Biomass pyrolysis gasification process

Abstract

The invention discloses a biomass pyrolysis gasification process. The process comprises the following steps: carrying out pyrolysis gasification reaction on a biomass raw material in a pyrolysis gasification furnace to generate biomass fuel gas and biochar; the biomass gas is subjected to secondary combustion in the secondary combustion chamber, and secondary combustion flue gas is obtained; a part of water in the process water tank is discharged into the heat exchanger; low-temperature flue gas generated in the waste heat boiler enters the heat exchanger; the water and the low-temperature flue gas are subjected to heat exchange in the heat exchanger; enabling the secondary combustion flue gas to enter a waste heat boiler; a denitration solution in the denitration solution storage tank is sprayed into the waste heat boiler through a spray gun arranged in the waste heat boiler and makes contact with secondary combustion flue gas in the waste heat boiler; the secondary combustion flue gas and the water subjected to heat exchange are subjected to dividing wall heat exchange in the waste heat boiler, and low-temperature flue gas and water vapor are formed; and at least part of the water vapor is conveyed to the heat accumulator to be stored. According to the process, heat energy can be fully utilized, and the influence of nitrogen-containing substances in the flue gas on equipment can be reduced.

Description

Technical Field

[0001] The invention relates to a biomass pyrolysis and gasification process. Background Art

[0002] Biomass energy has the remarkable characteristics of abundant resources, easy access, convertibility into clean energy, high heat, and universality. It plays an important role in meeting the future social energy demand and promoting social sustainable development. Biomass includes wood, straw, rice straw, wheat straw, bean straw, cotton stalk, husk, etc. Pyrolysis and gasification refers to the process of breaking organic macromolecules in biomass under anaerobic or anoxic conditions to produce small molecular gases, tar and residues. Pyrolysis and gasification technology has achieved harmless, reduced and resource utilization of biomass, and has great development prospects. Pyrolysis and gasification of straw raw materials obtains straw charcoal and then makes high value-added carbon-based compound fertilizer. At the same time, the heat generated by pyrolysis and gasification can also be converted into electricity, steam and other energy for human use. The collection and transportation of straw in my country is relatively extensive, resulting in the characteristics of high alkalinity, high moisture and low calorific value of the available biomass. The heat generated by pyrolysis in pyrolysis gasifiers is too low and has large fluctuations, which cannot be used too much, greatly limiting the raw materials and scope of use of biomass pyrolysis and gasification technology.

[0003] CN112919760A discloses a method for the coordinated treatment of domestic garbage, municipal sludge and kitchen waste, wherein the domestic garbage is crushed and sent to a pyrolysis gasification furnace, and pyrolysis, gasification and combustion are performed to produce synthesis gas and ash, which is used or landfilled as solid waste, and the synthesis gas is passed into a secondary combustion chamber and burned at a temperature above 850°C, and the flue gas generated by the combustion of the synthesis gas is passed into a flue gas purification system, and the flue gas is discharged after being treated by the flue gas purification system and meets the standards. A flue gas waste heat utilization system is arranged between the secondary combustion chamber and the flue gas purification system, and the combustion-supporting air is heated by an air heat exchanger in the flue gas waste heat utilization system, and the heated combustion-supporting air is respectively introduced into the pyrolysis gasification furnace and the secondary combustion chamber for combustion-supporting; a heat storage body is arranged in the secondary combustion chamber, and the heat storage body absorbs the heat generated by the combustion of the synthesis gas to maintain a high temperature state of more than 850°C in the secondary combustion chamber; an auxiliary burner is arranged in the secondary combustion chamber, and the auxiliary burner assists the high temperature state of more than 850°C in the secondary combustion chamber by burning an external fuel. This treatment method sets up a flue gas purification system after the flue gas waste heat utilization system and uses a semi-dry deacidification tower to deacidify the flue gas, but the treatment effect is poor.

[0004] CN206716713U discloses a system for processing urban organic solid waste resources into energy, including: a storage unit: a plurality of organic solid waste storage units are provided on the storage unit, and corresponding feed ports and discharge ports are provided on the organic solid waste storage unit. A pretreatment unit: the pretreatment unit includes an organic solid waste pretreatment unit corresponding to the organic solid waste storage unit, and the organic solid waste pretreatment unit includes a recyclable material collection device, a slurry collection device and an organic solid material collection device. The anaerobic fermentation unit includes an anaerobic fermentation tank, a biogas purification unit, a biogas storage cabinet, and a mechanical dehydration device. The pyrolysis gasification unit includes a feeding device, a pyrolysis gasification furnace, a secondary combustion chamber, a waste heat boiler, a steam turbine power generation unit, a flue gas purification unit, and a fly ash solidification unit connected in sequence. The system sets a flue gas purification unit after the waste heat boiler, and the nitrogen-containing substances in the flue gas are easy to corrode the waste heat boiler, and the heat energy cannot be fully utilized. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a biomass pyrolysis and gasification process, which can make full use of heat energy and reduce the impact of nitrogen-containing substances in flue gas on equipment. Furthermore, the heat energy generated by the process is high and has low volatility, which is conducive to client use.

[0006] The above purpose is achieved through the following technical solutions.

[0007] In one aspect, the present invention provides a biomass pyrolysis and gasification process, comprising the following steps:

[0008] (1) subjecting a biomass raw material to a pyrolysis and gasification reaction in a pyrolysis and gasification furnace to generate biomass fuel gas and biochar; wherein the moisture content of the biomass raw material is ≤40wt%, and the temperature of the pyrolysis layer in the pyrolysis and gasification furnace is 350-750°C;

[0009] (2) The biomass fuel gas is discharged through the combustible gas outlet provided in the pyrolysis gasification furnace and enters the secondary combustion chamber for secondary combustion to obtain secondary combustion flue gas; the temperature of the secondary combustion flue gas is 850-1200°C;

[0010] (3) A portion of the water in the process water tank is discharged from the first water outlet and then enters the heat exchanger from the cold source inlet of the heat exchanger; the low-temperature flue gas generated in the waste heat boiler enters the heat exchanger from the heat source inlet of the heat exchanger; the water and the low-temperature flue gas are heat exchanged in the heat exchanger to form heat-exchanged water and heat-exchanged flue gas; another portion of the water in the process water tank is discharged from the second water outlet and enters the heat accumulator;

[0011] (4) allowing the secondary combustion flue gas to enter the waste heat boiler; the denitrification solution in the denitrification solution storage tank is sprayed into the waste heat boiler through a spray gun provided in the waste heat boiler, and contacts with the secondary combustion flue gas in the waste heat boiler to reduce the concentration of nitrogen oxides in the secondary combustion flue gas; the secondary combustion flue gas and the water after heat exchange are subjected to inter-wall heat exchange in the waste heat boiler to form low-temperature flue gas and water vapor; and at least part of the water vapor is transported to the heat accumulator for storage.

[0012] According to the biomass pyrolysis and gasification process of the present invention, preferably, the diameter of the smallest surrounding sphere of the biomass raw material is less than or equal to 10 cm.

[0013] The biomass pyrolysis and gasification process according to the present invention preferably further comprises the following steps:

[0014] The flue gas after heat exchange enters the dust collector for dust removal to obtain clean flue gas; the clean flue gas is discharged from the chimney.

[0015] The biomass pyrolysis and gasification process according to the present invention preferably further comprises the following steps:

[0016] The biomass raw material is transported to a screw conveyor via a bucket elevator, and then transported to a discharge port of a pyrolysis gasifier via the screw conveyor; the biomass raw material enters the pyrolysis gasifier via the discharge port of the pyrolysis gasifier.

[0017] According to the biomass pyrolysis and gasification process of the present invention, preferably, step (1) further comprises the following steps:

[0018] The primary fan delivers air into the pyrolysis gasifier through the first vent at the bottom of the pyrolysis gasifier; the secondary fan delivers air into the pyrolysis gasifier through the second vent provided on the lower side wall of the pyrolysis gasifier;

[0019] The biochar is discharged from the pyrolysis gasification furnace through the rotating grate and spiral slag discharger arranged at the bottom of the pyrolysis gasification furnace and collected for later use.

[0020] According to the biomass pyrolysis and gasification process of the present invention, preferably, in step (2), the biomass fuel gas is allowed to enter the secondary combustion chamber from the secondary combustion chamber gasification gas burner; and the fuel gas booster fan is allowed to blow gas into the secondary combustion chamber.

[0021] According to the biomass pyrolysis and gasification process of the present invention, preferably, the secondary combustion flue gas is allowed to enter the waste heat boiler through the first connecting pipeline, and the gas induced draft fan is allowed to blow gas into the first connecting pipeline to promote the secondary combustion flue gas to enter the waste heat boiler;

[0022] The clean flue gas is discharged from the dust collector and transported to the chimney through the second connecting pipeline; the flue gas induced draft fan blows gas into the second connecting pipeline to promote the clean flue gas to enter the chimney.

[0023] According to the biomass pyrolysis and gasification process of the present invention, preferably, a part of the water vapor is directly transported from the waste heat boiler to the user end for use; and another part of the water vapor is transported to the user end for use via the heat accumulator.

[0024] According to the biomass pyrolysis and gasification process of the present invention, preferably, the pyrolysis and gasification furnace is an updraft pyrolysis and gasification furnace, and the dust collector is a bag dust collector.

[0025] According to the biomass pyrolysis and gasification process of the present invention, preferably, an air distribution plate is provided in the pyrolysis and gasification furnace, and a flow isolation baffle is provided in the secondary combustion chamber.

[0026] The process of the present invention can make biomass fully burn, produce secondary combustion flue gas with higher energy, and make full use of the heat energy contained in the secondary combustion flue gas. The present invention reduces the concentration of nitrogen oxides in the secondary combustion flue gas by spraying a denitrification solution into the waste heat boiler, reduces the corrosion of nitrogen oxides to the secondary boiler and subsequent equipment, and does not cause heat waste and loss. The present invention is provided with a heat accumulator, which can store part of the water vapor and reduce the fluctuation of heat energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a schematic diagram of the structure of a device used in the biomass pyrolysis and gasification process.

[0028] The reference numerals are as follows:

[0029] 1-bucket elevator; 2-screw feeder; 3-gasifier; 301-feeding port; 302-primary fan; 303-secondary fan; 304-first vent; 305-combustible gas outlet; 306-rotating grate; 8-secondary combustion chamber; 801-gasification gas burner in the secondary combustion chamber; 802-gas booster fan; 803-gas induced draft fan; 10-first connecting pipeline; 12-waste heat boiler; 14-heat accumulator; 17-user end; 18-desnitration solution storage tank; 21-heat exchanger; 23-dust collector; 24-flue gas induced draft fan; 25-second connecting pipeline; 26-chimney; 27-process water tank. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0031] The biomass pyrolysis and gasification process of the present invention comprises the following steps: (1) a pyrolysis and gasification step; (2) a secondary combustion step; (3) a water replenishment step; and (4) a waste heat boiler heat exchange step. In some embodiments, a flue gas purification step is also included. The serial number only serves to mark and distinguish the steps, and does not represent their order. For example, step (3) and step (4) can be performed simultaneously, or step (3) can be performed first and then step (4), or step (4) can be performed first and then step (3).

[0032] <Steps of Pyrolysis and Gasification>

[0033] The present invention causes a biomass raw material to undergo a pyrolysis and gasification reaction in a pyrolysis and gasification furnace to generate biomass fuel gas and biochar.

[0034] The biomass raw material can be selected from one or more of straw, rice straw, wheat straw, bean straw, cotton straw, rice husk, and wood. Preferably, the biomass raw material is straw. In this way, it can be fully pyrolyzed and gasified in the pyrolysis gasification furnace, thereby improving the utilization efficiency of energy.

[0035] The moisture content of biomass raw materials does not exceed 40%. The diameter of the smallest surrounding ball of biomass raw materials is ≤10cm. This is conducive to pyrolysis and gasification and improves calorific value.

[0036] The temperature of the pyrolysis layer in the pyrolysis gasification furnace is 350-750° C. Preferably, the pyrolysis gasification furnace is an updraft pyrolysis gasification furnace, which helps to fully pyrolyze and gasify the biomass raw materials.

[0037] In some embodiments, the biomass raw material is transported to a screw conveyor via an elevator, and then transported to a feed port of the pyrolysis gasifier via the screw conveyor, and enters the pyrolysis gasifier through the feed port. The feed port can be set at the top of the pyrolysis gasifier.

[0038] The fan can be used to deliver air into the pyrolysis furnace to promote the pyrolysis and gasification of the biomass raw materials. Specifically, the primary fan is used to deliver air into the pyrolysis and gasification furnace through the first vent provided at the bottom of the pyrolysis and gasification furnace. The secondary fan is used to deliver air into the pyrolysis and gasification furnace through the second vent provided at the lower part of the side wall of the pyrolysis and gasification furnace. Preferably, the air is delivered to the oxidation zone of the pyrolysis and gasification furnace. This helps to evenly mix with the biomass raw materials.

[0039] Preferably, an air distribution plate is provided in the pyrolysis gasification furnace, which helps to evenly distribute oxygen and promote the pyrolysis and gasification of biomass raw materials.

[0040] The biochar is discharged from the pyrolysis gasification furnace through the rotating grate and the spiral slag discharger arranged at the bottom of the pyrolysis gasification furnace and collected for later use.

[0041] <Secondary Combustion Steps>

[0042] The present invention discharges the biomass gas through the combustible gas outlet provided in the pyrolysis gasification furnace, enters the secondary combustion chamber for secondary combustion, and obtains secondary combustion flue gas. The biomass gas can be discharged from the pyrolysis gasification furnace through the combustible gas outlet provided on the upper part of the side wall of the pyrolysis gasification furnace, and enters the secondary combustion chamber through the gasification gas burner of the secondary combustion chamber for secondary combustion, and obtains secondary combustion flue gas. The temperature of the secondary combustion flue gas is 850 to 1200°C. Preferably, a flow baffle is provided in the secondary combustion chamber. In this way, the residence time of the flue gas in the secondary combustion chamber can be increased, and the generation of harmful substances such as dioxins can be reduced.

[0043] The gas heating fan blows gas into the secondary combustion chamber. This helps the secondary combustion to proceed fully and promotes the secondary combustion flue gas to enter the waste heat boiler.

[0044] <Steps for replenishing water>

[0045] The present invention discharges part of the water in the process water tank from the first water outlet, and then enters the heat exchanger from the cold source inlet of the heat exchanger; the low-temperature flue gas generated in the waste heat boiler enters the heat exchanger from the hot source inlet of the heat exchanger; the water and the low-temperature flue gas perform heat exchange in the heat exchanger to form water and flue gas after heat exchange; the other part of the water in the process water tank is discharged from the second water outlet and enters the heat accumulator. The process water tank replenishes water for the heat accumulator and the waste heat boiler. In this way, the heat contained in the low-temperature flue gas can be further used, the temperature of the water entering the waste heat boiler can be increased, and water vapor can be formed for use by the user end.

[0046] <Heat exchange steps of waste heat boiler>

[0047] The present invention allows the secondary combustion flue gas to enter the waste heat boiler; the denitrification solution in the denitrification solution storage tank is sprayed into the waste heat boiler through a spray gun arranged in the waste heat boiler, and contacts with the secondary combustion flue gas in the waste heat boiler to reduce the concentration of nitrogen oxides in the secondary combustion flue gas; the secondary combustion flue gas and the water after heat exchange are heat exchanged in the waste heat boiler to form low-temperature flue gas and water vapor; at least part of the water vapor is transported to the heat accumulator for storage. Low-temperature flue gas refers to a temperature lower than that of the secondary combustion flue gas.

[0048] In some embodiments, the secondary combustion flue gas is allowed to enter the waste heat boiler through the first connecting pipeline. The gas induced draft fan is allowed to blow gas into the first connecting pipeline to promote the secondary combustion flue gas to enter the waste heat boiler. The secondary combustion flue gas can enter the waste heat boiler through a flue gas inlet. The flue gas inlet can be arranged on the upper part of the side wall of the waste heat boiler.

[0049] The spray gun can be set on the top of the waste heat boiler. The spray gun can be set near the flue gas inlet. The present invention adopts a wet denitrification process. Compared with the dry method or semi-dry method, the wet denitrification has a higher denitrification efficiency. The water introduced by the wet denitrification can be used as a raw material for water vapor, and will not cause a large amount of denitrification wastewater. Carrying out wet denitrification in the waste heat boiler will not reduce the calorific value of the secondary combustion flue gas, so that the heat energy is fully utilized. The spray gun of the present invention is set near the flue gas inlet, and the secondary combustion flue gas can contact with the denitrification solution after entering the secondary boiler, thereby reducing the corrosion of nitrogen oxides to the secondary boiler.

[0050] The water after heat exchange can be discharged from the heat exchanger through the cold source outlet of the heat exchanger, and then enter the waste heat boiler through the water inlet of the waste heat boiler. The water inlet can be set at the top of the waste heat boiler. The water inlet can be set close to the side wall of the secondary boiler, which side wall is opposite to the side wall where the flue gas inlet is set.

[0051] Part of the water vapor is transported from the first water vapor outlet of the waste heat boiler to the heat accumulator for storage. The water vapor can be directly transported to the user end for use from the second water vapor outlet of the waste heat boiler; or it can be stored in the heat accumulator and then transported to the user end for use from the heat accumulator. This can reduce the fluctuation of thermal energy and facilitate the use of the user end.

[0052] <Steps for flue gas purification>

[0053] The present invention allows the flue gas after heat exchange to enter the dust collector for dust removal to obtain clean flue gas, and the clean flue gas is discharged from the chimney. The dust collector can be a bag dust collector.

[0054] The flue gas after heat exchange can be discharged from the heat exchanger through the heat source outlet of the heat exchanger and enter the dust collector.

[0055] In certain embodiments, the clean flue gas is discharged from the dust collector and transported to the chimney through the second connecting pipeline; the flue gas induced draft fan blows gas into the second connecting pipeline to promote the clean flue gas to enter the chimney.

[0056] Example 1

[0057] refer to Figure 1 The biomass pyrolysis and gasification process of this embodiment includes the following steps:

[0058] (1) The straw is transported to the screw feeder 2 via the bucket elevator 1, and then transported to the discharge port 301 of the pyrolysis gasification furnace 3 via the screw feeder 2, and enters the pyrolysis gasification furnace 3 via the discharge port 301. In this embodiment, the pyrolysis gasification furnace 3 is an upward suction pyrolysis gasification furnace. The moisture content of the straw does not exceed 40%, and the diameter of the minimum surrounding ball of the straw is ≤10 cm. In this way, the straw can be fully pyrolyzed and gasified, and the calorific value of the flue gas can be increased.

[0059] The primary fan 302 delivers air into the pyrolysis gasification furnace 3 through the first vent 304 provided at the bottom of the pyrolysis gasification furnace 3. The secondary fan 303 delivers air to the oxidation zone of the pyrolysis gasification furnace 3 through the second vent (not shown) provided at the lower part of the side wall of the pyrolysis gasification furnace 3.

[0060] The straw is pyrolyzed and gasified in the pyrolysis gasification furnace 3 to generate biomass gas and biochar. The temperature of the pyrolysis layer in the pyrolysis gasification furnace 3 is 350-750° C. An air distribution plate (not shown) is provided in the pyrolysis gasification furnace 3 to promote uniform distribution of air in the pyrolysis gasification furnace 3.

[0061] The biochar is discharged from the pyrolysis gasification furnace 3 through the rotary grate 306 and the spiral slag discharger (not shown) provided at the bottom of the pyrolysis gasification furnace 3 and collected for later use.

[0062] (2) The biomass fuel gas is discharged through the combustible gas outlet 305 provided at the upper part of the side wall of the pyrolysis gasifier, and enters the secondary combustion chamber 8 through the secondary combustion chamber gasification gas burner 801 for secondary combustion to obtain secondary combustion flue gas. The temperature of the secondary combustion flue gas is 850-1200°C, and a flow baffle is provided in the secondary combustion chamber 8.

[0063] The gas heating blower 802 is caused to blow gas into the secondary combustion chamber 8 to supply air into the secondary combustion chamber 8 .

[0064] (3) A portion of the water in the process water tank 27 is discharged from the first water outlet (not shown), and then enters the heat exchanger 21 from the cold source inlet (not shown) of the heat exchanger 21. The low-temperature flue gas generated in the waste heat boiler 12 is discharged from the flue gas outlet provided at the top of the waste heat boiler 12 (not shown), and enters the heat exchanger 21 from the heat source inlet (not shown); water and low-temperature flue gas perform heat exchange in the heat exchanger 21 to form heat-exchanged water and heat-exchanged flue gas.

[0065] Another part of the water in the process water tank 27 is discharged from a second water outlet (not shown) and enters the heat accumulator 14 .

[0066] (4) The secondary combustion flue gas enters the waste heat boiler 12 through the first connecting pipeline 10 and the flue gas inlet (not shown) provided at the upper part of the side wall of the waste heat boiler 12. The gas induced draft fan 803 blows gas into the first connecting pipeline 10 to promote the secondary combustion flue gas to enter the waste heat boiler 12.

[0067] The denitration solution in the denitration solution storage tank 18 is sprayed into the waste heat boiler 12 through a spray gun (not shown) disposed in the waste heat boiler 12, and contacts with the secondary combustion flue gas in the waste heat boiler 12 to reduce the concentration of nitrogen oxides in the secondary combustion flue gas. The spray gun is disposed at the top of the waste heat boiler 12 and near the flue gas inlet.

[0068] The water after heat exchange is discharged from the heat exchanger through the cold source outlet (not shown) of the heat exchanger 21, and then enters the waste heat boiler 12 through the water inlet (not shown) of the waste heat boiler 12. The water inlet is arranged at the top of the waste heat boiler 12 and is arranged close to the side wall, which is opposite to the side wall where the flue gas inlet is arranged. The secondary combustion flue gas and the water after heat exchange are subjected to inter-wall heat exchange in the waste heat boiler 12 to form low-temperature flue gas and water vapor. Part of the water vapor is transported from the first water vapor outlet (not shown) of the waste heat boiler 12 to the heat accumulator 14 for storage. The water vapor can be directly transported from the second water vapor outlet (not shown) of the waste heat boiler 12 to the user end 17 for use; or it can be stored in the heat accumulator 14 and then transported from the heat accumulator 14 to the user end 17 for use.

[0069] (5) The flue gas after heat exchange is discharged from the heat exchanger 21 through the heat source outlet, and enters the dust collector 23. After dust removal by the dust collector 23, clean flue gas is obtained. The dust collector 23 is a bag dust collector. The clean flue gas is transported to the chimney 26 through the second connecting pipeline 25 and discharged from the chimney 26. The flue gas induced draft fan 24 blows gas into the second connecting pipeline 25 to promote the clean flue gas to enter the chimney 26.

[0070] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be conceived by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A biomass pyrolysis and gasification process, characterized in that: The steps include: (1) subjecting a biomass raw material to a pyrolysis and gasification reaction in a pyrolysis and gasification furnace to generate biomass fuel gas and biochar; wherein the moisture content of the biomass raw material is ≤40wt%, and the temperature of the pyrolysis layer in the pyrolysis and gasification furnace is 350-750°C; (2) The biomass fuel gas is discharged through the combustible gas outlet provided in the pyrolysis gasification furnace and enters the secondary combustion chamber for secondary combustion to obtain secondary combustion flue gas; the temperature of the secondary combustion flue gas is 850-1200°C; (3) A portion of the water in the process water tank is discharged from the first water outlet and then enters the heat exchanger from the cold source inlet of the heat exchanger; the low-temperature flue gas generated in the waste heat boiler enters the heat exchanger from the heat source inlet of the heat exchanger; the water and the low-temperature flue gas are heat exchanged in the heat exchanger to form heat-exchanged water and heat-exchanged flue gas; another portion of the water in the process water tank is discharged from the second water outlet and enters the heat accumulator; (4) allowing the secondary combustion flue gas to enter the waste heat boiler; the denitrification solution in the denitrification solution storage tank is sprayed into the waste heat boiler through a spray gun provided in the waste heat boiler, and contacts with the secondary combustion flue gas in the waste heat boiler to reduce the concentration of nitrogen oxides in the secondary combustion flue gas; the secondary combustion flue gas and the water after heat exchange are subjected to inter-wall heat exchange in the waste heat boiler to form low-temperature flue gas and water vapor; and at least part of the water vapor is transported to the heat accumulator for storage.

2. The biomass pyrolysis and gasification process according to claim 1, characterized in that: The diameter of the smallest enclosing sphere of the biomass raw material is less than or equal to 10 cm.

3. The biomass pyrolysis and gasification process according to claim 1, characterized in that: The following steps are also included: The flue gas after heat exchange enters the dust collector for dust removal to obtain clean flue gas; the clean flue gas is discharged from the chimney.

4. The biomass pyrolysis and gasification process according to claim 1, characterized in that: The following steps are also included: The biomass raw material is transported to a screw conveyor via a bucket elevator, and then transported to a discharge port of a pyrolysis gasifier via the screw conveyor; the biomass raw material enters the pyrolysis gasifier via the discharge port of the pyrolysis gasifier.

5. The biomass pyrolysis and gasification process according to claim 1, characterized in that: Step (1) also includes the following steps: The primary fan delivers air into the pyrolysis gasifier through the first vent at the bottom of the pyrolysis gasifier; the secondary fan delivers air into the pyrolysis gasifier through the second vent provided on the lower side wall of the pyrolysis gasifier; The biochar is discharged from the pyrolysis gasification furnace through the rotating grate and spiral slag discharger arranged at the bottom of the pyrolysis gasification furnace and collected for later use.

6. The biomass pyrolysis and gasification process according to claim 1, characterized in that: In step (2), the biomass fuel gas is allowed to enter the secondary combustion chamber from the secondary combustion chamber gasification gas burner; and the fuel gas pressure fan is allowed to blow gas into the secondary combustion chamber.

7. The biomass pyrolysis and gasification process according to claim 3, characterized in that: The secondary combustion flue gas is allowed to enter the waste heat boiler through the first connecting pipeline, and the gas induced draft fan is allowed to blow gas into the first connecting pipeline to promote the secondary combustion flue gas to enter the waste heat boiler; The clean flue gas is discharged from the dust collector and transported to the chimney through the second connecting pipeline; the flue gas induced draft fan blows gas into the second connecting pipeline to promote the clean flue gas to enter the chimney.

8. The biomass pyrolysis and gasification process according to claim 1, characterized in that: Part of the water vapor is directly transported by the waste heat boiler to the user end for use; the other part of the water vapor is transported to the user end for use via the heat accumulator.

9. The biomass pyrolysis and gasification process according to claim 1, characterized in that: The pyrolysis gasification furnace is an upward suction pyrolysis gasification furnace, and the dust collector is a bag dust collector.

10. The biomass pyrolysis and gasification process according to any one of claims 1 to 9, characterized in that: An air distribution plate is arranged in the pyrolysis gasification furnace, and a flow isolation baffle is arranged in the secondary combustion chamber.

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