WO2011029285A1

WO2011029285A1 - Multi-layer fluidized bed gasifier

Info

Publication number: WO2011029285A1
Application number: PCT/CN2010/001410
Authority: WO
Inventors: 毕继诚; 李克忠; 程相龙; 曲旋; 张�荣; 孙东凯; 李金来; 甘中学
Original assignee: 新奥科技发展有限公司
Priority date: 2009-09-14
Filing date: 2010-09-14
Publication date: 2011-03-17

Abstract

A multi-layer fluidized bed gasifier, comprising: a gasifier case (3); at least two layers of gas distributors (2) which are in the form of perforated plates, arranged perpendicularly to the longitudinal axis of the case and at different heights along the longitudinal axis, separating the interior space into an upper space (A), a middle space (B), and a lower space (C); a raw material inlet (4); a slag outlet (7) and a gasifying agent inlet which are located at the bottom of the case; a coal- gas outlet located at the top of the case. First and second overflow devices (1) which are tubular in form and open at both ends, are respectively arranged through the first and second gas distributors. The overflow devices allow the raw material to flow from the top down along a zigzag line. The raw material flows from the upper space (A) through the first overflow device to the middle space (B), and then from the middle space through the second overflow device into the lower space (C).

Description

Multi-layer fluidized bed gasifier

In general, the present invention relates to a gasifier, and more particularly to a multi-layer fluidized bed gasifier for gasification of coal to produce a methane-rich gas. Background technique

The invention relates to a multi-layer fluidized bed gasification furnace device for preparing a methane-rich gas by gasification of a pulverized coal multi-layer fluidized bed.

China is a country rich in coal and oil-poor. With the rapid development of society and economy, China's natural gas demand has risen sharply, and the proportion in the energy structure has increased rapidly. While domestic natural gas is still in the early stage of exploration and development, imports are also in their infancy, and supply capacity is seriously lagging behind, resulting in an increasingly prominent contradiction between natural gas supply and demand. Using coal with relatively large resource advantages in China, it can be gasified to produce gas, which not only promotes the efficient and clean utilization of coal, but also utilizes existing natural gas pipelines to effectively alleviate the supply and demand of natural gas at a lower economic cost. Contradictions, this is a powerful measure for the comprehensive utilization of coal resources.

The usual coal gasification and methane production process, that is, the gasification agent composed of oxygen (or air) and/or water vapor (H ₂ 0) at a high temperature is gasified in a single-layer gasification furnace to form a gasification reaction. A small amount of decane (CH ₄ ) synthesis gas (mainly hydrogen, carbon monoxide and carbon dioxide), followed by a water gas shift and a decaneization process, and a two-step process for the preparation of decane. The disadvantages of this type of coal gasification process are: The gasification reaction has high energy consumption, high requirements on equipment, and requires three reaction devices, complicated processes, and the like.

The catalytic gasification of coal to produce methane is an important way to clean and use coal. The catalytic gasification technology of coal is used. The coal is mainly composed of water vapor (H ₂ 0 ) and hydrogen (H ₂ at relatively low temperature). ), a gas mixture of carbon monoxide (CO) is subjected to a gasification reaction under the catalytic action of a catalyst to form a high concentration of methane (CH ₄ ). 0

At present, the coal-catalyzed gasification process for preparing methane technology mentioned in the related patent uses cryogenic separation to separate methane from gas production with carbon monoxide and hydrogen, and recycles hydrogen and carbon monoxide in the reaction gas to the gasifier. The methanation reaction is converted to methane in a gasifier to increase the production of system methane. This coal catalytic gasification process can be carried out in a single-layer gasifier, but has the disadvantages of low gasification reaction rate, long reaction time, low carbon conversion rate, high investment in gas separation system, and the like; In order to meet the heat balance of the reactor, the coal catalytic gasification process needs to heat the superheated steam into the higher temperature, and the steam superheating system and the heat exchange system have higher load and poor economy.

U.S. Patent 4,077,778 teaches the use of a multi-stage fluidized bed to effect catalytic gasification of coal to increase carbon conversion. The mainstream bed operation has a higher gas velocity, and some carbon particles are entrained to the secondary fluidized bed, and the gasification reaction is carried out at a lower gas velocity, the solid phase residence time is increased, and the carbon conversion rate is maximized. Compared with single-stage gasification, multi-stage gasification can increase carbon utilization from 70-85% to over 95%. The multi-stage fluidized bed coal catalytic gasification process adopts multi-stage fluidized bed, which has high equipment investment and complicated operation.

U.S. Patent No. 4,094,650 teaches the use of an alkali metal catalyzed gasification of a carbonaceous solid to produce methane which is recovered for reuse. The water-soluble catalyst is recovered by multistage washing, and the insoluble catalyst is recovered by lime digestion. U.S. Patent No. 0,277,437, based on U.S. Patent No. 4,094,650, which utilizes a primary treatment to separate the alkali metal material from the reactor solid residue, simplifies the alkali metal catalyst recovery process, and improves the economics and overall efficiency of the catalytic gasification process, but The recycling system is still complicated and the recycling method is expensive.

The United States Exxon has conducted a large number of experimental studies on coal one-step methane technology. U.S. Patent No. 4,318,712 discloses a whole process for direct decaneization of coal. The coal is pre-mixed with the catalyst before entering the coal gasification reactor, and the superheated steam is used not only as a gasifying agent but also as a heat source. The reaction temperature in the furnace was maintained, and the temperature in the furnace was controlled at 700. C or so, superheated steam temperature 850. C, gasifier reaction pressure The force is 3.5 MPa, and the coal reacts with the superheated steam under the action of the catalyst to directly obtain the product rich decane gas. GPE of the United States has conducted further research on the basis of EXXON process technology. U.S. Patent No. 20070000177A1 also discloses a process for direct methanation of coal. The catalyst is an alkali metal carbonate or an alkali metal hydroxide, and the gasifying agent is water vapor. The main technical features, in addition to the addition of a highly efficient decane catalyst, calcium oxide is added to the reacted pulverized coal to absorb the carbon dioxide produced during the reaction, thereby further increasing the decane content. In this process, although a catalyst for promoting methane generation is added, since the high temperature is disadvantageous for the formation of methane, the reaction temperature is generally controlled at 700. Around C, the reaction rate is slow, the conversion rate of carbon is low, the heat of the external heating system is difficult to maintain, and the operation of the catalyst recovery unit is increased, and the catalyst recovery effect directly affects the production cost.

In addition, in order to make full use of heat to produce gas, U.S. Patent No. 5,064,444 proposes to divide a fluidized bed gasifier into a pyrolysis section, a gasification section, and a cooling section in the case of pressurized steam vaporization. Separate with a partition. A serpentine coil (snake heat exchanger) is placed in the pyrolysis section and the gasification section of the gasification furnace, and 900 is introduced therein. C~950. The high temperature gas of C (such as the gas after the combustion of the fuel) heats the coal powder to provide the heat required for gasification and pyrolysis to obtain the gas. The fluidized bed gasifier can be either vertical or horizontal, with a capacity of 700. The superheated steam of C~800'C is a gasifying agent, and the cooling section is supplied with saturated steam and pneumatically fed. The device prolongs the residence time of the pulverized coal, is favorable for solid phase processing, and has high utilization rate of heat energy, but the utilization rate of the reaction volume in the gasification furnace is low, which affects solid phase processing; the residual carbon content in the vertical furnace operation is high, It is difficult to use effectively; compared with gas-solid contact heat transfer, the heat transfer rate is slow, and the solid phase in the bed is unevenly heated; at the same time, the equipment is complicated, especially the horizontal furnace.

Therefore, it is of far-reaching significance to study the gasification technology for efficient utilization of coal quality and to develop a corresponding gasification device with low investment and simple process for gasification to produce methane-rich gas. Summary of the invention

In view of the above circumstances, the present invention has been made in an effort to provide a gasification apparatus rich in methane gas by using a low-investment, process-pulverized coal gasification process.

In order to achieve the above object, the present invention provides a multi-layer fluidized bed gasification furnace for gasification of coal to produce a gas rich in decane gas, the fluidized bed gasification furnace comprising:

a gasifier housing having a vertical longitudinal axis defining an interior space therein;

At least two layers of gas distributors in the interior space of the housing that are perpendicular to the longitudinal axis and are arranged at different heights along the longitudinal axis, in the form of orifices, the at least two layers of gas distribution The first gas distributor and the second gas distributor located below the first distributor, the first gas distributor and the second distributor separating the internal space of the casing into an upper layer Space, intermediate space and lower space;

a raw material inlet disposed at an upper portion of a side of the casing, the raw material inlet leading to the upper space for inputting raw materials into the upper space, the overall flow direction of the raw material is from top to bottom along the longitudinal axis ;

a ash outlet located at the bottom of the housing;

a gasification agent inlet for vaporizer entry near a side of the ash outlet at the bottom of the housing, the overall flow direction of the gasifying agent being bottom-up along the longitudinal axis;

a gas outlet at the top of the housing;

The first gas distributor is provided with a first overflow device in a tubular form open at both ends, and the second gas distributor is provided with a second overflow device in a tubular form with both ends open. The first overflow device and the second overflow device are configured to move the raw material from top to bottom along a tortuous line, and flow from the upper space to the intermediate layer space through the first overflow device, and then The intermediate layer space flows into the lower space through the second overflow device, The lower end of the first overflow device and the upper end of the second overflow device are spaced apart from each other in a horizontal direction perpendicular to the longitudinal axis to prevent the material from passing straight down.

In a preferred embodiment of the present invention, the shortest distance between the upper end of the first overflow device and the inner wall of the gasifier housing is within the inner diameter of the gasifier housing.

1/5 times to 1/2 times, and preferably between 1/3 times and 1/2 times, and the shortest distance between the lower end outlet and the inner wall of the gasifier housing is in the gasifier Between 1/10 and 1/6 times the inner diameter of the housing, and

The shortest distance between the upper end of the second overflow device and the inner wall of the gasifier housing is between 1/5 and 1/2 times the inner diameter of the gasifier housing, and preferably

Between 1/3 and 1/2 times, and the shortest distance between the lower end outlet and the inner wall of the gasifier housing is between 1/10 and 1/6 times the inner diameter of the gasifier housing .

In a preferred embodiment of the invention, the projections of the upper and lower outlets of the first overflow means are spaced apart from each other on a horizontal plane perpendicular to the longitudinal axis.

In another preferred embodiment of the invention, the first overflow means forms an angle with the longitudinal axis that is greater than or equal to the angle of repose of the coal feedstock. The angle of repose of coal raw materials varies according to environmental factors such as coal particle size, temperature, humidity and pressure. In actual production, the angle of repose of coal under real gasification conditions is determined by various factors of real coal gasification. The range of the angle is selected based on the principle that the angle of the angle is greater than or equal to the angle of repose of the coal under real gasification conditions.

In another preferred embodiment of the invention the first overflow means forms an angle of less than or equal to 60 with the longitudinal axis.

In another preferred embodiment of the present invention, the first overflow device includes an upper section and a lower section, and an upper section of the first overflow device is parallel to the longitudinal axis, and a lower section of the first overflow device The longitudinal axis forms an angle greater than or equal to the angle of repose of the coal material, and the arc between the upper and lower sections of the first overflow device Connected.

In another preferred embodiment of the present invention, the first overflow device includes an upper section and a lower section, and an upper section of the first overflow device is parallel to the longitudinal axis, and a lower section of the first overflow device The longitudinal axis forms less than or equal to 60. The angle between the lower section of the first overflow means and the longitudinal axis preferably forms an angle of between 30 and 50, most preferably 45. Angle of inclusion (the angle of repose of coal raw materials varies according to environmental factors such as coal particle size, temperature, humidity and pressure. In actual production, the parameters of various factors in real coal gasification are used to determine coal under real gasification conditions. The angle of repose, and the range of the angle is greater than or equal to the angle of repose of the coal under real gasification conditions, to select the range of the angle), between the upper and lower sections of the first overflow device The arc transitions are connected.

In a preferred embodiment of the invention, the projections of the upper and lower outlets of the second overflow means are spaced apart from each other on a horizontal plane perpendicular to the longitudinal axis.

In another preferred embodiment of the invention, the second overflow means forms an angle with the longitudinal axis that is greater than or equal to the angle of repose of the coal feedstock. The angle of repose of coal raw materials varies according to environmental factors such as coal particle size, temperature, humidity and pressure. In actual production, the angle of repose of coal under real gasification conditions is determined by various factors of real coal gasification. The range of the angle is selected based on the principle that the angle of the angle is greater than or equal to the angle of repose of the coal under real gasification conditions.

In another preferred embodiment of the invention, the second overflow means forms an angle of less than or equal to 60 with the longitudinal axis.

In another preferred embodiment of the present invention, the second overflow device includes an upper section and a lower section, an upper section of the second overflow device is parallel to the longitudinal axis, and a lower section of the second overflow device is The longitudinal axis forms an angle greater than or equal to the angle of repose of the coal material, and the upper and lower sections of the second overflow device are connected by a circular arc transition. In another preferred embodiment of the present invention, the second overflow device includes an upper section and a lower section, an upper section of the second overflow device is parallel to the longitudinal axis, and a lower section of the second overflow device is The longitudinal axis forms less than or equal to 60. The angle between the lower section of the second overflow device and the longitudinal axis is preferably 30. At an angle of up to 50°, it is most preferred to form 45. Angle of inclusion (the angle of repose of coal raw materials varies according to environmental factors such as coal particle size, temperature, humidity and pressure. In actual production, the parameters of various factors in real coal gasification are used to determine coal under real gasification conditions. The angle of repose, and the range of the angle is greater than or equal to the angle of repose of the coal under real gasification conditions to select the range of the angle), between the upper and lower sections of the second overflow device The arc transitions are connected.

In a preferred embodiment of the invention, at least one of the longitudinally central portion or the longitudinally lower portion of the housing is further provided with an auxiliary feed port.

In a preferred embodiment of the present invention, at least one gas distributor for further separating the space is further disposed in any one of the upper space, the intermediate space, and the lower space, and the at least one An overflow device arranged by a layer gas distributor.

In a preferred embodiment of the present invention, in the casing, a third gas distributor is further disposed below the second gas distributor.

In a preferred embodiment of the invention, the third gas distributor has a funnel shape.

In a preferred embodiment of the present invention, the portion of the overflow device above the gas distributor is an overflow weir, and the height of the weir is calculated by the solid phase processing time and the bed layer:

The overflow height of a particular layer, in _m

w... the amount of solid particles fed in this layer, in kg/h

T—the solid phase processing time of this layer, the unit is h D -- the inner diameter of the furnace body, the unit is nr

P -- the density of the bed under operating conditions in k _g /m ³

s ... the porosity of the bed under operating conditions.

In a preferred embodiment of the invention,

The distance between two adjacent gas distributors is determined by the height of the overflow device between them and the height of the bed holding capacity, which is calculated by:

H^!+hx-hz

among them

H -- the distance between two adjacent gas distributors, in units of m;

_Hl —the height of the overflow device between the two gas distributors, in m; h _l — the height of the material holding amount between the two gas distributors, in units of m;

h ₂ - the depth of the buried layer of the overflow device between the two gas distributors, in m.

Brief description of the process used in the use of the apparatus of the invention

The impregnated catalyst coal powder is added to the intermediate layer space B (catalytic gasification zone) of the three-layer fluidized bed gasifier under the action of the rotary feeder; the raw coal is added from the upper pyrolysis section of the reactor, and successively passes through multiple layers of fluidization. Bed gasifier upper space A (partial pyrolysis zone), intermediate zone space B (catalytic gasification zone) and lower zone space C (residual gasification zone). In a part of the pyrolysis zone, the high-temperature hot gas generated by the reaction heats the feed cold coal powder to cause partial pyrolysis to produce a product rich in methane-rich pyrolysis gas and tar. After that, the partially pyrolyzed coal powder enters the catalytic gasification zone, and catalytic gasification, decaneization and the like are generated under the action of the catalyst to generate effective gas components such as methane, carbon monoxide and hydrogen, and carbon dioxide, a small amount of hydrogen sulfide and ammonia. Wait. The unreacted coal residue enters the residue gasification zone and is gasified to generate carbon monoxide, hydrogen, carbon dioxide and other gases under the action of oxygen and water vapor, while carbon monoxide and hydrogen enter the upper catalytic gasification zone, and decane occurs under the action of the catalyst. Chemical reaction, increase system decane yield, high temperature Water vapor provides some heat to the catalytic gasification zone. Control the process conditions of the residue gasification zone to realize the separation of ash, coke and catalyst. At high temperature, some of the catalysts enter the upper catalytic gasification zone in gaseous form and participate in the gasification reaction. The gaseous catalyst enters part of the pyrolysis zone, and the temperature decreases to make the catalyst exist. The morphological changes are separated from the gaseous products, and remain in the furnace to continue to participate in the gasification reaction to achieve recycling of the catalyst in the furnace. The gas of the gasifier exits through the isothermal dust filter unit, and the filtered dust is returned to the gasification furnace to continue the gasification reaction, and the filtered gas is sent to the gas-liquid cooling separation unit for gas-liquid separation to obtain low-temperature tar and Crude gas. Thereafter, the crude gas enters the gas purifying device to remove acid gases such as carbon dioxide and hydrogen sulfide, thereby obtaining a gas rich in decane.

Introduction to the advantages of the present invention

(1) retaining the characteristics and advantages of catalytic gasification, obtaining a higher content of methane, and overcome the difficulties of separate catalytic gasification, such as longer reaction time and higher carbon content of discharged ash.

(2) Multi-layer coupled gasification, in the upper space A (partial pyrolysis zone) of the multi-layer fluidized bed gasification furnace, the waste heat of the catalytic gasification gas is used to heat the newly entered pulverized coal, so that the pulverized coal is partially hot Solving, producing products such as methane gas, increasing the output of decane and tar without increasing energy consumption; in the intermediate space B (catalytic gasification zone), the high temperature vapor generated by coal in the catalyst and residue gasification zone The main reaction of catalytic gasification occurs under the action of generating a bismuth-rich gas and residual residue; in the lower space C (residue gasification zone), a small amount of oxygen is introduced into the gasification agent to vaporize the remaining residue, and the remaining residue is passed through The combustion and gasification of the residue provides the heat required for the catalytic gasification of the intermediate layer space B (catalytic gasification zone) while providing hydrogen and CO which are beneficial to the catalytic gasification reaction.

(3) Compared with the two-step method for preparing methane, the device integrates three reactors of coal pyrolysis, coal catalytic gasification and residue gasification to realize logistics coupling and heat coupling, and self-supply heat to reduce the energy consumption of superheated steam. The problem of carbon residue in the residue is solved; the average residence time is prolonged, the gas production capacity is increased, and the carbon conversion rate is increased. (4) From the whole process, the gasification of the multi-layer fluidized bed gasification furnace is used to prepare a gas rich in decane gas, which has high thermal efficiency, high solid phase processing depth, high decane content in the gas product, and simple equipment. Easy to operate.

(5) The uppermost layer of the multi-layer bed will inhibit the formation of tar to promote the formation of tar, reduce the amount of catalyst, and reduce the cost of the catalyst; at the same time, some industrial wastes (such as black liquor of paper mills, industrial waste alkali, etc.) can be utilized as catalyst raw materials. , increase methane content.

(6) Since the distance between the upper end of each overflow device and the inner wall of the gasifier housing is large (the shortest distance between the upper end inlet and the inner wall of the gasifier housing is in the inner diameter of the gasifier housing) 1/5 times to 1/2 times), the problem of "slow material flow, formation of retention and fluidized dead zone" can be avoided, and at the same time, since the upper and lower outlets of each overflow device are perpendicular to the gasifier The projections of the horizontal plane of the longitudinal axis of the housing are spaced apart from one another (e.g., each overflow device is in the form of a partial inclined tube), such that, for example, between the lower outlet of the first overflow device and the upper inlet of the second overflow device The lateral distance is maximized, so that the length of the lateral flow path of the material in each layer space is extended as much as possible, which can promote the fluidization reaction of the material to be more fully performed, thereby effectively improving the overall efficiency of the fluidized bed. DRAWINGS

Figure 1 is a structural view of an embodiment of the present invention;

2, 3, and 4 are structural views of other embodiments of the present invention, respectively.

Figure 5 is a schematic structural view of various variations of the overflow device of the present invention, wherein Figure 5a is a simplified illustration of the arrangement of the vertically arranged overflow devices of Figures 1-4, and Figure 5b The arrangement of the overflow device in Figure 5c is a more advantageous and preferred manner. detailed description As shown in the accompanying drawings, the present invention provides a multi-layer fluidized bed gasification furnace for gasification of coal to produce a gas rich in decane gas, the fluidized bed gasification furnace comprising:

a gasifier housing 3 having a vertical longitudinal axis defining an interior space therein;

At least two layers of gas distributors 2 in the form of orifice plates arranged in the interior space of the housing 3 perpendicular to the longitudinal axis and at different heights along the longitudinal axis, the at least two layers The gas distributor 2 includes a first gas distributor and a second gas distributor located below the first distributor, the first gas distributor and the second distributor to the inner space of the casing Separated into upper space A, intermediate space B and lower space C;

a raw material inlet 4 disposed at an upper portion of the side of the casing, the raw material inlet leading to the upper space A for inputting raw materials into the upper space A, the overall flow direction of the raw material being along the longitudinal axis Top down

a ash outlet 7 located at the bottom of the casing 3;

a gasifying agent inlet for gasifying agent entering near a side of the ash outlet 7 at the bottom of the casing, the overall flow direction of the gasifying agent being bottom-up along the longitudinal axis;

a gas outlet located at the top of the casing 3;

In the various figures of the present invention, the overflow device is generally indicated by the numeral 1, wherein the overflow device located above is referred to as a first overflow device, and the overflow device located below is referred to as a second overflow device. a first overflow device having a tubular form open at both ends is disposed through the first gas distributor, and the second gas distributor is provided with a second overflow device having a tubular form open at both ends. An overflow device and a second overflow device for flowing the raw material from top to bottom along a tortuous line, flowing from the upper space A through the first overflow device to the intermediate layer space B, and then The intermediate layer space B flows into the lower space C through the second overflow device, and the lower end of the first overflow device and the upper end of the second overflow device are perpendicular to the The longitudinal axes are spaced apart from each other in the horizontal direction to prevent the material from passing straight down.

As shown in FIG. 5b and FIG. 5c, in a preferred embodiment of the present invention, the shortest distance between the upper end of the first overflow device and the inner wall of the gasifier housing is in the gasifier housing. The inner diameter is between 1/5 and 1/2 times, and the shortest distance between the upper end of the second overflow device and the inner wall of the gasifier housing is 1 in the inner diameter of the gasifier housing Between /5 and 1/2 times. Each of the shortest distances exemplarily shown in Figure 5b is about 1/3 times the inner diameter of the gasifier housing, while the shortest distances exemplarily shown in Figure 5c are the inner diameter of the gasifier housing. About 1/2 times. The shortest distance suitable for use in the present invention is that the ratio of the inner diameter of the gasifier housing can vary from 1/2 to 1/5 times both inclusive.

In Fig. 5a, the spacing between each of the overflow means and the inner wall of the gasifier housing is small, such that the respective overflow means are spaced apart from each other in a horizontal direction perpendicular to the longitudinal axis. Larger distances are advantageous in terms of preventing material flow shorts and promoting sufficient reaction of the material. However, each overflow device is adjacent to the inner wall of the gasifier housing (in other words, the distance between the upper end inlet of the overflow device and the inner wall of the housing is too close) during the fluidization process due to all areas on the gas distributor The material flows toward the upper inlet of the overflow device on the gas distributor, in a partial region between the upper inlet of the overflow device and the inner wall of the gasifier housing, due to the overflow device and the gasifier shell The space between the inner walls is narrow, and the resistance formed is larger than other regions, so that the gas short circuit does not flow therethrough, so that the flow of the material in the partial region tends to be slow, causing the flow to stagnant to form a fluidized dead zone. This is obviously unfavorable for the overall efficiency of the fluidized bed, and even causes an unfavorable situation such as coking and blockage of the distributor. For example, in a fluidized bed gasifier of a typical specification, the shortest distance between the upper end of each overflow device and the inner wall of the gasifier housing is 1/5 times the inner diameter of the gasifier housing ( At the critical point), the flow of the material tends to be slow and tends to form a fluidized dead zone. When the shortest distance is less than 1/5 times the inner diameter of the gasifier casing, the fluidized dead zone is clearly formed. With the arrangement of the overflow devices of Figures 5b and 5c, the spacing between the upper end of each overflow device and the inner wall of the gasifier housing is greater, rather than in the immediate vicinity of the gasifier housing as in Figure 5a. The inner wall (that is, the shortest distance is less than 1/5 times the inner diameter of the gasifier shell), so that the problem of "slow material flow, formation of retention and fluidized dead zone" can be avoided, thereby effectively increasing the flow. The overall efficiency of the chemical bed. In a preferred embodiment of the invention, the projections of the upper and lower outlets of the first overflow device on a horizontal plane perpendicular to the longitudinal axis are spaced apart from one another. In a preferred embodiment of the present invention, the first overflow device has an angle formed with the longitudinal axis that is greater than or equal to an angle of repose of the coal material. Further, in a preferred embodiment of the present invention, the first overflow device includes an upper section and a lower section, and an upper section of the first overflow device is parallel to the longitudinal axis, and a lower section of the first overflow device Forming less than or equal to 60 with the longitudinal axis. The angle between the lower portion of the first overflow device and the longitudinal axis preferably forms an angle of between 30 and 50, most preferably 45. Angle of inclusion (the angle of repose of coal raw materials varies according to environmental factors such as coal particle size, temperature, humidity and pressure. In actual production, the parameters of various factors in real coal gasification are used to determine coal under real gasification conditions. The angle of repose, and the range of the angle is greater than or equal to the angle of repose of the coal under real gasification conditions to select the range of the angle), between the upper and lower sections of the first overflow device The arc transitions are connected.

In a preferred embodiment of the invention, the projections of the upper and lower outlets of the second overflow device on a horizontal plane perpendicular to the longitudinal axis are spaced apart from one another. In a preferred embodiment of the invention, the angle between the second overflow device and the longitudinal axis is greater than or equal to the angle of repose of the coal material. Furthermore, in a preferred embodiment of the present invention, the second overflow device includes an upper section and a lower section, an upper section of the second overflow device is parallel to the longitudinal axis, and a lower section of the second overflow device Forming less than or equal to 60 with the longitudinal axis. The angle between the lower section of the second overflow device and the longitudinal axis is preferably 30. To 50. Angle, most preferred shape Into 45. Angle of inclusion (the angle of repose of coal raw materials varies according to environmental factors such as coal particle size, temperature, humidity and pressure. In actual production, the parameters of various factors in real coal gasification are used to determine coal under real gasification conditions. The angle of repose, and the range of the angle is greater than or equal to the angle of repose of the coal under real gasification conditions to select the range of the angle), between the upper and lower sections of the second overflow device The arc transitions are connected.

For example, in the configuration shown in Figure 5b, the upper sections of the first overflow means and the second overflow means are each parallel to the longitudinal axis and the lower sections form an angle of about 45 with the longitudinal axis. And both are inclined toward the left side of the figure. In the configuration shown in Figure 5c, the upper sections of the first overflow means and the second overflow means are both parallel to the longitudinal axis, and the angles formed by the lower sections and the longitudinal axis are about 45 degrees, but the lower sections are respectively oriented. Tilt left and right. It can be seen that in Figures 5b and 5c, the lower end of the first overflow device and the upper end of the second overflow device are spaced apart from each other in a horizontal direction perpendicular to the longitudinal axis, thereby avoiding material straight-through. Further, the projections of the upper end inlet and the lower end outlet of the first overflow device are horizontally spaced apart from each other on a horizontal plane perpendicular to the longitudinal axis, and the upper end inlet and the lower end outlet of the second overflow device are perpendicular to the longitudinal axis The projections on the horizontal plane are spaced apart from each other. These structural settings prevent the material from being short-circuited and promote the material's full response while preventing material retention, thus ensuring smooth and efficient fluidization.

In addition, depending on the characteristics or needs of the actual process conditions, each overflow device can also simply take the form of an integral inclined tube, that is, the upper and lower sections are in a straight line, which is perpendicular to the longitudinal axis of the gasifier housing. Various angles within the above-mentioned angle range are formed. In a preferred embodiment of the invention, the first overflow means of the upper and lower sections in a straight line is in the form of an integral inclined tube which forms a clamp with the longitudinal axis of less than or equal to 60°. angle. In addition, in a preferred embodiment of the present invention, the second overflow device of the upper and lower sections in a straight line takes the form of an integral inclined tube, and the integral inclined tube forms less than the longitudinal axis. Or equal to 60. The angle of the. In this case, it is also possible to satisfy the condition that the projections of the upper end inlet and the lower end outlet of the overflow device are spaced apart from each other on the horizontal plane perpendicular to the longitudinal axis" and achieve the technical effect thereof.

At the lower end of each overflow device, the descending material has a certain velocity and does not form a material retention in the overflow device. Furthermore, the shortest distance between the lower end outlet of each overflow device and the inner wall of the gasifier housing is between 1/10 and 1/6 times the inner diameter of the gasifier, that is, Maintaining a sufficient distance from the nearest inner wall ensures that the particles are flowing there (for example, in Figure 5b, the shortest distance between the lower end outlet of the first overflow means and the inner wall is 1/1 of the inner diameter of the gasifier) 10 times), and therefore, does not tend to form a hold. At the same time, the lower end outlet of each overflow device is kept at a certain distance from the upper end inlet of the next overflow device, as shown in FIG. 5b and FIG. 5c, so as to extend the lower end outlet and the second overflow of the first overflow device as much as possible. The length of the lateral flow path of the material between the upper inlets of the flow device is intended to promote sufficient reaction of the material.

In addition, in practice, when specific arrangements are made for the specific location of each overflow device according to specific process requirements, other aspects of the gasifier are also considered. For example, in Figures 1 to 4, the raw coal inlet The number of inlets of the raw coal loaded with the catalyst may be different. The arrangement and manner of the particular overflow arrangement in Figures 5b and 5c can be optimized in conjunction with the gasifier shown in Figures 1 through 4 and other gasifiers not shown. For example, the inlets of the raw coal inlet 4 and the raw coal loaded with catalyst shown in Fig. 1 are respectively located on both sides of the gasification furnace, but in practice, the two inlets may also be disposed on the same side of the gasification furnace and in the week. The upward position is in the same position, in which case the specific arrangement of the two-layer overflow device of Figure 1 can take the specific position and form of Figure 5b. This arrangement allows the arrangement of the overflow means in each layer to more conveniently balance both the prevention of "material retention - fluidized dead zone" and the extension of the length of the lateral flow path of the material.

As shown in Figures 5b and 5c, there is a gap between the upper and lower sections of each layer of the overflow device. The arc transition segment, the radius of curvature of the arc transition segment can be set according to specific design conditions and can be varied within a reasonable range.

Further, in a preferred embodiment of the present invention, each of the overflow devices may be generally tubular, the upper portion of the overflow device may have a circular cross section, and the lower portion of the overflow device may have an elliptical cross section. As seen from the top view, the long axis of the ellipse should be consistent with the direction of extension of the lower section to maximize the flow section of the material along the extension direction, and the inner diameter of the elliptical short axis should be the same as the circular cross section of the upper section. ), and the arc transition between the upper and lower sections is a reducer joint pipe, so that the circular cross section of the upper section and the elliptical cross section of the lower section naturally transition smoothly, so that the flow resistance of the material in each section minimize.

Further, the lengths of the upper and lower sections of each overflow device may be designed such that the length of the upper section is smaller than the length of the lower section, specifically, the length of the upper section may be 0.2 to 0.6 times the axial projection length of the lower section. The curvature of the arc transition between the upper and lower sections of each overflow device may be determined based on the effective cross-sectional area of the overflow device and the specific length ratio between the upper and lower segments described above.

In a preferred embodiment of the invention, the longitudinal middle portion of the housing is also provided with an auxiliary central feed opening 4.

In a preferred embodiment of the invention, the longitudinal lower portion of the housing is further provided with an auxiliary lower feed opening 5 (see Fig. 2).

In a preferred embodiment of the present invention, at least one layer of gas distributor for further separating the space is provided in any one of the upper space A, the intermediate space B, and the lower space C. An overflow device arranged by the at least one gas distributor.

In a preferred embodiment of the invention, the third gas distributor is funnel shaped (see Figure 3). Referring to Fig. 1, the present invention provides a gasification apparatus which can be applied to a multi-layer fluidized bed coal gasification to obtain a methane-rich gas system, which is a multi-layer fluidized bed gasification furnace, comprising: an upper space A ( Partial pyrolysis zone), intermediate zone space B (catalytic gasification zone), lower zone space C (residual gasification zone).

The raw coal enters the upper space A through the feed port 4 of the multi-layer fluidized bed space A, that is, the partial pyrolysis zone. In the partial pyrolysis zone, the feed cold coal powder is heated by the high temperature hot gas generated by the lower end reaction, so that partial pyrolysis occurs. Pyrolysis of raw coal produces pyrolysis gas, tar and semi-coke rich in methane. The gaseous catalyst entering the upper space A (partial pyrolysis zone) changes its form due to the decrease of temperature, separates from the gas product, and remains in the furnace to continue to participate in the gasification reaction to realize the recycling of the catalyst in the furnace.

The mixture of coal and catalyst enters the intermediate layer space B through the feed port 4 of the intermediate layer space B, that is, the catalytic gasification zone of the gasifier, where the mixture of coal and catalyst passes from the upper space A through the overflow device 1 The partially pyrolyzed coal powder is mixed and gasified with a gasifying agent by a catalyst to form an effective gas component such as CH ₄ , CO, H ₂ , C0 ₂ , a small amount of H ₂ S and NH _{3 ,} and the like. The main reactions are as follows:

2C + 2H ₂ 0→ 2H ₂ + 2CO (1)

CO + H ₂ 0→ C0 ₂ + H ₂ (2)

3H ₂ + CO→ CH ₄ + H ₂ 0 (3)

C + 2H ₂ → CH ₄ (4) The lower space C (residue gasification zone) CO and H ₂ can enter the intermediate space B (catalytic gasification zone), methanation reaction occurs under the action of the catalyst, and the system is increased. The methane yield, in addition, the high-temperature steam generated in the lower space C (residue gasification zone) provides the heat required for partial reaction in the intermediate space B (catalytic gasification zone). The coal residue which is not sufficiently reacted in the intermediate layer space B (catalytic gasification zone) enters the lower space C (residue gasification zone), and is gasified by the action of 0 ₂ and steam to generate gases such as CO, H ₂ and C0 ₂ . The main reactions are as follows: c + o ₂ → co ₂ (5)

C + C0 ₂ → 2CO (6)

C + H ₂ 0→ CO + H; (7)

CO + H ₂ 0→ CO, + (8) As described above, CO and H ₂ generated in the lower space C (residue gasification zone) of the gasifier can enter the upper intermediate space B (catalytic gasification zone), The methanation reaction occurs under the action of the catalyst, thereby increasing the system decane yield. In addition, the generated high temperature gas and water vapor can provide partial heat to the intermediate layer space B (catalytic gasification zone), thereby reducing the ash. The slag carbon content, and improve the comprehensive utilization of feed pulverized coal.

The higher temperature in the lower space C (residual gasification zone) causes some of the catalyst to volatilize in the gaseous form to the intermediate layer space B (catalytic gasification zone), and the recycling of the catalyst in the fluidized bed can reduce the catalyst in the initial pulverized coal. The amount of addition in the catalyst reduces the burden on the catalyst recovery system, even without the need to additionally configure a catalyst recovery system.

The gasification agent superheated steam and a small amount of oxygen enter the residue gasification zone from the bottom of the gasifier, and burn and gasify with the residue, while providing the required heat to the intermediate space B (catalytic gasification zone).

A slagging device is connected below the multi-layer fluidized bed gasification furnace, and the slagging device is used to discharge the ash after gasification in the gasification zone of the residue.

The high-temperature furnace gas produced by the multi-layer fluidized bed gasification furnace is discharged from the top of the furnace and enters the subsequent separation and purification process. As described above, the gasification furnace outlet gas (high-temperature furnace gas) passes through the isothermal dust filter unit, and the filtered dust is returned to the gasification furnace to continue the gasification reaction, and the filtered gas is sent to the gas-liquid cooling separation unit. Gas-liquid separation To low temperature tar and crude gas. Thereafter, the crude gas enters the gas purifying device to remove acid gases such as carbon dioxide and hydrogen sulfide, thereby obtaining a gas rich in decane.

Example 1:

Referring to Fig. 2, on the basis of the structure of Fig. 1, if the heat generated by the gasification of the residue alone is difficult to meet the temperature requirements for the catalytic gasification, the furnace in the lower space C (residue gasification zone) of the multilayer fluidized bed can be used. A feed port 5 is disposed on the side wall of the body 3, and a small amount of raw coal is supplied to the residue gasification zone through the feed port, and the combustion of the small amount of raw coal in the lower space C (residue gasification zone) can provide auxiliary energy to satisfy The temperature requirements required for catalytic gasification.

Example 2:

Referring to Figure 3, on the basis of the structure of Figure 1, in order to meet the requirements of ash discharge or process operating conditions, the distributor of the lower fluidized bed lower space C can be replaced, using a funnel-shaped distributor through the air inlets 6, 7 The ash discharge gas velocity and the fluidization gas velocity are separately regulated.

Example 3:

Referring to Figure 4, on the basis of the structure of Figure 1, in order to avoid the reverse flow of gas, to achieve a continuous and stable overflow between the beds, and at the same time to facilitate the control of the overflow flow of the material, other forms of overflow devices can be used, such as with mechanical transmission Plug-type overflow device for the device. The position of the plug 8 is adjusted by a mechanical transmission to change the direction of the gas and the cross-section of the lower opening to achieve a smooth overflow.

In the various embodiments shown in connection with Figures 1-4 and described above, the scale setting in the figure can be modified (that is, the modified scale setting is different from that shown in Figure 1-4. a ratio such that the shortest distance between the upper end of the first overflow device and the inner wall of the gasifier housing is between 1/5 and 1/2 times the inner diameter of the gasifier housing, and the second overflow The shortest distance between the upper end of the flow device and the inner wall of the gasifier housing is between 1/5 and 1/2 times the inner diameter of the gasifier housing.

Example 4:

Referring to Figure 5b, the arrangement of the overflow device is modified and optimized based on the previous embodiments. In the configuration shown in Figure 5b, the first overflow device located above The shortest distance between the upper end of the gasifier and the inner wall of the gasifier housing is between 1/5 and 1/2 times the inner diameter of the gasifier shell, and the upper end of the second overflow device located below is gas The shortest distance between the inner walls of the furnace shell is between 1/5 and 1/2 times the inner diameter of the gasifier shell. Each of the shortest distances exemplarily shown in Figure 5b is about 1/3 times the inner diameter of the gasifier housing. In the configuration shown in Figure 5b, the upper sections of the first overflow means and the second overflow means are both parallel to the longitudinal axis, and the lower sections form an angle of about 45 with the longitudinal axis and are oriented toward the left side of the figure. The direction is tilted.

Example 5

Referring to Figure 5c, the arrangement of the overflow device is improved and optimized based on the previous embodiments. In the configuration shown in Figure 5c, the shortest distance between the upper end of the first overflow device and the inner wall of the gasifier housing is 1/5 to 1/2 of the inner diameter of the gasifier housing. Between times, and the shortest distance between the upper end of the second overflow device located below and the inner wall of the gasifier housing is between 1/5 and 1/2 times the inner diameter of the gasifier housing. Each of the shortest distances exemplarily shown in Figure 5c is about 1/2 times the inner diameter of the gasifier housing. In the configuration shown in Figure 5c, the upper sections of the first overflow means and the second overflow means are each parallel to the longitudinal axis, and the lower sections form an angle of about 45 with the longitudinal axis. However, each lower section is inclined toward the left and right sides of the figure.

In various embodiments of the present invention, a plug-type overflow device with a mechanical transmission as shown in Figure 4 can be used in combination as needed.

In various embodiments of the invention, the height of the weir (the portion of the overflow device above the gas distributor) is determined by the solid phase processing time and the bed holding amount, using the following formula

T—the solid phase processing time of this layer, the unit is h

D—the inner diameter of the furnace body, in m The density of the bed under operating conditions, in kg/m ³

s - porosity of the bed under operating conditions

In various embodiments of the invention, the distance between two adjacent gas distributors is determined by the height of the overflow device between them and the height of the bed holding capacity, calculated by:

among them

H -... the distance between two adjacent gas distributors, in units of m;

The core technical points of the invention:

1. Integration of multi-layer fluidized bed: The gasification agent is introduced from the bottom of the gasification furnace. The raw coal is added from the upper pyrolysis section of the reactor and passes through the upper space A of the multi-layer fluidized bed, the intermediate layer space B, and the lower layer. Space (:. In the upper space A (partial pyrolysis zone) of the multi-layer fluidized bed, the high temperature heat generated by the catalytic gasification reaction of the feed cold coal powder in the intermediate layer space B (catalytic gasification zone) The gas is heated to partially pyrolyze the pulverized coal to form a pyrolysis gas rich in CH ₄ and a product such as tar. Thereafter, the partially pyrolyzed coal powder passes through the first overflow device and enters the multi-layer fluidized bed. The intermediate layer space B (catalytic gasification zone) undergoes catalytic gasification, methanation and the like under the action of a catalyst to generate effective gas components such as CH ₄ , CO, H ₂ and C0 ₂ , a small amount of H ₂ S and NH. _3, etc. Then, the coal residue that is not sufficiently reacted in the intermediate space B (catalytic gasification zone) enters the lower space C (residue gasification zone) of the multi-layer fluidized bed through the second overflow device, at 0 ₂ Gasification under the action of water vapor to generate gases such as CO, H ₂ and C0 ₂ .

2. The close relationship between the lower layer space C of the multi-layer fluidized bed and the intermediate layer space B: 10 001410

The lower space C (residue gasification zone) of the multi-layer fluidized bed, the residue reacts with oxygen to generate a large amount of heat, and provides the required heat for the intermediate layer space B (catalytic gasification section), thereby reducing the ash carbon content, and Increasing the comprehensive utilization rate of the feed coal powder; meanwhile, in the lower space C (residue gasification zone), some of the catalyst is volatilized in a gaseous form to the intermediate layer space B (catalytic gasification zone) of the multi-layer fluidized bed, thereby The recycling of the catalyst in the fluidized bed is achieved. The effect of this recycling of the catalyst in the fluidized bed is: it can reduce the amount of catalyst added in the initial pulverized coal, reduce the burden on the catalyst recovery system, and even eliminate the need to additionally arrange a catalyst recovery system; in the gasification zone of the gasifier residue (multilayer The CO and H ₂ produced in the fluidized bed lower space C) can enter the multi-layer fluidized bed intermediate layer space B (catalytic gasification zone), and the decaneization reaction occurs under the action of the catalyst, thereby increasing the system decane production. In addition, the generated high-temperature steam can provide partial heat to the catalytic gasification zone, thereby reducing the ash carbon content and improving the comprehensive utilization of the feed coal powder.

3. Selection of feed port of multi-layer fluidized bed: According to the needs of system heat balance and process operation conditions, except for the uppermost feed port of the multi-layer fluidized bed, the middle layer and the lowermost furnace body 3 may be different. Add a feed port at the location.

4. Number of layers of multi-layer bed: Partial pyrolysis zone, catalytic gasification zone and residue gasification zone of multi-layer fluidized bed gasifier can be divided into single layers according to the residence time and process operation conditions. Or multiple layers, each layer is separated by a gas distributor, and an overflow device is installed.

5. The shortest distance between the upper end of each overflow device and the inner wall of the gasifier housing is between 1/5 and 1/2 times the inner diameter of the gasifier housing. Each overflow device may be a mechanical overflow device, such as a plug or valve at the lower end of the overflow device, or a pneumatically controlled overflow device such as a straight tube, a conical tube, or an L-shaped valve. In a preferred form of the invention, the projections of the upper and lower end outlets of each of the overflow devices are spaced apart from each other on a horizontal plane perpendicular to the longitudinal axis. In a further preferred mode of the present invention, each of the overflow devices includes an upper section and a lower section, the upper section being parallel to the longitudinal axis, and the lower section and the longitudinal axis being shaped It is less than or equal to 60. The angle between the upper section and the lower section is connected by a circular transition section.

6. Gas distributor: The gas distributor of each of the overflow devices in the upper portion of the multi-layer fluidized bed may be a plate distributor, a tilt distributor or a funnel-shaped distributor, or a combination thereof. The gas distributor 2 at the lower gas inlet of the multi-layer fluidized bed may be a flat plate distributor, a tilt distributor, a funnel-shaped distributor, or a gas distributor with a jet.

7. The multi-layer fluidized bed gasifier can be used under normal pressure and pressure.

Technical problems and beneficial effects solved by the present invention

The object of the present invention is to provide a multi-layer fluidized bed gasification furnace which is rich in decane gas by powder coal gasification, and the gasification furnace realizes continuous stable overflow between layers of fluidized bed through an overflow device, Pyrolysis, gasification, and combustion are coupled into a multi-layer fluidized bed to achieve fractional conversion, and energy distribution is performed centering on catalytic gasification and methane production to realize full-price development of coal resources.

First, in a (first-stage) fluidized bed, the solid phase residence time is extended, the carbon conversion rate is maximized, the equipment investment is reduced, and the operation is easy, as compared with the multi-stage fluidized bed of U.S. Patent 4,077,778;

Secondly, compared with the devices in other patents, the gasification reaction through the residue gasification zone of the lower bed space C of the multilayer bed supplies hydrogen and carbon monoxide to the catalytic gasification zone of the intermediate layer space layer B, thereby promoting the methanation reaction. There is no need for a gas separation system for separating hydrogen and carbon monoxide, which can greatly reduce equipment investment and simplify operation; at the same time, a gasification agent and a small amount of oxygen are introduced into the lower layer space C of the multilayer bed to burn part of the residue, and the catalytic gas to the intermediate layer space B The reaction provides a portion of the heat required for the reaction, which reduces the temperature of the inlet steam, reduces the load on the steam superheat system and the heat exchange system, and also solves the problem of carbon residue in the residue.

In addition, the decane generated in the pyrolysis section of the multi-layer bed space A directly escapes from the gasifier, thereby avoiding oxidation and increasing the methane content in the gas phase product, and at the same time, various other products such as tar formation by pyrolysis can be obtained. From a thermal point of view, make the most of it The thermal energy of the gas from the intermediate layer space B has a high thermal efficiency and also brings convenience to the subsequent processing system.

Due to the large spacing between the upper end of each overflow device and the inner wall of the gasifier housing (the shortest distance between the upper end inlet and the inner wall of the gasifier housing is 1/5 of the inner diameter of the gasifier housing) Between 1/2 times and 1/2 times, the problem of "slow material flow, formation of retention and fluidized dead zone" can be avoided. In addition, since the projections of the upper end inlet and the lower end outlet of each overflow device on a horizontal plane perpendicular to the longitudinal axis are spaced apart from each other (for example, each overflow device adopts a partial inclined tube), for example, in the first overflow device The lateral distance between the lower outlet and the upper inlet of the second overflow device is maximized, so that the length of the lateral flow path of the material in each layer space is extended as much as possible, which can promote the fluidization reaction of the material to proceed more Sufficient, thereby effectively improving the overall efficiency of the fluidized bed.

Finally, in terms of catalyst utilization, the uppermost layer of the multi-layer bed will inhibit the formation of tar to promote the formation of tar, reduce the amount of catalyst, and reduce the cost of the catalyst; at the same time, some industrial waste can be used as a catalyst raw material to increase the methane content.

Claims

Rights request

A multi-layer fluidized bed gasification furnace for gasification of coal to produce a gas rich in decane gas, the fluidized bed gasification furnace comprising:

a ash outlet located at the bottom of the housing;

a gas outlet at the top of the housing;

The first gas distributor is provided with a first overflow device in a tubular form open at both ends, and the second gas distributor is provided with a second overflow device in a tubular form with both ends open. The first overflow device and the second overflow device are configured to move the raw material from top to bottom along a tortuous line, and flow from the upper space to the intermediate layer space through the first overflow device, and then The intermediate layer space flows into the lower space through the second overflow device,

a lower end outlet of the first overflow device and an upper end of the second overflow device The ports are spaced apart from each other in a horizontal direction perpendicular to the longitudinal axis to prevent the material from passing straight down.

2. The multi-layer fluidized bed gasification furnace according to claim 1, wherein a shortest distance between an upper end inlet of the first overflow device and an inner wall of the gasifier housing is gasification The inner diameter of the furnace shell is between 1/5 and 1/2 times, and the shortest distance between the upper end inlet of the second overflow device and the inner wall of the gasifier housing is in the gasifier housing The inner diameter is between 1/5 and 1/2 times the inner diameter.

3. The multi-layer fluidized bed gasification furnace according to claim 2, wherein a shortest distance between an upper end inlet of the first overflow device and an inner wall of the gasifier housing is gasification The inner diameter of the furnace shell is between 1/3 and 1/2 times, and the shortest distance between the upper end inlet of the second overflow device and the inner wall of the gasifier housing is in the gasifier housing The inner diameter is between 1/3 and 1/2 times.

The multi-layer fluidized bed gasification furnace according to claim 2, wherein the projections of the upper end inlet and the lower end outlet of the first overflow device are horizontally spaced apart from each other on a horizontal plane perpendicular to the longitudinal axis .

The multi-layer fluidized bed gasification furnace according to claim 4, wherein the first overflow means has an angle formed with the longitudinal axis that is greater than or equal to an angle of repose of the coal material.

6. The multi-layer fluidized bed gasifier of claim 4, wherein the first overflow device forms less than or equal to 60 with the longitudinal axis. The angle of the.

The multi-layer fluidized bed gasification furnace according to claim 4, wherein the first overflow device comprises an upper section and a lower section, and an upper section of the first overflow device is parallel to the longitudinal axis, The angle between the lower portion of the first overflow device and the longitudinal axis is greater than or equal to the angle of repose of the coal material, and the upper and lower portions of the first overflow device are connected by a circular arc transition.

The multi-layer fluidized bed gasification furnace according to claim 4, wherein the first overflow device comprises an upper section and a lower section, and an upper section of the first overflow device The longitudinal axis is parallel, and the lower section of the first overflow device forms less than or equal to 60 with the longitudinal axis. The angle between the upper section and the lower section of the first overflow device is connected by a circular arc transition section.

The multi-layer fluidized bed gasifier according to claim 8, wherein the lower portion of the first overflow device forms a 30 to 50 with the longitudinal axis. The angle of the.

10. The multi-layer fluidized bed gasification furnace according to claim 4, wherein a shortest distance between a lower end outlet of the first overflow device and an inner wall of the gasifier housing is 1/ 10 times to 1/6 times.

The multi-layer fluidized bed gasification furnace according to claim 2, wherein the projections of the upper end inlet and the lower end outlet of the second overflow device are horizontally spaced apart from each other on a horizontal plane perpendicular to the longitudinal axis .

The multi-layer fluidized bed gasification furnace according to claim 11, wherein the second overflow means forms an angle with the longitudinal axis that is greater than or equal to an angle of repose of the coal material.

13. The multilayer fluidized bed gasifier of claim 11 wherein said second overflow means forms less than or equal to 60 with said longitudinal axis. The angle of the.

14. The multi-layer fluidized bed gasification furnace of claim 11 wherein: said second overflow means comprises an upper section and a lower section, said upper section of said second overflow means being parallel to said longitudinal axis, The angle between the lower section of the second overflow device and the longitudinal axis is greater than or equal to the angle of repose of the coal material, and the upper and lower sections of the second overflow device are connected by a circular arc transition.

15. The multi-layer fluidized bed gasification furnace according to claim 11, wherein the second overflow device comprises an upper section and a lower section, and an upper section of the second overflow device is parallel to the longitudinal axis, The lower section of the second overflow device forms less than or equal to 60 with the longitudinal axis. The angle between the upper and lower sections of the second overflow device is connected by a circular arc transition.

16. The multilayer fluidized bed gasifier of claim 15 wherein: The lower section of the second overflow device forms a 30 with the longitudinal axis. To 50. The angle of the.

The multi-layer fluidized bed gasification furnace according to claim 1, wherein at least one of a longitudinal middle portion or a longitudinal lower portion of the casing is further provided with an auxiliary feed

The multi-layer fluidized bed gasification furnace according to claim 1, wherein any one of the upper space, the intermediate space and the lower space is further provided for further separating the space. At least one gas distributor and an overflow device disposed through the at least one gas distributor.

The multi-layer fluidized bed gasification furnace according to claim 1, wherein in the casing, a third gas distributor is further disposed below the second gas distributor.

20. The multilayer fluidized bed gasifier of claim 19, wherein the third gas distributor is funnel shaped.

The multilayer fluidized bed gasification furnace according to any one of claims 1 to 20, wherein

The portion of the overflow device above the gas distributor is an overflow weir, and the amount of the weir between the weir and the bed is determined by the following formula:

The overflow height of a particular layer, in m;

W—the amount of solid particles fed in this layer, in units of kg/h;

t --- the solid phase processing time of this layer, the unit is h;

D―—the inner diameter of the furnace body, in m;

P...-the density of the bed under operating conditions, in units of k _g /m ³ ;

s... Porosity of the bed under operating conditions.

The fluidized bed gasification furnace according to any one of claims 1 to 20, wherein

The distance between two adjacent gas distributors is the overflow device between them The height and the height of the bed holding capacity are determined by the following formula:

H=H ₁ +h ₁ -h ₂

among them

H The distance between two adjacent gas distributors, in m;

_Hl - the height of the overflow device between the two gas distributors, the unit is m; h _l ... - the height of the material holding amount between the two gas distributors, the unit is m;