Anaerobic thermal cracking harmless treatment method for household garbage
By using an oxygen-free pyrolysis unit to treat municipal solid waste, the problem of toxic gases produced by incineration has been solved, achieving harmless treatment and resource utilization, and reducing energy consumption and costs.
Patent Information
- Application Number
- CN202411068337.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-06
- Publication Date
- 2026-01-23
AI Technical Summary
Existing methods for treating municipal solid waste, such as incineration, produce toxic and harmful gases and have high equipment costs, making them unsuitable for large-scale application.
The system employs an oxygen-free pyrolysis device, including a pyrolysis furnace, a screw feeder, an electromagnetic heating device, a condenser tower, and a vacuum pump. It heats municipal solid waste under oxygen-free conditions, causing it to pyrolyze at 300–600°C to produce biochar, pyrolysis liquid, and combustible gas, thus avoiding the generation of toxic substances.
It achieves harmless treatment, zero emissions, and low energy consumption. The generated biochar and pyrolysis liquid are usable, with excellent environmental performance. It is suitable for various types of waste, and has low cost and low energy consumption.
Smart Images
Figure CN121379629A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of municipal solid waste treatment technology, specifically to a method for the harmless treatment of municipal solid waste through anaerobic pyrolysis. Background Technology
[0002] With the continuous development of urbanization, the problem of household waste is becoming increasingly prominent, and waste disposal has become a key and challenging aspect of environmental protection. This waste mainly includes various types such as kitchen waste, other waste, household waste, and industrial waste. Statistics show that my country generates approximately 196.738 million tons of waste annually. If this waste is not disposed of in a timely manner, the accumulated household waste will pose a significant threat to the ecological environment and human health. Currently, the main method of waste disposal is incineration. While incineration is simple and fast, the toxic and harmful gases produced during incineration, such as dioxins, can seriously endanger human life. Furthermore, the tar left after incineration severely damages the soil environment. Moreover, existing household waste treatment equipment is costly and unsuitable for large-scale application. Summary of the Invention
[0003] The purpose of this invention is to provide a method for the harmless treatment of municipal solid waste through anaerobic pyrolysis, in order to solve the problems mentioned in the background art.
[0004] To achieve the above objectives, the technical solution of the present invention is as follows:
[0005] A method for harmless treatment of municipal solid waste by anaerobic pyrolysis, wherein the anaerobic pyrolysis device includes: a pyrolysis furnace 1, a screw feeder 2, an electromagnetic heating device 3, a condensation tower 4, a vacuum pump 5, a circulating water pump 6, and a liquid collection tank 7.
[0006] The pyrolysis furnace 1 consists of a molten salt furnace and a vacuum chamber. The molten salt furnace is placed inside the vacuum chamber. The bottom of the molten salt furnace is connected to an electromagnetic heating device 3. After the power is turned on, the molten salt furnace is heated by current or by the electromagnetic heating device 3, so that the temperature inside the pyrolysis furnace continuously increases.
[0007] The screw feeder 2 is connected to the outlet of the molten salt furnace and enters the molten salt furnace to feed domestic waste into the molten salt furnace;
[0008] The vacuum chamber is connected to the condenser 4 at the top, and the circulating water in the condenser 4 is driven by the circulating water pump 6; the condenser 4 condenses the pyrolysis gas generated during the pyrolysis process to produce pyrolysis liquid.
[0009] A vacuum pump 5 is also connected below the condenser tower 4 to create a negative pressure inside the vacuum box and condenser tower 4 to isolate oxygen.
[0010] The specific steps of this method are as follows:
[0011] Step 1) Open the feed inlet of the pyrolysis furnace 1 and pour the domestic waste into the screw feeder 2;
[0012] Step 2) Open the screw feeder 2 to allow all the domestic waste to enter the furnace;
[0013] Step 3) Turn on the electromagnetic heating device 3, set the temperature, or heat the molten salt furnace with electric current to raise the temperature of the thermal cracking furnace 1 to 300-600°C and maintain it for 30-150 minutes;
[0014] Step 4) Turn on the vacuum pump 5 and the circulating water pump 6 to keep the pyrolysis furnace under vacuum at all times and to continuously condense the generated gas.
[0015] Step 5) After the pyrolysis is completed, open the slag outlet of the pyrolysis furnace 1 and the liquid collection tank 7 to collect the biochar and pyrolysis liquid respectively.
[0016] Preferably, the oxygen-free thermal cracking device further includes a liquid collection tank 7, which is located below the condenser tower 4. The liquid condensed by the condenser tower 4 enters the liquid collection tank 7, and the liquid in the liquid collection tank 7 can be used at any time.
[0017] Preferably, the liquid taken from the liquid collection tank 7 is filtered to obtain the pyrolysis stock solution, and then refined pyrolysis solution is obtained through a series of operations such as distillation.
[0018] Preferably, the outlet end of the vacuum pump 5 is connected to a gas ignition device 8, which removes the uncondensed combustible gas from the condenser tower 4 by ignition.
[0019] Preferably, the gas ignition device 8 is used to heat the pyrolysis furnace 1.
[0020] Preferably, the household waste includes: kitchen waste, other waste, household waste and industrial waste, with a moisture content of 10-90 wt%.
[0021] Preferably, the molten salt furnace includes a unit molten salt furnace, a binary molten salt furnace, and a ternary molten salt furnace that use molten sodium nitrate, molten potassium nitrate, and molten potassium chloride as molten salt.
[0022] Preferably, the combustible gas after combustion is adsorbed and filtered using activated carbon or molecular sieves.
[0023] Preferably, the electromagnetic heating device 3 is connected to a voltage of 10-330V and a current of 0.5-2A.
[0024] Preferably, the filtration speed of the vacuum pump 5 is 15-30 L / s.
[0025] Preferably, the circulating water in the condenser tower 4 is connected to a heat exchange device for heating.
[0026] The beneficial effects of this invention are:
[0027] Compared with traditional incineration or oxygen-deficient pyrolysis gasification pyrolysis technologies, this invention can produce no toxic or harmful substances during the pyrolysis process, and has excellent environmental performance. It has great application prospects in the fields of municipal solid waste, agricultural and forestry waste, waste plastics, waste tires, medical waste, and industrial solid pollutants.
[0028] Anaerobic pyrolysis offers significant advantages in treating the above-mentioned areas, and its technology is highly innovative, simpler, safer, and can completely convert municipal solid waste into usable resources with zero emissions and low energy consumption, requiring only 0.008-0.03 kWh of electricity per kilogram. After pyrolysis, municipal solid waste produces biomass carbon with a specific surface area of 50.65-135.98 m². 2 / g, producing a harmless pyrolysis liquid with a pH of 2.9-3.42 and combustible gases such as propane, without producing dioxins, and can achieve full utilization. Attached Figure Description
[0029] Figure 1 A schematic diagram of the structure of an oxygen-free pyrolysis device for municipal solid waste provided by the present invention;
[0030] Figure 2 This is a process flow diagram for the pyrolysis treatment of municipal solid waste; Detailed Implementation
[0031] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.
[0032] Example 1
[0033] 25 kg of municipal solid waste with a moisture content of 10 wt% was poured into the pyrolysis furnace. The feeding program and electromagnetic heating device were turned on to start heating the molten salt furnace. The vacuum pump was turned on to maintain a vacuum in the pyrolysis furnace and to extract the generated gas outside the furnace. The circulating water pump was turned on to condense the gas in the condenser tower and send it into the liquid collection tank. When the temperature inside the pyrolysis furnace reached 300°C, the gas combustion device was turned on to burn the uncondensed combustible gas, and the temperature inside the pyrolysis furnace was controlled at 300°C. The municipal solid waste was kept in the pyrolysis furnace for 30 minutes. After the time was up, the temperature was allowed to drop to 180°C. The slag outlet and liquid collection tank were opened to collect the pyrolysis slag and wood vinegar. The yield of pyrolysis slag was 22.5%, and the yield of wood vinegar was 58.9%.
[0034] The specific surface area of the biochar is shown in Table 1, and the pH of the pyrolysis solution is shown in Table 2.
[0035] Table 1. Specific surface area of pyrolysis residues from various municipal solid wastes after anaerobic pyrolysis at different temperatures.
[0036]
[0037] Table 2 pH values of pyrolysis solutions at different temperatures
[0038]
[0039] Example 2
[0040] The difference between this embodiment and Embodiment 1 is that the municipal solid waste with a moisture content of 40 wt% was used, the temperature inside the pyrolysis furnace was controlled at 450°C and held for 100 minutes, the biochar yield was 18.9%, and the wood vinegar yield was 62.8%.
[0041] The combustible components and contents produced by pyrolysis of municipal solid waste are shown in Table 3, and the components and contents of the pyrolysis liquid are shown in Table 4.
[0042] Table 3. Combustible components and content of municipal solid waste produced by pyrolysis at 450℃
[0043]
[0044]
[0045] Table 4. Composition and content of pyrolysis liquid generated from municipal solid waste at 450℃
[0046]
[0047] Example 3
[0048] The difference between this embodiment and Embodiment 1 is that the municipal solid waste with a moisture content of 90 wt% was used, the temperature inside the pyrolysis furnace was controlled at 600°C and maintained for 150 minutes, the biochar yield was 13.8%, and the wood vinegar yield was 69.5%.
[0049] Example 4
[0050] The difference between this embodiment and Embodiment 1 is that other waste with a water content of 10wt% was used, the temperature inside the pyrolysis furnace was controlled at 300℃ and held for 60 minutes, the biochar yield was 23.2%, and the wood vinegar yield was 57.5%.
[0051] Example 5
[0052] The difference between this embodiment and Embodiment 1 is that other waste with a water content of 40wt% was used, the temperature inside the pyrolysis furnace was controlled at 450℃ and maintained for 100 minutes, the biochar yield was 19.7%, and the wood vinegar yield was 62.8%.
[0053] Example 6
[0054] The difference between this embodiment and Embodiment 1 is that other waste with a water content of 90wt% was used, the temperature in the pyrolysis furnace was controlled at 600℃ and held for 150 minutes, the biochar yield was 14.5%, and the wood vinegar yield was 67.3%.
[0055] Example 7
[0056] The difference between this embodiment and Embodiment 1 is that the food waste with a moisture content of 10wt% was used, the temperature inside the pyrolysis furnace was controlled at 300℃ and maintained for 60 minutes, the biochar yield was 23.5%, and the wood vinegar yield was 58.2%.
[0057] Example 8
[0058] The difference between this embodiment and Embodiment 1 is that the food waste with a moisture content of 40wt% was used, the temperature in the pyrolysis furnace was controlled at 450℃ and held for 100 minutes, the biochar yield was 19.1% and the wood vinegar yield was 63.4%.
[0059] Example 9
[0060] The difference between this embodiment and Embodiment 1 is that the food waste with a moisture content of 90wt% was used, the temperature inside the pyrolysis furnace was controlled at 600℃ and held for 150 minutes, the biochar yield was 14.5%, and the wood vinegar yield was 68.2%.
[0061] Example 10
[0062] The difference between this embodiment and Embodiment 1 is that the industrial waste with a water content of 10wt% was used, the temperature inside the pyrolysis furnace was controlled at 300℃ and held for 60 minutes, the yield of biochar was 22.7%, and the yield of wood vinegar was 58.8%.
[0063] Example 11
[0064] The difference between this embodiment and Embodiment 1 is that the industrial waste with a water content of 40wt% was used, the temperature inside the pyrolysis furnace was controlled at 450℃ and held for 100 minutes, the yield of biochar was 17.2%, and the yield of wood vinegar was 64.5%.
[0065] Example 12
[0066] The difference between this embodiment and Embodiment 1 is that the industrial waste with a water content of 90wt% was used, the temperature in the pyrolysis furnace was controlled at 600℃ and held for 150 minutes, the biochar yield was 12.8%, and the wood vinegar yield was 69.2%.
Claims
1. A method for the harmless treatment of municipal solid waste through anaerobic pyrolysis, characterized in that, The oxygen-free thermal cracking device includes: a thermal cracking furnace (1), a screw feeder (2), an electromagnetic heating device (3), a condenser tower (4), a vacuum pump (5), a circulating water pump (6), and a liquid collection tank (7); The pyrolysis furnace (1) consists of a molten salt furnace and a vacuum box. The molten salt furnace is set inside the vacuum box. The bottom of the molten salt furnace is connected to an electromagnetic heating device (3). After the power is turned on, the molten salt furnace is heated by current or by the electromagnetic heating device (3), so that the temperature inside the pyrolysis furnace continuously increases. The screw feeder (2) is connected to the outlet of the molten salt furnace and enters the molten salt furnace to feed domestic waste into the molten salt furnace; The vacuum chamber is connected to the condenser (4) at the top, and the circulating water in the condenser (4) is driven by the circulating water pump (6); the condenser (4) condenses the pyrolysis gas generated during the pyrolysis process to produce pyrolysis liquid; A vacuum pump (5) is also connected below the condenser (4) to create a negative pressure inside the vacuum box and condenser (4) to isolate oxygen. The specific steps of this method are as follows: Step 1) Open the feed port of the pyrolysis furnace (1) and pour the domestic waste into the screw feeder (2); Step 2) Open the screw feeder (2) so that all the domestic waste can enter the furnace; Step 3) Turn on the electromagnetic heating device (3), set the temperature, or heat the molten salt furnace by electric current to raise the temperature of the thermal cracking furnace (1) to 300-600℃ and maintain it for 30-150 minutes; Step 4) Turn on the vacuum pump (5) and the circulating water pump (6) to keep the pyrolysis furnace under vacuum at all times and to continuously condense the generated gas. Step 5) After the pyrolysis is completed, open the slag outlet and liquid collection box (7) of the pyrolysis furnace (1) to collect the artificial peat soil and pyrolysis liquid respectively.
2. The method for harmless treatment of municipal solid waste by anaerobic pyrolysis according to claim 1, characterized in that, The oxygen-free thermal cracking device also includes a liquid collection tank (7), which is located below the condenser tower (4). The liquid condensed by the condenser tower (4) enters the liquid collection tank (7), and the liquid in the liquid collection tank (7) can be used at any time.
3. The method for harmless treatment of municipal solid waste by anaerobic pyrolysis according to claim 1, characterized in that, The outlet end of the vacuum pump (5) is connected to a gas ignition device (8), which removes the uncondensed combustible gas from the condenser tower (4) by ignition.
4. The method for harmless treatment of municipal solid waste by anaerobic pyrolysis according to claim 3, characterized in that, The gas ignition device (8) is used to heat the pyrolysis furnace (1).
5. The method for harmless treatment of municipal solid waste by anaerobic pyrolysis according to claim 1, characterized in that, The term "domestic waste" includes: kitchen waste, other waste, household waste, and industrial waste, with a moisture content of 10–90 wt%.
6. The method for harmless treatment of municipal solid waste by anaerobic pyrolysis according to claim 1, characterized in that, The molten salt furnaces include unit molten salt furnaces, binary molten salt furnaces, and ternary molten salt furnaces that use molten sodium nitrate, molten potassium nitrate, and molten potassium chloride as molten salts.
7. The method for harmless treatment of municipal solid waste by anaerobic pyrolysis according to claim 1, characterized in that, The combustible gas after combustion is adsorbed and filtered using activated carbon or molecular sieves.
8. The method for harmless treatment of municipal solid waste by anaerobic pyrolysis according to claim 1, characterized in that, The electromagnetic heating device (3) is connected to a voltage of 10-330V and a current of 0.5-2A.
9. The method for harmless treatment of municipal solid waste by anaerobic pyrolysis according to claim 1, characterized in that, The vacuum pump (5) has a filtration speed of 15-30 L / s.
10. The method for harmless treatment of municipal solid waste by anaerobic pyrolysis according to claim 1, characterized in that, The circulating water in the condenser tower (4) is connected to the heat exchange device for heating.