Alkali metal / chlorine capture and synergistic tar reforming system for co-gasification of biomass and plastics

Abstract

This application pertains to the field of solid waste treatment, specifically disclosing an alkali metal / chlorine-containing co-gasification tar reforming system for biomass and plastics. The system includes a gasification unit and a separation unit connected in sequence. The gasification unit co-gasifies biomass and plastics to obtain syngas, which is then fed into the separation unit. The separation unit includes a capture-catalyst system comprising a capture-compound pyrolysis zone and a catalytic product separation zone arranged sequentially along the gas flow direction. The capture-compound pyrolysis zone contains a built-in catalytic capture agent to obtain purified syngas. The catalytic product separation zone has a hydrogen channel above connected to a gas storage tank, a tail gas channel below connected to a tail gas processor, and a pyrolysis oil channel at the tail end connected to a pyrolysis oil storage tank. The catalytic product separation zone also incorporates a hydrogen separator. This application utilizes the capture-compound pyrolysis zone to achieve the co-capture of alkali metals and chlorinated acid gases, effectively solving problems such as equipment corrosion and slagging.

Description

Technical Field

[0001] This application belongs to the field of solid waste treatment, and more specifically, relates to an alkali metal / chlorine capture and synergistic tar reforming system for co-gasification of biomass and plastics. Background Technology

[0002] Biomass materials such as straw and forestry waste, seemingly useless, actually contain enormous potential value. Meanwhile, plastics like polyvinyl chloride (PVC) and polyethylene (PE), widely used in daily life and industrial production, while versatile, also face challenging disposal problems. The technology of co-pyrolyzing biomass and plastics to produce hydrogen not only efficiently treats waste, achieving resource utilization and reducing negative environmental impacts, but also produces hydrogen—a clean energy source with zero carbon emissions. Hydrogen, as a high-quality energy source, is of great significance for optimizing the energy structure and reducing carbon emissions. It is precisely because this co-pyrolysis hydrogen production technology possesses the dual advantages of waste resource utilization and low-carbon energy production that it stands out in the energy field, becoming a highly anticipated research hotspot and providing a promising technological direction and new approach for achieving the "dual carbon" goal.

[0003] However, this process faces multiple technical bottlenecks: chlorine in plastics (such as PVC with a chlorine content of up to 56%) generates acidic gases such as HCl during pyrolysis, which corrodes equipment and pipes; alkali metals (Na, K, etc.) contained in biomass and some plastics volatilize and condense at high temperatures, leading to slagging on boiler heating surfaces and reduced heat transfer efficiency; in addition, the tar (polycyclic aromatic hydrocarbons) produced by pyrolysis easily clogs pipes, reduces hydrogen purity, and increases subsequent purification costs.

[0004] Currently, pollutant control in co-pyrolysis processes mainly focuses on solving single problems, with some methods failing to address the co-pyrolysis of biomass with other materials (such as plastics). Regarding tar treatment, the effectiveness of treating tar generated from the co-pyrolysis of complex feedstocks is unsatisfactory, and research on its formation mechanism is insufficient. Some methods only focus on controlling the upstream stage of the "feedstock," neglecting the control of tar formation by the actual reactions during gasification. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides an alkali metal / chlorine capture and synergistic tar reforming system for co-gasification of biomass and plastics, aiming to solve the problem of the inability to synergistically control pollutants during the existing co-pyrolysis process of biomass and plastics.

[0006] This application provides an alkali metal / chlorine capture and synergistic tar reforming system for co-gasification of biomass and plastics, specifically comprising a gasification unit and a separation unit connected in sequence. The gasification unit is used to co-gasify biomass and plastics to obtain syngas, which is then fed into the separation unit. The separation unit includes a capture-catalyst, a gas storage tank, a tail gas processor, and a pyrolysis oil storage tank. The capture-catalyst includes a capture-complex pyrolysis zone and a catalytic product separation zone arranged sequentially along the gas flow direction. The capture-complex pyrolysis zone contains a built-in catalytic trapping agent for capturing chlorinated acid gases and alkali metals in the syngas, and separating the alkali metals and catalytic products. The catalytic product separation zone is equipped with a hydrogen separation element. The hydrogen is separated from the syngas by a hydrogen separation element and connected to a gas storage tank. A cracked oil channel is provided at the bottom of the separation zone and connected to a cracked oil storage tank. A tail gas channel is provided at the tail end and connected to a tail gas processor. The separation zone also includes a built-in hydrogen separator to separate hydrogen from the purified syngas and send it to the gas storage tank via the hydrogen channel. Simultaneously, the cracked oil from the purified syngas is sent to the cracked oil storage tank via the cracked oil channel under gravity, and the remaining tail gas is sent to the tail gas processor via the tail gas channel.

[0007] Compared with the prior art, the present application optimizes the structure of the separation unit, utilizes the capture composite pyrolysis zone to achieve the synergistic capture of alkali metals and chlorinated acid gases, and cracks the tar in the syngas under the coupling effect of alkali metals and catalytic capture agents, thereby achieving the synergistic control of pollutants in the co-pyrolysis process of biomass and plastics.

[0008] As a further preferred embodiment, the trap-catalyst further includes a gas homogenization zone, which is disposed in front of the trap-compound pyrolysis zone along the gas flow direction, for homogenizing the syngas.

[0009] As a further preferred embodiment, the gasification unit includes a feed assembly and a gasification reaction tower, wherein the feed assembly is used to supply a mixture of biomass and plastics to the gasification reaction tower; and the gasification reaction tower is used to gasify the mixture to obtain syngas.

[0010] As a further preferred embodiment, the feeding assembly includes a first crusher, a second crusher, and a mixer. The first crusher is used to crush biomass and feed it into the mixer, the second crusher is used to crush plastic and feed it into the mixer, and the mixer is connected to the inlet of the gasification reaction tower to mix the crushed biomass and plastic to obtain a mixture and feed it into the gasification reaction tower.

[0011] As a further preferred embodiment, the alkali metal / chlorine capture and synergistic tar reforming system further includes a thermal energy recovery unit, which is connected to the exhaust gas processor and is used to perform combustion treatment on the exhaust gas to recover the thermal energy in the exhaust gas.

[0012] As a further preferred embodiment, the thermal energy reuse unit includes an incinerator and a heat exchanger connected in sequence. The incinerator is connected to a tail gas processor for introducing tail gas for combustion treatment and sending heat to the heat exchanger. The heat exchanger is connected to a gasification reaction tower to use the heat generated by the combustion of tail gas to heat the gasification reaction.

[0013] As a further preferred embodiment, the incinerator is also connected to a pyrolysis oil storage tank to utilize the heat generated by the combustion of the pyrolysis oil to heat the gasification reaction.

[0014] As a further preferred embodiment, the hydrogen separation element in the catalytic product separation zone is a pressure swing adsorption element or a hydrogen separation membrane.

[0015] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages: 1. The alkali metal / chlorine capture and synergistic tar reforming system for biomass and plastic co-gasification provided in this application optimizes the structure of the separation unit and utilizes the capture composite pyrolysis zone to achieve synergistic capture of alkali metals and chlorine-containing acidic gases, effectively solving problems such as equipment corrosion and slagging. At the same time, under the coupling effect of alkali metals and catalytic capture agents, the tar in the syngas is cracked and decomposed into small molecules, thereby effectively solving the problem of tar clogging the pipeline, and thus achieving synergistic control of pollutants during the co-pyrolysis of biomass and plastics. 2. At the same time, by setting up a thermal energy recycling unit, this application can effectively realize the recovery and utilization of thermal energy in the exhaust gas, and further improve energy utilization efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the alkali metal / chlorine capture and synergistic tar reforming system for co-gasification of biomass and plastics provided in the embodiments of this application; Figure 2 This is a cross-sectional view of the trap-catalyst in the alkali metal / chlorine trapping synergistic tar reforming system for biomass and plastic co-gasification provided in the embodiments of this application.

[0017] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-First pulverizer, 2-Second pulverizer, 3-Agitator, 4-Gasification reaction tower, 5-Catalyst-Catcher, 51-Gas homogenization zone, 52-Catalyst-Cyclic pyrolysis zone, 53-Catalyst product separation zone, 54-Tail gas channel, 55-Hydrogen channel, 56-Cracked oil channel, 6-Gasification storage tank, 7-Tail gas processor, 8-Cracked oil storage tank, 9-Incinerator, 10-Heat exchanger. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0019] like Figure 1 , 2 As shown, this application provides an alkali metal / chlorine capture and co-processing tar reforming system for co-gasification of biomass and plastics, specifically comprising a gasification unit and a separation unit connected in sequence, wherein: The gasification unit is used to co-gasify biomass and plastics to obtain syngas, which is then fed into the separation unit. The syngas includes hydrogen, chlorinated acid gases, alkali metal vapors, and tar. Plastics are used as a high-quality hydrogen feedstock for gasification, and the generation of chlorinated acid gases is effectively controlled through synergistic pyrolysis with biomass. The separation unit includes a trap-catalyst 5, a gas storage tank 6, a tail gas processor 7, and a pyrolysis oil storage tank 8. The trap-catalyst 5 includes a trapping composite pyrolysis zone 52 and a catalytic product separation zone 53 arranged sequentially along the gas flow direction. The trapping composite pyrolysis zone 52 contains a built-in catalytic trapping agent to trap chlorinated acid gases and alkali metals in the syngas. Under the coupling effect of alkali metals and catalytic trapping agent, the tar in the syngas is cracked, thereby obtaining purified syngas. Through the synergistic purification system formed by the trapping composite pyrolysis zone 52, alkali metals and chlorinated acid gases can be efficiently trapped, effectively solving problems such as equipment corrosion and slagging. At the same time, it can give full play to the catalytic effect of alkali metals on tar decomposition, effectively solving tar blockage. To address issues such as blockage and low yield, the catalyst product separation zone 53 has a hydrogen channel 55 at the top connected to a gas storage tank 6, a cracked oil channel 56 at the bottom connected to a cracked oil storage tank 8, and a tail gas channel 54 at the tail end connected to a tail gas processor 7. The catalyst product separation zone 53 also incorporates a hydrogen separation element (such as a pressure swing adsorption element or a hydrogen separation membrane) to separate hydrogen from the purified synthesis gas and send it to the gas storage tank 6 through the hydrogen channel 55. Simultaneously, the cracked oil from the purified synthesis gas is sent to the cracked oil storage tank 8 through the cracked oil channel 56 under gravity, and the remaining tail gas is sent to the tail gas processor 7 through the tail gas channel 54 to further remove residual trace impurities (such as dust).

[0020] This application optimizes the structure of the separation unit, utilizes a capture-composite pyrolysis zone to achieve synergistic capture of alkali metals and chlorinated acid gases, and cracks tar in the syngas under the coupling effect of alkali metals and catalytic capture agents. The resulting synergistic purification system achieves synergistic control of pollutants during the co-pyrolysis of biomass and plastics, effectively solving problems such as equipment corrosion, slagging, and pipeline blockage. At the same time, it increases hydrogen yield and reduces production costs, demonstrating significant economic and environmental benefits. It provides an efficient technical solution for the resource utilization of biomass and plastic waste and the production of low-carbon hydrogen energy.

[0021] Furthermore, the capture-catalyst 5 also includes a gas homogenization zone 51, which is located in front of the capture composite cracking zone 52 along the gas flow direction. It is used to homogenize the syngas, so that the hydrogen, chlorinated acid gas, alkali metal vapor and tar in the syngas are mixed evenly, which is beneficial to subsequent processes.

[0022] Furthermore, the gasification unit includes a feeding assembly and a gasification reaction tower 4. The feeding assembly is used to supply a mixture of biomass and plastics to the gasification reaction tower 4, specifically including a first crusher 1, a second crusher 2, and a mixer 3. The first crusher 1 is used to crush the biomass and feed it into the mixer 3. The second crusher 2 is used to crush the plastics and feed them into the mixer 3. The mixer 3 is connected to the inlet of the gasification reaction tower 4 and is used to mix the crushed biomass and plastics in a certain proportion to obtain a mixture and feed it into the gasification reaction tower 4. The gasification reaction tower 4 is used to gasify the mixture to obtain syngas.

[0023] Furthermore, the alkali metal / chlorine capture and synergistic tar reforming system also includes a thermal energy recovery unit. The thermal energy recovery unit is connected to the exhaust gas processor 7 and is used to combust the exhaust gas to recover the thermal energy in the exhaust gas. Specifically, it includes an incinerator 9 and a heat exchanger 10 connected in sequence. The incinerator 9 is connected to the exhaust gas processor 7 and is used to introduce the exhaust gas for combustion and send the heat to the heat exchanger 10. The heat exchanger 10 is connected to the gasification reaction tower 4 to use the heat generated by the combustion of the exhaust gas to heat the gasification reaction.

[0024] Furthermore, the incinerator 9 is also connected to the pyrolysis oil storage tank 8 to use the heat generated by the combustion of the pyrolysis oil to heat the gasification reaction.

[0025] The workflow of the biomass and plastic co-gasification alkali metal / chlorine capture and synergistic tar reforming system provided in this application is as follows: Biomass is fed into the first crusher 1 for crushing to a particle size of 20-50mm, while plastic is fed into the second crusher 2 for crushing to a particle size of 10-30mm. The crushed biomass and crushed plastic are then fed into a mixer 3 at a certain mass ratio and stirred for 10-15 minutes to ensure that the two materials are mixed evenly, thus obtaining a mixture. The mixed materials are fed into the gasification reaction tower 4 through the feeder. The gasification reaction tower 4 is started and the temperature and pressure inside the tower are controlled to carry out a co-gasification reaction to generate syngas containing H2, CO, CH4, chlorinated acid gases (such as HCl), alkali metal (Na, K) vapors and tar. Syngas generated in gasification reactor 4 is piped into capture-catalyst 5. First, the gas composition is kept uniform in the gas homogenization zone 51. Then, in the capture and composite cracking zone, the chlorinated acid gas and alkali metal in the syngas are adsorbed and captured by the catalytic capture agent. At the same time, the tar is catalytically cracked into small molecule carbides and cracked oil by the coupling effect of alkali metal and catalytic capture agent, thereby obtaining purified syngas and sending it into the catalytic product separation zone 53. The purified syngas is separated into hydrogen by a hydrogen separator and sent to the gas storage tank 6 through the hydrogen channel 55. At the same time, the cracked oil in the purified syngas is sent to the cracked oil storage tank 8 through the cracked oil channel 56 under gravity. Part of the remaining tail gas is sent to the tail gas processor 7 through the tail gas channel 54, and the other part is sent to the incinerator 9 for combustion. The cracked oil in the cracked oil storage tank 8 can also be sent to the incinerator 9 for combustion, and the heat generated is sent to the gasification reaction tower 4 through the heat exchanger 10. In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0026] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A biomass and plastic co-gasification alkali metal / chlorine capture and synergistic tar reforming system, characterized in that, The system includes a gasification unit and a separation unit connected in sequence. The gasification unit is used to co-gasify biomass and plastics to obtain syngas, which is then fed into the separation unit. The separation unit includes a trap-catalyst (5), a gas storage tank (6), a tail gas processor (7), and a pyrolysis oil storage tank (8). The trap-catalyst (5) includes a trap-complex pyrolysis zone (52) and a catalytic product separation zone (53) arranged in sequence along the gas flow direction. The trap-complex pyrolysis zone (52) contains a built-in catalytic trapping agent, which is used to trap chlorinated acid gases and alkali metals in the syngas. Under the coupling effect of alkali metals and catalytic trapping agent, the tar in the syngas is cracked, thereby obtaining purified syngas. The catalyst product separation zone (53) has a hydrogen channel (55) above it and is connected to the gas storage tank (6), a cracked oil channel (56) below it and is connected to the cracked oil storage tank (8), and a tail gas channel (54) at the tail end and is connected to the tail gas processor (7). The catalyst product separation zone (53) is equipped with a hydrogen separator to separate the hydrogen in the purified synthesis gas and send it into the gas storage tank (6) through the hydrogen channel (55). At the same time, the cracked oil in the purified synthesis gas is sent into the cracked oil storage tank (8) through the cracked oil channel (56) under the action of gravity, and the remaining tail gas is sent into the tail gas processor (7) through the tail gas channel (54).

2. The alkali metal / chlorine capture and synergistic tar reforming system for co-gasification of biomass and plastics as described in claim 1, characterized in that, The trap-catalyst (5) further includes a gas homogenization zone (51), which is located in front of the trap-composite cracking zone (52) along the gas flow direction and is used to homogenize the syngas.

3. The alkali metal / chlorine capture and synergistic tar reforming system for co-gasification of biomass and plastics as described in claim 1, characterized in that, The gasification unit includes a feed assembly and a gasification reaction tower (4). The feed assembly is used to supply a mixture of biomass and plastics to the gasification reaction tower (4). The gasification reaction tower (4) is used to gasify the mixture to obtain syngas.

4. The alkali metal / chlorine capture and synergistic tar reforming system for co-gasification of biomass and plastics as described in claim 3, characterized in that, The feeding assembly includes a first crusher (1), a second crusher (2) and a mixer (3). The first crusher (1) is used to crush biomass and feed it into the mixer (3). The second crusher (2) is used to crush plastic and feed it into the mixer (3). The mixer (3) is connected to the inlet of the gasification reaction tower (4) and is used to mix the crushed biomass and plastic to obtain a mixture and feed it into the gasification reaction tower (4).

5. The alkali metal / chlorine capture and synergistic tar reforming system for co-gasification of biomass and plastics as described in claim 1, characterized in that, The alkali metal / chlorine capture and synergistic tar reforming system also includes a thermal energy recovery unit, which is connected to the exhaust gas processor (7) and is used to perform combustion treatment on the exhaust gas to recover the thermal energy in the exhaust gas.

6. The alkali metal / chlorine capture and synergistic tar reforming system for co-gasification of biomass and plastics as described in claim 5, characterized in that, The thermal energy reuse unit includes an incinerator (9) and a heat exchanger (10) connected in sequence. The incinerator (9) is connected to the exhaust gas processor (7) for introducing exhaust gas for combustion treatment and sending heat to the heat exchanger (10). The heat exchanger (10) is connected to the gasification reaction tower (4) to use the heat generated by the combustion of exhaust gas to heat the gasification reaction.

7. The alkali metal / chlorine capture and synergistic tar reforming system for co-gasification of biomass and plastics as described in claim 6, characterized in that, The incinerator (9) is also connected to the pyrolysis oil storage tank (8) to use the heat generated by the combustion of the pyrolysis oil to heat the gasification reaction.

8. The alkali metal / chlorine capture and synergistic tar reforming system for biomass and plastic co-gasification as described in any one of claims 1 to 7, characterized in that, The hydrogen separation element in the catalytic product separation zone (53) is a pressure swing adsorption element or a hydrogen separation membrane.

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