Waste incineration and fly ash biogas oxygen-enriched melting system

Abstract

The utility model relates to the technical field of fly ash treatment, in particular to a waste incineration and fly ash biogas oxygen-enriched melting system which comprises a garbage pit, and a garbage incinerator, a waste heat boiler, a semi-dry reaction tower, a first bag-type dust collector, a melting furnace combustion-supporting air preheater and a first chimney which are sequentially connected are arranged on one side of the garbage pit. A slag outlet of the garbage incinerator is connected with an inlet of the melting furnace, a spray gun is arranged in the melting furnace, a leachate outlet of the garbage pit is connected with an inlet of the anaerobic reactor, and a biogas outlet of the anaerobic reactor, an outlet of the oxygen generator and a melting furnace combustion-supporting air outlet of the melting furnace combustion-supporting air preheater are all communicated with the spray gun; a smoke outlet of the melting furnace is connected with a smoke cooler, the smoke cooler is connected with a second bag-type dust collector, the second bag-type dust collector is connected with a deacidification tower, and an outlet of the deacidification tower is connected with a second chimney. According to the system, the biogas generated by the waste incineration power plant is used as fuel, so that the biogas is utilized, the fly ash melting cost is reduced, and the harmlessness of the fly ash is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of fly ash treatment, in particular to a waste incineration and fly ash biogas oxygen-enriched melting system. Background Art

[0002] Waste incineration has become the main means of domestic waste treatment due to its advantages of harmlessness, reduction, and resource utilization. Municipal solid waste incineration fly ash (hereinafter referred to as "fly ash") is the capture product of the flue gas purification system of municipal solid waste incineration facilities, and its generation amount is about 2.5% - 3.5% (for grate-fired incinerators) of the total amount of waste entering the furnace. By 2025, the domestic fly ash generation amount is expected to reach 24,000 tons per day (estimated based on an average production rate of 3% and a municipal solid waste incineration volume of 800,000 tons per day). Fly ash contains heavy metals such as arsenic, lead, chromium, zinc, copper, nickel, cadmium, manganese, and harmful substances such as dioxins / furans (PCDD / Fs), and is listed in the "National Hazardous Waste List (2021 Edition)", treated as hazardous waste, and cannot be directly landfilled in landfills. It is necessary to build supporting waste incineration fly ash treatment and disposal facilities for harmless treatment. If municipal solid waste incineration fly ash cannot be properly disposed of, it will become a new environmental pollution source, seriously hindering the healthy and sustainable development of the municipal solid waste incineration industry. With the wide application of waste incineration technology in the treatment of domestic waste in various cities, municipal solid waste incineration fly ash will become one of the important factors affecting the environment. First-tier cities represented by Beijing, Shanghai, Guangzhou, and Shenzhen and most second-tier cities are urgently in need of a thorough, safe, and economical fly ash treatment technology to achieve the harmlessness, reduction, and resource utilization of fly ash.

[0003] High-temperature melting technology can solidify heavy metals in fly ash into glass bodies and decompose dioxins in fly ash at the same time, which is a relatively thorough technology for fly ash harmlessness. Fly ash high-temperature melting generally uses electric furnaces, natural gas or coal oxygen-enriched melting furnaces, but these two methods have high costs and are not conducive to the application and promotion of fly ash melting technology. If an electric furnace is used, about 1200 degrees or more of electricity consumption is required for one ton of fly ash. Calculated at a electricity price of 0.5 yuan per degree, the melting energy consumption cost is 600 yuan per ton of fly ash. If natural gas is used, about 100 cubic meters or more of natural gas is required for one ton of fly ash. Calculated at a natural gas price of 4 yuan per cubic meter, the energy consumption cost is 400 yuan per ton of fly ash.

[0004] CN112594692A discloses a fuel self-sufficient fly ash melting waste incineration harmless system and treatment method, which extracts biogas from the bottom of the waste pit and sends it into the biogas storage tank, and further sends the biogas into the melting furnace for combustion. The combustion-supporting air absorbs part of the heat from the flue gas and then is sent into the melting furnace for combustion support. However, the biggest problem with this technology is that there is a biogas outlet at the bottom of its waste storage pit (i.e., the biogas comes from the waste pit), which is impossible to achieve in practice.

[0005] Therefore, there is an urgent need in the art to develop a more cost-effective oxygen-enriched melting system for fly ash to solve the problem of high cost in the current fly ash melting method. Summary of the Invention

[0006] The technical problem to be solved by the present utility model is to provide a waste incineration and fly ash biogas oxygen-enriched melting system, which uses the biogas generated by a waste incineration power plant as fuel, not only utilizes the biogas, but also reduces the cost of fly ash melting, and realizes the harmless treatment of fly ash.

[0007] To solve the above technical problem, the present application provides the following technical solutions:

[0008] A waste incineration and fly ash biogas oxygen-enriched melting system includes a waste pit, and on one side of the waste pit, there are successively connected a waste incinerator, a waste heat boiler, a semi-dry reaction tower, a first bag filter, a melting furnace combustion air preheater, and a first chimney;

[0009] The slag outlet of the waste incinerator is connected to the inlet of the melting furnace. There is a spray gun in the melting furnace. The leachate outlet of the waste pit is connected to the inlet of the anaerobic reactor. The biogas outlet of the anaerobic reactor, the outlet of the oxygen generator, and the melting furnace combustion air outlet of the melting furnace combustion air preheater are all connected to the spray gun;

[0010] The flue gas outlet of the melting furnace is connected to a flue gas cooler, the flue gas cooler is connected to a second bag filter, the second bag filter is connected to a deacidification tower, and the outlet of the deacidification tower is connected to a second chimney.

[0011] Further, the spray gun can move in the up and down directions.

[0012] Further, the spray gun includes an oxygen-enriched air inlet pipe, the oxygen-enriched air inlet pipe is connected to an annular oxygen-enriched air main pipe, the inner side of the oxygen-enriched air main pipe is connected to an oxygen-enriched air spray pipe through a plurality of evenly distributed oxygen-enriched air swirl spray pipes, and a biogas spray pipe is axially penetrated through the middle of the oxygen-enriched air spray pipe, and the lower end of the oxygen-enriched air spray pipe and the lower end of the biogas spray pipe are connected.

[0013] Further, the biogas outlet of the anaerobic reactor is connected to the biogas spray pipe.

[0014] Further, the outlet of the oxygen generator and the melting furnace combustion air outlet of the melting furnace combustion air preheater are connected to the oxygen-enriched air inlet pipe.

[0015] Further, the air outlet of the flue gas cooler is connected to the waste pit.

[0016] Compared with the prior art, the waste incineration and fly ash biogas oxygen-enriched melting system of the present utility model has at least the following beneficial effects:

[0017] (1) The utility model uses the biogas generated by anaerobic fermentation of the leachate anaerobic reactor in the waste incineration power plant as the fuel for the high-temperature melting vitrification treatment of fly ash, and uses the electricity generated by the waste power plant to provide electrical energy for the oxygen generator, realizing the recycling of energy.

[0018] (2) The biogas generated by the waste incineration power plant is used as the melting fuel, replacing the electricity or natural gas used as the fuel in the conventional melting scheme. The biogas generated by the waste incineration power plant is a by-product of the leachate anaerobic fermentation process, and the cost is basically zero. Therefore, the cost of using biogas for fly ash melting is basically zero. Therefore, this scheme has a lower cost than the conventional oxygen-enriched melting. Because biogas is a by-product of the waste power plant, if the biogas of the waste power plant is used, the melting energy consumption can be greatly reduced. At the same time, the energy consumption can be further reduced through this system, and the reliability and stability of the system can be improved.

[0019] (3) The biogas of this system is generated by the leachate generated in the garbage pit in the anaerobic reactor. The source of biogas is relatively stable, and biogas can be stably produced, solving the problem that biogas cannot be generated in the patent technologies such as CN112594692A.

[0020] (4) The spray gun adopted by this system uses a swirl nozzle to realize the downward rotation of the oxygen-enriched air, so that it can be very well mixed with the biogas, improving the combustion efficiency and strengthening the fly ash melting.

[0021] (5) This system utilizes the waste heat of the tail of the waste incineration flue gas purification system to heat the melting combustion-supporting air, further reducing the energy consumption required for melting.

[0022] (6) This system uses the bag filter of the melting furnace to collect the secondary fly ash, realizing the enrichment and recovery of chloride salts and heavy metals.

[0023] The following further describes the waste incineration and fly ash biogas oxygen-enriched melting system of the utility model with reference to the accompanying drawings. Description of the Drawings

[0024] Figure 1 It is a schematic diagram of the waste incineration and fly ash biogas oxygen-enriched melting system of the utility model;

[0025] Figure 2 It is a side view perspective schematic diagram of the spray gun;

[0026] Figure 3 It is a top view perspective schematic diagram of the spray gun.

[0027] Among them, 1 - garbage truck; 2 - garbage pit; 3 - garbage incinerator; 4 - waste heat boiler; 5 - flue gas; 6 - semi-dry reaction tower; 7 - first bag filter; 8 - fly ash; 9 - leachate; 10 - anaerobic reactor; 11 - biogas; 12 - oxygen generator; 13 - melting furnace; 14 - flue gas cooler; 15 - second bag filter; 16 - deacidification tower; 17 - first chimney; 18 - second chimney; 19 - slag; 20 - cold air; 21 - spray gun; 22 - combustion air preheater for melting furnace; 23 - combustion air for melting furnace.

[0028] 211 - oxygen-enriched air inlet pipe; 212 - oxygen-enriched air swirl nozzle; 213 - oxygen-enriched air main pipe; 214 - oxygen-enriched air nozzle; 215 - biogas nozzle. Specific implementation manner

[0029] As Figure 1 shown, a garbage incineration and fly ash biogas oxygen-enriched melting system includes a garbage pit 2. On one side of the garbage pit 2, there are successively connected a garbage incinerator 3, a waste heat boiler 4, a semi-dry reaction tower 6, a first bag filter 7, a combustion air preheater 22 for melting furnace and a first chimney 17. The slag outlet of the garbage incinerator 3 is connected to the inlet of the melting furnace 13. A spray gun 21 is provided in the melting furnace 13. The leachate outlet of the garbage pit 2 is connected to the inlet of the anaerobic reactor 10. The biogas outlet of the anaerobic reactor 10, the outlet of the oxygen generator 12 and the combustion air outlet of the combustion air preheater 22 for melting furnace are all connected to the spray gun 21. The flue gas outlet of the melting furnace 13 is connected to the flue gas cooler 14. The flue gas cooler 14 is connected to the second bag filter 15. The second bag filter 15 is connected to the deacidification tower 16. The outlet of the deacidification tower 16 is connected to the second chimney 18. The air outlet of the flue gas cooler 14 is connected to the garbage pit 2.

[0030] The spray gun 21 can move in the up and down direction. As Figures 2-3 shown, the spray gun 21 includes an oxygen-enriched air inlet pipe 211. The oxygen-enriched air inlet pipe 211 is connected to an annular oxygen-enriched air main pipe 213. The inner side of the oxygen-enriched air main pipe 213 is connected to an oxygen-enriched air nozzle 214 through a plurality of evenly distributed oxygen-enriched air swirl nozzles 212. The middle part of the oxygen-enriched air nozzle 214 is axially penetrated by a biogas nozzle 215. The lower end of the oxygen-enriched air nozzle 214 and the lower end of the biogas nozzle 215 are connected.

[0031] The biogas outlet of the anaerobic reactor 10 is connected to the biogas nozzle 215. The outlet of the oxygen generator 12 and the combustion air outlet of the combustion air preheater 22 for melting furnace are connected to the oxygen-enriched air inlet pipe 211.

[0032] The spray gun 21 adopts a double-layer sleeve structure. The inner spray pipe is for biogas, and the outer spray pipe is for oxygen-enriched air. The outer spray pipe is connected to the oxygen-enriched air main pipe through four or more oxygen-enriched air swirl spray pipes. The oxygen-enriched air enters the oxygen-enriched air main pipe through the inlet pipe, and then is sprayed into the oxygen-enriched air spray pipe of the spray gun by the swirl spray pipe, realizing the swirl of the oxygen-enriched air in the spray pipe, and strengthening the mixing with biogas at the outlet of the oxygen-enriched air spray pipe, improving the combustion effect and heat transfer effect, making the stirring and mixing of the flame on the molten bath more intense, and accelerating the melting of the fly ash material. The structure of this spray gun is significantly different from traditional spray guns. There are two types of traditional spray guns. One type has no swirl, and the other type uses blades to achieve swirl mixing. While the spray gun of this system uses an intake swirl spray pipe to achieve swirl, realizing an efficient mixing effect, and at the same time solving the problem of blade deformation and shedding at high temperatures caused by using blades for mixing.

[0033] Moreover, the whole spray gun can move up and down, improving the flexibility of operation, and effectively preventing the molten slag in the furnace from solidifying, which affects the stable operation of the system.

[0034] The working method of this waste incineration and fly ash biogas oxygen-enriched melting system is specifically as follows:

[0035] Municipal solid waste is transported by the garbage truck 1 to the garbage pit 2 of the waste incineration power plant. After fermenting in the garbage pit 2, it is grabbed by the garbage crane and sent into the waste incineration furnace 3. The garbage is incinerated in the waste incineration furnace 3 to generate high-temperature flue gas. The flue gas 5 after the heat is recovered by the waste heat boiler 4 passes through the semi-dry reaction tower 6 for acid removal, the first bag filter 7 for dust removal, and finally passes through the first chimney 17 to meet the emission standards. The fly ash 8 generated by the semi-dry reaction tower 6 and the first bag filter 7 and the slag 19 generated by the waste incineration furnace 3 are jointly sent into the melting furnace 13 for high-temperature vitrification treatment to solidify heavy metals and decompose dioxins.

[0036] The leachate 9 is generated after the garbage in the garbage pit 2 is piled up and fermented. The leachate undergoes anaerobic fermentation in the anaerobic reactor 10 to generate biogas 11. The biogas 11 is sent into the spray gun 21 as the fuel for high-temperature melting of fly ash to perform high-temperature melting on the fly ash. The oxygen generator 12 (or oxygen tank) provides oxygen-enriched air for biogas melting, thereby increasing the melting temperature and reducing fuel consumption. The combustion-supporting air 23 for the melting furnace is mixed with the oxygen-enriched air after passing through the combustion-supporting air preheater 22 for the melting furnace and then sent into the spray gun 21. The flue gas generated by the melting furnace 13 first undergoes denitrification through SNCR, and then enters the flue gas cooler 14 to recover heat. The cold air 20 is heated in the flue gas cooler 14 and then enters the garbage pit 2 to heat the garbage, which can promote garbage fermentation, reduce the moisture content of the garbage, and improve the garbage incineration effect. The flue gas of the melting furnace passing through the flue gas cooler 14 successively passes through the second bag filter 15 and the acid removal tower 16 and then is discharged through the second chimney 18. The recovered heat is used to heat the primary air of the boiler, thereby reducing the steam consumption for the primary air. The flue gas after heat recovery is treated by the flue gas purification system and then meets the emission standards.

[0037] As Figures 2-3 shown, the oxygen-enriched air enters the oxygen-enriched air main pipe 213 through the oxygen-enriched air inlet pipe 1, and is sprayed into the oxygen-enriched air nozzle via the oxygen-enriched air swirl nozzle 212. The oxygen-enriched air is fully mixed with the biogas at the lower part of the oxygen-enriched air nozzle 214. The biogas flows downward through the biogas nozzle 215 and is mixed with the oxygen-enriched air at the lower part of the lance. Due to the swirl action of the oxygen-enriched air swirl nozzle 212, the oxygen-enriched air and the biogas are strongly mixed at the lower part of the lance, which is beneficial to the combustion process.

[0038] The heat of the molten flue gas is recovered by the gas cooler of the melting furnace system to heat the garbage pit to promote the fermentation of garbage. After the garbage ferments, it is beneficial to the generation of leachate, which is discharged into the anaerobic reactor, promoting the generation of biogas, and increasing the calorific value of the garbage entering the incinerator, improving the incineration effect. Through this heat recovery system, the mutual promotion between the garbage incineration and the fly ash biogas oxygen-enriched melting system is realized.

[0039] After the fly ash comes out of the reaction tower and the bag filter, it directly enters the melting furnace through the conveying equipment. At this time, it still has a certain temperature, which can save the energy required for melting and further reduce the energy consumption. However, the current fly ash melting systems have not achieved the energy-saving effect through this system.

[0040] The bag filter is set to recover calcium chloride, potassium chloride, sodium chloride and heavy metals. In this system, the fly ash is directly fed into the furnace, and the temperature is controlled by the biogas oxygen-enriched combustion lance, so that calcium chloride, potassium chloride, sodium chloride and heavy metals can be volatilized and enriched for recovery, solving the problem of secondary pollution in the fly ash melting process. The existing fly ash melting systems have not achieved this function.

[0041] The combustion-supporting air of the melting furnace is preheated by using the waste heat at the tail of the garbage incineration flue gas purification system, further reducing the energy consumption of melting, while reducing the flue gas temperature discharged from the flue gas purification system and reducing the heat loss. However, the existing fly ash melting systems have not adopted this technology to achieve the effect of cost reduction.

[0042] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A waste incineration and fly ash biogas oxygen-enriched melting system, characterized in that: It includes a garbage pit (2), and on one side of the garbage pit (2), there are successively connected a garbage incinerator (3), a waste heat boiler (4), a semi-dry reaction tower (6), a first bag filter (7), a melting furnace combustion air preheater (22), and a first chimney (17); The slag outlet of the garbage incinerator (3) is connected to the inlet of the melting furnace (13). There is a spray gun (21) in the melting furnace (13). The leachate outlet of the garbage pit (2) is connected to the inlet of the anaerobic reactor (10). The biogas outlet of the anaerobic reactor (10), the outlet of the oxygen generator (12), and the melting furnace combustion air outlet of the melting furnace combustion air preheater (22) are all connected to the spray gun (21); The flue gas outlet of the melting furnace (13) is connected to the flue gas cooler (14). The flue gas cooler (14) is connected to the second bag filter (15). The second bag filter (15) is connected to the deacidification tower (16). The outlet of the deacidification tower (16) is connected to the second chimney (18).

2. The waste incineration and fly ash biogas oxygen-enriched melting system according to claim 1, characterized in that: The spray gun (21) can move in the up and down direction.

3. The waste incineration and fly ash biogas oxygen-enriched melting system according to claim 2, wherein: The spray gun (21) includes an oxygen-enriched air inlet pipe (211). The oxygen-enriched air inlet pipe (211) is connected to an annular oxygen-enriched air main pipe (213). The inner side of the oxygen-enriched air main pipe (213) is connected to an oxygen-enriched air spray pipe (214) through a plurality of evenly distributed oxygen-enriched air swirl spray pipes (212). The middle part of the oxygen-enriched air spray pipe (214) is axially penetrated by a biogas spray pipe (215). The lower end of the oxygen-enriched air spray pipe (214) and the lower end of the biogas spray pipe (215) are connected and communicated.

4. The waste incineration and fly ash biogas oxygen-enriched melting system according to claim 3, wherein: The biogas outlet of the anaerobic reactor (10) is connected to the biogas spray pipe (215).

5. The waste incineration and fly ash biogas oxygen-enriched melting system according to claim 4, characterized in that: The outlet of the oxygen generator (12) and the melting furnace combustion air outlet of the melting furnace combustion air preheater (22) are connected to the oxygen-enriched air inlet pipe (211).

6. The waste incineration and fly ash biogas oxygen-enriched melting system according to claim 1, wherein: The air outlet of the flue gas cooler (14) is connected to the garbage pit (2).

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