A fixed bed continuous gasification reaction method

Abstract

A fixed bed continuous gasification reaction method. The traditional gasification furnace only has a single heating cavity, and the temperature rising, pyrolysis and gasification are simultaneously completed in the same area, the heating rate of the raw material is uncontrollable, the internal gasification of the large raw material is insufficient, the carbon conversion rate is low, the residual carbon content of the residue is high, and the raw material is seriously wasted. The ash is directly discharged nakedly, the ash and gasification gas are directly discharged, the fuel gas is wasted, there is no independent ash box buffer structure, the ash and residual gasification gas cannot be separated, and the tail gas is directly discharged to pollute the environment. The application comprises a spiral feeding device, a spiral discharging device and a gasification reaction tube, the feeding end of the gasification reaction tube is fixed at the discharging port of the spiral feeding device, the discharging end is fixed at the feeding end of the spiral discharging device, and the outer part of the gasification reaction tube is fixed with a heater. The application is used for fixed bed continuous gasification reaction.

Description

Technical Field

[0001] This invention relates to a fixed-bed continuous gasification reaction method. Background Technology

[0002] Currently, biomass and coal fixed-bed gasification equipment is mainly divided into two types: intermittent fixed-bed gasifiers and single-tube continuous gasifiers. Intermittent fixed-bed gasifiers: gasification is carried out in a closed system after a single charge. After the reaction is completed, the machine is stopped to remove ash. Continuous feeding and ash removal are not possible. Each batch of production requires opening the furnace door to add material and clean ash. A large amount of high-temperature gas leaks out of the furnace, resulting in high energy consumption, serious dust pollution, and high manual operation intensity. Single-tube continuous gasification unit: It has only a single reaction straight tube, small raw material processing capacity, short heating section, and insufficient raw material gasification reaction; it is equipped with a simple straight cylinder feed and discharge screw, without segmented temperature control heating structure, resulting in low gasification efficiency and high carbon dust impurities in the gas.

[0003] Intermittent gasifiers must be started and stopped in batches. The feeding and ash removal stages disrupt the sealed gasification atmosphere inside the furnace, making it easy for air to seep in, resulting in high fuel combustion losses and potential explosion hazards. Single-tube gasification equipment has low capacity and cannot be adapted to large-scale continuous production.

[0004] Traditional gasifiers have only a single heating chamber, where heating, pyrolysis, and gasification are all completed simultaneously in the same area. The heating rate of the raw materials is uncontrollable, large pieces of raw materials are not fully gasified, resulting in low carbon conversion rate, high carbon content in the residue, and serious waste of raw materials.

[0005] The ash is discharged directly in the open, and the ash residue carries gasified gas directly into the air, resulting in high gas consumption. There is no independent ash box buffer structure, so the ash residue and residual gasified gas cannot be separated, and the exhaust gas is directly discharged, polluting the environment.

[0006] The gasifying agent is only introduced into the bottom of the reaction tube at a single point, resulting in uneven upward distribution of the gas flow. This leads to localized overheating of the material inside the tube, localized stagnation of the reaction, unstable gas composition, and high difficulty in subsequent purification and utilization. Summary of the Invention

[0007] The purpose of this invention is to solve the above-mentioned technical problems and provide a fixed-bed continuous gasification reaction method.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A fixed-bed continuous gasification reaction method, the method comprising the following steps: (1) The three-stage tubular electric heating furnace is heated to the set process temperature in stages, and the gasification medium is continuously introduced from the gasification agent inlet to replace the air in the gasification reaction tube and establish an inert gasification atmosphere. (2) Biomass pellets / raw coal pellets are fed into the feed hopper. The feed drive motor drives the screw feeder to transport the material. By controlling the motor frequency, the material level in the gasification reaction tube can be controlled in coordination with the discharge screw. The material is continuously fed into the top of the gasification reaction tube to prevent the gas from leaking upward. (3) The material moves slowly downward in the vertical gasification reaction tube by gravity. The material movement speed can be controlled by controlling the frequency of the discharge motor. The material passes through the drying section, pyrolysis section and high-temperature gasification section of the three-section tubular electric heating furnace in sequence. The material comes into countercurrent contact with the gasifying agent flowing upward at the bottom, and gradually completes the removal of moisture, pyrolysis of organic matter and gasification of carbon elements to generate combustible gas. (4) The gas generated by the reaction gathers upward and is uniformly discharged from the gas outlet to the purification and storage system; (5) The ash and slag after the gasification reaction fall into the bottom discharge hopper. The discharge drive motor drives the screw discharge device to transport the ash and slag. The screw pitch of the discharge screw gradually decreases. The screw squeezes the ash and slag to form a lower air-locking material seal to prevent outside air from flowing back into the reaction tube. The ash and slag are sent to the ash box for temporary storage. (6) A small amount of residual gasification gas carried in the ash slag gathers upward and is led out through the ash box outlet and integrated into the main gas pipeline for unified recycling, with no waste gas or dust being directly discharged.

[0009] In the fixed-bed continuous gasification reaction method, the feed end of the gasification reaction tube is fixed at the discharge port of the screw feeder, the discharge end is fixed at the feed end of the screw discharger, and a heater is fixedly surrounding the outside of the gasification reaction tube.

[0010] The fixed-bed continuous gasification reaction method includes a heater comprising two semi-circular heating cylinders connected by a hinge.

[0011] The fixed-bed continuous gasification reaction method is described above. The semi-circular heating cylinder has a dual-cavity structure, including an inner cylinder and an outer cylinder arranged concentrically. Multiple semi-ring inner clamping blocks are fixed sequentially along the length direction inside the inner cylinder. The cavity between the inner cylinder and the outer cylinder is divided into three independent chambers by two partitions. Each chamber is fixed with a heating wire.

[0012] The fixed-bed continuous gasification reaction method described above has a gasifying agent inlet at the bottom and a gasification gas outlet at the top of the gasification reaction tube.

[0013] The fixed-bed continuous gasification reaction method includes a screw conveyor as the screw discharge device, and an ash box is fixed at the tail of the screw conveyor. Beneficial effects

[0014] 1. The present invention features a double-helix sealed conveying structure, which enables continuous feeding and ash discharge 24 hours a day, maintaining the gasification reaction straight pipe in a sealed manner throughout the process, and preventing problems such as unorganized air infiltration and gas backflow leakage.

[0015] 2. The heater of this invention adopts a three-section tubular electric heating furnace with zoned temperature control, and the temperature is gradually increased along the direction of material falling, so as to complete the staged reaction of raw material drying, pyrolysis and gasification in sequence, improve carbon conversion rate, reduce residual carbon content of residue, and explore the influence of process parameters to achieve the purpose of conducting experiments.

[0016] 3. The present invention uses an independent ash box to buffer and collect ash residue, and a matching ash box outlet to recover residual gasified gas carried by the ash residue, thereby reducing the emission of exhaust dust.

[0017] 4. The gasification reaction tube of the present invention is provided with a special gasification agent inlet at the bottom, which uniformly supplies the gasification medium to the reaction straight tube, stabilizes the gasification reaction conditions inside the tube, and produces a gasified gas with uniform composition. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the gasification reaction tube. Figure 3 This is a schematic diagram of the heater structure; In the diagram: 1. Feed hopper; 2. Screw feeder; 3. Gasification reaction tube; 4. Heater; 5. Screw conveyor; 6. Ash box; 7. Gasification gas outlet; 8. Gasification agent inlet; 9. Discharge hopper; 10. Ash box outlet; 11. Feed drive motor; 12. Discharge drive motor; 41. Hinge; 42. Inner cylinder; 43. Heating wire; 44. Outer cylinder; 45. Partition plate; 46. Semi-ring inner clamping block; 47. Fixing plate. Detailed Implementation

[0019] See Figures 1-3 A fixed-bed continuous gasification reaction method, the method comprising the following steps: (1) The three-stage tubular electric heating furnace is heated to the set process temperature in stages, and the gasification medium is continuously introduced from the gasification agent inlet to replace the air in the gasification reaction tube and establish an inert gasification atmosphere. (2) Biomass pellets / raw coal pellets are fed into the feed hopper. The feed drive motor drives the screw feeder to transport the material. By controlling the motor frequency, the material level in the gasification reaction tube can be controlled in coordination with the discharge screw. The material is continuously fed into the top of the gasification reaction tube to prevent the gas from leaking upward. (3) The material moves slowly downward in the vertical gasification reaction tube by gravity. The material movement speed can be controlled by controlling the frequency of the discharge motor. The material passes through the drying section, pyrolysis section and high-temperature gasification section of the three-section tubular electric heating furnace in sequence. The material comes into countercurrent contact with the gasifying agent flowing upward at the bottom, and gradually completes the removal of moisture, pyrolysis of organic matter and gasification of carbon elements to generate combustible gas. (4) The gas generated by the reaction gathers upward and is uniformly discharged from the gas outlet to the purification and storage system; (5) The ash and slag after the gasification reaction fall into the bottom discharge hopper. The discharge drive motor drives the screw discharge device to transport the ash and slag. The screw pitch of the discharge screw gradually decreases. The screw squeezes the ash and slag to form a lower air-locking material seal to prevent outside air from flowing back into the reaction tube. The ash and slag are sent to the ash box for temporary storage. (6) A small amount of residual gasification gas carried in the ash slag gathers upward and is led out through the ash box outlet and integrated into the main gas pipeline for unified recycling, with no waste gas or dust being directly discharged.

[0020] A fixed-bed continuous gasification reaction method comprises a screw feeder 2, a screw discharger and a gasification reaction tube 3. The feed end of the gasification reaction tube is fixed at the discharge port of the screw feeder, and the discharge end is fixed at the feed end of the screw discharger. A heater 4 is fixedly surrounding the gasification reaction tube.

[0021] The feed hopper is a cylindrical structure with a diameter of 100mm and a height of 100mm. It is installed on the top of the screw feeder by sealing with an internal hex bolt flange. The flange thickness is uniformly 10mm and is used to buffer the solid raw materials to be gasified. The feed drive motor 11 is a variable frequency drive motor, which is connected to the left end of the horizontal cylinder of the screw feeder and can steplessly adjust the feed conveying speed. Screw feeder: horizontal sealed cylinder with an inner diameter of 60mm, equipped with variable pitch screw blades inside. During the conveying process, the material is compressed to form a dense material seal, preventing the high-temperature gas inside the gasification straight pipe from backflowing upwards; the bottom flange of the vertical feeding section of the screw feeder is sealed and connected to the top of the gasification reaction pipe. The gasification reaction tube is a vertically arranged cylindrical pipe with an outer diameter of 60 mm and a total height of 1220 mm, and is covered by a heater. The raw material falls into the pipe from the top and moves downward by gravity, coming into countercurrent contact with the gasifying agent introduced at the bottom. The drying, pyrolysis and gasification processes are completed in a segmented temperature-controlled environment. A gasification gas outlet with an outer diameter of 20 mm is opened on the upper part of the straight pipe side wall to collect the combustible gas generated by gasification.

[0022] The gasifying agent inlet is located on the side wall of the discharge hopper and is connected to an external gasifying agent supply pipeline. Water vapor, air, carbon dioxide and other gasification media are uniformly transported into the pipeline to fully contact and react with the falling solid materials.

[0023] The fixed-bed continuous gasification reaction method has a gasification agent inlet 8 at the bottom and a gasification gas outlet 7 at the top of the gasification reaction tube.

[0024] The fixed-bed continuous gasification reaction method includes a screw conveyor 5, and an ash box 6 is fixed at the tail of the screw conveyor.

[0025] The discharge hopper 9 is a cylindrical structure with a diameter of 60mm and a height of 100mm, and is flange-sealed to the bottom of the gasification reaction pipe; The discharge drive motor 12 is a variable frequency motor that drives the horizontally arranged spiral discharge device. The screw discharge device is a horizontal closed cylinder. The internal screw squeezes the ash and slag to form a lower airlock material seal to prevent outside air from entering the gasification reaction pipe from the ash discharge channel. The ash box is a cylindrical buffer box with a diameter of 150mm and a height of 200mm. It is sealed to the end of the screw discharge device via a flange to temporarily store the ash residue after gasification. The top of the box has an ash box gas outlet 10 (outer diameter 20mm) to collect the residual gasification gas trapped in the gaps between the ash residue and to recover it to the gas pipeline.

[0026] The fixed-bed continuous gasification reaction method described above includes a heater comprising two semi-circular heating cylinders connected by a hinge 41.

[0027] The fixed-bed continuous gasification reaction method is described above. The semi-circular heating cylinder has a dual-cavity structure, including an inner cylinder 42 and an outer cylinder 44 arranged concentrically. Multiple semi-ring inner clamping blocks 46 are fixed in sequence along the length direction inside the inner cylinder. The cavity between the inner cylinder and the outer cylinder is divided into three independent chambers by two partitions 45. A heating wire 43 is fixed in each chamber.

[0028] The heater has an overall height of 1200mm and a width of 700mm. The heater surrounds the outer wall of the gasification reaction tube. The heater is divided into three independent chambers along the material falling direction by a partition: a drying heating section, a pyrolysis heating section, and a high-temperature gasification section. The heating wires in each chamber have independently controlled heating temperatures, realizing a gradient heating reaction of the material. With the three-stage independent temperature control heating structure, the material completes drying, pyrolysis, and gasification in steps, increasing the carbon conversion rate to over 95%, reducing the residual carbon content of the ash residue from 20% to less than 5%, and significantly improving the raw material utilization rate.

[0029] Working principle: Equipment start-up and preheating: The three-section tubular electric heating furnace is heated to the set process temperature in stages. The gasification medium is continuously introduced from the gasification agent inlet to replace the air in the gasification reaction tube and establish an inert gasification atmosphere. Continuous closed feeding: Biomass pellets / raw coal pellets are fed into the feed hopper, and the feed drive motor drives the screw feeder to transport the material. By controlling the motor frequency, the material level in the gasification reaction tube can be controlled in coordination with the discharge screw. The material is continuously fed into the top of the gasification reaction tube, preventing the upward leakage of gas. The material moves slowly downwards in the vertical gasification reaction tube by gravity. The material movement speed can be controlled by controlling the frequency of the discharge motor. The material passes through the drying section, pyrolysis section and high-temperature gasification section of the three-section tubular electric heating furnace in sequence. The material comes into countercurrent contact with the gasifying agent flowing upwards from the bottom, and gradually completes the removal of moisture, pyrolysis of organic matter and gasification of carbon elements to generate combustible gas. The gas produced by the reaction gathers upwards and is uniformly discharged from the gas outlet to the purification and storage system. After the gasification reaction, the ash falls into the bottom discharge hopper. The discharge drive motor drives the screw discharge device to transport the ash. The pitch of the discharge screw gradually decreases, and the screw squeezes the ash to form a lower airlock seal to prevent outside air from flowing back into the reaction tube. The ash is then sent to the ash box for temporary storage. The small amount of residual gasification gas trapped in the ash slag gathers upward and is led out through the ash box outlet 10 and integrated into the main gas pipeline for unified recovery, with no waste gas or dust being directly discharged.

[0030] Example 1: Continuous gasification of biomass wood pellets Raw material: Wood chips with a moisture content of 12%; The three-section tubular electric heating furnace has the following section temperatures: drying section 220℃, pyrolysis section 450℃, and gasification section 780℃; the gasification agent is a mixture of water vapor and a small amount of air. The feed drive motor speed is 10 r / min, the discharge drive motor speed is 8 r / min, and the total residence time of the material in the gasification reaction tube is 55 min. Operational results: The equipment operated continuously and stably for 72 hours without gas leakage or air backflow; the residual carbon content of the ash residue was 4.2%, the gas collection rate was 96.3%, there was no dust or exhaust gas discharge, and the calorific value of the gasified gas fluctuated stably by ≤5%.

[0031] Example 2: Gasification of Small Pieces of Raw Coal Raw material: Anthracite particles with a diameter of 3-10mm; The heating temperature is as follows: drying section 180℃, pyrolysis section 520℃, and gasification section 900℃; only water vapor is introduced as the gasifying agent. Reduce the speed of the feed drive motor to 6 r / min and the speed of the discharge drive motor to 5 r / min, and extend the gasification residence time to 70 min. Operational results: Carbon conversion rate of 95.7%, residual gas recovery in the ash box accounts for 16% of the total gas production, and there is no blockage or gas leakage during continuous operation.

[0032] Example 3: Gasification of Straw Agglomerates Three-stage heating temperatures: drying stage 260℃, pyrolysis stage 430℃, gasification stage 750℃; increase the speed of the feed drive motor to 14r / min and shorten the residence time in the drying stage; Operational results: After the straw clumps are loosened by the upper screw extrusion, they enter the reaction tube smoothly without bridging or blockage, and the produced gas composition is uniform and stable.

Claims

1. A fixed-bed continuous gasification reaction method, characterized in that: The method includes the following steps: (1) The three-stage tubular electric heating furnace is heated to the set process temperature in stages, and the gasification medium is continuously introduced from the gasification agent inlet to replace the air in the gasification reaction tube and establish an inert gasification atmosphere. (2) Biomass pellets / raw coal pellets are fed into the feed hopper. The feed drive motor drives the screw feeder to transport the material. By controlling the motor frequency, the material level in the gasification reaction tube can be controlled in coordination with the discharge screw. The material is continuously fed into the top of the gasification reaction tube to prevent the gas from leaking upward. (3) The material moves slowly downward in the vertical gasification reaction tube by gravity. The material movement speed can be controlled by controlling the frequency of the discharge motor. The material passes through the drying section, pyrolysis section and high-temperature gasification section of the three-section tubular electric heating furnace in sequence. The material comes into countercurrent contact with the gasifying agent flowing upward at the bottom, and gradually completes the removal of moisture, pyrolysis of organic matter and gasification of carbon elements to generate combustible gas. (4) The gas generated by the reaction gathers upward and is uniformly discharged from the gas outlet to the purification and storage system; (5) The ash and slag after the gasification reaction fall into the bottom discharge hopper. The discharge drive motor drives the screw discharge device to transport the ash and slag. The screw pitch of the discharge screw gradually decreases. The screw squeezes the ash and slag to form a lower air-locking material seal to prevent outside air from flowing back into the reaction tube. The ash and slag are sent to the ash box for temporary storage. (6) A small amount of residual gasification gas carried in the ash slag gathers upward and is led out through the ash box outlet and integrated into the main gas pipeline for unified recycling, with no waste gas or dust being directly discharged.

2. The fixed-bed continuous gasification reaction method according to claim 1, characterized in that: The feed end of the gasification reaction tube is fixed at the discharge port of the screw feeder, and the discharge end is fixed at the feed end of the screw dischargeer. A heater is fixed around the outside of the gasification reaction tube.

3. The fixed-bed continuous gasification reaction method according to claim 2, characterized in that: The heater comprises two semi-circular heating cylinders connected by a hinge.

4. The fixed-bed continuous gasification reaction method according to claim 3, characterized in that: The semi-circular heating cylinder has a dual-cavity structure, including an inner cylinder and an outer cylinder arranged concentrically. Multiple semi-ring inner clamping blocks are fixed sequentially along the length of the inner cylinder. The cavity between the inner cylinder and the outer cylinder is divided into three independent chambers by two partitions, and a heating wire is fixed in each chamber.

5. A fixed-bed continuous gasification reaction method according to claim 4, characterized in that: The vaporization reaction tube has a vaporizing agent inlet at the bottom and a vaporizing gas outlet at the top.

6. The fixed-bed continuous gasification reaction method according to claim 5, characterized in that: The aforementioned screw discharge device includes a screw conveyor, and a ash box is fixed to the tail of the screw conveyor.

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