Low-cost waste fly ash melting treatment process

Abstract

The application discloses a low-cost garbage fly ash melting treatment process. Garbage first enters a garbage low-temperature anaerobic drying device, is dried by heating and is divided into two parts; the dried garbage enters a garbage high-temperature anaerobic pyrolysis gasification device, the gasification fuel gas and solid residue enter a high-temperature melting rotary incinerator, and are combusted and heat-released in the high-temperature melting rotary incinerator to form a temperature field above 1300 DEG C; the fly ash collected by a garbage power plant, the ash collected by an exhaust gas treatment system and the gasification residue sent by the garbage high-temperature anaerobic pyrolysis gasification device are sent into the high-temperature melting rotary incinerator together, are high-temperature calcined to a melting state, the generated molten slag successively passes through a flue gas heating cold slag cooler, a dry gas heating cold slag cooler and an air preheating cold slag cooler and finally forms a solidification state. The application solves the problem of high cost of treating garbage fly ash hazardous waste by a garbage power plant, and the pyrolysis fly ash of the process and the fly ash are treated in the process, and no hazardous waste is additionally generated.

Description

Technical Field

[0001] This invention relates to the field of waste treatment system technology, and specifically to a low-cost waste fly ash melting treatment process. Background Technology

[0002] Waste-to-energy incineration, as the best way to dispose of municipal solid waste in a "reduced, harmless, and resource-efficient" manner, has attracted great attention and concern from the state. Because the furnace temperature during waste incineration is higher than the gasification temperature of most heavy metals, the fly ash contains a high level of heavy metals and dioxins that are adsorbed by activated carbon. my country has explicitly classified incineration fly ash as hazardous waste, generating over 320 million tons of fly ash annually, requiring specialized treatment before landfilling.

[0003] Currently, the treatment methods for fly ash from waste incinerators include ambient temperature cement solidification landfill (which involves water-soluble salt leaching and incomplete dioxin removal), hydrothermal solidification landfill (which suffers from immature technology, high equipment requirements, high treatment costs, and incomplete dioxin removal), cement kiln co-processing (where dioxins are completely incinerated, and the slag after high-temperature sintering can be used as building material, but low chlorine content is required to avoid affecting cement quality, thus limiting the processing capacity), and high-temperature melting treatment (which can use external heating sources such as electricity or natural gas, and the treated fly ash can be used as raw material for high-grade microcrystalline boards and rock wool, but the treatment cost is high). High-temperature melting is the best method for reducing, rendering harmless, and recycling fly ash.

[0004] Currently, the mainstream methods for disposing of fly ash from waste incinerators, whether through solidification and landfill or high-temperature melting, all suffer from high disposal costs, which have become a significant part of the cost expenditures of waste-to-energy plants and have seriously affected the economic benefits of BOT waste incineration power plants. Summary of the Invention

[0005] The problem to be solved by this invention is to provide a low-cost waste fly ash melting process that can effectively reduce the operating costs of waste incineration power plants.

[0006] The technical solution provided by this invention to solve the above problems is: a low-cost waste fly ash melting treatment process, wherein the waste first enters a low-temperature oxygen-free drying device, and after heating and drying, it is divided into two parts, one part is the dried waste, and the other part is the drying gas generated during drying;

[0007] After drying, the waste enters a high-temperature anaerobic pyrolysis gasification device. The gasified fuel and solid residue enter a high-temperature melting rotary incinerator, where they burn and release heat, creating a temperature field of over 1300°C.

[0008] The fly ash collected from the waste-to-energy plant, the ash collected from the exhaust gas treatment system, and the gasification residue from the waste high-temperature anaerobic pyrolysis gasification device are fed together into a high-temperature molten rotary incinerator. The incinerator is calcined at high temperature until it reaches a molten state. The resulting molten slag is then cooled sequentially by a flue gas heating slag cooler, a dry gas heating slag cooler, and an air preheating slag cooler, finally solidifying and being utilized in a comprehensive manner.

[0009] Preferably, the drying gas generated by the low-temperature oxygen-free drying device for waste is powered by blower II, flows through the drying gas heating slag cooler and enters the high-temperature melting rotary incinerator, where it is burned at high temperature to form harmless gas that is incorporated into the flue gas process.

[0010] Preferably, in the process of waste drying and high-temperature pyrolysis, a portion of the high-temperature flue gas from the incinerator is used as the heat source medium for waste pyrolysis and drying, and the flue gas does not come into direct contact with the waste.

[0011] Preferably, the drying gas from the low-temperature oxygen-free drying device is powered by blower II, flows through the drying gas heating slag cooler, and enters the high-temperature melting rotary incinerator.

[0012] Preferably, the cold air is powered by blower I, heated by the air preheater and slag cooler, and then enters the high-temperature melting rotary incinerator. It is mixed with the fuel gas and fixed carbon in the residue sent into the high-temperature melting rotary incinerator by the waste high-temperature anaerobic pyrolysis gasification device, and then fully combusted in the high-temperature melting rotary incinerator.

[0013] Preferably, the high-temperature flue gas generated in the high-temperature melting rotary incinerator is divided into two parts by a flue gas regulating valve. One part flows sequentially through the high-temperature anaerobic pyrolysis gasification device, the low-temperature anaerobic drying device, and the flue gas heating slag cooler. After the flue gas regulating valve, it merges with the remaining high-temperature flue gas from the high-temperature melting rotary incinerator and enters the waste heat boiler system. Then, it is sent into the chimney by an induced draft fan through the tail gas treatment system.

[0014] Compared with existing technologies, the advantages of this invention are: This invention utilizes waste from the waste-to-energy plant as fuel, and after two upgrading processes—drying and gasification—the fuel is burned in a high-temperature rotary kiln to generate a temperature field exceeding 1300°C. This process melts and treats both the hazardous fly ash from the waste-to-energy plant and the fly ash generated by the system itself, and renders the harmful gases, such as the drying gas produced by the system, harmless. Since this process system operates entirely on waste collected from the power plant as fuel, its operating costs are very low, effectively reducing the power plant's operating costs compared to currently used hazardous fly ash treatment processes. Attached Figure Description

[0015] The accompanying drawings, which are provided to further illustrate the invention and constitute a part of this invention, are illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention.

[0016] Figure 1 This is a process system diagram of the present invention.

[0017] Attached figures are labeled as follows: 1. Low-temperature oxygen-free drying device for waste; 2. High-temperature oxygen-free pyrolysis and gasification device for waste; 3. High-temperature melting rotary incinerator; 4. Blower I; 5. Flue gas heating slag cooler; 6. Drying gas heating slag cooler; 7. Air preheating slag cooler; 8. Blower II; 9. Flue gas regulating valve; 10. Waste heat boiler system; 11. Tail gas treatment system; 12. Exhaust fan. Detailed Implementation

[0018] The following will describe in detail the implementation of the present invention with reference to the accompanying drawings and embodiments, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0019] In the description of this invention, it should be noted that the directional terms such as "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this invention.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Thus, the use of "first" and "second" to define a feature may explicitly or implicitly include one or more of that feature, and in the description of this invention, "a number" means two or more, unless otherwise explicitly specified.

[0021] In this invention, unless otherwise explicitly specified and limited, the terms "assembly," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection; they can refer to a direct connection or a connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0023] It should also be understood that the terminology used in this specification of embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the invention. As used in this specification of embodiments of the invention and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0024] As shown in the attached drawings, a low-cost waste fly ash melting treatment process is provided. The waste first enters a low-temperature oxygen-free drying device 1, and after heating and drying, it is divided into two parts: one part is the dried waste, and the other part is the drying gas generated during drying.

[0025] After drying, the waste enters the high-temperature anaerobic pyrolysis gasification device 2. The gasified fuel and solid residue enter the high-temperature melting rotary incinerator 3, where they burn and release heat, forming a temperature field of over 1300°C.

[0026] The fly ash collected from the waste-to-energy plant and fed into this process system, the ash collected by the tail gas treatment system 11 in this process system, and the gasification residue fed into the waste high-temperature anaerobic pyrolysis gasification device 2 are all fed into the high-temperature melting rotary incinerator 3. They are calcined at high temperature to a molten state. The resulting molten slag is successively cooled by the flue gas heating slag cooler 5, the dry gas heating slag cooler 6, and the air preheating slag cooler 7, and finally forms a solidified state for comprehensive utilization.

[0027] It should be noted that, since the waste collected by waste-to-energy plants has high moisture and ash content and low calorific value, the temperature field generated by directly burning the waste is insufficient to achieve the purpose of melting the fly ash. Therefore, the process of this invention adopts a two-stage upgrading treatment of the waste, namely low-temperature oxygen-free drying and high-temperature oxygen-free pyrolysis gasification, in order to improve the adiabatic combustion temperature and stably achieve the target of high temperature (>1300℃) required for melting.

[0028] The low-temperature oxygen-free drying unit and the high-temperature oxygen-free pyrolysis gasification unit for waste use high-temperature flue gas generated in the high-temperature melting rotary incinerator of this process system as their heat source. Because the waste in the low-temperature oxygen-free drying unit and the high-temperature oxygen-free pyrolysis gasification unit is in an oxygen-free state, the generation of dioxins is avoided.

[0029] As a further improvement of this embodiment, the drying gas generated by the low-temperature oxygen-free drying device for waste is powered by blower II8, flows through the drying gas heating slag cooler 6 and enters the high-temperature melting rotary incinerator 3, where it is burned at high temperature to form harmless gas and is incorporated into the flue gas process.

[0030] As a further improvement to this embodiment, in the waste drying and high-temperature pyrolysis, a portion of the high-temperature flue gas from the incinerator is used as the heat source medium for waste pyrolysis and drying, and the flue gas does not come into direct contact with the waste.

[0031] As a further improvement of this embodiment, the drying gas from the low-temperature oxygen-free drying device 1 is powered by the blower II 8, flows through the drying gas heating slag cooler 6, and enters the high-temperature melting rotary incinerator 3.

[0032] As a further improvement of this embodiment, the cold air is powered by blower I4, heated by air preheater slag cooler 7, and then enters high-temperature melting rotary incinerator 3. After mixing with the fuel gas and fixed carbon in the residue sent into high-temperature melting rotary incinerator 3 by waste high-temperature anaerobic pyrolysis gasification device 2, it is fully combusted in high-temperature melting rotary incinerator 3.

[0033] As a further improvement of this embodiment, the high-temperature flue gas generated by combustion in the high-temperature melting rotary incinerator 3 is divided into two parts by the flue gas regulating valve. One part flows sequentially through the high-temperature oxygen-free pyrolysis gasification device 2, the low-temperature oxygen-free drying device 1, and the flue gas heating slag cooler 5. After the flue gas regulating valve, it merges with the remaining high-temperature flue gas of the high-temperature melting rotary incinerator 3 and enters the waste heat boiler system 10. Then, it is sent into the chimney by the induced draft fan 12 through the tail gas treatment system 11.

[0034] The heat sources in both the low-temperature oxygen-free drying device 1 and the high-temperature oxygen-free pyrolysis gasification device 2 are drawn from the flue gas generated in the high-temperature melting rotary incinerator 3. This flue gas does not directly contact the waste for heating. A portion of the high-temperature flue gas generated in the high-temperature melting rotary incinerator 3 is first sent to the high-temperature oxygen-free pyrolysis gasification device 2 through the flue gas regulating valve 9 to gasify the waste. The cooled flue gas then enters the low-temperature oxygen-free drying device 1 to dry the waste. This portion of flue gas then enters the flue gas heating slag cooler 5 to heat the flue gas. After passing through the flue gas regulating valve 9, it merges with the remaining high-temperature flue gas from the high-temperature melting rotary incinerator 3 and enters the waste heat boiler system 10 for heat recovery and utilization.

[0035] The working process of this invention consists of three steps: a waste treatment process, a fly ash treatment process for waste-to-energy plants and the fly ash treatment process of the present invention's process system, and a flue gas process.

[0036] First, let's look at the waste treatment process. Waste is the heat provider in the process system of this invention. The raw waste first enters the low-temperature oxygen-free drying device 1, where it is heated and dried, then separated into two parts: the dried waste and the drying gas generated during drying. The dried waste then enters the high-temperature oxygen-free pyrolysis gasification device 2. The gasified fuel gas and solid residue enter the high-temperature melting rotary incinerator 3, where they burn and release heat, creating a temperature field above 1300°C. The drying gas is powered by blower II 8, flows through the drying gas heating slag cooler 6, and enters the high-temperature melting rotary incinerator 3, where it is burned at high temperature to form harmless gas that is then incorporated into the flue gas flow.

[0037] Secondly, the fly ash from the waste-to-energy plant and the fly ash treatment process of the present invention's process system are described. Fly ash is the object to be treated by the process system of the present invention. The fly ash collected from the waste-to-energy plant and fed into this process system, the ash collected by the exhaust gas treatment system 11, and the gasification residue fed into the waste high-temperature anaerobic pyrolysis gasification device 2 are all fed into the high-temperature melting rotary incinerator 3, where they are calcined at high temperature to a molten state. The resulting molten slag is then cooled sequentially through a flue gas heating slag cooler 5, a dry gas heating slag cooler 6, and an air preheating slag cooler 7, finally forming a solidified state for comprehensive utilization.

[0038] The third is the flue gas flow process. There are three flue gas flow paths. The first path is the dried gas from the low-temperature oxygen-free drying device 1, powered by blower II 8, flowing through the dried gas heating slag cooler 6 and entering the high-temperature melting rotary incinerator 3. The second path is the cold air powered by blower I 4, heated by the air preheating slag cooler 7, and then entering the high-temperature melting rotary incinerator 3. This air mixes with the fuel gas and fixed carbon in the residue sent to the high-temperature melting rotary incinerator 3 by the high-temperature oxygen-free pyrolysis gasification device 2, and then undergoes complete combustion in the high-temperature melting rotary incinerator 3. The third path is the high-temperature flue gas generated by combustion, which is divided into two parts by the flue gas regulating valve 9. One part flows sequentially through the high-temperature oxygen-free pyrolysis gasification device 2, the low-temperature oxygen-free drying device 1, and the flue gas heating slag cooler 5. After the flue gas regulating valve 9, it merges with the remaining high-temperature flue gas in the high-temperature melting rotary incinerator 3 and enters the waste heat boiler system 10. Then, it passes through the tail gas treatment system 11 and is sent into the chimney by the induced draft fan 12.

[0039] The above description only illustrates the preferred embodiments of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and variations in its specific structure are permitted. All modifications made within the scope of the independent claims of this invention are also within the scope of protection of this invention.

Claims

1. A low-cost waste fly ash melting treatment process, characterized in that: the waste first enters a waste low-temperature anaerobic drying device, and after drying by heating, is divided into two parts, one part being dried waste, and the other part being drying gas generated during drying; the dried waste enters a waste high-temperature anaerobic pyrolysis gasification device, and after gasification, the combustion gas and solid residue enter a high-temperature melting rotary incinerator and burn and release heat therein to form a temperature field of above 1300℃; the fly ash collected by the waste power plant, the ash collected by the tail gas treatment system, and the gasification residue sent by the waste high-temperature anaerobic pyrolysis gasification device are sent together into the high-temperature melting rotary incinerator, and are high-temperature calcined to a molten state, the molten slag generated is cooled in sequence by a flue gas heating cold slag cooler, a drying gas heating cold slag cooler, and an air preheating cold slag cooler, and finally forms a solidified state for comprehensive utilization; the drying gas generated by the waste low-temperature anaerobic drying device is powered by a blower II, flows through the drying gas heating cold slag cooler, enters the high-temperature melting rotary incinerator, is high-temperature combusted to form a harmless gas, and enters the flue gas process; cold air is powered by a blower I, is heated by the air preheating cold slag cooler, and then enters the high-temperature melting rotary incinerator, mixes with fixed carbon in the combustion gas and residue sent by the waste high-temperature anaerobic pyrolysis gasification device into the high-temperature melting rotary incinerator, and is fully combusted in the high-temperature melting rotary incinerator; the high-temperature flue gas generated by combustion in the high-temperature melting rotary incinerator is divided into two parts by a flue gas regulating valve, one part flows in sequence through the waste high-temperature anaerobic pyrolysis gasification device, the waste low-temperature anaerobic drying device, and the flue gas heating cold slag cooler, and after the flue gas regulating valve, is combined with the remaining high-temperature flue gas of the high-temperature melting rotary incinerator, enters a waste heat boiler system, and then is sent by an induced draft fan into a chimney through a tail gas treatment system. The waste drying and high-temperature pyrolysis use a part of the high-temperature flue gas of the incinerator as a heat source medium for waste pyrolysis and drying, and the flue gas and the waste do not directly contact. ​ ​ ​ ​ ​ 2. A low cost waste incinerator fly ash melting process according to claim 1, characterized in that: ​

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