytrogen and carbon monixide-containlng stream including the remaining entrained solids is removed from cyclone 60 by line 64 and passed to a wet scrubber 66 such as, for example, a venturi scrubber, a packed bed, a wet cyclone or other conventional equipment, in which the solids-containing gas is scrubbed with a liquid introduced by line 68. The scrubbed fuel gas is recovered by line 69. The scrubbing liquid may be water, a water solution containing a chemical reactant or absorbing agent, or a hydrocarbon oil such as, for example, a gas oil. When water is used as the scrubbing liquid in the scrubber, at least a portion of the solids present in gaseous stream is separated from the gas to form, with the scrubbing water, a dilute solids-water slurry, which is removed from the scrubber by line 70.
Typically, the dilute slurry will contain about 1 to 10 weight percent solids. The dilute solids-water slurry is passed by line 70 to a water removal stage indicated at 72 wherein at least a portion of the water is removed from the dilute slurry to form a concentrated stream which may be a concentrated slurry or cake. The water removal may be conducted in several ways, for example, the dilute slurry may be concentrated by passage through a settling tank and/
.
~ - 7 -.
~070634 or the dilute slurry may be passed through a mechanical dewatering device such as a gravity belt filter press~ a centrifuge, a vacuum filter and the like. Whatever method of water removal may be used, a concentrated slurry or cake is formed which generally will contain from about 10 to about 50 or more weight percent solids. The concentrated slurry or cake is removed via line 74 ant passed to a concentration ad~ustment stage 76 in which the concentrated slurry or cake is mixed with a liquid to produce a slurry containing not more than about 30 weight percent solids, preferably not more than about 25 weight percent solids.
Suitable ranges of solids content in the slurry include from about 1 to about 30 weight percent solids, preferably from about S to about 25 weight percent solids, more prefer-ably from about 15 to about 25 weight percent solids. It should be noted that in the concentration ad~ustment stage, water may be used as the diluent or a hydrocarbon oil may be used instead of part or all of the water medium. Fur-thermore, as inticated above, a hydrocarbon oil may be used instead of water as scrubbing liquid in the scrubber.
The solids-liquid slurry of the proper concentration is then recycled to the coking reactor by line 78. Thus, the solids-liquid slurry recycled to the reactor may be a solids-water slurry, a solids-water-oil slurry or a solids-oil slurry.
In any case, it is critical that the concentration of solids in the slurry recycléd to the coking reactor be not greater than 30 weight percent, preferably not greater than 25 weight percent to be within a suitable viscosity rsnge to be pumpable and not to affect adversely process operation. When the slurry recycled to the coking zone ls a solids-water slurry, the concentration of solids in the slurry is preferably from about 10 to about 30 weight percent solids~ more preferably .
.
from about 15 to about 25 weight percent solids. When the slurry is a solids-in-oil slurry, the concentration of solids in the slurry is preferably from about 1 to 25 weight percent solids~ more preferably from about 5 to 15 weight percent solids. When the slurry is a solids-water-oil slurry, the concentration of solids in the slurry is preferably from about 5 to about 25 weight percent. The effect of solids concentration on viscosity at 76F. is shown in Figure 2.
As can be seen from the graph, above 20 weight percent solids, the viscosity increases very rapidly. At 26.2 weight percent solids, the viscosity exceeds 30,000 cp, whereas at 20 weight percent solids, the apparent viscosity is 200 cps. Increasing the temperature can reduce the viscosity. At 110F., the viscosity is reduced by a factor of 2 and at 160F., the viscosity is reduced by a factor of 4.
It is desirable to inject an inert gas such as nitrogen into the slurry carried by line 7O to atomize the slurry into the coking reactor. The nitrogen injection also serves to increase the velocity of the slurry in the line to the reactor thereby mini~izing plugging of the line.
Furthermore, the nitrogen reduces pressure drop in the system. The slurry may be injected into the coking reactor at a nozzle outlet velocity ranging from about 50 to about 300 feet per second, preferably from about 100 to about 200 feet per second.
It has now been found that gasification of the - gross coke product can be increased from about 95 to about 99% by recycling the coke or coke-coated fines recovered from the fuel gas product to the coking zone.
U.S. patent 3~414,504 discloses a fluid coking ` process in which a burner flue gas including entrained coke is combusted with air thereby producing heated dry coke particles which are recycled to the coker directly or in admixture with the oil feed. It should be noted that by the term llfluid coking process'l is intended herein a process which comprises a coking reactor and a burner vessel in which a portion of the coke product is burned to provide the heat requirements -of the process. Such a process is described in U.S. patent 2,881,130.
U.S. patent 3~278,412 discloses a process for fluid coking in which coke-coated tar sands fines recovered from a low temperature burner are burned to remove the coke therefrom and the coke-free fines are subsequently recycled to a coking zone.
:.
: ~, `~' 1070634 It has now been found that wet fines recovered from the gaseous effluent of a zone integrated with the coking zone can be advantageously recycled to the coking zone when the fines are recycled as a wet slurry of a specified concentra-tion, without adversely affecting the process operation in-cluding the particle size distribution of the fluidized solids.
Furthermore, in one embodiment of thé invention wherein the process is an integrated coking and gasification process, the recycled fines permit a higher level of gasification of the gross coke product than heretofore. Recycling the fines also eliminates the coke fines disposal problem.
SUMMARY OF THE INVENTIOM
In accordance with the invention, there is pro-vided in a coking process comprising the steps of:
(a) contacting a carbonaceous material under fluid coking conditions in a coking zone containing a first bed of fluidized solids to form coke, said coke depositing on said fluidized solids;
(b) introducing a portion of said solids with a coke deposition thereon to a second zone containing a second bed I of fluidized solids;
; (c) recovering from said second zone a gaseous stream containing entrained coke solids;
(d) sepa~rating at least a portion of said entrained coke solids from said gaseous stream; and (e) scrubbing the resulting gaseous stream con-taining entrained coke solids with a liquid to form a liquid-solids slurry, characterized by the steps which com-prise:
(f) adjusting the concentration of said liquid-~ 3-, /~
.
~070634 solids slurr~ such that said slurr~ comprises not more than 30 weight percent of said coke solids, based on said slurry, and . -(g) introducing the resulting slurry into said coking zone.
.
` -3a-`- ~07~634 BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic flow plan of one embodi-ment of the invention.
Figure 2 is a graph showing the effect of solids concentration on viscosity at 76F.
DESCR U TION OF THE PREFERRED EMBODIMENTS
The wet fines recycle process of the invention is applicable generally to a fluid coking process which com-prises a fluid coking zone and at least a second fluidized bed zone from which is removed a gaseous stream containing entrained coke fines. The second fluidized bed zone may be a heating zone, such as a combustion zone, for example, the fluidized bed of a conventional coke burner, or the second fluidized bed zone may be a heat exchange zone, or the second fluidized bed zone may be a gasification zone. The preferred embodiment will be described with reference to Figure 1.
Referring to Figure 1, a carbonaceous material having a Conradson carbon residue of about 15 weight percent, such as heavy residuum having a boiling point (at atmospheric pressure) of about 1,050F.+ is passed by line 10 into a coking zone 12 in which is maintained a fluidized bed of solids (e.g. coke particles of 40 to 1000 microns in size) having an upper level indicated at 14. Carbonaceous feeds suitable for the present 1nvention include heavy hydro-carbonaceous oils; heavy and reduced petroleum crudes;
petroleum atmospheric distillation bottoms; petroleum vacuum distillation bottoms; pitch, asphalt, bitumen, other heavy hydrocarbon residues; coal; coal slurry; liquid ~0 products derived from coal liquefaction processes, and mixtures thereof. Typically such feeds have a Conradson carbon resi-due of at least 5 weight percent, generally from about 5 :
~07~634 to about 50 weight percent, preferably above about 7 weight percent (as to Conradson carbon residue, see ASTM test D-189-65). A fluidizing gas, e.g. steam, is admitted at the base of coking reactor 1 through line 16 in an amount sufficient to obtain superficial fluidizing gas velocity in the range of 0.5 to 5 feet per second. Coke at a tem- -perature above the coking temperature, for example, at a temperature from about 100 to 800F. in excess of the actual operating temperature of the coking zone is admitted to reactor 1 by line 42 in an amount sufficient to maintain the coking temperature in the range of about 850 to about 1400F. The pressure in the coking zone is maintained in the range of about 0 to about 150 pounds per square inch gauge (psig)~ preferably in the range of about 5 to about 45 psig. The lower portion of the coking reactor serves as a stripping zone to remove occluded hydrocarbons from the coke. A stream of coke is withdrawn from the stripping zone by line lô and circula~ed to heater 2. Conversion products are passed through cyclone 20 to remove entrained ; 20 solids which are returned to the coking zone through dipleg 22. me vapors leave the cyclone through line 24 and pass into a scrubber 25 mounted on the coking reactor. If desired~ a stream of heavy material condensed in the scrub-ber may be recycled to the coking reactor via line 26. me coker conversion products are removed from scrubber 25 via line 28 for fractionation in a conventional manner. In heater 2~ stripped coke from coking reactor 1 (commonly called cold coke) is introduced by line 18 to a fluid bed of hot coke having an upper level indicated at 30. The bed is partially heated by passing a fuel gas into the heater by line 32. Supplementary heat is supplied to the heater by coke circulating in line 34. The gaseous effluent of , , . ' . . .......................................... .
: . .
the heater including entrained solids passes through a cyclone which nay be a first cyclone 36 and a second cyclone 38 wherein separation of the larger entrained solids occurs. The separated larger solids are returned to the heater bed via the respective cyclone diplegs. The heated gaseous effluent which still contains entrained solids fines is removed from heater 2 via line 40. The fines removal system will be subsequently described herein.
Hot coke is removed from the fluidized bed in heater 2 and recycled to coking reactor by line 42 to supply heat thereto. Another portion of coke is removed from heater 2 and passed by line 44 to a gasification zone 46 in gasifier 3 in which is maintained a bed of fluidized coke having a level indicated at 48. If desired, a purge stream of coke may be removed from heater 2 by line 50.
The gasification zone is maintained at a temper-ature ranging from about 1,600 to about 2,000F., and a pressure ranging from about 0 to about 150 psig~ preferably at a pressure ranging from about 10 to 60 psig~ and more preferably at a pressure ranging frum about 25 to about 45 psig. Steam by line 52 and an oxygen-containing gas such as air, commercial oxygen or air enriched with oxygen by line 54 are passed via line 56 into gasifier 3. Reaction of the coke particles in the gasification zone with the steam and the oxygen-containing gas produces a hydrogen and carbon monixide-containing fuel gas. The gasifier product fuel gas, which may further contain some entrained solids, is removed overhead from the gasifier 3 by line 32 and introduced into heater 2 to provide a portion of the required heat as previously described.
Nhile the process has been described for simplicity of description with respect to circulating coke as the fluidi~ed medium, it is to be understood that the fluldized seed particles on which the coke is deposited may be silica, alumina, zirconia, magnesia, calcium oxide, alundum, mullite, bauxite or the like. The fluidized solids may or may not be catalytic in nature.
Returning to line 40, the heater gaseous effluent containing entrained solids is passed via line 40, if desired, through an indirect heat exchanger 58 and then into a cyclone 60 in which a portion of the entrained solids is separated and removed from the cyclone as drg fines by line 62. A
gaseous hytrogen and carbon monixide-containlng stream including the remaining entrained solids is removed from cyclone 60 by line 64 and passed to a wet scrubber 66 such as, for example, a venturi scrubber, a packed bed, a wet cyclone or other conventional equipment, in which the solids-containing gas is scrubbed with a liquid introduced by line 68. The scrubbed fuel gas is recovered by line 69. The scrubbing liquid may be water, a water solution containing a chemical reactant or absorbing agent, or a hydrocarbon oil such as, for example, a gas oil. When water is used as the scrubbing liquid in the scrubber, at least a portion of the solids present in gaseous stream is separated from the gas to form, with the scrubbing water, a dilute solids-water slurry, which is removed from the scrubber by line 70.
Typically, the dilute slurry will contain about 1 to 10 weight percent solids. The dilute solids-water slurry is passed by line 70 to a water removal stage indicated at 72 wherein at least a portion of the water is removed from the dilute slurry to form a concentrated stream which may be a concentrated slurry or cake. The water removal may be conducted in several ways, for example, the dilute slurry may be concentrated by passage through a settling tank and/
.
~ - 7 -.
~070634 or the dilute slurry may be passed through a mechanical dewatering device such as a gravity belt filter press~ a centrifuge, a vacuum filter and the like. Whatever method of water removal may be used, a concentrated slurry or cake is formed which generally will contain from about 10 to about 50 or more weight percent solids. The concentrated slurry or cake is removed via line 74 ant passed to a concentration ad~ustment stage 76 in which the concentrated slurry or cake is mixed with a liquid to produce a slurry containing not more than about 30 weight percent solids, preferably not more than about 25 weight percent solids.
Suitable ranges of solids content in the slurry include from about 1 to about 30 weight percent solids, preferably from about S to about 25 weight percent solids, more prefer-ably from about 15 to about 25 weight percent solids. It should be noted that in the concentration ad~ustment stage, water may be used as the diluent or a hydrocarbon oil may be used instead of part or all of the water medium. Fur-thermore, as inticated above, a hydrocarbon oil may be used instead of water as scrubbing liquid in the scrubber.
The solids-liquid slurry of the proper concentration is then recycled to the coking reactor by line 78. Thus, the solids-liquid slurry recycled to the reactor may be a solids-water slurry, a solids-water-oil slurry or a solids-oil slurry.
In any case, it is critical that the concentration of solids in the slurry recycléd to the coking reactor be not greater than 30 weight percent, preferably not greater than 25 weight percent to be within a suitable viscosity rsnge to be pumpable and not to affect adversely process operation. When the slurry recycled to the coking zone ls a solids-water slurry, the concentration of solids in the slurry is preferably from about 10 to about 30 weight percent solids~ more preferably .
.
from about 15 to about 25 weight percent solids. When the slurry is a solids-in-oil slurry, the concentration of solids in the slurry is preferably from about 1 to 25 weight percent solids~ more preferably from about 5 to 15 weight percent solids. When the slurry is a solids-water-oil slurry, the concentration of solids in the slurry is preferably from about 5 to about 25 weight percent. The effect of solids concentration on viscosity at 76F. is shown in Figure 2.
As can be seen from the graph, above 20 weight percent solids, the viscosity increases very rapidly. At 26.2 weight percent solids, the viscosity exceeds 30,000 cp, whereas at 20 weight percent solids, the apparent viscosity is 200 cps. Increasing the temperature can reduce the viscosity. At 110F., the viscosity is reduced by a factor of 2 and at 160F., the viscosity is reduced by a factor of 4.
It is desirable to inject an inert gas such as nitrogen into the slurry carried by line 7O to atomize the slurry into the coking reactor. The nitrogen injection also serves to increase the velocity of the slurry in the line to the reactor thereby mini~izing plugging of the line.
Furthermore, the nitrogen reduces pressure drop in the system. The slurry may be injected into the coking reactor at a nozzle outlet velocity ranging from about 50 to about 300 feet per second, preferably from about 100 to about 200 feet per second.
Claims (17)
1. A coking process comprising the steps of:
(a) contacting a carbonaceous material under fluid coking conditions in a coking zone containing a first bed of fluidized solids to form coke, said coke depositing on said fluidized solids;
(b) introducing a portion of said solids with a coke deposition thereon to a second zone containing a second bed of fluidized solids;
(c) recovering from said second zone a gaseous stream containing entrained coke solids;
(d) separating at least a portion of said entrained coke solids from said gaseous stream; and (e) scrubbing the resulting gaseous stream containing entrained coke solids with a liquid to form a liquid-solids slurry, characterized by the steps which comprise:
(f) adjusting the concentration of said liquid-solids slurry such that said slurry comprises not more than 30 weight percent of said coke solids, based on said slurry, and (g) introducing the resulting slurry into said coking zone.
(a) contacting a carbonaceous material under fluid coking conditions in a coking zone containing a first bed of fluidized solids to form coke, said coke depositing on said fluidized solids;
(b) introducing a portion of said solids with a coke deposition thereon to a second zone containing a second bed of fluidized solids;
(c) recovering from said second zone a gaseous stream containing entrained coke solids;
(d) separating at least a portion of said entrained coke solids from said gaseous stream; and (e) scrubbing the resulting gaseous stream containing entrained coke solids with a liquid to form a liquid-solids slurry, characterized by the steps which comprise:
(f) adjusting the concentration of said liquid-solids slurry such that said slurry comprises not more than 30 weight percent of said coke solids, based on said slurry, and (g) introducing the resulting slurry into said coking zone.
2. The process of Claim 1 wherein the slurry intro-duced into said coking zone comprises not more than about 25 weight percent of said coke solids of step (e).
3. The process of Claim 1 wherein the slurry introduced into said coking zone comprises from about 1 to about 30 weight percent of said coke solids of step (e).
4. The process of Claim 1 wherein the slurry introduced into said coking zone comprises from about 5 to about 25 weight percent of said coke solids of step (e).
5. The process of Claim 1 wherein the slurry introduced into said coking zone comprises from about 15 to about 25 weight percent solids.
6. The process of Claim 1 wherein said second zone is a combustion zone.
7. The process of Claim 1 wherein said second zone is a heat exchange zone.
8. The process of Claim 1 wherein said second zone is a gasification zone.
9. An integrated coking and gasification process for the production of coke and a gaseous stream containing hydrogen comprising the steps of:
(a) reacting a carbonaceous material having a Conrad-son carbon content of at least 5 weight percent, in a coking zone containing a bed of fluidized solids maintained at a temperature ranging from about 850 to about 1400°F. to form coke, said coke depositing on said fluidized solids;
(b) introducing a portion of said solids with a coke deposition thereon into a heating zone operated at a temperature greater than said coking zone temperature to heat said portion of said solids;
(c) reclycling a first portion of heated solids from said heating zone to said coking zone;
(d) introducing a second portion of said heated solids to a fluid bed gasification zone maintained at a temperature greater than the temperature of said heating zone;
(e) reacting with said second portion of heated solids in a gasification zone with steam and oxygen-containing gas to produce a hot gaseous stream containing hydrogen;
(f) introducing said hot gaseous stream containing hydrogen and entrained solids into said heating zone;
(g) passing an additional stream of solids from the gasification zone to said heating zone;
(h) recovering from said heating zone the resulting cooled gaseous stream containing hydrogen and entrained coke solids, (i) separating at least a portion of said entrained coke solids from said gaseous stream, and (j) scrubbing the resulting gaseous stream containing entrained coke solids with a liquid to form a liquid-solids slurry, characterized by the steps which comprise:
(k) adjusting the concentration of said liquid-solids slurry such that said slurry comprises not more than about 30 weight percent of said coke solids, based on said slurry, and (l) introducing the resulting slurry into said coking zone.
(a) reacting a carbonaceous material having a Conrad-son carbon content of at least 5 weight percent, in a coking zone containing a bed of fluidized solids maintained at a temperature ranging from about 850 to about 1400°F. to form coke, said coke depositing on said fluidized solids;
(b) introducing a portion of said solids with a coke deposition thereon into a heating zone operated at a temperature greater than said coking zone temperature to heat said portion of said solids;
(c) reclycling a first portion of heated solids from said heating zone to said coking zone;
(d) introducing a second portion of said heated solids to a fluid bed gasification zone maintained at a temperature greater than the temperature of said heating zone;
(e) reacting with said second portion of heated solids in a gasification zone with steam and oxygen-containing gas to produce a hot gaseous stream containing hydrogen;
(f) introducing said hot gaseous stream containing hydrogen and entrained solids into said heating zone;
(g) passing an additional stream of solids from the gasification zone to said heating zone;
(h) recovering from said heating zone the resulting cooled gaseous stream containing hydrogen and entrained coke solids, (i) separating at least a portion of said entrained coke solids from said gaseous stream, and (j) scrubbing the resulting gaseous stream containing entrained coke solids with a liquid to form a liquid-solids slurry, characterized by the steps which comprise:
(k) adjusting the concentration of said liquid-solids slurry such that said slurry comprises not more than about 30 weight percent of said coke solids, based on said slurry, and (l) introducing the resulting slurry into said coking zone.
10. The process of Claim 9 wherein the slurry intro-duced into said coking zone comprises not more than about 25 weight percent (based on the slurry) of said coke solids.
11. The process of Claim 9 wherein the slurry intro-duced into said coking zone comprises from about 1 to about 30 weight percent (based on the slurry) of said coke solids.
12. The process of Claim 9 wherein the slurry intro-duced into said coking zone comprises from about 15 to about 25 weight percent (based on the slurry) of said coke solids.
13. The process of Claim 9 wherein said entrained solids are separated from said gaseous stream by scrubbing said gaseous stream with water to remove at least a portion of said entrained solids from said gaseous stream and thereby forming a dilute slurry of said separated solids in water, further characterized by the steps which comprise removing at least a portion of the water from said slurry to form a concentrated stream of solids-in-water, adjusting the concentration of said solids in water to form a slurry comprising from about 5 to about 30 weight percent solids, and introducing the resulting slurry into said coking zone.
14. The process of Claim 9 wherein said entrained solids are separated from said gaseous stream by scrubbing said gaseous stream with water to remove at least a portion of said entrained solids from said gaseous stream and thereby forming a dilute slurry of said separated solids in water, further charac-terized by the stemps which comprise removing at least a portion of said water from said dilute slurry to form a concentrated stream of solids-in-water, said concentrated stream comprising from about 10 to about 50 weight percent solids, mixing said concentrated stream with a hydrocarbon oil to produce a solids-water-oil mixture comprising from about 5 to about 25 weight percent solids, and introducing the resulting mixture into said coking zone.
15. The process of Claim 9 wherein said entrained solids are separated from said gaseous stream with a liquid, further characterized by the steps which comprises scrubbing the gaseous stream with a hydrocarbon oil to remove at least a portion of said solids from said gaseous stream and to form thereby a slurry of solids-in-oil, adjusting the content of said solids-in-oil to form a slurry comprising from about 1 to about 30 weight percent solids-in-oil, and introducing the resulting solids-in-oil slurry into said coking zone.
16. The process of Claim 15 wherein the solids-in-oil slurry introduced into said coking zone comprises from about 1 to about 25 weight percent solids.
17. The process of Claim 15 wherein the solids-in-oil slurry introduced into said coking zone comprises from about 5 to about 15 weight percent solids.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US62662275A | 1975-10-29 | 1975-10-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1070634A true CA1070634A (en) | 1980-01-29 |
Family
ID=24511154
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA251,500A Expired CA1070634A (en) | 1975-10-29 | 1976-04-30 | Fines recycle in a coking process |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS5254705A (en) |
| CA (1) | CA1070634A (en) |
| MX (1) | MX3879E (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4366048A (en) | 1981-07-09 | 1982-12-28 | Exxon Research And Engineering Co. | Fluid coking with the addition of solids |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2025453B (en) * | 1978-07-12 | 1982-07-07 | Texaco Development Corp | Recovery of ungasified solid fuel particles from suspension in water |
| US4331529A (en) * | 1980-11-05 | 1982-05-25 | Exxon Research & Engineering Co. | Fluid coking and gasification process |
| US4552649A (en) * | 1985-03-15 | 1985-11-12 | Exxon Research And Engineering Co. | Fluid coking with quench elutriation using industrial sludge |
-
1976
- 1976-04-30 CA CA251,500A patent/CA1070634A/en not_active Expired
- 1976-05-11 JP JP5289576A patent/JPS5254705A/en active Pending
- 1976-05-11 MX MX823776U patent/MX3879E/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4366048A (en) | 1981-07-09 | 1982-12-28 | Exxon Research And Engineering Co. | Fluid coking with the addition of solids |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5254705A (en) | 1977-05-04 |
| MX3879E (en) | 1981-08-26 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |