CN104762108A - Fluidized bed gasification furnace and gasification system - Google Patents

Abstract

The invention discloses a fluidized bed gasification furnace and a gasification system, relates to the technical field of gasification furnaces, and solves the problem that the fluidized bed gasification furnace in the prior art is difficult to simultaneously ensure the fluidization of large-particle pulverized coal and the gasification system. Prevent the problem of small particles of pulverized coal. The fluidized bed gasification furnace of the present invention comprises a gasification furnace body, the top of the gasification furnace body is provided with a solid material inlet, and the bottom is provided with a gasification agent inlet; the lower area of the gasification furnace body is is a gasification reaction zone, the bottom inner diameter of the gasification reaction zone is smaller than the top inner diameter of the gasification reaction zone. The invention is mainly applied in the field of gasification technology.

Description

Fluidized bed gasifier and gasification system

technical field

The invention relates to the technical field of gasification furnaces, in particular to a fluidized bed gasification furnace and a gasification system.

Background technique

Coal gasification is a thermochemical process in which pulverized coal (usually pulverized coal with a diameter of less than 5mm) is used as raw material to react with a gasification agent under high temperature and high pressure to generate crude gas and light tar.

In the field of coal gasification, the fluidized bed gasifier is a commonly used coal gasification reaction device. The gas flow rate of the gasification agent reaches the minimum fluidization velocity of pulverized coal particles, so that the pulverized coal is in a suspended state and fully contacts with the gasification agent for gasification reaction. Among them, under the action of gravity, the pulverized coal particles will self-stratify, that is, part of the pulverized coal with large particles will sink into the gas distribution plate area at the lower part of the gasifier, which will easily cause the pulverized coal with large particles to accumulate at the bottom of the gasifier. A flow dead zone occurs. Specifically, in order to avoid the dead zone phenomenon of large-particle pulverized coal at the bottom of the gasifier, the gas flow rate of gasification agent can be increased to improve the flow state of large-particle pulverized coal; however, as the gasification reaction proceeds, the gasification The gas volume in the gasifier will increase, and the increase in gas volume will lead to an increase in the gas flow rate, which will easily cause small particles of pulverized coal to be taken out of the gasifier.

Therefore, when feeding the gasification agent into the fluidized bed gasifier, the most ideal situation is: the gas flow rate of the gasification agent must ensure that the large particles of pulverized coal reach a flow state, thereby avoiding the fluidized bed gasifier. At the same time, as the gasification reaction proceeds, the gas flow rate of the gasification agent should not be too high, so as not to bring too many small particles of pulverized coal out of the gasifier, resulting in a reduction in the utilization efficiency of pulverized coal.

However, in the prior art, the gas flow rate of the gasification agent in the fluidized bed gasifier usually increases with the progress of the reaction, so it is difficult to ensure the fluidization of large-particle pulverized coal and prevent the flow of small-particle pulverized coal at the same time. Bring out.

Contents of the invention

The invention provides a fluidized bed gasification furnace and a gasification system, which solves the problem that the fluidized bed gasification furnace in the prior art can not only ensure the fluidization of large particle pulverized coal, but also prevent small particle pulverized coal from being carried out. The problem.

To achieve the above object, the present invention adopts the following technical solutions:

A fluidized bed gasification furnace, comprising a gasification furnace body, the top of the gasification furnace body is provided with a solid material inlet, and the bottom is provided with a gasification agent inlet; the lower area of the gasification furnace body is a gasification In the reaction zone, the inner diameter at the bottom of the gasification reaction zone is smaller than the inner diameter at the top of the gasification reaction zone.

Wherein, the ratio of the inner diameter at the top of the gasification reaction zone to the inner diameter at the bottom of the gasification reaction zone is d, and 1<d≤2.

Further, the included angle between the inner cylinder wall of the gasification reaction zone in the gasifier body and the horizontal direction is 75°-85°.

In practical application, the middle and upper area inside the gasifier body is a pyrolysis zone, and the inner wall of the gasifier body is provided with a buffer neck at the bottom of the pyrolysis zone.

Wherein, the inner diameter of the neck corresponding to the minimum cross-sectional area of the buffer neck is smaller than the inner diameter of the upper and lower openings of the buffer neck, so that the gas flow rate of the gasification agent passing through the buffer neck is not greater than the minimum of the material. fluidization velocity.

Specifically, the minimum fluidization velocity of the material refers to the minimum fluidization velocity of the average particle size of the material.

Preferably, the connection position between the buffer neck and the gasifier body, and the neck diameter position in the buffer neck are both arc transition structures.

Further, the setting range corresponding to the included angle between the two side walls on the same side of the buffer constriction should be able to ensure that the material in the gasification furnace body falls smoothly from the pyrolysis zone to the gasification reaction district.

In actual application, the included angle between the upper and lower sidewalls on the same side of the buffer constriction is 60°-180°.

Preferably, the included angle between the upper and lower sidewalls on the same side of the buffer constriction is 80°-120°.

The fluidized bed gasification furnace provided by the present invention includes a gasification furnace body, the top of the gasification furnace body is provided with a solid material inlet, and the bottom is provided with a gasification agent inlet; the lower area of the gasification furnace body is for the gasification reaction zone, the inner diameter of the bottom of the gasification reaction zone is D1, the inner diameter of the top of the gasification reaction zone is D2, and D1 is smaller than D2. From this analysis, it can be seen that, taking coal gasification reaction as an example, the pulverized coal enters the gasifier body through the solid material inlet at the top, and the gasification agent enters the gasifier body through the gasification agent inlet at the bottom, and combines with the pulverized coal In the gasification reaction zone, there is sufficient contact and gasification reaction occurs. Among them, the inner diameter of the bottom end of the gasification reaction zone is D1, and the inner diameter of the top end of the gasification reaction zone is D2, and D1 is smaller than D2. Therefore, the diameter of the inner cylinder of the gasification reaction zone in the gasification furnace body gradually increases from D1 to D2, so as the gasification reaction progresses, when the gas volume in the gasification reaction zone increases, the increase in the diameter of the gasification reaction zone in the gasifier body can effectively offset the increase in the gas volume, thereby maintaining the gas flow rate of the gasification agent. remain unchanged or decrease. Therefore, the variable diameter design of the fluidized bed gasifier provided by the present invention in the gasification reaction zone can match the gas flow rate of the gasification agent with the coal gasification reaction, thereby effectively solving the difference in the flow properties of large and small pulverized coal particles. The resulting difficulty in the operation of the fluidized bed gasifier can improve the flow state of large-particle pulverized coal, and at the same time reduce the problem of small-particle pulverized coal carryover, so that the coal gasification reaction can be more complete and the utilization rate of pulverized coal can be improved.

The present invention also provides a gasification system, including the fluidized bed gasification furnace described in any one of the above.

The gasification system provided by the present invention has the same advantages as the fluidized bed gasifier, so details will not be repeated here.

Description of drawings

Fig. 1 is a schematic structural view of a fluidized bed gasifier provided by an embodiment of the present invention;

Fig. 2 is an enlarged structural schematic diagram of a gasification reaction zone in a fluidized bed gasifier provided by an embodiment of the present invention;

Fig. 3 is a schematic structural view of another fluidized bed gasifier provided by an embodiment of the present invention;

Fig. 4 is an enlarged structural schematic diagram of another pyrolysis zone in a fluidized bed gasifier provided by an embodiment of the present invention;

Fig. 5 is a schematic structural diagram of a gasification system provided by an embodiment of the present invention.

In the figure, 1-gasifier body; 11-solid material inlet; 12-gasification agent inlet; 2-gas distribution plate; 3-buffer neck; 4-ash discharge system; 5-gas-solid separation system; A- Gasification reaction zone; B-pyrolysis zone.

Detailed ways

A fluidized bed gasification furnace and a gasification system provided by embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

An embodiment of the present invention provides a fluidized bed gasifier, as shown in Figure 1, comprising a gasifier body 1, the top of the gasifier body 1 is provided with a solid material inlet 11, and the bottom is provided with a gasification agent inlet 12; The lower area inside the gasification furnace body 1 is the gasification reaction zone A, the bottom inner diameter of the gasification reaction zone A is D1, the top inner diameter of the gasification reaction zone A is D2, and D1 is smaller than D2.

The fluidized bed gasifier provided in the embodiment of the present invention includes a gasifier body, the top of the gasifier body is provided with a solid material inlet, and the bottom is provided with a gasification agent inlet; the lower area of the gasifier body is a gasifier. The inner diameter of the bottom of the gasification reaction zone is D1, and the inner diameter of the top of the gasification reaction zone is D2, and D1 is smaller than D2. From this analysis, it can be seen that, taking coal gasification reaction as an example, the pulverized coal enters the gasifier body through the solid material inlet at the top, and the gasification agent enters the gasifier body through the gasification agent inlet at the bottom, and combines with the pulverized coal In the gasification reaction zone, there is sufficient contact and gasification reaction occurs. Among them, the inner diameter of the bottom end of the gasification reaction zone is D1, and the inner diameter of the top end of the gasification reaction zone is D2, and D1 is smaller than D2. Therefore, the diameter of the inner cylinder of the gasification reaction zone in the gasification furnace body gradually increases from D1 to D2, so as the gasification reaction progresses, when the gas volume in the gasification reaction zone increases, the increase in the diameter of the gasification reaction zone in the gasifier body can effectively offset the increase in the gas volume, thereby maintaining the gas flow rate of the gasification agent. remain unchanged or decrease. Therefore, the fluidized bed gasifier provided by the embodiment of the present invention is designed to change the diameter of the gasification reaction zone, so that the gas flow rate of the gasification agent can be matched with the coal gasification reaction, thereby effectively solving the flow of large and small pulverized coal particles. The operation difficulty of the fluidized bed gasifier caused by the difference in properties can improve the flow state of large-particle pulverized coal and reduce the problem of carrying out of small-particle pulverized coal, so that the coal gasification reaction can be more complete and the utilization of pulverized coal can be improved Rate.

What needs to be added here is that when the gasification agent continues upward from the gasification reaction zone A and enters the equal-diameter gasifier body 1 with an inner diameter of D2, the gas flow rate can remain unchanged, and the gas flow rate can be lower than that of small particle powder Therefore, it can effectively prevent the small particles of pulverized coal in the gasifier body 1 from being carried out, thereby improving the utilization efficiency of pulverized coal.

In actual application, in order to make the gasification agent entering the gasification furnace body 1 from the gasification agent inlet 12 uniformly dispersed in the gasification reaction zone A, so as to improve the efficiency of the gasification reaction, it can be placed inside the gasification furnace body 1 A gas distribution plate 2 is provided near the gasification agent inlet 12 , so that the gasification agent can be evenly dispersed to the gasification reaction zone A through the through holes on the gas distribution plate 2 . Among them, in order to improve the efficiency of the gasification agent entering the gasification furnace body 1, as shown in Figure 2, two gasification agent inlets 12 can be provided, so that the gasification agent inlet 12 can simultaneously enter the gasification furnace body. 1 into the gasification furnace to increase the inflow of the gasification agent per unit time, thereby increasing the efficiency of the gasification agent entering the gasification furnace body 1 . Specifically, in order to enable the gas distribution plate 2 to cooperate with the two gasification agent inlets 12, as shown in Fig. The gasification agent flowing through one of the inlets can directly enter the gasification reaction zone A, and the gasification agent flowing through the other inlet can enter the gasification reaction zone A evenly through the gas distribution plate 2, and then the gasification agent can pass through both way into the gasification reaction zone A, and fully contact with pulverized coal and strong gasification reaction.

What needs to be added here is that, in order to avoid dead angles in the gasifier body 1 and affect the progress of the coal gasification reaction, as shown in Figures 1 and 2, the bottom end of the gasifier body 1 has an arc-shaped structure, that is, the gasifier body 1 has an arc-shaped structure. The transition between the side wall and the bottom wall of the gasification furnace body 1 is arc-shaped, so as to avoid dead angle areas in the gasification furnace body 1 with a right-angle structure, which will affect the progress of the gasification reaction.

Specifically, the actual lengths of the above-mentioned D1 and D2 can be reasonably set according to the characteristics of the material or the nature of the coal type. In the fluidized bed gasifier provided in the embodiment of the present invention, in order to keep the large particle pulverized coal in a stable flow state, At the same time to reduce the carry-over of small particle pulverized coal, the ratio of D2 and D1 above can be d, and the d can be preferably 1<d≤2, so that the setting of this ratio can make the gas distribution plate 2 area well The gas flow velocity of the gasification agent is greater than the initial fluidization velocity of the large-particle pulverized coal, and smaller than the drag-out velocity of the small-particle pulverized coal.

Further, in order to make the space of the gasification reaction zone A larger to facilitate the gasification reaction, as shown in Figure 1 and Figure 2, the inner cylinder wall of the gasification reaction zone A in the gasification furnace body 1 is aligned with the horizontal direction The included angle can be 75-85 degrees, so as to ensure that the transition section height of the gasification reaction zone A is relatively long, so as to increase the reaction space, which in turn facilitates the coal gasification reaction in the gasification reaction zone A to be more fully and stably conduct.

In the practical application of coal gasification reaction, after the pulverized coal enters the gasifier body 1, it falls quickly from the solid material inlet 11 under the action of its own gravity. The falling process at the upper pyrolysis zone B cannot fully react effectively, and after falling to the gasification reaction zone A and contacting the high-temperature gasification agent, the temperature of the pulverized coal will rise rapidly, and the temperature will exceed the maximum temperature of pyrolysis. If the temperature is not optimal, the pulverized coal cannot be fully pyrolyzed, which will eventually lead to a decrease in the utilization rate of the pulverized coal.

In another fluidized bed gasifier provided by the embodiment of the present invention, in order to solve the above-mentioned problem that the pulverized coal falls at a faster rate in the pyrolysis zone B, as shown in Figure 3 and Figure 4, the gasifier body 1 A buffer constriction 3 may be provided at the pyrolysis zone B in the middle and upper region, and the buffer constriction 3 may be specifically provided on the inner wall of the gasifier body 1 . Therefore, at the pyrolysis zone B, the buffer neck 3 can be used to adjust the gas flow rate in the gasification furnace body 1, thereby prolonging the time for the pulverized coal to fall from the solid material inlet 11 to the gasification reaction zone A, and then make the pulverized coal Fully respond to improve its utilization.

Wherein, the inner diameter of the neck corresponding to the minimum cross-sectional area of the buffer neck 3 can be D3, the inner diameter of the upper and lower openings can be D2, and D3 is smaller than D2; in actual production, the specific structure of the buffer neck 3 is not described here. As long as it can ensure that the gas flow rate of the gasification agent passing through the buffer neck 3 is not greater than the minimum fluidization velocity of the material. Specifically, in order to facilitate the manufacture of the cushioning constriction 3 and ensure that it has a good cushioning effect, as shown in Figure 3 and Figure 4, the cushioning constriction 3 can be a "><" type structure, and the "><" type structure The internal diameter of the buffer constriction 3 in the middle part can be D3, and the internal diameter of the upper and lower openings can be D2, that is, D3<D2. Since the internal diameter D3 of the central constriction of the buffer constriction 3 is smaller than the internal diameter D2 of the gasifier body 1 (the inner diameter D2 of the upper and lower openings of the buffer constriction 3), the gas flow rate of the gasification agent at the buffer constriction 3 is relatively high, and the gas flow rate The improvement of can generate drag force, so as to offset part of the gravity of the pulverized coal, and then play a buffer role in the falling of the pulverized coal, so that the pulverized coal can accumulate in the pyrolysis zone B, and prolong the life of the pulverized coal in the pyrolysis zone B. dwell time. Another fluidized bed gasifier provided by the embodiment of the present invention can allow enough time for the pulverized coal to undergo pyrolysis reaction with the gasification agent from the gasification reaction zone A, thereby effectively increasing pyrolysis products such as tar and methane , and to improve the economy of the gasification process.

Specifically, the minimum fluidization velocity of the above-mentioned materials may refer to the minimum fluidization velocity of the average particle diameter of the material; The minimum fluidization velocity, so that the drag force generated by the increased gas flow rate can offset part of the gravity of the material, and the setting range corresponding to the included angle between the two side walls on the same side of the buffer neck 3 should be able to ensure that the material is in the air. The interior of the furnace body 1 falls smoothly from the pyrolysis zone B to the gasification reaction zone A. Furthermore, the included angle between the upper and lower sidewalls on the same side of the buffer constriction 3 can be 60-180 degrees, preferably 80-120 degrees; applied to the "><" type structure provided by the embodiment of the present invention 3 and 4, the angle between the upper and lower inclined side walls of the buffer neck 3 of the above-mentioned "><" type structure can be 80-120 degrees.

Among them, in order to avoid the formation of dead corners at the buffer constriction 3 in the gasifier body 1 and affect the gasification effect of the fluidized bed gasifier, as shown in Figures 3 and 4, the fluidized bed provided by the embodiment of the present invention The connection position between the buffer neck 3 and the gasifier body 1 in the gasifier, and the neck diameter position in the buffer neck 3 can both be arc-shaped transition structures.

The fluidized bed gasifier provided by the embodiment of the present invention combines the operation of the gasifier and the catalytic gasification process to solve the problem of the gas flow rate of the gasification agent and the fluidization state of the pulverized coal particles during the operation of the fluidized bed gasifier. Reaction matching problem, so that the pulverized coal pyrolysis is more sufficient, and the flow state in the gasifier is improved to fully react the pulverized coal, thereby improving the utilization efficiency of the pulverized coal.

An embodiment of the present invention also provides a gasification system, as shown in FIG. 5 , including the fluidized bed gasifier described in any one of the above. Wherein, the bottom end of the fluidized bed gasification furnace can be connected with an ash discharge system 4, and the top side wall of the fluidized bed gasification furnace can be connected with a gas-solid separation system 5, so that pulverized coal can enter the gasification through the solid material inlet 11 Furnace body 1, and falls to the pyrolysis zone B in the middle and upper part, and the pyrolysis reaction occurs; then the pulverized coal continues to fall to the gasification reaction zone A, contacts with the gasification agent and undergoes gasification reaction; After the reaction and gasification reaction, the pulverized coal is discharged from the gasifier through the ash discharge system 4 at the bottom of the gasifier body 1; The separation system 5 is discharged from the gasifier, and the gas-solid separation can be carried out through the cyclone separator, so that the separated solid powder can be returned to the bottom gasification reaction zone A in the gasifier body 1 for another reaction, and the separated The final gas phase product enters the subsequent cooling system for subsequent processing.

In the fluidized bed gasification furnace and gasification system provided by the embodiments of the present invention, the structure of the fluidized bed gasification furnace is set according to the characteristics of the gasification reaction, which can adjust the change of the gas flow rate during the gasification reaction process and control the flow of materials , so as to effectively improve the flow state in the bottom area of the gasifier, avoid the flow dead zone, thereby increasing the residence time of large particle materials in the furnace, and improving the conversion rate of large particle materials, and at the same time avoiding the carryover of small particle materials In order to improve the utilization efficiency of materials and reduce the processing pressure of subsequent systems. In addition, the setting of the buffer neck in the pyrolysis zone in the fluidized bed gasifier can effectively prolong the residence time of pulverized coal in the pyrolysis zone, so that the pulverized coal can fully undergo hydropyrolysis reaction, thereby improving the utilization rate of coal. Pyrolysis products such as tar and methane are added, and the yield of tar can be increased from 1-2% of the traditional gasifier to 3-5%, thereby effectively improving the economy of the gasification process.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. All should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (12)

1. A fluidized bed gasifier, comprising a gasifier body, the top of the gasifier body is provided with a solid material inlet, and the bottom is provided with a gasification agent inlet; the lower area in the gasifier body is The gasification reaction zone is characterized in that the bottom inner diameter of the gasification reaction zone is smaller than the top inner diameter of the gasification reaction zone. 2. The fluidized bed gasifier according to claim 1, wherein the ratio of the inner diameter of the top end of the gasification reaction zone to the inner diameter of the bottom end of the gasification reaction zone is d, and the 1< d≤2. 3 . The fluidized bed gasifier according to claim 1 , wherein the included angle between the inner cylinder wall of the gasification reaction zone in the gasifier body and the horizontal direction is 75°-85°. 4 . 4. The fluidized bed gasification furnace according to claim 1, characterized in that, the middle and upper region in the gasification furnace body is a pyrolysis zone, and the inner wall of the gasification furnace body is in the pyrolysis zone The bottom has a cushioning neck. 5. The fluidized bed gasifier according to claim 4, characterized in that, the inner diameter of the buffer neck corresponding to the minimum cross-sectional area is smaller than the inner diameter of the upper and lower openings of the buffer neck, so that The gas flow rate passing through the buffer neck is not greater than the minimum fluidization velocity of the material. 6. The fluidized bed gasifier according to claim 5, wherein the minimum fluidization velocity of the material refers to the minimum fluidization velocity of the average particle size of the material. 7. The fluidized bed gasifier according to claim 4, characterized in that, the connection position between the buffer neck and the gasifier body, and the neck diameter position in the buffer neck are both It is an arc transition structure. 8. The fluidized bed gasifier according to any one of claims 4-7, characterized in that, the setting range corresponding to the angle between the two side walls on the same side of the buffer constriction should be able to ensure that the material The body of the gasifier falls smoothly from the pyrolysis zone to the gasification reaction zone. 9 . The fluidized bed gasifier according to claim 8 , wherein the included angle between the upper and lower side walls on the same side of the buffer constriction is 60°-180°. 10 . The fluidized bed gasifier according to claim 9 , wherein the included angle between the upper and lower side walls on the same side of the buffer constriction is 80°-120°. 11. The fluidized bed gasification furnace according to claim 1, characterized in that a gas distribution plate is provided inside the gasification furnace body adjacent to the gasification agent inlet area, and the gas distribution plate is downward Conical funnel-shaped structure set at a slant. 12. A gasification system, characterized by comprising the fluidized bed gasifier according to any one of claims 1-11.