Device and method for preparing high-calorific-value low-carbon fuel from biomass

Abstract

The invention relates to a device for preparing high-calorific-value low-carbon fuel from biomass, and belongs to the technical field of chemical equipment. The device comprises a stock bin, a fluidized bed pyrolyzing furnace, an overflow channel, a fluidized bed gasification furnace and a cyclone separator which are sequentially connected, the cyclone separator is communicated with the fluidized bed pyrolyzing furnace, and the fluidized bed gasification furnace is connected with a microwave generator; the bottom of the fluidized bed pyrolyzing furnace is communicated with an oxygen-poor gas input pipeline, and the bottom of the fluidized bed gasifying furnace is communicated with an oxidizing gas input channel. The biomass gasification reaction is divided into a pyrolysis process and a gasification process by the double fluidized beds, the two processes are decoupled, and a plurality of functional groups related to hydrogen production are generated by low-temperature pyrolysis in the fluidized bed pyrolyzing furnace, so that the yield of hydrogen is increased; microwave heating is introduced into the fluidized bed gasification furnace, so that the gasification furnace can reach the required temperature more quickly, meanwhile, pyrolysis products are converted through microwave targeting energy, generation of tar and methane is remarkably reduced, and generation of hydrogen production reaction is facilitated, so that high-calorific-value low-carbon fuel is generated.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical equipment, and particularly relates to a device and method for producing high-calorie and low-carbon fuels from biomass. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the understanding of the overall background of the present invention, and is not necessarily to be regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] As the fourth-largest energy source after coal, oil, and natural gas, biomass not only has huge reserves and wide resource distribution, but also has the advantages of being renewable, green, and carbon-free. It can be used as an alternative energy source to traditional fossil fuels, alleviating the current energy shortage and reducing the pollution caused by energy use to the environment. Biomass gasification technology can convert the effective components in biomass into high-value-added fuels.

[0004] Conventional biomass gasification hydrogen production technologies include updraft or downdraft fixed beds, bubbling fluidized beds, circulating fluidized bed processes, etc., which perform thermal conversion on biomass. However, these methods have poor ability for the directional conversion of biomass, resulting in a low hydrogen content in the generated syngas and a low calorific value of the produced gas. There are methods in the prior art for reducing tar content with microwave assistance, but a single reactor cannot finely control the reaction conditions during the reaction process, making it difficult to further improve the effect of microwave assistance and resulting in low overall energy efficiency. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a device and method for producing high-calorie and low-carbon fuels from biomass. The pyrolysis-gasification process is carried out using a two-stage separation fluidized bed to decouple the biomass thermal conversion process. At the same time, a multi-energy cascade coupling strategy combining conventional thermal energy and microwave energy is adopted, so that each process can be carried out under the best conditions, improving the efficiency of biomass conversion, enhancing the effective utilization rate of carbon and hydrogen elements, and reducing the tar content.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] In a first aspect, a device for producing high-calorie and low-carbon fuels from biomass includes a silo, a fluidized bed pyrolysis furnace, an overflow channel, a fluidized bed gasification furnace, and a cyclone separator connected in sequence. The cyclone separator is connected to the fluidized bed pyrolysis furnace, and the fluidized bed gasification furnace is connected to a microwave generator; the bottom of the fluidized bed pyrolysis furnace is connected to an oxygen-deficient gas input pipeline, and the bottom of the fluidized bed gasification furnace is connected to an oxidizing gas input channel.

[0008] In a second aspect, a method for producing high-calorie and low-carbon fuels from biomass based on the above device includes the following processes:

[0009] Biomass in the silo enters the fluidized bed pyrolysis furnace and is pyrolyzed into pyrolysis products at 350 - 650 °C; the pyrolysis products enter the fluidized bed gasification furnace through the overflow channel and become gasification products at 700 - 1100 °C under the microwave assistance of the microwave generator; the gasification products are separated by a cyclone separator, the separated solids are transported back to the fluidized bed pyrolysis furnace for cyclic treatment, and the separated syngas is output as fuel.

[0010] The beneficial effects of the present invention are as follows:

[0011] 1. The present invention adopts a dual fluidized bed combining a fluidized bed pyrolysis furnace and a fluidized bed gasification furnace, decouples the biomass gasification reaction into two processes of pyrolysis and gasification, and controls their process conditions respectively, thus realizing the technical scheme of combining low-temperature pyrolysis and high-temperature gasification of biomass solid raw materials: low-temperature pyrolysis (350 - 650 °C) is carried out in the fluidized bed pyrolysis furnace to generate many hydrogen-related functional groups, increasing the hydrogen production; microwave directional heating is introduced in the fluidized bed gasification furnace to enable the gasification furnace to reach the required temperature (700 - 1100 °C) faster, and at the same time, the pyrolysis products are transformed by microwave targeted energy use, significantly reducing the generation of tar and methane, and also facilitating the occurrence of hydrogen production reaction to generate high-calorie low-carbon fuels.

[0012] 2. The present invention adopts a two-stage separation fluidized bed, which can provide more adjustable means for biomass thermal conversion and directionally regulate the selectivity and yield of biomass gasification products. In the fluidized bed pyrolysis furnace, flash pyrolysis occurs when the biomass raw material is heated by a conventional heating method, and the pyrolysis products and bed materials carry heat and enter the gasification section through the overflow device, reducing the input of high-quality energy such as microwave in the gasification section. Furthermore, the biomass raw material can be thermally converted in a step-by-step and orderly manner, and the high-temperature circulating bed materials after gasification can be cycled into the pyrolysis furnace as the heat source for pyrolysis, reducing the energy consumption of the entire circulation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0014] Figure 1 It is a schematic diagram of the device structure in Embodiment 1.

[0015] Among them, 1, silo; 2, feeder; 3, fluidized bed pyrolysis furnace; 4, overflow channel; 5, microwave generator; 6, waveguide; 7, fluidized bed gasification furnace; 8, cyclone separator; 9, waste heat recovery device; 10, gas dust removal device; 13, lean oxygen gas input pipeline; 14, oxidizing gas input channel; 20, blower; 21, gas flowmeter; 23, ash collector; 24, induced draft fan. DETAILED DESCRIPTION OF THE INVENTION

[0016] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0017] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0018] In a specific embodiment of the present invention, a device for producing high-calorie low-carbon fuel from biomass is provided, which includes a silo, a fluidized bed pyrolysis furnace, an overflow channel, a fluidized bed gasification furnace, and a cyclone separator connected in sequence. The cyclone separator is connected to the fluidized bed pyrolysis furnace, and the fluidized bed gasification furnace is connected to a microwave generator; the bottom of the fluidized bed pyrolysis furnace is connected to an oxygen-deficient gas input pipeline, and the bottom of the fluidized bed gasification furnace is connected to an oxidizing gas input channel.

[0019] Through the above settings, the pyrolysis and gasification processes are respectively carried out in the fluidized bed pyrolysis furnace and the fluidized bed gasification furnace to decouple and separately control the two processes. At the same time, combined with the multi-energy cascade coupling strategy of conventional heat energy and microwave energy, each process can be carried out under the best conditions, improving the efficiency of biomass conversion, reducing the tar content, providing a variety of regulation means, and enabling biomass to be directionally converted into high-calorie low-carbon fuel mainly composed of hydrogen and carbon monoxide.

[0020] Optionally, the silo and the fluidized bed pyrolysis furnace are connected through a feeder; it is used to quantitatively transport biomass into the fluidized bed pyrolysis furnace.

[0021] Optionally, the overflow channel connects the upper part of the fluidized bed pyrolysis furnace and the bottom of the fluidized bed gasification furnace. The materials in the fluidized bed pyrolysis furnace gradually rise with the fluidization process, and the materials pyrolyzed to the set state are output to the bottom of the fluidized bed gasification furnace in an overflow manner at the upper part of the fluidized bed pyrolysis furnace. The materials in the fluidized bed gasification furnace gradually rise with the fluidization process and become gasified materials under the action of the microwave emitted by the microwave generator.

[0022] Optionally, the fluidized bed gasification furnace and the microwave generator are connected through a waveguide; the waveguide is used to transport microwaves to a set position in the fluidized bed gasification furnace and prevent the materials in the fluidized bed gasification furnace from entering the microwave generator, so as to solve the problems of low hydrogen content, high methane and tar content in the syngas in the way of coupling conventional heat energy and microwave energy.

[0023] Optionally, the solid outlet of the cyclone separator is connected to the fluidized bed pyrolysis furnace, and the solids enter the fluidized bed pyrolysis furnace for recycling to provide heat for the fluidized bed pyrolysis furnace; the gas outlet of the cyclone separator is sequentially connected to the waste heat recovery device and the gas dust removal device, and after being processed, it enters other downstream processes.

[0024] Optionally, the oxygen-deficient gas input pipeline and the oxidizing gas input channel respectively pass through the waste heat recovery device. After the syngas is recovered from waste heat, the temperature of the syngas is reduced to 300-350 °C, and it remains above 300 °C before entering the gas dust removal device to prevent condensable substances from condensing; the oxygen-deficient gas is heated to 500-800 °C, and the oxidizing gas is heated to 350-550 °C to keep the temperature of the fluidized bed device stable.

[0025] Optionally, the fluidized bed pyrolysis furnace is a bubbling bed or a turbulent bed, and its superficial gas velocity is 0.3-0.7 m / s; the fluidized bed gasification furnace is a fast bed, and its superficial gas velocity is 4-15 m / s, and different types of equipment are used to adjust the gas velocity.

[0026] Optionally, a slag outlet is provided at the bottom of the fluidized bed gasification furnace, and the slag outlet is connected to a dust collector; it is used for centralized treatment of slag.

[0027] Optionally, the fluidization carrier in the fluidized bed pyrolysis furnace and the fluidized bed gasification furnace is wear-resistant and high-temperature-resistant particles, including one or more of sand, dolomite, olivine, alumina balls, silicon carbide balls, ceramic particles and white corundum particles, and the particle size is 0.1-3.0 mm.

[0028] In a specific embodiment of the present invention, a method for producing high-calorie low-carbon fuel from biomass based on the above device is provided, including the following processes:

[0029] The biomass in the silo enters the fluidized bed pyrolysis furnace and is pyrolyzed into pyrolysis products at 350-650 °C; the pyrolysis products enter the fluidized bed gasification furnace through the overflow channel and become gasification products at 700-1100 °C under the microwave-assisted action of the microwave generator; the gasification products are separated by a cyclone separator, and the separated solids are transported back to the fluidized bed pyrolysis furnace for cyclic treatment, and the separated syngas is output as fuel.

[0030] In the above process, the biomass treatment process is decoupled into two processes of pyrolysis and gasification, and the two processes are respectively controlled, which can directionally regulate the selectivity and yield of biomass gasification products; and the microwave-assisted action only occurs in the fluidized bed gasification furnace to reduce the consumption of high-quality energy.

[0031] Optionally, an oxygen-depleted gas is introduced into the fluidized bed pyrolysis furnace for fluidization, and the oxygen-depleted gas includes but is not limited to water vapor, nitrogen, etc.

[0032] Optionally, an oxidizing gas is introduced into the fluidized bed gasifier for fluidization, and the oxidizing gas includes but is not limited to: oxygen, water vapor, or a mixture of oxygen and water vapor.

[0033] Optionally, the ash produced by the fluidized bed gasifier is collected and cleaned by an ash collector.

[0034] Optionally, the power of the microwave generator is: 2.0-5.0 MW / m 3 The energy density is evenly distributed, and in the sparse phase area, it is 0.5~2.0MW / m 3 The energy density is evenly arranged. The larger microwave power in the dense phase area is used to maintain the gasification temperature and promote the deep gasification of the pyrolysis products. The lower microwave power in the sparse phase area is sufficient to crack and reform tar and methane, and react with gasifying agents such as oxygen or water vapor to produce high calorific value synthesis gas mainly composed of CO / H2. This arrangement can convert the pyrolysis products in a targeted manner with low energy consumption.

[0035] Optionally, a waste heat recovery device collects gas heat of the synthesis gas and heats the oxygen-depleted gas and the oxidizing gas separately to reduce system energy consumption.

[0036] Optionally, the synthesis gas is output after being dust-removed by a gas dust removal device.

[0037] Example 1

[0038] A device for producing high calorific value and low carbon fuel from biomass, comprising a silo 1, a feeder 2, a fluidized bed pyrolysis furnace 3, an overflow channel 4, a fluidized bed gasification furnace 7 and a cyclone separator 8 which are connected in sequence, the cyclone separator 8 being connected to the fluidized bed pyrolysis furnace 3, the fluidized bed gasification furnace 7 being connected to a microwave generator 5; the bottom of the fluidized bed pyrolysis furnace 3 being connected to an oxygen-depleted gas input pipeline 13, the bottom of the fluidized bed gasification furnace 7 being connected to an oxidizing gas input channel 14.

[0039] The overflow channel 4 connects the upper part of the fluidized bed pyrolysis furnace 3 and the bottom of the fluidized bed gasification furnace 7. The material in the fluidized bed pyrolysis furnace 3 gradually rises with the fluidization process. The material pyrolyzed to a set state is output to the bottom of the fluidized bed gasification furnace 7 in an overflow manner at the upper part of the fluidized bed pyrolysis furnace 3. The material in the fluidized bed gasification furnace 7 gradually rises with the fluidization process and becomes a gasified material including pyrolysis gas under the action of microwaves emitted by the microwave generator 5.

[0040] The overflow channel 4 is specifically a return device, which is used for unidirectional transportation of pyrolysis products and bed materials.

[0041] The fluidized bed gasifier 7 and the microwave generator 5 are connected through a waveguide 6; the waveguide 6 is used to transport microwaves to a set position in the fluidized bed gasifier 7 and prevent the materials in the fluidized bed gasifier 7 from entering the microwave generator 5, so as to solve the problems of low hydrogen content, high methane and tar content in the syngas in the way of coupling conventional thermal energy and microwave energy.

[0042] The solid outlet of the cyclone separator 8 is connected to the fluidized bed pyrolysis furnace 3, and the solids with higher temperature enter the fluidized bed pyrolysis furnace 3 for recycling and provide heat for the fluidized bed pyrolysis furnace 3; the gas outlet of the cyclone separator 8 is successively connected to the waste heat recovery device 9 and the gas dust removal device 10, and after being processed, it enters other downstream technological processes.

[0043] The oxygen-deficient gas input pipeline 13 and the oxidizing gas input channel 14 respectively pass through the waste heat recovery device 9, and use the recovered heat of the syngas to heat the gases transported into the fluidized bed pyrolysis furnace 3 and the fluidized bed gasifier 7.

[0044] Gas flow meters 21 are respectively arranged on the oxygen-deficient gas input pipeline 13 and the oxidizing gas input channel 14, which are used to monitor the gas flow rate and perform quantitative control.

[0045] The oxygen-deficient gas input pipeline 13 and the oxidizing gas input channel 14 are respectively powered by blowers 20; the gas dust removal device 10 is connected to an induced draft fan 24 to provide power.

[0046] The fluidized bed pyrolysis furnace 3 is a bubbling bed, and the apparent gas velocity regulation range is 0.3 - 0.7 m / s; the fluidized bed gasifier 7 is a fast bed, and the apparent gas velocity regulation range is 4 - 15 m / s.

[0047] A slag outlet is arranged at the bottom of the fluidized bed gasifier 7, and the slag outlet is connected to an ash collector 23; it is used for centralized treatment of ash and slag.

[0048] A method for producing high calorific value low-carbon fuel from biomass based on the device of this embodiment includes the following processes:

[0049] The biomass in the silo 1 is quantitatively transported into the fluidized bed pyrolysis furnace 3 through the feeder 2, and the apparent gas velocity of the fluidized bed pyrolysis furnace 3 is adjusted to 0.3 m / s, so that the biomass is pyrolyzed into pyrolysis products at 600 °C; the pyrolysis products enter the fluidized bed gasifier 7 through the overflow channel 4, and the apparent gas velocity of the fluidized bed gasifier 7 is adjusted to 10 m / s, so that the pyrolysis products become gasification products in an environment of 850 °C and under the microwave-assisted action of the microwave generator 5; the gasification products are separated by the cyclone separator 8, the separated solids are transported back to the fluidized bed pyrolysis furnace 3 for cyclic treatment, and the separated syngas is output as fuel.

[0050] The gas separated by the cyclone separator 8 sequentially passes through the waste heat recovery device 9 to recover waste heat, and is output after being dust-removed by the gas dust removal device 10; the waste heat recovery device 9 heats the oxygen-deficient gas and the oxidizing gas respectively to reduce energy consumption.

[0051] Steam is introduced into the fluidized bed pyrolysis furnace 3 for fluidization, and the apparent gas velocity in the pyrolysis furnace is controlled at 0.3 m / s, and its flow pattern is maintained in the bubbling fluidization state.

[0052] A mixture of 95% steam and 5% oxygen is introduced into the fluidized bed gasifier 7 for fluidization, and the apparent gas velocity in the gasifier is controlled at 6 m / s, and its flow pattern is maintained in the fast fluidization state.

[0053] The ash generated by the fluidized bed gasifier 7 is collected and cleaned by the ash collector 23.

[0054] The biomass raw material is wood chip particles, the feeding size is not more than 30 mm, and its moisture content is 10%. The mass ratio of the hourly biomass feeding amount to the bed material in the pyrolysis furnace cavity is 1:10.

[0055] The fluidization carriers in the fluidized bed pyrolysis furnace 3 and the fluidized bed gasifier 7 are wear-resistant and high-temperature-resistant dolomite particles with a particle size of 100 μm.

[0056] The power of the microwave generator is: uniformly arranged according to an energy density of 4.0 MW / m in the dense phase region, and uniformly arranged according to an energy density of 1.0 MW / m in the dilute phase region. 3 energy density, and uniformly arranged according to an energy density of 1.0 MW / m in the dilute phase region. 3 energy density.

[0057] According to the above settings, through experiments, the tar content at the gasifier outlet can be reduced to <100 mg / Nm 3 , and the effective components of the syngas are: 27% CO, 48% H2, 20% CO2, 3% CH4, 2% C n H m The calorific value of the fuel gas is 2830 kcal / Nm 3 .

[0058] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An apparatus for producing high-calorie and low-carbon fuel from biomass, characterized in that, It includes a silo, a fluidized bed pyrolysis furnace, an overflow channel, a fluidized bed gasifier, and a cyclone separator connected in sequence. The cyclone separator is connected to the fluidized bed pyrolysis furnace, and the fluidized bed gasifier is connected to a microwave generator. The bottom of the fluidized bed pyrolysis furnace is connected to an oxygen-deficient gas input pipeline, and the bottom of the fluidized bed gasifier is connected to an oxidizing gas input channel.

2. The device for producing high-calorie and low-carbon fuel from biomass according to claim 1, characterized in that, The silo is connected to the fluidized bed pyrolysis furnace through a feeder.

3. The device for producing high-calorie and low-carbon fuel from biomass according to claim 1, characterized in that, The overflow channel connects the upper part of the fluidized bed pyrolysis furnace and the bottom of the fluidized bed gasifier. Or, the fluidized bed pyrolysis furnace is a bubbling bed or a turbulent bed, and its superficial gas velocity is 0.3 - 0.7 m / s. The fluidized bed gasifier is a fast bed, and its superficial gas velocity is 4 - 15 m / s. Or, a slag outlet is provided at the bottom of the fluidized bed gasifier, and the slag outlet is connected to a dust collector for centralized treatment of slag.

4. The device for producing high-calorie and low-carbon fuel from biomass according to claim 1, characterized in that, The fluidized bed gasifier and the microwave generator are connected through a waveguide.

5. The device for producing high calorific value and low-carbon fuel from biomass according to claim 1, wherein The solid outlet of the cyclone separator is connected to the fluidized bed pyrolysis furnace, and the gas outlet of the cyclone separator is connected to a waste heat recovery device and a gas dust removal device in sequence.

6. The device for producing high calorific value and low-carbon fuel from biomass according to claim 5, wherein The oxygen-deficient gas input pipeline and the oxidizing gas input channel respectively pass through the waste heat recovery device.

7. The device for producing high calorific value and low-carbon fuel from biomass according to claim 1, characterized in that, The fluidization carrier in the fluidized bed pyrolysis furnace and the fluidized bed gasifier is wear-resistant and high-temperature-resistant particles, including one or more of sand, dolomite, olivine, alumina balls, silicon carbide balls, ceramic particles, and white corundum particles, with a particle size of 0.1 - 3.0 mm.

8. A method for producing high-calorie and low-carbon fuels from biomass based on the device according to any one of claims 1-7, characterized in that, It includes the following processes: The biomass in the silo enters the fluidized bed pyrolysis furnace and is pyrolyzed into pyrolysis products at 350 - 650 °C. The pyrolysis products enter the fluidized bed gasifier through the overflow channel and become gasification products at 700 - 1100 °C under the microwave-assisted action of the microwave generator. The gasification products are separated by the cyclone separator. The separated solids are transported back to the fluidized bed pyrolysis furnace for cyclic treatment, and the separated syngas is output as fuel.

9. The method for producing high calorific value and low-carbon fuel from biomass according to claim 8, characterized in that, An oxygen-deficient gas is introduced into the fluidized bed pyrolysis furnace for fluidization. The oxygen-deficient gas includes water vapor, nitrogen, and argon. Or, an oxidizing gas is introduced into the fluidized bed gasifier for fluidization. The oxidizing gas includes but is not limited to oxygen, water vapor, or a mixture of oxygen and water vapor. Or, the power of the microwave generator is: evenly arranged at an energy density of 2.0 - 5.0 MW / m in the dense phase region 3 and evenly arranged at an energy density of 0.5 - 2.0 MW / m in the lean phase region 3 for uniform energy density distribution.

10. The method for producing high calorific value and low-carbon fuel from biomass according to claim 8, wherein, The waste heat recovery device collects the gas heat of the syngas and heats the oxygen-deficient gas and the oxidizing gas respectively. Or, the syngas is output after being dust-removed by the gas dust removal device.

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