A composite gasification device based on a filtration combustion mode and its gasification method

Abstract

The present invention provides a composite gasification device based on a filtration combustion mode, belonging to the technical field of solid fuel gasification for producing synthesis gas. It solves the problems of low carbon conversion efficiency, high tar content, and low synthesis gas yield. It includes a gasifying agent inlet, a preheating section, a reaction section, a reforming section, a synthesis gas outlet, and a discharging section. The gasifying agent inlet is communicated with the preheating section. Both ends of the reaction section are respectively communicated with the preheating section and the reforming section. The synthesis gas outlet is communicated with the reforming section. The discharging section is communicated with the reaction section. Both the preheating section and the reforming section are composed of various forms of inert porous medium fillers. The internal of the porous medium packed bed has complex pore channels, which is beneficial to mass transfer and heat transfer. The porous medium can be composed of inert particles such as ceramsite or glass microspheres and similar substances, wire meshes, and foam ceramics, etc. It is mainly used for the efficient gasification of various solid fuels.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid fuel gasification for producing syngas, and particularly relates to a composite gasification device based on a filtration combustion mode and a gasification method thereof. Background Art

[0002] As an important part of the efficient and clean utilization of solid fuels, the gasification technology of solid fuels has the advantages of environmental friendliness, strong flexibility and high economy. It is the industrial foundation for the production of synthetic natural gas, hydrogen production and solid fuel-based chemical products, etc., and has been favored by many researchers. At present, the types of gasifiers mainly include fixed beds, fluidized beds and entrained flow beds, etc. According to the different gasification raw materials and application principles, the above three furnace types have their own technical characteristics and application scenarios. Practical engineering applications show that there are various types of solid fuels, and for some solid fuels with complex and variable components such as organic solid waste, etc., the traditional gasification technology has poor adaptability to them, and there are problems such as low carbon conversion efficiency, high tar content and easy damage of gasification equipment. Improving the syngas yield and reducing the tar content have always been the main directions for the development of syngas production from solid fuels. At present, catalytic cracking and plasma gasification technologies are usually used to improve the gasification efficiency of solid fuels and reduce the pollutant emission concentration, but problems such as reducing the carbon content in ash, controlling the tar content and improving the raw material adaptability still need to be solved, and the gasification cost needs to be further reduced. Therefore, developing an efficient gasification device applicable to various solid fuels that can solve the above problems simultaneously is crucial for realizing the clean utilization of solid fuels. Summary of the Invention

[0003] In view of this, the present invention aims to propose a composite gasification device based on a filtration combustion mode and a gasification method thereof to solve the problems of low carbon conversion efficiency, high tar content and low syngas yield.

[0004] To achieve the above object, the present invention adopts the following technical solutions: A composite gasification device based on a filtration combustion mode, including a gasifying agent inlet, a preheating section, a reaction section, a reforming section, a syngas outlet and a discharging section. The gasifying agent inlet is communicated with the preheating section, both ends of the reaction section are respectively communicated with the preheating section and the reforming section, the syngas outlet is communicated with the reforming section, the discharging section is communicated with the reaction section. Both the preheating section and the reforming section are composed of various forms of inert porous medium fillers. There are complex pore channels inside the porous medium packed bed layer, which is beneficial to mass transfer and heat transfer. The porous medium can be composed of inert particles such as ceramsite or glass microspheres and similar substances, wire meshes and foam ceramics, etc. Part of the heat of the preheating section comes from the heat transferred by the combustion of the reaction section materials, and the other part comes from the physical sensible heat of the high-temperature ash in the central discharging pipe or the heat generated by the combustion of the residual carbon therein. The reforming section can be arranged in multiple layers according to requirements.

[0005] Further, the reaction section includes a feed inlet, a reaction zone, and a discharge pipe. The feed inlet is in communication with the reaction zone. One end of the discharge pipe is in communication with the lower end of the reaction zone, and the other end of the feed pipe is in communication with the discharge section. Both ends of the reaction zone are respectively in communication with the preheating section and the reforming section.

[0006] Further, the discharge section includes a discharge valve and a discharge outlet. The discharge outlet is in communication with the discharge pipe, and a discharge valve is provided on the discharge pipe.

[0007] Further, an isobaric air chamber is provided between the gasifying agent inlet and the preheating section. The isobaric air chamber adopts a single-side air inlet mode and is similar to a pipe tobacco in shape.

[0008] Further, the reaction zone is a conical section with an inclination angle close to the angle of repose of the material. The lower boundary of the reaction zone is a conical air distribution plate, and the upper boundary of the reaction zone is a conical perforated plate. The conical air distribution plate and the conical perforated plate are arranged in parallel. The inclination angle of the conical air distribution plate is close to the angle of repose at which the material freely slides or rolls. The material can slide or roll downward along the conical air distribution plate. The inclination angle of the conical perforated plate can vary within the range of the angle of repose ±10°.

[0009] Further, the discharge pipe is made of ceramics or heat-resistant materials.

[0010] Further, a discharge air chamber is communicated with the discharge pipe, and a discharge air inlet is communicated with the discharge air chamber.

[0011] Further, a loosening air chamber is communicated with the discharge pipe. The loosening air chamber is connected to the discharge air chamber, and a loosening air inlet is communicated with the loosening air chamber.

[0012] Further, a first perforated flow equalizing plate is provided between the isobaric air chamber and the preheating section.

[0013] Further, a second perforated flow equalizing plate is provided at the connection between the loosening air chamber and the discharge pipe.

[0014] A gasification method for a composite gasification device based on a filtration combustion mode includes the following steps:

[0015] Step 1: Prepare the gasification raw material. Crush the solid fuel into appropriate particles. After simple drying treatment to make the moisture content meet the requirements, mix it evenly with inert bed material as the gasification raw material, where the particle size of the inert bed material particles is not greater than the average particle size of the fixed fuel particles.

[0016] Step 2: First, use a flammable substance gasifier to ignite the gasifier and preheat it to an appropriate temperature. Then, replace the flammable substance with gasification raw materials. Adjust the switching of the three operating modes of the gasifier by regulating the matching relationship between the flow rate of the gasifying agent and the feeding speed. When the flow rate of the inlet gasifying agent flowing through the preheating section is small, it corresponds to the moving bed mode. The gasification raw materials in the combustion area gradually move downward layer by layer and react layer by layer. Increase the flow rate of the inlet gasifying agent flowing through the preheating section to make the gasification raw material particles fluidize and transform into the fluidized bed mode. Or keep the flow rate of the inlet gasifying agent flowing through the preheating section at a small value, but increase the flow rate of the loosening air flowing through the central discharge pipe to change the operating state to the spouted bed mode. Then, in a specific operating mode, the fixed fuel particles react with the gasifying agent in the reaction zone to complete the gasification process;

[0017] Step 3: The ash generated during the combustion and gasification of the fixed fuel is mixed and heat transferred with the fuel and the inert bed material. In the moving bed operating state, the inert bed material will be discharged from the discharge pipe. In the fluidized bed and spouted bed operating states, the smaller particles further participate in the gasification process in the reaction zone, and the larger particles are discharged from the discharge pipe with the inert bed material. By controlling the gas velocity of the air or gasifying agent in the discharge pipe, the size and flow rate of the falling ash particles are controlled, and a certain bed material height is maintained in the discharge pipe. Those meeting the discharge conditions will be discharged from the discharge port under the action of the discharge air;

[0018] Step 4: When the gasifier stops operating, first stop the input of the gasification raw materials, keep the flow rate of the gasifying agent and the air flow rate at the loosening air inlet unchanged. After the gas raw materials are completely converted, close the delivery of the gasifying agent and the loosening air, discharge all the remaining furnace materials and ash residues, and finally purge it with air once.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. Based on the porous medium filtration combustion mode, the present invention can effectively improve the temperature distribution uniformity and energy utilization efficiency of the gasification system, which is helpful for realizing combustion and ultra-adiabatic gasification. It can not only adopt the optimal gasifier type according to the physical and chemical properties of the gasification raw materials to achieve the efficient gasification of various solid fuels; but also can flexibly adjust the operating mode of the gasifier by regulating the matching relationship between the flow rate of the gasifying agent and the feeding speed according to the quality requirements of the syngas during the gasification operation. Compared with other solid fuel gasification technologies, the composite gasification technology based on the filtration combustion mode of the present invention has dual fuel adaptability;

[0021] 2. Compared with other solid fuel gasification devices, the reforming section of the composite gasification device based on the filtration combustion mode in the present invention can not only further crack the syngas generated by the gasification reaction under high-temperature conditions, but also conveniently load catalysts. In the presence of catalysts, the macromolecular substances in the gasification products can be further catalytically reformed, which can not only reduce the tar content in the gasification products, but also regulate the concentration distribution of each component in the syngas and increase the concentration of H2 in the syngas;

[0022] 3. For the composite gasification device based on the filtration combustion mode in the present invention, the porous medium packing beds in the preheating section and the reforming section have complex and variable channels, which can enhance the heat transfer, mass transfer and transverse mixing of the gas flow. At the same time, due to the dispersion effect of the porous medium, the temperature distribution of the gasification system is more uniform, without local high temperature. The gasifying agent can be effectively preheated, and the adaptability of the gasification system to the changes in the moisture content, ash content and calorific value of the gasification raw materials can be improved;

[0023] 4. The slag discharge system of the present invention adopts a combined connection of a discharge pipe and a discharge valve. Compared with other solid fuel gasification devices, the gasification device of the present invention can flexibly regulate the height of the ash slag bed and the particle size of the ash particles by changing the flow rate of the loosening air. The ash slag accumulated in the discharge pipe can fully heat the preheating section, extend the residence time of the ash slag, and effectively recover the waste heat in the ash slag; in addition, the unburned carbon in the ash slag can further react along the falling path of the discharge pipe until the reaction is complete, which can reduce the carbon content in the ash slag and further improve the gasification efficiency, and has higher engineering practice value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0025] Figure 1 is a schematic structural diagram of a composite gasification device based on the filtration combustion mode according to the present invention;

[0026] Figure 2 is a partially enlarged schematic view of the conical air distribution plate according to the present invention;

[0027] Figure 3 is a partially enlarged schematic view of the first porous uniform flow plate according to the present invention;

[0028] Figure 4 is an internal structural schematic diagram of a composite gasification device based on the filtration combustion mode according to the present invention.

[0029] 1 - Gasifier inlet, 2 - Equal - pressure air chamber, 3 - Pre - heating section, 4 - Reaction zone, 5 - Reforming section, 6 - Discharge valve, 7 - First porous uniform flow plate, 8 - Conical air distribution plate, 9 - Conical porous plate, 10 - Syngas outlet, 11 - Feed inlet, 12 - Discharge pipe, 13 - Second porous uniform flow plate, 14 - Loosening air chamber, 15 - Discharge air chamber, 16 - Loosening air inlet, 17 - Discharge air inlet, 18 - Discharge outlet. Detailed implementation manners

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention may be combined with each other. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0031] See Figures 1-4 This embodiment will be described. A composite gasification device based on a filtration combustion mode includes a gasifier inlet 1, a pre - heating section 3, a reaction section, a reforming section 5, a syngas outlet 10, and a discharge section. The reaction section includes a feed inlet 11, a reaction zone 4, and a discharge pipe 12. The discharge section includes a discharge valve 6 and a discharge outlet 18. The gasifier inlet 1 is communicated with the pre - heating section 3, the feed inlet 11 is communicated with the reaction zone 4, both ends of the reaction zone 4 are respectively communicated with the pre - heating section 3 and the reforming section 5, the syngas outlet 10 is communicated with the reforming section 5, one end of the discharge pipe 12 is communicated with the reaction zone 4, the other end of the discharge pipe 12 is communicated with the discharge outlet 18, and a discharge valve 6 is provided on the discharge pipe 12. In the pre - heating section 3 and the reforming section 5, various media in various forms are freely combined in an orderly or disorderly manner to optimize and improve the efficiency of the gasifier and the quality of the syngas. First, the material enters the reaction zone 4 from the feed inlet 11, and the gasifying agent enters the reaction zone 4 through the pre - heating section 3 via the gasifier inlet 1 and undergoes a gasification reaction with the material in the reaction zone 4. The generated syngas is further cracked and reformed through the reforming section 5 and discharged through the syngas outlet 10. Then, the ash residue after the reaction falls along the discharge pipe 12, and the fuel can further react along the discharge pipe 12 until the reaction is complete. The ash residue meeting the discharge conditions is discharged through the discharge outlet 18.

[0032] By fully preheating the gasifying agent in the preheating section 3, not only can the adaptability of the gasification system to the moisture content, ash content, and calorific value of the fuel be improved, but it also helps the fuel achieve autothermal gasification in the reaction section, maximizing the energy utilization efficiency. Then, the inert bed material filled in the reforming section 5 can further crack the syngas generated by the gasification reaction or catalytically reform the syngas under the condition of loading a catalyst. This can not only reduce the tar content in the gasification products. Additionally, by selecting a suitable catalyst, the concentration of each component in the syngas can be purposefully regulated, increasing the concentration of H2 in the syngas, becoming a hydrogen production technology, and enabling the gasification of solid fuels to produce syngas to have a wider application range.

[0033] Further, an isobaric air chamber 2 is provided between the gasifying agent inlet 1 and the preheating section 3. The isobaric air chamber 2 adopts a single-side air inlet mode, and its outer shape is similar to a tobacco pipe. To a certain extent, this shape is beneficial to reducing the pressure loss. And a first porous flow equalizing plate 7 is provided at the connection between the isobaric air chamber 2 and the preheating section 3. Through the first porous flow equalizing plate 7, the isobaric and uniform distribution of the incoming air can be achieved, avoiding the problems of uneven temperature distribution in the reaction zone and uneven contact between the material and the gasifying agent caused by uneven pressure and flow distribution of the gasifying agent in the radial direction of the preheating section 3.

[0034] Further, the reaction zone 4 adopts a method of distributing air through an inclined conical porous plate. The lower boundary is a conical air distribution plate 8, and the upper boundary is a conical porous plate 9. And the conical air distribution plate 8 and the conical porous plate 9 are arranged in parallel, which can ensure that the residence time of the raw material in the furnace is consistent.

[0035] Further, the discharge pipe 12 is made of ceramics or heat-resistant materials. A discharge valve 6 is also provided on the discharge pipe 12. The discharge is controlled through the discharge valve 6. The ash slag with a relatively high temperature can maintain a certain height in the discharge pipe 12 to preheat the preheating section 3. Moreover, the uncompletely converted carbon in the ash slag can further undergo combustion or gasification reactions in the central pipe, effectively recovering the waste heat in the ash slag and reducing the carbon content in the ash slag. Other forms of discharge valves 6 can also be used in the present invention to achieve the purpose of maintaining a certain material height and completing the discharge function.

[0036] Further, a loosening air chamber 14 is provided below the discharge pipe 12. A loosening air inlet 16 is connected to the loosening air chamber 14. Furthermore, the height of the ash slag accumulation layer in the discharge pipe and the particle size of the ash particles can be controlled by changing the flow rate of the loosening air.

[0037] A gasification method for a composite gasification device based on a filtration combustion mode, which includes the following steps:

[0038] Step 1: Pretreatment of gasification raw materials: After the solid fuel is crushed, control the appropriate particle size and ensure that the moisture content meets the requirements. Then mix it evenly with inert bed material particles as the gasification raw materials, where the particle size of the inert bed material is not greater than the average particle size of the solid fuel particles;

[0039] Step 2: Ignition of the gasifier and gasification of solid fuel: First, the flammable substance for ignition enters the reaction section of the gasifier through the feed port 11; then, air is fed into the gasifier through the gasifying agent inlet 1 or the loosening air inlet 16 at an appropriate flow rate to ignite in the reaction section 4. The flammable substance burns in the furnace, and the temperature of the gasification furnace gradually rises and is maintained for a certain period of time to achieve the purpose of preheating the gasifier;

[0040] Gasification of solid fuel: After the preheating of the furnace is completed, the flammable substance is switched to the gasification raw materials and enters the gasifier through the feed port 11. At the same time, the gasifying agent inlet 1 is switched to the gasifying agent, and the flow rate of the air entering through the loosening air inlet 16 is adjusted to make it reach an appropriate matching relationship with the feeding speed, ensuring that the gasification raw material particles are in the moving bed mode in the reaction zone 4. The gasification raw materials in the combustion area gradually move downward layer by layer. Under certain temperature and pressure conditions, the gasification raw materials undergo gasification reactions under the action of the gasifying agent to generate syngas containing combustible gases such as CO, H2, and CH4;

[0041] Step 3: Ash discharge process: The mixture of ash particles and inert bed material gradually falls along the discharge pipe 12 and accumulates in the discharge pipe to form a bed layer with a certain height. This can not only fully heat the preheating section 3, but also the residual carbon in the ash slag can be further burned or gasified to reduce the carbon content in the ash slag and further improve the gasification efficiency. When the height of the ash slag accumulation in the discharge pipe can be adjusted by changing the air flow rate entering through the discharge air inlet 17, the ash slag meeting the discharge conditions is discharged from the discharge port 18;

[0042] Step 5: Shutdown of the gasifier; During normal shutdown, first stop the input of the gasification raw materials, keep the gasifying agent flow rate and the air flow rate at the loosening air inlet unchanged. After the gasification raw materials are completely converted, close the delivery of the gasifying agent and the loosening air, discharge the remaining furnace materials and ash slag completely, and finally purge the system with air once.

[0043] Furthermore, after the preheating of the furnace is completed, the gasification raw materials enter the gasifier through the feed port 11, and the flow rate of the gasifying agent inlet 1 is increased to make the gasification raw material particles turn into a boiling fluidized state in the reaction zone 4. The gasification raw material particles are in full contact with the gasifying agent. Similarly, the solid fuel particles undergo gasification reactions in the reaction zone 4 to generate syngas containing combustible gases such as CO, H2, and CH4. The larger particle ash slag and the inert bed material are discharged together through the discharge pipe.

[0044] Further, after the preheating of the furnace chamber in step two is completed, the gasification raw materials enter the gasifier through the feed inlet 11. The gasifying agent at the gasifying agent inlet 1 is controlled to maintain a low flow rate, and the flow rate and pressure of the loosening air facing the discharge pipe 12 are increased, so that the materials in the discharge pipe 12 become a gushing state, corresponding to the spouted bed mode. The solid particles tumble more violently in the furnace chamber. Similarly, the solid fuel particles undergo a gasification reaction in the reaction zone 4 of the gasifier to generate syngas containing combustible gases such as CO, H2, and CH4. The ash residues with larger particles and the inert bed materials are discharged together through the discharge pipe 12. Since the flow rates of the gasifying agent and air are relatively large, the calorific value of the generated syngas is relatively low.

[0045] Further, the gasifier is designed as a composite gasifier that can switch among three operating modes: moving bed, fluidized bed, and spouted bed, and can be switched during operation according to the change of fuel.

[0046] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. According to the content of this specification, many modifications and changes can be made. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can understand and utilize the present invention well.

Claims

1. A composite gasification device based on a filtration combustion mode, characterized in that: It includes a gasifying agent inlet (1), a preheating section (3), a reaction section, a reforming section (5), a syngas outlet (10) and a discharging section. The gasifying agent inlet (1) is communicated with the preheating section (3). The upper and lower ends of the reaction section are respectively communicated with the preheating section (3) and the reforming section (5). The syngas outlet (10) is communicated with the reforming section (5). The discharging section is communicated with the reaction section. Both the preheating section (3) and the reforming section (5) include various forms of inert porous media fillers. The reaction section includes a feed inlet (11), a reaction zone (4) and a discharging pipe (12). The feed inlet (11) is communicated with the reaction zone (4). One end of the discharging pipe (12) is communicated with the lower end of the reaction zone (4). The other end of the feed pipe (12) is communicated with the discharging section. The two ends of the reaction zone (4) are respectively communicated with the preheating section (3) and the reforming section (5). The discharging section includes a discharging valve (6) and a discharging outlet (18). The discharging outlet (18) is communicated with the discharging pipe (12). A discharging valve (6) is provided on the discharging pipe (12). The discharging pipe (12) is arranged in the preheating section (3).

2. The composite gasification device based on a filtration combustion mode according to claim 1, wherein: An isobaric air chamber (2) is provided between the gasifying agent inlet (1) and the preheating section (3). The isobaric air chamber (2) adopts a single-side air inlet mode.

3. The composite gasification device based on a filtration combustion mode according to claim 1, wherein: The reaction zone (4) is a conical section with an inclination angle. The lower boundary of the reaction zone (4) is a conical air distribution plate (8). The upper boundary of the reaction zone (4) is a conical porous plate (9). The conical air distribution plate (8) and the conical porous plate (9) are arranged in parallel.

4. The composite gasification device based on a filtration combustion mode according to claim 1, wherein: The discharging pipe (12) is made of ceramic or heat-resistant material.

5. A composite gasification device based on a filtered combustion mode according to claim 1, characterized in that: A discharging air chamber (15) is communicated with the discharging pipe (12). A discharging air inlet (17) is communicated with the discharging air chamber (15).

6. The composite gasification device based on a filtration combustion mode according to claim 5, characterized in that: A loosening air chamber (14) is communicated with the discharging pipe (12). The loosening air chamber (14) is connected with the discharging air chamber (15). A loosening air inlet (16) is communicated with the loosening air chamber (14). A second porous flow equalizing plate (13) is provided at the connection between the loosening air chamber (14) and the discharging pipe (12).

7. A composite gasification device based on a filtration combustion mode according to claim 1, characterized in that: A first porous flow equalizing plate (7) is provided between the isobaric air chamber (2) and the preheating section (3).

8. The gasification method of a composite gasification device based on a filtration combustion mode according to any one of claims 1-7, characterized in that: It includes the following steps: Step 1: Prepare the gasification raw materials. Crush the solid fuel into particles. After drying treatment to make the moisture content meet the requirements, mix it evenly with the inert bed material as the gasification raw materials; Step 2: First, use the flammable substance gasifier to ignite, and preheat the gasifier to an appropriate temperature. Then, replace the flammable substance with gasification raw materials, and adjust the switching of the three operating modes of the gasifier by adjusting the matching relationship between the flow rate of the gasifying agent and the feeding speed. When the flow rate of the inlet gasifying agent flowing through the preheating section (3) is small, it corresponds to the moving bed mode, and the gasification raw materials in the combustion area slowly move downward layer by layer and react layer by layer. Increasing the flow rate of the inlet gasifying agent flowing through the preheating section (3) causes the gasification raw material particles to fluidize and transform into the fluidized bed mode. Or, the flow rate of the inlet gasifying agent flowing through the preheating section (3) remains at a small value, but the flow rate of the loosening air flowing through the central discharge pipe (12) is increased to change the operating state to the spouted bed mode. Then, under a specific operating mode, the fixed fuel particles react with the gasifying agent in the reaction zone (4) to complete the gasification process; Step 3: During the combustion and gasification processes of the fixed fuel, the ash generated is mixed and heat-transferred with the fuel and the inert bed material. In the moving bed operating state, the inert bed material will be discharged from the discharge pipe (12). In the fluidized bed and spouted bed operating states, the small particles further participate in the gasification process in the reaction zone (4), and the large particles are discharged from the discharge pipe (12) with the inert bed material. By controlling the gas velocity of the gasifying agent in the discharge pipe (12), the size and flow rate of the falling ash particles are controlled, and a certain bed material height is maintained in the discharge pipe (12). Those that meet the discharge conditions will be discharged from the discharge port (18) under the action of the discharge air; Step 4: When the gasifier stops operating, first stop the input of the gasification raw materials, keep the flow rate of the gasifying agent and the air flow rate at the loosening air inlet (16) unchanged. After the gas raw materials are completely converted, close the delivery of the gasifying agent and the loosening air, discharge the remaining furnace materials and ash residues, and finally purge it once with air.

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