System for producing methane through biomass pyrolysis gasification

Abstract

The utility model relates to a system for producing methane by biomass pyrolysis gasification, which comprises a riser reactor, a first gas-solid separator, a bubbling fluidized bed reactor and a second gas-solid separator, the riser reactor comprises a biomass raw material inlet, a solid heat carrier inlet, a pyrolysis product outlet and a first fluidized gas inlet; the first gas-solid separator comprises a pyrolysis product inlet, an oil-rich pyrolysis gas outlet and a pyrolysis semicoke outlet; the bubbling fluidized bed reactor comprises a pyrolysis semi-coke inlet, a crude synthesis gas outlet containing gasified semi-coke, a slag outlet, a solid heat carrier outlet, a second fluidizing gas inlet and a gasified semi-coke inlet; the second gas-solid separator comprises a gasified semicoke-containing crude synthesis gas inlet, a crude synthesis gas outlet and a gasified semicoke outlet; the pyrolysis product outlet is communicated with the pyrolysis product inlet, the pyrolysis semi-coke outlet is communicated with the pyrolysis semi-coke inlet, the gasified semi-coke-containing crude synthesis gas outlet is communicated with the gasified semi-coke-containing crude synthesis gas inlet, and the gasified semi-coke outlet is communicated with the gasified semi-coke inlet.

Description

Technical Field

[0001] The utility model relates to the fields of biomass pyrolysis gasification and methane production, in particular to a system for producing methane by biomass pyrolysis gasification. Background Art

[0002] At present, the conventional biomass gasification technology mixes biomass raw materials with oxygen and steam through a single-stage fixed bed or fluidized bed reactor, and a chemical reaction occurs below 1000°C to generate raw syngas. In addition to components such as hydrogen, carbon monoxide, carbon dioxide, and methane, the raw syngas also contains difficult-to-treat tar and other impurities. Tar in the syngas is prone to condense and deposit in the low-temperature areas of downstream devices, causing pipeline blockages, reducing the overall production efficiency of the gasification process, and bringing high operation and maintenance costs. To solve the tar problem at the gasifier outlet, generally, the temperature at the gasifier outlet is increased (>1300°C) through a partial oxidation device, but this causes problems such as low content of effective gases (hydrogen, carbon monoxide, methane, etc.) in the raw syngas, high oxygen consumption of the entire gasification system, and low cold gas efficiency of gasification. Summary of the Utility Model

[0003] In view of the above-mentioned disadvantages of the prior art, the purpose of the present utility model is to provide a system for producing methane by biomass pyrolysis gasification. The technical problem to be solved by the present utility model is to overcome the tar problem caused by the low temperature at the gasifier outlet during the existing biomass gasification process, or the high energy consumption during the gasification process caused by increasing the temperature. In addition, methane is produced through the hierarchical and quality-separated utilization of biomass, and oil products are richly produced, significantly reducing energy consumption. The hydrogenation gasification process significantly reduces oxygen consumption and further reduces the cost of producing methane through biomass gasification. The present utility model solves the above technical problems through the following technical solutions.

[0004] The present utility model provides a system for producing methane by biomass pyrolysis gasification, including a riser reactor, a first gas-solid separator, a bubbling fluidized bed reactor, and a second gas-solid separator. The riser reactor includes a biomass raw material inlet, a solid heat carrier inlet, a pyrolysis product outlet, and a first fluidizing gas inlet; the first gas-solid separator includes a pyrolysis product inlet, a pyrolysis gas outlet rich in oil products, and a pyrolysis semi-coke outlet; the bubbling fluidized bed reactor includes a pyrolysis semi-coke inlet, a raw syngas outlet containing gasified semi-coke, a slag outlet, a solid heat carrier outlet, a second fluidizing gas inlet, and a gasified semi-coke inlet; the second gas-solid separator includes a raw syngas inlet containing gasified semi-coke, a raw syngas outlet, and a gasified semi-coke outlet; the pyrolysis product outlet is communicated with the pyrolysis product inlet, the pyrolysis semi-coke outlet is communicated with the pyrolysis semi-coke inlet, the raw syngas outlet containing gasified semi-coke is communicated with the raw syngas inlet containing gasified semi-coke, the gasified semi-coke outlet is communicated with the gasified semi-coke inlet, and the solid heat carrier outlet is communicated with the solid heat carrier inlet.

[0005] In some embodiments of the present utility model, the riser reactor sequentially includes a riser reactor gas chamber, a material mixing zone, and a rapid riser zone from bottom to top. A first gas distribution plate is provided between the riser reactor gas chamber and the material reaction zone. The first fluidizing gas inlet is communicated with the riser reactor gas chamber. The biomass raw material inlet and the solid heat carrier inlet are respectively communicated with the material mixing zone. The pyrolysis product outlet is communicated with the rapid riser zone.

[0006] In some embodiments of the present utility model, the superficial gas velocity in the rapid riser zone is 1.5 to 2.5 times that in the material mixing zone.

[0007] In some embodiments of the present utility model, the height ratio of the rapid riser zone to the material mixing zone is 7 to 12.

[0008] In some embodiments of the present utility model, the diameter ratio of the rapid riser zone to the material mixing zone is 0.75 to 0.9.

[0009] In some embodiments of the present utility model, the bubbling fluidized bed reactor sequentially includes a bubbling fluidized bed reactor gas chamber, a dense phase reaction zone, and a dilute phase reaction zone from bottom to top. A second gas distribution plate is provided between the bubbling fluidized bed reactor gas chamber and the dense phase reaction zone. The second fluidizing gas inlet is communicated with the bubbling fluidized bed reactor gas chamber. The pyrolytic char inlet, the slag outlet, the solid heat carrier outlet, and the semi-coke inlet are respectively communicated with the dense phase reaction zone. The crude syngas outlet containing gasified semi-coke is communicated with the dilute phase reaction zone.

[0010] In some embodiments of the present utility model, a third fluidizing gas inlet is further included, and the third fluidizing gas inlet is communicated with the bubbling fluidized bed reactor gas chamber.

[0011] In some embodiments of the present utility model, gas nozzles are provided on the second gas distribution plate.

[0012] In some embodiments of the present utility model, the fluidization density in the dense phase reaction zone is 200 - 600 kg / m 3 .

[0013] In some embodiments of the present utility model, the solid content in the gas in the dilute phase reaction zone is less than 50 kg / m 3 .

[0014] In some embodiments of the present utility model, the height ratio of the dilute phase reaction zone to the dense phase reaction zone is 1.5 - 2.

[0015] In some embodiments of the present utility model, the fluidizing gas at the third fluidizing gas inlet includes oxygen and water vapor.

[0016] In some embodiments of the present utility model, the pyrolysis semicoke outlet and the pyrolysis semicoke inlet are connected through a first gas-solid separator feed pipe.

[0017] In some embodiments of the present utility model, the gasification semicoke outlet and the gasification semicoke inlet are connected through a second gas-solid separator feed pipe.

[0018] In some embodiments of the present utility model, the solid heat carrier outlet and the solid heat carrier inlet are connected through a solid heat carrier pipeline.

[0019] In some embodiments of the present utility model, the fluidizing gas at the first fluidizing gas inlet is hydrogen, wherein the hydrogen is sourced from a hydrogen production device outside the system boundary or hydrogen-rich gas separated and purified within the system.

[0020] In some embodiments of the present utility model, the fluidizing gas at the second fluidizing gas inlet includes hydrogen and water vapor.

[0021] In some embodiments of the present utility model, the hydrogen at the first fluidizing gas inlet is sourced from a hydrogen production device outside the system boundary or hydrogen-rich gas separated and purified within the system.

[0022] In some embodiments of the present utility model, the hydrogen at the second fluidizing gas inlet is sourced from a hydrogen production device outside the system boundary or hydrogen-rich gas separated and purified within the system.

[0023] In some embodiments of the present utility model, the raw syngas outlet is sequentially connected to a waste heat recovery unit, a dust removal unit, a syngas scrubbing unit, a carbon monoxide shift unit, and a methane unit.

[0024] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0025] In the system for producing methane by biomass pyrolysis gasification of the present utility model, the tube reactor and the bubbling fluidized bed reactor are coupled to realize the circulation of the solid heat carrier and the full utilization of energy.

[0026] By adopting this method, during the process of producing methane by biomass gasification, the consumption of oxygen is significantly reduced, the energy utilization rate of the whole process is remarkably improved, and oil products are richly produced while producing methane, realizing the hierarchical and quality-separated utilization in the conversion process of biomass raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of the system for producing methane by biomass pyrolysis gasification of the present utility model (wherein, the waste heat recovery unit, the dust removal unit, the syngas scrubbing unit, the carbon monoxide shift unit, and the methane unit are not shown).

[0028] Reference numerals:

[0029] 1 riser reactor

[0030] 101 riser reactor gas chamber

[0031] 102 material mixing zone

[0032] 103 rapid riser zone

[0033] 2 bubbling fluidized bed reactor

[0034] 201 bubbling fluidized bed reactor gas chamber

[0035] 202 dense-phase reaction zone

[0036] 203 dilute-phase reaction zone

[0037] 3 first fluidizing gas inlet

[0038] 4 biomass raw material inlet

[0039] 5 first gas distributor

[0040] 6 solid heat carrier inlet

[0041] 7 pyrolysis product outlet

[0042] 8 pyrolysis product inlet

[0043] 9 first gas-solid separator

[0044] 10 pyrolysis gas outlet rich in oil products

[0045] 11 pyrolytic char outlet

[0046] 12 downcomer of the first gas-solid separator

[0047] 13 pyrolytic char inlet

[0048] 14 solid heat carrier outlet

[0049] 15 second gas distributor

[0050] 16 second fluidizing gas inlet

[0051] 17 third fluidizing gas inlet

[0052] 18 gasification char inlet

[0053] 19 gas nozzle

[0054] 20 slag outlet

[0055] 21 outlet of raw syngas containing gasification char

[0056] 22 Inlet of raw syngas containing gasified semicoke

[0057] 23 Second gas-solid separator

[0058] 24 Outlet of raw syngas

[0059] 25 Outlet of gasified semicoke

[0060] 26 Discharge pipe of the second gas-solid separator

[0061] 27 Solid heat carrier pipeline Detailed implementation manners

[0062] In the description of the present utility model, it should be noted that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in this technology to understand and read, and are not used to limit the implementable conditions of the present utility model. Therefore, they do not have substantial technical significance. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects that the present utility model can produce and the purposes that can be achieved, should still fall within the scope that can be covered by the technical content disclosed in the present utility model. At the same time, the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0063] In the description of the present utility model, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0064] In addition, in the description of the present utility model, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0065] The following details the system for producing methane by biomass pyrolysis gasification according to the present utility model.

[0066] An embodiment of the present utility model provides a system for producing methane by biomass pyrolysis gasification, which includes a riser reactor 1, a first gas-solid separator 9, a bubbling fluidized bed reactor 2, and a second gas-solid separator 23. The riser reactor 1 and the bubbling fluidized bed reactor 2 are connected through a material pipeline to realize the transfer of solid materials between the riser reactor 1 and the bubbling fluidized bed reactor 2.

[0067] The riser reactor 1 includes a biomass raw material inlet 4, a solid heat carrier inlet 6, a pyrolysis product outlet 7, and a first fluidizing gas inlet 3; the first gas-solid separator 9 includes a pyrolysis product inlet 8, a pyrolysis gas outlet 10 rich in oil products, and a pyrolysis semicoke outlet 11; the bubbling fluidized bed reactor 2 includes a pyrolysis semicoke inlet 13, a raw synthesis gas outlet 21 containing gasified semicoke, a slag outlet 20, a solid heat carrier outlet 14, a second fluidizing gas inlet 16, and a gasified semicoke inlet 18; the second gas-solid separator 23 includes a raw synthesis gas inlet 22 containing gasified semicoke, a raw synthesis gas outlet 24, and a gasified semicoke outlet 25; the pyrolysis product outlet 7 is communicated with the pyrolysis product inlet 8, the pyrolysis semicoke outlet 11 is communicated with the pyrolysis semicoke inlet 13, the raw synthesis gas outlet 21 containing gasified semicoke is communicated with the raw synthesis gas inlet of the gasified semicoke, the gasified semicoke outlet 25 is communicated with the gasified semicoke inlet 18, and the solid heat carrier outlet 14 is communicated with the solid heat carrier inlet 6.

[0068] In the system for producing methane by biomass pyrolysis gasification provided by the present utility model, the riser reactor 1 is used for mixing biomass with a solid heat carrier and undergoing a rapid hydro-pyrolysis reaction to generate pyrolytic char and pyrolysis gas rich in oil products. Specifically: The riser reactor 1 sequentially includes a riser reactor gas chamber 101, a material mixing zone 102, and a rapid lifting zone 103 from the bottom to the top. A first gas distribution plate 5 is provided between the riser reactor gas chamber 101 and the material reaction zone. Optionally, the first gas distribution plate 5 is horizontally arranged and parallel to the bottom of the riser reactor 1 for dividing the riser reactor gas chamber 101 and the material mixing zone 102. The first fluidizing gas inlet 3 is provided on the side wall of the riser reactor gas chamber 101, and the first fluidizing gas inlet 3 communicates with the riser reactor gas chamber 101. The fluidizing gas in the first fluidizing gas inlet 3 can be, for example, hydrogen. The biomass raw material inlet 4 and the solid heat carrier inlet 6 are respectively provided on the side wall of the material mixing zone 102, and the biomass raw material inlet 4 and the solid heat carrier inlet 6 respectively communicate with the material mixing zone 102. The pyrolysis product outlet 7 is provided at the top of the rapid lifting zone 103 of the riser reactor 1, and the pyrolysis product outlet 7 communicates with the rapid lifting zone 103. The pyrolysis product outlet 7 is connected to a first gas-solid separator 9 through a gas pipeline. The temperature of the pyrolysis product outlet 7 is 500 - 600 °C, and the pressure is 3.0 - 7.0 MpaG. Optionally, the temperature can be, for example, 500 - 550 °C or 550 - 600 °C, etc. The pressure can be, for example, 3.0 - 5.0 MPaG or 5.0 - 7.0 MPaG, etc. The temperature of the pyrolysis gas outlet 10 rich in oil products is 500 - 600 °C, and the pressure is 3.0 - 7.0 MpaG. Optionally, the temperature can be, for example, 500 - 550 °C or 550 - 600 °C, etc. The pressure can be, for example, 3.0 - 5.0 MPaG or 5.0 - 7.0 MPaG, etc. The pyrolysis product includes methane, hydrogen, carbon monoxide, carbon dioxide, and other organic compounds. Further, the volume percentage of methane in the pyrolysis product is 20 - 30 vol%. Optionally, the volume percentage of methane in the pyrolysis product can be, for example, 20 - 25 vol% or 25 - 30 vol%, etc. The volume percentage of hydrogen in the pyrolysis product is 10 - 15 vol%. Optionally, the volume percentage of hydrogen in the pyrolysis product can be, for example, 10 - 12 vol% or 12 - 15 vol%, etc. The volume percentage of carbon monoxide in the pyrolysis product is 25 - 35 vol%. Optionally, the volume percentage of carbon monoxide in the pyrolysis product can be, for example, 25 - 30 vol% or 30 - 35 vol%, etc. The volume percentage of carbon dioxide in the pyrolysis product is 30 - 40 vol%. Optionally, the volume percentage of carbon dioxide in the pyrolysis product can be, for example, 30 - 35 vol% or 35 - 40 vol%, etc.The volume percentage of the other organic compound in the pyrolysis product is 3-15 vol%. Optionally, the volume percentage of the other organic compound in the pyrolysis product can be, for example, 3-5 vol%, 5-10 vol%, or 10-15 vol%, etc.

[0069] Among them, the material mixing zone 102 and the rapid lifting zone 103 mainly have different gas velocities through variable diameters (the diameter of the material mixing zone 102 is larger than that of the rapid lifting zone 103, and the diameter ratio of the rapid lifting zone 103 to the material mixing zone 102 is 0.75-0.9. The low gas velocity in the material mixing zone 102 ensures sufficient mixing and heat exchange between the biomass raw material and the solid heat carrier, and promotes the rapid pyrolysis reaction of the biomass raw material. The superficial gas velocity of the rapid lifting zone 103 is 1.5-2.5 times that of the material mixing zone 102, and can be optionally 1.5-2 times, 2-2.5 times, etc. The height ratio of the rapid lifting zone 103 to the material mixing zone 102 is 7-12, and can be optionally 7-10 or 10-12, etc. The advantages of the above settings are as follows: after the biomass and the heat carrier are fully mixed and heat exchanged, a pyrolysis reaction occurs to produce bio-oil. By controlling the residence time of the bio-oil in the riser reactor through the rapid lifting zone, secondary reactions are avoided and the oil product yield is reduced; in addition, the upper outlet of the riser reactor is higher than the top of the bubbling fluidized bed, which is convenient for the flow of solid materials and the layout of equipment.

[0070] In the system for producing methane by biomass pyrolysis gasification provided by the present utility model, the first gas-solid separator 9 is provided with a pyrolysis product inlet 8, a pyrolysis gas outlet 10 rich in oil products, and a pyrolysis char outlet 11; the pyrolysis char outlet 11 and the pyrolysis char inlet 13 are communicated through a first gas-solid separator discharge pipe 12. The first gas-solid separator 9 includes one or more inertial or cyclone separators. The total separation efficiency range of the first gas-solid separator 9 is 95-99%, and dp50 is 10-30 microns.

[0071] In the system for producing methane by biomass pyrolysis gasification provided by the present utility model, the bubbling fluidized bed reactor 2 is used for the gasification reaction of pyrolytic char with a mixture of steam, hydrogen, and oxygen (where oxygen is optional) to generate raw syngas containing gasified char and slag. The bubbling fluidized bed reactor 2 successively includes a bubbling fluidized bed reactor gas chamber 201, a dense-phase reaction zone 202, and a dilute-phase reaction zone 203 from the bottom to the top. A second gas distribution plate 15 is provided between the bubbling fluidized bed reactor gas chamber 201 and the dense-phase reaction zone 202. Optionally, the second gas distribution plate 15 is horizontally arranged and is used to divide the bubbling fluidized bed reactor gas chamber 201 and the dense-phase reaction zone 202. The second fluidizing gas inlet 16 is provided on the side wall of the bubbling fluidized bed reactor gas chamber 201, and the second fluidizing gas inlet 16 communicates with the bubbling fluidized bed reactor gas chamber 201. Among them, the fluidizing gas in the second fluidizing gas inlet 16 mainly contains a mixture of steam and hydrogen. The pyrolytic char inlet 13, the slag outlet 20, the solid heat carrier outlet 14, and the gasified char inlet 18 are respectively arranged on the side wall of the dense-phase reaction zone 202, and the pyrolytic char inlet 13, the slag outlet 20, the solid heat carrier outlet 14, and the gasified char inlet 18 respectively communicate with the dense-phase reaction zone 202. The raw syngas outlet 21 containing gasified char is provided at the top of the dilute-phase reaction zone 203, and the raw syngas outlet 21 containing gasified char communicates with the dilute-phase reaction zone 203. The raw syngas outlet 21 containing gasified char is connected to the second gas-solid separator 23 through a gas pipeline, and the solid heat carrier outlet 14 is connected to the solid heat carrier inlet 6 through a solid heat carrier pipeline 27. The temperature of the raw syngas outlet 24 of the bubbling fluidized bed reactor 2 containing gasified char is 800 - 900 °C, and the pressure is 3.0 - 7.0 MPaG; optionally, the temperature is, for example, 800 - 850 °C or 850 - 900 °C, etc. The pressure can be, for example, 3.0 - 5.0 MPaG, or 5.0 - 7.0 MPaG, etc. The temperature of the raw syngas outlet 24 of the raw syngas outlet 24 containing gasified char is 800 - 900 °C, and the pressure is 3.0 - 7.0 MPaG; optionally, the temperature is, for example, 800 - 850 °C or 850 - 900 °C, etc. The pressure can be, for example, 3.0 - 5.0 MPaG or 5.0 - 7.0 MPaG, etc. The raw syngas is a variety of methane, hydrogen, carbon monoxide, carbon dioxide, etc. The volume percentage of methane in the raw syngas is 25 - 47 vol%. Optionally, the volume percentage of methane in the raw syngas can be, for example, 25 - 35 vol% or 35 - 47 vol%, etc. The volume percentage of hydrogen in the raw syngas is 15 - 35 vol%. Optionally, the volume percentage of hydrogen in the raw syngas can be, for example, 15 - 20 vol%, 20 - 30 vol%, or 30 - 35 vol%, etc. The volume percentage of carbon monoxide in the raw syngas is 8 - 20 vol%.Optionally, the volume percentage of carbon monoxide in the raw syngas may be, for example, 8-10 vol%, 10-15 vol%, or 15-20 vol% etc. The volume percentage of carbon dioxide in the raw syngas is 10-25 vol%. Optionally, the volume percentage of carbon dioxide in the raw syngas may be, for example, 20-30 vol%, 20-25 vol%, or 25-30 vol% etc.

[0072] Among them, the difference between the dense-phase reaction zone 202 and the dilute-phase reaction zone 203 lies in the concentration of the fixed particles. In this example, it is bubbling fluidization, and the fluidization density of the dense-phase reaction zone 202 is 200-600 kg / m 3 . The solid content in the gas of the dilute-phase reaction zone 203 is less than 50 kg / m 3 , and it decreases as the height increases. The height ratio range of the dilute-phase reaction zone 203 and the dense-phase reaction zone 202 is: 1.5-2.

[0073] In the system for producing methane by biomass pyrolysis gasification provided by the present utility model, a gas nozzle 19 is provided on the second gas distribution plate 15.

[0074] In the system for producing methane by biomass pyrolysis gasification provided by the present utility model, a third fluidizing gas inlet 17 is further included, and the third fluidizing gas inlet 17 is communicated with the gas chamber 201 of the bubbling fluidized bed reactor. Specifically, the fluidizing gas of the third fluidizing gas inlet 17 includes oxygen and water vapor. Preferably, the position of the third fluidizing gas inlet 17 is higher than the position of the second fluidizing gas inlet 16. The third fluidizing gas inlet 17 is closer to the gas nozzle 19 than the second fluidizing gas inlet 16.

[0075] In the system for producing methane by biomass pyrolysis gasification provided by the present utility model, the hydrogen of the first fluidizing gas inlet 3 of the riser reactor 1 and the second fluidizing gas inlet 16 of the bubbling fluidized bed reactor 2 can both be sourced from a hydrogen production device outside the system boundary (such as a water electrolysis hydrogen production device using renewable energy for power generation), or from the hydrogen-rich gas separated and purified within the system.

[0076] In the system for producing methane by biomass pyrolysis gasification provided by the present utility model, the second gas-solid separator 23 includes a raw syngas inlet 22 containing gasified semi-coke, a raw syngas outlet 24, and a gasified semi-coke outlet 25. The gasified semi-coke outlet 25 is communicated with the gasified semi-coke inlet 18 through a second gas-solid separator downcomer 26. The second gas-solid separator 23 includes one or more inertial or cyclone separators; the total separation efficiency range of the second gas-solid separator 23 is 95-99%, and dp50 is 10-30 microns.

[0077] In the system for producing methane by biomass pyrolysis gasification provided by the present utility model, the outlet 24 of the raw syngas is sequentially communicated with a waste heat recovery unit, a dust removal unit, a syngas washing unit, a carbon monoxide shift unit and a methane unit.

[0078] The working process of the system for producing methane by biomass pyrolysis gasification of the present utility model is as follows:

[0079] The biomass raw material first enters the material mixing zone 102 of the riser reactor 1 and is fully mixed with the high-temperature solid heat carrier from the bubbling fluidized bed under the action of the fluidizing gas from the gas chamber 101 of the riser reactor and passing through the first gas distributor 5, and a rapid pyrolysis reaction occurs to generate pyrolysis products (including pyrolysis gas rich in oil products and pyrolytic char). These pyrolysis products enter the first gas-solid separator 9 after passing through the rapid lifting zone 103 of the riser reactor 1. The function of the rapid lifting zone 103 is to shorten the residence time of the pyrolytic char in the reactor and prevent the reduction of the gasification activity of the char. The gas outlet temperature of the first gas-solid separator 9 is 500 - 600 °C, and the pressure is 3.0 - 7.0 MPaG. The pyrolysis gas rich in oil products flows out from the pyrolysis gas outlet 10 rich in oil products and undergoes the next pyrolysis gas washing treatment. After separating the oil products, a part is returned to the bottom of the riser, and the other part enters the carbon monoxide conversion device. For specific treatment, refer to the part of the method for producing methane by biomass pyrolysis gasification. The separated pyrolytic char enters the dense reaction zone 202 of the bubbling fluidized bed through the pyrolytic char outlet 11 of the first gas-solid separator 9 via the first gas-solid separator downcomer 12. The pyrolytic char is fully mixed with hydrogen, water vapor from the gas chamber and passing through the second gas distributor 15, and oxygen and steam at the nozzle outlet in the bubbling fluidized bed reactor 2 and undergoes intense chemical reactions. Among many chemical reactions, the main reactions are the exothermic reaction of carbon and hydrogen in the dense reaction zone 202 to generate methane, and the endothermic reaction of carbon and water vapor to generate hydrogen and carbon monoxide; the exothermic reaction of water vapor and carbon monoxide in the dilute phase reaction zone 203 to generate hydrogen and carbon dioxide. The generated raw syngas mainly contains methane, hydrogen, carbon monoxide, carbon dioxide, etc. Part of the gasified char will enter the second gas-solid separator 23 along with the raw syngas. The gas outlet temperature of the second gas-solid separator 23 is 800 - 900 °C, and the pressure is 3.0 - 7.0 MPaG. The separated gasified char returns to the dense reaction zone 202 of the bubbling fluidized bed through the gasified char outlet 25 of the second gas-solid separator 23 via the second gas-solid separator downcomer 26. Part of the gasification slag is discharged from the gasifier through the slag outlet on the side wall of the dense reaction zone 202 of the bubbling fluidized bed, and the other part of the slag and the inert bed material enter the riser reactor 1 as the heat source for the biomass hydro-pyrolysis reaction through the solid heat carrier inlet 6. The raw syngas rich in methane at the gas outlet of the second gas-solid separator 23 enters the waste heat recovery unit, dust removal unit, syngas washing unit, carbon monoxide conversion unit and methane unit for subsequent treatment. Specifically, after passing through the waste heat recovery, dust removal and washing devices, the raw syngas rich in methane is mixed with part of the pyrolysis gas generated during the biomass hydro-pyrolysis process and enters the carbon monoxide conversion device to generate a mixed gas (converted gas) mainly containing hydrogen, carbon monoxide, methane and carbon dioxide. After the mixed gas is purified by removing carbon dioxide and impurities, it enters the methanation device to produce methane.

[0080] Example 1

[0081] Pilot-scale test. 5 tons / h of biomass raw materials enter the riser reactor. Industrial analysis indicators of the biomass raw materials: moisture 11.70 wt%, ash 7.85 wt%, volatile matter 65.00%, fixed carbon 15.45%.

[0082] S1: Hydrogen (hydrogen volume 100 Nm 3 / h) is introduced into the first fluidizing gas inlet 3 of the riser reactor 1. The above-mentioned biomass raw materials first enter the material mixing zone 102 of the riser reactor 1 and are fully mixed with the high-temperature solid heat carrier from the bubbling fluidized bed under the action of hydrogen and recycled pyrolysis gas from the riser reactor gas chamber 101 and passing through the first gas distribution plate 5 (the mass ratio of the solid heat carrier to the biomass raw material entering the furnace is 3), and a rapid hydro-pyrolysis reaction occurs to generate pyrolysis products. After passing through the rapid lifting zone 103 of the riser reactor 1, the pyrolysis products enter the first gas-solid separator 9. The first gas-solid separator 9 separates gas and solid to obtain 1191 Nm 3 / h of pyrolysis gas rich in oil products (dry gas volume of pyrolysis gas after deducting carrier gas from the product gas at the riser outlet) and 1815 kg / h of pyrolysis semi-coke. Among them, the gas velocity in the rapid lifting zone is 2.25 m / s, the height is 11.2 m, the diameter of the rapid lifting zone is 0.26 m. The superficial gas velocity of the rapid lifting zone 103 is 2.25 times that of the material mixing zone 102, the height ratio of the rapid lifting zone 103 to the material mixing zone 102 is 11.2, and the material mixing zone 102 is 1.15 times the diameter of the rapid lifting zone 103; the pressure at the rich oil product pyrolysis gas outlet 10 of the first gas-solid separator 9 is 3.0 MPaG, and the temperature is 600 °C. The volume percentages of methane, hydrogen, carbon monoxide, and carbon dioxide in the pyrolysis gas rich in oil products are CH4 21%, H2 11%, CO 32%, and CO2 35% respectively.

[0083] S2: The pyrolysis gas rich in oil products flows out from the rich oil product pyrolysis gas outlet 10 and undergoes pyrolysis gas washing treatment. After separating the oil products, 3976 Nm 3 / h of pyrolysis gas, a part of it returns to the first fluidizing gas inlet 3 at the bottom of the riser, and the molar ratio of the pyrolysis gas returning to the lower part of the riser reactor to the outlet gas of the riser reactor is 70 mol%; another part of the pyrolysis gas enters the carbon monoxide conversion device.

[0084] S3: The 1815 kg / h of pyrolysis semicoke in Step S1 enters the dense reaction zone 202 of the bubbling fluidized bed through the pyrolysis semicoke outlet 11 of the first gas-solid separator 9 via the first gas-solid separator feed pipe 12. The pyrolysis semicoke is fully mixed with hydrogen, water vapor from the gas chamber and passing through the second gas distribution plate 15, as well as oxygen and steam from the nozzle outlet in the bubbling fluidized bed reactor 2, and undergoes a violent chemical reaction to obtain raw syngas containing gasified semicoke and slag. The inner diameter of the pressurized fluidized bed reactor is 0.5 m and the height is 12 m. Among them, the steam flow rate at the bottom inlet of the bubbling fluidized bed is 1.15 kg / h, the inlet hydrogen flow rate is 895 Nm 3 / h, and the inlet oxygen flow rate (O2 purity 99.6 vol%) is 274 Nm 3 / h. The solid particle density in the dense reaction zone 202 is 1600 kg / m 3 , the fluidization density is 600 kg / m 3 , the solid particle density in the dilute reaction zone 203 is 400 kg / m 3 , the solid content in the gas in the dilute reaction zone 203 is 50 kg / m 3 , the height of the dilute reaction zone 203 is 8 m, and the height ratio of the dilute reaction zone 203 to the dense reaction zone 202 is 2; 90 kg / h of slag is discharged, 30 kg / h of slag and inert bed material are returned to the riser reactor described in Step S1 as solid heat carriers. The ratio of solid heat carrier to biomass feedstock into the furnace is 3. The raw syngas containing gasified semicoke is separated by the second gas-solid separator 23 to obtain syngas and gasified semicoke; the outlet pressure of the raw syngas outlet 24 is 3.0 MPaG and the temperature is 900 °C; the volume ratio of syngas (raw syngas outlet 24) to pyrolysis gas (pyrolysis gas outlet 10) is 0.95 vol / vol. The product gas (dry gas) output at the outlet of the fluidized bed reactor is 2673 Nm 3 / h. The volume percentages of methane, hydrogen, carbon monoxide, and carbon dioxide in the syngas are 26% for CH4, 31% for H2, 18% for CO, and 24% for CO2 respectively.

[0085] S4: The methane-rich raw syngas from the gas outlet of the second gas-solid separator 23 sequentially enters a waste heat recovery unit, a dust removal unit, a syngas scrubbing unit, a carbon monoxide conversion unit, a syngas purification and methanation unit for subsequent treatment. After the raw syngas is cooled to 220 °C in the waste heat recovery unit, solid particles larger than 5 microns in the raw syngas are removed in the dust removal unit, and then it enters the scrubbing unit to remove the remaining solid particles and other harmful impurities in the raw syngas, such as HCl, NH3, HCN, etc. In the carbon monoxide conversion unit, part of the CO in part of the raw syngas is converted into H2, so that the ratio of H2:CO in the syngas at the outlet of the conversion unit is 3 mol / mol. The converted syngas is purified in the purification unit to remove impurities such as COS and H2S as well as CO2, and then enters the methanation unit to convert CO and H2 in the syngas into CH4. (Methane production is 1300 Nm 3 / h)

[0086] Outlet product distribution: Oil production is 1250 kg / h (40 wt% monocyclic aromatics, 20% phenols, and the rest are other polycyclic and aliphatic compounds). The raw syngas at the outlet of the bubbling fluidized bed reactor does not contain tar. The dry gas volume of the washed pyrolysis gas obtained in step S2 and the washed gasified syngas obtained in step S4 after mixing is 3800 Nm 3 / h, (entering the carbon monoxide conversion together), in which CH4: 25 vol%, H2: 26 vol%, CO: 21 vol%, CO2: 27 vol%. The slag discharge amount of the fluidized bed reactor is 90 kg / h (slag outlet 20), the carbon content in the slag is 1.5%, the fly ash amount is 181 kg / h (syngas dust removal), and the cold gas efficiency of the conversion of biomass raw materials in the riser and the fluidized bed reactor (definition: (calorific value of the mixed gas + calorific value of the oil product) / (calorific value of the biomass raw material + calorific value of the inlet hydrogen)) is 88%. The carbon conversion rate is 98.0% (definition: 1 - (carbon content in the fly ash + carbon content in the slag) / (carbon content in the biomass raw material))

[0087] A system for producing methane by biomass pyrolysis gasification proposed by the present utility model has been described through preferred embodiments. It is obvious to those skilled in the relevant art that the process methods described herein can be modified or appropriately changed and combined without departing from the content, spirit, and scope of the present utility model to implement the technology of the present utility model. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they will all be regarded as being included in the spirit, scope, and content of the present utility model.

Claims

1. A system for producing methane by pyrolysis gasification of biomass, characterized in that, It includes a riser reactor (1), a first gas-solid separator (9), a bubbling fluidized bed reactor (2) and a second gas-solid separator (23). The riser reactor (1) includes a biomass raw material inlet (4), a solid heat carrier inlet (6), a pyrolysis product outlet (7), and a first fluidizing gas inlet (3); the first gas-solid separator (9) includes a pyrolysis product inlet (8), a pyrolysis gas outlet (10) rich in oil products, and a pyrolysis semicoke outlet (11); the bubbling fluidized bed reactor (2) includes a pyrolysis semicoke inlet (13), a raw synthesis gas outlet (21) containing gasified semicoke, a slag outlet (20), a solid heat carrier outlet (14), a second fluidizing gas inlet (16), and a gasified semicoke inlet (18); the second gas-solid separator (23) includes a raw synthesis gas inlet (22) containing gasified semicoke, a raw synthesis gas outlet (24), and a gasified semicoke outlet (25); the pyrolysis product outlet (7) is communicated with the pyrolysis product inlet (8), the pyrolysis semicoke outlet (11) is communicated with the pyrolysis semicoke inlet (13), the raw synthesis gas outlet (21) containing gasified semicoke is communicated with the raw synthesis gas inlet (22) containing gasified semicoke, the gasified semicoke outlet (25) is communicated with the gasified semicoke inlet (18), and the solid heat carrier outlet (14) is communicated with the solid heat carrier inlet (6).

2. The system for producing methane by pyrolysis gasification of biomass according to claim 1, characterized in that, The riser reactor (1) sequentially includes a riser reactor gas chamber (101), a material mixing zone (102) and a rapid lifting zone (103) from bottom to top. A first gas distribution plate (5) is provided between the riser reactor gas chamber (101) and the material reaction zone. The first fluidizing gas inlet (3) is communicated with the riser reactor gas chamber (101). The biomass raw material inlet (4) and the solid heat carrier inlet (6) are respectively communicated with the material mixing zone (102), and the pyrolysis product outlet (7) is communicated with the rapid lifting zone (103).

3. The system for producing methane by biomass pyrolysis gasification according to claim 2, wherein, The superficial gas velocity of the rapid lifting zone (103) is 1.5 - 2.5 times that of the material mixing zone (102); and / or, the height ratio of the rapid lifting zone (103) to the material mixing zone (102) is 7 - 12; and / or, the diameter ratio of the rapid lifting zone (103) to the material mixing zone (102) is 0.75 - 0.

9.

4. The system for producing methane by pyrolysis gasification of biomass according to claim 1, characterized in that, The bubbling fluidized bed reactor (2) sequentially includes a bubbling fluidized bed reactor gas chamber (201), a dense phase reaction zone (202) and a dilute phase reaction zone (203) from bottom to top. A second gas distribution plate (15) is provided between the bubbling fluidized bed reactor gas chamber (201) and the dense phase reaction zone (202). The second fluidizing gas inlet (16) is communicated with the bubbling fluidized bed reactor gas chamber (201). The pyrolysis semicoke inlet (13), the slag outlet (20), the solid heat carrier outlet (14), and the gasified semicoke inlet (18) are respectively communicated with the dense phase reaction zone (202), and the raw synthesis gas outlet (21) containing gasified semicoke is communicated with the dilute phase reaction zone (203).

5. The system for producing methane by pyrolysis gasification of biomass according to claim 4, wherein, It further includes a third fluidizing gas inlet (17), and the third fluidizing gas inlet (17) is communicated with the bubbling fluidized bed reactor gas chamber (201); and / or, gas nozzles (19) are arranged on the second gas distribution plate (15); And / or, the fluidization density of the dense-phase reaction zone (202) is 200 - 600 kg / m 3 ; And / or, the solid content of the gas in the dilute-phase reaction zone (203) is less than 50 kg / m 3 ; and / or, the height ratio of the dilute-phase reaction zone (203) to the dense-phase reaction zone (202) is 1.5 - 2.

6. The system for producing methane by biomass pyrolysis gasification according to claim 5, characterized in that, The fluidizing gas of the third fluidizing gas inlet (17) includes oxygen and water vapor.

7. The system for producing methane by biomass pyrolysis gasification according to claim 1, characterized in that, The pyrolysis semicoke outlet (11) is communicated with the pyrolysis semicoke inlet (13) through a first gas-solid separator discharge pipe (12); and / or, the gasification semicoke outlet (25) is communicated with the gasification semicoke inlet (18) through a second gas-solid separator discharge pipe (26); and / or, the solid heat carrier outlet (14) is communicated with the solid heat carrier inlet (6) through a solid heat carrier pipeline (27).

8. The system for producing methane by biomass pyrolysis gasification according to claim 1, characterized in that, The fluidizing gas of the first fluidizing gas inlet (3) is hydrogen, and the hydrogen is sourced from a hydrogen production device outside the system boundary or hydrogen-rich gas separated and purified within the system; and / or, the fluidizing gas of the second fluidizing gas inlet (16) includes hydrogen and water vapor.

9. The system for producing methane by pyrolysis gasification of biomass according to claim 8, wherein, The hydrogen of the first fluidizing gas inlet (3) is sourced from a hydrogen production device outside the system boundary or hydrogen-rich gas separated and purified within the system; and / or, the hydrogen of the second fluidizing gas inlet (16) is sourced from a hydrogen production device outside the system boundary or hydrogen-rich gas separated and purified within the system.

10. The system for producing methane by pyrolysis gasification of biomass according to claim 1, characterized in that, The raw syngas outlet (24) is successively communicated with a waste heat recovery unit, a dust removal unit, a syngas scrubbing unit, a carbon monoxide shift unit, and a methane unit.

Images