Recycling equipment and methods for preparing petrochemical raw materials and polymer substrates from oil sludge

Abstract

This invention discloses a recycling device and method for preparing petrochemical raw materials and polymer substrates from oily sludge, constructing a continuous treatment system of three-stage evaporation concentration + catalytic cracking. The first-stage evaporation uses a thin-film evaporator with a rake-type spiral arrangement of scrapers, suitable for high-viscosity, high-solids-content materials, achieving low-boiling-point solvent recovery. The second-stage evaporation targets asphalt tar-like materials with viscosities of 300,000 to 3,000,000 CP, recovering high-boiling-point organic solvents. The third stage uses a horizontal twin-shaft self-cleaning cracking furnace with electromagnetic induction heating, completing catalytic cracking at 450-650℃ to produce petrochemical raw materials such as ethylene and propylene. All recovered solvents and cracking products are condensed and distilled to separate into multiple types of raw materials. This invention solves the problems of traditional equipment's difficulty in handling ultra-high viscosity oily sludge, low solvent recovery rate, inability to recycle products, and easy coking and clogging of equipment. It achieves closed-loop resource utilization of all components of oily sludge, with high processing efficiency, high recycling rate, and strong environmental protection, suitable for large-scale treatment of various industrial oily sludge.

Description

Technical Field

[0001] This invention relates to the technical field of oil sludge treatment, and in particular to a recycling apparatus and method for preparing petrochemical raw materials and polymer substrates from oil sludge. Background Technology

[0002] Industrial production processes generate a large amount of oily sludge (referred to as oily sludge). Oily sludge has a complex composition, containing mineral oil, organic solvents, asphalt, colloids, solid powders, etc. It is characterized by a wide viscosity range, high solid content, easy coking, and high pollutant concentration. It is classified as hazardous waste, and direct landfilling or incineration will cause problems such as land occupation, air pollution, and resource waste.

[0003] Current Status of Oily Sludge Treatment in the Steel Industry: Steel mills generate large amounts of oily sludge during rolling, grinding, and lubrication processes. This material is a mixture of rolling oil, lubricating oil, iron powder, iron oxide scale, and water, exhibiting high viscosity and complex composition, and is classified as typical industrial hazardous waste. Current mainstream disposal methods in the industry include landfill, incineration, centrifugal separation, solvent extraction, and conventional pyrolysis.

[0004] Landfilling occupies land, and long-term oil leakage can easily cause soil and groundwater pollution; incineration has high energy consumption and easily produces harmful substances such as flue gas and dioxins, resulting in secondary pollution; physicochemical processes such as centrifugation, chemical demulsification, and solvent extraction require the addition of a large amount of reagents, have long processing procedures, low oil recovery rates, and cannot achieve simultaneous resource recovery of solid phases such as iron powder and residual carbon with oil phases; traditional pyrolysis technology has problems such as unstable product composition, high energy consumption, and easy coking and blockage.

[0005] Most existing processes only achieve hazardous waste reduction or simple oil recovery, failing to make in-depth utilization of pyrolysis products. The hydrocarbon oil and gas, liquid oil, and iron-containing residues obtained from oil sludge pyrolysis are mostly treated as low-value fuels or solid wastes, failing to connect with the petrochemical and metallurgical raw material industrial chains, resulting in low resource utilization and the inability to form a closed-loop recycling system. At the same time, they continuously increase the hazardous waste disposal costs and environmental pressures of enterprises.

[0006] Current Status of Oily Slurry Waste Treatment in the Coating, Paint, Coating and Leather Processing Industries: The production, coating and finishing processes in the coating, paint and leather processing industries generate a large amount of viscous oily slurry waste. The main components of the material are film-forming resin, mineral oil, additives, grease, organic solvents and a small amount of solid impurities. It contains organic components such as hydrocarbons, esters and high molecular prepolymers. It also has the characteristics of high viscosity, easy emulsification and difficult separation, and is classified as hazardous waste.

[0007] Currently, this type of oily slurry waste is mostly treated through outsourced disposal, incineration, or solidification and storage, resulting in complete waste of organic components and high disposal costs. A small amount is treated using simple distillation and crude pyrolysis processes, which can only recover low-end fuel oil, resulting in poor product purity and limited application scenarios. Paint and leather slurries are rich in crackable long-chain hydrocarbons and functional organic components, making them an excellent source for preparing petrochemical raw materials, polymer synthesis raw materials, and additives. However, existing technologies lack targeted integrated equipment and processes for drying and catalytic cracking, making it impossible to convert waste into high-value raw materials and to achieve a circular utilization model for the reuse of products in the production of paints, leather, and polymer materials, thus failing to fully exploit the resource value.

[0008] In summary, current treatment technologies for two major types of oily waste—oil sludge from the steel industry and oil slurry from the coatings and leather industries—generally suffer from incomplete harmlessness, low resource utilization levels, short product utilization chains, and the lack of closed-loop recycling. There is a lack of complete sets of equipment and supporting processes on the market that can simultaneously adapt to both types of materials, integrating drying, catalytic cracking, product classification and recovery, and material recycling. Therefore, developing a device and method compatible with steel plant oil sludge and coating / leather oil slurry, capable of converting waste into petrochemical raw materials and polymer material raw materials, and constructing a complete recycling process, has significant engineering application value and environmental and economic significance. Summary of the Invention

[0009] The purpose of this invention is to solve the problems in the prior art and to propose a recycling device and method for preparing petrochemical raw materials and polymer substrates from oily sludge. Targeting two types of oily waste materials, namely oily sludge from steel plants and oily slurry from the paint / leather industry, it adopts an integrated technology of drying pretreatment + catalytic cracking, combined with product graded recovery and closed-loop reuse design, which has many advantages over the prior art.

[0010] To achieve the above objectives, this invention proposes a recycling device for preparing petrochemical raw materials and polymer substrates from oil sludge. The device includes an oil sludge feed preheating tank, a double-helix conveying mechanism, a filtration device, and a rake-type scraped film evaporator, arranged sequentially in series along the material conveying direction. The double-helix conveying mechanism is located at the oil sludge output end of the oil sludge feed preheating tank and is used to feed the oil sludge into the rake-type scraped film evaporator. The filtration device is located at the output end of the double-helix conveying mechanism. The gas phase output end of the rake-type scraped film evaporator is connected to the pyrolysis product... The product distillation and recycling mechanism and the bottom solid-liquid phase output end are connected to a horizontal twin-shaft self-cleaning dryer via a melt pump. The solid-liquid phase output end of the horizontal twin-shaft self-cleaning dryer is connected to a horizontal twin-shaft self-cleaning pyrolysis furnace via an embedded twin-screw twin-spiral discharge machine. The solid-liquid phase output end of the horizontal twin-shaft self-cleaning pyrolysis furnace is connected to a slag discharge mechanism. The gas phase output end of the rake-type scraper film evaporator, the gas phase output end of the horizontal twin-shaft self-cleaning dryer, and the gas phase output end of the horizontal twin-shaft self-cleaning pyrolysis furnace are all connected to the pyrolysis product distillation and recycling mechanism.

[0011] Preferably, the pyrolysis product distillation and recycling mechanism includes condensation devices corresponding to the gas phase output ends of the rake-type scraped film evaporator, the horizontal twin-shaft self-cleaning dryer, and the horizontal twin-shaft self-cleaning pyrolysis furnace, respectively; condensation recovery tanks connected to each condensation device; a solvent recovery distillation column; a first solvent recovery tank connected to the output end of the solvent recovery distillation column; a second solvent recovery tank connected to the condensation recovery tank corresponding to the horizontal twin-shaft self-cleaning dryer; a third solvent recovery tank connected to the condensation recovery tank corresponding to the horizontal twin-shaft self-cleaning pyrolysis furnace; the output end of the condensation recovery tank corresponding to the rake-type scraped film evaporator is connected to the input end of the solvent recovery distillation column; and the output end of the third solvent recovery tank is connected to the input end of the solvent recovery distillation column.

[0012] Preferably, there are three solvent recovery distillation columns, corresponding to low-boiling-point solvents, medium-boiling-point organic solvents, and pyrolysis gaseous products, respectively, and the number of the first solvent recovery storage tanks corresponds to the number of solvent recovery distillation columns.

[0013] Preferably, each condensation unit is also connected to a tail gas treatment / incinerator.

[0014] Preferably, the rake-type scraper film evaporator has a rotating shaft inside, and a number of rake-type scrapers are provided on the rotating shaft for cooperating with the inner wall of the rake-type scraper film evaporator. The ends of the rake-type scrapers are provided with a number of rake teeth, and the rake-type scrapers are arranged in a spiral shape to make the high-viscosity material form a horizontal push flow for conveying.

[0015] Preferably, the horizontal biaxial self-cleaning pyrolysis furnace adopts an electromagnetic induction heating structure, and the furnace body is equipped with a biaxial self-cleaning mechanism and a catalyst addition port, with an operating temperature range of 450~650℃.

[0016] Preferably, the horizontal twin-shaft self-cleaning dryer is equipped with a twin-shaft self-cleaning anti-stick wall structure.

[0017] Preferably, the slag discharge mechanism includes a double-screw conveyor connected to the solid-liquid phase output end of the horizontal twin-shaft self-cleaning pyrolysis furnace, a vertical conical ribbon mixer connected to the output end of the double-screw conveyor, and a powder packaging device connected to the output end of the vertical conical ribbon mixer.

[0018] Another object of the present invention is to provide a method for a recycling apparatus for preparing petrochemical raw materials and polymer substrates from the sludge described in any of the above claims, comprising the following steps: Step S1, oil sludge preheating and pretreatment: the raw oil sludge is sent into the oil sludge feeding preheating tank for preheating and viscosity reduction, and then conveyed by a double spiral conveyor mechanism and filtered by a filtration device to remove large particulate impurities. Step S2, primary evaporation and low-boiling-point solvent recovery: the pretreated material is fed into a rake-type scraped film evaporator for primary evaporation. The material is conveyed in a horizontal flow by using rake-type spiral scrapers to evaporate the low-boiling-point solvent. After condensation, the solvent is sent to the distillation column of the cracking product distillation and recycling unit for distillation to obtain polymer material monomer raw materials. Step S3, secondary evaporation and high-boiling-point solvent recovery: The pitchy tar-like material with a viscosity of 300,000 to 3,000,000 CP after primary evaporation is metered by a melt pump and vacuum isolated before being sent to a horizontal twin-shaft self-cleaning dryer for secondary evaporation to distill off high-boiling-point organic solvents such as DMF, DMA, and DMAC. After condensation, the solvent is collected and directly supplied to the polymer material production line. Step S4: Three-stage catalytic cracking. The material after secondary evaporation is fed into a horizontal twin-screw self-cleaning pyrolysis furnace via an embedded twin-screw feeder. Electromagnetic induction heating is used to complete the catalytic cracking at 450~650℃ under the action of a catalyst, producing ethylene and propylene petrochemical gaseous products. Step S5: Recycling of cracking products by distillation. The cracked gaseous products are collected after condensation and sent to a distillation column for unified distillation with the recovered solvents at each stage. After being classified and stored, they are recycled as petrochemical raw materials and polymer base material raw materials. Step S6: Resource utilization of residue. The solid carbon ash residue after pyrolysis is cooled, and the cooled powder is used as steelmaking additive and wastewater treatment adsorbent, respectively. Step S7, exhaust gas treatment: The exhaust gas generated in each process is uniformly sent to the exhaust gas treatment / incinerator for harmless discharge.

[0019] The beneficial effects of the recycling device and method for preparing petrochemical raw materials and polymer substrates from oily sludge in this invention are as follows: 1. This invention has strong adaptability and can be compatible with two types of materials under different working conditions. It can simultaneously process oily sludge from steel plants and oily slurry waste from the coating, paint, and leather industries. Through an adjustable drying unit and an adaptable catalytic cracking system, the operating parameters can be flexibly adjusted according to the differences in material moisture content, viscosity, and organic composition. One set of equipment covers solid waste treatment scenarios in two major industries. The equipment has high versatility and reduces the repeated investment costs for enterprises. 2. Thorough and harmless treatment avoids secondary pollution. After drying to remove free moisture, the material enters the catalytic cracking unit. High-temperature cracking can completely decompose the recalcitrant organic matter and toxic and harmful components in the waste, eliminating problems such as leachate pollution from traditional landfills and toxic fumes from incineration. The entire process is carried out in a closed loop, with unified collection and treatment of oil and gas, and stabilization of solid slag, meeting the environmental protection standards for hazardous waste disposal and achieving waste reduction and harmless treatment. 3. High-value recycling of products, opening up a multi-level raw material industrial chain. For steel plant sludge, after catalytic cracking, it is graded to obtain light oil, medium and heavy oil, combustible cracked gas and iron-containing carbon-based residue: the olefin components in light oil and cracked gas can be directly used as basic petrochemical raw materials; medium oil can be processed into polymer material additives and softeners; iron-containing residue can be recycled in steel smelting and sintering processes, and residual carbon can be used as auxiliary fuel or carbon material precursor, realizing the full-component recycling of oil, gas and solid three-phase products; for oil slurry in the coating and leather industries, after catalytic cracking, the organic components undergo directional chain breaking and recombination, and the produced hydrocarbon oil and small molecule olefins can be used as raw materials in the petrochemical industry, or directly used as solvent oil, synthetic resin raw materials and functional additives for coatings, coatings and leather products, meeting the industry's own production needs; 4. Construct a closed-loop recycling system to realize resource recycling. This technology reverses the process of feeding the petrochemical raw materials and polymer raw materials produced by pyrolysis back to the production links of polymer materials, coatings, leather, etc. Waste → pyrolysis raw materials → end products → production waste forms a complete recycling chain, changing the traditional "waste disposal and raw material purchase" model, greatly reducing the raw material procurement cost of enterprises, improving the comprehensive utilization rate of resources, and meeting the requirements of circular economy development. 5. The process is continuous and stable, with low operating costs and strong industrial applicability. The pre-drying unit effectively reduces material viscosity, avoiding problems such as blockage of pipes and reactors by high-viscosity materials. The supporting catalytic system can reduce the cracking reaction temperature, increase the yield of target products, and reduce system energy consumption. The entire unit has a high degree of integration, can operate continuously, is simple to operate and maintain, and has a processing efficiency superior to traditional step-by-step processing processes, making it suitable for large-scale industrial application. 6. Significant economic and social benefits: On the one hand, it greatly reduces enterprises' hazardous waste disposal costs, while converting low-value hazardous waste into high-value chemical, metallurgical, and polymer raw materials, creating additional economic benefits; on the other hand, it reduces the consumption of fossil raw materials and lowers pollutant emissions, combining environmental, industrial, and social benefits, with broad application prospects.

[0020] The features and advantages of the present invention will be described in detail through embodiments and in conjunction with the accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0022] Figure 2 yes Figure 1 Enlarged structural diagram of the medium-oil sludge feed preheating tank, double spiral conveying mechanism, filtration equipment, rake scraper film evaporator, and melt pump.

[0023] Figure 3 yes Figure 1Enlarged structural diagram of the intermediate condenser, condensate recovery storage tank, solvent recovery distillation column, tail gas treatment / incinerator, and first solvent recovery storage tank.

[0024] Figure 4 yes Figure 1 Schematic diagrams of the following structures: horizontal twin-shaft self-cleaning dryer, embedded twin-screw twin-spiral discharge machine, horizontal twin-shaft self-cleaning pyrolysis furnace, twin-spiral conveyor, and vertical conical ribbon mixer.

[0025] Figure 5 yes Figure 1 Schematic diagram of the internal structure of a rake-type scraper film evaporator.

[0026] In the diagram: 1-Sludge feed preheating tank, 2-Double helix conveying mechanism, 3-Filtration equipment, 4-Rake scraper film evaporator, 5-Mel pump, 6-Horizontal twin-shaft self-cleaning dryer, 7-Embedded twin-screw twin-helix discharge machine, 8-Horizontal twin-shaft self-cleaning pyrolysis furnace, 9-Double helix conveyor, 10-Vertical conical ribbon mixer, 13-Condensation recovery storage tank, 14-Recovered solvent distillation column, 15-Tail gas treatment / incinerator, 41-Rake scraper, 161-First solvent recovery storage tank, 162-Second solvent recovery storage tank, 163-Third solvent recovery storage tank. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0028] In the description of this invention, it should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to or indirectly connected to the other element.

[0029] In the description of this invention, it should be noted that the terms "center," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0030] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Example 1

[0031] See Figures 1-4 This invention discloses a recycling device for preparing petrochemical raw materials and polymer substrates from oil sludge. The device is arranged in series along the material conveying direction as follows: an oil sludge feeding preheating tank 1, a double-helix conveying mechanism 2, a filtration device 3, and a rake-type scraper film evaporator 4. The oil sludge feeding preheating tank 1 is used to preheat and reduce the viscosity of the raw oil sludge, improving material flowability, and is equipped with a heat preservation structure and a stirring mechanism. The double-helix conveying mechanism 2 is used for sealed conveying to prevent oil and gas volatilization and to stably convey the pretreated oil sludge. The filtration device 3 is used to intercept large solid particles and protect the downstream evaporation and pyrolysis equipment.

[0032] The double-helix conveyor mechanism 2 is located at the sludge output end of the sludge feed preheating tank 1, and is used to smoothly convey the preheated and viscosity-reduced sludge to the filtration equipment 3. The filtration equipment 3 is used to intercept large solid particles and protect downstream equipment.

[0033] See Figure 5The rake-type scraped film evaporator 4, as a primary evaporation unit, has an internal rotating shaft with several rake-type scrapers 41 mounted on it to engage with the inner wall of the evaporator. Each rake-type scraper 41 has a number of rake teeth at its end and is arranged in a spiral pattern to facilitate the conveying of highly viscous materials in a horizontal, push-flow manner. During the rotation of the rotating shaft, the material is conveyed and scraped by the spirally arranged rake-type scrapers 41, causing the material to move downwards in a piston-like, push-flow manner. This differs from traditional hinged evaporators. The scraper-type, vertical smooth-plate evaporator is specifically designed for high-viscosity, high-solids-content sludge. A gas phase outlet is located at the top, connected to a corresponding first condensation unit 121 and a condensation recovery tank 13. The output of the condensation recovery tank 13 is connected to a solvent recovery distillation column 14, which in turn is connected to a first solvent recovery tank 161. The gas phase output of the scraper-type thin-film evaporator 4 is connected to a cracking product distillation and recycling mechanism, while its bottom solid-liquid phase output is connected to a horizontal twin-shaft self-cleaning dryer 6 via a melt pump 5. The scraper-type thin-film evaporator 4 contains scraper blades 41 arranged in a spiral pattern. During operation, the material is conveyed downwards in a push-flow manner, making it particularly suitable for high-viscosity, high-solids-content sludge.

[0034] The horizontal twin-shaft self-cleaning dryer 6 serves as a secondary evaporation unit. Designed for ultra-high viscosity materials with pitchy tar-like textures ranging from 300,000 to 3,000,000 CP, it features staggered T-shaped scrapers on both shafts. The gap between the outer edge of the scraper and the inner wall of the cylinder is 2-5 mm. As the twin shafts rotate, the scrapers mesh with each other to remove adhering substances from the wall. The twin-shaft self-cleaning structure prevents materials from sticking to the wall and coking, and evaporates high-boiling-point organic solvents such as DMF, DMA, and DMAC. The gas phase end of the horizontal twin-shaft self-cleaning dryer 6 is connected to another corresponding second condensation device 122 and a condensation recovery storage tank 13. The output end of the condensation recovery storage tank 13 is directly connected to the second solvent recovery storage tank 162, directly conveying the material to the polymer material production line as raw material.

[0035] The solid-liquid phase output of the horizontal twin-screw self-cleaning dryer 6 is connected to the horizontal twin-screw self-cleaning pyrolysis furnace 8 via an embedded twin-screw double-spiral discharge machine 7. The horizontal twin-screw self-cleaning pyrolysis furnace 8, as a three-stage evaporation unit, is equipped with a twin-screw self-cleaning anti-sticking wall structure and is used to process asphalt tar-like materials with a viscosity of 300,000 to 3,000,000 CP. The horizontal twin-screw self-cleaning pyrolysis furnace 8 adopts an electromagnetic induction heating structure, and the furnace body is equipped with a twin-screw self-cleaning mechanism and a catalyst addition port, with an operating temperature range of 450–650℃. The gas phase end is connected to the corresponding third condensation device 123 and condensation recovery storage tank 13. The output end of the condensation recovery storage tank 13 is connected to the third solvent recovery storage tank 163, and the output end of the third solvent recovery storage tank 163 is connected to the solvent recovery distillation column 14. The embedded twin-screw double-spiral discharge machine 7 has a strong pushing structure and can transport ultra-high viscosity materials with extremely poor flowability; its sealed design ensures a vacuum environment.

[0036] The solid-liquid phase output end of the horizontal twin-shaft self-cleaning pyrolysis furnace 8 is connected to the slag discharge mechanism, which includes a twin-screw conveyor 9, a vertical conical ribbon mixer 10, and a powder packaging device connected in sequence. The twin-screw conveyor 9 conveys the solid carbon ash residue after pyrolysis in a closed manner, the vertical conical ribbon mixer 10 is used for closed cooling of the high-temperature carbon ash residue, the ribbon mixing ensures uniform cooling, and the powder packaging device automatically packages and seals the cooled carbon ash powder.

[0037] Each condensation unit is also connected to a tail gas treatment / incinerator 15. The tail gas from all processes of the entire unit is collected, treated to render it harmless, and then discharged.

[0038] Among them, there are three solvent recovery distillation columns 14, which correspond to low-boiling-point solvents, medium-boiling-point organic solvents, and pyrolysis gas phase products, respectively. The number of first solvent recovery storage tanks 161 corresponds to the number of solvent recovery distillation columns 14. A three-stage gradient temperature-controlled distillation module is set up to accurately separate and purify the solvents and pyrolysis gas phase products at each stage. Multiple sets of solvent recovery storage tanks are used to store solvents with different boiling points and different components and pyrolysis products in different areas. Example 2

[0039] This embodiment describes a method for treating oil sludge using the aforementioned apparatus.

[0040] The object processed in this embodiment is industrial high-viscosity sludge containing asphalt tar, with an initial viscosity of 5000~10000CP, a solid content of 40%~60%, and containing components such as low-boiling-point mixed solvents, DMF, DMAC, asphalt, and heavy tar.

[0041] Includes the following steps: Step S1, preheating and pretreatment of sludge: The raw sludge is fed into the sludge feed preheating tank 1 for preheating and viscosity reduction. The preheating temperature is controlled at 40~60℃ to reduce the initial viscosity. The sludge is then conveyed by the double spiral conveyor mechanism 2 and filtered by the filtration equipment (3) to remove large particulate impurities. Solid impurities with a particle size ≥2mm are screened out to ensure the stable operation of subsequent equipment. Step S2, primary evaporation and low-boiling-point solvent recovery (low-boiling-point solvent recovery): The pretreated material is fed into a rake-type scraped film evaporator 4 for primary evaporation. Inside the equipment, rake-type scrapers are spirally arranged along the cylinder, rotating at 5~10 r / min. The material forms a uniform liquid film along the cylinder wall and moves downward in a push flow. The evaporation temperature is 70~120℃, and the system operates under negative pressure (-0.06~-0.09MPa). The evaporated low-boiling-point solvent vapor is cooled to liquid state by a condenser and stored in an intermediate storage tank, which is then sent to the solvent recovery distillation column 14. Compared with the traditional hinged scraped evaporator, high-solids and high-viscosity materials are not retained, the liquid film is uniform, and the low-boiling-point solvent recovery rate is ≥92%. Step S3; Secondary evaporation and high-boiling-point solvent recovery (high-boiling-point solvent recovery): The material viscosity rises to 800,000 to 2,000,000 CP, appearing as pitch-tar; it is precisely metered and transported by melt pump 5, while the vacuum isolation structure ensures independent negative pressure between the front and rear units; the material enters the horizontal twin-shaft self-cleaning dryer 6, with an evaporation temperature of 150 to 220°C and negative pressure operation; high-boiling-point organic solvents such as DMF, DMA, and DMAC are evaporated out, condensed, and stored in solvent recovery storage tanks D and E, and directly transported to the polymer material production workshop for use as raw materials; the twin-shaft self-cleaning mechanism continuously scrapes the material off the cylinder wall, with no sticking or clogging, and the high-boiling-point solvent recovery rate is ≥88%.

[0042] Step S4, three-stage catalytic cracking (petrochemical feedstock preparation): The material after secondary evaporation is fed into a horizontal twin-screw self-cleaning cracking furnace 8 via an embedded twin-screw feeder 7. A special catalytic cracking catalyst for oil sludge is added to the furnace at a rate of 1% to 3% of the material mass. Electromagnetic induction heating is activated to control the furnace temperature to be stable at 500-600℃, and negative pressure cracking is performed. Asphaltene and heavy tar are fully cracked to generate small-molecule petrochemical gaseous products such as ethylene and propylene. The gaseous products are condensed and collected in the corresponding condensate recovery storage tank 13, and then uniformly transported to the solvent recovery distillation tower 14. The furnace body's twin-screw self-cleaning mechanism removes coke in real time, and the equipment can operate continuously and stably for more than 30 days.

[0043] Step S5: The cracking products are distilled and reused. The cracked gas phase products are condensed and collected, and sent to a distillation column for unified distillation with the recovered solvents at each stage. After being classified and stored, they are recycled as petrochemical raw materials and polymer base material raw materials. The recovered solvent distillation column 14 is equipped with three temperature control zones, corresponding to low-boiling-point solvents, medium-boiling-point organic solvents, and cracked gas phase products, respectively. After distillation, the products are classified and stored in solvent recovery storage tanks A, B, and C according to their components. The purity of the products in the storage tanks meets industrial requirements and can be directly supplied as monomer raw materials for PE and PP polymer materials and basic petrochemical raw materials.

[0044] Step S6: The residue is recycled and fed into the vertical conical ribbon mixer 10 via a double helix conveyor 9 and cooled to room temperature in a sealed air-cooled manner. The cooled carbon ash powder is packaged by an automatic packaging device, with 60% used as a carbonaceous additive for steelmaking and 40% fed into the wastewater treatment system as a waste activated carbon adsorbent. Step S7, exhaust gas treatment: All waste gas generated by the evaporation and pyrolysis units of the entire set of equipment is collected into the exhaust gas treatment / incinerator, and discharged after being treated by high-temperature incineration to meet the standards.

[0045] Running result: The complete set of equipment of this invention can process an average of 20 tons of high-viscosity oil sludge per day after 30 days of continuous operation. The comprehensive recovery rate of various organic solvents is ≥90%, and the purity of the distillation product meets the standards for use in polymer materials and the petrochemical industry. The petrochemical feedstock yield of the catalytic cracking unit is ≥85%; All solid residues are utilized as resources, and there is no discharge of solid waste. The equipment operates without any blockages or severe coking, operates under closed negative pressure, and has no organic solvent volatilization or leakage, with exhaust gas emissions meeting standards. By building a complete circular industrial chain, the comprehensive treatment cost of oil sludge is reduced by 35%, and the resource-based products generate significant economic benefits. All standard parts used in this application can be purchased from the market. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the existing technology. The internal components of the electric slide rail, cylinder, welding machine, electric telescopic rod and controller all adopt conventional models in the existing technology, and their internal structure belongs to the existing technology structure. Workers can complete the normal operation of them according to the existing technical manual. In addition, the circuit connection adopts the conventional connection method in the existing technology, and will not be described in detail here.

[0046] It should be noted that although the above embodiments have been described herein, this does not limit the scope of patent protection for this invention. Therefore, any changes and modifications made to the embodiments described herein based on the innovative concept of this invention, or equivalent structural or procedural transformations made using the description and drawings of this invention, directly or indirectly applying the above technical solutions to other related technical fields, are all included within the scope of protection of this invention.

Claims

1. A recycling device for preparing petrochemical raw materials and polymer substrates from oil sludge, comprising an oil sludge feeding preheating tank (1), a double-helix conveying mechanism (2), a filtration device (3), and a rake-type scraped film evaporator (4) arranged in series along the material conveying direction, characterized in that: The double-helix conveying mechanism (2) is located at the oil sludge output end of the oil sludge feed preheating tank (1) and is used to feed the oil sludge into the rake-type scraped film evaporator (4). The filtration device (3) is located at the output end of the double-helix conveying mechanism (2). The gas phase output end of the rake-type scraped film evaporator (4) is connected to the cracking product distillation and reuse mechanism, and the bottom solid-liquid phase output end is connected to the horizontal twin-shaft self-cleaning dryer (6) via the melt pump (5). The solid-liquid phase output end of the horizontal twin-shaft self-cleaning dryer (6) is connected to the horizontal twin-shaft self-cleaning cracking furnace (8) via the embedded twin-screw double-helix discharge machine (7). The solid-liquid phase output end of the horizontal twin-shaft self-cleaning cracking furnace (8) is connected to the slag discharge mechanism. The gas phase output end of the rake-type scraped film evaporator (4), the gas phase output end of the horizontal twin-shaft self-cleaning dryer (6), and the gas phase output end of the horizontal twin-shaft self-cleaning cracking furnace (8) are all connected to the cracking product distillation and reuse mechanism.

2. The recycling device for preparing petrochemical raw materials and polymer substrates from oil sludge as described in claim 1, characterized in that: The pyrolysis product distillation and reuse mechanism includes a first condensing device (121) connected to the gas phase output end of the rake-type scraped film evaporator (4), a second condensing device (122) connected to the gas phase output end of the horizontal twin-shaft self-cleaning dryer (6), a third condensing device (123) connected to the gas phase output end of the horizontal twin-shaft self-cleaning pyrolysis furnace (8), and a condensate recovery storage tank (13) connected to the output end of each condensing device. The pyrolysis product distillation and reuse mechanism also includes a solvent recovery distillation column (14) and a condensate recovery storage tank (13) connected to the output end of the solvent recovery distillation column (14). The first solvent recovery storage tank (161) is connected to the end of the horizontal twin-shaft self-cleaning dryer (6), the second solvent recovery storage tank (162) is connected to the condensation recovery storage tank (13) corresponding to the horizontal twin-shaft self-cleaning pyrolysis furnace (8), and the third solvent recovery storage tank (163) is connected to the condensation recovery storage tank (13) corresponding to the horizontal twin-shaft self-cleaning pyrolysis furnace (8). The output end of the condensation recovery storage tank (13) corresponding to the rake-type scraped film evaporator (4) is connected to the input end of the solvent recovery distillation column (14), and the output end of the third solvent recovery storage tank (163) is connected to the input end of the solvent recovery distillation column (14).

3. The recycling device for preparing petrochemical raw materials and polymer substrates from oil sludge as described in claim 2, characterized in that: There are three solvent recovery distillation columns (14), which correspond to low-boiling-point solvents, medium-boiling-point organic solvents, and pyrolysis gas phase products, respectively. The number of the first solvent recovery storage tank (161) corresponds to the number of solvent recovery distillation columns (14).

4. The recycling device for preparing petrochemical raw materials and polymer substrates from oil sludge as described in claim 1, characterized in that: Each condensation unit is also connected to a tail gas treatment / incinerator (15).

5. The recycling device for preparing petrochemical raw materials and polymer substrates from oil sludge as described in claim 1, characterized in that: The rake-type scraper film evaporator (4) is provided with a rotating shaft inside, and a number of rake-type scrapers (41) are provided on the rotating shaft for cooperating with the inner wall of the rake-type scraper film evaporator (4). The rake-type scrapers (41) are provided with a number of rake teeth at the end. The rake-type scrapers (41) are arranged in a spiral shape to make the high-viscosity material form a horizontal push flow for conveying.

6. The recycling device for preparing petrochemical raw materials and polymer substrates from oil sludge as described in claim 1, characterized in that: The horizontal biaxial self-cleaning pyrolysis furnace (8) adopts an electromagnetic induction heating structure, and the furnace body is equipped with a biaxial self-cleaning mechanism and a catalyst addition port. The working temperature range is 450~650℃.

7. The recycling device for preparing petrochemical raw materials and polymer substrates from oil sludge as described in claim 1, characterized in that: The horizontal twin-shaft self-cleaning dryer (6) is equipped with a twin-shaft self-cleaning anti-stick wall structure.

8. The recycling device for preparing petrochemical raw materials and polymer substrates from oil sludge as described in claim 1, characterized in that: The slag discharge mechanism includes a double helix conveyor (9) connected to the solid-liquid phase output end of the horizontal twin-shaft self-cleaning pyrolysis furnace (8), a vertical conical ribbon mixer (10) connected to the output end of the double helix conveyor (9), and a powder packaging device connected to the output end of the vertical conical ribbon mixer (10).

9. A method for using the recycling apparatus for preparing petrochemical raw materials and polymer substrates from oil sludge according to any one of claims 1-8, characterized in that, Includes the following steps: Step S1, preheating and pretreatment of sludge: the original sludge is sent into the sludge feed preheating tank (1) for preheating and viscosity reduction, and then conveyed by the double spiral conveying mechanism (2) and filtered by the filtration equipment (3) to remove large particulate impurities. Step S2, primary evaporation and low-boiling-point solvent recovery: the pretreated material is sent to the rake-type scraped film evaporator (4) for primary evaporation. The material is conveyed in a horizontal flow by using the rake-type spiral arrangement of scrapers to evaporate the low-boiling-point solvent. After condensation, the solvent is sent to the distillation column of the cracking product distillation and recycling mechanism for distillation to obtain polymer material monomer raw materials. Step S3, secondary evaporation and high-boiling-point solvent recovery: after primary evaporation, the asphalt tar-like material with a viscosity of 300,000 to 3,000,000 CP is metered by a melt pump (5), vacuum isolated, and then sent to a horizontal twin-shaft self-cleaning dryer (6) for secondary evaporation to distill off high-boiling-point organic solvents such as DMF, DMA, and DMAC. After condensation, the solvent is collected and directly supplied to the polymer material production line. Step S4, three-stage catalytic cracking: the material after secondary evaporation is fed into a horizontal twin-screw self-cleaning cracking furnace (8) via an embedded twin-screw double-helix discharge machine (7). Electromagnetic induction heating is used to complete the catalytic cracking at 450~650℃ under the action of a catalyst, generating ethylene and propylene petrochemical gaseous products; Step S5: Recycling of cracking products by distillation. The cracked gaseous products are collected after condensation and sent to a distillation column for unified distillation with the recovered solvents at each stage. After being classified and stored, they are recycled as petrochemical raw materials and polymer base material raw materials. Step S6: Resource utilization of residue. The solid carbon ash residue after pyrolysis is cooled, and the cooled powder is used as steelmaking additive and wastewater treatment adsorbent, respectively. Step S7, exhaust gas treatment: The exhaust gas generated in each process is uniformly sent to the exhaust gas treatment / incinerator for harmless discharge.

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