System for producing high-quality synthesis gas from household waste and carbon dioxide

Abstract

System for producing high-quality synthesis gas from household waste and carbon dioxide, characterized in that it comprises: a feeder (1), a dryer (2), a low-temperature pyrolysis reactor (3), a medium-temperature pyrolysis reactor (4) and a high-temperature pyrolysis reactor (5) connected in series; wherein the pyrolysis gas outlets of the low-temperature pyrolysis reactor (3) and the medium-temperature pyrolysis reactor (4) are successively connected to a dechlorination device (9) and a combustion chamber (8); wherein the flue gas outlet of the combustion chamber (8) is successively connected to the flue gas lines of the high-temperature pyrolysis reactor (5), the medium-temperature pyrolysis reactor (4) and the low-temperature pyrolysis reactor (3) as well as to the flue gas cleaner (10); The synthesis gas outlet of the high-temperature pyrolysis reactor (5) is successively connected to a heat exchanger (7) and a dryer (2).

Description

Technical area

[0001] The present utility model belongs to the fields of waste treatment, energy recovery and resource utilization, in particular to a pyrolysis recovery technology for household waste, and relates to a system for producing high-quality synthesis gas from household waste and carbon dioxide. Background technology

[0002] With socioeconomic development and rising living standards, the amount of household waste continues to increase, and its composition is becoming increasingly complex, significantly hindering sustainable urban development. Household waste currently contains a large quantity of materials, including discarded cardboard, plastics, rubber waste, textiles, synthetic leather, and other complex components, making direct recycling as resources difficult. The efficient, environmentally sound, and economical disposal of household waste has therefore become a central focus of waste management technology.

[0003] Existing methods of household waste disposal are primarily based on landfilling, incineration, and biological treatment. While landfilling is relatively inexpensive, it presents numerous challenges, including large land use, resource waste, leachate pollution, and greenhouse gas emissions, making compliance with environmental standards increasingly difficult. Incineration can rapidly reduce waste, but household waste with complex compositions and high concentrations of pollutants such as chlorine can easily generate hazardous substances like dioxins, and energy recovery rates are low. Biological treatment, however, is limited by the complex composition of waste and its restricted scope, and therefore cannot provide comprehensive household waste management on its own.

[0004] To address these problems, pyrolysis and gasification technologies have gained significant attention in recent years as treatment methods offering advantages in terms of waste reduction, safety, and resource utilization. The pyrolysis process converts household waste into combustible gases, tar, and charcoal under anaerobic or anoxic conditions, thus offering considerable potential for resource recovery.However, existing pyrolysis technology still has certain shortcomings when applied to household waste treatment, such as the lack of adequate temperature control in zones during the pyrolysis process, which leads to an unstable product composition; the chlorine-containing components in the waste are released in a disordered manner, increasing the effort required for gas purification; the high-temperature gasification and combustion units are not highly integrated, and the utilization efficiency of thermal energy and gas resources is limited.

[0005] Chlorides in household waste originate primarily from chlorine-containing plastics, textile waste, and paper products. Relevant literature indicates that these chlorine-containing substances begin to decompose and release chlorine during pyrolysis at temperatures between 350 °C and 420 °C. The longer the temperature is maintained at 380 °C to 420 °C, the more effective the complete chlorine release from the household waste. Chlorine removal during the pyrolysis of household waste is particularly important because effective chlorine removal can significantly reduce hydrogen chloride emissions, minimize corrosion of equipment during subsequent incineration or gasification, and prevent the formation of highly toxic pollutants such as dioxins, thereby improving exhaust gas purity.Reducing the chloride content during the treatment of household waste can also improve the quality of the gasification synthesis gas and lower the costs of post-treatment. Content of the utility model

[0006] In response to the problems of existing technology, the present utility model offers a system for producing high-quality synthesis gas from household waste and carbon dioxide, whereby this pyrolysis system for household waste does not require an external heat source and is able to effectively solve the problem of heat supply in conventional pyrolysis technologies and maximize the economic efficiency and resource utilization of household waste treatment.

[0007] The present utility model is achieved through the following technical solutions: A system for producing high-quality synthesis gas from household waste and carbon dioxide, comprising: a feeder, a dryer, a low-temperature pyrolysis reactor, a medium-temperature pyrolysis reactor and a high-temperature pyrolysis reactor connected in series; wherein the pyrolysis gas outlets of the low-temperature pyrolysis reactor and the medium-temperature pyrolysis reactor are successively connected to a dechlorination device and a combustion chamber; wherein the flue gas outlet of the combustion chamber is successively connected to the flue gas lines of the high-temperature pyrolysis reactor, the medium-temperature pyrolysis reactor and the low-temperature pyrolysis reactor as well as to the flue gas cleaner; wherein the synthesis gas outlet of the high-temperature pyrolysis reactor is successively connected to a heat exchanger and a dryer.

[0008] Preferably, the dryer, the low-temperature pyrolysis reactor, the medium-temperature pyrolysis reactor and the high-temperature pyrolysis reactor each adopt a two-chamber structure comprising an inner chamber and an outer chamber, wherein the inner chamber is provided with a material guide plate and the outer chamber with a flue gas guide vane, and each reactor forms a flue gas circuit with the combustion chamber via the heat exchanger.

[0009] Preferably, the operating temperature of the dryer is between 105 and 150 °C; The operating temperature of the low-temperature pyrolysis reactor is 150 to 450 °C and the material residence time is 30 to 80 minutes; The operating temperature of the medium-temperature pyrolysis reactor is 450 to 600 °C and the material residence time is 20 to 40 minutes; The operating temperature of the high-temperature pyrolysis reactor is 600 to 1000 °C and the material residence time is 10 to 30 minutes.

[0010] Preferably, a first induced draft fan is provided on the pipeline between the heat exchanger and the dryer.

[0011] Preferably, a valve is provided on the carbon dioxide inlet line of the high-temperature pyrolysis reactor.

[0012] Preferably, a second induced draft fan is provided on the discharge pipe of the flue gas cleaner.

[0013] Preferably, a sealing device is provided at the dryer inlet. Preferably, the dryer, the low-temperature pyrolysis reactor, the medium-temperature pyrolysis reactor, and the high-temperature pyrolysis reactor are each equipped with a PLC control unit and an automated setting module, wherein closed-loop control of temperature, flue gas flow, and material residence time of each zone is achieved via temperature sensors, flow meters, and online detectors for hydrogen chloride and hydrogen sulfide. Preferably, the dechlorination device is equipped with an absorbent spiral feed system and a mixing reaction chamber, and calcium hydroxide dry powder is used as the absorbent.

[0014] The process for producing high-quality synthesis gas from household waste and carbon dioxide includes the following steps: Feeding household waste into a dryer via a feeder, where moisture is removed at 105 to 150 °C to produce a dry material;

[0015] The dry material is successively introduced into a low-temperature pyrolysis reactor, a medium-temperature pyrolysis reactor, and a high-temperature pyrolysis reactor, where a multi-stage pyrolysis and gasification reaction takes place; the pyrolysis gas produced during the multi-stage pyrolysis is dechlorinated in a dechlorination plant and subsequently introduced into a combustion chamber for combustion, whereby the high-temperature flue gas produced during combustion flows successively through the high-temperature pyrolysis reactor, the medium-temperature pyrolysis reactor, and the low-temperature pyrolysis reactor, where an indirect heat exchange provides the heat required for the pyrolysis, and the flue gas is subsequently discharged after treatment in a flue gas cleaner.

[0016] The carbon dioxide is introduced into the high-temperature pyrolysis reactor to react with the medium-temperature coal and produce synthesis gas. The synthesis gas then enters a dryer after cooling through a heat exchanger to dry the household waste and ultimately produce high-quality synthesis gas.

[0017] Compared to the prior art, the present utility model has the following advantageous technical effects: 1) The system and process provided in the present utility model can effectively improve the pyrolysis efficiency of household waste, and the precise design of multi-stage heat exchange zones allows targeted pyrolysis and gasification reactions to be carried out at different temperatures, thereby improving the resource utilization efficiency of household waste. Each temperature zone controls and optimizes the pyrolysis and gasification reaction temperatures of household waste, thus improving the conversion efficiency of gasification to synthesis gas. 2) The system and process provided in this utility model enable the efficient recycling of household waste and reduce energy consumption: Pyrolysis oil and gas produced in the low-temperature and medium-temperature zones are dechlorinated before entering the combustion chamber, so that the resulting high-temperature flue gas is supplied to the pyrolysis reactor as a heat source, thereby reducing external energy requirements and lowering costs. In the high-temperature zone, the pyrolysis products from the medium-temperature zone are gasified with carbon dioxide to produce high-quality synthesis gas, which can be used as fuel or chemical feedstock. 3) The system and process provided in this utility model effectively remove pollutants. Through precise airflow and temperature control in the low- and medium-temperature zones, pollutants such as chlorine and sulfur in the waste are converted to the maximum extent possible in the pyrolysis gas stream. The resulting pollutants, such as hydrogen chloride and hydrogen sulfide, are then fed together with the pyrolysis gas stream into a dechlorination unit for removal. After passing through the dechlorination unit, the pyrolysis gas stream enters the combustion chamber for combustion, producing high-temperature flue gas that provides the heat for the pyrolysis reaction. This process not only improves system safety and operational stability but also prevents the formation of large quantities of pollutants in the gas. 4) The present utility model introduces carbon dioxide as a gasification agent to participate in the high-temperature gasification reaction of household waste, thereby not only achieving the efficient production of high-quality fuel gas but also enabling the resource reuse of CO2, which ascribes a secondary use value to CO2 that is consistent with the goal of coordinated use of household waste resources and high CO2 value creation and contributes to the establishment of an environmentally friendly and low-carbon solid waste treatment system. Figures

[0018] In order to illustrate the technical solution of the embodiments of the present utility model more clearly, the attached drawings, which must be used in the embodiments, are briefly presented below, and it should be understood that the following drawings show only some embodiments of the present utility model, so that they should not be regarded as limiting the scope, and for a generally technical person in the field, other relevant drawings can also be obtained from these drawings without creative work. Fig. Figure 1 is a schematic diagram of a system for producing high-quality synthesis gas from household waste and carbon dioxide according to the present utility model;

[0019] In the figure: 1-Feeder; 2-Dryer; 3-Low-temperature pyrolysis reactor; 4-Medium-temperature pyrolysis reactor; 5-High-temperature pyrolysis reactor; 6-First induced draft fan; 7-Heat exchanger; 8-Combustion chamber; 9-Dechlorination device; 10-Flue gas cleaner; 11-Second induced draft fan; 12-Valve. Specific embodiments

[0020] The technical solutions of this utility model are described clearly and completely below, and it is obvious that the described embodiments represent only some of the embodiments of this utility model and not all of them. Based on the embodiments of this utility model, all other embodiments that ordinary technical personnel obtain without creative effort fall within the scope of protection of this utility model.

[0021] A pyrolysis technology solution suitable for treating household waste is capable of efficiently removing chlorides from household waste through effective segmented temperature control, atmosphere adaptation, and product diversion design. This also promotes the high-quality utilization of resources such as fuel gas and tar, effectively controls the formation and emission of harmful gases like dioxins, ensures the production of high-quality gasification synthesis gas, and meets the requirements of a green, environmentally friendly, and low-carbon household waste treatment technology. In response to the aforementioned problems, the present utility model provides a multi-zone collaborative treatment system for the pyrolysis of household waste, enabling efficient and clean pyrolysis of household waste and the utilization of synthesis gas resources, and exhibiting promising application prospects.

[0022] The system and process provided by the present utility model for producing high-quality synthesis gas from household waste and carbon dioxide, the system comprising: a feeder 1, a dryer 2, a low-temperature pyrolysis reactor 3, a medium-temperature pyrolysis reactor 4, a high-temperature pyrolysis reactor 5, a dechlorination device 9, a combustion chamber 8, a flue gas cleaner 10, a heat exchanger 7, a first induced draft fan 6, a second induced draft fan 11 and a valve 12.

[0023] Dryer 2 consists of an inner chamber and an outer chamber, each equipped with an inlet and an outlet. The inlet is fitted with a sealing device to prevent backflow of hot air. The operating temperature of dryer 2 is regulated between 105 and 150 °C, and temperature monitoring and control are achieved via a temperature sensor. Dryer 2 uses a circulating hot air blower to dry the raw materials, and the moisture content of the raw materials after drying is regulated to below 10%.

[0024] The low-temperature pyrolysis reactor 3 consists of an inner chamber and an outer chamber, each equipped with an inlet and an outlet. The operating temperature of the low-temperature pyrolysis reactor 3 is 150 to 450 °C, and the material residence time is 30 to 80 minutes. The inner wall of the inner chamber of the low-temperature pyrolysis reactor 3 is equipped with several baffles for forward material movement, and the residence time can be adjusted by rotating these baffles. The inner wall of the outer chamber is equipped with several guide vanes for the forward flow of the flue gas, and the flue gas flow rate can be regulated by adjusting the opening of the guide vanes.

[0025] The medium-temperature pyrolysis reactor 4 consists of an inner chamber and an outer chamber, each equipped with an inlet and an outlet. The operating temperature of the medium-temperature pyrolysis reactor 4 is 450 to 600 °C, and the pyrolysis time of the material within this range is 20 to 40 minutes. The inner wall of the inner chamber of the medium-temperature pyrolysis reactor 4 is equipped with several baffles for forward material movement, and the residence time of the material can be adjusted by rotating these baffles. The inner wall of the outer chamber is equipped with several guide vanes for the forward flow of the flue gas, and the flue gas flow rate can be regulated by adjusting the opening of the guide vanes.

[0026] The high-temperature pyrolysis reactor 5 consists of an inner chamber and an outer chamber, each equipped with an inlet and an outlet. The operating temperature of the high-temperature pyrolysis reactor 5 is 600 to 1000 °C, the residence time of the material in this range is 10 to 30 minutes, and carbon dioxide gas with a purity of at least 99% is introduced at a flow rate of 5–20 m³ / h. The inner wall of the inner chamber of the high-temperature pyrolysis reactor 5 is equipped with several baffles for forward material movement, and the residence time of the material can be adjusted by rotating these baffles. The inner wall of the outer chamber is equipped with several guide vanes for the forward flow of the flue gas, and the flow rate of the flue gas can be regulated by adjusting the opening of the guide vanes.

[0027] The dechlorination device 9 comprises an absorbent storage tank, an absorbent spiral feed system, and a mixed reaction chamber. The dechlorination device 9 uses calcium hydroxide powder as the absorbent. The absorbent storage tank is connected to the mixed reaction chamber via a pipeline, and a nozzle is provided in the mixed reaction chamber to spray Ca(OH)₂ into the pyrolysis gas for reaction. The temperature of the mixed reaction chamber is controlled to 200–300 °C, the residence time is 30–60 minutes, and the dechlorination efficiency is over 95%.

[0028] Combustion chamber 8 is a vertical, cylindrical structure and is equipped internally with a grate and an ignition device. The operating temperature of combustion chamber 8 is 800 to 1200 °C, and temperature monitoring and control are achieved via temperature sensors. Several temperature sensors are located in the upper part of combustion chamber 8 to monitor the flue gas temperature, which is precisely controlled by a PLC control system.

[0029] The flue gas cleaner 10 utilizes a multi-stage arrangement of bag filters and activated carbon adsorbers, and the start and stop of each stage of the cleaner can be adjusted via valve 12 according to the actual conditions. The operating temperature of the cleaner is regulated to 150 to 200 °C, and the blow velocity is 5 to 10 m / s. The heat exchanger 7 uses a plate heat exchanger, which enables heat exchange between cold water and warm air through the coordinated operation of the first induced draft fan 6 and the second induced draft fan 11. The heat exchange surface area of ​​the heat exchanger 7 is 50 to 100 m². 2 and the heat exchange efficiency is at least 85%.

[0030] The system also includes an intelligent control system comprising a temperature sensor, a flow meter, and an online detector for hydrogen chloride and hydrogen sulfide. The PLC control system enables precise regulation and automatic temperature adjustment in each zone and optimizes various parameters automatically based on real-time monitoring data. The control system also features a remote monitoring function, allowing users to view the operational status and adjust parameters in real time via mobile terminals.

[0031] As in Fig. As shown in Figure 1, the connections between the different components can be described as follows, based on the flow paths of materials, gases, flue gas and carbon dioxide: Material flow path: Household waste is conveyed from feeder 1 to dryer 2 for drying. The dried material is successively fed into low-temperature pyrolysis reactor 3, medium-temperature pyrolysis reactor 4 and high-temperature pyrolysis reactor 5 for multi-stage pyrolysis reactions.

[0032] Gas flow path: The pyrolysis gas produced in the low-temperature pyrolysis reactor 3 and medium-temperature pyrolysis reactor 4 enters the dechlorination unit 9 for dechlorination. The dechlorinated pyrolysis gas then enters the combustion chamber 8 for combustion, producing high-temperature flue gas. After combustion, the flue gas enters the flue gas cleaner 10 for cleaning. The synthesis gas produced in the high-temperature pyrolysis reactor 5 enters the heat exchanger 7 for heat exchange with cold water, producing hot water. After heat exchange, the synthesis gas enters the dryer 2 and provides a heat source for drying household waste. Flue gas flow path: The high-temperature flue gas produced in combustion chamber 8 passes through the heat exchanger 7 for heat exchange.After heat exchange, the flue gas successively enters the high-temperature pyrolysis reactor 5, the medium-temperature pyrolysis reactor 4, and the low-temperature pyrolysis reactor 3, providing a heat source for the pyrolysis reaction. The flue gas exiting the low-temperature pyrolysis reactor 3 is then transferred to the flue gas cleaner 10 for purification.

[0033] CO2 flow path: CO2 is controlled by valve 12 and enters the high-temperature pyrolysis reactor 5 to participate in the gasification reaction. Function of the auxiliary equipment: The first induced draft fan 6 and the second induced draft fan 11 are designed to guide the gas flow within the system, ensuring that the gas flows between the various components according to the specified flow pattern. Solid residues produced in the low-temperature pyrolysis reactor 3 and the high-temperature pyrolysis reactor 5 are discharged from the system through corresponding outlet openings.

[0034] In the present utility model, household waste is first dewatered in a dryer 2 before entering a low-temperature pyrolysis reactor 3, a medium-temperature pyrolysis reactor 4, and a high-temperature pyrolysis reactor 5 for pyrolysis and gasification reactions. The pyrolysis gas produced in the low-temperature and medium-temperature pyrolysis reactors passes through a dechlorination unit 9 and enters a combustion chamber 8 for combustion, producing high-temperature flue gas. This high-temperature flue gas then enters the high-temperature, medium-temperature, and low-temperature pyrolysis reactors, providing a heat source for the pyrolysis reactions. Finally, it enters a flue gas cleaner 10 to comply with emission regulations.The high-temperature pyrolysis reactor 5 introduces carbon dioxide and medium-temperature coal to carry out a gasification reaction. The high-temperature CO, CH4, and other high-quality synthesis gases produced after the reaction are transferred to the heat exchanger 7, where they are used to generate hot water for external use through heat exchange with cold water. After heat exchange, the synthesis gas enters the dryer 2 to dry the household waste, yielding high-quality synthesis gas at a low temperature. This utility model utilizes indirect heat exchange with high-temperature flue gas to perform a multi-stage pyrolysis reaction of household waste. This allows for adjustable reaction temperatures and times in each reaction zone, thus ensuring the complete decomposition and resource utilization of complex household waste components.The present utility model does not require an external heat source, but uses the heat provided by the household waste itself for the pyrolysis and gasification reactions, thereby improving the pyrolysis efficiency and energy self-sufficiency of the household waste, effectively controlling the generation and release of pollutants such as chlorine, taking into account both environmental protection and economic efficiency, and is suitable for the construction of an environmentally friendly and low-carbon system for the treatment of household waste resources and has broad industrial application prospects. Example 1

[0035] Household waste is fed into the dryer at a consistent rate of 50 kg / h via a feeder for drying.

[0036] In the dryer, the raw material is pre-dried, the moisture content of the dried household waste is regulated to approximately 10% by adjusting the synthesis gas temperature and flow rate, and the dried household waste is then introduced into the low-temperature zone of the pyrolysis gasification reactor.

[0037] The low-temperature zone is set to 400 °C, where the material is pyrolyzed for one hour, with the low-temperature pyrolysis gas being directed to the dechlorination unit and the low-temperature coal produced by the pyrolysis in the low-temperature zone being directed to the medium-temperature zone.

[0038] The medium temperature zone is set to 500 °C, where the material is pyrolyzed for 30 minutes, with the generated medium temperature pyrolysis gas being fed into the dechlorination unit and the medium temperature coal produced by the pyrolysis in the medium temperature zone being directed into the high temperature zone.

[0039] In the dechlorination unit, the pyrolysis gas is dechlorinated by injecting Ca(OH)2 and the dechlorinated pyrolysis gas then enters the combustion chamber for combustion, producing high-temperature flue gas.

[0040] Air with an excess air ratio of 1.2 is introduced into the combustion chamber, the resulting high-temperature flue gas is tempered by the supply of cold air to maintain a temperature of 1100 °C, the flue gas then undergoes heat exchange with the materials in the high-temperature, medium-temperature and low-temperature zones, and finally the flue gas enters the cleaning system for cleaning and discharge.

[0041] The high-temperature zone is set to 900 °C, the CO2 flow rate is set to 10 m 3 The flow rate is regulated to ensure sufficient gasification, and the materials gasify in this zone for 30 minutes, with the resulting high-temperature gas being introduced into a heat exchanger for heat exchange with cold water, thereby generating usable hot water and simultaneously cooling the gasified synthesis gas to 200 °C.

[0042] The cooled synthesis gas is then directed into a dryer for heat exchange with household waste, ultimately producing a high-quality low-temperature synthesis gas containing CO, CH4 and other gases.

[0043] It should be noted that the terms "first," "second," etc., are used in the description and claims of this utility model, as well as in the accompanying drawings, to distinguish similar objects and do not necessarily serve to describe a specific order or sequence. It is understood that the terms used in this way are interchangeable, so that the embodiments of this utility model described herein may be implemented in a different order than that shown or described here. Furthermore, the terms "comprise" and "feature," and all variations thereof, are intended to cover non-exclusive inclusion.For example, a process, procedure, system, product or device comprising a series of steps or units is not necessarily limited to the steps or units expressly listed, but may include further steps or units not expressly listed or inherent in such process, procedure, product or device.

[0044] Unless expressly stated otherwise and limited, the terms "install," "connect," "link," and "fasten" in this utility model are to be understood in a broad sense. For example, it may be a permanent connection, a detachable connection, or an integral connection; it may be a mechanical connection, an electrical connection, or a communicative connection; it may be a direct connection, an indirect connection via an intermediate medium, a connection within the two elements, or an interaction between the two elements. For general technical personnel in this field, the specific meaning of the aforementioned terms in this utility model may be understood according to the specific circumstances.When a component is described as "attached" to another component, it may be directly attached to the other component, or there may be an intervening component. When a component is described as "connected" to another component, it may be directly attached to the other component, or there may be an intervening component. When a component is described as "arranged on" another component, it may be arranged directly on top of the other component, or there may be an intervening component.Unless expressly and specifically stated otherwise and limited, in this utility model, the following may mean that if a first feature is "above" or "below" a second feature, the first feature and the second feature are in direct contact, or that the first feature and the second feature are not in direct contact but may be connected via another feature between them. Furthermore, the indication that a first feature is "above," "above," and "on" a second feature may mean that the first feature is located directly above or obliquely above the second feature, or simply that the first feature is located on a higher horizontal plane than the second feature. If a first feature... The phrase "below" or "under" a second feature can mean that the first feature is located directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal height than the second feature.

[0045] It is understood that the terms “comprise” and “contain” in this description and the accompanying claims indicate the presence of the described features, wholes, steps, operations, elements and / or assemblies, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, assemblies and / or combinations thereof.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as understood by a person skilled in the art in the field of this invention. The terminology used in the description of this utility model serves solely to describe specific embodiments and is not intended to limit the scope of this utility model. The term "and / or" used herein encompasses all combinations of one or more of the associated listed elements.

[0047] The above description merely presents preferred embodiments of the present utility model and does not constitute any limitation of the present utility model; any generally skilled technical personnel in the industry can easily implement the present utility model as shown in the accompanying drawings of the description and as described above; however, equivalent changes, modifications and further developments made by those skilled in the art using the technical content disclosed above, without deviating from the scope of protection of the present utility model, all constitute equivalent embodiments of the present utility model; at the same time, all equivalent changes, modifications and further developments of the above embodiments that are based on the essential technology of the present utility model remain within the scope of protection of the present utility model.

Claims

[1] System for producing high-quality synthesis gas from household waste and carbon dioxide, characterized by , that it comprises: a feeder (1), a dryer (2), a low-temperature pyrolysis reactor (3), a medium-temperature pyrolysis reactor (4) and a high-temperature pyrolysis reactor (5) connected in series; wherein the pyrolysis gas outlets of the low-temperature pyrolysis reactor (3) and the medium-temperature pyrolysis reactor (4) are successively connected to a dechlorination device (9) and a combustion chamber (8); wherein the flue gas outlet of the combustion chamber (8) is successively connected to the flue gas lines of the high-temperature pyrolysis reactor (5), the medium-temperature pyrolysis reactor (4) and the low-temperature pyrolysis reactor (3) as well as to the flue gas cleaner (10); The synthesis gas outlet of the high-temperature pyrolysis reactor (5) is successively connected to a heat exchanger (7) and a dryer (2). [2] System for producing high-quality synthesis gas from household waste and carbon dioxide according to claim 1, characterized by , that the dryer (2), the low-temperature pyrolysis reactor (3), the medium-temperature pyrolysis reactor (4) and the high-temperature pyrolysis reactor (5) each adopt a two-chamber structure comprising an inner chamber and an outer chamber, wherein the inner chamber is provided with a material guide plate and the outer chamber with a flue gas guide vane and each reactor forms a flue gas circuit with the combustion chamber (8) via the heat exchanger (7). [3] System for producing high-quality synthesis gas from household waste and carbon dioxide according to claim 1, characterized by , that a first induced draft fan (6) is provided on the pipeline between heat exchanger (7) and dryer (2). [4] System for producing high-quality synthesis gas from household waste and carbon dioxide according to claim 1, characterized by, that a valve (12) is provided on the carbon dioxide inlet line of the high-temperature pyrolysis reactor (5). [5] System for producing high-quality synthesis gas from household waste and carbon dioxide according to claim 1, characterized by , that a second induced draft fan (11) is provided on the discharge pipe of the flue gas cleaner (10). [6] System for producing high-quality synthesis gas from household waste and carbon dioxide according to claim 1, characterized by , that a sealing device is provided at the inlet of the dryer (2). [7] System for producing high-quality synthesis gas from household waste and carbon dioxide according to claim 1, characterized by, that the dryer (2), the low-temperature pyrolysis reactor (3), the medium-temperature pyrolysis reactor (4) and the high-temperature pyrolysis reactor (5) are each equipped with a PLC control unit and an automated setting module, wherein closed control of temperature, flue gas flow and material residence time of each zone is carried out via temperature sensors, flow meters and online detectors for hydrogen chloride and hydrogen sulfide. [8] System for producing high-quality synthesis gas from household waste and carbon dioxide according to claim 1, characterized by , that the dechlorination device (9) is equipped with an absorbent spiral feed system and a mixing reaction chamber and uses calcium hydroxide dry powder as the absorbent.

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