System and method for treating urban garbage based on smoldering technology

Abstract

The invention discloses a system and a method for treating urban garbage based on a smoldering technology, and belongs to the technical field of urban garbage treatment. The urban garbage treatment system comprises a garbage pretreatment device; a gradient temperature control reaction bed is arranged in the center of the garbage incinerator, and gradient temperature control is achieved through air supply and water supply; the air supply device is used for conveying air to a reaction area in the garbage incinerator so as to control the proceeding degree of the smoldering reaction; a harmful flue gas incinerator; the water treatment device is arranged between the garbage incinerator and the harmful flue gas combustion furnace, after sewage generated by garbage smoldering is treated, one part of water returns into the garbage incinerator to be mixed with air to help control the temperature in the furnace, and the other part of water enters the harmful flue gas combustion furnace to be subjected to high-temperature treatment together with harmful flue gas so as to remove harmful components; the invention discloses a multi-stage gas purification device. By means of the device system, self-sustaining smoldering decomposition treatment of the municipal solid waste is achieved.

Description

Technical Field

[0001] This invention relates to the technical field of urban waste treatment, and specifically to a system and method for treating urban waste based on smoldering technology. Background Technology

[0002] With the acceleration of urbanization and the large-scale migration of people from rural to urban areas, coupled with the increase in national consumption levels brought about by economic growth, the amount of urban waste generated is enormous. The resulting waste pollution has become a hot topic threatening the ecological environment and public health. Faced with hundreds of millions of tons of new urban waste each year, current traditional treatment methods are quite limited. Landfill accounts for about 52%, but its adverse consequences are gradually becoming apparent, causing serious leachate pollution and methane emissions. Incineration accounts for about 45%, but the unavoidable generation of dioxins and fly ash has become a bottleneck restricting the expansion of incineration scale. In addition, open dumping of waste still exists in some underdeveloped areas, causing serious environmental problems.

[0003] Therefore, finding an effective method for urban waste disposal remains an urgent issue that needs to be studied and resolved in the process of sustainable development.

[0004] Currently, the main methods for treating municipal solid waste include incineration power generation, pyrolysis gasification, and biological treatment. While incineration power generation can treat various types of waste, it requires the addition of combustion aids (such as diesel fuel consuming 0.5-1.2 L / kg of waste) and generates dioxins, resulting in high treatment costs and high energy consumption. Pyrolysis gasification requires significant investment in hardware, leading to high initial costs and potential pipeline blockages caused by the tar produced during pyrolysis, hindering later maintenance. Although biological treatment of municipal solid waste is low-carbon and environmentally friendly, its processing time of at least 15-30 days is too long, and it faces significant limitations when dealing with increasingly prevalent plastic and metal waste.

[0005] In view of this, it is indeed necessary to provide a new type of urban waste disposal system and method. Summary of the Invention

[0006] In order to solve at least one of the problems and defects existing in the prior art, the present invention provides a system and method for treating municipal waste based on smoldering technology.

[0007] In one embodiment of the present invention, wastewater generated by smoldering reaction and wastewater recovered by the waste pretreatment system are treated by a water treatment device. A portion of the treated wastewater is then transported to the waste incinerator and mixed with air supplied by an air supply device to control and maintain the smoldering reaction. Another portion of the treated wastewater is sent to a hazardous flue gas incinerator for combustion together with the hazardous flue gas incinerator, achieving effective reuse of wastewater, avoiding secondary pollution caused by wastewater, and using wastewater to control the combustion temperature of hazardous flue gas, which is conducive to the complete decomposition of harmful substances such as dioxins.

[0008] One object of the present invention is to achieve low-temperature, low-energy smoldering decomposition treatment of municipal solid waste by combining a waste pretreatment device, a waste incinerator containing a gradient temperature-controlled reaction bed, an air supply device, a harmful flue gas incinerator, a water treatment device, and a multi-stage gas purification device.

[0009] According to one aspect of the present invention, a system for treating municipal solid waste based on smoldering technology is provided, the system comprising:

[0010] A waste pretreatment device, including at least one of a crusher, a magnetic separator, a drum screen, and a dewatering press, for coarse pretreatment and sorting of waste in a landfill;

[0011] A waste incinerator, wherein a gradient temperature-controlled reaction bed is provided at the center of the waste incinerator, the gradient temperature-controlled reaction bed includes a smoldering reaction zone, in which gradient temperature is achieved through air supply and water supply;

[0012] An air supply device is used to supply air to the reaction zone inside the waste incinerator to control the extent of the smoldering reaction.

[0013] Harmful flue gas incinerators oxidize and burn harmful flue gas, turning it into harmless substances;

[0014] The water treatment unit is located between the waste incinerator and the hazardous flue gas combustion furnace. It treats the wastewater generated by the smoldering of waste. Part of the treated water is returned to the waste incinerator through pipes to mix with air to help control the temperature inside the furnace. The other part of the treated water enters the hazardous flue gas combustion furnace and is burned at high temperature together with the hazardous flue gas generated by waste incineration.

[0015] A multi-stage gas purification device includes a funnel-shaped gas collection device installed in a gradient temperature-controlled reaction bed to collect the gas generated by smoldering and transport the collected gas to the multi-stage purification device for gas purification.

[0016] Another aspect of the present invention provides a method for treating municipal solid waste based on smoldering technology, which is used in the aforementioned system for treating municipal solid waste based on smoldering technology. The method for treating municipal solid waste includes the following steps:

[0017] 1) Waste pretreatment: rough pretreatment and sorting of waste in the landfill by using at least one of the following: crusher, magnetic separator, drum screen and dewatering press;

[0018] 2) Air supply: By using an air supply device, air is supplied to the smoldering reaction zone of the gradient temperature controlled reaction bed in the waste incinerator to maintain the normal progress of the smoldering process, and the degree of smoldering reaction is controlled by controlling the flow rate of the air input.

[0019] 3) Waste incineration: In a waste incinerator, ignition inside the furnace initiates a self-sustaining smoldering reaction in the waste;

[0020] 4) Water treatment: A water treatment device is installed between the waste incinerator and the hazardous flue gas combustion furnace. The wastewater generated by the smoldering of waste is treated by the water treatment device. Part of the treated water is returned to the waste incinerator through pipelines to mix with air to help control the temperature inside the furnace. The other part of the treated water enters the hazardous flue gas combustion furnace and is treated at high temperature together with the hazardous flue gas generated by waste incineration to remove harmful components.

[0021] 5) Combustion of harmful flue gas: The harmful flue gas is oxidized and burned in the harmful flue gas combustion furnace, so that the harmful flue gas is turned into harmless substances;

[0022] 6) Multi-stage gas purification: The gas generated by the smoldering of waste is collected by connecting the gradient temperature controlled reaction bed through a multi-stage gas purification device, and then purified in multiple stages and the high-temperature synthesis gas is recovered.

[0023] The system and method for treating municipal solid waste based on smoldering technology according to embodiments of the present invention have at least one or a portion of the following advantages:

[0024] (1) By combining the waste pretreatment device, the waste incinerator with a gradient temperature control reaction bed, the air supply device, the harmful flue gas incinerator, the water treatment device and the multi-stage gas purification device, the municipal solid waste can be treated by low temperature and low energy consumption smoldering decomposition. The organic waste volume reduction rate can reach more than 85%, the dioxin emission concentration is less than 0.01ngTEQ / m³, and high calorific value syngas (>15MJ / m³) is produced simultaneously. It has the characteristics of low operating cost, simple treatment process, wide adaptability, and can treat mixed waste (including plastics, kitchen waste, textiles, etc.) without strict classification.

[0025] (2) Wastewater generated by the smoldering reaction in the waste incinerator and separated by the waste pretreatment device is treated by a water treatment device. A portion of the treated wastewater enters the waste incinerator and mixes with the air supplied by the air supply device to control and maintain the smoldering reaction of the system, thereby achieving effective utilization of wastewater and avoiding secondary pollution caused by wastewater.

[0026] (3) Another part of the treated wastewater is burned together with the harmful flue gas collected in the waste incinerator. Controlling the combustion temperature of the harmful flue gas is conducive to the full decomposition of harmful substances such as dioxins.

[0027] (4) By constructing a system consisting of a waste pretreatment device, a waste incinerator connected in series with a hazardous flue gas combustion furnace, and a multi-stage gas purification device, a low-temperature (300-500℃) smoldering decomposition process for municipal solid waste is achieved. This system can reduce the volume of organic waste by more than 85%, and the dioxin emission concentration meets the current national standard of 0.01 ng TEQ / m³. It simultaneously produces high-calorific-value syngas and can effectively recover waste heat for its own thermal reaction or for application in other fields. Compared with traditional incineration technology, energy consumption is significantly reduced, and it is suitable for the harmless treatment of mixed municipal solid waste with high moisture content. Attached Figure Description

[0028] These and / or other aspects and advantages of the present invention will become apparent and readily understood from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which:

[0029] Figure 1 This is a flowchart illustrating a method for treating municipal solid waste based on smoldering technology according to an embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram of a system for treating municipal waste based on smoldering technology according to an embodiment of the present invention. Detailed Implementation

[0031] The features of the present invention are further illustrated below through specific embodiments. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall concept of the present invention and should not be construed as a limitation thereof.

[0032] Specifically, as shown in the figure Figure 1 and Figure 2 The diagrams shown illustrate a process flow diagram and a structural diagram of a method for treating municipal waste based on smoldering technology according to an embodiment of the present invention.

[0033] First, the system 100 for treating municipal waste based on smoldering technology includes six main components: a waste pretreatment unit 10, a waste incinerator 20, an air supply unit 30, a hazardous flue gas incinerator 40, a water treatment unit 50, and a multi-stage gas purification unit 60. Of course, the system 100 for treating municipal waste does not necessarily need to include all six main components. For example, if the waste has already been pretreated, it is not necessary to include the waste pretreatment unit 10. Similarly, the hazardous flue gas incinerator 40 and the multi-stage gas purification unit 60 can also be selected in a similar manner.

[0034] The waste pretreatment device 10 includes at least one of a crusher, a magnetic separator, a drum screen, and a dewatering press for coarse pretreatment and sorting of waste in the landfill.

[0035] Specifically, a magnetic separator separates and recycles metallic waste. A drum screen separates and recycles non-flammable materials such as glass and quartz. A crusher breaks down the screened waste to a particle size suitable for smoldering. A dewatering press dehydrates the screened waste to reduce its moisture content to the level required for smoldering.

[0036] Furthermore, the wastewater after garbage dewatering enters the water treatment device 50 through pipe 11 for treatment and recycling.

[0037] The waste incinerator 20 includes components such as shell 23, feed inlet 22, and gradient temperature controlled reaction bed 21.

[0038] Specifically, the shell 23 is a heat-resistant vertical stainless steel shell, and the shell 23 is lined with a refractory ceramic fiber material; specifically, the shell 23 is designed to withstand temperatures above 1200℃.

[0039] In one example, the size of the housing 23 can be selected according to the site; for example, the size of the housing 23 is Φ3.5m×8m.

[0040] The feed inlet 22 is located on the upper part of the shell 23, corresponding to the position of the gradient temperature controlled reaction bed 21. The waste pretreated by the waste pretreatment device 10 enters the shell 23 of the waste incinerator 20 through the feed inlet 22.

[0041] The gradient temperature controlled reaction bed 21 is located at the center of the waste incinerator 20. The gradient temperature controlled reaction bed 21 includes a smoldering reaction zone, in which gradient temperature is achieved through air and water supply.

[0042] The smoldering reaction zone includes: a rotating shaft 210, at least one rotating rod 220, and a medium layer 230.

[0043] The rotating shaft 210 is located at the center of the gradient temperature controlled reaction bed 21, and at least one rotating rod 220 is spaced on the rotating shaft 210 and extends radially along the rotating shaft 210.

[0044] The medium layer 230 is configured with pores of a certain size, allowing ash and slag from the combustion of waste to pass through, while preventing unburned waste from passing through. The medium layer 230 is made of fire-resistant material. After complete combustion, the waste becomes ash and slag, where the temperature gradually decreases and it is eventually discharged as slag.

[0045] Waste pretreated by the waste pretreatment device 10 enters the shell 23 of the waste incinerator 20 through the feed inlet 22, where it is ignited in the smoldering reaction zone. During the smoldering reaction, at least one rotating rod 220 is driven by the rotating shaft 210, ensuring that the air supplied by the air supply device 30 circulates evenly within the waste and heats it uniformly. After the waste is completely burned into ash through the smoldering reaction, it is separated from the unburned waste through the medium layer 230 and finally discharged from the waste incinerator 20.

[0046] The gradient temperature-controlled reaction bed 21 inside the waste incinerator 20 can perform smoldering decomposition treatment on municipal solid waste. Wastewater generated in the smoldering reaction zone of the gradient temperature-controlled reaction bed 21 and wastewater separated from the waste pretreatment device 10 are treated. A portion of the treated wastewater is then transported to the waste incinerator 20 and mixed with air supplied by the air supply device 30 to control and maintain the smoldering reaction. The remaining treated wastewater, along with the harmful flue gas collected in the waste incinerator 20, is sent to the harmful flue gas incinerator 40 for combustion. Gas and high-temperature water vapor generated in the gradient temperature-controlled reaction bed 21 enter the water treatment device 50 and are separated. The gas is then sent to the harmful flue gas incinerator 40 for combustion, while the high-temperature water vapor is cooled in the water treatment device 50 and recycled.

[0047] The air supply device 30 includes an air compressor 31, a flow control device 32, and a duct 33.

[0048] Specifically, the conduit 33 is inserted into the gradient temperature controlled reaction bed 21 and connected to the air compressor 31 via the flow control device 32.

[0049] The conduit 33 has at least one air outlet 331 on the side of the gradient temperature controlled reaction bed 21 near the medium layer 230, which makes the air flow path in the gradient temperature controlled reaction bed 21 longer, which is conducive to the full smoldering reaction of waste at different depths.

[0050] As shown in the figure, the conduit 33 has multiple air outlets 331 disposed in the gradient temperature controlled reaction bed 21. The air outlets 331 are evenly distributed at different depths of the waste undergoing smoldering reaction in the gradient temperature controlled reaction bed 21, so that the air is more evenly distributed in the gradient temperature controlled reaction bed 21, which is conducive to the more complete smoldering reaction of waste at different depths in the gradient temperature controlled reaction bed 21 and reduces the generation of harmful smoke caused by incomplete smoldering reaction of waste.

[0051] The hazardous flue gas incinerator 40 is connected to the waste incinerator 20 via pipe 41 and to the water treatment device 50 via pipe 42. The toxic and hazardous flue gas generated during waste incineration in the gradient temperature-controlled reaction bed 21 enters the hazardous flue gas incinerator 40 via pipe 41 for further oxidation and combustion, transforming harmful substances into harmless substances. Part of the wastewater treated by the water treatment device 50 enters the hazardous flue gas incinerator 40 via pipe 42, where it is burned at high temperature together with the toxic and hazardous flue gas entering the incinerator 40 via pipe 41, removing toxic and harmful organic substances (e.g., dioxins) from its interior. The wastewater generated after high-temperature combustion mainly includes low-concentration wastewater, wet deacidification wastewater, and landfill leachate. Low-concentration wastewater can be treated and recycled using biological contact oxidation; wet deacidification wastewater can be neutralized by a multi-stage gas purification device; and given the complex organic matter and high ammonia nitrogen content of landfill leachate, a combined treatment process of "pretreatment + upflow anaerobic bioreactor + membrane bioreactor + reverse osmosis + advanced oxidation" can be used to treat it, ultimately enabling most of the organic matter in the wastewater to be degraded.

[0052] Specifically, the internal combustion conditions of the harmful flue gas incinerator 40 are generally set to burn for more than 2 seconds in a temperature range above 850°C.

[0053] A water treatment device 50 is installed between the waste incinerator 20 and the hazardous flue gas incinerator 40. The water treatment device 50 is connected to the waste incinerator 20 through pipes 51 and 52. Wastewater generated by the smoldering of waste in the gradient temperature controlled reaction bed 21 flows into the water treatment device 50 through pipe 51 for treatment. A portion of the treated wastewater flows back into the gradient temperature controlled reaction bed 21 through pipe 52. Gas and high-temperature water vapor generated by the smoldering of waste in the gradient temperature controlled reaction bed 21 are collected by a multi-stage gas purification device 60 and also flow into the water treatment device 50 through pipe 51 for treatment. The high-temperature water vapor is naturally cooled in the water treatment device 50 and circulated to the waste incinerator 20 and the hazardous flue gas incinerator 40 through pipes 52 and 42, respectively.

[0054] The multi-stage gas purification device 60 includes a funnel-shaped gas collection device 61 located inside the waste incinerator 20 and above the gradient temperature controlled reaction bed 21. This device collects the gas and high-temperature water vapor generated by the gradient temperature controlled reaction bed 21 and then transports the collected gas to the multi-stage purification device 60 through a pipeline for gas purification.

[0055] In one example, the gas collected by the funnel-shaped gas collection device 61, mixed with high-temperature water vapor, is cooled by a water treatment device 50 via pipe 51. The collected gas is then separated from the high-temperature water vapor. After combustion in the hazardous flue gas incinerator 40, the collected gas enters a multi-stage gas purification device 60 via pipe 62. The high-temperature water vapor, after being cooled by the water treatment device 50, is circulated to the waste incinerator 20 and the hazardous flue gas incinerator 40 via pipes 52 and 42, respectively.

[0056] In one example, the multi-stage gas purification device 60 also includes a cyclone dust collector for removing particulate matter and fly ash, a spray cooling device for spraying alkaline liquid to neutralize acidic gases (such as HCl, SO2, etc.), and a honeycomb activated carbon adsorption layer for adsorbing pollutants that are difficult to degrade (such as dioxins, heavy metal vapors, etc.).

[0057] Furthermore, in one example, the spray cooling device also includes an FTIR spectrometer for real-time detection of gas composition and feedback adjustment of the pH value of the spray liquid.

[0058] With the above settings, it is possible to achieve self-sustaining smoldering decomposition of municipal solid waste without the need for the addition of combustion aids, and to harmlessly treat pollutants such as sewage, harmful smoke, particulate matter, acidic gases, and dioxins generated during the treatment process.

[0059] In another embodiment of the present invention, a method for treating municipal waste based on smoldering technology is provided. The method for treating municipal waste is used in the above-mentioned system 100 for treating municipal waste based on smoldering technology. The method for treating municipal waste first performs waste pretreatment, and then achieves a self-sustaining smoldering reaction in a waste incinerator through a gradient temperature controlled reaction bed.

[0060] The method for treating municipal solid waste based on smoldering technology includes the following steps:

[0061] 1) Waste pretreatment: rough pretreatment and sorting of waste in the landfill by using at least one of the following: crusher, magnetic separator, drum screen and dewatering press;

[0062] 2) Air supply: By using the air supply device 30, air is supplied to the smoldering reaction zone of the gradient temperature controlled reaction bed 21 in the waste incinerator 20 to maintain the normal progress of the smoldering process, and the degree of smoldering reaction is controlled by controlling the flow rate of the air input.

[0063] 3) Waste incineration: In the waste incinerator 20, a self-sustaining smoldering reaction is initiated by ignition inside the furnace;

[0064] 4) Water treatment: A water treatment device 50 is installed between the waste incinerator 20 and the hazardous flue gas combustion furnace 40. The wastewater generated by the smoldering of waste is treated by the water treatment device 50. Part of the treated water is returned to the waste incinerator 20 through the pipe 52 to mix with air to help control the temperature inside the furnace. The other part of the treated water enters the hazardous flue gas combustion furnace 40 and is burned at high temperature together with the hazardous flue gas generated by waste incineration.

[0065] 5) Combustion of harmful flue gas: The harmful flue gas is oxidized and burned in the harmful flue gas combustion furnace 40, so that the harmful flue gas is turned into harmless substances;

[0066] 6) Multi-stage gas purification: The smoldering reaction zone of the gradient temperature-controlled reaction bed 21 is connected through the multi-stage gas purification device 60. The gas generated by the smoldering of the waste is collected, purified in multiple stages, and the high-temperature synthesis gas is recovered.

[0067] In step 1), a magnetic separator is used to separate metallic waste from municipal solid waste for recycling;

[0068] Use a drum screen to separate and recycle non-flammable waste such as glass and quartz;

[0069] The screened waste is crushed to a predetermined particle size that is conducive to the smoldering reaction using a crusher and a dewatering press, and then dewatered to reduce the moisture content of the waste to a level that meets the humidity requirements for the smoldering reaction.

[0070] In step 2), the air supply device 30 includes a flow control device 32 and an air compressor 31; air is supplied to the waste layer in the furnace through a duct 33 connected to the air compressor 31, and the flow rate of the air input is controlled by the flow control device 32 to control the degree of smoldering reaction.

[0071] In step 3), the waste incinerator 20 is a high-temperature resistant vertical stainless steel shell 23, and the shell 23 is lined with refractory ceramic fiber.

[0072] The domestic waste to be processed is fed into the waste incinerator 20 through the feed port of the shell 23. A rotating shaft 210 and a rotating rod 220 are set in the center of the waste incinerator 20. The rotating shaft 210 drives the rotating rod 220 to rotate, and the domestic waste is stirred during the smoldering reaction to make it heated and circulated evenly.

[0073] A gradient temperature-controlled reaction bed 21 for waste is set at the center of the waste incinerator 20. A medium layer 230 that allows ash to pass through is placed at the bottom of the gradient temperature-controlled reaction bed 21, and the ash is eventually discharged out of the furnace.

[0074] In step 5), the condition for the combustion of harmful smoke is to burn for more than 2 seconds in a temperature range above 850°C.

[0075] In step 6), the multi-stage gas purification device 60 includes a funnel-shaped gas collection device 61;

[0076] The process involves purifying the gas using a cyclone dust collector to remove particulate matter, a spray cooling device, and a honeycomb activated carbon adsorption layer, while also recovering the high-temperature syngas.

[0077] Example 1:

[0078] (1) Site selection: Find a space in a landfill in Taiyuan where the system for treating urban waste of this embodiment can be placed to carry out the waste treatment process. The space is required to have a certain area to carry out the treatment work and transport the waste.

[0079] (2) Waste pretreatment: The waste in the landfill is roughly pretreated and classified by using equipment such as crushers, magnetic separators, drum screens, and dewatering presses. The magnetic separator separates the metal waste for recycling; the drum screen separates non-flammable waste such as glass and quartz for recycling; the crusher and dewatering press are used to crush the screened waste to a certain particle size (to facilitate the smoldering reaction) and dewater it (to reduce the moisture content of the waste to the level required for the smoldering reaction).

[0080] (3) Air supply: By using an air supply device (including flow control equipment and air compressor), air is supplied to the waste layer in the furnace through a duct connected to the air compressor, thereby maintaining the normal progress of the smoldering process, and controlling the degree of smoldering reaction by controlling the flow rate of the air input.

[0081] (4) Waste Incinerator: The waste incinerator is a vertical stainless steel shell (lined with refractory ceramic fiber), with a temperature resistance of over 1200℃ and dimensions of Φ3.5m×8m (the size can be adjusted according to the site). The shell includes a feed inlet, through which pre-treated waste is fed into the waste incinerator. The waste is ignited in the furnace to initiate a self-sustaining smoldering reaction. A rotating shaft and rotating rod are installed in the center of the incinerator. On the one hand, the waste can be stirred during the smoldering reaction to ensure uniform heating. On the other hand, the air passing through can circulate evenly within the waste, keeping the entire smoldering process stable. A medium layer with a certain pore size (the ash from the waste combustion can pass through, but the waste cannot) is placed below the waste smoldering reaction zone. It is made of fireproof material. After the waste is completely burned, it becomes ash. The temperature in this area gradually decreases, and finally the ash is discharged from the furnace.

[0082] (5) Water treatment device: A water treatment device is connected between the waste incinerator and the hazardous flue gas combustion furnace. Its function is to treat the wastewater generated by the smoldering of waste in the device. Part of the water is returned to the waste incinerator through the pipeline and mixed with air to help control the temperature inside the furnace and maintain a stable self-sustaining smoldering process. The other part of the water enters the hazardous flue gas combustion furnace and is burned at high temperature together with the toxic and harmful flue gas to remove the toxic and harmful organic substances inside. The treated water can be further purified and recycled.

[0083] (6) Harmful flue gas incinerator: The toxic and harmful flue gas produced during waste incineration is further oxidized and burned in the furnace under incineration conditions, so that the harmful substances are transformed into harmless substances. The internal combustion conditions are generally set to burn for more than 2 seconds in a temperature range above 850°C.

[0084] (7) Multi-stage gas purification device: Specifically implemented as a funnel-shaped device, connected to the smoldering reaction zone, collecting the gas generated by the smoldering of garbage, and then purifying it through a cyclone dust collector (removing particulate matter), a spray cooling device (the spray material mainly uses alkaline liquid to neutralize acidic gases such as HCl and SO2 in the reaction process), and a honeycomb activated carbon adsorption layer (adsorbing dioxins, heavy metal vapors, etc.) and recovering the high-temperature synthesis gas. The main components of the high-temperature synthesis gas are various acidic gases such as HCl, SOx, HF, and NOx, as well as water. Heat is exchanged between the high-temperature synthesis gas and the low-temperature medium, thereby realizing the recovery and reuse of heat. In addition, an FTIR spectrometer is equipped to detect the gas composition in real time and adjust the pH value of the spray liquid.

[0085] The specific results of the experiment are shown in Table 1.

[0086] Table 1. Effect of smoldering treatment on waste at a landfill in Taiyuan

[0087] Organic waste volume reduction rate after treatment Dioxin emission concentration Syngas recovery rate Flue gas waste heat recovery efficiency >85% <0.01g TEQ / m³ <![CDATA[>15MJ / m 3 ]]> >75%

[0088] Example 2

[0089] (1) Site selection: The system for processing provincial and municipal waste of the present invention is installed in a corner of a small landfill in Shuozhou to facilitate the processing and transportation of waste;

[0090] (2) Waste pretreatment: The waste in the landfill is roughly pretreated and classified by using equipment such as crushers, magnetic separators, drum screens, and dewatering presses. The magnetic separator separates the metal waste for recycling; the drum screen separates non-flammable waste such as glass and quartz for recycling; the crusher and dewatering press are used to crush the screened waste to a certain particle size (to facilitate the smoldering reaction) and dewater it (to reduce the moisture content of the waste to the level required for the smoldering reaction).

[0091] (3) Air supply: By using an air supply device (including flow control equipment and air compressor), air is supplied to the waste layer in the furnace through a duct connected to the air compressor, thereby maintaining the normal progress of the smoldering process, and controlling the degree of smoldering reaction by controlling the flow rate of the air input.

[0092] (4) Waste Incinerator: The waste incinerator is a vertical stainless steel shell (lined with refractory ceramic fiber), with a temperature resistance of over 1200℃ and dimensions of Φ3.5m×8m (the size can be adjusted according to the site). The shell includes a feed inlet, through which domestic waste is fed into the waste incinerator. The waste is ignited in the furnace to initiate a self-sustaining smoldering reaction. A rotating shaft and rotating rod are installed in the center of the incinerator. On the one hand, the waste can be stirred during the smoldering reaction to ensure uniform heating. On the other hand, the air passing through can circulate evenly within the waste, keeping the entire smoldering process stable. A medium layer with a certain pore size (the ash from the waste combustion can pass through, but the waste cannot) is placed below the waste smoldering reaction zone. It is made of fireproof material. After the waste is completely burned, it becomes ash. The temperature in this area gradually decreases, and finally the ash is discharged from the furnace.

[0093] (5) Water treatment device: A water treatment device is connected between the waste incinerator and the hazardous flue gas combustion furnace. Its function is to treat the wastewater generated by the smoldering of waste in the device. Part of the water is returned to the waste incinerator through the pipeline and mixed with air to help control the temperature inside the furnace and maintain a stable self-sustaining smoldering process. The other part of the water enters the hazardous flue gas combustion furnace and is burned at high temperature together with the toxic and harmful flue gas to remove the toxic and harmful organic substances inside. The treated water can be further purified and recycled.

[0094] (6) Harmful flue gas incinerator: The toxic and harmful flue gas produced during waste incineration is further oxidized and burned in the furnace under incineration conditions, so that the harmful substances are transformed into harmless substances. The internal combustion conditions are generally set to burn for more than 2 seconds in a temperature range above 850°C.

[0095] (7) Multi-stage gas purification device: Specifically implemented as a funnel-shaped device, connected to the smoldering reaction zone, collecting the gas generated by the smoldering of garbage, and then purifying it through a cyclone dust collector (removing particulate matter), a spray cooling device (the spray material mainly uses alkaline liquid to neutralize acidic gases such as HCl and SO2 in the reaction process), and a honeycomb activated carbon adsorption layer (adsorbing dioxins, heavy metal vapors, etc.) and recovering the high-temperature syngas. The main components of the high-temperature syngas are various acidic gases such as HCl, SOx, HF, and NOx, as well as water. Heat is exchanged between the high-temperature syngas and the low-temperature medium, thereby realizing the recovery and reuse of heat. In addition, an FTIR spectrometer is equipped to detect the gas composition in real time and adjust the pH value of the spray liquid.

[0096] The specific results of the experiment are shown in Table 2.

[0097] Table 2. Smoldering treatment effect of a small landfill in Shuozhou

[0098] Organic waste volume reduction rate after treatment Dioxin emission concentration Syngas recovery rate Flue gas waste heat recovery efficiency >85% <0.01g TEQ / m³ <![CDATA[>15MJ / m 3 ]]> >75%

[0099] The system and method for treating municipal solid waste based on smoldering technology according to embodiments of the present invention have at least one or a portion of the following advantages:

[0100] (1) By combining the waste pretreatment device, the waste incinerator with a gradient temperature control reaction bed, the air supply device, the harmful flue gas incinerator, the water treatment device and the multi-stage gas purification device, the municipal solid waste can be treated by low temperature and low energy consumption smoldering decomposition. The organic waste volume reduction rate can reach more than 85%, the dioxin emission concentration is less than 0.01ngTEQ / m³, and high calorific value syngas (>15MJ / m³) is produced simultaneously. It has the characteristics of low operating cost, simple treatment process, wide adaptability, and can treat mixed waste (including plastics, kitchen waste, textiles, etc.) without strict classification.

[0101] (2) Wastewater generated by the smoldering reaction in the waste incinerator and separated by the waste pretreatment device is treated by a water treatment device. A portion of the wastewater enters the waste incinerator and mixes with the air supplied by the air supply device to control and maintain the smoldering reaction of the system, thereby achieving effective utilization of the wastewater and avoiding secondary pollution caused by the wastewater.

[0102] (3) Another part of the sewage is burned together with the harmful flue gas collected in the waste incinerator. Controlling the combustion temperature of the harmful flue gas is conducive to the full decomposition of harmful substances such as dioxins.

[0103] (4) By constructing a system consisting of a waste pretreatment device, a waste incinerator connected in series with a hazardous flue gas combustion furnace, and a multi-stage gas purification device, a low-temperature (300-500℃) smoldering decomposition process for municipal solid waste is achieved. This system can reduce the volume of organic waste by more than 85%, and the dioxin emission concentration meets the current national standard of 0.01 ng TEQ / m³. It simultaneously produces high-calorific-value syngas and can effectively recover waste heat for its own thermal reaction or for application in other fields. Compared with traditional incineration technology, energy consumption is significantly reduced, and it is suitable for the harmless treatment of mixed municipal solid waste with high moisture content.

[0104] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above-described embodiments. Those skilled in the art will understand that changes can be made to these embodiments without departing from the overall concept and spirit of the present invention, and such changes should also be considered to fall within the scope of protection of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A system for treating municipal solid waste based on smoldering technology, the system comprising: A waste pretreatment device, including at least one of a crusher, a magnetic separator, a drum screen, and a dewatering press, for coarse pretreatment and sorting of waste in a landfill; A waste incinerator, wherein a gradient temperature-controlled reaction bed is provided at the center of the waste incinerator, the gradient temperature-controlled reaction bed includes a smoldering reaction zone, in which gradient temperature is achieved through air supply and water supply; An air supply device is used to supply air to the reaction zone inside the waste incinerator to control the extent of the smoldering reaction. Harmful flue gas incinerators oxidize and burn harmful flue gas, turning it into harmless substances; The water treatment device is installed between the waste incinerator and the hazardous flue gas combustion furnace. It treats the wastewater generated by the smoldering of waste. Part of the treated water is returned to the waste incinerator through pipes to mix with air to help control the temperature inside the furnace. The other part of the treated water enters the hazardous flue gas combustion furnace and burns together with the hazardous flue gas generated by waste incineration at high temperature. A multi-stage gas purification device includes a funnel-shaped gas collection device installed in a gradient temperature-controlled reaction bed to collect the gas generated by smoldering and transport the collected gas to the multi-stage purification device for gas purification.

2. The system for treating municipal solid waste based on smoldering technology according to claim 1, characterized in that, The waste incinerator is a heat-resistant vertical stainless steel shell lined with refractory ceramic fiber. The waste incinerator is equipped with a feed inlet, through which pre-treated waste is fed into the waste incinerator. A rotating shaft and a rotating rod are set in the center of the waste incinerator. The rotating shaft drives the rotating rod to rotate, which stirs the waste during the smoldering reaction, making it heated evenly and allowing air to circulate evenly. A medium layer that allows ash and slag to pass through is set in the lower layer of the waste gradient temperature-controlled reaction bed.

3. The system for treating municipal solid waste based on smoldering technology according to claim 2, characterized in that, The air supply device includes an air compressor and a flow control device. Air is supplied to the waste incinerator through a duct connected to the air compressor, and the flow control device controls the flow rate of the air input to control the degree of smoldering reaction. The multi-stage air purification device also includes a cyclone dust collector for removing particulate matter, a spray cooler for spraying alkaline liquid, a honeycomb activated carbon adsorption layer for adsorbing dioxins and heavy metal vapors, and an FTIR spectrometer for real-time detection of gas composition and feedback adjustment of the pH value of the spray liquid.

4. A method for treating municipal solid waste based on smoldering technology, the method comprising the following steps: 1) Waste pretreatment: rough pretreatment and sorting of waste in the landfill by using at least one of the following: crusher, magnetic separator, drum screen and dewatering press; 2) Air supply: By using an air supply device, air is supplied to the smoldering reaction zone of the gradient temperature controlled reaction bed in the waste incinerator to maintain the normal progress of the smoldering process, and the degree of smoldering reaction is controlled by controlling the flow rate of the air input. 3) Waste incineration: In a waste incinerator, ignition inside the furnace initiates a self-sustaining smoldering reaction in the waste; 4) Water treatment: A water treatment device is installed between the waste incinerator and the hazardous flue gas combustion furnace. The wastewater generated by the smoldering of waste is treated by the water treatment device. Part of the treated water is returned to the waste incinerator through pipelines to mix with air to help control the temperature inside the furnace. The other part of the treated water enters the hazardous flue gas combustion furnace and is burned at high temperature together with the hazardous flue gas generated by waste incineration. 5) Combustion of harmful flue gas: The harmful flue gas is oxidized and burned in the harmful flue gas combustion furnace, so that the harmful flue gas is turned into harmless substances; 6) Multi-stage gas purification: The gas generated by the smoldering of waste is collected by connecting the gradient temperature controlled reaction bed through a multi-stage gas purification device, and then purified in multiple stages and the high-temperature synthesis gas is recovered.

5. The method for treating municipal solid waste based on smoldering technology according to claim 4, characterized in that, In step 1), a magnetic separator is used to separate metallic waste from municipal solid waste for recycling; Use a drum screen to separate and recycle non-flammable waste such as glass and quartz; The screened waste is crushed to a predetermined particle size that is conducive to the smoldering reaction using a crusher and a dewatering press, and then dewatered to reduce the moisture content of the waste to a level that meets the humidity requirements for the smoldering reaction.

6. The method for treating municipal solid waste based on smoldering technology according to claim 4, characterized in that, In step 2), the air supply device includes a flow control device and an air compressor; air is supplied to the waste layer in the furnace through a duct connected to the air compressor, and the flow rate of the air input is controlled by the flow control device to control the degree of smoldering reaction.

7. The method for treating municipal solid waste based on smoldering technology according to claim 4, characterized in that, In step 3), the waste incinerator is a high-temperature resistant vertical stainless steel shell, and the shell is lined with refractory ceramic fiber. The waste to be processed is fed into the waste incinerator through the feed port of the shell. A rotating shaft and a rotating rod are set in the center of the waste incinerator. The rotating shaft drives the rotating rod to rotate, which stirs the domestic waste during the smoldering reaction, so that it is heated evenly and the air is circulated evenly.

8. The method for treating municipal solid waste based on smoldering technology according to claim 7, characterized in that, A gradient temperature-controlled reaction bed for waste is set at the center of the waste incinerator. A medium layer that allows ash to pass through is placed at the bottom of the gradient temperature-controlled reaction bed, and the ash is eventually discharged out of the furnace.

9. The method for treating municipal solid waste based on smoldering technology according to claim 4, characterized in that, In step 5), the condition for the combustion of harmful smoke is to burn for more than 2 seconds in a temperature range above 850°C.

10. The method for treating municipal solid waste based on smoldering technology according to claim 4, characterized in that, In step 6), the multi-stage gas purification device includes a funnel-shaped gas collection device; The process involves purifying the gas using a cyclone dust collector to remove particulate matter, a spray cooling device, and a honeycomb activated carbon adsorption layer, while also recovering the high-temperature syngas.

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