A domestic waste landfill site excavation, screening, washing and cracking system and a working method thereof

Abstract

The present application provides a kind of domestic waste landfill excavation screening water washing cracking system and its working method, and domestic waste landfill excavation screening water washing cracking produces cracking oil, carbon powder, cracking gas, relative to the direct combustion into incinerator in the past, not only reduce carbon emissions, and three have higher secondary utilization value, can be used to make up the cost of excavation screening.Sieving system includes drum screen, plastic separator, screen conveyor, screen magnetic separator, air separator, screen magnetic separator, drum screen, iron metal buffer bin, humus buffer bin, aggregate buffer bin and light material buffer bin;Washing system includes cleaning pool, salvage machine, crusher, strong washing machine, plastic packing machine, sediment clean water pool, sewage pool, centrifugal dehydrator and sludge plate frame filter press;Cracking system includes yard, loader, cracking device, hot blast furnace, oil-gas separation mechanism, oil tank and carbon powder packing machine.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of domestic waste landfill excavation screening water washing pyrolysis system and working method thereof. BACKGROUND

[0002] Before the construction of waste incineration power plant, most cities use landfill to dispose garbage, which also leads to the landfill operation of most cities for a long time. Because landfill was built early, the technical level, construction level and material quality are relatively backward. In recent years, harmful events such as odor, groundwater pollution and landslides caused by old landfill have occurred frequently.

[0003] With the continuous improvement of waste incineration power plant construction, domestic waste generated in the city can be completely consumed in the waste incineration plant, and does not need to enter the landfill again, so more and more landfills will be idle.

[0004] According to the requirements of "Fourteenth Five-Year" Urban Domestic Waste Classification and Treatment Facilities Development Plan", to prevent problems from happening, a large number of landfills will be gradually excavated, treated and ecologically restored.

[0005] For landfills with serious leakage, overall excavation is required. After most landfills are excavated, the screening mode is used to package the light material on the screen into the incineration plant for incineration. However, the light material on the screen contains a large amount of plastic, which directly uses incineration, not only needs to pay for incineration treatment, increases the pressure of flue gas treatment of incineration plant, but also increases carbon emissions.

[0006] According to statistics, there are about 1960 domestic waste landfills in China, with a stock of 8 billion tons of garbage and an area of 550 million square meters. The landfill contains various substances, and the composition of several domestic landfills is shown in the table below:

[0007]

[0008] Among them, the proportion of rubber and plastic is about 15%-28%, about 20% on average. If it can be utilized, there will be 1.6 billion tons. SUMMARY

[0009] The purpose of the present application is to overcome the above-mentioned deficiencies in the prior art, and to provide a domestic waste landfill excavation screening water washing pyrolysis system and working method thereof with reasonable structure design. The pyrolysis oil, carbon powder and pyrolysis gas produced after the domestic waste landfill excavation screening water washing pyrolysis are relatively directly burned into the incineration plant, not only reducing carbon emissions, but also having high secondary utilization value, which can be used to offset the cost of excavation and screening.

[0010] The invention solves the above problems by adopting the technical scheme of a household garbage landfill site excavation, screening, water washing and cracking system, characterized by comprising an excavation system, a screening system, a water washing system and a cracking system.

[0011] The screening system comprises a uniform material conveyor, a first-stage roller screen, a plastic separator, a screen-over conveyor, a plastic conveyor, a screen-over magnetic separator, an air separator, a screen-under conveyor, a screen-under magnetic separator, a second-stage roller screen, an iron metal buffer bin, a ferromagnetic metal collection conveyor, a humus soil buffer bin, a humus soil conveyor, an aggregate collection conveyor, an aggregate buffer bin, a light material collection conveyor and a light material buffer bin; the water washing system comprises a first cleaning pool, a first material salvaging machine, a crusher, a second cleaning pool, a second material salvaging machine, a strong washing machine, a third cleaning pool, a plastic packing machine, a sediment clean water pool, a sewage pool, a centrifugal dehydrator and a sludge plate-and-frame filter press; and the cracking system comprises a stockyard, a loader, a feeding conveyor, a cracking device, a hot blast furnace, an oil-gas separation mechanism, an oil tank and a carbon powder packing machine.

[0012] The excavation system cooperates with the uniform material conveyor.

[0013] The uniform material conveyor is connected with the inlet of the first-stage roller screen; the screen-over outlet of the first-stage roller screen is connected with the inlet of the plastic separator, and the light material outlet of the plastic separator is connected with the first cleaning pool through the plastic conveyor; the screen-under outlet of the first-stage roller screen is connected with the inlet of the second-stage roller screen through the screen-under belt; the screen-under outlet of the second-stage roller screen is connected with the humus soil buffer bin through the humus soil conveyor; the screen-over outlet of the second-stage roller screen is connected with the aggregate buffer bin through the aggregate collection conveyor; the heavy material outlet of the plastic separator is connected with the inlet of the air separator through the screen-over conveyor; the heavy material outlet of the air separator is connected with the aggregate buffer bin through the aggregate collection conveyor; the light material outlet of the air separator is connected with the light material buffer bin through the light material collection conveyor; the screen-over magnetic separator is arranged on the screen-over conveyor, and the screen-under magnetic separator is arranged on the screen-under conveyor; the screen-over magnetic separator and the screen-under magnetic separator are connected with the iron metal buffer bin through the ferromagnetic metal collection conveyor.

[0014] The first cleaning pool is connected with the first material salvaging machine; the first material salvaging machine is connected with the inlet of the crusher; the outlet of the crusher is connected with the second cleaning pool; the second cleaning pool is connected with the second material salvaging machine; the second material salvaging machine is connected with the inlet of the strong washing machine; the outlet of the strong washing machine is connected with the third cleaning pool; the third cleaning pool is connected with the plastic packing machine; the first cleaning pool, the second cleaning pool and the third cleaning pool are all provided with cleaning water outlets and water supplementing inlets; the cleaning water outlets of the first cleaning pool, the second cleaning pool and the third cleaning pool are all connected with the inlet of the sewage pool; the outlet of the sewage pool is connected with the inlet of the centrifugal dehydrator; the water outlet of the centrifugal dehydrator is connected with the inlet of the sediment clean water pool; the outlet of the sediment clean water pool is connected with the water supplementing inlets of the first cleaning pool, the second cleaning pool and the third cleaning pool; the sludge outlet of the centrifugal dehydrator is connected with the inlet of the sludge plate-frame filter press.

[0015] The plastic packing machine is matched with the stockyard; the loading vehicle is matched with the stockyard and the feeding conveyor; the feeding conveyor is connected with the inlet of the cracking device; the oil gas outlet of the cracking device is connected with the inlet of the oil gas separation mechanism; the carbon powder outlet of the cracking device is connected with the carbon powder packing machine; the cracking oil outlet of the oil gas separation mechanism is connected with the oil tank; the cracking gas outlet of the oil gas separation mechanism is connected with the fuel inlet of the hot blast furnace; the flue gas outlet of the hot blast furnace is connected with the cracking device.

[0016] The excavation system comprises a garbage excavator, a loading vehicle, a drying and temporary storage greenhouse and a forklift; the garbage excavator is matched with the loading vehicle; the loading vehicle is matched with the drying and temporary storage greenhouse; the forklift is matched with the drying and temporary storage greenhouse; the forklift is matched with the material conveying conveyor.

[0017] The bottom of the first cleaning pool, the second cleaning pool and the third cleaning pool is provided with a residue discharging device.

[0018] The water washing system further comprises a dosing room, and the dosing room is connected with the sediment clean water pool.

[0019] The water outlet of the sludge plate-frame filter press is connected with the inlet of the sediment clean water pool.

[0020] The cracking system further comprises a flue gas purification device, and the flue gas purification device is connected with the cracking device.

[0021] The oil gas separation mechanism comprises a first oil gas separator and a second oil gas separator; the oil gas outlet of the cracking device is connected with the inlet of the first oil gas separator; the outlet of the first oil gas separator is connected with the inlet of the second oil gas separator; the cracking oil outlet of the second oil gas separator is connected with the oil tank; the cracking gas outlets of the first oil gas separator and the second oil gas separator are connected with the fuel inlet of the hot blast furnace.

[0022] The carbon powder outlet of the cracking device is connected with the carbon powder packing machine through a carbon powder discharging screw conveyor.

[0023] The working method of a domestic waste landfill excavation screening and water washing and cracking system, characterized by comprising the following steps:

[0024] (1) Screening process: the garbage excavated by the excavation system in the domestic waste landfill is fed to the uniform material conveyor, and the screening system finally screens out five categories of plastic, humus, aggregate, light material and iron metal; the screening process specifically comprises the following steps:

[0025] (1-1) Plastic: the uniform material conveyor is fed into the first-stage cylinder screen, the screen material is fed into the plastic separator, and the plastic separated by the plastic separator is sent to the water washing system through the plastic conveyor;

[0026] (1-2) Humus: the undersize material of the first-stage cylinder screen is fed into the second-stage cylinder screen through the undersize material belt, and the undersize material of the second-stage cylinder screen is fed into the humus buffer bin through the humus conveyor;

[0027] (1-3) Aggregate: the oversize material of the second-stage cylinder screen is fed into the aggregate buffer bin through the aggregate collection conveyor, and the heavy material separated in the plastic separator is fed into the air separator through the oversize material conveyor, and the heavy material after air separation is fed into the aggregate buffer bin through the aggregate collection conveyor;

[0028] (1-4) Light material: the light material after air separation of the air separator is fed into the light material buffer bin through the light material collection conveyor;

[0029] (-15) Iron metal: the metal after magnetic separation of the oversize material magnetic separator and the undersize material magnetic separator is fed into the iron metal buffer bin through the ferromagnetic metal collection conveyor;

[0030] (2) Water washing process: the plastic in the screening system is sent to the first washing pool through the plastic conveyor, the plastic in the first washing pool is fished out and sent to the crusher through the first fishing machine, and after crushing, it is sent to the second washing pool, the plastic in the second washing pool is fished out and sent to the strong washing machine through the second fishing machine, the plastic is washed clean and then sent to the third washing pool, and the plastic after the last washing is sent to the plastic packing machine;

[0031] After washing the first washing pool, the second washing pool and the third washing pool, the water in the first washing pool, the second washing pool and the third washing pool is pumped into the sewage pool, and after high-speed rotation by the centrifugal dehydrator, the water is preliminarily dewatered, the produced water is flocculated and precipitated in the sedimentation clean water pool, and the treated clean water is pumped back into the first washing pool, the second washing pool and the third washing pool to supplement water; the sludge produced after centrifugal dewatering is further dewatered and dried by the sludge plate and frame filter press;

[0032] (3) Cracking process: after the plastic is washed, it is packaged and transported to the stockyard for temporary storage, and the contained moisture is naturally dried; after drying, the material is sent into the feeding conveyor by the loader, the material is fed into the cracking device through the feeding conveyor, and the material is cracked into high-temperature oil gas and carbon powder in the cracking device; the high-temperature oil gas enters the oil gas separation mechanism, and the cracking gas and the cracking oil are separated; the cracking gas is sent into the hot blast furnace as fuel, the high-temperature flue gas generated is used as a heat source to heat the cracking device, the cracking oil is sent into the oil tank for temporary storage and sold, and the carbon powder is packaged by the carbon powder packaging machine and then transported out.

[0033] After the preparation work of the landfill site of household garbage, such as pile shaping, odor control and pile dewatering, the excavation system starts to excavate, and after excavation, it is dried, and then the material is fed to the screening system when the water content in the garbage meets the requirements of the screening equipment.

[0034] Compared with the prior art, the present application has the following advantages and effects:

[0035] 1. The present application reasonably utilizes the plastic materials in the landfill site, and increases the economic value of the reutilization.

[0036] 2. The present application reduces the transportation cost, treatment cost and secondary pollution caused by burning of plastic materials.

[0037] 3. The present application reduces the carbon emission caused by burning of plastic materials.

[0038] 4. The present application produces cracking oil, carbon powder and cracking gas after the excavation, screening and water washing of the landfill site of household garbage, the cracking oil can be refined to non-standard gasoline and diesel oil, or deeply processed to high-quality chemical raw materials of ethylene and propylene, the carbon powder has high calorific value and can be used in cement kiln or made into fuel, and the cracking gas can be used as alternative fuel for energy supply; all of them have high secondary utilization value, and the selling cost can be used to offset the cost of excavation and screening. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The present application is a structural schematic diagram of an embodiment. DETAILED DESCRIPTION

[0040] The present application will be further described in detail below in combination with the drawings and by embodiments, and the following embodiments are an explanation of the present application but the present application is not limited to the following embodiments.

[0041] The present application includes an excavation system A, a screening system B, a water washing system C and a cracking system D.

[0042] The excavation system A includes a garbage excavator A1, a loading vehicle A2, a drying and temporary storage greenhouse A3 and a forklift A4.

[0043] The screening system B includes a uniform material conveyor B1, a first-stage roller screen B2, a plastic separator B3, a screen overs conveyor B4, a plastic conveyor B5, a screen overs magnetic separator B6, an air separator B7, a screen unders conveyor B8, a screen unders magnetic separator B9, a second-stage roller screen B10, a ferrous metal buffer bin B11, a ferromagnetic metal collection conveyor B12, a humus soil buffer bin B13, a humus soil conveyor B14, an aggregate collection conveyor B15, an aggregate buffer bin B16, a light material collection conveyor B17, and a light material buffer bin B18.

[0044] The water washing system C includes a first washing pool C1, a first salvaging machine C2, a crusher C3, a second washing pool C4, a second salvaging machine C5, a strong washing machine C6, a third washing pool C7, a plastic packing machine C8, a chemical feeding room C9, a sediment clean water pool C10, a sewage pool C11, a centrifugal dehydrator C12, and a sludge plate-and-frame filter press C13.

[0045] The pyrolysis system D includes a stockyard D1, a loader D2, a feeding conveyor D3, a pyrolysis device D4, a hot blast stove D5, an oil-gas separation mechanism, an oil tank D8, a carbon powder discharge screw conveyor D9, a carbon powder packing machine D10, and a flue gas purification device D11. The oil-gas separation mechanism includes a first oil-gas separator D6 and a second oil-gas separator D7.

[0046] The waste excavator A1 cooperates with the loading vehicle A2, the loading vehicle A2 cooperates with the airing and temporary storage greenhouse A3, and the forklift A4 cooperates with the airing and temporary storage greenhouse A3.

[0047] The forklift A4 cooperates with the uniform material conveyor B1, the uniform material conveyor B1 is connected with the inlet of the first-stage roller screen B2; the screen overs outlet of the first-stage roller screen B2 is connected with the inlet of the plastic separator B3, the light material outlet of the plastic separator B3 is connected with the inlet of the first washing pool C1 through the plastic conveyor B5; the screen unders outlet of the first-stage roller screen B2 is connected with the inlet of the second-stage roller screen B10 through the screen unders conveyor B8; the screen unders outlet of the second-stage roller screen B10 is connected with the humus soil buffer bin B13 through the humus soil conveyor B14; the screen overs outlet of the second-stage roller screen B10 is connected with the aggregate buffer bin B16 through the aggregate collection conveyor B15; the heavy material outlet of the plastic separator B3 is connected with the inlet of the air separator B7 through the screen overs conveyor B4; the heavy material outlet of the air separator B7 is connected with the aggregate buffer bin B16 through the aggregate collection conveyor B15; the light material outlet of the air separator B7 is connected with the light material buffer bin B18 through the light material collection conveyor B17; the screen overs magnetic separator B6 is arranged above the screen overs conveyor B4, the screen unders magnetic separator B9 is arranged above the screen unders conveyor B8, and the screen overs magnetic separator B6 and the screen unders magnetic separator B9 are connected with the ferrous metal buffer bin B11 through the ferromagnetic metal collection conveyor B12.

[0048] The first cleaning pool C1 is connected with the first salvaging machine C2; the first salvaging machine C2 is connected with the inlet of the crusher C3; the outlet of the crusher C3 is connected with the second cleaning pool C4; the second cleaning pool C4 is connected with the second salvaging machine C5; the second salvaging machine C5 is connected with the inlet of the strong washing machine C6; the outlet of the strong washing machine C6 is connected with the third cleaning pool C7; the third cleaning pool C7 is connected with the plastic packing machine C8.

[0049] The bottom of the first cleaning pool C1, the second cleaning pool C4 and the third cleaning pool C7 is provided with a residue discharging device; the residue is discharged and backfilled to the landfill site.

[0050] The first cleaning pool C1, the second cleaning pool C4 and the third cleaning pool C7 are provided with a cleaning water outlet and a water supplementing port; the cleaning water outlet of the first cleaning pool C1, the second cleaning pool C4 and the third cleaning pool C7 is connected with the inlet of the sewage pool C11; the outlet of the sewage pool C11 is connected with the inlet of the centrifugal dehydrator C12; the water outlet of the centrifugal dehydrator C12 is connected with the inlet of the sediment clear water pool C10; the outlet of the sediment clear water pool C10 is connected with the water supplementing port of the first cleaning pool C1, the second cleaning pool C4 and the third cleaning pool C7; the dosing room C9 is connected with the sediment clear water pool C10; the sludge outlet of the centrifugal dehydrator C12 is connected with the inlet of the sludge plate-frame filter press C13; the water outlet of the sludge plate-frame filter press C13 is connected with the inlet of the sediment clear water pool C10.

[0051] The plastic packing machine C8 is matched with the stockyard D1; the loading vehicle D2 is matched with the stockyard D1 and the feeding conveyor D3; the feeding conveyor D3 is connected with the inlet of the cracking device D4; the oil gas outlet of the cracking device D4 is connected with the inlet of the first oil gas separator D6 of the oil gas separation mechanism; the outlet of the first oil gas separator D6 is connected with the inlet of the second oil gas separator D7; the carbon powder outlet of the cracking device D4 is connected with the carbon powder packing machine D10 through the carbon powder discharging screw D9; the cracking oil outlet of the second oil gas separator D7 is connected with the oil tank D8; the cracking gas outlets of the first oil gas separator D6 and the second oil gas separator D7 are connected with the fuel inlet of the hot blast furnace D5; the flue gas outlet of the hot blast furnace D5 is connected with the cracking device D4; the flue gas outlet of the cracking device D4 is connected with the flue gas purification device D11.

[0052] The size and position of the excavation system A, the screening system B, the water washing system C and the cracking system D can be adjusted according to the actual situation.

[0053] The screening system B, the water washing system C and the cracking system D are arranged in the workshop; the deodorization device E is arranged in the workshop to treat the odor in the system and discharge after reaching the standard.

[0054] The various conveyors can adopt belt conveyors.

[0055] A working method of a domestic waste landfill excavation, screening and water washing and cracking system, comprising the following steps:

[0056] (1) Overall steps: excavation process → screening process → water washing process → cracking process.

[0057] (2) Excavation process: after the preparation work of landfill pile shaping, odor control, pile dewatering and the like is completed, the waste excavator A1 starts the excavation work, and after the excavation, the loader A2 is used to transport the waste to the airing and temporary storage greenhouse A3, and after the water content in the waste meets the requirement of the screening equipment, the forklift A4 is used to feed the waste to the screening system.

[0058] (3) Screening process: the waste of the domestic waste landfill excavation system is fed to the uniform material conveyor B1 by the forklift A4, the uniform material conveyor B1 can uniformly feed the material to ensure the stable input of the material of the system. The screening system finally screens out five categories of plastic, humus, aggregate, light material and iron metal. The screening process specifically comprises the following steps:

[0059] (3-1) Plastic: the uniform material conveyor B1 feeds the material to the first-stage roller screen B2, the screen hole of the roller screen is generally 60-100 mm, and the material larger than 60-100 mm is fed to the plastic separator B3, and the conveyor is arranged below the plastic separator B3, and the flexible material remover similar to the circular comb is arranged above the conveyor in parallel to the conveying direction. The plastic, cloth strips and bamboo pieces and other light materials are removed by the flexible material remover during the transportation above the belt, and are sent to the water washing system by the plastic conveyor B5;

[0060] (3-2) Humus: the undersize material of the first-stage roller screen B2 generally contains humus and aggregate with small particle size, and can be fed to the second-stage roller screen B10 through the undersize belt B8, the screen hole of the roller screen is generally 20-40 mm, and the undersize material smaller than the screen hole is fed to the humus buffer bin B13 through the humus conveyor B14 and then is transported out;

[0061] (3-3) Aggregate: the first-stage roller screen B2 and the second-stage roller screen B10 both produce aggregate. The undersize material of the first-stage roller screen B2 generally contains humus and aggregate with small particle size, and can be fed to the second-stage roller screen B10 through the undersize belt B8, the screen hole of the roller screen is generally 20-40 mm, and the oversize material larger than the screen hole is fed to the aggregate buffer bin B16 through the aggregate collecting conveyor B15 and then is transported out of the factory; in addition, the heavy material in the plastic separator B3 and other materials with small volume which are not separated by the light screening are fed to the air separator B7 through the oversize conveyor B4, the light material is blown out through the air separator B7, and the remaining heavy material (generally stone aggregate) is fed to the aggregate buffer bin B16 through the aggregate collecting conveyor B15 and then is transported out of the factory.

[0062] (3-4)Light material: the material on the screen after the first cylinder screen B2 enters the plastic separator B3, and the heavy material and other materials in the plastic separator B3 that are not separated by the light screen enter the air separator B7 through the screen material conveyor B4, and the light material is blown out of the air separator B7 and then enters the light material buffer bin B18 through the light material collection conveyor B17 and is transported out of the factory.

[0063] (3-5)Iron metal: the screen material conveyor B4 and the screen under material conveyor B8 are provided with a screen material magnetic separator B6 and a screen under material magnetic separator B9, respectively, and the metal after magnetic separation enters the iron metal buffer bin B11 through the ferromagnetic metal collection conveyor B12 and is transported out of the factory.

[0064] (4) Water washing process: the light material such as plastic, cloth and bamboo in the screening system is sent to the first cleaning tank C1 through the plastic conveyor B5, three stirring wheels are arranged above the cleaning tank to stir the water in the tank forward, and a slag discharge mechanism is arranged at the bottom to collect and discharge the impurities after cleaning. The first cleaning tank C1 mainly functions to preliminarily clean the light material such as plastic, cloth and bamboo, among which the plastic and bamboo will float, the plastic is fished out by the first fishing machine C2 (a plurality of metal rods with a length of about 10 cm are arranged at intervals of about 10 cm above the fishing machine, which can pick up the plastic, while the bamboo will fall into the gap between the metal rods), the sand and other substances in the other plastic will sink to the bottom of the tank and be discharged outside through the slag discharge mechanism in the cleaning tank. The plastic fished out by the first fishing machine C2 enters the crusher C3 for crushing, enters the second cleaning tank C4, which functions to further clean the small amount of sand and other impurities in the crushed plastic, and then the plastic is fished out by the second fishing machine C5 and enters the strong washing machine C6, which basically cleans the plastic through the internal high-pressure water flow, and then the plastic after the last cleaning enters the plastic packaging machine C8, which is provided with a compressor to compress and remove the excess water and then package and transport out, and the compressed water is collected and recycled.

[0065] The water in the cleaning tank is replaced daily, and the water after cleaning the first cleaning tank C1, the second cleaning tank C4 and the third cleaning tank C7 is pumped into the sewage tank C11, and then is preliminarily dewatered by the centrifugal dewatering machine C12 after high-speed rotation, the generated water enters the sedimentation clean water tank C10 and is flocculated and precipitated by the dosing interval C9, and the treated clean water is pumped back into the cleaning tank for water replenishment; and the sludge generated after centrifugal dewatering is further dewatered and dried by the sludge plate and frame filter press C13, and the mud cake is backfilled in place. The water used for starting the whole system is about 300 tons, all the water is recycled, about 30 tons of clean water is supplemented daily, and the main water loss is natural evaporation, plastic packaging, bottom slag and mud cake.

[0066] (5) Cracking process: After plastic water washing, it is packed and transported to the stockyard D1 for temporary storage, and the contained moisture is naturally air-dried. After air-drying, the material is sent to the feeding conveyor D3 by the loader D2, and the material is uniformly fed to the cracking device D4 through the feeding conveyor D3. The material is fully heat exchanged with high-temperature flue gas in the cracking device D4, and is cracked into high-temperature oil gas and carbon powder. The high-temperature oil gas enters the first oil gas separator D6 and the second oil gas separator D7 in turn for cooling, and the cracking gas and cracking oil are separated out. The working principle of the oil gas separator is to cool the high-temperature oil gas by using a cooling medium (such as cooling water). At the same time of rapid cooling of the oil gas, the heavy component substances (such as C5-C10 alkanes) are cooled to become cracking oil, and the light component substances (such as H2, CH4, etc.) cannot be condensed and are discharged as cracking gas. The cracking gas can be sent to the hot blast furnace D5 as fuel for combustion, and the high-temperature flue gas generated is used as a heat source for the cracking device D4. After fully indirect heat exchange in the cracking device D4, the high-temperature flue gas becomes low-temperature waste flue gas, which is sent to the flue gas purification device D11 for treatment and then discharged in accordance with the standard. If there is abundant non-condensable gas, it can be sent to a flare, a boiler or other gas utilization system for collaborative utilization. The cracking oil is sent to the oil tank D8 for temporary storage and then sold. The carbon powder is packed by the carbon powder packing machine D10 and then shipped out.

[0067] According to the investigation of many landfill sites in China, the average proportion of plastics is about 20%. According to the pilot test of a certain project, cracking produces cracking oil, carbon powder and cracking gas, with a proportion of about 45:35:20. According to the investigation, the selling price of cracking oil is about 4000 yuan / ton, the benefit generated by cracking gas according to the heat value is about 2000 yuan / ton, and the selling price of carbon powder is about 1000 yuan / ton. According to this calculation, considering the conventional excavation process (disposal of various screened materials after excavation and screening, about 200 yuan / m³), water washing, cracking device, civil engineering cost, operation cost and other conditions, under the condition that the stockpile of the landfill site is 150,000 cubic meters, the increased water washing and cracking income can cover the cost. When the stockpile of the landfill site is more than 960,000 cubic meters, the generated income can cover all the treatment costs of the landfill site. The larger the stockpile, the higher the proportion of treatment costs that can be covered.

[0068] In addition, it should be noted that the specific embodiments described in the specification, the shape of the parts, the name taken, etc. can be different, and the above described in the specification is only an example of the structure of the present application. Any equivalent changes or simple changes made in accordance with the structure, features and principles described in the patent concept of the present application are included in the protection scope of the present application. Those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, as long as they do not deviate from the structure of the present application or exceed the scope defined by the present claims, which should belong to the protection scope of the present application.

Claims

1. A municipal solid waste landfill excavation, screening, water washing and pyrolysis system, characterized by: The excavation system, the screening system, the water washing system and the cracking system; the screening system comprises a uniform material conveyor, a first-stage roller screen, a plastic separator, an oversize conveyor, a plastic conveyor, an oversize magnetic separator, an air separator, an undersize conveyor, an undersize magnetic separator, a second-stage roller screen, an iron metal buffer bin, a ferromagnetic metal collection conveyor, a humus soil buffer bin, a humus soil conveyor, an aggregate collection conveyor, an aggregate buffer bin, a light material collection conveyor and a light material buffer bin; the water washing system comprises a first cleaning tank, a first material salvaging machine, a crusher, a second cleaning tank, a second material salvaging machine, a strong washing machine, a third cleaning tank, a plastic packing machine, a clean water sedimentation tank, a sewage tank, a centrifugal dehydrator and a sludge plate-and-frame filter press; the cracking system comprises a stockyard, a loader, a feeding conveyor, a cracking device, a hot blast furnace, an oil-gas separation mechanism, an oil tank and a carbon powder packing machine; The excavation system cooperates with the uniform material conveyor; the uniform material conveyor is connected with the inlet of the first-stage roller screen; the oversize outlet of the first-stage roller screen is connected with the inlet of the plastic separator, and the light material outlet of the plastic separator is connected with the first cleaning tank through the plastic conveyor; the undersize outlet of the first-stage roller screen is connected with the inlet of the second-stage roller screen through the undersize belt; the undersize outlet of the second-stage roller screen is connected with the humus soil buffer bin through the humus soil conveyor; the oversize outlet of the second-stage roller screen is connected with the aggregate buffer bin through the aggregate collection conveyor; the heavy material outlet of the plastic separator is connected with the inlet of the air separator through the oversize conveyor; the heavy material outlet of the air separator is connected with the aggregate buffer bin through the aggregate collection conveyor; the light material outlet of the air separator is connected with the light material buffer bin through the light material collection conveyor; the oversize magnetic separator is arranged on the oversize conveyor, and the undersize magnetic separator is arranged on the undersize conveyor; the oversize magnetic separator and the undersize magnetic separator are connected with the iron metal buffer bin through the ferromagnetic metal collection conveyor; the first cleaning tank is connected with the first material salvaging machine; the first material salvaging machine is connected with the inlet of the crusher, and the outlet of the crusher is connected with the second cleaning tank; the second cleaning tank is connected with the second material salvaging machine; the second material salvaging machine is connected with the inlet of the strong washing machine; the outlet of the strong washing machine is connected with the third cleaning tank; the third cleaning tank is connected with the plastic packing machine; the first cleaning tank, the second cleaning tank and the third cleaning tank are all provided with a cleaning water outlet and a water supplementing port; the cleaning water outlets of the first cleaning tank, the second cleaning tank and the third cleaning tank are connected with the inlet of the sewage tank; the outlet of the sewage tank is connected with the inlet of the centrifugal dehydrator; the water outlet of the centrifugal dehydrator is connected with the inlet of the clean water sedimentation tank; the outlet of the clean water sedimentation tank is connected with the water supplementing ports of the first cleaning tank, the second cleaning tank and the third cleaning tank; the sludge outlet of the centrifugal dehydrator is connected with the inlet of the sludge plate-and-frame filter press; The plastic packing machine is matched with the stockyard; the loading vehicle is matched with the stockyard and the feeding conveyor; the feeding conveyor is connected with the inlet of the cracking device; the oil gas outlet of the cracking device is connected with the inlet of the oil gas separation mechanism; the carbon powder outlet of the cracking device is connected with the carbon powder packing machine; the cracking oil outlet of the oil gas separation mechanism is connected with the oil tank; the cracking gas outlet of the oil gas separation mechanism is connected with the fuel inlet of the hot blast furnace; the flue gas outlet of the hot blast furnace is connected with the cracking device; The cracking system further comprises a flue gas purification device connected with the cracking device.

2. The MSW landfill excavation, screening, water washing and pyrolization system according to claim 1, characterized in that: The excavation system comprises a garbage excavator, a loading vehicle, a drying and temporary storage greenhouse and a forklift; the garbage excavator is matched with the loading vehicle; the loading vehicle is matched with the drying and temporary storage greenhouse; the forklift is matched with the drying and temporary storage greenhouse; the forklift is matched with the uniform material conveyor.

3. The MSW landfill excavation, screening, water washing and pyrolization system according to claim 1, characterized in that: The bottom of the first cleaning pool, the second cleaning pool and the third cleaning pool is provided with a residue discharge device.

4. The MSW landfill excavation, screening, water washing and size reduction system according to claim 1, wherein: The water washing system further comprises a dosing room connected with the sedimentation clean water pool.

5. The MSW landfill excavation, screening, water washing and pyrolization system according to claim 1, wherein: The water outlet of the sludge plate-and-frame filter press is connected with the inlet of the sedimentation clean water pool.

6. The MSW landfill excavation, screening, water washing and pyrolization system according to claim 1, characterized in that: The oil gas separation mechanism comprises a first oil gas separator and a second oil gas separator; the oil gas outlet of the cracking device is connected with the inlet of the first oil gas separator; the outlet of the first oil gas separator is connected with the inlet of the second oil gas separator; the cracking oil outlet of the second oil gas separator is connected with the oil tank; the cracking gas outlets of the first oil gas separator and the second oil gas separator are connected with the fuel inlet of the hot blast furnace.

7. The MSW landfill excavation, screening, water washing and pyrolization system according to claim 1, characterized in that: The carbon powder outlet of the cracking device is connected with the carbon powder packing machine through a carbon powder discharge screw conveyor.

8. A method of operating a waste landfill excavation, screening, water washing and size reduction system as claimed in any one of claims 1 to 7, characterised by: The method comprises the following steps: (1) screening process: the garbage excavated by the excavation system in the domestic garbage landfill is fed to the uniform material conveyor, and five categories of plastic, humus, aggregate, light material and iron metal are finally screened out by the screening system; the screening process comprises the following steps: (1-1) plastic: the uniform material conveyor is fed into the first-stage roller screen, the screened material is fed into the plastic separator, and the separated plastic is sent to the water washing system through the plastic conveyor; (1-2) humus: the undersize material of the first-stage roller screen is fed into the second-stage roller screen through the undersize material belt, and the undersize material of the second-stage roller screen is fed into the humus buffer bin through the humus conveyor; (1-3) aggregate: the oversize material of the second-stage roller screen is fed into the aggregate buffer bin through the aggregate collection conveyor; the heavy material separated in the plastic separator is fed into the winnowing machine through the oversize material conveyor, and the heavy material after winnowing is fed into the aggregate buffer bin through the aggregate collection conveyor; (1-4) light material: the light material after winnowing of the winnowing machine is fed into the light material buffer bin through the light material collection conveyor; (1-5) iron metal: the metal after magnetic separation of the oversize material magnetic separator and the undersize material magnetic separator is fed into the iron metal buffer bin through the ferromagnetic metal collection conveyor; (2) Water washing process: the plastics in the screening system are sent into a first washing tank by a plastic conveyor, the plastics in the first washing tank are fished out by a first fishing machine and sent into a crusher, then after crushing, the plastics are sent into a second washing tank, the plastics in the second washing tank are fished out by a second fishing machine and sent into a strong washing machine, after being washed clean, the plastics are sent into a third washing tank, and after the last washing, the plastics are sent into a plastic packing machine; After washing the first, second and third washing tanks, water is sprayed into a sewage tank, and after high-speed rotation by a centrifugal dewatering machine, the plastics are preliminarily dewatered, the generated water is sent into a sedimentation clean water tank for flocculation and sedimentation, the treated clean water is sprayed back into the first, second and third washing tanks for water replenishment, and the sludge generated after centrifugal dewatering is further dewatered and dried by a sludge plate and frame filter press; (3) Cracking process: after the plastics are washed and packed, they are transported to a stockyard for temporary storage, and the contained water is naturally dried; after drying, the materials are sent into a feeding conveyor by a loader, the materials are fed into a cracking device by the feeding conveyor, and the materials are cracked into high-temperature oil gas and carbon powder in the cracking device; The high-temperature oil gas enters an oil gas separation mechanism, and cracking gas and cracking oil are separated out; The cracking gas is sent into a hot blast furnace as fuel, the generated high-temperature flue gas is used as a heat source to heat the cracking device, the cracking oil is sent into an oil tank for temporary storage and external sale, and the carbon powder is packed by a carbon powder packing machine and then shipped out.

9. The method of claim 8, wherein the method further comprises: After the preparation work of the landfill site, such as pile shaping, odor control and pile dewatering, the excavation system starts the excavation work, and after excavation, the materials are dried, and then the materials are fed into the screening system when the water content in the materials meets the requirements of the screening equipment.

Images