Biomass chemical chain gasification device and method

Abstract

The invention discloses a biomass chemical chain gasification device which comprises an oxidation reactor, an oxygen release reactor and a gasification reactor, the oxidation reactor is connected with a first cyclone separator, a lower outlet of the first cyclone separator is connected with a first material returning vertical pipe, the first material returning vertical pipe is connected with a first material returning valve, and the first material returning valve is connected with a second material returning valve. The first material returning valve is connected with the oxygen release reactor, the oxygen release reactor is connected with a second cyclone separator, an outlet in the lower portion of the second cyclone separator is connected with a second material returning vertical pipe, the second material returning vertical pipe is connected with a second material returning valve, the second material returning valve is connected with the gasification reactor, and the top of the second cyclone separator is connected with an airflow pipeline. A traditional single gasification reactor is decoupled into an oxygen release reactor and a gasification reactor, and the oxygen release reactor and the gasification reactor are integrated into a whole. Zoned control of oxygen carrier reduction and biomass gasification is realized, and negative effects of a complex reaction system on gasification efficiency are effectively avoided. And the reaction process is more ordered, so that the overall gasification efficiency is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass gasification, and particularly relates to a biomass chemical looping gasification device and method. Background Art

[0002] Biomass gasification is widely used in the production of syngas. Biomass is converted into syngas through the action of high temperature and gasifying agents. By-products such as tar and coke are generated during this process. Steam gasification and CO2 gasification can produce syngas with better quality, but both of these processes are strongly endothermic processes and require external heat sources to meet the self-heating operation of the system. Chemical looping technology is an innovative method for chemical conversion and energy utilization. This technology decomposes the traditional single chemical conversion process into two or more reaction steps, realizing the organic combination of reaction and separation. In the clean utilization of biomass, chemical looping technology shows great application prospects. Currently, there are research reports focusing on the application of chemical looping technology in biomass utilization. These studies mainly focus on the design of unit technology devices, the research and development of oxygen carriers, and the optimization and control of reaction conditions. Chemical looping gasification technology realizes the efficient gasification of biomass by means of an oxygen carrier transferring lattice oxygen, effectively avoiding the dilution of N2 during air gasification and the high oxygen production cost during oxygen gasification. At the same time, the oxygen carrier also serves as a heat carrier to maintain the heat balance between reactors, enabling the self-heating operation of the system without external heating.

[0003] In the gasification reactor, the oxygen carrier provides lattice oxygen for biomass to generate high-quality syngas, while being reduced itself. The reduced oxygen carrier is sent into the oxidation reactor and oxidized by air to return to its initial state. The oxidized oxygen carrier is then sent back into the gasification reactor to provide oxygen for the fuel. In this way, the chemical looping gasification of the fuel is realized through the circulation of the oxygen carrier in two reactors, and finally converted into syngas mainly composed of H2 and CO. However, its reaction system is complex and intertwined, resulting in some challenges in biomass chemical looping gasification. For example, problems such as the slow reaction rate of biomass gasification, the low conversion rate of biomass gasification to produce syngas, and the low selectivity of syngas. Summary of the Invention

[0004] The purpose of the present invention is to provide a biomass chemical looping gasification device and method to solve the above problems, so as to solve the problems of slow reaction rate of existing biomass gasification, low conversion rate of biomass gasification to produce syngas, and low selectivity of syngas.

[0005] To achieve the above object, the present invention provides the following technical solutions: A biomass chemical looping gasification device, comprising: an oxidation reactor, an oxygen release reactor, and a gasification reactor. The oxidation reactor is connected to a first cyclone separator. The lower outlet of the first cyclone separator is connected to a first return riser. The first return riser is connected to a first return valve. The first return valve is connected to the oxygen release reactor. The oxygen release reactor is connected to a second cyclone separator. The lower outlet of the second cyclone separator is connected to a second return riser. The second return riser is connected to a second return valve. The second return valve is connected to the gasification reactor. The top of the second cyclone separator is connected to an air flow pipeline.

[0006] As a further improvement of the above technical solution:

[0007] The air flow pipeline is connected to an air flow branch pipe, and the air flow branch pipe is connected to the gasification reactor through a recycle fan.

[0008] The oxidation reactor is an equal-diameter cylindrical structure.

[0009] The oxygen release reactor and the gasification reactor are of an integral structure. The oxygen release reactor is an equal-diameter cylindrical structure. The gasification reactor comprises a variable-diameter cone structure with a smaller upper part and a larger lower part and an equal-diameter cylindrical structure. The diameter of the oxygen release reactor is equal to the minimum diameter of the variable-diameter cone structure. The equal-diameter cylindrical structure of the gasification reactor is equal to the maximum diameter of the variable-diameter cone structure.

[0010] A first feed inlet is arranged on the lower side of the oxidation reactor, and the first feed inlet forms an angle of 45° - 60° with the horizontal direction.

[0011] A second feed inlet is arranged on the lower side of the gasification reactor, and the second feed inlet forms an angle of 45° - 60° with the horizontal direction.

[0012] A third feed inlet is arranged on the lower side of the oxygen release reactor, and the third feed inlet forms an angle of 45° - 60° with the horizontal direction.

[0013] The oxidation reactor and the oxygen release reactor are fast fluidized beds, the gasification reactor is a turbulent fluidized bed, and a fluidized bed gas-solid outlet is arranged at the junction of the variable diameter and the equal diameter of the gasification reactor and is connected to the feed inlet at the lower part of the oxidation reactor through a third return valve.

[0014] The present invention discloses a biomass chemical looping gasification method, comprising the following steps:

[0015] Biomass is pyrolyzed and gasified in the lower part of the gasification reactor to generate coke, syngas, tar, and light hydrocarbons. At the same time, under the catalytic action of the oxygen carrier, part of the tar, light hydrocarbons, and water react to generate syngas again;

[0016] The syngas enters the second cyclone separator after passing through the oxygen release reactor and is separated into the gas flow pipeline;

[0017] After the air from the oxidation reactor fluidizes and oxidizes the oxygen carrier material, the oxygen carrier flows to the oxygen release reactor through the first return valve. In the oxygen release reactor, the oxygen carrier conveys the oxygen carrier particles upward under the action of an air velocity of 6 - 10 m / s and releases gaseous oxygen.

[0018] The oxygen carrier after releasing oxygen enters the gasification reactor after being separated by the second cyclone separator, mixes with the biomass particles, and participates in the catalytic pyrolysis gasification reaction of the biomass. Subsequently, the oxygen carrier returns to the oxidation reactor through the third return valve;

[0019] Part of the gas in the gas flow pipeline returns to the gasification reactor from the gas flow branch through the recycle fan and is recycled again.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] Optimizing the reactor design and improving the gasification efficiency: In the traditional single gasification reactor, the reaction system is complex and various reactions are intertwined, resulting in low gasification efficiency. The present invention decouples the traditional single gasification reactor into an oxygen release reactor and a gasification reactor and integrates them into a whole. It realizes the zoning control of the oxygen carrier reduction and biomass gasification, effectively avoiding the negative impact of the complex reaction system on the gasification efficiency. In the oxygen release reactor, the oxygen carrier releases oxygen, creating conditions for the subsequent reaction with the syngas; in the gasification reactor, the biomass undergoes pyrolysis gasification reaction. The two reactors perform their respective functions, making the reaction process more orderly, thus significantly improving the overall gasification efficiency.

[0022] Realizing the fluidization zoning control and strengthening the reaction effect: Through precise control of the gas velocity, the fluidization zoning control is achieved. The oxidation reactor and the oxygen release reactor adopt the form of a fast fluidized bed, and the internal gas velocity can reach 6 - 10 m / s. This relatively high velocity enables the oxygen carrier to flow rapidly in the reactor, which is beneficial to the oxidation of the oxygen carrier and the release of oxygen; while the gasification reactor adopts the form of a turbulent fluidized bed, and the internal gas velocity is 0.5 - 1.2 m / s. The relatively low velocity ensures that the biomass has sufficient residence time in the reactor for pyrolysis gasification reaction, and is also beneficial to the full contact between the oxygen carrier and the biomass, strengthening the catalytic reaction effect. Different fluidization states cooperate in different regions, promoting the efficient progress of the entire chemical looping gasification process.

[0023] Adopting a catalytic oxygen carrier to improve biomass conversion rate and syngas quality: An oxygen-releasing carrier with catalytic function is adopted, which has multiple advantages. In the oxygen-releasing reactor, the oxygen carrier releases oxygen and undergoes a combustion reaction with part of the syngas, and the heat released can supply the energy required for biomass pyrolysis, reducing the need for external heating and achieving the self-heating operation of the system. After releasing oxygen, metal elements are exposed on the surface of the oxygen carrier. When it returns to the gasification reactor, these metal elements can catalyze the pyrolysis gasification reaction of biomass. Taking a copper-based oxygen carrier as an example, after it releases oxygen, the copper element can promote the decomposition of macromolecular organic substances in biomass, enabling biomass to be more fully converted into syngas, thus improving the biomass conversion rate. At the same time, the catalytic effect can also reduce the content of impurities such as tar and light hydrocarbons in the syngas, improving the quality of the syngas and making it more suitable for subsequent utilization. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0026] The description of the reference numerals in the drawings is as follows: 10, air flow pipeline; 11, air flow branch pipe; 12, recycle fan; 3, oxidation reactor; 41, first cyclone separator; 42, second cyclone separator; 51, first return leg; 52, second return leg; 61, first return valve; 62, second return valve; 63, third return valve; 71, first feed inlet; 72, second feed inlet; 73, third feed inlet; 8, gasification reactor; 9, oxygen-releasing reactor. Detailed Embodiments

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope protected by the present invention.

[0028] As Figure 1As shown in the figure, the biomass chemical-looping gasification device of this embodiment includes an oxidation reactor 3, an oxygen-release reactor 9, and a gasification reactor 8. The oxidation reactor 3 is connected to a first cyclone separator 41. The lower outlet of the first cyclone separator 41 is connected to a first return riser 51. The first return riser 51 is connected to a first return valve 61. The first return valve 61 is connected to the oxygen-release reactor 9. The oxygen-release reactor 9 is connected to a second cyclone separator 42. The lower outlet of the second cyclone separator 42 is connected to a second return riser 52. The second return riser 52 is connected to a second return valve 62. The second return valve 62 is connected to the gasification reactor 8. The top of the second cyclone separator 42 is connected to an air flow pipeline 10. Discharge pipes are arranged on the oxidation reactor 3 and the gasification reactor 8. Air distribution plates 2 and air chambers 1 are arranged at the lower parts of the oxidation reactor 3 and the gasification reactor 8;

[0029] The air flow pipeline 10 is connected to an air flow branch pipe 11, and the air flow branch pipe 11 is connected to the gasification reactor 8 through a recycle fan 12.

[0030] The oxidation reactor 3 has an equal-diameter cylinder structure.

[0031] The oxygen-release reactor 9 and the gasification reactor 8 are of an integral structure. The oxygen-release reactor 9 has an equal-diameter cylinder structure. The gasification reactor 8 includes a variable-diameter cone structure with a smaller upper part and a larger lower part and an equal-diameter cylinder structure. The diameter of the oxygen-release reactor 9 is equal to the minimum diameter of the variable-diameter cone structure. The equal-diameter cylinder structure of the gasification reactor 8 is equal to the maximum diameter of the variable-diameter cone structure. This is convenient for constructing a turbulent fluidization state. The variable-diameter cone is the transition section between the gasification reactor (with a large diameter) and the oxygen-release reactor (with a small diameter).

[0032] A first feed inlet 71 is arranged on the lower side of the oxidation reactor 3, and the first feed inlet 71 forms an angle of 45° - 60° with the horizontal direction.

[0033] A second feed inlet 72 is arranged on the lower side of the gasification reactor 8, and the second feed inlet 72 forms an angle of 45° - 60° with the horizontal direction.

[0034] A third feed inlet 73 is arranged on the lower side of the oxygen-release reactor 9, and the third feed inlet 73 forms an angle of 45° - 60° with the horizontal direction. Such an arrangement is convenient for the flow and descent of solid materials.

[0035] The oxidation reactor 3 and the oxygen-release reactor 9 are fast fluidized beds, and the gasification reactor 8 is a turbulent fluidized bed. A fluidized bed gas-solid outlet is arranged at the junction of the variable diameter and the equal diameter of the gasification reactor 8, and is connected to the feed inlet at the lower part of the oxidation reactor 3 through a third return valve 63.

[0036] When the biomass chemical looping gasification device is in operation, a sufficient amount of oxygen carrier particles is added into the oxidation reactor 3. The oxygen carrier particles are an oxygen-releasing metal oxide, including but not limited to materials such as copper-based, manganese-based, spinel, perovskite, etc.; the fluidization air volume in the oxidation reactor 3 is adjusted so that the oxygen carrier particles present a bubbling state. After the oxygen carrier particles carry oxygen, they enter the oxygen release reactor 9 through the side outlet of the oxidation reactor 3 via the first return valve 61. In the oxygen release reactor 9, by adjusting the fluidization air volume, the oxygen carrier flows upward and releases oxygen. The oxygen carrier that has released oxygen enters the gasification reactor 8 through the fluidized gas-solid separation outlet at the upper part of the oxygen release reactor 9 via the second return valve 62. A turbulent flow state exists in the gasification reactor 8, and the oxygen carrier particles can slowly flow back into the oxidation reactor 3 through the third return valve 63 in the upper middle part of the gasification reactor 8. After the operation is stable, the gasification reactor 8 is fluidized by steam and recycled flue gas, and biomass is added into the gasification reactor 8. Since the gas flow rate in the gasification reactor 8 is low, the biomass will not be carried to a high place. At the bottom of the gasification reactor 8, the biomass undergoes a pyrolysis reaction to generate coke, syngas, tar, and low-carbon hydrocarbons; some low-carbon hydrocarbons and coke will further react with water to generate syngas. At the same time, under the catalysis of the oxygen carrier that has released oxygen, some tar and low-carbon hydrocarbons can also react with water to generate syngas. The generated gas flows upward under the action of the gas flow into the oxygen release reactor 9. In the oxygen release reactor 9, part of the syngas reacts with a small amount of tar, low-carbon hydrocarbons, and oxygen to generate carbon dioxide and water and release energy, and this part of the energy is used to supply the endothermic reaction of biomass pyrolysis. Subsequently, the gas and the oxygen carrier enter the second cyclone separator 42, and after separation, the gas is introduced into the gas flow pipeline 10. A branch pipe 11 is led out from the gas flow pipeline 10 and connected to the recycle fan 12, and a part of the syngas, tar, low-carbon hydrocarbons, etc. are recycled back into the gasification reactor 8 for further conversion.

[0037] Through fluidization zone control, the present invention divides the traditional single gasification reactor into two parts, namely an oxygen release reactor and a gasification reactor, realizing the transfer and storage of the chemical energy in part of the syngas into the oxygen carrier through the combustion reaction of the syngas and the released gaseous oxygen, and then using this part of the chemical energy for the endothermic reaction of biomass gasification through the oxygen carrier cycle; by adopting an oxygen-releasing carrier with a catalytic function, the oxygen carrier not only releases oxygen to burn part of the syngas to release heat to supply the energy demand for biomass pyrolysis, but also the oxygen carrier that exposes metal elements after releasing oxygen returns to the gasification reactor to catalyze the pyrolysis gasification reaction of biomass, improving the conversion rate of biomass and the quality of syngas; by using the recycle fan to reintroduce a part of the reaction gas into the gasification reactor to participate in the reaction, the yield of syngas is further increased. The present invention provides a solution to solve the problems that the carbon conversion rate of biomass gasification is lower than 50% and the selectivity of syngas is lower than 60%.

[0038] The present invention provides a novel biomass gasification method to solve the problems of low conversion rate and low syngas selectivity in current chemical-looping biomass gasification, which includes the following steps:

[0039] After the air from the oxidation reactor 3 fluidizes and oxidizes the oxygen carrier material, the oxygen carrier flows through the first return valve 61 to the oxygen release reactor 9. In the oxygen release reactor 9, the oxygen carrier conveys the oxygen carrier particles upward under the action of a wind speed of 6 - 10 m / s and releases gaseous oxygen.

[0040] The oxygen carrier after releasing oxygen is separated by the second cyclone separator 42 and then enters the gasification reactor 8, where it is mixed with biomass particles and participates in the catalytic pyrolysis gasification reaction of biomass. Subsequently, the oxygen carrier returns to the oxidation reactor 3 again through the third return valve 63.

[0041] In the lower part of the gasification reactor 8, biomass pyrolysis gasification generates coke, syngas, tar, and light hydrocarbons. At the same time, under the catalytic action of the oxygen carrier, part of the tar, light hydrocarbons, and water react to generate syngas.

[0042] The syngas enters the second cyclone separator 42 after passing through the oxygen release reactor 9 and is separated into the gas flow pipeline 10.

[0043] Part of the gas in the gas flow pipeline 10 returns to the gasification reactor 8 from the gas flow branch pipe 11 through the recycle fan 12 for re - circulation.

[0044] Within the technical scope disclosed by the present invention, changes or substitutions that can be easily conceived should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A biomass chemical chain gasification device, characterized in that: include: An oxidation reactor (3), an oxygen release reactor (9) and a gasification reactor (8), wherein the oxidation reactor (3) is connected to a first cyclone separator (41), the lower outlet of the first cyclone separator (41) is connected to a first return material standpipe (51), the first return material standpipe (51) is connected to a first return material valve (61), the first return material valve (61) is connected to the oxygen release reactor (9), the oxygen release reactor (9) is connected to a second cyclone separator (42), the lower outlet of the second cyclone separator (42) is connected to a second return material standpipe (52), the second return material standpipe (52) is connected to a second return material valve (62), the second return material valve (62) is connected to the gasification reactor (8), and the top of the second cyclone separator (42) is connected to an airflow duct (10).

2. The biomass chemical chain gasification device according to claim 1, characterized in that: The airflow pipeline (10) is connected to an airflow branch pipe (11), and the airflow branch pipe (11) is connected to the gasification reactor (8) through a recirculation fan (12).

3. The biomass chemical chain gasification device according to claim 2, characterized in that: The oxidation reactor (3) is an isodiameter cylindrical structure.

4. The biomass chemical chain gasification device according to claim 3, characterized in that: The oxygen release reactor (9) and the gasification reactor (8) are an integrated structure. The oxygen release reactor (9) is an equal-diameter column structure. The gasification reactor (8) comprises a variable-diameter cone structure with a smaller top and a larger bottom and an equal-diameter column structure. The diameter of the oxygen release reactor (9) is equal to the minimum diameter of the variable-diameter cone structure. The maximum diameter of the equal-diameter column structure and the variable-diameter cone structure of the gasification reactor (8) are equal.

5. The biomass chemical chain gasification device according to claim 4, characterized in that: The lower side of the oxidation reactor (3) is provided with a first feed inlet (71), and the first feed inlet (71) forms an angle of 45°-60° with the horizontal direction.

6. The biomass chemical chain gasification device according to claim 5, characterized in that: The lower side of the gasification reactor (8) is provided with a second feed inlet (72), and the second feed inlet (72) forms an angle of 45°-60° with the horizontal direction.

7. The biomass chemical chain gasification device according to claim 6, characterized in that: The lower side of the oxygen release reactor (9) is provided with a third feed inlet (73), and the third feed inlet (73) forms an angle of 45°-60° with the horizontal direction.

8. The biomass chemical chain gasification device according to claim 7, characterized in that: The oxidation reactor (3) and the oxygen release reactor (9) are fast fluidized beds, and the gasification reactor (8) is a turbulent fluidized bed. A fluidized bed gas-solid outlet is provided at the junction of the reduced diameter and the equal diameter of the gasification reactor (8), and is connected to the feed inlet at the bottom of the oxidation reactor (3) through a third return valve (63).

9. A biomass chemical chain gasification method, using the biomass chemical chain gasification device according to claim 8, characterized in that: The following steps are involved: After the air from the oxidation reactor (3) fluidizes and oxidizes the oxygen carrier material, the oxygen carrier flows to the oxygen release reactor (9) through the first return valve (61). In the oxygen release reactor (9), the oxygen carrier particles are transported upward at a wind speed of 6-10 m / s and gaseous oxygen is released; The oxygen carrier after releasing oxygen is separated by the second cyclone separator (42) and enters the gasification reactor (8), and is mixed with the biomass particles to participate in the catalytic pyrolysis and gasification reaction of the biomass. The oxygen carrier then returns to the oxidation reactor (3) through the third return valve (63); In the lower part of the gasification reactor (8), the biomass is pyrolyzed and gasified to generate coke, synthesis gas, tar, and low-carbon hydrocarbons. At the same time, under the catalytic action of the oxygen carrier, part of the tar, low-carbon hydrocarbons and water react to generate synthesis gas. The synthesis gas passes through the oxygen release reactor (9) and enters the second cyclone separator (42) to be separated and enter the gas flow pipeline (10); Part of the gas in the gas flow duct (10) passes through the recirculation fan (12) and returns from the gas flow branch pipe (11) to the gasification reactor (8) for recirculation.

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