Biomass low-temperature pyrolysis system based on positive pressure smoke exhaust

Abstract

The utility model relates to a biomass low-temperature pyrolysis system based on positive pressure smoke discharge. The biomass low-temperature pyrolysis system comprises a non-contact one-way sealed smoke collection system and a rotary pyrolysis furnace, the non-contact one-way sealed flue gas collection system comprises a gas extraction pipeline and an exhaust fan installed on the gas extraction pipeline, a gas inlet of the gas extraction pipeline is located obliquely above the one-way gas outlet, and the gas inlet of the gas extraction pipeline is located on the side, away from the rotary pyrolyzing furnace, of the one-way gas outlet in the flue gas flowing direction; a gas-solid separation area is formed between the air inlet and the one-way air outlet of the air exhaust pipeline, under the action of the exhaust fan, smoke exhausted by the rotary pyrolyzing furnace and air in the gas-solid separation area enter the air exhaust pipeline, and the smoke exhausted by the rotary pyrolyzing furnace is cooled through the air. And oxygen backflow is prevented by utilizing self-generated positive pressure in the furnace and a non-contact gas collecting system, so that the problem of spontaneous combustion of products caused by oxygen permeation in the low-temperature pyrolysis process of the biomass is effectively solved.

Description

Technical Field

[0001] This utility model relates to the field of biomass pyrolysis technology, and in particular to the precise controlled pyrolysis of biomass at low temperatures and the efficient collection of pyrolysis products. Specifically, it refers to a low-temperature biomass pyrolysis system based on positive pressure flue gas exhaust. Background Technology

[0002] Rotary pyrolysis equipment is widely used in drying and biomass pyrolysis. During biomass pyrolysis, the biomass loaded into the equipment is pyrolyzed by heating the equipment and rotating it.

[0003] Currently, mainstream biomass pyrolysis aims to carbonize biomass to obtain biochar, pyrolysis gas, and wood tar, and the pyrolysis process is high-temperature pyrolysis. Since biomass pyrolysis at medium and low temperatures (180-250℃) requires an anaerobic environment, the introduction of air or oxygen during this process can easily trigger spontaneous combustion, making medium and low-temperature pyrolysis more difficult. Currently, there is no equipment specifically designed to collect the flue gas generated during medium and low-temperature pyrolysis.

[0004] Furthermore, when collecting the flue gas generated during pyrolysis, the high temperature of the flue gas causes the subsequent flue gas treatment system to operate in a high-temperature environment, which is not conducive to extending the service life of the equipment. Utility Model Content

[0005] This invention addresses the shortcomings of existing technologies by providing a low-temperature biomass pyrolysis system based on positive pressure flue gas exhaust. This system not only prevents external gases from entering the furnace during pyrolysis but also reduces the temperature of the flue gas entering the flue gas treatment equipment.

[0006] This utility model is achieved through the following technical solution: a low-temperature biomass pyrolysis system based on positive pressure flue gas exhaust is provided, including a non-contact unidirectional sealed flue gas collection system and a rotary pyrolysis furnace equipped with a heating device. One end of the rotary pyrolysis furnace is provided with a sealed feed port, and the other end of the rotary pyrolysis furnace is provided with a unidirectional exhaust port. The non-contact unidirectional sealed flue gas collection system includes an exhaust pipe and an exhaust fan installed on the exhaust pipe. The air inlet of the exhaust pipe is located obliquely above the unidirectional exhaust port along the flue gas flow direction, on the side of the unidirectional exhaust port away from the rotary pyrolysis furnace. A gas-solid separation zone is formed between the air inlet and the unidirectional exhaust port of the exhaust pipe. Under the action of the exhaust fan, the flue gas discharged from the rotary pyrolysis furnace and the air in the gas-solid separation zone enter the exhaust pipe, and the air is used to cool the flue gas discharged from the rotary pyrolysis furnace.

[0007] This solution uses a rotary pyrolysis furnace with one end sealed and the other end having a one-way outlet, creating a positive pressure inside the furnace during pyrolysis. Gas is only discharged from inside the furnace to the outside, preventing external oxygen-containing gas from entering the furnace and causing spontaneous combustion. The non-contact one-way sealed flue gas collection system uses the pressure difference generated by the exhaust fan to draw the flue gas discharged from the pyrolysis furnace into the exhaust pipe, further preventing oxygen-containing gas from entering the furnace. At the same time, the air entering the exhaust pipe is used to cool the flue gas, and large dust particles carried in the flue gas fall off in the gas-solid separation zone.

[0008] As an optimization, the sealed feed inlet includes a furnace door detachably fixed to the rotary pyrolysis furnace, and a graphite packing disposed between the furnace door and the rotary pyrolysis furnace. In this optimized design, the sealed feed inlet can be opened for easy loading, and after the furnace door is closed, the graphite packing ensures a tight seal.

[0009] As an optimization, a water inlet is provided on the furnace door, and a removable sealing plug is installed inside the water inlet. This optimization scheme, by providing a water inlet, facilitates the injection of water into the rotary pyrolysis furnace after pyrolysis, so as to quickly cool the biomass inside the furnace and prevent spontaneous combustion after the furnace door is opened.

[0010] As an optimization, a dust collector is also installed on the exhaust duct, and the dust collector is located upstream of the exhaust fan along the airflow direction. This optimized solution removes dust from the flue gas by setting up a dust collector, thus avoiding environmental pollution. Placing the dust collector upstream of the exhaust fan prevents dust in the flue gas from clogging the exhaust fan.

[0011] As an optimization, the axis of the unidirectional gas outlet coincides with the rotation axis of the rotary pyrolysis furnace, and the unidirectional gas outlet extends 10cm~15cm beyond the rotary pyrolysis furnace. This optimized scheme places the unidirectional gas outlet at the rotation center of the rotary furnace, which can better ensure the formation of effective positive pressure inside the rotary pyrolysis furnace. Setting the unidirectional gas outlet to protrude 10-15cm from the furnace body can prevent air from entering the furnace due to gas vortices generated by the furnace rotation.

[0012] As an optimization, the distance between the air inlet of the extraction pipe and the one-way air outlet is 15cm to 20cm. This optimized distance setting ensures that the flue gas discharged from the one-way air outlet enters the extraction pipe, while also allowing large dust particles contained in the flue gas to fall off before entering the extraction pipe.

[0013] As an optimization, the heating device includes an insulating outer shell that circumferentially covers the rotary pyrolysis furnace, and an electric heating jacket disposed within the insulating outer shell. A thermocouple is installed between the electric heating jacket and the furnace wall of the rotary pyrolysis furnace. This optimized solution heats the rotary pyrolysis furnace through the electric heating jacket. The insulating outer shell provides protection for the electric heating jacket and reduces heat loss. The thermocouple facilitates monitoring the heating temperature of the electric heating jacket, enabling precise temperature control.

[0014] As an optimization, a probe extending into the rotary pyrolysis furnace is inserted through the unidirectional gas outlet, and a temperature sensor is installed at one end of the probe extending into the rotary pyrolysis furnace. This optimized solution, by setting a temperature sensor, facilitates the detection of the temperature inside the rotary pyrolysis furnace, and by setting a probe, it is easier to position the temperature sensor in the middle of the furnace, which is more conducive to precise temperature control.

[0015] As an optimization, the exhaust pipe's outlet is connected to a smoke collection tower, which contains a water spray system. The bottom of the smoke collection tower is connected to a filtration system via a drain pipe, and the top of the smoke collection tower has an exhaust vent equipped with a gas detection probe. This optimized solution uses water sprayed from the water spray system to scrub the flue gas entering the smoke collection tower. The scrubbing water then flows through the drain pipe into the filtration system for filtration. Gases insoluble in water and water vapor are discharged through the top exhaust vent. The gas detection probe detects harmful gases, allowing for timely closure of the exhaust vent to prevent their release.

[0016] This solution also provides a method for using a biomass low-temperature pyrolysis system based on positive pressure flue gas exhaust, characterized by the following steps:

[0017] a. Load the biomass into the rotary pyrolysis furnace and close the sealed feed inlet;

[0018] b. The rotary pyrolysis furnace body rotates at 5-10 r / min. At the same time, the heating device heats the rotary pyrolysis furnace. When the temperature inside the furnace reaches 100℃, the biomass produces water vapor, which creates positive pressure inside the furnace. The water vapor displaces the air inside the furnace, creating an oxygen-deficient micro-positive pressure environment inside the furnace, preventing outside air from entering the furnace.

[0019] c. When the furnace temperature reaches 160-180℃, pyrolysis begins, and the flue gas generated by pyrolysis is discharged through the one-way outlet. At this time, the exhaust fan is turned on. Under the action of pressure difference, the flue gas discharged through the one-way outlet and the air in the gas-solid separation zone enter the exhaust pipe, preventing outside air from entering the rotary pyrolysis furnace through the one-way inlet. The gas-solid separation zone is used to make large dust particles carried in the flue gas fall off before entering the exhaust pipe.

[0020] d. The flue gas is cooled by the air entering the extraction pipe. After being cooled, the flue gas enters the smoke collection tower after being dusted by the dust collector. The flue gas is washed by the water spray system installed in the smoke collection tower. Insoluble gases and water vapor are discharged from the top of the smoke collection tower. The water after washing the flue gas is discharged from the bottom of the smoke collection tower and enters the filtration system for filtration.

[0021] e. After pyrolysis is complete, turn off the exhaust fan, open the sealing plug of the water inlet of the furnace door, and spray water into the rotary pyrolysis furnace through the water inlet to reduce the temperature inside the furnace.

[0022] The beneficial effects of this utility model are as follows:

[0023] 1. This utility model utilizes the positive pressure inside the furnace caused by the gas generated by pyrolysis to achieve one-way sealing of the furnace body, which can ensure that no external gas enters during the rotary pyrolysis furnace rotation heating process, guarantee an oxygen-deficient environment inside the furnace, and improve the production safety factor.

[0024] 2. This utility model directly inserts the temperature control probe through the one-way air outlet to measure the temperature at the center of the furnace body, ensuring the accuracy of temperature measurement and solving the problems of complex structure, high failure rate and insufficient accuracy of temperature measurement in traditional methods using slip rings.

[0025] 3. The non-contact unidirectional sealed flue gas collection system of this utility model extracts a large amount of ambient air while extracting flue gas, and uses the air to quickly cool down the high-temperature flue gas, so that the subsequent exhaust fan, smoke collection tower and filtration system are not allowed to work in a high-temperature environment, thus extending the service life of the equipment. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the process structure of this utility model;

[0027] Figure 2 This is a schematic diagram showing the relative positions of the unidirectional air outlet and the air extraction pipe of this utility model;

[0028] As shown in the figure:

[0029] 1. Rotary pyrolysis furnace; 2. Electric heating jacket; 3. One-way gas outlet; 4. Exhaust pipe; 5. Dust collector; 6. Dust collection tank; 7. Dust outlet; 8. Exhaust fan; 9. Smoke collection tower; 10. Gas detection probe; 11. Inspection port; 12. Temperature sensor; 13. Thermocouple; 14. Control system; 15. Filter rod; 16. Water pump; 17. Water inlet; 18. Insulation shell; 19. Liquid outlet valve; 20. Graphite packing; 21. Furnace door; 22. Rupture disc; 23. Sealed feed inlet. Detailed Implementation

[0030] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0031] like Figure 1 The present invention discloses a biomass low-temperature pyrolysis system based on positive pressure flue gas exhaust, including a non-contact one-way sealed flue gas collection system and a rotary pyrolysis furnace 1 equipped with a heating device. The furnace body structure of the rotary pyrolysis furnace can adopt existing technology. The furnace body of the rotary pyrolysis furnace is a horizontal cylindrical shape. The furnace body is driven to rotate around the horizontal axis by a drive device. The inner wall of the furnace body is equipped with rupture discs 22.

[0032] One end of the rotary pyrolysis furnace 1 is provided with a sealed feed inlet 23, and the other end of the rotary pyrolysis furnace 1 is provided with a one-way gas outlet 3. The gas outlet direction of the one-way gas outlet is from inside the rotary pyrolysis furnace to outside the rotary pyrolysis furnace, so as to prevent external gas from entering the furnace body.

[0033] The sealed feed inlet 23 includes a furnace door 21 detachably fixed to the rotary pyrolysis furnace, and a graphite packing 20 disposed between the furnace door 21 and the rotary pyrolysis furnace. The furnace door can be hinged to the furnace body or fixed with bolts. When the furnace door is open, it facilitates the placement of materials into the furnace; when the furnace door is closed, it is sealed by the graphite packing. The graphite packing 20 is made of high-temperature resistant graphite braided material, with a sealing pressure ≥0.1MPa and a temperature resistance ≥300℃.

[0034] The furnace door is circular, with a water inlet 17 at its center. The diameter of the water inlet is less than 2 cm. A detachable sealing plug is installed inside the water inlet 17. In this embodiment, the sealing plug is threaded to the side wall of the water inlet for sealing. During pyrolysis, the water inlet is sealed with the sealing plug. After pyrolysis, water is injected into the rotating pyrolysis furnace through the water inlet to rapidly cool the furnace.

[0035] The heating device includes an insulating outer shell 18 that is circumferentially wrapped around the rotary pyrolysis furnace, and an electric heating jacket 2 disposed inside the insulating outer shell. The electric heating jacket adopts existing technology and is equipped with an electric heating tube. A thermocouple 13 is disposed between the electric heating jacket 2 and the furnace wall of the rotary pyrolysis furnace. The heating temperature of the electric heating jacket is detected by the thermocouple to assist the probe inside the furnace in precise temperature control.

[0036] A probe rod extending into the rotary pyrolysis furnace is fixedly inserted through the unidirectional air outlet. A temperature sensor 12 is installed at the end of the probe rod that extends into the rotary pyrolysis furnace, and the temperature sensor is used to accurately detect the temperature inside the furnace. In this embodiment, the length of the probe rod is 1 / 2 of the length of the rotary pyrolysis furnace body, so that the temperature sensor is located in the middle of the length direction of the rotary pyrolysis furnace, which is conducive to achieving better precise temperature control.

[0037] The non-contact, one-way sealed flue gas collection system includes an extraction pipe 4 and an exhaust fan 8 installed on the extraction pipe. The extraction pipe 4 can be a corrugated pipe for easy adjustment of the inlet angle. The inlet of the extraction pipe is located diagonally above the one-way outlet, along the flue gas flow direction, on the side of the one-way outlet away from the rotary pyrolysis furnace. In this embodiment, the one-way outlet and the inlet of the extraction pipe are located on the same vertical plane. A gas-solid separation zone is formed between the inlet of the extraction pipe and the one-way outlet. Under the action of the exhaust fan 8, the flue gas discharged from the rotary pyrolysis furnace 1 and the air in the gas-solid separation zone enter the extraction pipe 4. The air is used to cool the flue gas discharged from the rotary pyrolysis furnace, and large dust particles carried in the flue gas fall off in the gas-solid separation zone.

[0038] The non-contact unidirectional sealed flue gas collection system of this embodiment utilizes the positive pressure formed by the water vapor and flue gas generated by pyrolysis to achieve a unidirectional sealing effect, and uses a non-contact exhaust pipe to collect the flue gas and fresh air ejected from the furnace, thereby achieving the purpose of continuous collection of pyrolysis products.

[0039] In this embodiment, the axis of the unidirectional exhaust port 3 coincides with the rotation axis of the rotary pyrolysis furnace. The unidirectional exhaust port is located at the center point of rotation of the rotary pyrolysis furnace, and its diameter is 7cm~14cm to ensure that an effective positive pressure can be formed inside the furnace. The unidirectional exhaust port extends 10cm~15cm beyond the rotary pyrolysis furnace to prevent external air from entering the furnace due to gas vortices generated by the furnace rotation. The distance between the air inlet of the extraction pipe and the unidirectional exhaust port is 15cm~20cm, so that large dust particles ejected from the unidirectional exhaust port fall off before entering the extraction pipe. Simultaneously, air from the surrounding environment is drawn in during extraction to prevent negative pressure from being created inside the furnace by suction. The diameter of the air inlet of the extraction pipe is 18cm~20cm to ensure that sufficient fresh air and flue gas enter the extraction pipe simultaneously, using air to cool the high-temperature flue gas.

[0040] A dust collector 5 is also installed on the exhaust duct, and along the airflow direction, the dust collector 5 is located upstream of the exhaust fan 8. In this embodiment, the dust collector uses a cyclone dust collector, a common technology, to remove dust from the flue gas. The dust-removed flue gas then enters the smoke collection tower via the exhaust fan. The ratio of the cyclone diameter of the dust collector 5 to the inner diameter of the exhaust duct is 1.5:1. A dust collection tank 6 is installed at the bottom of the dust collector, and a rubber-sealed dust outlet 7 is provided at the lower end of the dust collection tank. Dust is collected through the dust collection tank, and the dust inside the dust collection tank can be cleaned through the dust outlet.

[0041] The smoke collection tower 9 is located on the outlet side of the extraction pipe. The inlet of the smoke collection tower is connected to the outlet of the extraction pipe. The smoke collection tower 9 contains a water storage tank, two layers of packing material, and a water spray system. The bottom of the smoke collection tower is connected to the filtration system through a drain pipe. An exhaust port is provided at the top of the smoke collection tower, and a gas detection probe 10 is installed at the exhaust port. An inspection port 11 is provided on the lower side of the smoke collection tower for convenient maintenance of the tower.

[0042] The water spray system comprises three spray layers, each equipped with several spiral nozzles distributed circumferentially. A water pump sprays purified water from a storage tank through these nozzles to scrub the flue gas, dissolving soluble substances. This process collects soluble substances from the flue gas through scrubbing. Insoluble substances and water vapor are discharged through a top outlet, where a gas detection probe 10 detects the presence of harmful gases. The filtration system utilizes existing technology, including a water pump 16, filter rods 15, and a liquid outlet valve 19. The water pump is electrically connected to a controller for easy operation. The pump pumps liquid to the filter rods, which then filter the collected flue gas solution. The filter rods, also existing technology, consist of a housing and a filter element within the housing. Liquid entering the housing passes through the filter element and exits through the housing's outlet. The water filtration system is connected to a storage tank; filtered water is pumped back to the storage tank via a transfer pump, enabling water recycling.

[0043] This embodiment also includes a control system 14, which is controlled by a PLC to regulate the furnace rotation speed, temperature, pyrolysis time, and the start-up timing of the flue gas collection tower water pump during the pyrolysis stage. When the furnace temperature is lower than the set value, the electric heating jacket is controlled to increase the heating temperature; when the furnace temperature is higher than the set value, the electric heating jacket is controlled to decrease the heating temperature.

[0044] This embodiment also provides a method for using a biomass low-temperature pyrolysis system based on positive pressure flue gas exhaust, including the following steps:

[0045] a. Load the biomass into the rotary pyrolysis furnace and close the sealed feed inlet;

[0046] b. The rotary pyrolysis furnace body rotates at 5-10 r / min. At the same time, the heating device heats the rotary pyrolysis furnace. When the temperature inside the furnace reaches 100℃, the biomass produces water vapor, which creates positive pressure inside the furnace. The water vapor displaces the air inside the furnace, creating an oxygen-deficient micro-positive pressure environment inside the furnace, preventing outside air from entering the furnace.

[0047] c. When the furnace temperature reaches 160-180℃, pyrolysis begins, and the flue gas generated by pyrolysis is discharged through the one-way outlet. At this time, the exhaust fan is turned on. Under the action of pressure difference, the flue gas discharged through the one-way outlet and the air in the gas-solid separation zone enter the exhaust pipe, preventing outside air from entering the rotary pyrolysis furnace through the one-way inlet. The gas-solid separation zone is used to make large dust particles carried in the flue gas fall off before entering the exhaust pipe.

[0048] d. The flue gas is cooled by the air entering the extraction pipe. After being cooled, the flue gas enters the smoke collection tower after being dusted by the dust collector. The flue gas is washed by the water spray system installed in the smoke collection tower. Insoluble gases and water vapor are discharged from the top of the smoke collection tower. The water after washing the flue gas is discharged from the bottom of the smoke collection tower and enters the filtration system for filtration.

[0049] e. After pyrolysis is complete, turn off the exhaust fan, open the sealing plug of the water inlet of the furnace door, and spray water into the rotary pyrolysis furnace through the water inlet to reduce the temperature inside the furnace.

[0050] This embodiment utilizes a self-generated positive pressure within the rotary pyrolysis furnace and a non-contact gas collection system to prevent oxygen backflow that could lead to spontaneous combustion. A cyclone dust collector is used to remove dust from the flue gas, and tar is cooled and separated in the gas collection pipeline, reducing the dust and tar content in the leached flue gas solution. This embodiment effectively solves the problem of product spontaneous combustion caused by oxygen infiltration during low-temperature biomass pyrolysis, while the suction effect of the exhaust fan improves the efficiency of heat recovery. The non-contact flue gas collection system has a simple structure and low cost. It utilizes external fresh air for cooling, converting high-temperature flue gas into ambient temperature gas for collection, reducing the operating cost of the spray system. Furthermore, this embodiment solves the problems of unidirectional sealing and temperature measurement in the equipment, while also offering high structural safety and low equipment cost.

[0051] Taking straw pyrolysis as an example, the usage method in this embodiment is as follows:

[0052] 1. Loading and sealing: Load the straw into the furnace body through the feed inlet 23, close the furnace door and press and seal it with graphite packing;

[0053] 2. Pyrolysis stage: The furnace rotates at 5-10 r / min, with a pyrolysis temperature range of 180-250℃. When the furnace temperature reaches 100℃, the straw produces water vapor, creating positive pressure inside the furnace. Air inside the furnace is expelled by the water vapor, thus forming an oxygen-deficient, slightly positive pressure environment inside the furnace. When the furnace temperature reaches 160-180℃, pyrolysis begins, and the pyrolysis gas is discharged through the one-way outlet 3. At this time, the exhaust fan is turned on to start collecting the pyrolysis flue gas.

[0054] 3. Product collection: The exhaust fan 8 draws in the gas. The flue gas is first mixed with the air through the exhaust pipe and then cooled. Then, it passes through the cyclone dust collector to remove more than 90% of the particulate matter. Then, it enters the smoke collection tower to wash and collect the flue gas. Insoluble gases and water vapor are discharged from the top of the tower.

[0055] 4. Cooling stage: After pyrolysis, turn off the exhaust fan, open the sealing plug of the water inlet of the furnace door, and spray water into the furnace through the water inlet at a flow rate of 10L / min. Within 15 minutes, the furnace temperature will drop to below 120℃.

[0056] Of course, the above description is not limited to the examples above. Technical features of this utility model not described can be implemented by or using existing technology, and will not be repeated here. The above embodiments and drawings are only used to illustrate the technical solution of this utility model and are not intended to limit this utility model. This utility model has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this utility model do not depart from the spirit of this utility model and should also fall within the protection scope of the claims of this utility model.

Claims

1. A biomass low-temperature pyrolysis system based on positive pressure flue gas exhaust, characterized in that: It includes a non-contact one-way sealed flue gas collection system and a rotary pyrolysis furnace (1) equipped with a heating device. One end of the rotary pyrolysis furnace (1) is provided with a sealed feed port (23), and the other end of the rotary pyrolysis furnace (1) is provided with a one-way gas outlet (3). The non-contact one-way sealed flue gas collection system includes an exhaust pipe (4) and an exhaust fan (8) installed on the exhaust pipe. The air inlet of the exhaust pipe is located obliquely above the one-way air outlet. Along the flue gas flow direction, the air inlet of the exhaust pipe is located on the side of the one-way air outlet away from the rotary pyrolysis furnace. A gas-solid separation zone is formed between the air inlet of the exhaust pipe and the one-way air outlet.

2. The biomass low-temperature pyrolysis system based on positive pressure flue gas exhaust according to claim 1, characterized in that: The sealed feed inlet (23) includes a furnace door (21) that is detachably fixed to the rotary pyrolysis furnace, and a graphite packing (20) disposed between the furnace door (21) and the rotary pyrolysis furnace.

3. The biomass low-temperature pyrolysis system based on positive pressure flue gas exhaust according to claim 2, characterized in that: The furnace door is provided with a water inlet (17), and a sealing plug is detachably installed inside the water inlet (17).

4. The biomass low-temperature pyrolysis system based on positive pressure flue gas exhaust according to claim 1, characterized in that: A dust collector (5) is also installed on the exhaust pipe, and along the airflow direction, the dust collector (5) is located upstream of the exhaust fan (8).

5. A biomass low-temperature pyrolysis system based on positive pressure flue gas exhaust according to claim 1, characterized in that: The axis of the unidirectional gas outlet coincides with the rotation axis of the rotary pyrolysis furnace, and the unidirectional gas outlet extends 10cm to 15cm beyond the rotary pyrolysis furnace.

6. The biomass low-temperature pyrolysis system based on positive pressure flue gas exhaust according to claim 1, characterized in that: The distance between the air inlet of the air extraction pipe and the one-way air outlet is 15cm to 20cm.

7. A biomass low-temperature pyrolysis system based on positive pressure flue gas exhaust according to claim 1, characterized in that: The heating device includes an insulating shell (18) that covers the rotary pyrolysis furnace circumferentially, and an electric heating jacket (2) disposed inside the insulating shell. A thermocouple (13) is disposed between the electric heating jacket (2) and the furnace wall of the rotary pyrolysis furnace.

8. A biomass low-temperature pyrolysis system based on positive pressure flue gas exhaust according to claim 1, characterized in that: A probe extending into the rotary pyrolysis furnace is inserted through the one-way gas outlet, and a temperature sensor (12) is installed at one end of the probe extending into the rotary pyrolysis furnace.

9. A biomass low-temperature pyrolysis system based on positive pressure flue gas exhaust according to claim 1, characterized in that: The exhaust port of the exhaust pipe is connected to a smoke collection tower (9), which is equipped with a water spray system. The bottom of the smoke collection tower is connected to a filter system through a drain pipe. An exhaust hole is opened at the top of the smoke collection tower, and a gas detection probe (10) is installed at the exhaust hole.

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