Low-nitrogen pyrolysis incineration system and method for household garbage

Abstract

The application discloses a kind of domestic waste low-nitrogen pyrolysis incineration system and method.System includes pyrolysis device and combustion reactor, pyrolysis gas outlet is connected with multiple pyrolysis gas inlets respectively;Combustion reactor includes multiple pyrolysis gas inlets, high-temperature flue gas outlet and multiple air inlets, and combustion-supporting gas is segmented into combustion reactor to ensure sufficient combustion while inhibiting NO x Pollutant generation, the high-temperature flue gas outlet is connected with post-processing device and first pipeline respectively, the first pipeline is connected with each section air inlet through branch pipeline respectively, each branch pipeline is connected with oxygen pipeline, and oxygen and high-temperature flue gas in the first pipeline form combustion-supporting gas, which is segmented into combustion reactor.The application can effectively inhibit NO x Pollutant generation while pyrolyzing and incinerating garbage, realizes clean combustion of domestic garbage, realizes efficient and reasonable conversion and utilization of each energy in garbage disposal process.

Description

Technical Field

[0001] This invention relates to the field of municipal solid waste treatment technology, and in particular to a low-NOx pyrolysis incineration system and method for municipal solid waste, which is mainly used in the fields of energy conservation, environmental protection, and resource utilization of municipal solid waste. Background Technology

[0002] Currently, the main method for urban waste disposal is incineration power generation. Incineration power generation is a harmless, volume-reducing, and resource-recovering treatment method. However, this method requires the construction of large-scale waste incineration power plants with significant equipment investment. Furthermore, it only generates benefits when processing a certain volume of waste. This method is not suitable for small-scale waste disposal.

[0003] Waste pyrolysis incineration can be applied to the treatment of relatively small-scale waste. In this method, waste pyrolysis requires a certain amount of heat, and with increasingly stringent environmental standards, NOx... x The cost of treating pollutants is also gradually increasing, among which NO... x It is a general term for N2O, NO, NO2, N2O3, N2O4, and N2O5. Although some literature has studied low-NOx waste pyrolysis combustion technology, the inventors of this application have found that most of the current research is focused on large-scale mechanical grate furnaces, emphasizing process and equipment improvements. Clean combustion has not received much attention from researchers, and no relevant reports have been found. Some literature has improved pyrolysis combustion devices, but the focus is on the realization of pyrolysis, without in-depth research on pollutant generation and / or inhibition.

[0004] For example, Chinese patent CN214891195U proposes an integrated device for pyrolysis, gasification and combustion of municipal solid waste, which includes a pyrolysis and gasification chamber, a secondary combustion chamber and a flue gas cooling chamber. The pyrolysis and gasification of waste is achieved by controlling the ventilation volume of the two combustion chambers and the furnace temperature.

[0005] Chinese patent CN216716232U proposes a high-temperature pyrolysis device for municipal solid waste, including an incinerator. The bottom of the furnace includes an ash layer and a combustion layer from bottom to top, and the furnace body includes a pyrolysis layer, a drying layer and a raw waste layer from bottom to top. The pyrolysis rate of the waste is controlled by a combustion-supporting system according to the amount of waste in the device, thereby realizing the pyrolysis and incineration of the waste.

[0006] Chinese patent CN217025869U relates to an in-furnace recirculation system for flue gas in a waste pyrolysis furnace. This system involves installing a flue gas intake pipe at the exhaust port at the top of the furnace, and using a fan to re-inject the high-temperature flue gas drawn in through the pipe back into the furnace for combustion at the bottom. Therefore, the so-called circulation in this system actually increases the residence time of the pyrolysis flue gas within the furnace, thereby improving waste treatment efficiency.

[0007] It is evident that the aforementioned literature focuses on the realization of waste pyrolysis, without conducting in-depth research on the generation or / or inhibition of pollutants, thus failing to achieve NO reduction. x Effective suppression of pollutants. Summary of the Invention

[0008] Based on the above findings and understanding, the inventors of this application have conducted further research and improvements. According to one embodiment of the present invention, the objective is to provide a low-NOx pyrolysis incineration system for municipal solid waste, which can effectively suppress NOx emissions while achieving waste pyrolysis incineration. x The generation of pollutants enables efficient and rational energy conversion and utilization during waste disposal, making it an environmentally friendly and energy-saving municipal solid waste pyrolysis incineration technology. Another objective of this invention is to provide a low-NOx pyrolysis incineration method for municipal solid waste.

[0009] The above objective can be achieved through the following technical solutions:

[0010] According to one aspect of the present invention, a low-NOx pyrolysis incineration system for municipal solid waste is provided, comprising: a pyrolysis device for pyrolyzing the waste to be treated, wherein a pyrolysis gas outlet is connected to multiple pyrolysis gas inlets of a combustion reactor via pipelines for feeding the generated pyrolysis gas into the combustion reactor in stages; and a combustion reactor comprising: multiple pyrolysis gas inlets connected to the pyrolysis device, a high-temperature flue gas outlet, and multiple air inlets; wherein the multiple air inlets are used to feed combustion-supporting gases into the combustion reactor in stages, thereby suppressing NOx while ensuring complete combustion. x The pollutant generation amount produces high-temperature flue gas; the high-temperature flue gas outlet is connected to the post-treatment device and the first pipeline respectively, the first pipeline is connected to each section air inlet via branch pipelines, and each branch pipeline is also connected to an oxygen supply pipeline, which is used to use the high-temperature flue gas entering the first pipeline as circulating flue gas, mix it with oxygen to form combustion-supporting gas, and send it into the combustion reactor through each section air inlet.

[0011] Optionally, the combustion reactor includes at least one pyrolysis gas inlet and one second pyrolysis gas inlet. The combustion reactor also includes at least one first air inlet, one second air inlet, and one third air inlet; each air inlet has at least one inlet. The first air inlet is located near the first pyrolysis gas inlet; the second air inlet is located near the second pyrolysis gas inlet.

[0012] Optionally, the first-stage pyrolysis gas inlet is located at the bottom of the combustion reactor, the second-stage pyrolysis gas inlet is located on the side of the combustion reactor, and the high-temperature flue gas outlet is located at the top of the combustion reactor. The first-stage, second-stage, and third-stage air inlets are arranged sequentially from bottom to top on the side of the combustion reactor.

[0013] Optionally, when each air inlet segment includes multiple inlets, the multiple air inlets of the same height are arranged at intervals.

[0014] Optionally, the pyrolysis device has a heat source inlet connected to the first pipe, which is used to divert some of the circulating flue gas inside the first pipe to provide the heat source required for pyrolysis.

[0015] Further optionally, the pyrolysis device also has a heat source outlet connected to a pipeline connecting the first pipeline and the branch pipeline, for mixing the heated high-temperature flue gas with the circulating flue gas about to enter the branch pipeline.

[0016] Optionally, the post-treatment device includes a waste heat boiler and a flue gas purification device in sequence, and the flue gas outlet of the flue gas purification device is connected to a chimney.

[0017] Optionally, the pipeline connected to the first pyrolysis gas inlet of the pyrolysis device is the main pipeline, and the pipeline connected to the second pyrolysis gas inlet is the secondary pipeline. Both the main pipeline and the secondary pipeline are equipped with flow control valves and flow meters. The flow control valves are used to distribute most of the pyrolysis gas to the main pipeline and the remaining small amount of pyrolysis gas to the secondary pipeline.

[0018] Optionally, each branch pipe is equipped with a flow control valve and a flow meter, which are used to control and measure the flow rate of the combustion-supporting gas entering each section's air inlet.

[0019] Optionally, the oxygen supply pipes connected to each branch pipe are equipped with oxygen supply regulating valves to regulate the oxygen content in the combustion-supporting gas at each section air inlet.

[0020] According to another aspect of the present invention, a method for low-NOx pyrolysis incineration of municipal solid waste is provided, comprising: pyrolyzing the waste to be treated using a pyrolysis device; feeding the generated pyrolysis gas into a combustion reactor in stages; and feeding combustion-supporting gas into the combustion reactor in stages, thereby suppressing NOx while ensuring complete combustion. x The pollutants are generated, and high-temperature flue gas is produced; part of the high-temperature flue gas is sent to the post-treatment device for post-treatment, and part of the high-temperature flue gas is used as circulating flue gas and mixed with oxygen as combustion-supporting gas.

[0021] Optionally, the pyrolysis gas is fed into the combustion reactor in two stages, and the combustion-supporting gas is fed into the combustion reactor in three stages.

[0022] Optionally, the first stage of pyrolysis gas is fed from the bottom of the combustion reactor, each stage of combustion-supporting gas is fed from the side of the combustion reactor, the second stage of pyrolysis gas is fed from the side of the combustion reactor, and the high-temperature flue gas is discharged from the top of the combustion reactor.

[0023] Optionally, it also includes: diverting a portion of the circulating flue gas from the first pipe to the pyrolysis device to provide the heat required for pyrolysis.

[0024] Further optionally, it also includes: after the high-temperature flue gas provides heat for pyrolysis, mixing it with the circulating flue gas that is about to enter the branch pipe, and then entering the combustion reactor through the branch pipe for reuse.

[0025] Optionally, it also includes: recovering waste heat from high-temperature flue gas, purifying the flue gas, and discharging the purified flue gas through a chimney.

[0026] Optionally, it also includes: controlling the distribution amount of each stage of pyrolysis gas entering the combustion reactor; wherein most of the pyrolysis gas is fed into the combustion reactor as first-stage pyrolysis gas for oxygen-deficient combustion; and the remaining small amount of pyrolysis gas is fed into the combustion reactor as second-stage pyrolysis gas.

[0027] Optionally, it also includes: controlling the oxygen content entering each branch pipe; and controlling the flow rate of the combustion-supporting gas entering each section air inlet.

[0028] Beneficial effects: According to one embodiment of the present invention, NO is effectively suppressed from two aspects while realizing waste pyrolysis incineration. x This method achieves clean combustion of municipal solid waste by eliminating pollutants. Specifically, a mixture of high-temperature flue gas and O2 replaces conventional air as the combustion-supporting gas, enabling the combustion of pyrolysis gas and preventing the formation of thermal NO from N2 in the air under high-temperature conditions. x The potential for pollutants, namely reducing NO during combustion at the source. x The amount of pollutants generated; in addition, by feeding pyrolysis gas and combustion-supporting gas into the combustion reactor in stages for corresponding reactions in each combustion reaction zone, the reduction zone can process the NO generated in the previous reactions. x Pollutants are reduced, further lowering NO levels. x The amount of pollutants generated was reduced, thus achieving the clean combustion of municipal solid waste.

[0029] Furthermore, when municipal solid waste is pyrolyzed in the pyrolysis unit, the heat source can be entirely derived from the high-temperature flue gas produced by the combustion reactor, eliminating the need for an external heat source. This achieves efficient and rational energy conversion and utilization during the waste disposal process, making it a green, environmentally friendly, and energy-saving municipal solid waste pyrolysis incineration process. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the connection structure of a low-NOx pyrolysis incineration system for municipal solid waste in one embodiment of the present invention.

[0031] Figure 2 This is a schematic diagram of the connection structure of a low-NOx pyrolysis incineration system for municipal solid waste in another embodiment of the present invention.

[0032] Figure 3 This is a schematic diagram of the connection structure of a low-NOx pyrolysis incineration system for municipal solid waste in another embodiment of the present invention. Detailed Implementation

[0033] The technical solution of the present invention will be clearly and completely described below with reference to embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] As mentioned above, the inventors of this application have found that current methods for waste pyrolysis incineration either focus on improving large-scale mechanical grate furnaces or emphasize the realization of pyrolysis, without in-depth research on the generation and / or inhibition of pollutants. Based on the above findings and understanding, the inventors of this application conducted further research and improvements, resulting in this invention.

[0035] Figures 1 to 3 The connection structure of the municipal solid waste low-NOx pyrolysis incineration system in several embodiments of this application is illustrated schematically. The following is in conjunction with... Figures 1 to 3 The low-NOx pyrolysis incineration system and method for municipal solid waste in the embodiments of this application will be further described.

[0036] like Figure 1 As shown in the illustration, this embodiment provides a low-NOx pyrolysis incineration system for municipal solid waste, comprising a pyrolysis unit and a combustion reactor. The pyrolysis unit has a waste inlet and a pyrolysis gas outlet, while the combustion reactor includes multiple pyrolysis gas inlets, a high-temperature flue gas outlet, and multiple air inlets. By first feeding the waste to be treated into the pyrolysis unit for pyrolysis to generate pyrolysis gas, and then feeding the generated pyrolysis gas into the combustion reactor in stages, along with combustion-supporting gases, the system ensures complete combustion while suppressing NOx emissions. x The pollutant generation amount and high-temperature flue gas are produced; and the high-temperature flue gas and oxygen are used as combustion-supporting gases to be sent in stages from multiple air inlets.

[0037] In the above embodiments, by replacing conventional air with a mixture of high-temperature flue gas and O2 as the combustion-supporting gas, and by feeding the pyrolysis gas and the combustion-supporting gas into the combustion reactor in stages for reaction, the amount of nitrogen oxides (NOx) during combustion is reduced from the source. x The amount of pollutants generated; on the other hand, by introducing pyrolysis gas and combustion-supporting gas in stages, the NO generated in the preceding reaction is effectively controlled in the reduction zone. x The reduction of pollutants further reduced NO. xThe amount of pollutants generated was reduced, thus achieving the clean combustion of municipal solid waste.

[0038] In a preferred embodiment, the pyrolysis apparatus further has a heat source inlet, and the heat source inlet is connected to the high-temperature flue gas outlet of the combustion reactor. Part of the high-temperature flue gas generated by the combustion reaction is used as the heat source required for pyrolysis. If it can be used as the entire heat source required for pyrolysis, no external heat source is needed for heating.

[0039] Furthermore, such as Figure 2 As shown, the heat source inlet can be connected to the first pipe to divert the circulating flue gas within the first pipe as a heat source. By using the high-temperature flue gas from the combustion reactor as the heat source for pyrolysis, efficient and rational energy conversion and utilization during waste disposal are achieved. The specific location of the waste inlet is not limited and can be set on one side of the pyrolysis unit for easy operation.

[0040] In a preferred embodiment, such as Figure 3 As shown, the pyrolysis device also has a heat source outlet, which is connected to a pipeline connecting the first pipeline and the branch pipeline. This allows the high-temperature flue gas, after being heated, to mix with the circulating flue gas about to enter the branch pipeline, and then enter the combustion reactor through the branch pipeline for reuse, thus achieving greater energy efficiency. The specific locations of the heat source inlet and outlet are not limited, as long as they provide a heat source for pyrolysis and are discharged. For example, a heat source zone can be set up in the pyrolysis device, with the heat source inlet and outlet located within this zone. The heat source enters this zone to provide heat for pyrolysis and is then directly discharged through the heat source zone.

[0041] Furthermore, during the staged feeding of the generated pyrolysis gas into the combustion reactor, one pipeline is designated as the main pipeline, while the rest are branch pipelines. Further, flow control valves and flow meters are installed on both the main and branch pipelines to distribute most of the pyrolysis gas (e.g., 86%–98%) to the main pipeline, which then feeds it into the combustion reactor via a first-stage pyrolysis gas inlet, allowing this majority of the pyrolysis gas to burn in the main combustion zone. The remainder is fed into the combustion reactor via a second-stage pyrolysis gas inlet. More specifically, an electric damper can be used to control the flow rate, and flow meters can be used to measure the flow rate. The specific distribution amount is not further limited and can be adjusted based on actual needs, using a primary and secondary pipeline system.

[0042] The combustion reactor in this application utilizes a portion of the high-temperature flue gas produced after the combustion reaction—specifically, the circulating flue gas from the first pipe—along with oxygen as a combustion-supporting gas, and is fed in stages. This effectively achieves NO reduction from two aspects while simultaneously realizing waste pyrolysis and incineration. x It not only suppresses pollutants but also achieves efficient and rational energy conversion and utilization during waste disposal.

[0043] Furthermore, the interior of the combustion reactor can be divided into multiple combustion reaction zones from bottom to top, such as a main combustion zone, a reduction zone, and a burnout zone. The pyrolysis gas inlet and multiple air inlets are arranged according to the sequential reaction sequence within the combustion reactor. For example, the first pyrolysis gas inlet is close to the first air inlet, placing them in the same area (main combustion zone) for oxygen-deficient combustion; the second pyrolysis gas inlet is close to the second air inlet, placing them in the same area (reduction zone) for reduction reaction, and so on. It should be noted that the combustion reaction zones are interconnected and not separated by isolation measures. The reactions proceed continuously without specific reaction boundaries. The reactions within each zone are based on the staged introduction of pyrolysis gas and combustion-supporting gas.

[0044] To improve combustion efficiency, the pyrolysis gas inlet and multiple air inlets are arranged vertically along the height of the combustion reactor. Furthermore, this application utilizes pure oxygen and high-temperature circulating flue gas from the first duct as the combustion-supporting gas, instead of conventional air. By introducing pyrolysis gas and combustion-supporting gas into the reduction zone in stages (such as second-stage pyrolysis gas and second-stage combustion-supporting gas), the NO generated in the upstream main combustion zone is effectively controlled. x The reduction of pollutants further achieves the goal of low-NOx combustion.

[0045] In this application, multiple air inlets are connected to high-temperature flue gas outlets, and oxygen supply pipes are connected to these pipes. The high-temperature flue gas, after reacting with oxygen and entering the first pipe, serves as the combustion-supporting gas, thus avoiding the addition of nitrogen elements other than those from the waste and reducing NO. x The nitrogen source that generates pollutants enables the clean combustion of municipal solid waste. For example... Figure 1 As shown, the high-temperature flue gas outlet is connected to the first duct. This first duct is then connected to each section of the air inlet via multiple branch ducts, and each branch duct is also connected to an oxygen supply duct. Furthermore, each branch duct is equipped with a flow control valve and a flow meter to control and measure the flow rate of the combustion-supporting gas entering each section of the air inlet. The oxygen supply ducts connected to each branch duct are also equipped with oxygen flow regulating valves to adjust the oxygen content in the combustion-supporting gas at each section of the air inlet. The oxygen ratio can be adjusted based on the outlet NO... X The pollutant situation is adjusted in order to reduce the export NO X The pollutant concentration is minimized; more specifically, each branch pipeline, or sub-pipeline, can regulate the gas flow rate at each location via an electric damper, and the flow rate at each location is measured by a flow meter, suppressing the formation of fuel-type NOx and thermal NOx. Furthermore, the oxygen supply pipelines connected to each sub-pipeline can also be connected to the main oxygen supply pipeline and then to the oxygen supply equipment. By controlling the oxygen content in the combustion-supporting gas in each section, the reactions within each combustion reaction zone are achieved.

[0046] Furthermore, each air inlet section can include one or more to improve reaction efficiency. Multiple inlets within each section can be arranged within the same combustion reaction zone, spaced apart along the sidewall of the combustion reactor, for example, at the same height, forming a single section. This results in a more uniform and complete reaction, further improving the reaction efficiency of the combustion reaction zone and further achieving NO control. x The effective suppression of pollutants has enabled the clean combustion of municipal solid waste.

[0047] In one specific embodiment, the combustion reactor includes two pyrolysis gas inlets and three air inlets. The first pyrolysis gas inlet is located at the bottom of the combustion reactor, the second pyrolysis gas inlet is located on one side of the combustion reactor, and the high-temperature flue gas outlet is located at the top of the combustion reactor. The first, second, and third air inlets are arranged sequentially from bottom to top on the other side of the combustion reactor to respectively supply combustion-supporting gases, namely primary air, secondary air, and burnout air. The pyrolysis gas and combustion-supporting gas supplied through the first and second pyrolysis gas inlets undergo anaerobic combustion (primary combustion zone), the pyrolysis gas and combustion-supporting gas supplied through the second and second pyrolysis gas inlets undergo a reduction reaction (reduction zone), and the combustion-supporting gas supplied through the third air inlet ensures complete combustion of the pyrolysis gas. After burnout, the flue gas is discharged from the high-temperature flue gas outlet. Part of the high-temperature flue gas is utilized as recirculated flue gas, for example, as a heat source for the pyrolysis device or as part of the combustion-supporting gas, thereby achieving efficient and rational energy conversion and utilization during waste disposal.

[0048] The following is combined with Figures 1 to 3 The illustrated low-NOx pyrolysis incineration system for municipal solid waste further illustrates the low-NOx pyrolysis incineration method for municipal solid waste in the embodiments of this application. During low-NOx pyrolysis incineration of municipal solid waste, the waste to be treated is first fed into a pyrolysis device for pyrolysis to generate pyrolysis gas; then, the pyrolysis gas is fed into the combustion reactor in stages, and the combustion-supporting gas is also fed into the combustion reactor in stages, ensuring complete combustion while suppressing NOx. x The amount of pollutants generated and the high-temperature flue gas emitted after combustion can be recycled as part of the combustion-supporting gas and a pyrolysis heat source. The specific process includes:

[0049] 1) The waste to be processed enters the pyrolysis device, is heated by a heat source and pyrolyzed to generate pyrolysis gas.

[0050] The heat source is the high-temperature flue gas discharged after the combustion reaction. The temperature of the high-temperature flue gas is typically not lower than 850°C, requiring no external heat source for heating. A portion of the high-temperature flue gas from the combustion reactor is recycled and enters the pyrolysis device through a pipeline from the heat source inlet to provide heat for pyrolysis. After heating, it mixes with the flue gas flowing out of the high-temperature flue gas outlet of the combustion reactor (i.e.,...). Figure 3 The circulating flue gas (as shown) that is about to enter the branch pipe is mixed with the gas and then enters the combustion reactor for reuse.

[0051] 2) The pyrolysis gas discharged from the pyrolysis device enters the combustion reactor in stages, and the combustion-supporting gas enters the combustion reactor in stages. The pyrolysis gas and the combustion-supporting gas are mixed in the combustion reactor to carry out a combustion reaction, producing high-temperature flue gas. A portion of the high-temperature flue gas is used as circulating flue gas and mixed with oxygen to serve as the combustion-supporting gas.

[0052] The combustion-supporting gas is a mixture of circulating flue gas produced by the combustion reactor and oxygen. The specific parameters of the oxygen supply are adjusted according to actual conditions, and are usually lower than the concentration in air (21%). The circulating flue gas mixes with the oxygen introduced through the oxygen supply pipe in the pipeline to serve as the combustion-supporting gas. In this application, oxygen is used as the combustion-supporting gas, that is, pure O2 is introduced through the oxygen supply pipe instead of air. By using the mixture of high-temperature flue gas and pure oxygen to replace conventional air as the combustion-supporting gas, NO is generated during the re-combustion reaction of N2 in the air. x This approach, by preventing the introduction of other N sources at the source, suppresses NO. x The formation of pollutants.

[0053] As described above, this application feeds the pyrolysis gas and combustion-supporting gas into the combustion reactor in stages to achieve staged combustion. Furthermore, while ensuring the orderly and efficient combustion reaction, it also achieves NO removal. x Highly effective suppression of pollutants. Specifically,

[0054] Most of the pyrolysis gas discharged from the pyrolysis unit is sent into the main combustion zone through a first-stage pyrolysis gas inlet, and some combustion-supporting gas (primary air) is injected for combustion. This is under oxygen-deficient conditions, meaning the O2 equivalence coefficient in the main combustion zone is less than 1, which suppresses NO combustion. x Pollutant generation; in addition, the high-temperature flue gas, which serves as a heat source, is mixed with the flue gas flowing out of the high-temperature flue gas outlet of the combustion reactor (which is about to enter the circulating flue gas in the branch pipeline) after heating for reuse.

[0055] Following the main combustion zone is the reduction zone, where a portion of combustion-supporting gas (secondary air) is injected, and a small amount of pyrolysis gas is simultaneously introduced through the second-stage pyrolysis gas inlet. In this zone, the NO generated in the main combustion zone is neutralized. x The pollutants were reduced, further achieving the goal of NO reduction. x Effective suppression of pollutants. This is achieved by feeding pyrolysis gas into the combustion reactor in stages. A small amount of pyrolysis gas fed through the second-stage pyrolysis gas inlet acts as a reducing gas, reducing the NO already generated in the flue gas. x Pollutants react to form N2 (through a series of complex reactions), thus reducing NO. x The role of pollutants.

[0056] Downstream of the reduction zone, a portion of combustion-supporting gas (burnout air) is injected to ensure the complete combustion of the pyrolysis gas in the combustion reactor, and high-temperature flue gas is discharged after burnout.

[0057] Of the high-temperature flue gas produced after combustion, a portion is discharged for further treatment. This involves recovering waste heat in a waste heat boiler and then purifying the flue gas in a flue gas purification device. The purified flue gas is then discharged as part of the dust collection process. The other portion is recycled as circulating flue gas. Specifically, a portion of the circulating flue gas serves as the heat source for pyrolysis in the pyrolysis unit, while the other portion (or the portion discharged after heating) combines with pure oxygen as a combustion-supporting gas and participates in the combustion reaction in stages. This not only achieves waste pyrolysis and incineration but also effectively suppresses NOx. x It reduces the generation of pollutants and achieves efficient and rational energy conversion and utilization during waste disposal, making it an environmentally friendly and energy-saving municipal solid waste pyrolysis incineration technology.

[0058] In the aforementioned pyrolysis incineration method, a mixture of pure O2 and the high-temperature circulating flue gas after combustion is used instead of conventional air as the combustion-supporting gas, thus avoiding the generation of nitrogen elements (i.e., NO) from the source. x The addition of the nitrogen source (N2) avoids the generation of thermal NO2 during the high-temperature combustion process of N2 introduced from air. x This not only ensures the possibility of combustion but also guarantees sufficient combustion and mixing of the combustion-supporting gas and the pyrolysis gas. Furthermore, both the pyrolysis gas and the combustion-supporting gas are fed into the combustion reactor in stages. The main combustion zone experiences oxygen-deficient combustion, while the reduction zone downstream of the main combustion zone reacts with the NO generated earlier. x The reduction process further enables the control of NO during the combustion reaction. x The suppression of pollutants and the burnout zone ensure the complete combustion and exhaustion of pyrolysis gas, ultimately achieving the effect of low-NOx combustion.

[0059] In one optional embodiment, the waste first enters a pyrolysis unit where it is heated and pyrolyzed into pyrolysis gas. The pyrolysis gas exiting the unit is divided into two parts, with over 90% of it serving as the main fuel and entering the combustion reactor. The high-temperature flue gas is mixed with oxygen as an auxiliary combustion gas and divided into three parts: primary air, secondary air, and burnout air, which are then fed into the combustion reactor in stages. This ensures that the primary air injected into the main combustion zone results in an oxygen-deficient reaction. In the reduction zone following the main combustion zone, secondary air and a small amount of pyrolysis gas are injected to reduce the NO generated in the main combustion zone. x The pollutants are reduced, and finally, the pyrolysis gas is fully combusted by the injection of burnout air. The combustion-supporting gas is a mixture of high-temperature circulating flue gas and O2 after the combustion reaction. Furthermore, the circulating flue gas used to heat the pyrolysis unit enters the combustion reactor and is utilized as circulating flue gas. In other words, the circulating flue gas that forms the combustion-supporting gas with oxygen can come from the high-temperature combustion reactor or from the high-temperature flue gas used to heat the pyrolysis unit.

[0060] In some of the embodiments described above, this application also has the following advantages and beneficial effects: 1) Using a mixture of high-temperature circulating flue gas and O2 to replace conventional air as the combustion-supporting gas avoids the generation of NO from N2 in the air during the combustion reaction.x 2) The staged introduction of pyrolysis gas and combustion-supporting gas controls the amount of oxygen in each combustion reaction zone, further suppressing fuel-type NO. x The generation of pollutants achieves the goal of low-NOx combustion. 3) Pyrolysis gas and combustion-supporting gas are fed into the combustion reactor in stages to achieve oxygen-deficient combustion in the main combustion zone, while the reduction zone reduces the NO generated in the main combustion zone. x The reduction and burnout air ensure the complete combustion and burnout of the pyrolysis gas, guaranteeing the low-NOx pyrolysis combustion efficiency. 4) The high-temperature flue gas after the combustion reaction is used as circulating flue gas for multiple purposes, realizing the efficient and rational conversion and utilization of energy in the waste disposal process.

[0061] The description of this invention is given for illustrative and descriptive purposes only and is not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A method for low-NOx pyrolysis incineration of municipal solid waste, characterized in that, The process is carried out using a low-NOx pyrolysis incineration system for municipal solid waste. The municipal solid waste low-NOx pyrolysis incineration system includes: The pyrolysis unit is used to pyrolyze the waste to be treated. The pyrolysis gas outlet is connected to the first pyrolysis gas inlet and the second pyrolysis gas inlet of the combustion reactor through pipelines, which are used to send the generated pyrolysis gas into the combustion reactor in two stages. The combustion reactor includes: two pyrolysis gas inlets connected to the pyrolysis unit, a high-temperature flue gas outlet, and three air inlets arranged sequentially from bottom to top on the side of the combustion reactor; wherein, the three air inlets are used to deliver the combustion-supporting gas into the combustion reactor in three stages, ensuring complete combustion while suppressing NO. x The amount of pollutants generated produces high-temperature flue gas; the high-temperature flue gas outlet is connected to the post-treatment device and the first pipeline respectively, the first pipeline is connected to each section air inlet via branch pipelines, and each branch pipeline is also connected to an oxygen supply pipeline, which is used to use the high-temperature flue gas entering the first pipeline as circulating flue gas and mix it with oxygen to form combustion-supporting gas, which is then sent into the combustion reactor through each section air inlet. The first air inlet is close to the first pyrolysis gas inlet, the second air inlet is close to the second pyrolysis gas inlet, the pipes connected to each pyrolysis gas inlet are equipped with flow control valves and flow meters, the branch pipes connected to each air inlet are equipped with flow control valves and flow meters, and the oxygen supply pipe is equipped with an oxygen supply regulating valve to regulate the oxygen content in the combustion-supporting gas of each air inlet. The method for low-NOx pyrolysis incineration of municipal solid waste includes: pyrolyzing the waste to be treated using a pyrolysis device; feeding the generated pyrolysis gas into a combustion reactor in stages; and feeding the combustion-supporting gas into the combustion reactor in stages, thereby suppressing NOx while ensuring complete combustion. x The pollutants are generated, and high-temperature flue gas is produced; part of the high-temperature flue gas is sent to the post-treatment device for post-treatment, and part of the high-temperature flue gas is used as circulating flue gas and mixed with oxygen as combustion-supporting gas. It also includes: controlling the oxygen content entering each branch pipe, controlling the flow rate of the combustion-supporting gas entering each section air inlet, and controlling the distribution of each section of pyrolysis gas entering the combustion reactor, so that most of the pyrolysis gas is sent into the combustion reactor from the first-stage pyrolysis gas inlet, and the combustion-supporting gas is introduced through the first-stage air inlet for oxygen-deficient combustion. The remaining small amount of pyrolysis gas is sent into the combustion reactor through the second-stage pyrolysis gas inlet, and the combustion-supporting gas is introduced through the second-stage air inlet for reduction reaction. The combustion-supporting gas is then sent through the third-stage air inlet to ensure complete combustion of the pyrolysis gas.

2. The method for low-NOx pyrolysis incineration of municipal solid waste according to claim 1, characterized in that, There must be at least one pyrolysis gas inlet for each section; There should be at least one air inlet in each section.

3. The method for low-NOx pyrolysis incineration of municipal solid waste according to claim 2, characterized in that, The first-stage pyrolysis gas inlet is located at the bottom of the combustion reactor, the second-stage pyrolysis gas inlet is located on the side of the combustion reactor, and the high-temperature flue gas outlet is located at the top of the combustion reactor. And / or, when each air inlet segment includes multiple inlets, the multiple inlets in each air inlet segment are arranged at intervals of the same height.

4. The method for low-NOx pyrolysis incineration of municipal solid waste according to claim 1, characterized in that, The pyrolysis device has a heat source inlet, which is connected to the first pipe and is used to divert part of the circulating flue gas in the first pipe to provide the heat source required for pyrolysis. And / or, the post-treatment device sequentially includes a waste heat boiler and a flue gas purification device, wherein the flue gas outlet of the flue gas purification device is connected to a chimney.

5. The method for low-NOx pyrolysis incineration of municipal solid waste according to claim 4, characterized in that, The pyrolysis device also has a heat source outlet, which is connected to the pipeline connecting the first pipeline and the branch pipeline, for heating the high-temperature flue gas and mixing it with the circulating flue gas that is about to enter the branch pipeline.

6. The method for low-NOx pyrolysis incineration of municipal solid waste according to claim 1, characterized in that, The first stage of pyrolysis gas is fed into the combustion reactor from the bottom, the second stage of combustion-supporting gas is fed into the combustion reactor from the side, and the high-temperature flue gas is discharged from the top of the combustion reactor.

7. The method for low-NOx pyrolysis incineration of municipal solid waste according to claim 1, characterized in that, It also includes: diverting a portion of the circulating flue gas to the pyrolysis unit to provide the heat required for pyrolysis; And / or, also includes: recovering waste heat from high-temperature flue gas, purifying the flue gas, and discharging the purified flue gas through a chimney.

8. The method for low-NOx pyrolysis incineration of municipal solid waste according to claim 7, characterized in that, It also includes: after the high-temperature flue gas provides heat for pyrolysis, it is mixed with the circulating flue gas that is about to enter the branch pipe, and then enters the combustion reactor through the branch pipe for reuse.

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