White waste pollutant pyrolysis gasification multi-quality grading efficient utilization device and method

Abstract

The application provides a white waste pollutant cracking gasification multi-quality grading efficient utilization device and method, and the device comprises: a closed pretreatment unit, a low-temperature pre-dechlorination melting unit, a segmented gradient cracking gasification double-reactor unit, a multi-stage multi-quality grading separation unit, a waste heat recycling energy supply unit, a product refining and storage unit and a residue resource modification unit which are sequentially arranged; the segmented gradient cracking gasification is divided into a low-temperature pyrolysis section, a medium-temperature catalytic gasification section and a high-temperature reforming and coke removal section, and is matched with gas-solid countercurrent contact and stepwise temperature field regulation to realize step-by-step chain breaking of plastic macromolecules; the multi-stage multi-quality grading separation synchronously separates five types of products, i.e., light olefin gas, medium fuel oil, heavy waxy substance, gasification semi-coke and inorganic ash, and each product is independently refined and recovered.

Description

Technical Field

[0001] This application relates to the field of waste treatment technology, and in particular to a device and method for the efficient utilization of white waste pollutants through pyrolysis, gasification, and grading. Background Technology

[0002] White waste pollutants are mainly composed of polyethylene, polypropylene, polystyrene, PVC, and PET plastics, with an annual output exceeding tens of millions of tons. Traditional disposal methods are divided into three categories: landfill, incineration, and simple pyrolysis, all of which have significant shortcomings. 1. Landfill: Plastics have a degradation cycle of over 100 years, occupy land, and leachate contains plasticizers and heavy metals that pollute the soil and groundwater; 2. Direct incineration: The flue gas contains a large amount of HCl and dioxins, and the cost of supporting tail gas treatment is high. It only recovers heat and cannot recover high-value chemical raw materials, resulting in serious waste of carbon resources. 3. Traditional single-stage pyrolysis unit: Only a single cracking furnace is set up. Chlorinated plastics are not dechlorinated in advance, and HCl corrodes the furnace tubes and poisons the catalyst at high temperatures. The raw materials are mixed without graded pretreatment, and mud, sand and metal impurities enter the furnace body, causing slagging and wear. Pyrolysis, gasification and reforming are carried out simultaneously in the same temperature zone, and the products are mixed and cannot be separated. Light olefins, fuel oil and waxes are miscible, and the separation and purification cost is extremely high. The tar yield is 15% to 28%, which easily clogs the pipeline and reduces the oil and gas yield. Solid slag is simply discharged externally, and semi-coke and ash are not recycled. The system heat matching is unbalanced, the external heating energy consumption is high, and the carbon comprehensive recovery rate is less than 70%.

[0003] Existing technologies for treating white waste pollutants mostly focus on single-material pyrolysis of plastics, single-stage gasification, and single-product oil recovery. They lack integrated systems for pre-dechlorination, three-stage gradient pyrolysis and gasification, three-stage graded separation, and full solid slag resource utilization of mixed-color white waste plastics in urban and rural areas. They cannot simultaneously achieve high-value utilization of five types of products: gas, light oil, heavy wax, semi-coke, and inorganic ash residue. They also suffer from common industry pain points such as difficulty in removing tar, chlorine corrosion, mixed products, high energy consumption, and unusable by-products. Summary of the Invention

[0004] This application provides a device and method for efficient utilization of white waste pollutants through pyrolysis, gasification, and grading, in order to at least address the shortcomings of the aforementioned related technologies.

[0005] In a first aspect, embodiments of this application provide a highly efficient utilization device for white waste pollutants through pyrolysis, gasification, and grading, comprising: A closed pretreatment unit is used for crushing white waste pollutants, air separation to remove impurities, water washing to remove mud, extrusion to dewater, and magnetic separation to remove metals. The low-temperature pre-dechlorination melting unit has its feed end connected to the discharge port of the sealed pretreatment unit, and its interior is equipped with an alkaline calcium-based dechlorination agent static mixing component, a jacketed low-temperature heating chamber, a melting filter screen plate, and a chlorine-containing waste gas adsorption branch. The segmented gradient pyrolysis gasification dual-reactor unit includes a downflow low-temperature pyrolysis reactor and a countercurrent fluidized bed high-temperature gasification reforming reactor. The top of the low-temperature pyrolysis reactor is connected to the molten liquid outlet of the low-temperature pre-dechlorination melting unit, and the bottom gas-solid mixing outlet is connected to the middle of the countercurrent fluidized bed high-temperature gasification reforming reactor. The low-temperature pyrolysis reactor is equipped with a 320-420℃ constant-temperature pyrolysis chamber, and the countercurrent fluidized bed is equipped with a 450-600℃ catalytic gasification zone and a 700-850℃ high-temperature reforming decoking zone. The bottom of the countercurrent fluidized bed is equipped with a steam / oxygen-enriched gas distribution assembly, and the top is equipped with a high-temperature oil and gas total outlet. The multi-stage fractional separation unit has its inlet end connected to the high-temperature oil and gas outlet of the segmented gradient cracking and gasification dual reactor unit. It is connected in series with a first-stage quenching light gas separation tower, a second-stage medium oil distillation tower, and a third-stage heavy wax settling separation tank. It is equipped with a three-stage independent condensation heat exchange branch, a gas-liquid separator, and a tar deep catalytic cracking sub-line. The waste heat circulation energy supply unit is connected to the jacket of the low-temperature pre-dechlorination melting unit, the heat exchange chamber of the segmented gradient pyrolysis gasification dual reactor, and the reboiler of the multi-stage fractionation and separation unit, and includes a flue gas waste heat boiler, an oil and gas waste heat exchanger, a circulating heat transfer oil circuit, and a gasification low-calorific-value gas combustion supplementary heating branch. The product refining and storage unit includes an olefin gas refining tank connected to the product outlet of the primary quench light gas separator, an industrial fuel oil storage tank connected to the product outlet of the secondary medium oil distillation tower, and a plastic wax raw material storage tank connected to the product outlet of the tertiary heavy wax settling separator. The residue resource utilization modification unit has its feed end connected to the slag discharge port of the countercurrent fluidized bed and the inorganic filter residue outlet of the low-temperature pre-dechlorination melting unit. The residue resource utilization modification unit includes a semi-coke grinding and modification component, an ash neutralization and compounding bin, and a finished product matrix discharge port.

[0006] Furthermore, the sealed pretreatment unit includes a sealed crusher, a negative pressure air separation chamber, a counter-current water washing screw conveyor, a twin-screw extrusion dewatering machine, and a permanent magnet drum magnetic separator. The sealed pretreatment unit maintains a slight negative pressure of -50 to -150 Pa and is equipped with an activated carbon adsorption deodorization branch for exhaust gas.

[0007] Furthermore, the internal alkaline calcium-based dechlorinating agent of the low-temperature pre-dechlorination melting unit is a compound powder of calcium carbonate, calcium hydroxide, and blast furnace steel slag fine powder in a mass ratio of 3:2:1. The melting heating temperature is controlled at 190-260℃, and the pore size of the melting filter screen plate is 0.8-1.5mm. The filtered inorganic impurities are directly sent to the residue resource utilization modification unit. During the melting process, the HCl gas precipitated is passed into the alkaline spray adsorption branch to generate calcium chloride solid slag for simultaneous recovery.

[0008] Furthermore, the interior of the downward-flowing low-temperature pyrolysis reactor is equipped with multi-layer atomizing nozzles, and the atomized particle size of the molten plastic liquid is controlled at 20-80μm. A rotating gas-solid separation grid is installed at the bottom of the low-temperature pyrolysis reactor, and the primary oil and gas generated by pyrolysis are fed downward into the countercurrent fluidized bed. The incompletely pyrolyzed heavy liquid phase is returned to the low-temperature pyrolysis reactor for recycling and pyrolysis.

[0009] Furthermore, the high-temperature gasification reforming reactor in the countercurrent fluidized bed contains nickel-modified dolomite catalyst particles, which slowly fall from top to bottom while the oil and gas come into countercurrent contact from bottom to top. The gasifying agent is a mixture of steam and low-concentration oxygen-enriched gas, with the steam injection rate being 8% to 15% of the mass of the molten plastic raw material and the oxygen volume fraction being 25% to 35%. The high-temperature reforming decoking zone is filled with a honeycomb ceramic carrier reforming catalyst, which completely decomposes the residual tar into small-molecule syngas.

[0010] Furthermore, the multi-stage fractionation and separation unit adopts a stepped cooling and fractionation mechanism: the first-stage rapid cooling light gas separator is cooled to 30-50°C to separate C1-C4 light olefin fuel gas; the second-stage medium oil distillation tower has a top temperature of 180-230°C to separate C5-C22 industrial fuel oil; the third-stage heavy wax settling separator has a temperature of 60-100°C to retain high-melting-point plastic wax of C23 and above; the trace heavy tar produced by the third-stage separation of the multi-stage fractionation and separation unit is returned to the high-temperature reforming decoking zone for secondary cracking.

[0011] Furthermore, the waste heat recycling unit recovers heat from high-temperature oil and gas and reactor flue gas, and the heat transfer oil circulation loop supplies heat to the low-temperature pre-dechlorination melting unit and the distillation tower reboiler, respectively. The self-produced low-calorific-value olefin gas is used as supplementary heating fuel, and the external heat input is 0 under normal operating conditions.

[0012] Secondly, the present invention also proposes a method for efficient utilization of white waste pollutants through pyrolysis, gasification, and classification, applied to the aforementioned efficient utilization device for white waste pollutants through pyrolysis, gasification, and classification, comprising the following steps: Step 1: Closed pretreatment for impurity removal and sorting: The mixed white waste pollutants are fed into a closed crusher to be crushed to a particle size of 20-50mm. Negative pressure air separation separates light impurities from paper and fabric. Countercurrent water washing removes mud, sand, and food residue. Twin screw extrusion dewaters the material to a moisture content of ≤3%. Permanent magnet drum removes metal impurities such as iron wire and aluminum foil. The purified pure plastic material is then sent to a low-temperature pre-dechlorination melting unit. Step 2: Low-temperature melting and simultaneous pre-dechlorination: The pure plastic is fed into a jacketed melting chamber at 190-260°C and thoroughly mixed with a calcium-based dechlorinating agent. The plastic is completely melted and liquefied, and PVC and chlorine-containing plastic products decompose and release HCl. The HCl is converted into solid calcium chloride and recovered by alkaline spraying. The molten liquid is filtered through a sieve plate to remove inorganic impurities such as sand and glass. The molten plastic liquid is then sent to a downflow low-temperature pyrolysis reactor by a high-pressure atomizing pump. Step 3: Three-stage gradient pyrolysis and reforming: Low-temperature pyrolysis section: The molten plastic liquid is atomized and enters the downward pyrolysis reactor at 320-420℃, where the macromolecular plastic undergoes initial chain scission to generate primary oil and gas and a small amount of heavy liquid droplets; Medium-temperature catalytic gasification section: The primary oil and gas enter the 450-600℃ catalytic zone of the countercurrent fluidized bed, and water vapor-oxygen-enriched gasifying agent is introduced. The heavy components are catalytically gasified to generate small molecule hydrocarbons, H2, CO syngas; High-temperature reforming and decoking section: The mixed oil and gas rise into the 700-850℃ reforming zone, where residual tar and carbon deposits are completely cracked, eliminating tar blockage problems; Step 4: Multi-stage fractional condensation and separation: High-temperature oil and gas sequentially enter a three-stage fractional separation unit, and the products are separated by step cooling: the first stage is rapid quenching to separate light olefin fuel gas, the second stage is distillation to separate medium-quality industrial fuel oil, and the third stage is sedimentation to separate heavy plastic wax; the trace amount of unpyrolyzed tar is recycled back to the high-temperature reforming zone for further processing. Step 5: Waste heat cascade recycling: High-temperature flue gas and high-temperature oil gas from the reactor are heated by a waste heat boiler and heat exchanger to heat the heat transfer oil, which is then supplied as a heat source to the melting unit and distillation column; the low-calorific-value olefin fuel gas obtained from the separation is burned to supplement the system's heat, achieving heat self-sufficiency; Step Six: Refining and Storage of Liquid and Gas Phase Products: Light olefin gas is stored after desulfurization and dehydration for use in chemical synthesis and gas-fired power generation; medium fuel oil is refined after decolorization and impurity removal for use as industrial boiler fuel; heavy plastic wax is filtered and refined for use as a plastic modifying agent and raw material for waterproof wax. Step 7: Resource-based modification and utilization of solid slag: The carbon-rich semi-coke discharged from the fluidized bed is ground and activated to make adsorption packing; the inorganic ash slag and calcium chloride by-products generated by melt filtration are mixed and neutralized, and compounded with organic matter to make soil remediation and improvement matrix. All solid slag is resource-based, and no hazardous waste is directly landfilled.

[0013] Furthermore, in step three, the recycling process for the nickel-based modified dolomite catalyst is as follows: The deactivated catalyst at the bottom of the fluidized bed is periodically discharged and sent to an air regeneration furnace at 720-780℃ to burn off the surface carbon. After regeneration, it is recycled back to the countercurrent fluidized bed catalytic gasification zone. The catalyst has a single cycle life of ≥120h.

[0014] Furthermore, the method maintains a closed operation with a slight negative pressure of -30 to -180 Pa throughout the process. All waste gas and volatile matter are uniformly collected into the activated carbon adsorption and catalytic combustion tail gas treatment device. The tail gas is discharged after meeting the standards, with no odor and no fugitive escape of organic waste gas.

[0015] Compared with related technologies, the efficient utilization device and method for pyrolysis, gasification, and classification of white waste pollutants provided in this application has the following advantages: 1. Mix chlorine-containing white plastics and perform low-temperature dechlorination in advance to avoid high-temperature HCl corrosion of the reactor and catalyst poisoning; 2. Three-stage gradient temperature pyrolysis and gasification, with step-by-step chain breaking + catalytic gasification + high-temperature reforming, completely converts tar and significantly improves the yield of small molecule products. 3. Multi-stage cooling and fractional separation simultaneously extracts three types of liquid and gaseous products: olefin gas, fuel oil, and plastic wax, eliminating the need for complex secondary distillation. 4. Waste heat is fully recovered in stages + self-generated natural gas is used for supplemental heating, so that the system is self-sufficient in heat and reduces production energy consumption and carbon emissions; 5. The solid slag is modified and utilized in two categories: semi-coke is used to make adsorbent materials and inorganic ash is used to make soil conditioners, with no waste solid slag produced. 6. The entire process is a closed-loop system with slight negative pressure, which suppresses the fugitive emission of organic waste gas and ensures that the exhaust gas meets the standards.

[0016] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a structural block diagram of the white waste pollutant pyrolysis gasification and graded high-efficiency utilization device in the first embodiment of the present invention; Explanation of key component symbols: Ash and slag neutralization and compounding bin 120 First heat exchanger gas-liquid separator 210 Plastic wax raw material storage tank 290 External oxygen-rich 130 Second heat exchanger gas-liquid separator 220 Oil and gas waste heat exchanger 310 Water vapor / oxygen-enriched gas distribution components 140 Third heat exchanger gas-liquid separator 230 Waste heat boiler 320 Closed pretreatment unit 150 Secondary medium oil distillation column 240 exhaust gas treatment device 330 Low-temperature pre-dechlorination melting unit 160 Three-stage heavy wax settling separator 250 exhaust 340 Low-temperature pyrolysis reactor 170 Light olefin gas 260 High-temperature gasification reforming reactor 180 Olefin gas refining tank 270 The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0019] Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0020] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0021] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms “a,” “an,” “an,” “the,” and similar words used in this application do not indicate quantity limitation and may represent singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units not listed, or may include other steps or units inherent to such processes, methods, products, or devices. The terms “connected,” “linked,” “coupled,” and similar words used in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. Example 1

[0022] Please see Figure 1The image shows a high-efficiency utilization device for white waste pollutant pyrolysis, gasification, and grading in the first embodiment of the present invention, comprising: The sealed pretreatment unit 150 consists of a sealed crusher, a negative pressure air classifier, a counter-current washing spiral, a twin-screw extrusion dewatering machine, and a permanent magnet separator connected in series, with the entire process under slight negative pressure and sealed. It is used for crushing and reducing the volume of white waste pollutants, separating light impurities from paper / fabric, washing to remove mud and organic matter, extrusion dewatering to control moisture content, and magnetic separation to remove hard metal objects, eliminating the risk of wear and slagging in subsequent reactors.

[0023] The low-temperature pre-dechlorination melting unit 160 has its feed end connected to the discharge port of the sealed pretreatment unit 150. Internally, it includes an alkaline calcium-based dechlorination agent static mixing assembly, a jacketed low-temperature heating chamber, a melting filter screen, and a chlorine-containing waste gas adsorption branch. The alkaline calcium-based dechlorination agent static mixing assembly includes a stirring and mixing assembly and a calcium-based dechlorination agent silo. The jacketed low-temperature heating chamber is a 190–260℃ heat-conducting oil jacket. The melting filter screen is a 0.8–1.5 mm filter screen. The chlorine-containing waste gas adsorption branch is an HCl alkaline spray adsorption branch. The function of this low-temperature pre-dechlorination melting unit 160 is to melt plastics at low temperatures, allowing chlorine-containing components such as PVC to release HCl, which is then fixed and adsorbed by the calcium-based components. Filtering removes inorganic impurities from sand, gravel, and glass. The molten plastic liquid is atomized and sent to the pyrolysis reactor, eliminating high-temperature chlorine corrosion at the source.

[0024] The segmented gradient pyrolysis gasification dual-reactor unit includes a downflow low-temperature pyrolysis reactor 170 and a countercurrent fluidized bed high-temperature gasification reforming reactor 180. The top of the low-temperature pyrolysis reactor 170 is connected to the molten liquid outlet of the low-temperature pre-dechlorination melting unit 160, and the bottom gas-solid mixing outlet is connected to the middle of the countercurrent fluidized bed high-temperature gasification reforming reactor 180. The low-temperature pyrolysis reactor 170 is equipped with a 320–420°C constant-temperature pyrolysis chamber. Molten plastic liquid is input through multi-layer atomizing nozzles at the top, and after atomization, it flows downwards to complete the initial macromolecular chain breaking. A rotating grid at the bottom separates the heavy reflux liquid. The countercurrent fluidized bed high-temperature gasification reforming reactor 180 is divided into upper and lower sections. The upper section, a 700–850°C high-temperature reforming and decoking zone, is filled with a honeycomb ceramic reforming carrier to remove 100% of the residual tar. The gas is cracked into small molecule syngas; the bottom of the fluidized bed is equipped with a gasifying agent distribution port and a slag discharge port, and the top outputs purified high-temperature oil and gas; the lower section 450-600℃ catalytic gasification zone is filled with nickel-based modified dolomite catalyst, and water vapor + oxygen-enriched gasifying agent are introduced. The oil and gas come into countercurrent contact from bottom to top and the catalyst comes from top to bottom, which enhances the gasification reaction.

[0025] The multi-stage fractional separation unit has its inlet end connected to the high-temperature oil and gas outlet of the segmented gradient cracking and gasification dual reactor unit. It is connected in series with a first-stage quench light gas separator 190, a second-stage medium oil distillation column 240, and a third-stage heavy wax settling separator 250. It is equipped with three-stage independent condensation heat exchange branches, gas-liquid separators (including a first heat exchange gas-liquid separator 210, a second heat exchange gas-liquid separator 220, a third heat exchange gas-liquid separator 230), and a tar deep catalytic cracking sub-line. Specifically, the three-stage tower-tank series stepped cooling and separation process is as follows: the first-stage quench tower (30-50℃) separates C1-C4 light olefin gas; the second-stage distillation tower (180-230℃) separates medium fuel oil; and the third-stage settling tank (60-100℃) retains high-melting-point heavy plastic wax. Each tower-tank has an independent condensation heat exchange branch, and the heavy tar fraction is refluxed to the fluidized bed reforming zone for circulating pyrolysis, realizing in-situ separation and extraction of the three types of products and simplifying the subsequent refining process.

[0026] The waste heat recycling energy supply unit consists of a flue gas waste heat boiler 320, an oil-gas shell-and-tube heat exchanger (oil-gas waste heat exchanger 310), a circulating thermal oil storage tank, and a gas combustion supplementary heating furnace. It is connected to the jacket of the low-temperature pre-dechlorination melting unit 160, the heat exchange chamber of the segmented gradient pyrolysis gasification dual reactor, and the reboiler of the multi-stage fractionation and separation unit for heat exchange. It recovers the sensible heat of the fluidized bed high-temperature flue gas and oil-gas, and the thermal oil is supplied to the melting unit jacket and the distillation column reboiler. The separated low-calorific-value olefin gas is used as supplementary heating fuel. Under normal continuous production conditions, no external steam or electricity is required for heating.

[0027] The product refining and storage unit consists of three independent refining tanks, including an olefin gas refining tank 270 connected to the product outlet of the primary quench light gas separator 190, an industrial fuel oil storage tank 280 connected to the product outlet of the secondary medium oil distillation tower 240, and a plastic wax raw material storage tank 290 connected to the product outlet of the tertiary heavy wax settling separator 250.

[0028] The residue resource utilization modification unit has its feed end connected to the slag discharge port of the countercurrent fluidized bed and the inorganic filter residue outlet of the low-temperature pre-dechlorination melting unit 160. The residue resource utilization modification unit includes a semi-coke grinding and modification component, an ash neutralization and compounding bin 120, and a finished product matrix discharge port, which respectively produce porous adsorption filler and soil remediation matrix. All solid slag is utilized for resource utilization, and there is no hazardous waste landfill.

[0029] In summary, the high-efficiency utilization device for white waste pollutant pyrolysis, gasification, and grading in the above embodiments of the present invention has the following beneficial effects: 1. Mix chlorine-containing white plastics and perform low-temperature dechlorination in advance to avoid high-temperature HCl corrosion of the reactor and catalyst poisoning; 2. Three-stage gradient temperature pyrolysis and gasification, with step-by-step chain breaking + catalytic gasification + high-temperature reforming, completely converts tar and significantly improves the yield of small molecule products. 3. Multi-stage cooling and fractional separation simultaneously extracts three types of liquid and gaseous products: olefin gas, fuel oil, and plastic wax, eliminating the need for complex secondary distillation. 4. Waste heat is fully recovered in stages + self-generated natural gas is used for supplemental heating, so that the system is self-sufficient in heat and reduces production energy consumption and carbon emissions; 5. The solid slag is modified and utilized in two categories: semi-coke is used to make adsorbent materials and inorganic ash is used to make soil conditioners, with no waste solid slag produced. 6. The entire process is a closed-loop system with slight negative pressure, which suppresses the fugitive emission of organic waste gas and ensures that the exhaust gas meets the standards. Example 2

[0030] In another aspect, the present invention also proposes a method for efficient utilization of white waste pollutants through pyrolysis, gasification, and classification, applied to the efficient utilization device for white waste pollutants through pyrolysis, gasification, and classification in the above-mentioned embodiment one, including steps S101~S107: S101, Closed pretreatment for impurity removal and sorting: Mixed white waste pollutants are fed into a closed crusher to be crushed to a particle size of 20-50mm. Negative pressure air separation separates light impurities from paper and fabric. Countercurrent water washing removes mud, sand, and food residue. Twin screw extrusion dewaters the material to a moisture content of ≤3%. Permanent magnet drum removes metal impurities such as iron wire and aluminum foil. The purified pure plastic material is then sent to a low-temperature pre-dechlorination melting unit. S102, Low-temperature melting and simultaneous pre-dechlorination: The pure plastic is fed into a jacketed melting chamber at 190-260°C and thoroughly mixed with a calcium-based dechlorination agent. The plastic is completely melted and liquefied, and PVC and chlorine-containing plastic products decompose and release HCl. The HCl is converted into solid calcium chloride and recovered by alkaline spraying. The melt is filtered through a sieve to remove inorganic impurities such as sand and glass. The molten plastic liquid is sent into a downflow low-temperature pyrolysis reactor by a high-pressure atomizing pump. S103, three-stage gradient pyrolysis gasification reforming: Low-temperature pyrolysis section: The molten plastic liquid is atomized and enters the downward pyrolysis reactor at 320-420℃, where the macromolecular plastic undergoes initial chain scission to generate primary oil and gas and a small amount of heavy liquid droplets; Medium-temperature catalytic gasification section: The primary oil and gas enter the 450-600℃ catalytic zone of the countercurrent fluidized bed, and water vapor-oxygen-enriched gasifying agent is introduced. The heavy components are catalytically gasified to generate small molecule hydrocarbons, H2, CO syngas; High-temperature reforming and decoking section: The mixed oil and gas rise into the 700-850℃ reforming zone, where residual tar and carbon deposits are completely cracked, eliminating tar blockage problems; S104, multi-stage fractional condensation and separation: high-temperature oil and gas sequentially enter a three-stage fractional separation device, and step cooling is used to separate and extract the products: the first stage is rapid cooling to separate light olefin fuel gas, the second stage is distillation to separate medium-quality industrial fuel oil, and the third stage is sedimentation to separate heavy plastic wax; unpyrolyzed trace amounts of tar are recycled back to the high-temperature reforming zone for further processing. S105, waste heat cascade recycling: high-temperature flue gas and high-temperature oil gas from the reactor are heated by waste heat boiler and heat exchanger to heat transfer oil, and the heat transfer oil is supplied to the melting unit and distillation tower as a heat source; the low-calorific-value olefin gas obtained by separation is burned to supplement the system heat, achieving heat self-sufficiency. S106, Refined Storage of Liquid and Gas Products: Light olefin gas is stored after desulfurization and dehydration for use in chemical synthesis and gas-fired power generation; medium fuel oil is refined after decolorization and impurity removal for use as industrial boiler fuel; heavy plastic wax is filtered and refined for use as a plastic modifying agent and waterproof wax raw material. S107, Resource-based Modification and Utilization of Solid Slag: The carbon-rich semi-coke discharged from the fluidized bed is ground and activated to make adsorption packing; the inorganic ash slag and calcium chloride by-products generated by melt filtration are mixed and neutralized, and compounded with organic matter to make soil remediation and improvement matrix. All solid slag is resource-based, and no hazardous waste is directly landfilled.

[0031] Furthermore, in S103, the recycling process of the nickel-based modified dolomite catalyst is as follows: The deactivated catalyst at the bottom of the fluidized bed is periodically discharged and sent to an air regeneration furnace at 720-780℃ to burn off the surface carbon. After regeneration, it is recycled back to the countercurrent fluidized bed catalytic gasification zone. The catalyst has a single cycle life of ≥120h.

[0032] Furthermore, the method maintains a closed operation with a slight negative pressure of -30 to -180 Pa throughout the process. All waste gas and volatile matter are uniformly collected into the activated carbon adsorption and catalytic combustion tail gas treatment device. The tail gas is discharged after meeting the standards, with no odor and no fugitive escape of organic waste gas.

[0033] Furthermore, for the continuous processing of mixed white agricultural film and takeaway plastic using the above-mentioned apparatus and method, the following conditions apply: I. Continuous processing of mixed white agricultural film and takeaway plastic Raw materials: waste PE agricultural film, PP takeaway food boxes, EPS foam plastic, and a small amount of PVC plastic mixture, with an original moisture content of 12% and containing impurities such as mud, iron wire, and paper. 1. Pretreatment: Crush to 30mm, remove paper by negative pressure air separation, wash and dehydrate with countercurrent water to a moisture content of 2.2%, remove metal by magnetic separation to obtain pure plastic raw material; 2. Pre-dechlorination melting: melting temperature 230℃, calcium-based dechlorination agent addition is 6% of plastic mass, HCl spray adsorption recovers calcium chloride solid slag, and the melt is filtered to remove sand and gravel; 3. Three-stage pyrolysis and gasification: low-temperature pyrolysis at 380℃; fluidized bed catalytic gasification at 520℃, with steam addition at 11% of the feed mass and oxygen enrichment at 30%; high-temperature reforming at 800℃, resulting in complete pyrolysis of tar. 4. Separation by grade and fraction: The first stage of the distillation column separates C1-C4 olefin gases (methane, ethylene, propylene); the second stage of the distillation column produces 0# industrial fuel oil; and the third stage of the sedimentation column produces high-melting-point polyethylene wax. 5. Waste heat recovery: The heat from oil and flue gas heats the heat transfer oil, and the self-produced low-calorific-value gas is used for supplementary heating. The system has no external steam input. 6. Solid slag treatment: Fluidized bed semi-coke grinding and activation, iodine adsorption value ≥620mg / g, used as wastewater adsorption packing; inorganic ash slag mixed with calcium chloride and organic matter to form a soil conditioner; 7. Operational monitoring data: HCl removal rate 96.2%, tar conversion rate 99.1%, carbon recovery rate 93.5%, system heat self-sufficiency rate 100%, exhaust VOCs emission <10mg / m³ 3 No foul odor was emitted.

[0034] Furthermore, for high-PVC mixed white plastic bags, the continuous processing conditions using the above-mentioned apparatus and method are as follows: Raw materials: a mixture of supermarket plastic bags and PVC plastic hoses, with a chlorine content of 2.1% by mass; melting temperature 210℃, calcium-based dechlorinating agent addition of 8%, HCl removal rate of 95.7%; fluidized bed catalytic gasification at 480℃, oxygen enrichment of 28%, water vapor addition of 9%; reforming temperature 760℃; the product olefin gas can be directly fed into a gas generator set for power generation, the medium-quality oil is supplied to the park's heating boiler, and the heavy wax is used as a lubricant for rubber and plastics; the semi-coke waste gas is adsorbed with carbon, and the ash is used for saline-alkali land improvement. The overall treatment cost is reduced by 42% compared to traditional incineration.

[0035] The functions or operational steps achieved by the above method are largely the same as those in the above device embodiments, and will not be repeated here.

[0036] The method for efficient utilization of white waste pollutants through pyrolysis, gasification, and graded classification provided in this embodiment of the invention has the same implementation principle and technical effects as the aforementioned device embodiment. For the sake of brevity, any parts not mentioned in the method embodiment can be referred to the corresponding content in the aforementioned device embodiment.

[0037] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0038] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A high-efficiency utilization device for white waste pollutants through pyrolysis, gasification, and graded processing, characterized in that: include: A closed pretreatment unit is used for crushing white waste pollutants, air separation to remove impurities, water washing to remove mud, extrusion to dewater, and magnetic separation to remove metals. The low-temperature pre-dechlorination melting unit has its feed end connected to the discharge port of the sealed pretreatment unit, and its interior is equipped with an alkaline calcium-based dechlorination agent static mixing component, a jacketed low-temperature heating chamber, a melting filter screen plate, and a chlorine-containing waste gas adsorption branch. The segmented gradient pyrolysis gasification dual-reactor unit includes a downflow low-temperature pyrolysis reactor and a countercurrent fluidized bed high-temperature gasification reforming reactor. The top of the low-temperature pyrolysis reactor is connected to the molten liquid outlet of the low-temperature pre-dechlorination melting unit, and the bottom gas-solid mixing outlet is connected to the middle of the countercurrent fluidized bed high-temperature gasification reforming reactor. The low-temperature pyrolysis reactor is equipped with a 320-420℃ constant-temperature pyrolysis chamber, and the countercurrent fluidized bed is equipped with a 450-600℃ catalytic gasification zone and a 700-850℃ high-temperature reforming decoking zone. The bottom of the countercurrent fluidized bed is equipped with a steam / oxygen-enriched gas distribution assembly, and the top is equipped with a high-temperature oil and gas total outlet. The multi-stage fractional separation unit has its inlet end connected to the high-temperature oil and gas outlet of the segmented gradient cracking and gasification dual reactor unit. It is connected in series with a first-stage quenching light gas separation tower, a second-stage medium oil distillation tower, and a third-stage heavy wax settling separation tank. It is equipped with a three-stage independent condensation heat exchange branch, a gas-liquid separator, and a tar deep catalytic cracking sub-line. The waste heat circulation energy supply unit is connected to the jacket of the low-temperature pre-dechlorination melting unit, the heat exchange chamber of the segmented gradient pyrolysis gasification dual reactor, and the reboiler of the multi-stage fractionation and separation unit, and includes a flue gas waste heat boiler, an oil and gas waste heat exchanger, a circulating heat transfer oil circuit, and a gasification low-calorific-value gas combustion supplementary heating branch. The product refining and storage unit includes an olefin gas refining tank connected to the product outlet of the primary quench light gas separator, an industrial fuel oil storage tank connected to the product outlet of the secondary medium oil distillation tower, and a plastic wax raw material storage tank connected to the product outlet of the tertiary heavy wax settling separator. The residue resource utilization modification unit has its feed end connected to the slag discharge port of the countercurrent fluidized bed and the inorganic filter residue outlet of the low-temperature pre-dechlorination melting unit. The residue resource utilization modification unit includes a semi-coke grinding and modification component, an ash neutralization and compounding bin, and a finished product matrix discharge port.

2. The high-efficiency utilization device for white waste pollutants through pyrolysis, gasification, and grading according to claim 1, characterized in that, The sealed pretreatment unit includes a sealed crusher, a negative pressure air separation chamber, a counter-current water washing screw conveyor, a twin-screw extrusion dewatering machine, and a permanent magnet drum magnetic separator. The interior of the sealed pretreatment unit maintains a slight negative pressure of -50 to -150 Pa and is equipped with an activated carbon adsorption deodorization branch for exhaust gas.

3. The high-efficiency utilization device for white waste pollutants through pyrolysis, gasification, and grading according to claim 1, characterized in that, The internal alkaline calcium-based dechlorinating agent of the low-temperature pre-dechlorination melting unit is a compound powder of calcium carbonate, calcium hydroxide, and blast furnace steel slag fine powder in a mass ratio of 3:2:

1. The melting heating temperature is controlled at 190-260℃, and the pore size of the melting filter screen plate is 0.8-1.5mm. The filtered inorganic impurities are directly sent to the residue resource modification unit. During the melting process, the HCl gas precipitated is passed into the alkaline spray adsorption branch to generate calcium chloride solid slag for simultaneous recovery.

4. The high-efficiency utilization device for white waste pollutants through pyrolysis, gasification, and graded classification according to claim 1, characterized in that, The downward-flowing cryogenic pyrolysis reactor is equipped with multiple layers of atomizing nozzles inside, and the atomized particle size of the molten plastic liquid is controlled at 20-80μm. A rotating gas-solid separation grid is set at the bottom of the cryogenic pyrolysis reactor. The primary oil and gas generated by pyrolysis are sent downward into the countercurrent fluidized bed, and the incompletely pyrolyzed heavy liquid phase is returned to the cryogenic pyrolysis reactor for recycling and pyrolysis.

5. The high-efficiency utilization device for white waste pollutants through pyrolysis, gasification, and graded classification according to claim 1, characterized in that, The high-temperature gasification reforming reactor in the countercurrent fluidized bed contains nickel-modified dolomite catalyst particles, which slowly fall from top to bottom while oil and gas come into countercurrent contact from bottom to top. The gasifying agent is a mixture of water vapor and low-concentration oxygen-enriched gas, with the water vapor feed rate being 8% to 15% of the mass of the molten plastic raw material and the oxygen enrichment volume fraction being 25% to 35%. The high-temperature reforming decoking zone is filled with a honeycomb ceramic carrier reforming catalyst, which completely decomposes the residual tar into small molecule syngas.

6. The high-efficiency utilization device for white waste pollutants through pyrolysis, gasification, and grading according to claim 1, characterized in that, The multi-stage fractionation and separation unit adopts a stepped cooling and fractionation mechanism: the first-stage rapid cooling light gas separator is cooled to 30-50°C to separate C1-C4 light olefin fuel gas; the second-stage medium oil distillation column has a top temperature of 180-230°C to separate C5-C22 industrial fuel oil; the third-stage heavy wax settling separator has a temperature of 60-100°C to retain high-melting-point plastic wax of C23 and above; the trace heavy tar produced by the third-stage separation of the multi-stage fractionation and separation unit is returned to the high-temperature reforming decoking zone for secondary cracking.

7. The high-efficiency utilization device for white waste pollutants through pyrolysis, gasification, and graded classification according to claim 1, characterized in that, The waste heat recycling unit recovers heat from high-temperature oil and gas and reactor flue gas. The heat transfer oil circulation loop supplies heat to the low-temperature pre-dechlorination melting unit and the distillation tower reboiler, respectively. The self-produced low-calorific-value olefin gas is used as supplementary heating fuel. Under normal operating conditions, the external heat input is 0.

8. A method for efficient utilization of white waste pollutants through pyrolysis, gasification, and classification, applied to the efficient utilization device for white waste pollutants through pyrolysis, gasification, and classification as described in any one of claims 1 to 7, characterized in that... Includes the following steps: Step 1: Closed pretreatment for impurity removal and sorting: The mixed white waste pollutants are fed into a closed crusher to be crushed to a particle size of 20-50mm. Negative pressure air separation separates light impurities from paper and fabric. Countercurrent water washing removes mud, sand, and food residue. Twin screw extrusion dewaters the material to a moisture content of ≤3%. Permanent magnet drum removes metal impurities such as iron wire and aluminum foil. The purified pure plastic material is then sent to a low-temperature pre-dechlorination melting unit. Step 2: Low-temperature melting and simultaneous pre-dechlorination: The pure plastic is fed into a jacketed melting chamber at 190-260°C and thoroughly mixed with a calcium-based dechlorinating agent. The plastic is completely melted and liquefied, and PVC and chlorine-containing plastic products decompose and release HCl. The HCl is converted into solid calcium chloride and recovered by alkaline spraying. The molten liquid is filtered through a sieve plate to remove inorganic impurities such as sand and glass. The molten plastic liquid is sent into a downflow low-temperature pyrolysis reactor by a high-pressure atomizing pump. Step 3: Three-stage gradient pyrolysis and reforming: Low-temperature pyrolysis section: The molten plastic liquid is atomized and enters the downward pyrolysis reactor at 320-420℃, where the macromolecular plastic undergoes initial chain scission to generate primary oil and gas and a small amount of heavy liquid droplets; Medium-temperature catalytic gasification section: The primary oil and gas enter the 450-600℃ catalytic zone of the countercurrent fluidized bed, and water vapor-oxygen-enriched gasifying agent is introduced. The heavy components are catalytically gasified to generate small molecule hydrocarbons, H2, CO syngas; High-temperature reforming and decoking section: The mixed oil and gas rise into the 700-850℃ reforming zone, where residual tar and carbon deposits are completely cracked, eliminating tar blockage problems; Step 4: Multi-stage fractional condensation and separation: High-temperature oil and gas sequentially enter a three-stage fractional separation unit, and the products are separated by step cooling: the first stage is rapid quenching to separate light olefin fuel gas, the second stage is distillation to separate medium-quality industrial fuel oil, and the third stage is sedimentation to separate heavy plastic wax; the trace amount of unpyrolyzed tar is recycled back to the high-temperature reforming zone for further processing. Step 5: Waste heat cascade recycling: High-temperature flue gas and high-temperature oil gas from the reactor are heated by a waste heat boiler and heat exchanger to heat the heat transfer oil, which is then supplied as a heat source to the melting unit and distillation column; the low-calorific-value olefin fuel gas obtained from the separation is burned to supplement the system's heat, achieving heat self-sufficiency; Step Six: Refining and Storage of Liquid and Gas Phase Products: Light olefin gas is desulfurized and dehydrated before storage for use in chemical synthesis and gas-fired power generation; medium fuel oil is decolorized and purified before being used as fuel for industrial boilers. Heavy plastic wax is filtered and refined to serve as a plastic modifier and raw material for waterproof wax. Step 7: Resource-based modification and utilization of solid slag: The carbon-rich semi-coke discharged from the fluidized bed is ground and activated to make adsorption packing; the inorganic ash slag and calcium chloride by-products generated by melt filtration are mixed and neutralized, and compounded with organic matter to make soil remediation and improvement matrix. All solid slag is resource-based, and no hazardous waste is directly landfilled.

9. The method for efficient utilization of white waste pollutants through pyrolysis, gasification, and graded processing according to claim 1, characterized in that, In step three, the recycling process for the nickel-based modified dolomite catalyst is as follows: The deactivated catalyst at the bottom of the fluidized bed is periodically discharged and sent to an air regeneration furnace at 720-780℃ to burn off the surface carbon. After regeneration, it is recycled back to the countercurrent fluidized bed catalytic gasification zone. The catalyst has a single cycle life of ≥120h.

10. The method for efficient utilization of white waste pollutants through pyrolysis, gasification, and graded classification according to claim 1, characterized in that, The method maintains a closed operation under a slight negative pressure of -30 to -180 Pa throughout the process. All waste gas and volatile matter are collected in a unified manner to the activated carbon adsorption and catalytic combustion tail gas treatment device. The tail gas is discharged after meeting the standards, with no odor and no fugitive escape of organic waste gas.

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