Biomass pyrolysis gasification hydrogen production system and method

Abstract

The application discloses a biomass pyrolysis and gasification hydrogen production system and method. The hydrogen production system comprises a drying unit, a pyrolysis unit, a gasification unit, a cracking unit and a heat exchange unit. The drying unit is used for drying treatment of biomass raw materials. The pyrolysis unit is connected to the downstream of the drying unit and is used for pyrolysis treatment of the dried biomass to generate solid coke and mixed gas containing tar and pyrolysis gas. The gasification unit is connected to the downstream of the pyrolysis unit and is used for gasification treatment of the generated solid coke to generate synthesis gas. The cracking unit is connected to the downstream of the pyrolysis unit and the gasification unit and is used for cracking treatment of the mixed gas and the synthesis gas to generate hydrogen-rich gas. The heat exchange unit is connected to the downstream of the cracking unit and is used for heat exchange of the generated hydrogen-rich gas.

Description

Technical Field

[0001] This invention relates to the field of biomass gasification equipment technology, specifically to a biomass pyrolysis gasification hydrogen production system and method. Background Technology

[0002] With the increasing global demand for clean energy, hydrogen energy is considered an ideal energy carrier due to its advantages such as producing only water as a combustion product, being pollution-free, and having a high calorific value. Currently, industrial hydrogen production mainly relies on fossil fuel reforming (such as natural gas reforming, oil reforming, and coal gasification), but these processes emit large amounts of CO2 and NO. x and SO x Pollutants such as carbon dioxide and fossil fuels are increasingly depleted. Therefore, developing renewable and low-carbon hydrogen production pathways has become a research hotspot. Biomass, as a carbon-neutral and abundant renewable resource, has broad prospects for hydrogen production through thermochemical conversion (such as gasification, carbonization, and reforming). However, biomass gasification for hydrogen production still faces challenges such as low hydrogen yield, tar generated during gasification clogging equipment, and insufficient gas separation and purification efficiency.

[0003] To address the aforementioned technical challenges, researchers have proposed several solutions. For example, Chinese invention patent CN114180521B, which discloses a "biomass hydrogen production system and method," uses pyrolysis, gasification, and pressure swing adsorption to produce hydrogen. Both the catalyst and adsorbent are derived from biomass raw materials. The advantage of this method is that the entire hydrogen production process relies almost entirely on biomass resources, without depending on non-renewable metal catalysts, making it environmentally friendly. Another example is Chinese invention patent CN114437833B, which discloses a "biomass hydrogen production method and system." This proposes a carbonization-gasification combined process, first carbonizing biomass to obtain biochar and volatiles, then mixing the biochar with an inexpensive gasification catalyst and gasifying it with steam. High-purity hydrogen is then produced through steam shift and pressure swing adsorption. As can be seen, the existing biomass hydrogen production technology routes are clear, but they are all staged processes, focusing on the processing effect of a single link, while the coupling between the various units is not tight. As a result, the existing biomass hydrogen production technology has shortcomings such as poor adaptability to raw materials, incomplete tar treatment, and low energy utilization efficiency. Summary of the Invention

[0004] To address the shortcomings of existing biomass hydrogen production technologies, this invention proposes a biomass pyrolysis gasification hydrogen production system and method. By constructing a complete process flow, it can solve the technical problems of poor raw material adaptability, incomplete tar treatment, and low energy utilization efficiency in existing technologies.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: In a first aspect, the present invention provides a biomass pyrolysis gasification hydrogen production system, comprising: The drying unit is used to dry biomass raw materials. A pyrolysis unit, connected downstream of the drying unit, is used to pyrolyze the dried biomass to produce solid coke and a mixture of tar and pyrolysis gas. A gasification unit, connected downstream of the pyrolysis unit, is used to gasify the generated solid coke to produce syngas. A pyrolysis unit, connected downstream of the pyrolysis unit and the gasification unit, is used to mix the generated mixed gas with syngas and then perform pyrolysis treatment to generate hydrogen-rich gas. A heat exchange unit is connected downstream of the pyrolysis unit to exchange heat with the generated hydrogen-rich gas. The gas after heat exchange is returned to the drying unit. The heat exchange unit is also connected between the pyrolysis unit and the pyrolysis unit to exchange heat with the flue gas generated by pyrolysis combustion. The gas after heat exchange is returned to the pyrolysis unit and the drying unit in sequence.

[0006] In some embodiments, a separation unit is further included, which is connected downstream of the drying unit for separating the dried gas-liquid mixture. The separated condensate is transported to the gasification unit, and the separated gas is transported to the pyrolysis unit.

[0007] In some embodiments, a temporary storage unit is further included, which is connected between the pyrolysis unit and the gasification unit for storing solid coke generated by the pyrolysis unit and conveying it to the gasification unit.

[0008] In some embodiments, the pyrolysis unit includes a furnace body, a first coil, and a second coil. The first coil and the second coil are arranged from top to bottom inside the furnace body along the height direction of the furnace body. The inlet of the first coil is connected to the pyrolysis unit, the outlet of the first coil is connected to the inlet of the second coil, the inlet of the second coil is also connected to the gasification unit, and the outlet of the second coil is connected to the heat exchange unit.

[0009] In some embodiments, the pyrolysis unit further includes burners, a plurality of burners are disposed on both sides of the furnace body and distributed layer by layer in the height direction of the furnace body, the burners are connected to the separation unit, and oxygen and natural gas are introduced into the burners.

[0010] In one preferred embodiment, the top of the furnace body is provided with a smoke outlet, which is connected in sequence to the pyrolysis unit and the drying unit.

[0011] In one preferred embodiment, the pyrolysis unit includes a main body and a spiral. The main body has a first space and a second space formed by a partition. The spiral is disposed in the first space and has a hollow structure with a first flue gas inlet, a first flue gas outlet, a biomass inlet, a coke outlet, and a mixed gas outlet. The first flue gas inlet is connected to the flue gas outlet, the first flue gas outlet is connected to the drying unit, the biomass inlet is connected to the drying unit, the coke outlet is connected to the gasification unit, and the mixed gas outlet is connected to the pyrolysis unit. The second space has a second flue gas inlet and a second flue gas outlet. The second flue gas inlet is connected to the flue gas outlet, and the second flue gas outlet is connected to the drying unit.

[0012] In one preferred embodiment, the pyrolysis unit further includes a first star feeder and a coke conveyor, the two ends of which are connected to the coke outlet and the gasification unit, respectively, and the first star feeder is disposed on the pipeline connecting the coke conveyor and the coke outlet.

[0013] In one preferred embodiment, the drying unit includes a bed, a conveyor, and a second star-shaped feeder. The conveyor is disposed inside the bed and is used to convey biomass raw materials. The conveyor has a carbon dioxide inlet and a carbon dioxide outlet. The carbon dioxide inlet is connected to the heat exchange unit, and the carbon dioxide outlet is connected to the separation unit. The bed has a third flue gas inlet and a third flue gas outlet. The third flue gas inlet is connected to the first flue gas outlet and the second flue gas outlet, and the third flue gas outlet is used to discharge flue gas into the atmosphere.

[0014] Secondly, the present invention also provides a method for producing hydrogen through biomass pyrolysis and gasification, based on the hydrogen production system provided in the first aspect of the present invention, wherein the hydrogen production method includes the following steps: The biomass raw materials are dried to remove moisture and volatile organic compounds. The dried biomass is pyrolyzed to produce solid coke and a mixture of tar and pyrolysis gas. The generated solid coke is gasified to produce syngas. The mixed gas is mixed with the syngas and then subjected to cracking treatment to generate hydrogen-rich gas; The generated hydrogen-rich gas undergoes heat exchange, and the gas after heat exchange is used to provide high-temperature conditions for drying, pyrolysis, and cracking.

[0015] Compared with the prior art, the beneficial effects of the present invention mainly include: This invention provides a biomass pyrolysis gasification hydrogen production system and method. By closely coupling a drying unit, a pyrolysis unit, a gasification unit, and a pyrolysis unit, the biomass feedstock undergoes a complete four-stage process of drying, pyrolysis, gasification, and pyrolysis. The drying process allows high-moisture-content wet biomass to be directly fed into the system without pre-drying, breaking the stringent requirements of traditional processes regarding feedstock moisture content. The pyrolysis and gasification processes are independent steps, allowing for adjustments to the gasifying agent flow rate and residence time for different biomass feedstocks. This distributed processing allows the system to flexibly adapt to various feedstocks, from highly reactive to low-reactivity. The high-temperature pyrolysis process forces the tar, regardless of whether it is light or heavy, into small-molecule, hydrogen-rich gas, eliminating process barriers caused by differences in tar characteristics among different feedstocks. This enables the processing of even low-quality feedstocks with high ash content and high tar yield. Therefore, this invention improves the adaptability of biomass feedstocks, expanding from traditional high-quality sawdust to straw, rice husks, fruit shells, bark, sugarcane bagasse, and even some urban organic waste. In addition, the present invention recovers the heat after pyrolysis through a heat exchange unit and uses the recovered heat for the drying, pyrolysis and pyrolysis of the system, which can significantly reduce energy consumption and external energy purchase costs, and reduce the operating costs of the system. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this application, the accompanying drawings used in the embodiments will be briefly described below: Figure 1 This is a structural block diagram of the biomass pyrolysis gasification hydrogen production system described in this invention; Figure 2 This is a schematic diagram of the drying unit described in this invention; Figure 3 This is a schematic diagram of the pyrolysis unit described in this invention; Figure 4 This is a schematic diagram of the pyrolysis unit described in this invention; Figure 5 This is a process flow diagram of the biomass pyrolysis gasification hydrogen production method described in this invention.

[0017] As shown in the figure: 100. Drying unit; 110. Bed; 111. Third flue gas inlet; 112. Third flue gas outlet; 120. Conveying body; 121. Carbon dioxide inlet; 122. Carbon dioxide outlet; 130. Second star feeder. 200. Pyrolysis unit; 210. Main body; 211. First space; 212. Second space; 2121. Second flue gas inlet; 2122. Second flue gas outlet; 220. Spiral; 221. First flue gas inlet; 222. First flue gas outlet; 223. Biomass inlet; 224. Coke outlet; 225. Mixed gas outlet; 230. First star feeder; 240. Coke conveyor; 300. Gasification unit; 400, pyrolysis unit; 410, furnace body; 411, flue gas outlet; 420, first coil; 430, second coil; 440, burner; 500, Heat exchange unit; 600, Separation Unit; 700. Temporary storage unit; 800. Fan. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] This invention addresses the technical problems of existing biomass hydrogen production technologies, which often emphasize unidirectional processes with little coupling between different steps, resulting in low process integration, narrow applicability of biomass feedstocks, low energy utilization, and high system operating costs. It proposes a biomass pyrolysis gasification hydrogen production system and method, applicable to various agricultural and forestry biomass, and characterized by a compact and rational process flow and high energy utilization.

[0020] like Figures 1-4 As shown, in a first aspect, the present invention provides a biomass pyrolysis gasification hydrogen production system, comprising a drying unit 100, a pyrolysis unit 200, a gasification unit 300, a pyrolysis unit 400, and a heat exchange unit 500. The drying unit 100 is used to dry biomass raw materials; the pyrolysis unit 200 is connected downstream of the drying unit 100 and is used to pyrolyze the dried biomass to generate solid coke and a mixed gas containing tar and pyrolysis gas; the gasification unit 300 is connected downstream of the pyrolysis unit 200 and is used to gasify the generated solid coke to generate syngas; the pyrolysis unit 400 is connected downstream of the pyrolysis unit 200 and the gasification unit 300 and is used to mix the generated mixed gas with the syngas and then perform pyrolysis to generate hydrogen-rich gas; the heat exchange unit 500 is connected downstream of the pyrolysis unit 400 and is used to exchange heat with the generated hydrogen-rich gas.

[0021] Thus, the biomass pyrolysis gasification hydrogen production system provided by this invention tightly couples drying, pyrolysis, gasification, and pyrolysis processes together, forming a complete biomass hydrogen production process line. Compared with existing technologies, it eliminates the need for pretreatment of biomass raw materials, allowing for one-stop processing directly through this system. For example, the drying unit 100 allows high-moisture-content wet biomass to be directly fed in without pre-drying, breaking the stringent requirements of traditional processes on raw material moisture content. The pyrolysis unit 200 and gasification unit 300, as independent steps, allow for adjustment of the gasifying agent flow rate and residence time for different biomass raw materials. This distributed processing allows the system to flexibly adapt to various raw materials ranging from high to low activity. The pyrolysis unit 400, regardless of whether the tar is light or heavy, forces it to be pyrolyzed into small-molecule hydrogen-rich gas, eliminating process barriers caused by differences in tar characteristics among different raw materials, enabling the processing of even low-quality raw materials with high ash content and high tar yield. Therefore, the biomass hydrogen production system provided by this invention improves the adaptability of biomass raw materials.

[0022] Meanwhile, the present invention also includes a heat exchange unit 500 connected downstream of the pyrolysis unit 400 for heat exchange with the generated hydrogen-rich gas. The gas after heat exchange is returned to the drying unit 100. The heat exchange unit 500 is also connected between the pyrolysis unit 400 and the pyrolysis unit 200 for heat exchange with the flue gas generated by pyrolysis combustion. The gas after heat exchange is returned to the pyrolysis unit 200 and the drying unit 100 in sequence. Since the generated hydrogen-rich gas has a very high temperature, after heat exchange with the heat exchange unit 500, the cooled hydrogen-rich gas is sent away and collected, while the cooled carbon dioxide gas is heated and sent to the drying unit 100 as a heat source for the drying process. Furthermore, the high-temperature flue gas generated by pyrolysis combustion is sent to the pyrolysis unit 200 and the drying unit 100 as a heat source. In this way, energy consumption and external energy purchase costs are significantly reduced, and the operating cost of the system is lowered.

[0023] In summary, the biomass pyrolysis gasification hydrogen production system provided by this invention is a highly coordinated organic whole. It achieves more tolerant treatment of biomass feedstocks, fundamental solutions to the tar problem, and efficient tiered utilization of system energy.

[0024] The following provides a detailed description of each component of the biomass pyrolysis gasification hydrogen production system provided by the present invention.

[0025] In one preferred embodiment, combined with Figure 2As shown, the drying unit 100 includes a bed 110, a conveyor 120 and a second star feeder 130. The conveyor 120 is disposed inside the bed 110, and the second star feeder 130 is disposed on the pipeline connecting the external biomass raw material storage equipment and the conveyor 120. The conveyor 120 is a screw conveyor used to transport biomass raw materials.

[0026] The conveyor 120 has a carbon dioxide inlet 121 and a carbon dioxide outlet 122. The carbon dioxide inlet 121 is connected to the heat exchange unit 500. The high-temperature carbon dioxide gas after heat exchange with the generated hydrogen-rich gas is conveyed into the conveyor 121 to dry the biomass raw material at high temperature. The carbon dioxide gas after the biomass raw material absorbs heat is discharged through the carbon dioxide outlet 122, and the dried biomass is discharged to enter the next stage pyrolysis unit 200.

[0027] Meanwhile, the bed 110 has a third flue gas inlet 111 and a third flue gas outlet 112. The third flue gas inlet 111 is connected to the first flue gas outlet 222 and the second flue gas outlet 2122 of the pyrolysis unit 200. The pyrolysis unit 200 is connected to the flue gas outlet 411 of the pyrolysis unit 400. The high-temperature flue gas generated by the combustion of the pyrolysis unit 400 is sent to the bed 110 to dry the biomass raw materials in the conveyor body 120. The cooled flue gas is discharged into the atmosphere through the third flue gas outlet 112.

[0028] In one preferred embodiment, the present invention further includes a separation unit 600 connected downstream of the drying unit 100. This separation unit 600 separates the dried gas-liquid mixture. The separated condensate is transported to the gasification unit 300 as a process feedstock for gasification, and the separated gas is transported to the pyrolysis unit 400 as one of the fuels for combustion. This further utilizes the system's own energy and helps reduce energy consumption. It is understood that the separation unit 600 can be a gas-liquid separator from the prior art.

[0029] In one preferred embodiment, combined with Figure 3As shown, the pyrolysis unit 200 includes a main body 210 and a spiral 220. The main body 210 has a first space 211 and a second space 212 formed inside by a partition. The spiral 220 is disposed in the first space 211 and has a hollow structure. This hollow structure has a first flue gas inlet 221, a first flue gas outlet 222, a biomass inlet 223, a coke outlet 224, and a mixed gas outlet 225. The first flue gas inlet 221 is connected to the flue gas outlet 411 of the pyrolysis unit 400, and the first flue gas outlet 222 is connected to the drying unit. The first space 100 is connected to the third flue gas inlet 111; the biomass inlet 223 is connected to the drying unit 100, specifically to the conveyor 120; the coke outlet 224 is connected to the gasification unit 300; and the mixed gas outlet 225 is connected to the pyrolysis unit 400. The second space 212 has a second flue gas inlet 2121 and a second flue gas outlet 2122. The second flue gas inlet 2121 is connected to the flue gas outlet 411, and the second flue gas outlet 2122 is connected to the drying unit 100, specifically to the third flue gas inlet 111.

[0030] In this embodiment, the flue gas at >900°C from the pyrolysis unit 400 is split into two streams, entering the first space 211 and the spiral 220 respectively, thus forming an indirect heating mode with inner and outer layers. The dried biomass is carried forward at a constant speed by the spiral 220 and undergoes a pyrolysis reaction under the high temperature of the flue gas. The generated mixed gas is discharged from the mixed gas outlet 225, and the coke enters the coke conveyor 240 through the first star feeder 230. CO2 gas is introduced between the first star feeder 230 and the coke conveyor 240 and a slight positive pressure of 50-200 Pa is maintained to keep the coke in an inert gas sealed state. The flue gas cools down during the process of transferring heat to the pyrolysis reaction, and the outlet flue gas temperature drops to >400°C.

[0031] The flue gas at >400°C from the spiral 220 enters the first space 211 to indirectly heat the biomass feedstock. In addition, the flue gas in the spiral 220 directly heats the biomass. Thus, the biomass is baked by the dual effects of direct and indirect heating, releasing moisture and volatiles. The dried biomass turns black to a certain extent, and the temperature of the outlet flue gas is >100°C.

[0032] In one preferred embodiment, the pyrolysis unit 200 further includes a first star feeder 230 and a coke conveyor 240. The two ends of the coke conveyor 240 are respectively connected to the coke outlet 224 and the gasification unit 300. The first star feeder 230 is disposed on the connecting pipeline between the coke conveyor 240 and the coke outlet 224.

[0033] In one preferred embodiment, a temporary storage unit 700 is further included, which is connected between the pyrolysis unit 200 and the gasification unit 300, for storing the solid coke generated by the pyrolysis unit 200 and conveying it to the gasification unit 300.

[0034] In other words, the biomass dried by the drying unit 100 enters the spiral 220, where it undergoes a pyrolysis reaction under the combined action of the high-temperature flue gas in the spiral 220 and the high-temperature flue gas in the second space 212, generating solid coke and a mixture of gaseous tar and pyrolysis gas. The solid coke is discharged from the coke outlet 224 and transported to the temporary storage unit 700 under the action of carbon dioxide, and then transported from the temporary storage unit 700 to the gasification unit 300 as raw material for the gasification reaction; the mixture of gaseous tar and pyrolysis gas is transported to the pyrolysis unit 400 for pyrolysis reaction.

[0035] In one preferred embodiment, the pyrolysis gas has the following components: CO 20±5%, H2 30±20%, CO2 5±5%, H2O 1±1%, CH4 20±10%.

[0036] In one preferred embodiment, the coke generated after pyrolysis is transported to the gasification unit 300. At the same time, the condensate separated by the separation unit 600 also enters the gasification unit 300. In addition, oxygen and steam are introduced into the gasification unit 300. These are used as raw materials to undergo a pressurized gasification reaction in the gasification unit 300 to generate ash and syngas. The syngas composition is CO 30±5%, H2 40±5%, CO2 25±5%, H2O 1±1%, CH4 5±1%, and a small amount of tar. The syngas is sent to the cracking unit 400 as a raw material to participate in the reaction, while the ash is discharged from the system.

[0037] In one preferred embodiment, the gasification unit 300 is a pressurized circulating fluidized bed, the pressure of which is controlled at 0.4 MPa to 2 MPa and the temperature at 900 to 1000 °C. One of the raw materials, steam, is saturated water vapor at 2.5 to 3 MPa, and the mass ratio of steam to O2 is maintained at 1.2 to 1.5.

[0038] In one preferred embodiment, combined with Figure 4As shown, the pyrolysis unit 400 includes a furnace body 410, a first coil 420, and a second coil 430. The first coil 420 and the second coil 430 are arranged from top to bottom inside the furnace body 410 along its height. The inlet of the first coil 420 is connected to the pyrolysis unit 200, specifically to the mixed gas outlet 225, to send the mixed gas generated by pyrolysis into the first coil 420. The outlet of the first coil 420 is connected to the inlet of the second coil 430. The inlet of the second coil 430 is also connected to the gasification unit 300. That is, the mixed gas passing through the first coil 420 mixes with the synthesis gas entering the second coil 430 and flows in the second coil 430. The outlet of the second coil 430 is connected to the heat exchange unit 500.

[0039] In this embodiment, since the tar and CH4 content in the mixed gas is higher, it enters from the first coil 420 and stays in the furnace body 410 for a longer time; while the syngas has a lower tar and CH4 content, it enters from the second coil 430 and stays in the furnace body 410 for a shorter time.

[0040] In one preferred embodiment, the pyrolysis unit 400 further includes burners 440. Multiple burners 440 are arranged on both sides of the furnace body 410 and distributed in three layers along the height of the furnace body 410. The burners 440 are connected to the separation unit 600, meaning the separated gas is transported to the pyrolysis unit 400 as one of the combustion fuels. This gas is a mixture of carbon dioxide and volatile organic compounds. In addition, oxygen and natural gas are also introduced into the burners 440 as fuel for combustion, providing high-temperature heat for pyrolysis. Thus, the combustion temperature of the furnace body 410 is maintained at >1000℃ through oxygen-enriched combustion, causing the tar and methane in the first coil 420 to undergo a high-temperature pyrolysis reaction, mainly producing CO and H2. The high-temperature flue gas generated by oxygen-enriched combustion passes through the second coil 430 and the first coil 420 before being discharged from the flue gas outlet 411. After heat exchange with oxygen, the outlet flue gas temperature drops to >900℃.

[0041] In one preferred embodiment, the top of the furnace body 410 is provided with a flue gas outlet 411, which is connected in sequence to the pyrolysis unit 200 and the drying unit 100. That is, the generated high-temperature flue gas serves as a heat source for pyrolysis and drying to provide energy for the system, thereby reducing additional energy consumption.

[0042] like Figure 5 As shown, in a second aspect, the present invention provides a method for producing hydrogen through biomass pyrolysis and gasification, implemented based on the hydrogen production system described in the first aspect of the present invention, the hydrogen production method comprising the following steps: Step S1: Dry the biomass raw material to remove moisture and volatile organic compounds. Step S2 involves pyrolyzing the dried biomass to produce solid coke and a mixture of tar and pyrolysis gas. Step S3: The generated solid coke is gasified to generate syngas; Step S4: The mixed gas is mixed with the syngas and then subjected to cracking treatment to generate hydrogen-rich gas; Step S5 involves heat exchange of the generated hydrogen-rich gas, and the gas after heat exchange is used to provide high-temperature conditions for drying, pyrolysis, and cracking.

[0043] The hydrogen production method provided by the present invention will be described in detail below through a specific embodiment.

[0044] First, the biomass feedstock, in 40-70mm pellet form, enters the conveyor 120 with CO2 gas as a protective gas. The sensible heat of the CO2 gas and flue gas is used as a heat source to remove moisture and a small amount of volatile organic compounds (VOCs) from the biomass. The flue gas is directly discharged. The CO2 gas, mixed with the removed water and VOCs, enters the separation unit 600 for gas-water separation. The condensate after separation is used as the feedstock for subsequent gasification, while the CO2 gas and VOCs are used as fuels for pyrolysis.

[0045] Secondly, the dried biomass enters the spiral 220, where the sensible heat of the flue gas generated by pyrolysis combustion serves as a heat source to cause slow pyrolysis of the biomass, producing solid coke and a mixture of gaseous tar / pyrolysis gas. The coke enters the temporary storage unit 700 and is pneumatically transported by CO2 gas into the gasification unit 300. The coke, condensate, steam, and oxygen are used as raw materials to undergo a pressurized gasification reaction in the gasification unit 300 to produce ash and syngas. The ash is discharged, while the syngas enters the subsequent pyrolysis unit 400.

[0046] Then, the mixed gas produced by pyrolysis and the syngas produced by gasification enter the furnace body 410. Specifically, the mixed gas enters the first coil 420 and the syngas enters the second coil 430. The CH4 and tar in the mixture undergo a cracking reaction to produce CO and H2. The high temperature of the cracking reaction is provided by the combustion of pure oxygen fuel. This fuel includes part of the recycled final product (hydrogen-rich gas) and O2, as well as CO2 gas and VOCs provided by the drying unit 100.

[0047] Finally, the hydrogen-rich gas enters the heat exchange unit 500 and is cooled by room-temperature CO2 gas, reducing the temperature of the hydrogen-rich gas to 400-500℃. The CO2 gas is then heated to >400℃. The final hydrogen-rich gas composition is CO 35±5%, H2 45±5%, CO2 15±5%, H2O 1±1%, CH4 1±1%, and tar <100ppm. The hydrogen-rich gas is collected as a product by the fan 800, while the high-temperature CO2 gas continues to provide heat for other processes in the system, thereby reducing energy consumption and lowering operating costs.

[0048] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A biomass pyrolysis gasification hydrogen production system, characterized in that, include: The drying unit is used to dry biomass raw materials. A pyrolysis unit, connected downstream of the drying unit, is used to pyrolyze the dried biomass to produce solid coke and a mixture of tar and pyrolysis gas. A gasification unit, connected downstream of the pyrolysis unit, is used to gasify the generated solid coke to produce syngas. A pyrolysis unit, connected downstream of the pyrolysis unit and the gasification unit, is used to mix the generated mixed gas with syngas and then perform pyrolysis treatment to generate hydrogen-rich gas. A heat exchange unit is connected downstream of the pyrolysis unit to exchange heat with the generated hydrogen-rich gas. The gas after heat exchange is returned to the drying unit. The heat exchange unit is also connected between the pyrolysis unit and the pyrolysis unit to exchange heat with the flue gas generated by pyrolysis combustion. The gas after heat exchange is returned to the pyrolysis unit and the drying unit in sequence.

2. The biomass pyrolysis gasification hydrogen production system according to claim 1, characterized in that, It also includes a separation unit connected downstream of the drying unit, which is used to separate the dried gas-liquid mixture. The separated condensate is transported to the gasification unit, and the separated gas is transported to the pyrolysis unit.

3. The biomass pyrolysis gasification hydrogen production system according to claim 1, characterized in that, It also includes a temporary storage unit, which is connected between the pyrolysis unit and the gasification unit, for storing the solid coke generated by the pyrolysis unit and transporting it to the gasification unit.

4. The biomass pyrolysis gasification hydrogen production system according to claim 2, characterized in that, The pyrolysis unit includes a furnace body, a first coil, and a second coil. The first coil and the second coil are arranged from top to bottom inside the furnace body along the height direction of the furnace body. The inlet of the first coil is connected to the pyrolysis unit, the outlet of the first coil is connected to the inlet of the second coil, the inlet of the second coil is also connected to the gasification unit, and the outlet of the second coil is connected to the heat exchange unit.

5. The biomass pyrolysis gasification hydrogen production system according to claim 4, characterized in that, The pyrolysis unit also includes burners, and multiple burners are arranged on both sides of the furnace body and distributed layer by layer according to the height of the furnace body. The burners are connected to the separation unit, and oxygen and natural gas are also introduced into the burners.

6. The biomass pyrolysis gasification hydrogen production system according to claim 5, characterized in that, The top of the furnace body is provided with a flue gas outlet, which is connected in sequence to the pyrolysis unit and the drying unit.

7. The biomass pyrolysis gasification hydrogen production system according to claim 6, characterized in that, The pyrolysis unit includes a main body and a spiral. The main body has a first space and a second space formed by a partition. The spiral is disposed in the first space and has a hollow structure with a first flue gas inlet, a first flue gas outlet, a biomass inlet, a coke outlet, and a mixed gas outlet. The first flue gas inlet is connected to the flue gas outlet, the first flue gas outlet is connected to the drying unit, the biomass inlet is connected to the drying unit, the coke outlet is connected to the gasification unit, and the mixed gas outlet is connected to the pyrolysis unit. The second space has a second flue gas inlet and a second flue gas outlet. The second flue gas inlet is connected to the flue gas outlet, and the second flue gas outlet is connected to the drying unit.

8. The biomass pyrolysis gasification hydrogen production system according to claim 7, characterized in that, The pyrolysis unit further includes a first star feeder and a coke conveyor. The two ends of the coke conveyor are respectively connected to the coke outlet and the gasification unit. The first star feeder is located on the pipeline connecting the coke conveyor and the coke outlet.

9. The biomass pyrolysis gasification hydrogen production system according to claim 7, characterized in that, The drying unit includes a bed, a conveyor, and a second star-shaped feeder. The conveyor is located inside the bed and is used to transport biomass raw materials. The conveyor has a carbon dioxide inlet and a carbon dioxide outlet. The carbon dioxide inlet is connected to the heat exchange unit, and the carbon dioxide outlet is connected to the separation unit. The bed has a third flue gas inlet and a third flue gas outlet. The third flue gas inlet is connected to the first flue gas outlet and the second flue gas outlet, and the third flue gas outlet is used to discharge flue gas into the atmosphere.

10. A method for producing hydrogen through biomass pyrolysis and gasification, implemented based on the hydrogen production system described in any one of claims 1-9, characterized in that, The hydrogen production method includes the following steps: The biomass raw materials are dried to remove moisture and volatile organic compounds. The dried biomass is pyrolyzed to produce solid coke and a mixture of tar and pyrolysis gas. The generated solid coke is gasified to produce syngas. The mixed gas is mixed with the syngas and then subjected to cracking treatment to generate hydrogen-rich gas; The generated hydrogen-rich gas undergoes heat exchange, and the gas after heat exchange is used to provide high-temperature conditions for drying, pyrolysis, and cracking.

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