Method and device for comprehensive treatment of restaurant kitchen waste

Abstract

The invention discloses a method and device for comprehensive treatment of restaurant kitchen waste. The restaurant kitchen waste is subjected to high-pressure dehydration and oil-water separation treatment, and the obtained oil is recycled as a chemical raw material. The wastewater is purified by biochar adsorption and used as water for greening; the biochar after adsorption and purification of wastewater is mixed with solid phase dehydrated residue for low-temperature pyrolysis treatment, and cooled to obtain high-salt biochar; the soluble salt in the high-salt biochar is dissolved by a water-soluble process to obtain desalted biochar and a salt-containing solution; the salt in the salt-containing solution is recovered as a chemical raw material by evaporation and crystallization, and the aqueous solution obtained after steam condensation is recycled; the desalted biochar is dried, and 50% to 70% of the obtained product is used as an adsorption material or soil improvement material, and 30% to 50% is recycled and reused as a wastewater adsorption and purification material. This method not only solves the environmental pollution problem of restaurant kitchen waste, but also realizes 100% resource recycling and energy self-supply, and has good economic and environmental benefits.

Description

Technical Field

[0001] The invention relates to the field of garbage disposal, and in particular to a method and device for comprehensive disposal of kitchen garbage. Background Art

[0002] The annual output of food waste in my country is about 40-50 million tons, and it grows at a rate of about 10% every year. The basic physical and chemical characteristics of food waste are high moisture (about 80-85%), high salt content and high organic matter content. It is very easy to rot and deteriorate, and breeds bacteria. It also contains nitrogen, phosphorus, potassium, calcium and various trace elements. Traditional methods of food waste disposal include sanitary landfill, discharge into sewers, as animal feed, mixed with garbage incineration or organic composting. CN107971326A A food waste conversion equipment and a food waste conversion system, which convert food waste into insect protein. CN205599656U discloses a skid-mounted food waste treatment system and a food waste treatment vehicle, which solve the secondary pollution problem caused by the traditional food waste treatment mode during collection, transportation, unloading and storage. The treated food waste can be used for power generation or hydrogen production and preparation of biodiesel. CN201811564165.6 A method for treating food waste solves the problem of separating aflatoxin from food waste, and the remaining solid food waste that does not contain aflatoxin can be used as organic fertilizer or feed after drying and other treatments.

[0003] CN202010211873.2 A method for treating kitchen waste, first removing part of the liquid waste in the kitchen waste, obtaining pre-treated kitchen waste, and then adding it to a hydrothermal reactor after crushing to obtain a hydrothermal carbonization product as an organic carbon fertilizer. CN112139222A first mixes the kitchen waste swill obtained after filtering and the kitchen waste slurry obtained after extrusion dehydration, and then performs oil extraction and dehydration treatment on the kitchen waste liquid after oil extraction and dehydration to produce biogas. CN109945199A discloses a kitchen waste incineration device for waste treatment, which is provided with a drying chamber for reducing the moisture content in the kitchen waste to less than 30% and an incineration chamber for completely incinerating the kitchen waste, effectively improving the incineration efficiency of the kitchen waste. CN201610114928.1 A restaurant waste composting system is used to perform fermentation and composting treatment on restaurant waste materials, thereby solving the problem of secondary pollution caused by insufficient incineration during the incineration and disposal of restaurant waste in the prior art.

[0004] Comprehensive analysis of the current research status at home and abroad shows that the current treatment of food waste mainly focuses on direct mixed composting or mixed fermentation to produce biogas, which has the disadvantages of low scale treatment efficiency, insufficient resource utilization, low gas production efficiency, easy to produce secondary pollution, high disposal cost, and failure to classify and recycle by-products. Therefore, it is urgent to develop new comprehensive food waste treatment technologies to achieve efficient reduction and high value-added resource utilization. Summary of the invention

[0005] The problem to be solved by the present invention is to overcome the shortcomings of the prior art. In view of the insufficient resource utilization of the existing kitchen waste mentioned above, the kitchen waste is directly dehydrated and then pyrolyzed and comprehensively treated to obtain four types of products: oil, green water, salt and biochar, so as to achieve efficient resource utilization of kitchen waste, obtain various by-products in a low-carbon, efficient and clean manner, and achieve the goals of making the best use of resources, saving energy and protecting the environment, and reducing costs.

[0006] To achieve the above object, the present invention provides a method for comprehensive treatment of kitchen waste, characterized in that it comprises the following steps:

[0007] S1: Dehydrating the kitchen waste under high pressure to obtain solid dehydrated residue and dehydrated liquid;

[0008] S2: The dehydrated liquid is subjected to oil-water separation treatment to obtain oil and wastewater, wherein the oil is recycled as a chemical raw material, and the wastewater is used for greening water after being purified by biochar adsorption;

[0009] S3: The biochar after adsorption and purification of wastewater is mixed with the solid dehydrated slag obtained in S1 and subjected to low-temperature pyrolysis treatment, and high-salt biochar is obtained after cooling;

[0010] S4: using a water-soluble process to dissolve the soluble salt in the obtained high-salt biochar, and then separating the solid and liquid to obtain desalinated biochar and a salt solution;

[0011] S5: The obtained salt-containing solution is subjected to indirect heating by flue gas to evaporate and crystallize, the salt in the liquid is recovered as a chemical raw material, and the aqueous solution obtained after steam condensation is recycled;

[0012] S6: drying the desalinated biochar obtained in S4, using 50% to 70% of the obtained product as adsorption material or soil improvement material, and recycling 30% to 50% to be used in step S2 as wastewater adsorption and purification material.

[0013] Furthermore, the dehydration method in step S1 is high-pressure mechanical dehydration; preferably, the dehydration method is high-pressure belt filter press dehydration or high-pressure plate and frame filter press dehydration.

[0014] Furthermore, the oil-water separation method in step S2 is a conventional oil-water gravity separation method or a centrifugal separation method; the wastewater is treated by biochar adsorption, and the addition amount is controlled to be a solid-liquid mass ratio of 1:20 to 1:10.

[0015] Furthermore, the biochar after adsorption and purification of wastewater in step S3 is mixed with the solid dehydrated slag obtained in S1, and the mixing time is 10 to 30 minutes; the temperature of the low-temperature pyrolysis treatment is 300° C. to 500° C., and the high-salt biochar is cooled by indirect cooling.

[0016] Furthermore, in the water-soluble process of step S4, the mixing ratio of biochar to water is a solid-liquid mass ratio of 1:5 to 1:10, and the water temperature is 40°C to 80°C; the solid-liquid separation method is centrifugal separation, plate and frame filter press or vacuum filtration.

[0017] Furthermore, the salt-containing solution in step S5 is subjected to indirect heating evaporation and crystallization by flue gas, and the salt in the liquid is recovered as a chemical raw material. The steam is used to preheat the solid phase mixed material treated by low-temperature pyrolysis. The temperature of the aqueous solution obtained after condensation is 40°C to 80°C, and it is recycled as the water-soluble process in step S4.

[0018] Furthermore, in step S6, the temperature of drying the desalinated biochar is 100°C to 160°C.

[0019] Furthermore, the pyrolysis gas generated by carbonization in step S3 is used as energy for the carbonization process, the flue gas generated after combustion of the pyrolysis gas is used as a heat source for the evaporation and crystallization salt extraction device in step S5, and the waste heat of the flue gas tail gas is used for drying the biochar in step S6.

[0020] The present invention also provides a device for the method, characterized in that it mainly comprises a solid-liquid separation device 1# (2), a mixing device (4), a pyrolysis device (6), a cooling device (7), a salt dissolving device (10), a dehydration device (11), a salt extraction device (12), a drying device (13), an exhaust gas purification device (20), an oil-water separation device (23), a purification device (27), and a solid-liquid separation device 2# (28);

[0021] The outlet of the conveying device 1#(1) is connected to the inlet of the solid-liquid separation device 1#(2), the solid phase outlet of the solid-liquid separation device 1#(2) is connected to the inlet of the conveying device 2#(3), and the liquid phase outlet is connected to the inlet of the conveying device 10#(22);

[0022] The outlet of the conveying device 2# (3) is connected to the inlet of the mixing device (4); the outlet of the mixing device (4) is connected to the inlet of the conveying device 3# (5); the outlet of the conveying device 3# (5) is connected to the inlet of the pyrolysis device (6); the outlet of the pyrolysis device (6) is connected to the inlet of the cooling device (7);

[0023] The air outlet of the cooling device (7) is connected to the inlet of the conveying device 5# (9); the outlet of the conveying device 5# (9) is connected to the air inlet of the pyrolysis device (6);

[0024] The material outlet of the cooling device (7) is connected to the inlet of the conveying device 4# (8); the outlet of the conveying device 4# (8) is connected to the inlet of the salt dissolving device (10); the outlet of the salt dissolving device (10) is connected to the inlet of the dehydration device (11);

[0025] The liquid phase outlet of the dehydration device (11) is connected to the inlet of the salt extraction device (12); the solid phase outlet of the dehydration device (11) is connected to the inlet of the drying device (13);

[0026] The outlet 1 of the drying device (13) is connected to the inlet of the conveying device 6# (14); the outlet of the conveying device 6# (14) is connected to the inlet of the purification device (27); the outlet 2 of the drying device (13) is connected to the inlet of the conveying device 7# (15); the outlet of the conveying device 7# (15) is connected to the inlet of the biochar storage bin (16);

[0027] The crystallized salt outlet of the salt extraction device (12) is connected to the inlet of the conveying device 8# (17); the outlet of the conveying device 8# (17) is connected to the inlet of the salt storage bin (18);

[0028] The smoke outlet of the pyrolysis device (6) is connected to the smoke inlet of the salt extraction device (12); the smoke outlet of the salt extraction device (12) is connected to the smoke inlet of the drying device (13); the smoke outlet of the drying device (13) is connected to the smoke inlet of the conveying device 9# (19); the outlet of the conveying device 9# (19) is connected to the smoke inlet of the exhaust gas purification device (20); the smoke outlet of the exhaust gas purification device (20) is connected to the chimney (21);

[0029] The outlet of the conveying device 10# (22) is connected to the inlet of the oil-water separation device (23); the oil outlet of the oil-water separation device (23) is connected to the inlet of the conveying device 11# (24); the outlet of the conveying device 11# (24) is connected to the waste oil storage bin (25);

[0030] The wastewater outlet of the oil-water separation device (23) is connected to the inlet of the conveying device 13# (26); the outlet of the conveying device 13# (26) is connected to the liquid phase inlet of the purification device (27); the outlet of the purification device (27) is connected to the inlet of the solid-liquid separation device 2# (28);

[0031] The solid phase outlet of the solid-liquid separation device 2# (28) is connected to the inlet of the conveying device 13# (29); the outlet of the conveying device 13# (29) is connected to the inlet of the mixing device (4); the liquid phase outlet of the solid-liquid separation device 2# (28) is connected to the inlet of the conveying device 14# (30); the outlet of the conveying device 14# (30) is connected to the water storage tank (31);

[0032] The steam outlet of the salt extraction device (12) is connected to the steam inlet of the mixing device (4); the condensed water outlet of the mixing device (4) is connected to the inlet of the conveying device 15# (32); the outlet of the conveying device 15# (32) is connected to the inlet of the water storage device (33); the outlet of the water storage device (33) is connected to the inlet of the conveying device 16# (34); and the outlet of the conveying device 16# (34) is connected to the inlet of the salt dissolving device (10).

[0033] The pyrolysis gas outlet of the pyrolysis device (6) is directly connected to the furnace of the pyrolysis device (6), the energy generated by the combustion of the pyrolysis gas is used for the pyrolysis device (6), the hot flue gas generated by the pyrolysis device (6) is used for the salt extraction device (12), and the flue gas exhaust energy generated by the salt extraction device (12) is used for the drying device (13).

[0034] Further: the conveying device 1#(1) is a slurry pump;

[0035] The solid-liquid separation device 1# (2) and the solid-liquid separation device 2# (28) are plate-and-frame filter presses or belt filter presses;

[0036] Conveying device 2#(3), conveying device 3#(5), conveying device 4#(8), conveying device 8#(17), and conveying device 13#(29) are high-angle belt conveyors, scraper conveyors, bucket elevators, or screw conveyors;

[0037] The mixing device (4) is a ribbon mixer, a plowshare mixer or a double-shaft mixer;

[0038] The pyrolysis device (6) is a drum-type indirect pyrolysis furnace with its own furnace;

[0039] The cooling device (7) is a drum-type indirect cooling device or a spiral indirect cooling device;

[0040] The conveying device 5# (9) is a common fan;

[0041] The salt dissolving device (10) is a common mixed dissolving device;

[0042] The dehydration device (11) is a plate and frame filter press, a centrifugal dehydrator or a belt filter press;

[0043] The salt extraction device (12) is a drum-type indirect heating evaporation salt extraction device;

[0044] The drying device (13) is a drum drying device, a belt drying device or a disc drying device;

[0045] Conveying device 6# (14) and conveying device 7# (15) are pneumatic conveyors, high-angle belt conveyors, scraper conveyors, bucket elevators or screw conveyors;

[0046] The biochar storage bin (16), the salt storage bin (18) and the waste oil storage bin (25) are ordinary steel bins;

[0047] The conveying device 9# (19) is a common flue gas fan;

[0048] The tail gas purification device (20) is a dry, semi-dry or wet tail gas purification device;

[0049] The chimney (21) is a steel chimney, a brick-concrete chimney or a concrete chimney;

[0050] Conveying device 10# (22), conveying device 13# (26), conveying device 14# (30), conveying device 15# (32), and conveying device 16# (34) are water pumps;

[0051] The oil-water separation device (23) is a gravity type or centrifugal type oil-water separation device;

[0052] The conveying device 11# (24) is an oil pump;

[0053] The purification device (27) is a static adsorption device or a dynamic adsorption column;

[0054] The water tank (31) and the water storage device (33) are ordinary steel tanks or concrete water tanks.

[0055] The method and system for comprehensive treatment of restaurant waste described in the present invention utilize restaurant waste as raw materials, separate and recover waste oil and waste salt as chemical raw materials; the recovered purified water is used as water for greening, and the biochar is used as an adsorption material and soil improvement material, fully realizing the high-value utilization of by-products in the restaurant waste disposal process.

[0056] After the biochar of the present invention adsorbs salt, COD, oil and other components, it is mixed with kitchen filter press solid residue for pyrolysis, which improves the pore structure of the biochar, decomposes organic matter, and leaves salt in the biochar, laying a foundation for subsequent salt extraction.

[0057] The method for treating kitchen waste described in the present invention can achieve complete elimination of harmful substances (such as bacteria, microorganisms and antibiotic pollutants), effective solidification of heavy metals, and a clean and environmentally friendly process. Most existing kitchen waste is treated by anaerobic fermentation to produce biogas that can be used as energy, but the process produces a large amount of biogas residue and biogas liquid, and there is no reasonable large-scale utilization plan. The advantages of the present invention are that it can achieve efficient resource utilization of kitchen waste and is highly practical, specifically including:

[0058] (1) It can achieve rapid and large-scale reduction of restaurant kitchen waste with large processing capacity and high efficiency.

[0059] (2) Salt is obtained from food waste as a chemical raw material to avoid salt loss and pollution; wastewater is used for greening after adsorption and purification, achieving low-cost treatment and utilization of wastewater resources.

[0060] (3) The biochar obtained by extracting salt has rich pore structures and functional groups and good adsorption properties. It can be used to adsorb and purify salt, ammonia nitrogen, COD, etc. in wastewater, and can also be used to adsorb pollutants such as organic matter and heavy metals in wastewater. At the same time, biochar is rich in N, P, K and other elements, and is a good biological fertilizer and soil improvement material.

[0061] (4) It effectively solves the problems existing in the treatment and disposal of food waste, has high treatment efficiency and low cost, and realizes the high-value utilization of by-product classification.

[0062] In the pyrolysis carbonization step, the temperature is 300℃-500℃. This is because this temperature range can achieve complete decomposition of the solid phase and completely eliminate bacteria, microorganisms and antibiotic pollutants. When the temperature is lower than 300℃, not only can the complete pyrolysis of the solid phase not be achieved smoothly, but also the bacteria, microorganisms and antibiotic pollutants contained therein cannot be eliminated; when it is higher than 500℃, it has limited effect on improving the quality of pyrolysis biochar, and it is very easy to cause the calcium-based components to decompose and dissolve in water, thereby affecting the subsequent salt recovery efficiency and easily causing energy waste. The desalinated biochar drying temperature is 80℃-120℃, because the temperature is higher than 120℃, which wastes energy, and the temperature is lower than 80℃, which affects the drying efficiency.

[0063] Beneficial effects: The comprehensive treatment method for kitchen waste of the present invention meets the increasingly urgent demand for kitchen waste treatment and disposal in my country, effectively solves the problems existing in kitchen waste treatment and disposal, has high treatment efficiency and low cost, and realizes high-value utilization of by-product classification, low-carbon, efficient and clean utilization of various by-products, achieves the goal of making the best use of resources, energy saving and environmental protection, and cost reduction, and has good economic and environmental benefits. The device and method provided by the present invention can not only completely solve the environmental pollution problem of kitchen waste, but also realize 100% resource recycling and 100% energy self-supply, and has good economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 It is a connection schematic diagram of a comprehensive kitchen waste treatment device system provided by the present invention.

[0065] Among them: 1. Conveying device 1#, 2. Solid-liquid separation device 1#, 3. Conveying device 2#, 4. Mixing device, 5. Conveying device 3#, 6. Pyrolysis device, 7. Cooling device, 8. Conveying device 4#, 9. Conveying device 5#, 10. Salt dissolving device, 11. Dehydration device, 12. Salt extraction device, 13. Drying device, 14. Conveying device 6#, 15. Conveying device 7#, 16. Biochar storage bin, 17. Conveying device 8#, 18. Salt storage bin , 19. Conveying device 9#, 20. Exhaust gas purification device, 21. Chimney, 22. Conveying device 10#, 23. Oil-water separation device, 24. Conveying device 11#, 25. Waste oil storage bin, 26. Conveying device 12#, 27. Purification device, 28. Solid-liquid separation device 2#, 29. Conveying device 13#, 30. Conveying device 14#, 31. Water storage tank, 32. Conveying device 15#, 33. Water storage device, 34. Conveying device 16#.

[0066] Figure 2 The present invention provides a method and process for comprehensive treatment of restaurant kitchen waste. DETAILED DESCRIPTION

[0067] Embodiments of the present invention are described in detail below, and the examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by reference to the accompanying drawings are exemplary, are intended to be used to explain the present invention, and are not to be construed as limitations of the present invention. Those who do not indicate specific techniques or conditions in the embodiments are carried out according to the techniques or conditions described in the documents in this area or according to the product specification. Those who do not indicate the manufacturer of reagents or instruments used are all conventional products that can be obtained commercially.

[0068] In the following examples and comparative examples, unless otherwise specified, "%" refers to weight percentage.

[0069] like Figure 1 and 2As shown, the present invention provides a comprehensive treatment method for food waste, comprising the following steps: (1) subjecting food waste to high-pressure dehydration to obtain solid-phase dehydrated residue and dehydrated liquid; (2) subjecting the dehydrated liquid to oil-water separation treatment to obtain grease and wastewater, the grease being recycled as a chemical raw material, and the wastewater being used for greening water after being adsorbed and purified by biochar; (3) mixing the biochar after adsorption and purification of wastewater with the solid-phase dehydrated residue and subjecting it to low-temperature pyrolysis treatment, and cooling it to obtain high-salt biochar; (4) utilizing a water-soluble process to dissolve soluble salts in the biochar, and then subjecting it to solid-liquid separation to obtain desalted biochar and a salt-containing solution; (5) subjecting the salt-containing solution to indirect heating evaporation and crystallization by flue gas, recovering the salt in the liquid as a chemical raw material, and recycling the aqueous solution obtained after steam condensation; (6) drying the desalted biochar, 50% to 70% of the product being used as an adsorption material or soil improvement material, and 30% to 50% being recycled and used in step (2) as a wastewater adsorption and purification material.

[0070] Furthermore, the dehydration method in step (1) is high-pressure mechanical dehydration, including high-pressure belt filter press dehydration or high-pressure plate and frame filter press dehydration.

[0071] Furthermore, the oil-water separation method in step (2) is a conventional oil-water gravity separation method or a centrifugal separation method; the wastewater is treated by biochar adsorption, and the addition amount is controlled to be a solid-liquid mass ratio of 1:20 to 1:10.

[0072] Furthermore, the biochar obtained after adsorption and purification of wastewater in step (3) is mixed with the solid dehydrated slag obtained in step (1) for 10 to 30 minutes; the low-temperature pyrolysis treatment temperature is 300° C. to 500° C., and the high-salt biochar cooling method is indirect cooling.

[0073] Furthermore, in the water-soluble process of step (4), the mixing ratio of biochar to water is a solid-liquid mass ratio of 1:5 to 1:10, and the water temperature is controlled to be 40°C to 80°C; after the soluble salt in the biochar is dissolved, the solid-liquid separation method is centrifugal separation, plate and frame filter press or vacuum filtration to obtain desalted biochar and a salt solution.

[0074] Furthermore, the salt-containing solution in step (5) is subjected to indirect heating by flue gas for evaporation and crystallization, and the salt in the liquid is recovered as a chemical raw material. The steam is used to preheat the solid phase mixture treated by low-temperature pyrolysis. The temperature of the aqueous solution obtained after condensation is 40°C to 80°C, and it is recycled as the water-soluble process in step (4).

[0075] Furthermore, in step (6), the desalinated biochar is dried at a temperature of 100°C to 160°C, 50% to 70% of the obtained product is used as adsorption material or soil improvement material, and 30% to 50% is recycled and used in step (2) as wastewater adsorption and purification material.

[0076] Furthermore, the pyrolysis gas generated by carbonization in step (3) is used as energy for the carbonization process, the flue gas generated after combustion of the pyrolysis gas is used as a heat source for the evaporation and crystallization salt extraction device in step (5), and the waste heat of the flue gas tail gas is used for drying the biochar in step (6).

[0077] Example 1

[0078] A comprehensive kitchen waste treatment system, comprising 1. a conveying device 1#, 2. a solid-liquid separation device 1#, 3. a conveying device 2#, 4. a mixing device, 5. a conveying device 3#, 6. a pyrolysis device, 7. a cooling device, 8. a conveying device 4#, 9. a conveying device 5#, 10. a salt dissolving device, 11. a dehydration device, 12. a salt extraction device, 13. a drying device, 14. a conveying device 6#, 15. a conveying device 7#, 16. a biochar storage bin, 17. a conveying device 8#, 18. Salt storage silo, 19. Conveying device 9#, 20. Exhaust gas purification device, 21. Chimney, 22. Conveying device 10#, 23. Oil-water separation device, 24. Conveying device 11#, 25. Waste oil storage silo, 26. Conveying device 12#, 27. Purification device, 28. Solid-liquid separation device 2#, 29. Conveying device 13#, 30. Conveying device 14#, 31. Water storage tank, 32. Conveying device 15#, 33. Water storage device, 34. Conveying device 16#.

[0079] The outlet of the conveying device 1#(1) is connected to the inlet of the solid-liquid separation device 1#(2), the solid phase outlet of the solid-liquid separation device 1#(2) is connected to the inlet of the conveying device 2#(3), and the liquid phase outlet is connected to the inlet of the conveying device 10#(22);

[0080] The outlet of the conveying device 2# (3) is connected to the inlet of the mixing device (4); the outlet of the mixing device (4) is connected to the inlet of the conveying device 3# (5); the outlet of the conveying device 3# (5) is connected to the inlet of the pyrolysis device (6); the outlet of the pyrolysis device (6) is connected to the inlet of the cooling device (7);

[0081] The air outlet of the cooling device (7) is connected to the inlet of the conveying device 5# (9); the outlet of the conveying device 5# (9) is connected to the air inlet of the pyrolysis device (6);

[0082] The material outlet of the cooling device (7) is connected to the inlet of the conveying device 4# (8); the outlet of the conveying device 4# (8) is connected to the inlet of the salt dissolving device (10); the outlet of the salt dissolving device (10) is connected to the inlet of the dehydration device (11);

[0083] The liquid phase outlet of the dehydration device (11) is connected to the inlet of the salt extraction device (12); the solid phase outlet of the dehydration device (11) is connected to the inlet of the drying device (13);

[0084] The outlet 1 of the drying device (13) is connected to the inlet of the conveying device 6# (14); the outlet of the conveying device 6# (14) is connected to the inlet of the purification device (27); the outlet 2 of the drying device (13) is connected to the inlet of the conveying device 7# (15); the outlet of the conveying device 7# (15) is connected to the inlet of the biochar storage bin (16);

[0085] The crystallized salt outlet of the salt extraction device (12) is connected to the inlet of the conveying device 8# (17); the outlet of the conveying device 8# (17) is connected to the inlet of the salt storage bin (18);

[0086] The smoke outlet of the pyrolysis device (6) is connected to the smoke inlet of the salt extraction device (12); the smoke outlet of the salt extraction device (12) is connected to the smoke inlet of the drying device (13); the smoke outlet of the drying device (13) is connected to the smoke inlet of the conveying device 9# (19); the outlet of the conveying device 9# (19) is connected to the smoke inlet of the exhaust gas purification device (20); the smoke outlet of the exhaust gas purification device (20) is connected to the chimney (21);

[0087] The outlet of the conveying device 10# (22) is connected to the inlet of the oil-water separation device (23); the oil outlet of the oil-water separation device (23) is connected to the inlet of the conveying device 11# (24); the outlet of the conveying device 11# (24) is connected to the waste oil storage bin (25);

[0088] The wastewater outlet of the oil-water separation device (23) is connected to the inlet of the conveying device 13# (26); the outlet of the conveying device 13# (26) is connected to the liquid phase inlet of the purification device (27); the outlet of the purification device (27) is connected to the inlet of the solid-liquid separation device 2# (28);

[0089] The solid phase outlet of the solid-liquid separation device 2# (28) is connected to the inlet of the conveying device 13# (29); the outlet of the conveying device 13# (29) is connected to the inlet of the mixing device (4); the liquid phase outlet of the solid-liquid separation device 2# (28) is connected to the inlet of the conveying device 14# (30); the outlet of the conveying device 14# (30) is connected to the water storage tank (31);

[0090] The steam outlet of the salt extraction device (12) is connected to the steam inlet of the mixing device (4); the condensed water outlet of the mixing device (4) is connected to the inlet of the conveying device 15# (32); the outlet of the conveying device 15# (32) is connected to the inlet of the water storage device (33); the outlet of the water storage device (33) is connected to the inlet of the conveying device 16# (34); and the outlet of the conveying device 16# (34) is connected to the inlet of the salt dissolving device (10).

[0091] The pyrolysis gas outlet of the pyrolysis device (6) is directly connected to the furnace of the pyrolysis device (6), the energy generated by the combustion of the pyrolysis gas is used for the pyrolysis device (6), the hot flue gas generated by the pyrolysis device (6) is used for the salt extraction device (12), and the flue gas exhaust energy generated by the salt extraction device (12) is used for the drying device (13).

[0092] The conveying device 1#(1) is a slurry pump;

[0093] The solid-liquid separation device 1# (2) and the solid-liquid separation device 2# (28) are plate-and-frame filter presses or belt filter presses;

[0094] Conveying device 2#(3), conveying device 3#(5), conveying device 4#(8), conveying device 8#(17), and conveying device 13#(29) are high-angle belt conveyors, scraper conveyors, bucket elevators, or screw conveyors;

[0095] The mixing device (4) is a ribbon mixer, a plowshare mixer or a double-shaft mixer;

[0096] The pyrolysis device (6) is a drum-type indirect pyrolysis furnace with its own furnace;

[0097] The cooling device (7) is a drum-type indirect cooling device or a spiral indirect cooling device;

[0098] The conveying device 5# (9) is a common fan;

[0099] The salt dissolving device (10) is a common mixed dissolving device;

[0100] The dehydration device (11) is a plate and frame filter press, a centrifugal dehydrator or a belt filter press;

[0101] The salt extraction device (12) is a drum-type indirect heating evaporation salt extraction device;

[0102] The drying device (13) is a drum drying device, a belt drying device or a disc drying device;

[0103] Conveying device 6# (14) and conveying device 7# (15) are pneumatic conveyors, high-angle belt conveyors, scraper conveyors, bucket elevators or screw conveyors;

[0104] The biochar storage bin (16), the salt storage bin (18) and the waste oil storage bin (25) are ordinary steel bins;

[0105] The conveying device 9# (19) is a common flue gas fan;

[0106] The tail gas purification device (20) is a dry, semi-dry or wet tail gas purification device;

[0107] The chimney (21) is a steel chimney, a brick-concrete chimney or a concrete chimney;

[0108] Conveying device 10# (22), conveying device 13# (26), conveying device 14# (30), conveying device 15# (32), and conveying device 16# (34) are water pumps;

[0109] The oil-water separation device (23) is a gravity type or centrifugal type oil-water separation device;

[0110] The conveying device 11# (24) is an oil pump;

[0111] The purification device (27) is a static adsorption device or a dynamic adsorption column;

[0112] The water tank (31) and the water storage device (33) are ordinary steel tanks or concrete water tanks.

[0113] When in operation, the food waste is transported by the conveying device 1#(1) to the solid-liquid separation device 1#(2) for solid-liquid separation. The separated solid phase is transported by the conveying device 2#(3) to the mixing device (4) to be mixed with the material transported by the conveying device 13#(29). The mixture is transported by the conveying device 3#(5) to the pyrolysis device (6) for anaerobic pyrolysis. The pyrolysis product enters the cooling device (7) for indirect cooling by air. The biochar obtained by cooling is transported by the conveying device 4#(8) to the salt dissolving device ( 10), the salt in the biochar is dissolved and then dehydrated to obtain a salt solution which enters the salt extraction device (12) for evaporation and salt extraction; the obtained solid is dried in the drying device (13) to obtain a desalted biochar product; a portion of the desalted biochar product is transported to the biochar storage bin (16) via the conveying device 7# (15) for storage and used as soil improvement or adsorption material; the other portion is transported to the purification device (27) via the conveying device 6# (14) as an adsorption and purification material for COD, salt and the like in wastewater. The salt extraction device (12) is an indirect heating evaporation crystallization salt extraction device, which uses the hot flue gas generated by the pyrolysis device (6) as energy, and the water vapor generated by the steam is used for indirect heating of the mixing device, and the condensed water with a certain temperature is transported to the water storage device (33) via the conveying device 15# (32) for storage, and then transported to the salt extraction device (12) via the conveying device 16# (34) for recycling.

[0114] The pyrolysis gas generated by the pyrolysis device (6) is burned in the furnace of the pyrolysis device to provide heat for the pyrolysis device; the cold air indirectly heated by the cooling device (7) is transported by the conveying device 5# (9) to the furnace of the pyrolysis device (6) for use as air required for combustion; the hot flue gas generated is used to indirectly heat the heat source of the salt extraction device (12), and then enters the drying device (13) as a drying energy source, and the flue gas exhaust is then transported by the conveying device 9# (19) to the exhaust gas purification device (20) for purification treatment, and finally discharged through the chimney (21) to meet the emission standards.

[0115] The liquid phase separated by the solid-liquid separation device 1# (2) is transported to the oil-water separation device (23) via the transport device 10# (22); the separated oil is transported to the waste oil storage bin (25) via the transport device 11# (24) for storage and use as a chemical raw material; the separated wastewater is transported to the purification device (27) via the transport device 13# (26) and mixed with the desalinated biochar transported by the transport device 6# (14) to achieve adsorption purification treatment; the solid-liquid mixture after purification enters the solid-liquid separation device 2# (28) to achieve solid-liquid separation, and the solid biochar is transported to the mixing device (4) via the transport device 13# (29) for mixing for subsequent pyrolysis, so as to achieve complete decomposition of organic pollutants such as COD. The aqueous solution separated by the solid-liquid separation device 2# (28) is transported to the water storage tank (31) via the transport device 14# (30) for storage and use as greening water.

[0116] Using the above process, the recovery rate of sodium chloride in food waste is >90%; the specific surface area of ​​the obtained desalinated biochar is >300m 2 / g, the adsorption removal rate of organic pollutants in wastewater is>95%, and the adsorption removal rate of heavy metals in wastewater is>95%.

[0117] To sum up, through the comprehensive treatment of food waste, four types of products, namely oil, green water, salt and biochar, are obtained, the resource-based, large-scale and rapid treatment of food waste is achieved, and various by-products are obtained in a low-carbon, efficient and clean manner, achieving the goals of making full use of resources, saving energy and protecting the environment, and reducing costs.

[0118] Example 2 Application method of the comprehensive treatment system for restaurant kitchen waste

[0119] like Figure 2 As shown. The following steps are included:

[0120] (1) The kitchen waste is passed through 1. conveying device 1#, and enters 2. solid-liquid separation device 1# for high-pressure dehydration, and then enters 23. oil-water separation device through 22. conveying device 10# to obtain solid phase dehydrated residue and dehydrated liquid; the dehydration method is high-pressure mechanical dehydration, including high-pressure belt filter press dehydration or high-pressure plate and frame filter press dehydration.

[0121] (2) The dehydrated liquid is subjected to oil-water separation treatment (23. Oil-water separation device) to obtain oil (entering 25. waste oil storage bin through 24. conveying device 11#) and wastewater. The oil is recycled as a chemical raw material. The wastewater (entering 27. purification device through 26. conveying device 12#) is purified by biochar adsorption and then subjected to solid-liquid separation by 28. solid-liquid separation device 2#. The obtained liquid phase is conveyed to 31. water storage tank through 30. conveying device 14# and used as water for greening. The oil-water separation method is a conventional oil-water gravity separation method or a centrifugal separation method. The wastewater is treated by biochar adsorption, and the amount of biochar added is controlled to be a solid-liquid mass ratio of 1:20 to 1:10.

[0122] (3) The biochar used for adsorption and purification of wastewater is separated by 28. solid-liquid separation device 2# to obtain used biochar, which is transported to 4. mixing device via 29. conveying device 13# and mixed with solid dehydrated slag (mixing time is 10 to 30 minutes). The mixture is transported to 6. pyrolysis device via 5. conveying device 3# for anaerobic low-temperature pyrolysis. The pyrolysis product enters 7. cooling device for indirect cooling with air. The low-temperature pyrolysis treatment temperature is 300°C to 500°C, and high-salt biochar is obtained after indirect cooling.

[0123] (4) The high-salt biochar is transported to the salt dissolving device 10 through the transport device 4# of 8. The soluble salt in the biochar is dissolved by a water-soluble process (wherein the mixing ratio of biochar to water is 1:5 to 1:10 by solid-liquid mass ratio, and the water temperature is controlled at 40°C to 80°C). Then, the solid-liquid separation (centrifugal separation, plate and frame filter press or vacuum filtration) is performed to obtain desalted biochar and a salt solution.

[0124] (5) The salt solution is sent to the salt extraction device 12, and the salt in the liquid is recovered as a chemical raw material by indirect heating evaporation and crystallization with flue gas. The aqueous solution obtained after steam condensation is recycled; the steam is used to preheat the solid phase mixed material treated by low-temperature pyrolysis (4. In the mixing device), and the temperature of the aqueous solution obtained after condensation is 40°C to 80°C, which is recycled as the water-soluble process in step (4).

[0125] (6) drying the desalinated biochar (a portion is transported through 13. drying device via 15. conveying device 7# into 16. biochar storage bin; the other portion is transported through conveying device 6# (14) into purification device (27) as wastewater adsorption and purification material) (drying temperature is 100°C to 160°C), 50% to 70% of the biochar product is used as adsorption material or soil improvement material, and 30% to 50% is recycled and used in step (2) as wastewater adsorption and purification material.

[0126] Furthermore, the pyrolysis gas generated by carbonization in step (3) is used as energy for the carbonization process, the flue gas generated after combustion of the pyrolysis gas is used as a heat source for the evaporation and crystallization salt extraction device in step (5), and the waste heat of the flue gas tail gas is used for drying the biochar in step (6).

[0127] The method described in this embodiment can achieve efficient and large-scale disposal and resource utilization of restaurant kitchen waste, with a reduction rate of >85%, a soluble salt recovery rate of >90%, and the obtained biochar (N+P2O5+K2O)>5%. The treatment system achieves 100% self-sufficiency in energy, is clean and environmentally friendly, and the biochar is suitable for soil improvement, which can increase crop yields by >15%, and has good economic and environmental benefits.

[0128] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A method for comprehensive treatment of food waste, characterized in that: The following steps are included: S1: Dehydrating the kitchen waste under high pressure to obtain solid dehydrated residue and dehydrated liquid; S2: The dehydrated liquid is subjected to oil-water separation treatment to obtain oil and wastewater, wherein the oil is recycled as a chemical raw material, and the wastewater is used for greening water after being purified by biochar adsorption; S3: the biochar after adsorption and purification of wastewater is mixed with the solid dehydrated slag obtained in S1 and subjected to low-temperature pyrolysis treatment, and high-salt biochar is obtained after cooling; the temperature of the low-temperature pyrolysis treatment is 300° C. to 500° C.; S4: using a water-soluble process to dissolve the soluble salt in the obtained high-salt biochar, and then separating the solid and liquid to obtain desalinated biochar and a salt solution; S5: The obtained salt-containing solution is subjected to indirect heating by flue gas to evaporate and crystallize, the salt in the liquid is recovered as a chemical raw material, and the aqueous solution obtained after steam condensation is recycled; S6: drying the desalinated biochar obtained in S4, using 50% to 70% of the obtained product as adsorption material or soil improvement material, and recycling 30% to 50% to be used in step S2 as wastewater adsorption and purification material.

2. The method for comprehensive treatment of food waste according to claim 1, characterized in that: The dehydration method in step S1 is high-pressure mechanical dehydration.

3. The method for comprehensive treatment of food waste as claimed in claim 2, characterized in that: The dehydration method is high-pressure belt filter press dehydration or high-pressure plate and frame filter press dehydration.

4. The method for comprehensive treatment of food waste according to claim 1, characterized in that: The oil-water separation method in step S2 is a conventional oil-water gravity separation method or a centrifugal separation method; the wastewater is treated by biochar adsorption, and the addition amount is controlled to be a solid-liquid mass ratio of 1:20 to 1:

10.

5. The method for comprehensive treatment of food waste according to claim 1, characterized in that: The biochar after adsorption and purification of wastewater in step S3 is mixed with the solid dehydrated slag obtained in step S1, and the mixing time is 10 to 30 minutes; the high-salt biochar is cooled by indirect cooling.

6. The method for comprehensive treatment of food waste according to claim 1, characterized in that: In the water-soluble process of step S4, the mixing ratio of biochar to water is 1:5 to 1:10 by solid-liquid mass ratio, and the water temperature is 40°C to 80°C; the solid-liquid separation method is centrifugal separation, plate and frame filter press or vacuum filtration.

7. The method for comprehensive treatment of food waste according to claim 1, characterized in that: The salt-containing solution in step S5 is evaporated and crystallized by indirect heating with flue gas, and the salt in the liquid is recovered as a chemical raw material. The steam is used to preheat the solid phase mixed material treated by low-temperature pyrolysis. The temperature of the aqueous solution obtained after condensation is 40°C to 80°C, and it is recycled as the water-soluble process in step S4.

8. The method for comprehensive treatment of food waste according to claim 1, characterized in that: The temperature of drying the desalinated biochar in step S6 is 100°C to 160°C.

9. The method for comprehensive treatment of food waste according to claim 1, characterized in that: The pyrolysis gas generated by carbonization in step S3 is used as energy for the carbonization process, the flue gas generated after combustion of the pyrolysis gas is used as a heat source for the evaporation and crystallization salt extraction device in step S5, and the waste heat of the flue gas tail gas is used for drying the biochar in step S6.

10. A device for the method according to any one of claims 1 to 9, characterized in that: It comprises a solid-liquid separation device 1# (2), a mixing device (4), a pyrolysis device (6), a cooling device (7), a salt dissolving device (10), a dehydration device (11), a salt extraction device (12), a drying device (13), an exhaust gas purification device (20), an oil-water separation device (23), a purification device (27), and a solid-liquid separation device 2# (28); The outlet of the conveying device 1#(1) is connected to the inlet of the solid-liquid separation device 1#(2), the solid phase outlet of the solid-liquid separation device 1#(2) is connected to the inlet of the conveying device 2#(3), and the liquid phase outlet is connected to the inlet of the conveying device 10#(22); The outlet of the conveying device 2# (3) is connected to the inlet of the mixing device (4); the outlet of the mixing device (4) is connected to the inlet of the conveying device 3# (5); the outlet of the conveying device 3# (5) is connected to the inlet of the pyrolysis device (6); the outlet of the pyrolysis device (6) is connected to the inlet of the cooling device (7); The air outlet of the cooling device (7) is connected to the inlet of the conveying device 5# (9); the outlet of the conveying device 5# (9) is connected to the air inlet of the pyrolysis device (6); The material outlet of the cooling device (7) is connected to the inlet of the conveying device 4# (8); the outlet of the conveying device 4# (8) is connected to the inlet of the salt dissolving device (10); the outlet of the salt dissolving device (10) is connected to the inlet of the dehydration device (11); The liquid phase outlet of the dehydration device (11) is connected to the inlet of the salt extraction device (12); the solid phase outlet of the dehydration device (11) is connected to the inlet of the drying device (13); The outlet 1 of the drying device (13) is connected to the inlet of the conveying device 6# (14); the outlet of the conveying device 6# (14) is connected to the inlet of the purification device (27); the outlet 2 of the drying device (13) is connected to the inlet of the conveying device 7# (15); the outlet of the conveying device 7# (15) is connected to the inlet of the biochar storage bin (16); The crystallized salt outlet of the salt extraction device (12) is connected to the inlet of the conveying device 8# (17); the outlet of the conveying device 8# (17) is connected to the inlet of the salt storage bin (18); The smoke outlet of the pyrolysis device (6) is connected to the smoke inlet of the salt extraction device (12); the smoke outlet of the salt extraction device (12) is connected to the smoke inlet of the drying device (13); the smoke outlet of the drying device (13) is connected to the smoke inlet of the conveying device 9# (19); the outlet of the conveying device 9# (19) is connected to the smoke inlet of the exhaust gas purification device (20); the smoke outlet of the exhaust gas purification device (20) is connected to the chimney (21); The outlet of the conveying device 10# (22) is connected to the inlet of the oil-water separation device (23); the oil outlet of the oil-water separation device (23) is connected to the inlet of the conveying device 11# (24); the outlet of the conveying device 11# (24) is connected to the waste oil storage bin (25); The wastewater outlet of the oil-water separation device (23) is connected to the inlet of the conveying device 13# (26); the outlet of the conveying device 13# (26) is connected to the liquid phase inlet of the purification device (27); the outlet of the purification device (27) is connected to the inlet of the solid-liquid separation device 2# (28); The solid phase outlet of the solid-liquid separation device 2# (28) is connected to the inlet of the conveying device 13# (29); the outlet of the conveying device 13# (29) is connected to the inlet of the mixing device (4); the liquid phase outlet of the solid-liquid separation device 2# (28) is connected to the inlet of the conveying device 14# (30); the outlet of the conveying device 14# (30) is connected to the water storage tank (31); The steam outlet of the salt extraction device (12) is connected to the steam inlet of the mixing device (4); the condensed water outlet of the mixing device (4) is connected to the inlet of the conveying device 15# (32); the outlet of the conveying device 15# (32) is connected to the inlet of the water storage device (33); the outlet of the water storage device (33) is connected to the inlet of the conveying device 16# (34); the outlet of the conveying device 16# (34) is connected to the inlet of the salt dissolving device (10); The pyrolysis gas outlet of the pyrolysis device (6) is directly connected to the furnace of the pyrolysis device (6), the energy generated by the combustion of the pyrolysis gas is used for the pyrolysis device (6), the hot flue gas generated by the pyrolysis device (6) is used for the salt extraction device (12), and the flue gas exhaust energy generated by the salt extraction device (12) is used for the drying device (13).

11. The device according to claim 10, characterized in that: The conveying device 1#(1) is a slurry pump; The solid-liquid separation device 1# (2) and the solid-liquid separation device 2# (28) are plate-and-frame filter presses or belt filter presses; Conveying device 2#(3), conveying device 3#(5), conveying device 4#(8), conveying device 8#(17), and conveying device 13#(29) are high-angle belt conveyors, scraper conveyors, bucket elevators, or screw conveyors; The mixing device (4) is a ribbon mixer, a plowshare mixer or a double-shaft mixer; The pyrolysis device (6) is a drum-type indirect pyrolysis furnace with its own furnace; The cooling device (7) is a drum-type indirect cooling device or a spiral indirect cooling device; The conveying device 5# (9) is a common fan; The salt dissolving device (10) is a common mixed dissolving device; The dehydration device (11) is a plate and frame filter press, a centrifugal dehydrator or a belt filter press; The salt extraction device (12) is a drum-type indirect heating evaporation salt extraction device; The drying device (13) is a drum drying device, a belt drying device or a disc drying device; Conveying device 6# (14) and conveying device 7# (15) are pneumatic conveyors, high-angle belt conveyors, scraper conveyors, bucket elevators or screw conveyors; The biochar storage bin (16), the salt storage bin (18) and the waste oil storage bin (25) are ordinary steel bins; The conveying device 9# (19) is a common flue gas fan; The tail gas purification device (20) is a dry, semi-dry or wet tail gas purification device; The chimney (21) is a steel chimney, a brick-concrete chimney or a concrete chimney; Conveying device 10# (22), conveying device 13# (26), conveying device 14# (30), conveying device 15# (32), and conveying device 16# (34) are water pumps; The oil-water separation device (23) is a gravity type or centrifugal type oil-water separation device; The conveying device 11# (24) is an oil pump; The purification device (27) is a static adsorption device or a dynamic adsorption column; The water tank (31) and the water storage device (33) are ordinary steel tanks or concrete water tanks.

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