Process method and device for co-production of carbon through positive pressure biomass gasification

Abstract

The invention discloses a process method and device for co-production of carbon through positive pressure biomass gasification. The process method comprises the following steps: transporting the biomass fuel to a stokehole stock bin; biomass fuel is fed into the fluidized bed gasification furnace through the stokehole positive pressure feeding system, and bed materials are supplemented to the fluidized bed gasification furnace at any time through the bed material supply system according to needs; biomass fuel is gasified under the action of a centrifugal fan at the bottom of the fluidized bed gasification furnace, the supply quantity of fluidizing air and an air gasifying agent is adjusted through a variable-frequency centrifugal fan, the temperature of the fluidized bed gasification furnace is adjusted, and therefore the proportion of generated gasified fuel gas to biomass charcoal is adjusted; blocky biomass charcoal falls into the bottom end of the fluidized bed gasification furnace and is collected and utilized; and the ash-shaped biomass charcoal sinks through a cyclone separator at the upper end of the fluidized bed gasification furnace and enters an ash discharging system to be collected and utilized. The device is operated under positive pressure, and better adapts to the change of downstream fuel gas and biomass charcoal requirements and the change of upstream biomass fuel.

Description

Technical Field

[0001] The invention relates to the technical field of biomass gasification tar utilization, and in particular to a process method and device for positive pressure biomass gasification and co-production of charcoal. Background Art

[0002] There are currently two main types of biomass gasification technologies: fixed bed and fluidized bed gasifiers. Fixed bed gasifiers require the entire bed to maintain porosity, and have high requirements for raw materials. Generally, the biomass bulk material needs to be briquette-processed before entering the furnace. The raw materials stay in the furnace for a long time and need to have a certain thermal stability. When biomass is used as a fixed bed gasification raw material, it is easy to stick and deform after reaching the gasification temperature, resulting in poor air permeability of the bed and disordered gas distribution. In severe cases, it will cause the gasifier to stop. At present, biomass fixed bed gasification is only suitable for small-scale installed capacity. Compared with fixed bed gasifiers, fluidized bed gasifiers are more adaptable to biomass fuels and are easier to achieve large-scale continuous operation.

[0003] The products of gasification are mainly divided into biomass gas and biochar. Under the condition of air gasification agent, the gas obtained from biomass gasification can be used as a substitute fuel for coal, and is used in coal-fired power plants, lime kilns, glass kilns, etc. Biochar has the value of improving farmland. Its high carbon content and porous structure enable biochar to significantly improve soil structure and fertility, fix carbon in the atmosphere to mitigate climate change, and adsorb and degrade harmful substances in the environment. Therefore, it has important application value in agriculture, environmental remediation and climate change. By strictly controlling the pyrolysis conditions, biochar with engineering properties and high reliability can be created. This carbon will be suitable for more complex applications, such as graphite and activated carbon electrode materials in lithium-ion batteries and supercapacitors.

[0004] When biomass gas is delivered to power plants or industrial kilns, the industrial furnaces often have reduced production loads due to staggered production stops, and the demand for gas is reduced. In addition, the market demand for biomass gas and biochar is sensitive to seasons and locations, and the types of biomass fuels in different places are also different. Wood is more suitable for producing biochar than straw, and straw is more suitable for gasification. However, the gasifier in the prior art does not have good adaptability and product adjustment capabilities (i.e., adjusting the output ratio of biomass gas and biochar) during the gasification process, and thus cannot take into account the adaptability of upstream raw materials and the variability of downstream demand. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention proposes a process method and device for positive pressure biomass gasification and co-production of charcoal, which can adjust the ratio of biomass fuel gas and biomass charcoal in the gasification product to achieve the purpose of meeting the adaptability of raw materials and downstream market demand.

[0006] To achieve the above-mentioned purpose, the present invention is a process for positive pressure biomass gasification and co-production of charcoal, which is used to adjust the output ratio of biomass gas and biomass charcoal, and its special feature is that it includes the following steps:

[0007] S1) transporting the finely crushed biomass fuel to the furnace silo;

[0008] S2) The finely pulverized biomass fuel is fed into the fluidized bed gasifier through the positive pressure feeding system in front of the furnace, and the bed material is replenished for the fluidized bed gasifier at any time through the bed material supply system as needed;

[0009] S3) The biomass fuel is gasified under the action of the centrifugal fan at the bottom of the fluidized bed gasifier, and the supply of fluidizing air and air gasifying agent is adjusted by the variable frequency centrifugal fan, and the temperature of the fluidized bed gasifier is adjusted, thereby adjusting the ratio of the generated gasification fuel gas and biomass charcoal;

[0010] When the air volume of the centrifugal fan is controlled at 25% to 45% of the theoretical air volume required for complete combustion of the biomass entering the furnace, the fluidized bed gasifier is in a gasification condition;

[0011] When the air volume of the centrifugal fan is controlled at 15% to 25% of the theoretical air volume required for complete combustion of the biomass entering the furnace, the fluidized bed gasifier is in a charcoal production condition;

[0012] The theoretical amount of air required for complete combustion of biomass is obtained by the following formula:

[0013] V=0.0889×C wt％ +0.267H wt％ +0.033×(S wt％ -O wt％ )

[0014] In the formula,

[0015] V is the theoretical amount of air required for complete combustion of 1 kg of biomass, in Nm 3 ,

[0016] C wt％ , H wt％ , S wt％ , O wt％ They are the elemental analysis composition ratios of carbon, hydrogen, sulfur, and oxygen in biomass;

[0017] S4) the blocky biomass char falls into the bottom of the fluidized bed gasifier and is collected and utilized through the slag discharge system;

[0018] The ash-like biomass char is captured by the primary cyclone separator and the secondary cyclone separator at the upper end of the fluidized bed gasifier, and sinks in the primary cyclone separator and the secondary cyclone separator, and enters the ash discharge system, and is collected and utilized by the ash discharge system;

[0019] The gasification gas enters the primary cyclone separator and the secondary cyclone separator in sequence from the upper end of the fluidized bed gasifier, and after being separated in the primary cyclone separator and the secondary cyclone separator, enters the gas transmission system and is transported to users through the gas transmission system.

[0020] Furthermore, in S1), the finely chopped biomass fuel is transported to the silo in front of the furnace by a belt conveyor, so as to achieve the purpose of large-scale continuous operation of the fluidized bed gasification furnace.

[0021] Furthermore, in S4), when the distance to the downstream gas user is relatively close, the gas transmission system directly transports the gas to the user through the carbon steel pipe cast refractory material; when the distance to the downstream gas user is relatively far, the gas transmission system lowers the gas temperature through the thermal oil heat exchanger before transporting the gas to the user.

[0022] Furthermore, in S4), when the downstream gas user is far away, the gas transmission system cools the gas to 400-450° C. before transmission.

[0023] The present invention also provides a positive pressure biomass gasification and charcoal co-production device, including a fluidized bed gasifier, which is particularly characterized in that:

[0024] The middle part of one side of the fluidized bed gasifier is connected to a bed material supply system, the lower part of one side is connected to a furnace front positive pressure feeding system, the upper part of the other side is connected to a primary cyclone separator, the bottom end of the primary cyclone separator is connected to a return device, and the return device is connected to the fluidized bed gasifier, the upper part of the primary cyclone separator is connected to a secondary cyclone separator, and the bottom ends of the primary cyclone separator and the secondary cyclone separator are respectively connected to ash removal systems;

[0025] The top of the secondary cyclone separator is connected to a gas delivery system;

[0026] The bottom of the fluidized bed gasification furnace is connected to a slag discharge system and a centrifugal fan capable of regulating wind speed.

[0027] Furthermore, the bed material supply system includes a bucket elevator for lifting bed material, and a bed material bin for temporarily storing bed material is provided at the outlet end of the bucket elevator. The bottom end of the bed material bin is connected to a pneumatic conveying bin pump, and the outlet of the pneumatic conveying bin pump is connected to the middle of one side of the fluidized bed gasifier.

[0028] Furthermore, the front-of-furnace positive-pressure feeding system includes a fuel conveying system, a front-of-furnace silo is provided at the outlet end of the fuel conveying system, a center feeder is provided at the bottom end of the front-of-furnace silo, a metering screw is provided at the bottom end of the center feeder, a positive-pressure sealed rotary feeding valve is provided at the outlet end of the metering screw, and the positive-pressure sealed rotary feeding valve provides sealing air through a Roots blower, the outlet end of the positive-pressure sealed rotary feeding valve is connected to a positive-pressure water-cooled screw conveyor, and the outlet end of the positive-pressure water-cooled screw conveyor is connected to the lower part of one side of the fluidized bed gasification furnace.

[0029] Furthermore, the fuel conveying system includes a belt conveyor for conveying finely chopped biomass fuel, and the belt conveyor conveys the biomass fuel to the furnace silo.

[0030] Furthermore, the ash removal system includes an ash falling pipe which is arranged vertically at the bottom of the primary cyclone separator and the secondary cyclone separator, the outlet end of the ash falling pipe is connected to an ash cooler, and the outlet of the ash cooler is provided with a biomass carbon powder packaging and conveying system.

[0031] Furthermore, the slag discharge system comprises a slag discharge port arranged at the bottom end of the fluidized bed gasifier, the outlet of the slag discharge port is connected to a vertically arranged slag discharge pipe, and the outlet of the slag discharge pipe is connected to a spiral slag cooler.

[0032] The advantages of the present invention are:

[0033] 1. The present invention adjusts the supply of fluidizing air and air gasifying agent by a variable frequency fluidizing fan, thereby adjusting the temperature of the gasifier, achieving the purpose of adjusting the product ratio of biogas and biochar, and can better adapt to changes in downstream gasification gas and biochar demand, as well as changes in upstream biomass fuel;

[0034] 2. The device of the present invention operates under positive pressure, avoiding the risk of gas flash explosion caused by air leakage. Compared with negative pressure, it is safer and more reliable, eliminating the need for high-temperature booster fans in the subsequent gas transmission section, and saving the overall construction cost.

[0035] The positive pressure biomass gasification and charcoal co-production process method and device of the present invention operate under positive pressure, can adjust the output ratio of biomass gas and biomass charcoal in the gasification product, and better adapt to changes in downstream gas and biomass charcoal demand, as well as changes in upstream biomass fuel. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the layout of the positive pressure biomass gasification and charcoal co-production device of the present invention;

[0037] In the figure: bed material supply system 1, belt conveyor 2, furnace front silo 3, central material taker 4, metering screw 5, Roots blower 6, positive pressure sealed rotary feed valve 7, positive pressure water-cooled screw conveyor 8, centrifugal fan 9, slag discharge system 10, fluidized bed gasifier 11, primary cyclone separator 12, secondary cyclone separator 13, fuel gas delivery system 14, ash discharge system 15;

[0038] The bed material supply system 1 comprises: a bucket elevator 1-1, a bed material bin 1-2, and a pneumatic conveying bin pump 1-3;

[0039] The slag discharge system 10 includes: a slag discharge port 10-1, a slag discharge pipe 10-2, and a spiral slag cooler 10-3;

[0040] The primary cyclone separator 12 comprises: a material return device 12-1;

[0041] The ash discharge system 15 includes an ash drop pipe 15-1 and an ash cooler 15-2. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0043] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention.

[0044] The present invention designs a positive pressure biomass gasification and charcoal co-production device, including a fluidized bed gasifier 11, wherein the middle part of one side of the fluidized bed gasifier 11 is connected to a bed material supply system 1, the lower part of one side is connected to a furnace front positive pressure feeding system, and the upper part of the other side is connected to a primary cyclone separator 12, the bottom end of the primary cyclone separator 12 is connected to a return device 12-1, and the return device 12-1 is connected to the fluidized bed gasifier 11, the upper part of the primary cyclone separator 12 is connected to a secondary cyclone separator 13, the bottom ends of the primary cyclone separator 12 and the secondary cyclone separator 13 are respectively connected to an ash removal system 15; the top of the secondary cyclone separator 13 is connected to a fuel gas delivery system 14; the bottom of the fluidized bed gasifier 11 is connected to a slag removal system 10 and a centrifugal fan 9 capable of regulating wind speed.

[0045] The centrifugal fan 9 is used to provide fuel fluidizing air and also serves as an air gasifying agent.

[0046] Preferably, the bed material supply system includes a bucket elevator 1-1 for lifting bed material, and a bed material bin 1-2 for temporarily storing bed material is provided at the outlet end of the bucket elevator 1-1. The bottom end of the bed material bin 1-2 is connected to a pneumatic conveying bin pump 1-3, and the outlet of the pneumatic conveying bin pump 1-3 is connected to the middle of one side of the fluidized bed gasifier 11.

[0047] The furnace front positive pressure feeding system is a positive pressure sealing conveying system that conveys the biomass fuel from the furnace front silo 3 to the fluidized bed gasification furnace 11 .

[0048] Preferably, the front-of-furnace positive-pressure feeding system includes a fuel conveying system, the outlet end of the fuel conveying system is provided with a front-of-furnace silo 3, the bottom end of the front-of-furnace silo 3 is provided with a center feeder 4, the bottom end of the center feeder 4 is provided with a metering screw 5, the outlet end of the metering screw 5 is provided with a positive-pressure sealed rotary feeding valve 7, and the positive-pressure sealed rotary feeding valve 7 provides sealing air through a Roots blower 6, the outlet end of the positive-pressure sealed rotary feeding valve 7 is connected to a positive-pressure water-cooled screw conveyor 8, and the outlet end of the positive-pressure water-cooled screw conveyor 8 is connected to the lower part of one side of the fluidized bed gasification furnace 11.

[0049] In this embodiment, a gasification system with a biomass fuel processing capacity of 15 t / h is used as an example. The biomass fuel is agricultural and forestry waste (including rice husks, straw, sawdust, etc.), with a particle size of 5 to 20 mm, a moisture content of 20%, and a lower calorific value of 3117 kcal / kg. According to elemental analysis, the carbon content of biomass is C wt％ The hydrogen content is 37.02%. wt％ The oxygen content is 4.7%, and the oxygen content is C wt％ The sulfur content is 35.33%. wt％ It is 0.1%.

[0050] Preferably, the fuel conveying system comprises a belt conveyor 2 for conveying finely chopped biomass fuel, and the belt conveyor 2 conveys the biomass fuel to the furnace front silo 3.

[0051] The belt conveyor 2 can also be a plate chain feeder or a screw conveyor.

[0052] In this embodiment, the biomass fuel is transported to the fuel dry material shed (5000m 3 ) for unloading, the loader loads the material into the hopper, and then connects to the double screw conveyor or chain plate feeder, and then sends it to the belt conveyor 2 and transports it to the furnace silo 3 (50m 3 ).

[0053] Preferably, the ash removal system 15 includes an ash dropping pipe 15-1 which is arranged vertically at the bottom of the primary cyclone separator 12 and the secondary cyclone separator 13, and the outlet end of the ash dropping pipe 15-1 is connected to an ash cooler 15-2, and the outlet of the ash cooler 15-2 is provided with a biomass carbon powder packaging and conveying system.

[0054] After the two ash dropping pipes 15-1 at the bottom of the primary cyclone separator 12 and the secondary cyclone separator 13 are merged, they are cooled by the ash cooler 15-2 to obtain biomass charcoal powder, which is packaged and sent to a temporary storage.

[0055] Preferably, the slag discharge system 10 comprises a slag discharge port 10-1 arranged at the bottom end of the fluidized bed gasifier 11, the outlet of the slag discharge port 10-1 is connected to a vertically arranged slag discharge pipe 10-2, and the outlet of the slag discharge pipe 10-2 is connected to a spiral slag cooler 10-3.

[0056] Specifically, the slag discharge port 10-1 is arranged in the middle of the air distribution plate at the bottom of the gasifier. After the biomass char enters the spiral slag cooler 10-3 for cooling through the slag discharge, a biomass charcoal block can be obtained and sent to a temporary storage.

[0057] The positive pressure biomass gasification and charcoal co-production process of the present invention is used to adjust the output ratio of biomass gas and biomass charcoal, and comprises the following steps:

[0058] S1) The finely pulverized biomass fuel is transported to the furnace silo 3.

[0059] Specifically, the finely chopped biomass fuel is transported to the furnace silo 3 by the belt conveyor 2, so that the fluidized bed gasification furnace 11 can achieve large-scale continuous operation.

[0060] After the biomass fuel that meets the requirements (including agricultural and forestry wastes such as rice husks, straw, and wood chips) is transported to the drying shed by a transfer vehicle, it is loaded into the hopper by a loader, and the hopper is connected to a screw feeder or a plate chain loader, and then transported to the belt conveyor 2, and unloaded into the furnace silo 3 through a plow-type unloader or a head funnel.

[0061] S2) The finely pulverized biomass fuel is fed into the fluidized bed gasifier 11 through the positive pressure feeding system in front of the furnace, and the bed material is replenished for the fluidized bed gasifier 11 at any time through the bed material supply system 1 as needed.

[0062] The biomass fuel is fed into the metering screw 5 below by the central feeder 4 at the bottom of the silo 3 in front of the furnace, and then passes through the vertical pipe of the two-stage positive pressure sealed rotary feeding valve 7 below. The sealing air is provided by the Roots blower 6, and finally is fed into the gasifier by the positive pressure water-cooled screw conveyor 8.

[0063] The bed material supply system replenishes bed material at any time as needed to keep the pressure in the gasifier wind chamber constant. Boiler bottom ash from a coal-fired power plant or river sand can be used as bed material. The bed material is transported to a bed material silo 1-2 for bed material buffering by a bucket elevator 1-1, and then transported to the fluidized bed gasifier 11 by a pneumatic conveying silo pump 1-3.

[0064] S3) The biomass fuel is gasified under the action of the centrifugal fan 9 at the bottom of the fluidized bed gasifier 11. The frequency-variable centrifugal fan 9 adjusts the supply of fluidizing air and air gasifying agent, thereby adjusting the temperature of the fluidized bed gasifier 11, thereby adjusting the ratio of the generated gasification fuel gas and biomass charcoal.

[0065] When the air volume of the centrifugal fan is controlled at 25% to 45% of the theoretical air volume required for complete combustion of the biomass entering the furnace (ie, the excess air coefficient is controlled at 0.25 to 0.45), the fluidized bed gasifier is in a gasification condition.

[0066] When the air volume of the centrifugal fan is controlled at 15% to 25% of the theoretical air volume required for complete combustion of the biomass entering the furnace (ie, the excess air coefficient is controlled at 0.15 to 0.25), the fluidized bed gasifier is in a charcoal production condition.

[0067] The theoretical amount of air required for complete combustion of biomass is obtained by the following formula:

[0068] V=0.0889×C wt％ +0.267H wt％ +0.033×(S wt％ -O wt％ )

[0069] In the formula,

[0070] V is the theoretical amount of air required for complete combustion of 1 kg of biomass, in Nm 3 ,

[0071] C wt％ , H wt％ , S wt％ , O wt％ They are the elemental analysis composition ratios of carbon, hydrogen, sulfur and oxygen in biomass respectively.

[0072] After the biomass fuel enters the fluidized bed gasifier 11, it is gasified under the action of the centrifugal fan 9 at the bottom of the furnace. When the fluidized bed gasifier 11 is undergoing gasification reaction, the furnace temperature is about 680°C-800°C, and a small amount of biomass charcoal can be co-produced at this time; when the air volume of the centrifugal fan 9 at the bottom of the furnace is reduced, the furnace temperature is reduced to about 600°C, and the output of biomass charcoal is significantly increased.

[0073] In this embodiment, the centrifugal fan 9 at the bottom of the gasifier has a wind pressure of 30 kPa and a wind volume of 20000 Nm 3 / h. The temperature of the gasifier is 680℃-800℃. After gasification, the flow rate of synthetic gas is about 32000Nm 3 / h, calorific value is about 5.8MJ / Nm 3 .

[0074] In this embodiment, according to calculation, the theoretical air volume required for complete combustion of 1 kg of biomass is V = 3.36 Nm 3 If 15t of biomass is put into the furnace per hour, the theoretical air volume V required is 50400Nm 3 The air volume of the fan is 0.3V~0.45V, that is, 15120Nm 3 / h~22680Nm 3 / h.

[0075] In this embodiment, the gasification bottom ash is about 2.1t / d, and the gasification fly ash captured by the first-stage cyclone separator 12 and the second-stage cyclone separator 13 is about 9.8t / d. After cooling by the spiral slag cooler 10-3 and the ash cooler 15-2, 2.1 tons of small block biochar and 9.8 tons of biochar powder are obtained every day. The biochar and charcoal powder can be comprehensively utilized as soil conditioners.

[0076] When the fluidized bed gasifier 11 is adjusted to the charcoal production mode, the air volume of the centrifugal fan 9 can be reduced and the excess air coefficient can be controlled at 0.15-0.25, that is, the air volume of the fan can be adjusted to control the air volume to 15%-25% of the theoretical air volume required for complete combustion of the biomass entering the furnace, that is, 7560Nm 3 / h~12600Nm 3 / h. According to actual engineering experience, under this working condition, the gasifier temperature is approximately 580℃-630℃.

[0077] The gasification bottom ash is about 4.3t / d, and the gasification fly ash captured by the primary cyclone separator 12 and the secondary cyclone separator 13 is about 11.5t / d. After being cooled by the spiral slag cooler 10-3 and the ash cooler 15-2, 4.3 tons of small block biochar and 11.5 tons of biochar powder can be obtained every day.

[0078] S4) The blocky biochar falls into the bottom of the fluidized bed gasifier 11 and is collected and utilized by the slag discharge system 10. The bottom slag of the fluidized bed gasifier 11 is cooled by a spiral slag cooler 10-3 to obtain small blocks of biochar.

[0079] The ash-like biomass char is captured by the primary cyclone separator 12 and the secondary cyclone separator 13 at the upper end of the fluidized bed gasifier 11, and sinks in the primary cyclone separator 12 and the secondary cyclone separator 13, and enters the ash discharge system 15, and is collected and utilized by the ash discharge system 15. The fly ash of the gasifier is captured by the primary cyclone separator 12 and the secondary cyclone separator 13, and enters the ash cooler 15-2 for cooling. After cooling, the biomass charcoal powder is obtained, which is packaged, stored and transported.

[0080] The gasification gas enters the primary cyclone separator 12 and the secondary cyclone separator 13 in sequence from the upper end of the fluidized bed gasifier 11 , and after being separated in the primary cyclone separator 12 and the secondary cyclone separator 13 , enters the gas transportation system 14 , and is transported to users through the gas transportation system 14 .

[0081] The gas generated by the gasifier is directly transported to the subsequent coal-fired power plant boiler or industrial kiln through a pipeline and used as fuel gas. The gas temperature delivered by the gas delivery system is about 700°C, and the system does not need to be equipped with a high-temperature booster fan. When the downstream gas user is close, the gas delivery system 14 is directly delivered to the user through a carbon steel pipe cast refractory material; when the downstream gas user is far away, the gas delivery system 14 is to reduce the gas temperature through a thermal oil heat exchanger before delivering it to the user.

[0082] Specifically, when the downstream gas user is far away, the gas transmission system 14 cools the gas to 400-450° C. before transmission.

[0083] The positive pressure biomass gasification and charcoal co-production process method and device of the present invention operate under positive pressure, can adjust the output ratio of biomass gas and biomass charcoal in the gasification product, and better adapt to changes in downstream gas and biomass charcoal demand, as well as changes in upstream biomass fuel.

[0084] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A positive pressure biomass gasification and charcoal co-production process, used to adjust the output ratio of biomass gas and biomass charcoal, characterized in that: The steps include: S1) transporting the finely pulverized biomass fuel to the furnace silo (2); S2) The finely pulverized biomass fuel is fed into the fluidized bed gasifier (11) through a positive pressure feeding system in front of the furnace, and the bed material is replenished for the fluidized bed gasifier (11) at any time through a bed material supply system (1) as needed; S3) the biomass fuel is gasified under the action of the centrifugal fan (9) at the bottom of the fluidized bed gasification furnace (11), and the supply amount of fluidizing air and air gasification agent is adjusted by the variable frequency centrifugal fan (9), and the temperature of the fluidized bed gasification furnace (11) is adjusted, thereby adjusting the ratio of the generated gasification fuel gas and biomass charcoal; When the air volume of the centrifugal fan is controlled at 25% to 45% of the theoretical air volume required for complete combustion of the biomass entering the furnace, the fluidized bed gasifier is in a gasification condition; When the air volume of the centrifugal fan is controlled at 15% to 25% of the theoretical air volume required for complete combustion of the biomass entering the furnace, the fluidized bed gasifier is in a charcoal production condition; The theoretical amount of air required for complete combustion of biomass is obtained by the following formula: V=0.0889×C wt％ +0.267H wt％ +0.033×(S wt％ -O wt％ ) In the formula, V is the theoretical amount of air required for complete combustion of 1 kg of biomass, in Nm 3 , C wt％ , H wt％ , S wt％ , O wt％ They are the elemental analysis composition ratios of carbon, hydrogen, sulfur, and oxygen in biomass; S4) the lump biomass char falls into the bottom of the fluidized bed gasifier (11) and is collected and utilized through the slag discharge system (10); The ash-like biomass char is captured at the upper end of the fluidized bed gasifier (11) by a primary cyclone separator (12) and a secondary cyclone separator (13), and sinks in the primary cyclone separator (12) and the secondary cyclone separator (13), and enters an ash discharge system (15), and is collected and utilized by the ash discharge system (15); The gasified gas enters the primary cyclone separator (12) and the secondary cyclone separator (13) in sequence from the upper end of the fluidized bed gasifier (11), is separated in the primary cyclone separator (12) and the secondary cyclone separator (13), and then enters the gas transmission system (14), and is transported to users through the gas transmission system (14).

2. The process for co-production of charcoal by positive pressure biomass gasification according to claim 1, characterized in that: In S1), the finely pulverized biomass fuel is transported to the furnace silo (3) by a belt conveyor (2), thereby achieving the purpose of large-scale continuous operation of the fluidized bed gasification furnace (11).

3. The process for co-production of charcoal by positive pressure biomass gasification according to claim 2, characterized in that: In S4), when the distance to the downstream gas user is relatively close, the gas delivery system (14) directly delivers the gas to the user through a carbon steel pipe cast with refractory material; when the distance to the downstream gas user is relatively far, the gas delivery system (14) lowers the gas temperature through a thermal oil heat exchanger before delivering the gas to the user.

4. The process for co-production of charcoal by positive pressure biomass gasification according to claim 3 is characterized by: In S4), when the downstream gas user is far away, the gas transmission system (14) cools the gas to 400-450°C before transmission.

5. A positive pressure biomass gasification and charcoal co-production device, comprising a fluidized bed gasifier (11), characterized in that: The middle part of one side of the fluidized bed gasification furnace (11) is connected to a bed material supply system (1), the lower part of one side is connected to a furnace front positive pressure feeding system, and the upper part of the other side is connected to a primary cyclone separator (12), the bottom end of the primary cyclone separator (12) is connected to a return device (12-1), and the return device (12-1) is connected to the fluidized bed gasification furnace (11), the upper part of the primary cyclone separator (12) is connected to a secondary cyclone separator (13), and the bottom ends of the primary cyclone separator (12) and the secondary cyclone separator (13) are respectively connected to ash removal systems (15); The top end of the secondary cyclone separator (13) is connected to a gas delivery system (14); The bottom of the fluidized bed gasification furnace (11) is connected to a slag discharge system (10) and a centrifugal fan (9) capable of regulating wind speed.

6. The positive pressure biomass gasification and charcoal co-production device according to claim 5, characterized in that: The bed material supply system (11) comprises a bucket elevator (1-1) for lifting bed material, the outlet end of the bucket elevator (1-1) is provided with a bed material bin (1-2) for temporarily storing bed material, the bottom end of the bed material bin (1-2) is connected to a pneumatic conveying bin pump (1-3), and the outlet of the pneumatic conveying bin pump (1-3) is connected to the middle of one side of the fluidized bed gasifier (11).

7. The positive pressure biomass gasification and charcoal co-production device according to claim 6, characterized in that: The furnace front positive pressure feeding system comprises a fuel conveying system, wherein the outlet end of the fuel conveying system is provided with a furnace front material bin (3), the bottom end of the furnace front material bin (3) is provided with a central feeder (4), the bottom end of the central feeder (4) is provided with a metering screw (5), the outlet end of the metering screw (5) is provided with a positive pressure sealing rotary feeding valve (7), and the positive pressure sealing rotary feeding valve (7) provides sealing air through a Roots blower (6), the outlet end of the positive pressure sealing rotary feeding valve (7) is connected to a positive pressure water-cooling screw conveyor (8), and the outlet end of the positive pressure water-cooling screw conveyor (8) is connected to the lower part of one side of the fluidized bed gasification furnace (11).

8. The positive pressure biomass gasification and charcoal co-production device according to claim 7, characterized in that: The fuel conveying system comprises a belt conveyor (2) for conveying finely chopped biomass fuel, and the belt conveyor (2) conveys the biomass fuel to a furnace silo (3).

9. The positive pressure biomass gasification and charcoal co-production device according to claim 8, characterized in that: The ash discharge system (15) comprises an ash drop pipe (15-1) which is arranged at the bottom end of the primary cyclone separator (12) and the secondary cyclone separator (13) and is arranged vertically, the outlet end of the ash drop pipe (15-1) is connected to an ash cooler (15-2), and the outlet of the ash cooler (15-2) is provided with a biomass carbon powder packaging and conveying system.

10. The positive pressure biomass gasification and charcoal co-production device according to claim 9, characterized in that: The slag discharge system (10) comprises a slag discharge port (10-1) arranged at the bottom end of the fluidized bed gasification furnace (11), the outlet of the slag discharge port (10-1) is connected to a vertically arranged slag discharge pipe (10-2), and the outlet of the slag discharge pipe (10-2) is connected to a spiral slag cooler (10-3).

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