CA2151893A1 - Apparatus for separating solid particles from a gas and for injecting the so-separated particles into a reaction vessel - Google Patents
Apparatus for separating solid particles from a gas and for injecting the so-separated particles into a reaction vesselInfo
- Publication number
- CA2151893A1 CA2151893A1 CA002151893A CA2151893A CA2151893A1 CA 2151893 A1 CA2151893 A1 CA 2151893A1 CA 002151893 A CA002151893 A CA 002151893A CA 2151893 A CA2151893 A CA 2151893A CA 2151893 A1 CA2151893 A1 CA 2151893A1
- Authority
- CA
- Canada
- Prior art keywords
- discharge conduit
- fluidized bed
- combination
- solid particles
- reactor vessel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J4/00—Feed or outlet devices; Feed or outlet control devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D45/00—Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces
- B01D45/12—Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces by centrifugal forces
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/005—Separating solid material from the gas/liquid stream
- B01J8/0055—Separating solid material from the gas/liquid stream using cyclones
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
- B04C5/00—Apparatus in which the axial direction of the vortex is reversed
- B04C5/14—Construction of the underflow ducting; Apex constructions; Discharge arrangements ; discharge through sidewall provided with a few slits or perforations
- B04C5/18—Construction of the underflow ducting; Apex constructions; Discharge arrangements ; discharge through sidewall provided with a few slits or perforations with auxiliary fluid assisting discharge
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- 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
- C10J3/46—Gasification of granular or pulverulent flues in suspension
- C10J3/54—Gasification of granular or pulverulent fuels by the Winkler technique, i.e. by fluidisation
- C10J3/56—Apparatus; Plants
Abstract
An apparatus for separating solid particles contained in a flow of gaseous products and for injecting the separated particles into a reactor vessel.
This apparatus has a cyclone separator provided with a tangential entry port through which the flow of gaseous products is fed, an axial exhaust conduit through which the gaseous products fed into the separator exit from the same, a collection hopper in which fall the solid particles separated from the gaseous products by centrifugation and gravity within the separator, and a discharge conduit having an inlet within the collection hopper and an outlet opening into the reactor vessel.
It also has a gas injector for injecting a gas stream into the discharge conduit so as to cause the solid particles falling into the collection hopper to flow continuously out of the hopper through the discharge conduit and be fed into the reaction vessel in spite of any pressure differential that may exist between the collection hopper and the reactor vessel. This apparatus is typically used in combination with and within a fluidized bed reactor for the gasification of carbona-ceous solids. The incorporation of this apparatus permits to achieve a high efficiency of separation as a result of a high velocity of entry of the gaseous products to the cyclone separator and the continuous removal of the solid particles from the collection hopper of the cyclone separator through the discharge conduit, which advantageously penetrates deeply into the fluidized bed.
This apparatus has a cyclone separator provided with a tangential entry port through which the flow of gaseous products is fed, an axial exhaust conduit through which the gaseous products fed into the separator exit from the same, a collection hopper in which fall the solid particles separated from the gaseous products by centrifugation and gravity within the separator, and a discharge conduit having an inlet within the collection hopper and an outlet opening into the reactor vessel.
It also has a gas injector for injecting a gas stream into the discharge conduit so as to cause the solid particles falling into the collection hopper to flow continuously out of the hopper through the discharge conduit and be fed into the reaction vessel in spite of any pressure differential that may exist between the collection hopper and the reactor vessel. This apparatus is typically used in combination with and within a fluidized bed reactor for the gasification of carbona-ceous solids. The incorporation of this apparatus permits to achieve a high efficiency of separation as a result of a high velocity of entry of the gaseous products to the cyclone separator and the continuous removal of the solid particles from the collection hopper of the cyclone separator through the discharge conduit, which advantageously penetrates deeply into the fluidized bed.
Description
~ APPARATUS FOR SEPARATING SOLID PARTICLES
FROH A GAS AND FOR INJECTING THE SO-SEPARATED
PARTICLES INTO A REACTION VESSEL
PArK~-~UND OF THE INVENTION
Field of the Invention The present invention relates to an apparatus for separating solid particles from a flow of gaseous products and for injecting the so-separated particles into a reaction vessel in spite of a higher pressure that may exist therein.
The invention also relates to the combination of such an apparatus with a fluidized bed reactor as used for the gasification of carboneous materials, in order to achieve a higher degree of conversion of carbon into a fuel gas.
Brief Description of the prior art It is known that the gasification of carbonaceous materials, such as coal or biomass, in a fluidized bed reactor releases solid particles mixed with a combustible gaseous product. These solid particles generally known as "char", contain a large amount of partially reacted carbonaceous materials, in addition to ash originating from the feed material and from the inert fluidizing medium.
In order to enhance the degree of gasification of the solid feed material and to minimize particulate concen-tration in the gaseous product, it is necessary to separate any solid particles entrained from the fluid bed from the stream of gaseous products. The particles which are separated, can then be re-injected into the fluidized bed reactor, so as to cause reaction of the carbon bearing compounds containing therein with the _ fluidizing gases, and thus produce additional combustible gases.
As aforesaid, the solid particles carried by the gaseous stream removed from the fluidized bed reactor also contain mineral matter such as ash from the feed materials, inert particles from the fluidizing medium, or some of the catalyst introduced in the bed to enhance the rate of reaction.
The separation of such solid particles from the flow of gaseous products is currently achieved by means of one or more cyclone separator(s) incorporated into the gas discharge conduit of the reactor. The cyclone separators are usually installed outside of, and separate from, the reactor vessel and connected to the discharge conduit for the gaseous products. It is also necessary, for practical reasons, to operate the cyclone separators at a gas pressure which is somewhat lower than that in the gasification reactor. The solids removed from the gases in such separators, are subsequently fed back to the fluidized bed reactor by mechanical means such as a screw feeder or star valve, designed to prevent the back flow of gases from the reactor vessel to the separator, which flow would impair its operation.
In order to eliminate the expense of an addi-tional pressure vessel and of connecting conduits, attempts have been made to mount the cyclone separator(s) inside and at the top of the fluidized bed reactor vessel. Such is currently the practice in fluid bed catalytic crackers for petroleum products. However, experience has shown this to be impractical for the separation of char in the discharge conduit of gasification reactors. The operation of a high efficiency cyclone separator at a high pressure drop, together with the requirement for injection of the char deep in the fluidized bed, causes a subStantial pressure .
dlfference between the body of the cyclone separator and the point of discharge of the char in the fluidized bed.
Pneumatic devices such as "L" valves mounted in the solids discharge conduit or "dipleg" of the separator do not provide adequate sealing against the backflow of gases. Moreover, mechanical sealing devices such as flapper valves, star valves or screw feeders require extensive and frequent attention when operating under severe conditions of corrosion and temperature.
Such attention cannot practically be provided inside a fluidized bed reactor without prolonged interruption of the operation.
Consequently, the present practice is to effect the separation of the solid particles from the discharge gases of fluid bed gasification reactors, in one or more cyclone separators mounted externally to the reactor vessel, as was mentioned hereinabove. The solid particles removed from such separators are then cooled under an oxygen free atmosphere to prevent overheating and fusion of the ash, and fed to the body of the fluidized bed reactor by means of mechanical sealing and feeding devices. The mechanical complexity of this system increases equipment and maintenance costs, while causing losses in carbon and thermal efficiency.
OBJECT OF THE INVENTION
- The object of the present invention is to provide an apparatus which can be used in combination with a fluidized bed chemical reactor like that used for the gasification of carbonaceous materials, which apparatus improves the separation of the solid particles suspended in the gaseous products and allows the injection into the fluidized bed, thereby resulting in a virtual completion of the chemical reaction with a simultaneous reduction of the mechanical and operational complexities of the current method.
~ 2151893 Another object of the invention is to enhance the production of fuel gas in a fluidized bed reactor by means of an apparatus, which improves the separation efficiency of solid particles from the flow of gaseous product of the gasification reaction and allows for the injection of the so removed solid particles together with a portion of the gaseous products as a continuous stream deep into the fluidized bed, near the point of entry of the fluidizing gas such as to cause the rapid volatilization of the carbonaceous solids together with the release of heat as required for the gasification of the feed material.
SUMMARY OF THE INVENTION
In accordance with the present invention, the above object is achieved with an apparatus for separating solid particles contained in a flow of gaseous products and for injecting the separated particles into a reactor vessel, the apparatus comprising:
(a) a cyclone separator having:
at least one tangential entry port through which said flow of gaseous products is fed, an axial exhaust conduit through which the gaseous products fed into the separator exit from the same;
a collection hopper into which fall solid particles separated from the gaseous products are directed by centrifugation and gravity within the separator, and a discharge conduit having an inlet within said collection hopper and an outlet opening into the reactor vessel;
(b) a gas injector for injecting a gas stream into said discharge conduit so as to cause the solid particles falling into the collection hopper to flow continuously out of said hopper through said discharge conduit and be fed into the reaction vessel in spite of any pressure diffe-rential that may exist between the collection hopper and the reactor vessel.
The apparatus is preferably used in combination with and within a fluidized bed reactor, on the top of which it is preferably mounted when the fluidized bed reactor is used as a chemical reactor.
The incorporation of this apparatus permits to achieve a high efficiency of separation thanks to a high velocity of entry of the gaseous products to the cyclone separator and the continuous removal of the solid particles from the collection hopper of the cyclone separator through the discharge conduit which advantageously penetrates deeply into the fluidized bed.
As aforesaid, the flow of solid particles out of the cyclone separators is driven by means of the gas injector mounted in the discharge conduit, which opposes the pressure difference in the other direction between the fluid bed and the body of the cyclone separator.
If desired, two or more cyclone separators can be used, whether in series or in parallel, within or outside of the reactor vessel. In such a case the discharge conduit of each separator is equipped with a gas injector to discharge the solid particles and gases deep into the fluidized bed.
When applied to the gasification of carbonaceous materials, the apparatus of the present invention can achieve the conversion of the carbon contained in the carboneous feed solids nearly to completion, in a single pressure vessel, without the mechanical complexity of external cooling and re-injection devices used so far. Such a high carbon conversion is achieved by the combined effect of a high separation efficiency in the cyclone separator(s) and of the high reactivity of the nascent char re-injected together with steam, in the oxidation zone of the fluidized bed reactor, near the point of entry of the fluidizing gases.
The present invention could also be applied to enhance any other fluidized bed chemical process such as combustion. For example, in a circulating fluidizing bed process, a high capacity cyclone separator according to the transport invention could be mounted within or outside the transport reactor vessel.
BRIEF DESCRIPTION OF THE DRAWINGS
The structure, advantages and applications of the invention will be better understood upon reading the following, non restrictive description of preferred embodiments thereof, made with reference to the accompanying drawings wherein:
Figure 1 is a schematic elevational view in cross-section of a fluidized bed gasification apparatus provided with a cyclone separator internally mounted therein and equipped with a gas injector in its dipleg, as is called for in accordance with the invention;
Figure lA is a cross-sectional view of the apparatus shown in Figure 1, taken along line A-A of this figure;
Figure 2 is a schematic cross-sectional view of the cyclone separator shown in Figure 1, which incorporates a steam injector in its dipleg;
Figure 3 is a schematic cross-sectional view of another fluidized bed gasification apparatus provided with two cyclone separators in series both of which are equipped with a steam injector, as is called for in accordance with the present invention; and Figure 3A is an enlarged view of the outlet of one of the dipleg of the separators shown in Figure 3.
DESCRIPTION OF PREFERRED ENBODIMENTS
`- 2151893 ~ Referring to Figure 1, there is shown a first preferred embodiment of the invention, comprising a vertically extending, cylindrical pressure vessel 10 acting as a fluidized bed gasification reactor.
Granulated carbonaceous material to be gasified, such as biomass, is fed through an inlet 12 into the vessel 10 while an oxygen containing gas such as air is fed through an inlet 1~ to a plenum chamber 14 located at the bottom of the vessel and this to the latter through a fluidizing orifice plate 15.
A fluidizing medium in the form of inert particles such as sand, i5 maintained as a fluid bed 16 by the upward flow of gas in the bottom section of the vessel 10. The feed material reacts with the fluidizing gas in the fluid bed at high temperature and is rapidly dried and volatilized to yield a char and product gases.
The gaseous products from the reaction rises through the bed surface 16 to the reaction zone 17 of the vessel while carrying, in suspension, fine particles of char, ash and ~and from the bed.
The stream of gaseous products flow through tan-gential entry ports 18 into the body of a cyclone separator 19, wherein the particles suspended in the gaseous products are separated by centrifugal forces and carried by gravity forces aided by a small flow of gas to a collection hopper 20, while the larger part of the gaseous product exits through an axial exhaust conduit 21 located at the top center of the cyclone separator, substantially free of solid particles. A small portion (5 to 10%) of the gaseous products flowing into the separator 19 is allowed to flow down through the collection hopper 20 and to exit, together with the separated particles, via a discharge conduit 22, known as a "dipleg", into the bottom zone of the fluid bed close to the fluidizing orifice plate 15. The downward flow of gaseous products and particles in the dipleg 22 is sustained against the opposing difference in pressure existing between the discharge point in the fluid bed 16, and the body of the cyclone separator 19, by virtue of the momentum of a jet of a high pressure gas preferably consisting of steam, that is injected in a throat at the entrance of the dipleg 22, by means of a nozzle 25' fed by a gas supply line 25 installed inside the axial exhaust conduit 21. Advantageously, the gas which is so supplied is steam.
An overflow pipe 23 connected to a shut off valve 24 provides for the periodic removal of excess solids accumulated in the fluid bed as a result of the continuous addition of ash by the solid feed materials.
As can be appreciated, the char together with the gaseous products and steam discharged from the dipleg 22 are well mixed with the fluidizing gas and sand in the bottom zone of the bed. The hot and reactive char that is so recycled is thus brought into contact with the flui-dizing gas prior to its contact with the feed material entering in the middle and top zones of the bed. As a result, the char can react preferentially with the oxygen in the fluidizing gas, causing its rapid and complete gasification together with the liberation of heat which serves to maintain the temperature necessary for the gasification reaction.
The steam brought in with the char provides a necessary cooling effect through the water gas reaction and the temperature in this zone is thus held at a safe level, below the ash fusion point. In this connection, one may appreciate that the temperature in this zone could effectively be regulated by a control device 42 for adjusting the flow rate of the steam.
The heat released by the reaction in this lower zone of the fluidized bed is also transferred to the sand and fluidizing gas and contributes to the process require-ments in the middle and upper zones of the bed where the solid feed material reacts with the fluidizing gases.
The larger particles of the carbonaceous feed materials remain in the bed until they are sufficiently reduced in size to be carried upwards by the gases flowing out of the free surface of the bed 16 into the reaction zone 17, and into the cyclone separator 19.
The amount and size of the particles carried upward into the reaction zone depend on the velocity of the gases and on the pressure and temperature within the zone.
Thus, the invention provides an effective means for collecting and re-injecting the char deep into the bed, thereby permitting substantially higher gas velocities and flows of char out of the bed than in the existing processes. This, in turn, allows for a larqer portion of the heat produced during the process to be obtained by combustion of the char in the bed.
In addition, a higher concentration of char and other solids in the reaction zone over the bed, favors the cracking of tars and higher hydrocarbons, and thus improves the cold gas efficiency of the process.
Referring now to figure 2, there is shown an enlarged cross-section view of the cyclone separator 19 shown in figure 1 equipped with a collection hopper and a built-in gas injector device according to this invention.
As outlined above, the cylindrical body of the cyclone separator 19 is equipped on top with one or two tangentially mounted entry parts 18, through which the particle-loaded gaseous products are introduced at high `
velocity, causing a cyclonic, rotary and downwards motion of the gases in the body of the separator, moving downwards and the separation by centrifugal forces of the solid particles as in any conventional cyclone separator.
The solid particles separated from the gaseous products drop into the collection hopper 20 mounted at the bottom end of the cyclone separator, and are subsequently discharged through the dipleg 22 to the bottom zone of the fluid bed.
In order to insure an uninterrupted flow of the particles out of the cyclone separator, it is necessary to induce the flow of a small amount of gas together with the particles, out of the bottom of the separator.
As aforesaid, in accordance with the invention, this flow of gas is obtained by incorporating a steam injector 25' within the separator body adjacent the throat-shaped inlet of the dipleg 22. By means of the steam jet 24 generated by the injector 25', a flow of gas and particles is induced downwardly into the dipleg 22 and discharged into the fluid bed.
The provision of such steam jet at the top of dipleg 22 of the cyclone separator 19 provide a pressure increase in the dipleg which opposes any back pressure from the body of the fluidized bed. This permits the velocity of entry to the cyclone separator and its efficiency to be raised at will, without concern for any return flow up the dipleg 22, which would inevitably spoil the operation of the cyclone separator.
Referring now to figure 3, there is shown another preferred embodiment of this invention wherein two cyclone separators 26 and 28 are installed in series in a reactor vessel similar to the one referred to ` -- hereinabove, in order to improve the efficiency of separation of particles. The gaseous products evolved from the fluidizing bed are introduced into the first cyclone unit 26, from which they are led by a conduit 27 to a second cyclone unit 28, in which additional solid particles are removed. The gaseous products leaving the second separator 28 are fihally discharged through a conduit 29. Each cyclone separator or unit is equipped with a collection hopper 30 and 31 and with a steam injector 32 and 33 as was disclosed herein-above. Steam supplied by a line 34 is fed to the nozzle of each injector and the particles collected together with the entrained gases and steam are discharged in the bottom zone of the fluid bed through diplegs 35 and 36.
In this embodiment as well as in the other one previously described, each dipleg is preferably equipped with a diffuser section 37 and 38 which has an outlet at the bottom end, which, together with diffusing cones 39 and 40 mounted on the orifice plate 41, insure an even dispersion of the released streams and particles and an adequate mixing of the same with the fluidizing gas and medium.
EXAMPLE
A carbonaceous material consisting of chipped wood, was fluidized in a bed of sand under a pressure of 1 to 30 atmospheres at a temperature of 1400 to 2000 F, in a cylindrical vertically mounted, refractory lined pressure reactor vessel. A high efficiency cyclone separator according to the invention was mounted inside the reactor vessel, at its top. The gaseous products were admitted directly into the separator, while the clean gases were discharged by a conduit through the top of the pressure vessel.
The separated solid particles were discharged from the conical bottom of the cyclone separator through a dipleg together with a fraction of about 3 to 10% of the gases, and re-injected deep in the fluidized bed at the bottom of the vessel. The pressure in the fluid bed being higher than in the body of the cyclone, it was necessary to provide a downward driving force for the gases and solids in the dipleg. Such a necessary driving force was supplied by means of a gas injector mounted in the dipleg, in which a jet of high pressure steam entrained the gases and the solid particles into the fluid bed.
Upon their entry into the lower zone of the fluidized bed, the char, the gases and steam were brought into contact with the fluidizing air, causing a rapid reaction while the steam served to enhance the reaction and prevent overheating of the fluid bed in that zone and the risk of fusion of the ashes.
It will be understood that the invention and its operation and applications are not limited to the two embo-diments described hereinabove or to the shape and forms shown in the drawings. As a matter of fact, the invention is applicable to any cyclone separators or combination of separators, wherein the separated solids have to be discharged against a back pressure.
FROH A GAS AND FOR INJECTING THE SO-SEPARATED
PARTICLES INTO A REACTION VESSEL
PArK~-~UND OF THE INVENTION
Field of the Invention The present invention relates to an apparatus for separating solid particles from a flow of gaseous products and for injecting the so-separated particles into a reaction vessel in spite of a higher pressure that may exist therein.
The invention also relates to the combination of such an apparatus with a fluidized bed reactor as used for the gasification of carboneous materials, in order to achieve a higher degree of conversion of carbon into a fuel gas.
Brief Description of the prior art It is known that the gasification of carbonaceous materials, such as coal or biomass, in a fluidized bed reactor releases solid particles mixed with a combustible gaseous product. These solid particles generally known as "char", contain a large amount of partially reacted carbonaceous materials, in addition to ash originating from the feed material and from the inert fluidizing medium.
In order to enhance the degree of gasification of the solid feed material and to minimize particulate concen-tration in the gaseous product, it is necessary to separate any solid particles entrained from the fluid bed from the stream of gaseous products. The particles which are separated, can then be re-injected into the fluidized bed reactor, so as to cause reaction of the carbon bearing compounds containing therein with the _ fluidizing gases, and thus produce additional combustible gases.
As aforesaid, the solid particles carried by the gaseous stream removed from the fluidized bed reactor also contain mineral matter such as ash from the feed materials, inert particles from the fluidizing medium, or some of the catalyst introduced in the bed to enhance the rate of reaction.
The separation of such solid particles from the flow of gaseous products is currently achieved by means of one or more cyclone separator(s) incorporated into the gas discharge conduit of the reactor. The cyclone separators are usually installed outside of, and separate from, the reactor vessel and connected to the discharge conduit for the gaseous products. It is also necessary, for practical reasons, to operate the cyclone separators at a gas pressure which is somewhat lower than that in the gasification reactor. The solids removed from the gases in such separators, are subsequently fed back to the fluidized bed reactor by mechanical means such as a screw feeder or star valve, designed to prevent the back flow of gases from the reactor vessel to the separator, which flow would impair its operation.
In order to eliminate the expense of an addi-tional pressure vessel and of connecting conduits, attempts have been made to mount the cyclone separator(s) inside and at the top of the fluidized bed reactor vessel. Such is currently the practice in fluid bed catalytic crackers for petroleum products. However, experience has shown this to be impractical for the separation of char in the discharge conduit of gasification reactors. The operation of a high efficiency cyclone separator at a high pressure drop, together with the requirement for injection of the char deep in the fluidized bed, causes a subStantial pressure .
dlfference between the body of the cyclone separator and the point of discharge of the char in the fluidized bed.
Pneumatic devices such as "L" valves mounted in the solids discharge conduit or "dipleg" of the separator do not provide adequate sealing against the backflow of gases. Moreover, mechanical sealing devices such as flapper valves, star valves or screw feeders require extensive and frequent attention when operating under severe conditions of corrosion and temperature.
Such attention cannot practically be provided inside a fluidized bed reactor without prolonged interruption of the operation.
Consequently, the present practice is to effect the separation of the solid particles from the discharge gases of fluid bed gasification reactors, in one or more cyclone separators mounted externally to the reactor vessel, as was mentioned hereinabove. The solid particles removed from such separators are then cooled under an oxygen free atmosphere to prevent overheating and fusion of the ash, and fed to the body of the fluidized bed reactor by means of mechanical sealing and feeding devices. The mechanical complexity of this system increases equipment and maintenance costs, while causing losses in carbon and thermal efficiency.
OBJECT OF THE INVENTION
- The object of the present invention is to provide an apparatus which can be used in combination with a fluidized bed chemical reactor like that used for the gasification of carbonaceous materials, which apparatus improves the separation of the solid particles suspended in the gaseous products and allows the injection into the fluidized bed, thereby resulting in a virtual completion of the chemical reaction with a simultaneous reduction of the mechanical and operational complexities of the current method.
~ 2151893 Another object of the invention is to enhance the production of fuel gas in a fluidized bed reactor by means of an apparatus, which improves the separation efficiency of solid particles from the flow of gaseous product of the gasification reaction and allows for the injection of the so removed solid particles together with a portion of the gaseous products as a continuous stream deep into the fluidized bed, near the point of entry of the fluidizing gas such as to cause the rapid volatilization of the carbonaceous solids together with the release of heat as required for the gasification of the feed material.
SUMMARY OF THE INVENTION
In accordance with the present invention, the above object is achieved with an apparatus for separating solid particles contained in a flow of gaseous products and for injecting the separated particles into a reactor vessel, the apparatus comprising:
(a) a cyclone separator having:
at least one tangential entry port through which said flow of gaseous products is fed, an axial exhaust conduit through which the gaseous products fed into the separator exit from the same;
a collection hopper into which fall solid particles separated from the gaseous products are directed by centrifugation and gravity within the separator, and a discharge conduit having an inlet within said collection hopper and an outlet opening into the reactor vessel;
(b) a gas injector for injecting a gas stream into said discharge conduit so as to cause the solid particles falling into the collection hopper to flow continuously out of said hopper through said discharge conduit and be fed into the reaction vessel in spite of any pressure diffe-rential that may exist between the collection hopper and the reactor vessel.
The apparatus is preferably used in combination with and within a fluidized bed reactor, on the top of which it is preferably mounted when the fluidized bed reactor is used as a chemical reactor.
The incorporation of this apparatus permits to achieve a high efficiency of separation thanks to a high velocity of entry of the gaseous products to the cyclone separator and the continuous removal of the solid particles from the collection hopper of the cyclone separator through the discharge conduit which advantageously penetrates deeply into the fluidized bed.
As aforesaid, the flow of solid particles out of the cyclone separators is driven by means of the gas injector mounted in the discharge conduit, which opposes the pressure difference in the other direction between the fluid bed and the body of the cyclone separator.
If desired, two or more cyclone separators can be used, whether in series or in parallel, within or outside of the reactor vessel. In such a case the discharge conduit of each separator is equipped with a gas injector to discharge the solid particles and gases deep into the fluidized bed.
When applied to the gasification of carbonaceous materials, the apparatus of the present invention can achieve the conversion of the carbon contained in the carboneous feed solids nearly to completion, in a single pressure vessel, without the mechanical complexity of external cooling and re-injection devices used so far. Such a high carbon conversion is achieved by the combined effect of a high separation efficiency in the cyclone separator(s) and of the high reactivity of the nascent char re-injected together with steam, in the oxidation zone of the fluidized bed reactor, near the point of entry of the fluidizing gases.
The present invention could also be applied to enhance any other fluidized bed chemical process such as combustion. For example, in a circulating fluidizing bed process, a high capacity cyclone separator according to the transport invention could be mounted within or outside the transport reactor vessel.
BRIEF DESCRIPTION OF THE DRAWINGS
The structure, advantages and applications of the invention will be better understood upon reading the following, non restrictive description of preferred embodiments thereof, made with reference to the accompanying drawings wherein:
Figure 1 is a schematic elevational view in cross-section of a fluidized bed gasification apparatus provided with a cyclone separator internally mounted therein and equipped with a gas injector in its dipleg, as is called for in accordance with the invention;
Figure lA is a cross-sectional view of the apparatus shown in Figure 1, taken along line A-A of this figure;
Figure 2 is a schematic cross-sectional view of the cyclone separator shown in Figure 1, which incorporates a steam injector in its dipleg;
Figure 3 is a schematic cross-sectional view of another fluidized bed gasification apparatus provided with two cyclone separators in series both of which are equipped with a steam injector, as is called for in accordance with the present invention; and Figure 3A is an enlarged view of the outlet of one of the dipleg of the separators shown in Figure 3.
DESCRIPTION OF PREFERRED ENBODIMENTS
`- 2151893 ~ Referring to Figure 1, there is shown a first preferred embodiment of the invention, comprising a vertically extending, cylindrical pressure vessel 10 acting as a fluidized bed gasification reactor.
Granulated carbonaceous material to be gasified, such as biomass, is fed through an inlet 12 into the vessel 10 while an oxygen containing gas such as air is fed through an inlet 1~ to a plenum chamber 14 located at the bottom of the vessel and this to the latter through a fluidizing orifice plate 15.
A fluidizing medium in the form of inert particles such as sand, i5 maintained as a fluid bed 16 by the upward flow of gas in the bottom section of the vessel 10. The feed material reacts with the fluidizing gas in the fluid bed at high temperature and is rapidly dried and volatilized to yield a char and product gases.
The gaseous products from the reaction rises through the bed surface 16 to the reaction zone 17 of the vessel while carrying, in suspension, fine particles of char, ash and ~and from the bed.
The stream of gaseous products flow through tan-gential entry ports 18 into the body of a cyclone separator 19, wherein the particles suspended in the gaseous products are separated by centrifugal forces and carried by gravity forces aided by a small flow of gas to a collection hopper 20, while the larger part of the gaseous product exits through an axial exhaust conduit 21 located at the top center of the cyclone separator, substantially free of solid particles. A small portion (5 to 10%) of the gaseous products flowing into the separator 19 is allowed to flow down through the collection hopper 20 and to exit, together with the separated particles, via a discharge conduit 22, known as a "dipleg", into the bottom zone of the fluid bed close to the fluidizing orifice plate 15. The downward flow of gaseous products and particles in the dipleg 22 is sustained against the opposing difference in pressure existing between the discharge point in the fluid bed 16, and the body of the cyclone separator 19, by virtue of the momentum of a jet of a high pressure gas preferably consisting of steam, that is injected in a throat at the entrance of the dipleg 22, by means of a nozzle 25' fed by a gas supply line 25 installed inside the axial exhaust conduit 21. Advantageously, the gas which is so supplied is steam.
An overflow pipe 23 connected to a shut off valve 24 provides for the periodic removal of excess solids accumulated in the fluid bed as a result of the continuous addition of ash by the solid feed materials.
As can be appreciated, the char together with the gaseous products and steam discharged from the dipleg 22 are well mixed with the fluidizing gas and sand in the bottom zone of the bed. The hot and reactive char that is so recycled is thus brought into contact with the flui-dizing gas prior to its contact with the feed material entering in the middle and top zones of the bed. As a result, the char can react preferentially with the oxygen in the fluidizing gas, causing its rapid and complete gasification together with the liberation of heat which serves to maintain the temperature necessary for the gasification reaction.
The steam brought in with the char provides a necessary cooling effect through the water gas reaction and the temperature in this zone is thus held at a safe level, below the ash fusion point. In this connection, one may appreciate that the temperature in this zone could effectively be regulated by a control device 42 for adjusting the flow rate of the steam.
The heat released by the reaction in this lower zone of the fluidized bed is also transferred to the sand and fluidizing gas and contributes to the process require-ments in the middle and upper zones of the bed where the solid feed material reacts with the fluidizing gases.
The larger particles of the carbonaceous feed materials remain in the bed until they are sufficiently reduced in size to be carried upwards by the gases flowing out of the free surface of the bed 16 into the reaction zone 17, and into the cyclone separator 19.
The amount and size of the particles carried upward into the reaction zone depend on the velocity of the gases and on the pressure and temperature within the zone.
Thus, the invention provides an effective means for collecting and re-injecting the char deep into the bed, thereby permitting substantially higher gas velocities and flows of char out of the bed than in the existing processes. This, in turn, allows for a larqer portion of the heat produced during the process to be obtained by combustion of the char in the bed.
In addition, a higher concentration of char and other solids in the reaction zone over the bed, favors the cracking of tars and higher hydrocarbons, and thus improves the cold gas efficiency of the process.
Referring now to figure 2, there is shown an enlarged cross-section view of the cyclone separator 19 shown in figure 1 equipped with a collection hopper and a built-in gas injector device according to this invention.
As outlined above, the cylindrical body of the cyclone separator 19 is equipped on top with one or two tangentially mounted entry parts 18, through which the particle-loaded gaseous products are introduced at high `
velocity, causing a cyclonic, rotary and downwards motion of the gases in the body of the separator, moving downwards and the separation by centrifugal forces of the solid particles as in any conventional cyclone separator.
The solid particles separated from the gaseous products drop into the collection hopper 20 mounted at the bottom end of the cyclone separator, and are subsequently discharged through the dipleg 22 to the bottom zone of the fluid bed.
In order to insure an uninterrupted flow of the particles out of the cyclone separator, it is necessary to induce the flow of a small amount of gas together with the particles, out of the bottom of the separator.
As aforesaid, in accordance with the invention, this flow of gas is obtained by incorporating a steam injector 25' within the separator body adjacent the throat-shaped inlet of the dipleg 22. By means of the steam jet 24 generated by the injector 25', a flow of gas and particles is induced downwardly into the dipleg 22 and discharged into the fluid bed.
The provision of such steam jet at the top of dipleg 22 of the cyclone separator 19 provide a pressure increase in the dipleg which opposes any back pressure from the body of the fluidized bed. This permits the velocity of entry to the cyclone separator and its efficiency to be raised at will, without concern for any return flow up the dipleg 22, which would inevitably spoil the operation of the cyclone separator.
Referring now to figure 3, there is shown another preferred embodiment of this invention wherein two cyclone separators 26 and 28 are installed in series in a reactor vessel similar to the one referred to ` -- hereinabove, in order to improve the efficiency of separation of particles. The gaseous products evolved from the fluidizing bed are introduced into the first cyclone unit 26, from which they are led by a conduit 27 to a second cyclone unit 28, in which additional solid particles are removed. The gaseous products leaving the second separator 28 are fihally discharged through a conduit 29. Each cyclone separator or unit is equipped with a collection hopper 30 and 31 and with a steam injector 32 and 33 as was disclosed herein-above. Steam supplied by a line 34 is fed to the nozzle of each injector and the particles collected together with the entrained gases and steam are discharged in the bottom zone of the fluid bed through diplegs 35 and 36.
In this embodiment as well as in the other one previously described, each dipleg is preferably equipped with a diffuser section 37 and 38 which has an outlet at the bottom end, which, together with diffusing cones 39 and 40 mounted on the orifice plate 41, insure an even dispersion of the released streams and particles and an adequate mixing of the same with the fluidizing gas and medium.
EXAMPLE
A carbonaceous material consisting of chipped wood, was fluidized in a bed of sand under a pressure of 1 to 30 atmospheres at a temperature of 1400 to 2000 F, in a cylindrical vertically mounted, refractory lined pressure reactor vessel. A high efficiency cyclone separator according to the invention was mounted inside the reactor vessel, at its top. The gaseous products were admitted directly into the separator, while the clean gases were discharged by a conduit through the top of the pressure vessel.
The separated solid particles were discharged from the conical bottom of the cyclone separator through a dipleg together with a fraction of about 3 to 10% of the gases, and re-injected deep in the fluidized bed at the bottom of the vessel. The pressure in the fluid bed being higher than in the body of the cyclone, it was necessary to provide a downward driving force for the gases and solids in the dipleg. Such a necessary driving force was supplied by means of a gas injector mounted in the dipleg, in which a jet of high pressure steam entrained the gases and the solid particles into the fluid bed.
Upon their entry into the lower zone of the fluidized bed, the char, the gases and steam were brought into contact with the fluidizing air, causing a rapid reaction while the steam served to enhance the reaction and prevent overheating of the fluid bed in that zone and the risk of fusion of the ashes.
It will be understood that the invention and its operation and applications are not limited to the two embo-diments described hereinabove or to the shape and forms shown in the drawings. As a matter of fact, the invention is applicable to any cyclone separators or combination of separators, wherein the separated solids have to be discharged against a back pressure.
Claims (18)
1. An apparatus for separating solid particles contained in a flow of gaseous products and for injecting the particles into a reactor vessel, said apparatus comprising:
(a) a cyclone separator having:
at least one tangential entry port through which said flow of gaseous products is fed;
an axial exhaust conduit through which the gaseous products fed into the separator exit from the same;
a collection hopper into which fall the solid particles which are separated from the gaseous products by centrifugation and gravity within the separator, are directed a discharge conduit having an inlet within said collection hopper and an outlet opening into said reaction vessel; and (b) a gas injector for injecting a gas stream into said discharge conduit so as to cause the solid particles falling into the collection hopper to flow continuously out of said hopper through said discharge conduit and to be fed into said reactor vessel in spite of any pressure differential that may exist between said collection hopper and said reactor vessel.
(a) a cyclone separator having:
at least one tangential entry port through which said flow of gaseous products is fed;
an axial exhaust conduit through which the gaseous products fed into the separator exit from the same;
a collection hopper into which fall the solid particles which are separated from the gaseous products by centrifugation and gravity within the separator, are directed a discharge conduit having an inlet within said collection hopper and an outlet opening into said reaction vessel; and (b) a gas injector for injecting a gas stream into said discharge conduit so as to cause the solid particles falling into the collection hopper to flow continuously out of said hopper through said discharge conduit and to be fed into said reactor vessel in spite of any pressure differential that may exist between said collection hopper and said reactor vessel.
2. The apparatus of claim 1 wherein:
- the discharge conduit is rectilinear and coaxial with the exhaust conduit: and - the gas injector has an outlet nozzle mounted within the collection hopper adjacent the inlet of the discharge conduit so as to inject said gas stream axially within said discharge conduit.
- the discharge conduit is rectilinear and coaxial with the exhaust conduit: and - the gas injector has an outlet nozzle mounted within the collection hopper adjacent the inlet of the discharge conduit so as to inject said gas stream axially within said discharge conduit.
3. The apparatus of claim 2, wherein the inlet of said discharge conduit is throat-shaped.
4. The apparatus of claim 3, further comprising:
(c) means for controlling the amount of gas injected into said discharge conduit.
(c) means for controlling the amount of gas injected into said discharge conduit.
5. The combination of at least one apparatus as claimed in any one of claims 1 to 4, with a fluidized bed reactor including a reactor vessel containing a fluidized bed in which said flow of gaseous products containing solid particles to be separated is generated, wherein each of said at least one cyclone separator is mounted inside said reactor vessel and the outlet of the discharge conduit of each of said at least one cyclone separator is positioned within said fluidized bed.
6. The combination of claim 5, wherein:
- said reactor comprises an injection zone where a fluidizing medium is injected to generate said fluidized bed; and - the outlet of the discharge conduit of each apparatus is inserted deeply into said fluidized bed so as to feed back said gas stream and said collected solid particles in a zone close to said injection zone above the same.
- said reactor comprises an injection zone where a fluidizing medium is injected to generate said fluidized bed; and - the outlet of the discharge conduit of each apparatus is inserted deeply into said fluidized bed so as to feed back said gas stream and said collected solid particles in a zone close to said injection zone above the same.
7. The combination of claim 6, wherein the outlet of each discharge conduit has a diffusing section so as to disperse the gas stream and solid particles in the fluidized bed.
8. The combination of claim 7, wherein the reactor vessel comprises a solid conical diffuser mounted in the injection zone so as to be coaxial with the diffusing section of each discharge conduit and to cooperate with said diffusing section to disperse said gas stream and solid particles in the fluidized bed.
9. The combination of claim 6, wherein said fluidized bed reactor is used for the gasification of carboneous materials, and said gas stream consists of steam.
10. The combination of claim 7, wherein said fluidized bed reactor is used for the gasification of carboneous materials and said gas stream consists of steam.
11. The combination of claim 8, wherein said fluidized bed reactor is used for the gasification of carboneous materials and said gas stream consists of steam.
12. The combination of claim 5, comprising two of said at least one apparatus connected in series within the reactor vessel.
13. The combination of claim 6, comprising two of said at least one apparatus connected in series within the reactor.
14. The combination of claim 7, comprising two of said at least one apparatus connected in series within the reactor vessel.
15. The combination of claim 8, comprising two of said at least one apparatus connected in series within the reactor vessel.
16. The combination of claim 9, comprising two of said at least one apparatus connected in series within the reactor vessel.
17. The combination of claim 10, comprising two of said at least one apparatus connected in series within the reactor vessel.
18. The combination of claim 11, comprising two of said at least one apparatus connected in series within the reactor vessel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002151893A CA2151893A1 (en) | 1995-06-15 | 1995-06-15 | Apparatus for separating solid particles from a gas and for injecting the so-separated particles into a reaction vessel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002151893A CA2151893A1 (en) | 1995-06-15 | 1995-06-15 | Apparatus for separating solid particles from a gas and for injecting the so-separated particles into a reaction vessel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2151893A1 true CA2151893A1 (en) | 1996-12-16 |
Family
ID=4156058
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002151893A Abandoned CA2151893A1 (en) | 1995-06-15 | 1995-06-15 | Apparatus for separating solid particles from a gas and for injecting the so-separated particles into a reaction vessel |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2151893A1 (en) |
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| FR2855831A1 (en) * | 2003-06-04 | 2004-12-10 | Bertin Technologies Sa | DEVICE FOR COLLECTING PARTICLES AND MICROORGANISMS PRESENT IN AMBIENT AIR |
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1995
- 1995-06-15 CA CA002151893A patent/CA2151893A1/en not_active Abandoned
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2855831A1 (en) * | 2003-06-04 | 2004-12-10 | Bertin Technologies Sa | DEVICE FOR COLLECTING PARTICLES AND MICROORGANISMS PRESENT IN AMBIENT AIR |
| WO2004108880A3 (en) * | 2003-06-04 | 2005-05-06 | Bertin Technologies Sa | Device for collecting and separating particles and microorganisms present in the ambient air |
| CN100427580C (en) * | 2003-06-04 | 2008-10-22 | 贝尔坦技术有限公司 | Device for collecting and separating particles and microorganisms present in ambient air |
| US7452394B2 (en) | 2003-06-04 | 2008-11-18 | Bertin Technologies | Device for collecting and separating particles and microorganisms present in ambient air |
| CN108993763A (en) * | 2018-08-14 | 2018-12-14 | 中国恩菲工程技术有限公司 | Classifying cyclone, slime separation device, separation system and method for separating |
| CN109046748A (en) * | 2018-08-14 | 2018-12-21 | 中国恩菲工程技术有限公司 | Slime separation device, separation system and method for separating |
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| CN109717504A (en) * | 2019-02-18 | 2019-05-07 | 云南中烟工业有限责任公司 | A kind of fluidized bed type pneumatic separating cleaning tobacco leaf device and its cleaning tobacco leaf method |
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| Date | Code | Title | Description |
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| FZDE | Discontinued |