System and method for coupling anaerobic pyrolysis upgrading of household garbage with cement kiln

Abstract

The invention discloses a system and method for coupling anaerobic pyrolysis and upgrading of household garbage with a cement kiln, and belongs to the technical field of alternative fuels for cement production. The system comprises a garbage drying pyrolysis system, a cement kiln system and a bypass ventilation system, the garbage pyrolysis system is mainly used for producing high-quality high-chlorine-containing garbage carbon after garbage reduction treatment, and the produced garbage carbon has a flexible operation mode, can be stored in a coal storage bunker and can also be directly conveyed into a rotary kiln. Wherein the drying furnace is responsible for carrying out pre-drying treatment on garbage and removing moisture; the pyrolyzing furnace receives the dried garbage and executes a pyrolyzing procedure; the cement kiln system can produce cement clinker by using the garbage carbon; the bypass ventilation system aims at treating high-temperature chlorine-containing flue gas generated by the rotary kiln, reducing coking and corrosion at positions such as a decomposing furnace and a suspension preheater, and prolonging the service life of equipment. According to the invention, efficient resource upgrading utilization of the household garbage can be realized, the operation mode is flexible, and continuous treatment of the garbage can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of alternative fuels for cement production, and relates to a system and method for anaerobic pyrolysis and upgrading of domestic waste coupled with a cement kiln. Background Art

[0002] Globally, climate change and energy crisis are becoming increasingly urgent. As an important area of ​​energy consumption and carbon dioxide emissions, the cement industry is in urgent need of technological innovation and industrial upgrading. In this context, the application of alternative fuel technology in the cement industry has become particularly important as a key technical path to reduce pollution and carbon emissions. In particular, the coordinated treatment of municipal solid waste (MSW) by cement kilns as a comprehensive solution for waste management and energy recovery has attracted widespread attention in the industry.

[0003] At present, the mainstream process methods are mainly divided into two technical routes: sorting and gasification / incineration. However, the existing external pre-combustion furnace technology has several limitations. For example, when the grate furnace is processing unsorted raw garbage, the combustion efficiency is insufficient, resulting in the thermal burn-off rate of the discharged bottom ash exceeding expectations; the stepped grate incinerator has limited adaptability to the physical form and calorific value changes of the garbage, especially when processing wastes such as fine particulate matter and low-melting point plastics. Although the hot plate furnace can adapt to wastes of different forms and calorific values, its operating technology requirements are high and it is easily affected by fluctuations in garbage composition, which may lead to reduced combustion efficiency and increased difficulty in pollution control. In addition, the traditional external pre-combustion furnace cannot be operated independently during the non-operation period of the cement kiln, and cannot solve the continuous treatment needs of domestic waste.

[0004] In view of this, the development of an efficient, flexible and economical cement kiln waste-combustion technology and system is of great practical significance for achieving effective waste management, improving energy recovery efficiency and reducing environmental pollution. The technology and system must be able to adapt to the fluctuation of waste composition, ensure combustion efficiency and pollution control, and be able to operate independently during the non-operation period of the cement kiln to ensure the continuity of domestic waste treatment. Summary of the invention

[0005] The purpose of the present invention is to provide a system and method for anaerobic pyrolysis and upgrading of domestic waste coupled with a cement kiln, so as to solve the technical problems that the prior art is difficult to adapt to fluctuations in waste composition, has low combustion efficiency, and discontinuous waste treatment.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a system for anaerobic pyrolysis and upgrading of domestic waste coupled with a cement kiln, comprising: A garbage drying and pyrolysis system, the garbage drying and pyrolysis system comprising a garbage storage tank, a feeder, a conveying device, a drying furnace, a pyrolysis furnace and a coal storage bin; the domestic garbage in the garbage storage tank is fed by the feeder through the conveying device, the drying furnace and the pyrolysis furnace in sequence to generate garbage charcoal, and the outlet of the pyrolysis furnace is respectively connected to the coal storage bin and the cement kiln system; A cement kiln system, the cement kiln system comprising a conveyor, a suspension preheater, a decomposition furnace, a smoke chamber and a rotary kiln connected in sequence; the rotary kiln is respectively connected to the outlets of a grate cooler and a pyrolysis furnace; the smoke chamber is connected to a bypass venting system; A bypass ventilation system comprises a cooling fan, a quenching air mixing chamber, a second dust collector, a second induced draft fan and a chimney which are sequentially connected through pipelines; the cooling fan is connected to the smoke chamber.

[0007] Furthermore, the garbage drying and pyrolysis system also includes a hot blast furnace; the inlet and outlet of the hot blast furnace are both connected to the pyrolysis furnace, and the pyrolysis oil and gas in the pyrolysis furnace are burned in the hot blast furnace to generate high-temperature flue gas which is passed into the pyrolysis furnace.

[0008] Furthermore, the garbage drying and pyrolysis system also includes a waste heat boiler; the waste heat boiler is connected to the drying furnace and the pyrolysis furnace respectively.

[0009] Furthermore, the suspension preheater is also connected to a first induced draft fan and a first dust collector in sequence; the first dust collector is connected to the drying furnace.

[0010] Furthermore, the garbage storage tank is directly connected to the rotary kiln through a pipeline, and the leachate in the garbage storage tank can participate in the combustion in the rotary kiln.

[0011] Furthermore, the cement kiln system also includes a tertiary air duct; one end of the tertiary air duct is connected to the grate cooler, and the other end is connected to the smoke chamber.

[0012] Furthermore, an air cooler is provided between the quenching air mixing chamber and the second dust collector.

[0013] Furthermore, a first safety valve is provided on the connecting pipeline between the smoke chamber and the cooling fan; and a second safety valve is provided on the connecting pipeline between the second dust collector and the second induced draft fan.

[0014] Furthermore, the second dust collector is a bag dust collector; and the feeder is a plate feeder.

[0015] In a second aspect, the present invention provides a method for coupling anaerobic pyrolysis and upgrading of domestic waste to a cement kiln, based on the above-mentioned system for anaerobic pyrolysis and upgrading of domestic waste to a cement kiln, comprising the following steps: The domestic garbage in the garbage storage tank is transported to the drying furnace for pre-drying to remove moisture; then it is pyrolyzed in the pyrolysis furnace at a temperature of 400℃~500℃ to generate garbage charcoal containing high chlorine, which enters the rotary kiln or is stored in the coal storage bunker; The cement raw material passes through the suspension preheater, the decomposition furnace and the smoke chamber, and then enters the rotary kiln, where it is burned with garbage charcoal at a temperature of 1300°C to 1500°C to obtain cement clinker; the cement clinker enters the grate cooler for cooling; at the same time, the smoke generated in the rotary kiln is gathered in the smoke chamber; The flue gas in the smoke chamber flows into the bypass exhaust system, is mixed with cold air in the quenching air mixing chamber 20 through the cooling fan, and then passes through the second dust collector to produce chlorine crystals from harmful components in the gas, and is finally discharged to the chimney through the second induced draft fan.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a system and method for anaerobic pyrolysis and upgrading of domestic waste coupled with a cement kiln. The front-end waste drying and pyrolysis system can operate independently or work in coordination with the back-end cement kiln system to ensure the continuity of domestic waste treatment during the non-operating cycle of the cement kiln, thereby effectively solving the problem of interruption of waste treatment during the staggered shutdown period of the cement kiln. In addition, the drying furnace realizes the supply of heat energy to the waste by recycling and utilizing the low-temperature flue gas discharged by the suspension preheater. In the pyrolysis furnace, the pyrolysis oil and gas generated by the anaerobic pyrolysis process are transported to the hot blast furnace for combustion, and the generated high-temperature flue gas provides heat energy for the pyrolysis furnace, which significantly improves the energy utilization efficiency of the entire system, and has strong flexibility and stability.

[0017] Furthermore, the present invention can process garbage in a clean, green and efficient manner, significantly reducing dioxin emissions. The garbage pretreatment system is an anaerobic cracking system, which not only eliminates oxidation reactions, but also reduces the generation of dioxin precursors. First, the heavy metal copper and iron in the garbage do not have the conditions for high-temperature oxidation, and are not easy to become catalysts that promote the generation of dioxins, thereby reducing the generation of dioxins from the source. Secondly, the garbage charcoal is input from the rotary kiln head for combustion, and the high-temperature alkaline environment in the rotary kiln can inhibit the generation of dioxins, achieving dual control of dioxin emissions. Finally, the bypass venting system quickly cools the high-chlorine flue gas, reduces the temperature range in which dioxins are easily generated by the high-chlorine flue gas, blocks the re-synthesis path of dioxins, and reduces the final emission of dioxins.

[0018] Furthermore, the present invention has a high fuel substitution rate and little impact on the quality of clinker. The present invention has strong adaptability to household garbage of various shapes, sizes, and calorific values, and can process a variety of wastes. After the garbage is dried and pyrolyzed, its combustion properties are improved, and the reduction of garbage is also achieved. After the garbage charcoal is put into the furnace, it can achieve stable combustion in the rotary kiln furnace without being affected by the fluctuation of garbage composition. The present invention adds bypass ventilation facilities to remove harmful elements such as chlorine and sulfur enriched in the garbage charcoal, which improves the combustion efficiency while ensuring the environmental safety of clinker production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 This is a schematic diagram of the system structure of an anaerobic pyrolysis and upgrading of domestic waste coupled with a cement kiln according to the present invention.

[0021] Among them: 1-garbage storage tank; 2-feeder; 3-conveying device; 4-drying furnace; 5-waste heat boiler; 6-pyrolysis furnace; 7-hot blast furnace; 8-coal storage bin; 9-grate cooler; 10-tertiary air duct; 11-rotary kiln; 12-first dust collector; 13-conveyor; 14-first induced draft fan; 15-suspension preheater; 16-decomposition furnace; 17-smoke chamber; 18-first safety valve; 19-cooling fan; 20-quenching mixing chamber; 21-air cooler; 22-second dust collector; 23-second safety valve; 24-second induced draft fan; 25-chimney. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0025] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0026] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0027] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings: See also Figure 1The embodiment of the present invention discloses a system for anaerobic pyrolysis and upgrading of domestic waste coupled with a cement kiln, comprising a waste drying and pyrolysis system, a cement kiln system and a bypass ventilation system; the waste drying and pyrolysis system comprises a waste storage tank 1, a feeder 2, a conveying device 3, a drying furnace 4, a pyrolysis furnace 6 and a coal storage bin 8; the feeder 2 is preferably a plate feeder but is not limited to; the domestic waste in the waste storage tank 1 passes through the conveying device 3, the drying furnace 4 and the pyrolysis furnace 6 in sequence through the feeder 2 to generate waste charcoal, and the outlet of the pyrolysis furnace 6 is connected to the coal storage bin 8 and the water tank 8 respectively. Cement kiln system; the cement kiln system includes a conveyor 13, a suspension preheater 15, a decomposition furnace 16, a smoke chamber 17 and a rotary kiln 11 connected in sequence; the rotary kiln 11 is respectively connected to the outlets of the grate cooler 9 and the pyrolysis furnace 6; the smoke chamber 17 is connected to a bypass venting system; the bypass venting system includes a cooling fan 19, a quenching air mixing chamber 20, a second dust collector 22, a second induced draft fan 24 and a chimney 25 connected in sequence through pipelines; the cooling fan 19 is connected to the smoke chamber 17; the second dust collector 22 preferably adopts but is not limited to a bag dust collector.

[0029] In this embodiment, the garbage pyrolysis system is mainly used to produce high-quality garbage charcoal with high chlorine content after garbage reduction treatment. The generated garbage charcoal has a flexible operation mode and can be stored in the coal storage bin 8 or directly transported to the rotary kiln 11. Among them, the drying furnace 4 is responsible for pre-drying the garbage and removing moisture; the pyrolysis furnace 6 receives the dried garbage and performs the pyrolysis procedure; the temperature of the pyrolysis furnace 6 is controlled at 400-500°C, which can effectively ensure that most of the chlorine in the garbage remains in the garbage charcoal, and at the same time, anaerobic cracking effectively curbs the occurrence of oxidation reactions and significantly reduces the production of dioxin precursors. In addition, due to the lack of a high-temperature oxidation environment, heavy metals such as copper and iron in the garbage cannot act as catalysts to promote the formation of dioxins, thereby reducing the generation of dioxins at the source. In addition, since the garbage is dried by the drying furnace 4, the H2O and CO2 in the pyrolysis oil and gas produced by the pyrolysis furnace 6 are reduced, and it does not contain chlorine, and has a higher calorific value. In the cement kiln system of this embodiment, the rotary kiln 11 can cleanly utilize the heat of high-chlorine garbage charcoal while inhibiting the generation of dioxins; the temperature of the rotary kiln 11 is generally 1300-1500°C, and it is a high-alkali environment, which can basically inhibit the generation of dioxins and ensure that most of the chlorine in the rotary kiln 11 is in the flue gas; on the other hand, the high-chlorine flue gas is directly cooled and dusted through the bypass venting system, and does not enter the upper decomposition furnace 16 and preheater of the cement kiln, ensuring the safety and service life of the entire system. The bypass venting system is designed to treat the high-temperature chlorine-containing flue gas generated by the rotary kiln 11, reduce coking and corrosion in the decomposition furnace 16, suspension preheater 15 and other locations, and extend the service life of the equipment.

[0030] In a feasible embodiment of the present invention, the garbage drying and pyrolysis system further includes a hot blast furnace 7 and a waste heat boiler 5; the inlet and outlet of the hot blast furnace 7 are both connected to the pyrolysis furnace 6, the pyrolysis oil and gas in the pyrolysis furnace 6 are burned in the hot blast furnace 7, and the high-temperature flue gas generated is passed into the pyrolysis furnace 6. The waste heat boiler 5 is connected to the drying furnace 4 and the pyrolysis furnace 6 respectively. The hot blast furnace 7 is responsible for burning the pyrolysis oil and gas generated by the pyrolysis furnace, and can provide high-quality high-temperature flue gas for system heating, and the excess high-temperature flue gas is passed into the waste heat boiler 5 for utilization.

[0031] In a feasible embodiment of the present invention, the suspension preheater 15 is also connected to the first induced draft fan 14 and the first dust collector 12 in sequence; the first dust collector 12 is connected to the drying furnace 4. The rotary kiln 11 can cleanly utilize the heat of the garbage charcoal containing high chlorine while inhibiting the generation of dioxins; the low-temperature flue gas at the uppermost outlet of the suspension preheater 15 can be used for drying the garbage in the drying furnace.

[0032] In a feasible embodiment of the present invention, the garbage storage tank 1 is also directly connected to the rotary kiln 11 through a pipeline, and the leachate in the garbage storage tank 1 is sent to the rotary kiln 11 for combustion and cleaning treatment.

[0033] In a feasible embodiment of the present invention, the cement kiln system further includes a tertiary air duct 10; one end of the tertiary air duct 10 is connected to the grate cooler 9, and the other end is connected to the smoke chamber 17. The flue gas cooled by the grate cooler 9 enters the tertiary air duct 10 and returns to the smoke chamber 17 to provide oxygen for combustion in the decomposition furnace 16.

[0034] In a feasible embodiment of the present invention, an air cooler 21 is further provided between the quenching air mixing chamber 20 and the second dust collector 22. A first safety valve 18 is provided on the connecting pipeline between the smoke chamber 17 and the cooling fan 19; a second safety valve 23 is provided on the connecting pipeline between the second dust collector 22 and the second induced draft fan 24. The cooling fan 19 and the quenching air mixing chamber 20 are used to quickly cool the high-chlorine flue gas, reduce the temperature range where dioxins are easily generated in the high-chlorine flue gas, block the resynthesis path of dioxins, and thus reduce the emission of dioxins. The second dust collector 22 collects the high-chlorine and alkaline flue gas and generates chlorine crystals after cooling down.

[0035] The embodiment of the present invention discloses a method for coupling anaerobic pyrolysis and upgrading of domestic waste to a cement kiln. Based on the above-mentioned system for anaerobic pyrolysis and upgrading of domestic waste to a cement kiln, the method comprises the following steps: The domestic waste in the waste storage tank 1 is transported to the drying furnace 4 for pre-drying to remove moisture; then the waste is pyrolyzed in the pyrolysis furnace 6 at a temperature of 400°C to 500°C to generate waste charcoal containing high chlorine, which enters the rotary kiln 11 or is stored in the coal storage bin 8; The cement raw material passes through the suspension preheater 15, the decomposition furnace 16 and the smoke chamber 17, and enters the rotary kiln 11, where it is burned with garbage charcoal at a temperature of 1300°C to 1500°C to obtain cement clinker; the cement clinker enters the grate cooler 9 for cooling; at the same time, the smoke generated in the rotary kiln 11 is gathered in the smoke chamber 17; The flue gas in the smoke chamber 17 flows into the bypass exhaust system, is mixed with cold air in the quenching air mixing chamber 20 through the cooling fan 19, and then passes through the second dust collector 22 to produce chlorine crystals from harmful components in the gas, and is finally discharged to the chimney 25 through the second induced draft fan 24.

[0036] The working principle of the present invention is as follows: See also Figure 1 In this system, the medium flows from top to bottom and from left to right. Along the medium flow direction, the front-end system mainly includes the garbage low-temperature drying section and the anaerobic pyrolysis section, and the drying and dehydration process is added. The drying furnace 4 uses the low-temperature flue gas (280-320℃) output from the C1 outlet of the extraction suspension preheater 15 for heating; when the pyrolysis furnace 6 performs anaerobic pyrolysis to treat the garbage, the proportion of H2O and CO2 in the pyrolysis gas is reduced, and the calorific value of the pyrolysis oil and gas is higher; the pyrolysis oil and gas generated by pyrolysis is burned in the hot blast furnace 7, and the high-temperature flue gas generated is used to heat the pyrolysis furnace 6. In the process of high-temperature heating of the garbage to make it thermally cracked, not only the oxidation reaction is eliminated, but also the generation of dioxin precursors is reduced, which fundamentally inhibits the generation of dioxins. At the same time, since the heavy metal copper and iron in the garbage do not have the conditions for high-temperature oxidation, it is not easy to become a catalyst that promotes the generation of dioxins, so it can be said that the generation of dioxins is eliminated from the source.

[0037] The garbage charcoal produced by the pyrolysis furnace 6 is directly input from the kiln head of the rotary kiln 10, which improves the energy utilization efficiency and reduces the energy consumption and pollution in the material transportation process. Preferably, a coal storage bunker 8 is set between the pyrolysis furnace 6 and the rotary kiln 10. This intermediate storage link provides operational flexibility, allowing the garbage drying and pyrolysis system to operate independently when the cement kiln is shut down at off-peak hours. In this way, even if there is a break in the cement production process, the garbage treatment will not be interrupted, ensuring the continuity and efficiency of the garbage treatment, and the pyrolysis furnace 6 converts the garbage into valuable garbage charcoal. This process not only achieves the reduction of garbage, but also ensures the harmlessness of garbage treatment through high-temperature pyrolysis technology. And on this basis, the potential for resource utilization is increased. At the same time, it improves energy utilization efficiency and environmental friendliness.

[0038] The calorific value of the garbage char generated by pyrolysis is high. It is burned in the rotary kiln 11 to directly heat the cement kiln, and the coal-saving effect is more significant. At the same time, in the rotary kiln 11, HCl will be oxidized to a chlorine source (active chlorine atoms, chlorine gas) at high temperature. The alkaline substances such as CaO contained in the cement clinker can absorb HCl, thereby inhibiting the formation of PCDF / PCDD. The high temperature environment in the rotary kiln 11 allows dioxins and their precursors to be effectively decomposed. The cooling fan 19 is used to rapidly cool the flue gas quenching and mixing chamber 20, which can effectively avoid the resynthesis of dioxin-like substances. The heavy metals in the garbage char generated by pyrolysis enter the cement kiln calcination system, are solidified in the clinker, and finally solidified in the concrete products, and will not precipitate. The leachate in the garbage storage tank 1 can also be sent to the rotary kiln 11 for combustion and utilization.

[0039] An air outlet is set at the kiln tail smoke chamber 17 to extract the gas containing high concentration of Cl- elements, and cold air is mixed into the quenching air mixing chamber 20 through the cooling fan 19. Preferably, compared with the conventional bypass venting system, the present invention adds an air cooler 21 to quickly cool the flue gas. In this system, the flue gas temperature after the quenching air mixing chamber can be reduced to 400°C, and then reduced to 150°C through the air cooler. Studies have shown that maintaining the temperature of the post-combustion gas purification system below 200°C will achieve a better control effect on dioxins. By adding the cooling fan 19 and the quenching air mixing chamber 20, the flue gas temperature is quickly reduced to below 150°C. The cooled flue gas passes through the second dust collector 22, so that the harmful components such as alkali and chlorine in the gas produce chlorine crystals, which are collected by the dust collector. The gas after dust removal meets the emission standards or is sent to the inlet of the high-temperature fan 24 at the kiln tail, and the flue gas of the kiln tail system is discharged from the chimney 25 after purification.

[0040] Embodiment 1: The system and method provided by the present invention are applied to a cement production line with a clinker output of 6000t / d and a garbage processing capacity of 300t / d. Preferably, the drying furnace 4 is designed to receive wet garbage and perform drying and dehydration treatment, and the operating temperature is controlled at 150-200°C to remove about 30% of the moisture in the garbage; the pyrolysis furnace 6 is designed to receive the dried garbage and perform anaerobic pyrolysis treatment. The operating temperature of the pyrolysis furnace 6 is set at 400-500°C to ensure that the garbage is effectively pyrolyzed in an oxygen-deficient environment; during the pyrolysis process, it is estimated that each ton of wet domestic garbage can produce about 150 kg of garbage charcoal, with a calorific value of about 4000-5000 kcal / kg; the rotary kiln 11 is designed to receive the garbage charcoal output by the pyrolysis furnace 6, and the temperature in the kiln is maintained at 1400-1600°C to ensure that the pyrolysis charcoal is completely burned and the generation of dioxins is inhibited; the bypass venting system is designed to treat the high-temperature chlorine-containing flue gas generated by the rotary kiln 11, and the operating temperature is controlled at 150-250°C to reduce coking and corrosion in the furnace. Preferably; during the operation of the system, through high-temperature pyrolysis and alkaline environment, the dioxin emission is reduced to less than 0.1 ng / m3, which is far below the international standard. It is expected to replace about 20% of coal consumption and reduce carbon dioxide emissions by about 30%.

[0041] Embodiment 2: In a cement production line with a clinker output of 6000t / d and a garbage processing capacity of 300t / d, the system and method provided by the present invention are applied. Unlike Example 1, during the peak-shifting shutdown period of the cement kiln, the front-end drying and pyrolysis system of the present invention can independently process 300-350 tons of domestic garbage per day. The garbage charcoal is stored in the charcoal storage bin. The garbage charcoal in the charcoal storage bin is used as an auxiliary fuel, which can not only reduce the dependence on traditional fuels, but also reduce production costs.

[0042] Embodiment three: In the system of this embodiment, the drying section extracts part of the flue gas from the waste heat boiler from the drying furnace 4, and performs garbage drying treatment by countercurrent heating. Specifically, low-temperature flue gas (about 280-320°C) enters the drying furnace 4 from the waste heat boiler, forming a countercurrent heating effect with the wet garbage. The advantage of countercurrent heating is that during the garbage drying process, there is less direct contact between water vapor and flue gas, which makes the discharge of water vapor cleaner and avoids mixing with harmful components. In addition, due to the large temperature difference at the wet garbage end of countercurrent heating, the utilization rate of thermal energy can be effectively improved. The water vapor generated during the drying process is collected and condensed, and the condensed water enters the cooling tower for further purification; the treated flue gas directly enters the exhaust gas treatment system, including the cooling fan 19, the quenching air mixing chamber 20 and the second dust collector 22, to remove harmful substances such as chlorine crystals, and finally sent to the chimney through the induced draft fan to meet the emission standards.

[0043] Through the countercurrent heating process, the system can achieve an efficient combination of garbage drying and flue gas purification, ensuring the clean discharge of moisture and flue gas, while effectively improving drying efficiency and reducing energy consumption.

[0044] Embodiment 4: In the system of this embodiment, the drying section extracts part of the flue gas from the waste heat boiler from the drying furnace 4 and performs garbage drying in a downstream heating manner. The characteristic of downstream heating is that the flue gas and the garbage flow in the same direction, which has the following specific advantages: High heat transfer efficiency: In the initial stage of co-current heating, the temperature difference between the flue gas and the garbage is large, and the heat transfer rate is high, which is conducive to rapid dehydration.

[0045] Reduced coking of equipment: Since the moisture in the garbage is in contact with the flue gas for a shorter time, the particle deposition in the flue gas is reduced, reducing the risk of coking and clogging of the equipment.

[0046] During the drying process, the steam and flue gas generated downstream enter the tail gas treatment system through the pipeline. The tail gas is first cooled by the cooling fan 19, and then enters the quenching air mixing chamber 20, where the temperature is quickly reduced to below 150°C by adding cold air. The cooled tail gas passes through the second dust collector 22 to remove chlorine crystals and suspended particles. After meeting the standards, it is discharged or sent to the tail of the rotary kiln and combined with the flue gas from other systems to ensure the environmental protection and safety of the entire system.

[0047] The downstream heating method optimizes the utilization path of flue gas, which can quickly dry the garbage while avoiding secondary pollution, thus ensuring the continuous and efficient operation of the system.

[0048] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A system for anaerobic pyrolysis and upgrading of domestic waste coupled with a cement kiln, characterized in that: include: A garbage drying and pyrolysis system, the garbage drying and pyrolysis system comprising a garbage storage tank (1), a feeder (2), a conveying device (3), a drying furnace (4), a pyrolysis furnace (6) and a coal storage bin (8); domestic garbage in the garbage storage tank (1) is sequentially passed through the conveying device (3), the drying furnace (4) and the pyrolysis furnace (6) by the feeder (2) to generate garbage charcoal, and the outlet of the pyrolysis furnace (6) is respectively connected to the coal storage bin (8) and the cement kiln system; A cement kiln system, the cement kiln system comprising a conveyor (13), a suspension preheater (15), a decomposition furnace (16), a smoke chamber (17) and a rotary kiln (11) connected in sequence; the rotary kiln (11) is respectively connected to the outlets of a grate cooler (9) and a pyrolysis furnace (6); the smoke chamber (17) is connected to a bypass venting system; A bypass ventilation system, the bypass ventilation system comprising a cooling fan (19), a quenching air mixing chamber (20), a second dust collector (22), a second induced draft fan (24) and a chimney (25) connected in sequence through pipelines; the cooling fan (19) is connected to the smoke chamber (17).

2. According to claim 1, a system for anaerobic pyrolysis and upgrading of domestic waste coupled with a cement kiln is characterized in that: The garbage drying and pyrolysis system further comprises a hot blast furnace (7); the inlet and outlet of the hot blast furnace (7) are both connected to the pyrolysis furnace (6); the pyrolysis oil gas in the pyrolysis furnace (6) burns in the hot blast furnace (7) and generates high-temperature flue gas which is passed into the pyrolysis furnace (6).

3. According to claim 2, a system for anaerobic pyrolysis and upgrading of domestic waste coupled with a cement kiln is characterized in that: The garbage drying and pyrolysis system further comprises a waste heat boiler (5); the waste heat boiler (5) is respectively connected to the drying furnace (4) and the pyrolysis furnace (6).

4. The system of anaerobic pyrolysis and upgrading of domestic waste coupled with cement kiln according to claim 1 is characterized in that: The suspension preheater (15) is also connected in sequence to a first induced draft fan (14) and a first dust collector (12); the first dust collector (12) is connected to the drying furnace (4).

5. The system of anaerobic pyrolysis and upgrading of domestic waste coupled with cement kiln according to claim 1 is characterized in that: The garbage storage tank (1) is also directly connected to the rotary kiln (11) via a pipeline, and the leachate in the garbage storage tank (1) can participate in combustion in the rotary kiln (11).

6. The system of anaerobic pyrolysis and upgrading of domestic waste coupled with cement kiln according to claim 1 is characterized in that: The cement kiln system further comprises a tertiary air duct (10); one end of the tertiary air duct (10) is connected to the grate cooler (9), and the other end is connected to the smoke chamber (17).

7. The system of anaerobic pyrolysis and upgrading of domestic waste coupled with cement kiln according to claim 1 is characterized in that: An air cooler (21) is also provided between the rapid cooling air mixing chamber (20) and the second dust collector (22).

8. The system of anaerobic pyrolysis and upgrading of domestic waste coupled with cement kiln according to claim 1 is characterized in that: A first safety valve (18) is provided on the connecting pipeline between the smoke chamber (17) and the cooling fan (19); and a second safety valve (23) is provided on the connecting pipeline between the second dust collector (22) and the second induced draft fan (24).

9. The system of anaerobic pyrolysis and upgrading of domestic waste coupled with cement kiln according to claim 8, characterized in that: The second dust collector (22) is a bag dust collector; and the feeder (2) is a plate feeder.

10. A method for anaerobic pyrolysis and upgrading of domestic waste coupled with a cement kiln, characterized in that: A system for anaerobic pyrolysis and upgrading of domestic waste coupled with a cement kiln according to any one of claims 1 to 9 comprises the following steps: The domestic waste in the waste storage tank (1) is transported to a drying furnace (4) for pre-drying to remove moisture; then, the domestic waste is subjected to oxygen-free pyrolysis at a temperature of 400° C. to 500° C. in a pyrolysis furnace (6) to generate waste charcoal containing high chlorine, and the waste charcoal enters a rotary kiln (11) or is stored in a coal storage bin (8); The cement raw material passes through a suspension preheater (15), a decomposition furnace (16) and a smoke chamber (17), and then enters a rotary kiln (11), where it is burned with garbage charcoal at a temperature of 1300° C. to 1500° C. to obtain cement clinker; the cement clinker enters a grate cooler (9) for cooling; and at the same time, smoke generated in the rotary kiln (11) is collected in the smoke chamber (17); The flue gas in the smoke chamber (17) flows into the bypass exhaust system, is mixed with cold air in the quenching air mixing chamber 20 through the cooling fan (19), then passes through the second dust collector (22) to produce chlorine crystals from harmful components in the gas, and is finally discharged to the chimney (25) through the second induced draft fan (24).

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