Self-heating garbage pyrolysis gasification system and operation method thereof

Abstract

The present invention discloses a self-heating garbage pyrolysis gasification system with simple process and low operation cost and its operation method. The system includes a garbage feeding device, an oxygen-free pyrolysis gasification furnace, a catalytic cracking device and a synthesis gas purification device connected in sequence, and also includes an air preheater. A heat storage heating device is arranged on the periphery of the oxygen-free pyrolysis gasification furnace. The lower part of the heat storage heating device is a combustion chamber. Between the heat storage heating device and the oxygen-free pyrolysis gasification furnace is a flue gas channel connected to the combustion chamber. During operation, the combustion gas of the combustion chamber comes from the synthesis gas pipeline after the synthesis gas purification device, and the air of the combustion chamber comes from the air pipeline after the air preheater that exchanges heat with the flue gas generated in the combustion chamber. The system heats the oxygen-free pyrolysis gasification furnace by high-temperature flue gas outside the furnace, which is convenient for the structural arrangement in the pyrolysis gasification furnace. The temperature in the furnace is stable and controllable. The whole system operates by self-heating. The purification treatment is concentrated in the synthesis gas purification device, and the flue gas treatment device can be omitted.

Description

Technical Field

[0001] The invention relates to a pyrolysis treatment technology for garbage, in particular to a system for anaerobic pyrolysis and gasification of domestic garbage and self-heating operation. Background Art

[0002] The amount of urban domestic waste has increased rapidly with the development of urbanization, which has brought about a series of environmental problems such as land occupation and environmental pollution. At present, the more mature ways to deal with waste mainly include landfill, composting, incineration and other end-of-life treatment processes. Among them, waste incineration has the advantages of large volume reduction, high harmless treatment rate and resource utilization. At the same time, due to the fact that the existing landfills tend to be saturated (or overloaded) and the strict site selection of new landfills, waste incineration is currently one of the main development directions of domestic waste treatment.

[0003] As we all know, there are a lot of chlorinated phenols, chloride salts and other chlorine-containing substances in domestic garbage. Dioxins are produced in the oxidizing atmosphere during garbage incineration. The International Agency for Research on Cancer has identified dioxins as the number one carcinogenic risk as early as 1997. At present, dioxins produced during garbage incineration need to be controlled by multiple equipment such as "3T+E" and activated carbon injection to achieve emission reduction, and the investment cost of environmental protection facilities is high; because dioxin is a strong carcinogen, garbage incineration power generation projects often face panic and protests from surrounding residents, causing serious garbage incineration avoidance effects.

[0004] Pyrolysis gasification generally refers to the technology of converting carbon-containing materials, such as coal, biomass and garbage, into a synthesis gas composed of simple molecules such as CO, CO2, H2 and CH4 after chemical reaction with gasification media, such as air, pure oxygen, hydrogen and water vapor, at a certain temperature and pressure (pressurized or normal pressure). Among them, isolating / reducing air treatment in anaerobic pyrolysis gasification reaction can inhibit the production of dioxins from a mechanism point of view, and is considered to be the next generation of waste thermochemical treatment technology after incineration. Garbage pyrolysis requires a lot of heat consumption. At present, many pyrolysis treatment processes use electric heating or external heating to provide heat, which consumes a lot of energy and has complex process equipment systems. The heat recovery method of the pyrolysis process products is mainly to exchange the pyrolysis gas with the air preheater.

[0005] The publication number CN106497587A published on March 15, 2017, "A heat storage type garbage pyrolysis treatment system and method thereof", uses a built-in heat storage type radiation tube to provide a heat source for the pyrolysis furnace, realizes air preheating and flue gas waste heat utilization through the heat storage material of the ceramic honeycomb material, and the heat storage bodies on both sides of the pyrolysis furnace work intermittently according to the temperature and time settings; and the flue gas is used for garbage preheating. The built-in radiation tube of the device may cause garbage to be blocked in the pyrolysis furnace, or the pipe may be contaminated to affect heat conduction. The heat of the high-temperature semi-coke, synthesis gas and exhaust flue gas generated by the furnace body has not been fully utilized, and there is still room for improvement. Summary of the invention

[0006] In order to overcome the shortcomings of the unreasonable structure of the existing garbage pyrolysis system, the technical problem to be solved by the present invention is to provide a self-heating garbage pyrolysis gasification system with simple process and low operating cost and an operating method thereof.

[0007] The technical solution adopted by the present invention to solve its technical problems is: a self-heating garbage pyrolysis and gasification system, including a garbage feeding device, an anaerobic pyrolysis and gasification furnace, a catalytic cracking device and a synthesis gas purification device connected in sequence, and also including an air preheater. A heat storage heating device is arranged on the periphery of the anaerobic pyrolysis and gasification furnace, the lower part of the heat storage heating device is a combustion chamber, and a flue gas channel connected to the combustion chamber is between the heat storage heating device and the anaerobic pyrolysis and gasification furnace. The combustion gas of the combustion chamber comes from the synthesis gas pipeline after the synthesis gas purification device, and the air of the combustion chamber comes from the air pipeline after the air preheater that exchanges heat with the flue gas generated in the combustion chamber. This system sets a heat storage heating device outside the pyrolysis gasification furnace which uses the purified synthesis gas as fuel. The oxygen-free pyrolysis gasification furnace is heated by the high-temperature flue gas outside the furnace, and air does not enter the pyrolysis gasification furnace, thereby realizing oxygen-free pyrolysis of garbage, facilitating the arrangement of the raw material and product conveying structure in the pyrolysis gasification furnace, and the temperature in the furnace is stable and controllable. The treatment device for the combustion flue gas can be omitted, and the purification treatment of the entire system is concentrated in the synthesis gas purification device, and the system composition is simple.

[0008] Furthermore, a waste heat utilization device is arranged in the flue gas pipeline after the air preheater, in which at least a part of the high-temperature steam generated by heat exchange between water and flue gas from the flue gas channel is sent to the catalytic cracking device to promote the catalytic conversion of tar in the synthesis gas. The heat of the high-temperature flue gas in the combustion chamber is used to generate the high-temperature steam required for cracking, thereby improving the comprehensive utilization efficiency of heat.

[0009] Furthermore, the system also includes a cooling heat exchanger, in which the water entering the waste heat utilization device exchanges heat with the synthesis gas derived from the catalytic cracking device, and the synthesis gas after heat exchange enters the synthesis gas purification device. The high-temperature steam required for cracking is generated by heat exchange between the feed water, the synthesis gas and the high-temperature flue gas in the combustion chamber, and the surplus steam can be used for other purposes, which not only improves the comprehensive utilization efficiency of heat, but also reduces the cooling requirements of the subsequent synthesis gas purification device.

[0010] The synthesis gas purification device includes a water bath dust removal device and a purification device in sequence, and the purification device performs chlorine removal and acid removal. In the water bath dust removal device, the synthesis gas is washed, cooled and dusted by spraying water, and then reacted with sodium bicarbonate, sodium hydroxide and other solutions in the purification device to remove acid gases such as HCL and HF in the pyrolysis synthesis gas to obtain clean high calorific value synthesis gas.

[0011] An induced draft fan and a chimney are connected in series in the flue gas pipeline behind the waste heat utilization device to guide the flow of flue gas and discharge the flue gas.

[0012] A blower is connected in front of the air inlet of the air preheater to facilitate the introduction of the air into the combustion chamber after preheating and to adjust the air flow entering the combustion chamber.

[0013] A fuel gas booster and a synthesis gas buffer storage tank are connected in series in the synthesis gas pipeline after the synthesis gas purification device.

[0014] The synthesis gas is introduced into the combustion chamber through the synthesis gas pipeline behind the synthesis gas buffer tank, that is, the purified synthesis gas is connected back between the pipeline and the combustion chamber to use as fuel, ensuring a reliable clean fuel supply for the thermal storage heating device.

[0015] A synthesis gas buffer storage tank is connected in series in the synthesis gas pipeline after the synthesis gas purification device, and the purified synthesis gas that cannot be consumed in time can be temporarily stored in the storage tank.

[0016] The furnace body of the oxygen-free pyrolysis gasification furnace is made of refractory heat-conducting castable material, and the side of the heat storage heating device away from the oxygen-free pyrolysis gasification furnace is made of refractory heat-insulating castable material.

[0017] The present invention also provides an operation method of a self-heating garbage pyrolysis and gasification system, which includes a garbage feeding device, an anaerobic pyrolysis and gasification furnace, a catalytic cracking device and a synthesis gas purification device connected in sequence, and also includes an air preheater. A heat storage heating device is arranged on the periphery of the anaerobic pyrolysis and gasification furnace, and the lower part of the heat storage heating device is a combustion chamber. A flue gas channel connected to the combustion chamber is provided between the heat storage heating device and the anaerobic pyrolysis and gasification furnace; the garbage is fed into the middle and upper area of ​​the anaerobic pyrolysis and gasification furnace through the garbage feeding device for high-temperature drying and dehydration, and the anaerobic pyrolysis and gasification furnace is heated in the middle and lower area of ​​the anaerobic pyrolysis and gasification furnace. The working temperature of the anaerobic pyrolysis area is controlled to be between 700 and 800°C. The generated residue is discharged from the bottom of the anaerobic pyrolysis gasifier. The generated synthesis gas is led out of the anaerobic pyrolysis gasifier and sent to the catalytic cracking device. In the catalytic cracking device, the tar in the synthesis gas is cracked. Then, the synthesis gas led out of the catalytic cracking device is purified by the synthesis gas purification device and then stored in the synthesis gas buffer tank. The combustion gas of the combustion chamber comes from the synthesis gas pipeline after the synthesis gas purification device, and the air of the combustion chamber comes from the air pipeline after the air preheater that exchanges heat with the flue gas generated in the combustion chamber. By arranging the air preheater, the combustion state of the combustion chamber of the heat storage heating device can be stabilized, which is conducive to the comprehensive utilization of heat of the entire system and the maintenance of the self-heating operation of the self-heating garbage pyrolysis gasification system.

[0018] Furthermore, a waste heat utilization device is arranged in the flue gas pipeline after the air preheater. The high-temperature flue gas generated in the combustion chamber is higher than 1200°C, and the heat is transferred to the oxygen-free pyrolysis gasification furnace by radiation and heat conduction. The outlet flue gas temperature of the heat storage heating device is controlled to enter the air preheater when it is below 700°C. The combustion chamber air sent into the air preheater by the blower is preheated to above 400°C, and then the high-temperature flue gas enters the waste heat utilization device for cooling. In the waste heat utilization device, at least a part of the high-temperature steam generated by heat exchange between water and the flue gas from the flue gas channel is sent to the catalytic cracking device. After cooling, the flue gas is discharged into the atmosphere through the induced draft fan and the chimney. The temperature of the preheated air is a temperature that is calculated by the inventor to be conducive to achieving the heat balance of the system. In this way, the flue gas passing through the air preheater still has a temperature of more than 400°C, and contains heat energy that can be utilized. Therefore, the waste heat utilization device is used to generate high-temperature steam for use by the catalytic cracking device or for external use by users, which is conducive to full utilization of heat.

[0019] The beneficial effects of the present invention are as follows: by arranging a heat storage heating device using purified synthesis gas as fuel outside the pyrolysis furnace, anaerobic pyrolysis of garbage is achieved, and the reasonable arrangement of the air preheater, the waste heat treatment device and the cooling heat exchanger is used to improve the heat utilization efficiency, and the combustion flue gas treatment device can be omitted. The purification treatment of the entire system is concentrated in the synthesis gas purification device. The system composition is simple, the comprehensive heat utilization efficiency is high, and the economic benefits are significant. After startup, self-heating pyrolysis can be achieved, the output energy is clean, which is conducive to achieving ultra-clean emissions and is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the composition of the self-heating garbage pyrolysis and gasification system of the present invention.

[0021] The markings in the figure are: 1-garbage feeding device, 2-oxygen-free pyrolysis gasification furnace, 3-catalytic cracking device, 4-cooling heat exchanger, 5-water bath dust removal device, 6-purification device, 7-gas booster, 8-synthesis gas buffer storage tank, 9-thermal storage heating device, 10-air preheater, 11-waste heat utilization device, 12-induced draft fan, 13-chimney, 14-forced air fan. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0023] like Figure 1 As shown, the self-heating domestic waste pyrolysis and gasification utilization system of the present invention comprises: a garbage feeding device 1, an oxygen-free pyrolysis and gasification furnace 2, a catalytic cracking device 3, a cooling heat exchanger 4, a water bath dust removal device 5, a purification device 6, a gas booster 7, a synthesis gas buffer storage tank 8, a heat storage heating device 9, an air preheater 10, a waste heat utilization device 11, an induced draft fan 12, a chimney 13, a blower 14, etc. The outlet of the garbage feeding device 1 is connected to the inlet of the oxygen-free pyrolysis and gasification furnace 2, and the outlet of the oxygen-free pyrolysis and gasification furnace 2 is connected to the catalytic cracking device 3, the cooling heat exchanger 4, the water bath dust removal device 5, and the purification device 6 in sequence. The pyrolysis and gasification synthesis gas undergoes cracking, cooling, water bath dust removal, and chlorine and acid removal treatment processes of the purification device 6 to obtain clean synthesis gas.

[0024] The regenerative heating device 9 is arranged around the outer side of the oxygen-free pyrolysis gasification furnace 2, and a flue gas channel (upper) and a gas combustion chamber (lower) are formed between the two. Part of the returned clean synthesis gas enters the gas combustion chamber at the lower part of the regenerative heating device to burn and generate heat. The high-temperature flue gas transfers heat to the inside of the oxygen-free pyrolysis gasification furnace 2 by radiation and heat conduction, providing the heat required for the waste pyrolysis reaction. The inner side of the regenerative heating device 9 is a furnace body with refractory heat-conducting castables laid on it, so as to quickly transfer heat to the oxygen-free pyrolysis gasification furnace 2. The outer side of the regenerative heating device 9 is laid with refractory heat-insulating castables to reduce heat dissipation.

[0025] The air preheater 10 is connected to the flue gas outlet of the heat storage heating device 9, and preheats the combustion air sent in by the blower 14. The high-temperature flue gas after heat exchange enters the waste heat utilization device 11 for cooling, and then is discharged into the atmosphere through the induced draft fan 12 and the chimney 13. Since clean synthesis gas is used for combustion, there is no need to treat the flue gas before discharge. The steam-water inlet of the waste heat utilization device 11 is connected to the steam-water outlet of the cooling heat exchanger 4. The feed water enters the waste heat utilization device 11 after being heated by the cooling heat exchanger 4 to generate steam. A part of the steam is sent to the catalytic cracking device 3 to crack the tar in the synthesis gas, so that the tar in the synthesis gas is cracked to generate new synthesis gas, and the remaining high-temperature steam can be consumed by external users.

[0026] Part of the returned clean synthesis gas enters the combustion chamber at the bottom of the regenerative heating device to burn and generate heat. The high-temperature flue gas with a temperature of more than 1200°C transfers heat evenly from the refractory heat-conducting castable to the oxygen-free pyrolysis gasifier 2 through radiation and heat conduction, thereby realizing the self-heating operation of the system. The flue gas with an outlet temperature of about 700°C of the regenerative heating device enters the air preheater 10, and the combustion air sent into the air preheater 10 by the blower 14 is preheated to above 400°C. Subsequently, the high-temperature flue gas enters the waste heat utilization device 11 for cooling, and is discharged into the atmosphere through the induced draft fan 12 and the chimney 13.

[0027] The working process is as follows: after pre-treatment such as drying and fermentation, leachate precipitation, debris screening and crushing, the garbage or biomass raw materials are sent to the oxygen-free pyrolysis gasification furnace 2 through the garbage feeding device 1, and high-temperature drying and dehydration are carried out in the middle and upper area of ​​the oxygen-free pyrolysis gasification furnace 2, and oxygen-free pyrolysis is carried out in the middle and lower area of ​​the oxygen-free pyrolysis gasification furnace 2 with an average working temperature of 700-800°C. The generated residue is discharged from the bottom, and the synthesis gas is led out from the side pipe at the bottom of the oxygen-free pyrolysis gasification furnace 2 and sent to the catalytic cracking device 3. In the catalytic cracking device 3, the high-temperature steam and Under the action of nickel-based or charcoal, or dolomite and other catalysts, the tar in the synthesis gas is cracked, and then the synthesis gas is cooled by one or more stages of cooling heat exchangers 4, and then enters the water bath dust removal device 5 to use spray water washing to cool and remove dust, and then enters the purification device 6 to react with sodium bicarbonate, sodium hydroxide and other solutions to remove acid gases such as HCL and HF in the pyrolysis synthesis gas to obtain clean high calorific value synthesis gas, which is pressurized by the gas booster 7 and enters the synthesis gas buffer storage tank 8 for storage. The clean synthesis gas can be used for power generation or consumption by downstream users according to the system application scenario and user needs.

[0028] Embodiment 1:

[0029] like Figure 1As shown, the negative pressure self-heating domestic waste anaerobic pyrolysis gasification utilization system comprises: a waste feeding device 1, an anaerobic pyrolysis gasification furnace 2, a catalytic cracking device 3, a cooling heat exchanger 4, a water bath dust removal device 5, a purification device 6, a gas booster 7, a synthesis gas buffer storage tank 8, a thermal storage heating device 9, an air preheater 10, a waste heat utilization device 11, an induced draft fan 12, a chimney 13, a blower 14, etc.

[0030] The garbage feeding device 1 of the present invention feeds garbage or biomass into the middle and upper area of ​​the oxygen-free pyrolysis gasification furnace 2 for high-temperature drying and dehydration, and performs oxygen-free pyrolysis in the middle and lower area with an average working temperature between 700 and 800°C. The generated residue is discharged from the bottom, and the synthesis gas is led out from the side pipe at the lower part of the oxygen-free pyrolysis gasification furnace 2 and sent to the catalytic cracking device 3. Under the action of the steam provided by the waste heat utilization device 11 and the nickel-based or charcoal, or dolomite catalyst in the catalytic cracking device 3, the tar in the synthesis gas is cracked, and then the synthesis gas is cooled by the first or multi-stage cooling heat exchanger 4 and enters the water bath dust removal. Device 5 utilizes spray water for washing, cooling and dust removal, and then enters purification device 6 to react with sodium bicarbonate, sodium hydroxide and other solutions to remove acid gases such as HCL and HF in the pyrolysis synthesis gas, so as to obtain clean high calorific value synthesis gas. By adjusting the output of the synthesis gas regulating door at the outlet of purification device 6 and the gas booster 7, the pipeline and equipment between the anaerobic pyrolysis gasifier 2 and the gas booster 7 are controlled to be in a negative pressure state. After being pressurized by the gas booster 7, the synthesis gas enters the synthesis gas buffer storage tank 8 for storage. The clean synthesis gas can be used for power generation or nearby consumption by downstream users according to the system application scenario and user needs. Part of the returned clean synthesis gas enters the combustion chamber at the bottom of the regenerative heating device to burn and generate heat. The high-temperature flue gas with a temperature greater than 1200°C transfers heat evenly from the refractory heat-conducting castable to the oxygen-free pyrolysis gasifier 2 through radiation and heat conduction, thereby realizing the self-heating operation of the system. The flue gas with an outlet temperature of ~700°C of the regenerative heating device enters the air preheater 10, and the combustion air sent into the air preheater 10 by the blower 14 is preheated to above 400°C. Subsequently, the high-temperature flue gas enters the waste heat utilization device 11 for cooling, and the flue gas meeting the ultra-clean emission index is discharged into the atmosphere through the induced draft fan 12 and the chimney 13.

[0031] The self-heating domestic waste anaerobic pyrolysis gasification utilization system operating under negative pressure can simplify the design of the sealing structure of the connection parts of each component and reduce investment costs.

[0032] The operation process of the system is as follows.

[0033] After the garbage or biomass raw materials are dried and fermented, the leachate is precipitated, the debris is screened and crushed, and then they are sent to the middle and upper area of ​​the oxygen-free pyrolysis gasification furnace 2 through the garbage feeding device 1 for high-temperature drying and dehydration. In the middle and lower area with an average working temperature of 700-800°C, oxygen-free pyrolysis is carried out, and the generated residue is discharged from the bottom. The synthesis gas is led out from the side pipe at the bottom of the oxygen-free pyrolysis gasification furnace 2 and sent to the catalytic cracking device 3. Under the catalytic action of the steam provided by the waste heat utilization device 11 and the charcoal, dolomite or nickel-based catalyst in the catalytic cracking device 3, the synthesis gas is The tar is cracked, and then the synthesis gas is cooled by one or more cooling heat exchangers 4, and then enters the water bath dust removal device 5 to use spray water washing to cool and remove dust, and then enters the purification device 6 to react with sodium bicarbonate, sodium hydroxide and other solutions to remove acid gases such as HCL and HF in the pyrolysis synthesis gas to obtain a clean high calorific value synthesis gas, which is pressurized by the gas booster 7 and then enters the synthesis gas buffer storage tank 8 for storage. The synthesis gas can be used for pyrolysis gasification of domestic waste for power generation or consumed by users in downstream factories and workshops according to the system application scenario and user needs. Part of the returned clean synthesis gas enters the combustion chamber at the bottom of the regenerative heating device to burn and generate heat. The high-temperature flue gas with a temperature of more than 1200°C transfers heat evenly from the refractory heat-conducting castable to the oxygen-free pyrolysis gasifier 2 through radiation and heat conduction, thereby realizing the self-heating operation of the system. The flue gas with an outlet temperature of about 700°C of the regenerative heating device enters the air preheater 10, and the combustion air sent into the air preheater 10 by the blower 14 is preheated to above 400°C. Subsequently, the high-temperature flue gas enters the waste heat utilization device 11 for cooling, and is discharged into the atmosphere through the induced draft fan 12 and the chimney 13.

[0034] In the system, the gas-solid separation of residual carbon and synthesis gas is achieved through the anaerobic pyrolysis and gasification of domestic garbage, thereby reducing the amount of domestic garbage. Compared with aerobic pyrolysis and incineration of garbage, the anaerobic pyrolysis and gasification method of isolating air effectively avoids the generation of dioxins, and the anaerobic pyrolysis and gasification method avoids the dilution of effective synthesis gas by N2 to obtain synthesis gas with high calorific value, thereby improving the energy utilization efficiency. The purified synthesis gas is obtained through the simple process of water bath dust removal and chlorine and acid removal, which reduces the processing cost and is also conducive to the subsequent gas-fired power generation or the nearby consumption of domestic gas, as well as the high value-added fine processing of synthesis gas. The present invention uses part of the purified synthesis gas to return to the heat storage heating device, and the heat generated by the combustion provides a pyrolysis temperature of 700-800°C for the anaerobic pyrolysis and gasification furnace, realizing the self-heating operation of the anaerobic pyrolysis furnace, and the other part of the synthesis gas is consumed by users, thereby maximizing the reduction of garbage and resource utilization. The system uses an air preheater to recover part of the heat to heat the combustion-supporting air, and further recovers the heat using a waste heat utilization device. The self-heating garbage pyrolysis and gasification system of the present invention has a simple, stable and reliable structure, a high resource utilization rate, and significant economic benefits. The entire system can achieve ultra-clean emission indicators.

[0035] Embodiment 2:

[0036] Except that the system composition of this embodiment does not include the gas booster 7 of embodiment 1, the rest of the structure and connection relationship are the same as those of embodiment 1. The synthesis gas from the purification device 6 is directly sent to the synthesis gas buffer storage tank 8 for storage. By adjusting the synthesis gas regulating door at the outlet of the purification device 6, the pipeline and equipment between the anaerobic pyrolysis gasification furnace 2 and the synthesis gas buffer storage tank 8 are controlled to be in a positive pressure state. The self-heating domestic waste anaerobic pyrolysis gasification utilization system operating under positive pressure can reduce the operating cost because it does not need to be equipped with a gas booster 7, but has high requirements for the sealing of the connection parts of each component.

Claims

1. A self-heating garbage pyrolysis and gasification system, comprising a garbage feeding device (1), an oxygen-free pyrolysis and gasification furnace (2), a catalytic cracking device (3) and a synthesis gas purification device connected in sequence, characterized in that: It also includes an air preheater (10). A regenerative heating device (9) is arranged on the periphery of the oxygen-free pyrolysis gasification furnace (2). The lower part of the regenerative heating device (9) is a combustion chamber. A flue gas passage connected to the combustion chamber is located between the regenerative heating device (9) and the oxygen-free pyrolysis gasification furnace (2). The combustion gas of the combustion chamber comes from the synthesis gas pipeline after the synthesis gas purification device. The air of the combustion chamber comes from the air pipeline after the air preheater (10) that exchanges heat with the flue gas generated in the combustion chamber. A waste heat utilization device (11) is arranged in the flue gas pipeline after the air preheater (10). In the waste heat utilization device (11), at least a portion of the high-temperature steam generated by heat exchange between water and the flue gas from the flue gas passage is sent to the catalytic cracking device (3).

2. The self-heating garbage pyrolysis and gasification system according to claim 1, characterized in that: The system further comprises a cooling heat exchanger (4), in which water entering the waste heat utilization device (11) exchanges heat with synthesis gas output from the catalytic cracking device (3), and the synthesis gas after heat exchange enters the synthesis gas purification device.

3. The self-heating garbage pyrolysis gasification system according to claim 1 or 2, characterized in that: The synthesis gas purification device comprises a water bath dust removal device (5) and a purification device (6) in sequence, and the purification device (6) completes chlorine removal and acid removal treatment.

4. The self-heating garbage pyrolysis gasification system according to claim 1 or 2, characterized in that: A fuel gas booster (7) and a synthesis gas buffer storage tank (8) are sequentially connected in series in the synthesis gas pipeline after the synthesis gas purification device.

5. The self-heating garbage pyrolysis and gasification system according to claim 4 is characterized in that: The synthesis gas is introduced into the combustion chamber through the synthesis gas pipeline behind the synthesis gas buffer storage tank (8).

6. The self-heating garbage pyrolysis gasification system as described in 1 or 2 is characterized by: A synthesis gas buffer storage tank (8) is connected in series in the synthesis gas pipeline after the synthesis gas purification device.

7. The self-heating garbage pyrolysis gasification system according to claim 1 or 2, characterized in that: The furnace body of the oxygen-free pyrolysis gasification furnace (2) is made of refractory heat-conducting castable material, and the side of the heat storage heating device (9) away from the oxygen-free pyrolysis gasification furnace (2) is made of refractory heat-insulating castable material.

8. An operating method of a self-heating garbage pyrolysis and gasification system, the self-heating garbage pyrolysis and gasification system comprising a garbage feeding device (1), an oxygen-free pyrolysis and gasification furnace (2), a catalytic cracking device (3) and a synthesis gas purification device connected in sequence, wherein: The invention also comprises an air preheater (10); a heat storage heating device (9) is arranged on the periphery of the oxygen-free pyrolysis gasification furnace (2); the lower part of the heat storage heating device (9) is a combustion chamber; a flue gas passage connected to the combustion chamber is provided between the heat storage heating device (9) and the oxygen-free pyrolysis gasification furnace (2); garbage is fed into the middle upper area of ​​the oxygen-free pyrolysis gasification furnace (2) through the garbage feeding device (1) for high-temperature drying and dehydration, and oxygen-free pyrolysis is carried out in the middle lower area of ​​the oxygen-free pyrolysis gasification furnace (2); and the control The working temperature of the oxygen-free pyrolysis zone is between 700°C and 800°C. The generated residue is discharged from the bottom of the oxygen-free pyrolysis gasifier (2). The generated synthesis gas is drawn out from the oxygen-free pyrolysis gasifier (2) and sent to the catalytic cracking device (3). In the catalytic cracking device (3), the tar in the synthesis gas is cracked. Subsequently, the synthesis gas drawn out from the catalytic cracking device (3) is purified by the synthesis gas purification device and then enters the synthesis gas buffer storage tank (8) for storage. The combustion gas in the combustion chamber comes from The synthesis gas pipeline originates from after the synthesis gas purification device, and the air of the combustion chamber originates from the air pipeline after the air preheater (10) that exchanges heat with the flue gas generated in the combustion chamber. A waste heat utilization device (11) is arranged in the flue gas pipeline after the air preheater (10). The high-temperature flue gas generated in the combustion chamber at a temperature higher than 1200°C transfers heat to the oxygen-free pyrolysis gasification furnace (2) by radiation and heat conduction. The outlet flue gas temperature of the heat storage heating device (9) is controlled to be below 700°C before entering the air preheater (10). The combustion chamber air sent into the air preheater (10) by the blower (14) is preheated to above 400°C. Subsequently, the high-temperature flue gas enters the waste heat utilization device (11) for cooling. In the waste heat utilization device (11), at least a portion of the high-temperature steam generated by heat exchange between water and the flue gas from the flue gas channel is sent to the catalytic cracking device (3). After cooling, the flue gas is discharged into the atmosphere through the induced draft fan (12) and the chimney (13).

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