Biomass efficient pyrolysis-gasification method and integrated device

Abstract

The invention belongs to the field of biomass efficient pyrolysis / gasification, and particularly relates to a biomass efficient pyrolysis-gasification integrated device and method. The device comprises a pyrolyzing furnace body, wherein a first fuel gas high-temperature / flue gas inlet and a second fuel gas / high-temperature flue gas inlet are respectively formed in two sides of the lower part of the pyrolyzing furnace body; an inverted-hopper-shaped biomass inlet is formed in the upper portion of the pyrolyzing furnace body, a biomass pyrolytic carbon outlet is formed in the lower portion of the pyrolyzing furnace body, and the inverted-hopper-shaped biomass inlet is communicated with the biomass pyrolytic carbon outlet; a first flue gas outlet and a second flue gas outlet are respectively formed in two sides of the upper end of the pyrolyzing furnace body; the furnace wall of the pyrolyzing furnace is sequentially provided with a refractory outer wall face, a porous medium structure and a reduction-gradual expansion heat exchange wall face from outside to inside. The gas combustion process and the biomass pyrolysis process are mutually independent and do not influence each other, and the influence of smoke generated in the gas combustion process on the biomass pyrolysis process is effectively avoided.

Description

Technical Field

[0001] This invention belongs to the field of efficient biomass pyrolysis / gasification, specifically relating to an integrated device and method for efficient biomass pyrolysis-gasification, which is a device that can perform anaerobic pyrolysis or carbon dioxide gasification on biomass respectively. Background Technology

[0002] Biomass energy is not only a renewable energy source but also a carbon-neutral one. With fossil fuels facing depletion and the need to address global warming, biomass energy, due to its renewable and clean characteristics, is seeing a gradual increase in its utilization. Biomass is a vast resource, ranking as the fourth largest energy source after coal, oil, and natural gas. However, biomass energy, derived from plant photosynthesis, suffers from significant drawbacks, including high dispersion and low energy density. This low energy density severely impacts the energy utilization of biomass resources.

[0003] Currently, typical biomass treatment methods include combustion, gasification, and pyrolysis. Pyrolysis involves the thermochemical transformation of biomass under anaerobic or low-oxygen conditions. Pyrolysis can convert low-energy-density biomass feedstocks into high-energy-density biomass pyrolysis gas, biomass oil, and biochar. Gasification, on the other hand, involves the gasification of biomass into biomass gas under high-temperature conditions with the presence of carbon dioxide. Whether it's pyrolysis or gasification, continuously improving thermal efficiency is a major research direction in the thermochemical treatment of biomass, as insufficient thermal efficiency often leads to a waste of thermal energy resources.

[0004] Therefore, in order to improve the thermal utilization efficiency of the pyrolysis device and realize the multi-purpose use of the pyrolysis device, this invention proposes an integrated device for efficient biomass pyrolysis and gasification. Summary of the Invention

[0005] In view of the shortcomings mentioned in the background of the invention above, the present invention proposes a biomass high-efficiency pyrolysis / gasification device and method.

[0006] The technical solution of this invention:

[0007] An integrated device for efficient biomass pyrolysis-gasification includes a pyrolysis furnace body. A first high-temperature gas or flue gas inlet 1 and a second high-temperature gas or flue gas inlet 2 are respectively provided on both sides of the lower part of the pyrolysis furnace body. An inverted bucket-shaped biomass inlet 7 is provided on the upper part of the pyrolysis furnace body, and a biomass pyrolysis char outlet 3 is provided on the lower part of the pyrolysis furnace body. The inverted bucket-shaped biomass inlet 7 is connected to the biomass pyrolysis char outlet 3. A first flue gas outlet 5 and a second flue gas outlet 6 are respectively provided on both sides of the upper end of the pyrolysis furnace body. The furnace wall of the pyrolysis furnace consists of a refractory outer wall surface 9, a porous media structure layer 4, and a shrinking-expanding heat exchange wall surface from the outside to the inside.

[0008] Furthermore, the thickness of the porous dielectric structure layer 4 is 8-10 cm.

[0009] Furthermore, the porous media structure is filled with alumina microspheres with a diameter of 8 mm or with silicon carbide foam ceramic filler with a porosity of 0.4 or 10 ppm.

[0010] Furthermore, the diameters of the upper and lower chambers of the pyrolysis furnace are smaller than the diameter of the middle chamber.

[0011] Furthermore, the pyrolysis furnace body is cylindrical.

[0012] Furthermore, baffles for isolating oxygen are respectively provided in the inverted bucket-shaped biomass inlet 7 and the biomass pyrolysis char outlet 3.

[0013] This invention also provides a method for efficient biomass pyrolysis-gasification, which utilizes the aforementioned integrated device for efficient biomass pyrolysis-gasification, and specifically includes the following steps:

[0014] (1) Biomass enters the biomass pyrolysis system through biomass inlet 7 and the biomass inlet and biochar outlet are closed to isolate air;

[0015] (2) High-temperature flue gas enters the heating system through the first gas high-temperature / flue gas inlet 1 and the second gas / high-temperature flue gas inlet 2; the flue gas pressure is not higher than 5 kPa and the flow velocity is not higher than 2 m / s.

[0016] (3) In the heating system, high-temperature flue gas and porous media structure 4 and shrink-expansion heat exchange wall 8 exchange heat, while the porous media also exchange heat through heat conduction and between the wall.

[0017] (4) While heat exchange occurs between the flue gas and the heating system, the porous medium and the wall surface exchange heat with the biomass pyrolysis system, thereby heating the biomass in the pyrolysis system and causing it to pyrolyze.

[0018] (5) During the process from the inlet to the outlet, the flue gas undergoes sufficient heat exchange with the porous medium and then flows out from the first flue gas outlet 5 and the second flue gas outlet 6.

[0019] Furthermore, the pyrolysis time in step (4) is 30 min to 120 min.

[0020] Furthermore, steps (2) and (3) can be replaced as follows: Step (2) is that the blast furnace gas is first premixed with air and then enters the heating system through the first gas high temperature / flue gas inlet 1 and the second gas / high temperature flue gas inlet 2 and is ignited in the porous medium area;

[0021] Step (3) is the process in which the blast furnace gas is burned in the porous medium area. The high temperature flue gas exchanges heat with the porous medium structure 4 and the shrinking-expanding heat exchange wall 8, while the porous medium also exchanges heat with the wall through heat conduction.

[0022] In this invention: (1) The pyrolysis device is mainly divided into two systems: a biomass pyrolysis system and a heat supply-storage system. The pyrolysis system can either add baffles at the inlet and outlet to isolate oxygen to achieve anaerobic pyrolysis or absorb carbon dioxide to gasify the biomass. (2) The heat supply-storage system adopts a porous media structure. The porous media is generally filled with alumina spheres with a diameter of 8 mm or silicon carbide foam ceramics with a porosity of 10 ppm. On the one hand, it makes full use of the heat storage capacity of the porous media; on the other hand, it adopts a porous media combustion structure to achieve efficient and low-NOx combustion of the fuel gas.

[0023] The heating-storage system can either directly burn fuel gas through porous media for heating, or utilize industrial waste heat, such as high-temperature flue gas waste heat, by directly introducing high-temperature flue gas into the porous media system to facilitate heat exchange between the flue gas and the porous media. Furthermore, the high-temperature flue gas generated during combustion also participates in heat transfer between the porous media. The formula for calculating the flow resistance experienced by the flue gas when passing through the porous ceramic is as follows:

[0024]

[0025] In the formula: μ refers to the dynamic viscosity of flue gas / Pa·s, 1 / α refers to the viscous resistance coefficient of flue gas flowing between porous ceramics, and C2 represents the inertial resistance coefficient of flue gas flow.

[0026] The heat transfer calculation between high-temperature flue gas and porous media is as follows:

[0027]

[0028] Nu = 2.0 + 1.1 Re 0.6 Pr 1 / 3

[0029]

[0030] In the formula; h v The convective heat transfer coefficient between the gas and solid phases is expressed as W·m. 2 d represents the diameter of the porous medium sphere in meters (m), Re represents the Reynolds number of the gas flow, and Pr represents the Prandtl number. p The isobaric heat capacity of a gas is expressed in kJ·kg. -1 ·℃ -1 , λ g The thermal conductivity of a gas is expressed in W·m. 2 .

[0031] The heat transfer between the gas and solid phases is:

[0032] Q = h v A(T g -T s )τ

[0033] In the formula, A represents the area of ​​the heat transfer surface between the gas and solid phases (m²). 2 T g Indicates gas temperature in K, T s τ represents the solid temperature in K, and τ represents the heat transfer time in seconds.

[0034] The heat transfer calculations within the porous media reveal two key advantages: First, the porous media introduces additional resistance to the high-temperature flue gas, slowing its flow and increasing the heat transfer time between the gas and solid phases. Second, the large specific surface area of ​​the porous media significantly increases the heat transfer area between the gas and solid phases, further facilitating heat transfer. Once the porous media stores heat, it transfers this heat to the biomass for pyrolysis through conduction and convection. Therefore, using porous media as a heat storage medium can improve the utilization efficiency of waste heat from the flue gas during pyrolysis.

[0035] (3) The combustion process of the gas and the pyrolysis process of the biomass are independent of each other and do not affect each other. This effectively avoids the influence of the flue gas generated during the combustion process on the pyrolysis process of the biomass.

[0036] (4) The porous medium heat transfer-storage system exchanges heat through the wall and the biomass pyrolysis system, thereby pyrolyzing the biomass.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] (1) The pyrolysis system and the heating system are independent of each other and do not affect each other;

[0039] (2) Using carbon dioxide as a biomass gasification agent to replace air or pure oxygen improves the safety of the biomass gasification process and promotes the resource utilization of carbon dioxide.

[0040] (3) The heating system can both burn gas for heating and fully recover and utilize industrial waste heat for biomass pyrolysis.

[0041] (4) The use of a porous medium structure in the heating system is beneficial to enhance heat exchange between the heating system and the pyrolysis system and improve thermal efficiency.

[0042] (5) This pyrolysis device can realize both anaerobic pyrolysis and oxygenation of biomass.

[0043] (6) Using a Venturi-type shrinking and expanding heat exchange wall can increase the heat exchange area, which is beneficial to enhance the heat exchange between flue gas and porous media, flue gas and wall, and heat exchange wall and pyrolysis system. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structure of the present invention.

[0045] In the diagram: 1-First gas / high-temperature flue gas inlet, 2-Second gas / high-temperature flue gas inlet, 3-Biomass pyrolysis char outlet, 4-Porous media structure layer, 5-First flue gas outlet, 6-Second flue gas outlet, 7-Biomass inlet, 8-Reducing-expanding heat exchange wall, 9-Refractory wall, 10-Pyrolysis furnace chamber. Detailed Implementation

[0046] The invention will now be further described with reference to the accompanying drawings.

[0047] like Figure 1 The diagram shows a high-efficiency biomass pyrolysis device.

[0048] An integrated device for efficient biomass pyrolysis and gasification includes a pyrolysis furnace body. A first high-temperature gas or flue gas inlet 1 and a second high-temperature gas or flue gas inlet 2 are respectively located on both sides of the lower part of the furnace body. An inverted bucket-shaped biomass inlet 7 is located above the furnace body, and a biomass pyrolysis char outlet 3 is located below the furnace body. The inverted bucket-shaped biomass inlet 7 is connected to the biomass pyrolysis char outlet 3. A first flue gas outlet 5 and a second flue gas outlet 6 are respectively located on both sides of the upper end of the furnace body. The furnace wall, from the outside to the inside, consists of a refractory outer wall surface 9, a porous media structure 4, and a shrinking-expanding heat exchange wall surface. The porous media structure is filled with alumina microspheres with a diameter of 8 mm or silicon carbide foam ceramic filler with a porosity of 10 ppm. The diameter of the upper and lower chambers of the furnace is smaller than the diameter of the middle chamber. The furnace body is cylindrical. Baffles for isolating oxygen can be respectively installed in the inverted bucket-shaped biomass inlet 7 and the biomass pyrolysis char outlet 3. Specific Implementation Example 1

[0050] This embodiment illustrates the process of biomass pyrolysis by recovering waste heat from high-temperature flue gas (around 500°C) generated during industrial processes. The specific steps are as follows:

[0051] (1) Biomass with a processing capacity of 100 kg / h (usually depending on the field test and equipment) enters the biomass pyrolysis system through biomass inlet 7 and the biomass inlet and biochar outlet are closed to isolate it from contact with the outside air.

[0052] (2) High-temperature flue gas enters the heating system through the first high-temperature flue gas inlet 1 and the second high-temperature flue gas inlet 2. The flue gas pressure is not higher than 5 kPa and the flow velocity is not higher than 2 m / s.

[0053] (3) In the heating system, high-temperature flue gas and porous medium 4 and heat exchange wall 8 exchange heat, while the porous medium also exchanges heat with the wall through heat conduction.

[0054] (4) While heat exchange occurs between the flue gas and the heating system, the porous medium and the wall surface exchange heat with the biomass pyrolysis system, thereby heating the biomass in the pyrolysis system and causing it to pyrolyze. The pyrolysis time is generally 30-120 minutes. Field experience shows that one hour is generally more reasonable.

[0055] (5) As the flue gas is filled with a large amount of porous media during the process from the inlet to the outlet, the flue gas flows out from the outlet after sufficient heat exchange with the porous media.

[0056] (6) The purpose of using a gradually narrowing and expanding wall surface is to increase the heat exchange area and improve the flow conditions of flue gas in porous media.

[0057] (7) After a period of time, the biomass in the pyrolysis system is gradually heated and pyrolyzed. Specific Implementation Example 2

[0059] In this embodiment, biomass pyrolysis is illustrated by burning blast furnace gas to generate heat (the porous media burner is indicated by reference numerals 1 and 2 in the attached figure, but a direct high-temperature flue gas inlet can also be used).

[0060] The specific steps are as follows:

[0061] (1) A certain amount of biomass enters the biomass pyrolysis system through the biomass inlet 7 and the biomass inlet and biochar outlet are closed to isolate it from contact with the outside air.

[0062] (2) The blast furnace gas is first premixed with air and then enters the heating system through the first gas high temperature / flue gas inlet 1 and the second gas / high temperature flue gas inlet 2 and is ignited in the porous medium area.

[0063] During the combustion of the blast furnace gas in the porous medium region, the heat generated by combustion is rapidly exchanged with the porous medium, and the heat is also quickly heated by the wall to heat the biomass in the pyrolysis system.

[0064] (3) During the combustion of blast furnace gas in the porous medium region, the high-temperature flue gas exchanges heat with the porous medium 4 and the heat exchange wall 8, while the porous medium also exchanges heat with the wall through heat conduction.

[0065] (4) While heat exchange occurs between the flue gas and the heating system, the porous medium and the wall surface exchange heat with the biomass pyrolysis system, thereby heating the biomass in the pyrolysis system and causing it to pyrolyze.

[0066] (5) As the flue gas is filled with a large amount of porous media during the process from the inlet to the outlet, the flue gas flows out from the outlet after sufficient heat exchange with the porous media. The porous media fully absorbs the heat of the flue gas.

[0067] (6) The purpose of using a gradually narrowing and expanding wall surface is to increase the heat exchange area and improve the flow conditions of flue gas in porous media.

[0068] (7) After a period of time, the biomass in the pyrolysis system is gradually heated and pyrolyzed. Specific Implementation Example 3

[0070] This embodiment illustrates the process of biomass carbon dioxide gasification through the combustion of blast furnace gas. This method promotes the application of carbon dioxide and broadens the pathways for biomass gasification. The specific steps are as follows:

[0071] (1) A certain amount of biomass enters the biomass pyrolysis system through the biomass inlet 7. The biomass inlet and the biomass char outlet are always connected. During the biomass pyrolysis process, the bottom gasification method can also be adopted to draw the biomass gasification gas out from the bottom of the device, thereby reducing the tar content in the gasification gas.

[0072] (2) The blast furnace gas is first premixed with air and then enters the heating system through the first gas high temperature / flue gas inlet 1 and the second gas / high temperature flue gas inlet 2 and is ignited in the porous medium area.

[0073] During the combustion of blast furnace gas in the porous medium region, the heat generated by combustion rapidly exchanges heat with the porous medium, and the heat is also quickly heated by the walls of the biomass in the pyrolysis system. Simultaneously, due to the use of a downdraft method for biomass gasification, when the biomass gasified gas passes through the region of intense blast furnace gas combustion, the high combustion temperature results in a correspondingly high temperature within the pyrolysis region. As the gasified gas passes through this high-temperature region, the tar in the gasified gas undergoes further pyrolysis.

[0074] (3) During the combustion of blast furnace gas in the porous medium region, the high-temperature flue gas exchanges heat with the porous medium 4 and the heat exchange wall 8, while the porous medium also exchanges heat with the wall through heat conduction.

[0075] (4) While heat exchange occurs between the flue gas and the heating system, the porous medium and the wall surface exchange heat with the biomass pyrolysis system, thereby heating the biomass in the pyrolysis system and causing it to pyrolyze.

[0076] (5) As the flue gas is filled with a large amount of porous media during the process from the inlet to the outlet, the flue gas flows out from the outlet after sufficient heat exchange with the porous media. The porous media fully absorbs the heat of the flue gas.

[0077] (6) The purpose of using a gradually narrowing and expanding wall surface is to increase the heat exchange area and improve the flow conditions of flue gas in porous media.

[0078] (7) After a period of time, the biomass in the pyrolysis system is gradually heated and pyrolyzed and gasified.

[0079] (8) Since carbon dioxide is used as the gasifying agent for biomass pyrolysis, there is no need to worry about the gasified gas burning under high temperature conditions during the pyrolysis gasification process, which could lead to dangerous hazards.

[0080] Furthermore, during the biomass gasification process, carbon dioxide reacts with the carbon in the biomass under high-temperature conditions to produce carbon monoxide. Additionally, carbon dioxide may react with hydrogen to produce methane. This process is beneficial for both promoting the pyrolysis and gasification of biomass and for the resource utilization of carbon dioxide.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principle of the present invention are included within the scope of protection of the present invention.

Claims

1. An integrated device for high-efficiency biomass pyrolysis-gasification, comprising a pyrolysis furnace body, characterized in that, A first high-temperature gas / flue gas inlet (1) and a second high-temperature gas / flue gas inlet (2) are respectively provided on both sides of the lower part of the pyrolysis furnace body; an inverted bucket-shaped biomass inlet (7) is provided on the upper part of the pyrolysis furnace body, and a biomass pyrolysis char outlet (3) is provided on the lower part of the pyrolysis furnace body, and the inverted bucket-shaped biomass inlet (7) is connected to the biomass pyrolysis char outlet (3); a first flue gas outlet (5) and a second flue gas outlet (6) are respectively provided on both sides of the upper end of the pyrolysis furnace body; the furnace wall of the pyrolysis furnace consists of a refractory outer wall surface (9), a porous media structure layer (4), and a shrinking-expanding heat exchange wall surface (8) from the outside to the inside.

2. The integrated device for high-efficiency biomass pyrolysis-gasification according to claim 1, characterized in that, Baffles for isolating oxygen are respectively provided in the inverted bucket-shaped biomass inlet (7) and the biomass pyrolysis char outlet (3).

3. The integrated device for high-efficiency biomass pyrolysis-gasification according to claim 1, characterized in that, The diameters of the upper and lower chambers of the pyrolysis furnace are smaller than the diameter of the middle chamber.

4. The integrated device for high-efficiency biomass pyrolysis-gasification according to claim 1, characterized in that, The porous media structure is filled with alumina microspheres with a diameter of 8 mm or with silicon carbide foam ceramics with a porosity of 0.4 or 10 ppm.

5. A highly efficient biomass pyrolysis-gasification method, characterized in that, The integrated biomass high-efficiency pyrolysis-gasification device described in any one of claims 1-4 specifically includes the following steps: (1) Biomass enters the biomass pyrolysis system through the biomass inlet (7) and the biomass inlet and biochar outlet are closed to isolate the air; (2) High-temperature flue gas enters the heating system through the first gas high-temperature / flue gas inlet (1) and the second gas / high-temperature flue gas inlet (2); the flue gas pressure is not higher than 5 kPa and the flow velocity is not higher than 2 m / s; (3) Heat exchange occurs between high-temperature flue gas and porous media structure (4) and shrinking-expanding heat exchange wall (8) in the heating system, while the porous media also exchange heat through heat conduction and between the wall. (4) While heat exchange occurs between the flue gas and the heating system, the porous medium and the wall surface exchange heat with the biomass pyrolysis system, thereby heating the biomass in the pyrolysis system and causing it to pyrolyze. (5) During the process of flue gas from the inlet to the outlet, after sufficient heat exchange with the porous medium, it flows out from the first flue gas outlet (5) and the second flue gas outlet (6).

6. The efficient biomass pyrolysis-gasification method according to claim 5, characterized in that, The pyrolysis time in step (4) is 30 min to 120 min.

7. The efficient biomass pyrolysis-gasification method according to claim 5, characterized in that, The step (2) involves the blast furnace gas being premixed with air and then entering the heating system through the first high-temperature gas / flue gas inlet (1) and the second high-temperature gas / flue gas inlet (2), where it is ignited in the porous medium area. Step (3) is the process of blast furnace gas burning in the porous medium area, where high-temperature flue gas exchanges heat with the porous medium structure (4) and the shrinking-expanding heat exchange wall (8), and the porous medium also exchanges heat with the wall through heat conduction.

8. The efficient biomass pyrolysis-gasification method according to claim 5, characterized in that, The formula for calculating the flow resistance experienced by flue gas when passing through porous ceramic is as follows: In the formula: μ refers to the dynamic viscosity of flue gas / Pa·s, 1 / α refers to the viscous resistance coefficient of flue gas flowing between porous ceramics, and C2 represents the inertial resistance coefficient of flue gas flow.

9. The efficient biomass pyrolysis-gasification method according to claim 5, characterized in that, The heat transfer calculation between high-temperature flue gas and porous media is as follows: Now=2.0+1.1Re 0.6 Per 1 / 3 In the formula; h v The convective heat transfer coefficient between the gas and solid phases is expressed as W·m. 2 d represents the diameter of the porous medium sphere in meters (m), Re represents the Reynolds number of the gas flow, and Pr represents the Prandtl number. p The isobaric heat capacity of a gas is expressed in kJ·kg. -1 ·℃ -1 , λ g The thermal conductivity of a gas is expressed in W·m. 2 .

10. The efficient biomass pyrolysis-gasification method according to claim 5, characterized in that, The heat transfer between the gas and solid phases is: Q=h v A(T g -T s )τ In the formula, A represents the area of ​​the heat transfer surface between the gas and solid phases (m²). 2 T g Indicates gas temperature in K, T s τ represents the solid temperature in K, and τ represents the heat transfer time in seconds.

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