Method and device for treating inferior oil and waste plastics through slurry reactor

Abstract

The invention discloses a method and device for treating inferior oil and waste plastics through a slurry bed, and the method comprises the following steps: S1, mixing the inferior oil with hydrogen, preheating, conveying to a slurry bed reactor for reaction, enabling a product to enter a thermal high-pressure separator for reaction, carrying out gas-liquid separation to obtain a gas-phase component and a liquid-phase component, washing the gas-phase component with water, and discharging; and S2, mixing the liquid phase component obtained in the step S1 with waste plastic, then carrying out thermal cracking reaction in a waste plastic cracking furnace, fractionating the product to obtain a light fraction and a heavy fraction, separating the heavy fraction into a heavy component and a light component through a centrifugal separation device, circulating the heavy component to the slurry bed reactor for reaction, and treating the light fraction and the light component to obtain the product.

Description

Technical Field

[0001] The present invention belongs to the field of petrochemical industry, and particularly relates to a method and device for treating inferior oil and waste plastics in a slurry bed. Background Art

[0002] Plastic is one of the major inventions of mankind since the 20th century. With the rise of the plastic industry in the mid-20th century, mankind has entered the plastic era. The application of plastic products has penetrated into every corner of society. Plastics are everywhere, from industrial production to clothing, food, housing and transportation. The rapid development of the plastic industry has also brought a series of social problems caused by waste plastics and garbage waste plastics that people do not want to see. Every year, a large amount of waste plastics accumulates in various countries around the world, bringing huge environmental pressure to human society.

[0003] The slurry bed hydrogenation process is one of the ideal methods for realizing the lightening of heavy oil. The use of the heavy oil slurry bed hydrocracking technology is a suitable process technology that is technically and economically feasible and conforms to the development trend of improving resource utilization rate.

[0004] The amount of waste plastics increases year by year, which has seriously affected the safety of the atmosphere, soil, water source, etc. in China. Traditional treatment methods for waste plastics such as landfilling and incineration will bring some environmental problems. The waste plastic pyrolysis technology can turn "waste" into "treasure", and has good environmental optimization effects and social and economic benefits.

[0005] In view of the pain points and difficulties faced in the process of plastic utilization or treatment, it is urgent to develop a technology for pyrolyzing waste plastics by a slurry bed process.

[0006] Chinese Patent CN101074385A describes a continuous pyrolysis process and equipment for waste plastics. It realizes continuous pyrolysis by heating the raw materials with a solid heat carrier carrying heat that is mixed with the raw materials and moves in the same direction in the pyrolyzer. The pyrolysis temperature is 380-500°C, and the addition amount of the heat-conducting balls is about 40 times that of the waste plastics added. The heat-conducting balls need to be continuously recycled and regenerated. The pyrolysis gas needs to pass through a fixed bed for secondary pyrolysis, cooling, and fractionation to obtain gasoline and diesel. The cyclic carbon burning and regeneration of a large number of high-temperature heat-conducting balls result in a complex production device structure, high energy consumption, difficult operation, and a large amount of waste gas and solid waste emissions for treatment.

[0007] Patent CN102260515A introduces a waste plastic pyrolysis treatment device. The reaction kettle is filled with low-melting metals or salts that can be heated to a molten state. The metal or salt is lead or potassium chloride, sodium chloride or a mixed salt thereof; the feeding device presses the waste plastics into the molten metal or molten salt. Since the density of plastics and metals or molten salts differs greatly, it is very difficult to achieve uniform mixing and contact between the two at high temperatures.

[0008] Patent CN109355099A discloses a method for co-processing solid waste and coal tar to produce fuel oil. First, the phenolic components in the light fraction of coal tar are extracted; then, the heavy fraction oil of coal tar is pre-hydrogenated to promote the conversion of resins and asphaltenes in the heavy fraction oil into partially hydrogenated polycyclic aromatic hydrocarbons, improving the hydrogen supply performance of the heavy fraction oil; finally, the liquid phase products with different distillation ranges in the separator after hydrogenation are mixed with solid waste and fed into the co-processing reaction device to obtain gasoline, diesel, and phenolic products, realizing the co-processing of solid waste and coal. This invention combines the processes of phenolic extraction from coal tar, hydrogenation of heavy fractions, and co-processing with solid waste, provides a large amount of solvent oil with good hydrogen supply performance for the liquefaction treatment of solid waste, realizes the molecular utilization of coal tar and the large-scale, clean, and efficient utilization of solid waste, greatly improves the conversion efficiency of coal tar and solid waste, and has the advantages of low hydrogen consumption, high oil yield, good economic benefits, and being conducive to the long-term and large-scale operation of the device, but the process flow is relatively complex. Summary of the Invention

[0009] The purpose of the present invention is to provide a method and device for treating inferior oil and waste plastics in a slurry bed to solve the problems of easy coking in the reaction and the complex structure and process flow of the production device in the prior art.

[0010] To achieve the above purpose, the present invention provides a method for treating inferior oil and waste plastics in a slurry bed, including the following steps:

[0011] S1, mixing the inferior oil with hydrogen, preheating it, and then transporting it to a slurry bed reactor for reaction. The product enters a hot high-pressure separator for reaction and gas-liquid separation to obtain a gas-phase component and a liquid-phase component. The gas-phase component is discharged after being washed with water.

[0012] S2, mixing the liquid-phase component obtained in step S1 with waste plastics and conducting a thermal cracking reaction in a waste plastic cracking furnace. The product is fractionated to obtain a light fraction and a heavy fraction. The heavy fraction is separated by centrifugation into a heavy component and a light component. The heavy component is recycled to the slurry bed reactor for reaction, and the light fraction and the light component are the products obtained after treatment.

[0013] In the method for treating inferior oil and waste plastics in a slurry bed according to the present invention, the reaction temperature in the slurry bed reactor is 380 - 500 °C, the reaction pressure is 8 - 25 MPa, the liquid hourly space velocity is 0.1 - 1.2 h -1 , the hydrogen-oil ratio is 600 - 1000, and preferably the reaction temperature is 440 - 480 °C, the reaction pressure is 8 - 16 MPa, and the liquid hourly space velocity is 0.3 - 1.0 h -1 .

[0014] In the method for treating inferior oil and waste plastics in a slurry bed according to the present invention, the reaction temperature in the hot high-pressure separator is 440 - 480 °C, and the reaction pressure is 8 - 20 MPa.

[0015] For the method for treating inferior oil and waste plastics in a slurry bed according to the present invention, the reaction temperature in the waste plastic cracking furnace is 420 - 500 °C, and the reaction pressure is 8 - 20 MPa.

[0016] For the method for treating inferior oil and waste plastics in a slurry bed according to the present invention, the weight ratio of waste plastics to the liquid phase component in step S2 is 1:5 - 10.

[0017] For the method for treating inferior oil and waste plastics in a slurry bed according to the present invention, during fractionation in step S2, the cutting temperature is 400 - 420 °C, the top temperature of the fractionation tower is 150 - 180 °C, the bottom temperature is 380 - 420 °C, and the top pressure is 0.05 - 0.2 Mpa.

[0018] For the method for treating inferior oil and waste plastics in a slurry bed according to the present invention, the inferior oil is at least one of coal tar, catalytic oil slurry, high - sulfur and high - metal residue oil, atmospheric residue, vacuum residue, ultra - viscous heavy crude oil, and oil - sand bitumen.

[0019] For the method for treating inferior oil and waste plastics in a slurry bed according to the present invention, when reacting in a slurry bed reactor in step S1, an oil - soluble catalyst with a hydrogenation function needs to be added. The active components of the oil - soluble catalyst are one or more of Mu, Ni, Co, and Fe, and the catalyst concentration is 10 - 1000 ppm in terms of metal.

[0020] For the method for treating inferior oil and waste plastics in a slurry bed according to the present invention, the waste plastics are waste plastics pretreated by crushing, screening, and metal removal. No specific limitations are imposed on the source and type of the waste plastics. For example, they can be one or more of polyethylene (PE), polypropylene (PP), polystyrene (PS), expanded polystyrene (PSF), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyurethane (PU), and ABS plastics.

[0021] To achieve the above object, the present invention further provides a device for treating inferior oil and waste plastics in a slurry bed, comprising an inferior oil feeding system, a slurry bed reactor, a hot high-pressure separator, a gas-phase product treatment system, a waste plastic pyrolysis furnace, a fractionation device, a separation device and a product tank; the inferior oil feeding system includes a raw material tank, a raw material pump and a heater connected in sequence, the outlet of the heater is communicated with the inlet of the slurry bed reactor, the outlet of the slurry bed reactor is communicated with the inlet of the hot high-pressure separator, the hot high-pressure separator is provided with a gas-phase component pipeline and a liquid-phase component pipeline, the gas-phase product treatment system includes a buffer tank and an absorption tower, and the gas-phase component pipeline is sequentially communicated with the buffer tank and the absorption tower; the liquid-phase component pipeline is communicated with the inlet of the waste plastic pyrolysis furnace, the outlet of the waste plastic pyrolysis furnace is communicated with the fractionation device, the fractionation device is provided with a light fraction pipeline and a heavy fraction pipeline, the light fraction pipeline is communicated with the product tank, the heavy fraction pipeline is communicated with the inlet of the separation device, the separation device is provided with a heavy component pipeline and a light component pipeline, the heavy component pipeline is communicated with the feeding system or directly communicated with the slurry bed reactor, and the light component is communicated with the product tank.

[0022] In the device for treating inferior oil and waste plastics in a slurry bed according to the present invention, the number of the slurry bed reactors is one or more, and multiple slurry bed reactors are arranged in series.

[0023] Advantages of the present invention:

[0024] 1. While processing inferior heavy oil using the slurry bed process, waste plastics are processed by means of pyrolysis using waste heat. The pyrolysis reaction needs to be carried out under high temperature and high pressure, and the present invention can process waste plastics while saving energy consumption, improve the conversion rate of oil products, and achieve the purpose of environmental protection.

[0025] 2. A fractionation device and a separation device are arranged after the waste plastic pyrolysis furnace to separate the oil products after pyrolysis. The heavier part of the oil is circulated to the slurry bed reactor for continuous feeding, and the light oil products are stored in the product tank or used for subsequent processes. It is possible to improve the conversion rate of oil products while reducing the consumption of catalysts.

[0026] 3. The device and method of the present invention can be provided with two or more slurry bed reactors that can be arranged in series or operated independently. The slurry bed reactor adopts a bare-barrel structure. It can reduce the coking and blockage conditions, ensure that the cracking and hydrogenation reactions can be carried out under suitable environmental conditions, thereby being beneficial to improving the conversion rate of the feedstock oil and the light oil yield. Control the coking amount in the process of the inferior oil slurry bed hydrogenation reaction, effectively prevent the blockage of the outlet valve and pipeline of the hot high-pressure separator caused by coking, and further improve the total reaction conversion rate, realizing the long-term stable operation of the device. Description of the Drawings

[0027] Figure 1 This is a schematic structural diagram of a device for treating inferior oil and waste plastics in a slurry bed according to the present invention.

[0028] Among them, the reference numerals:

[0029] 1, raw material tank; 2, raw material pump; 3, preheater; 4, first slurry bed reactor; 5, second slurry bed reactor; 6, hot high-pressure separator; 7, buffer tank; 8, water washing tower; 9, waste plastic pyrolysis furnace; 10, fractionation device; 11, separation device; 12, product tank. Specific embodiments

[0030] The present invention will be specifically described below through embodiments. It is necessary to point out here that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the protection scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention according to the above content of the present invention.

[0031] Figure 1The figure shows a schematic diagram of an apparatus for treating inferior oil and waste plastics in a slurry bed according to the present invention. This set of apparatus includes two slurry bed reactors. It includes a raw material tank 1, and the raw material tank 1 is connected to a raw material pump 2. The present invention does not particularly limit the types of the raw material tank 1 and the raw material pump 2. The raw material pump 2 can be a positive displacement plunger raw material pump. The raw material pump 2 is connected to a preheater 3, and the preheater 3 is connected to a first slurry bed reactor 4. The first slurry bed reactor 4 is connected in series with a second slurry bed reactor 5. The first slurry bed reactor 4 and the second slurry bed reactor 5 can be selected as empty barrel type slurry bed reactors, which can reduce coking and blockage. The tops of the first slurry bed reactor 4 and the second slurry bed reactor 5 are provided with outlets, and the bottoms are provided with inlets. The inlets can be conical feed inlets, which can prevent material accumulation. The outlets can be arc-shaped side discharge outlets, which can ensure smooth discharging. However, the present invention does not particularly limit the forms of the discharge outlets and feed inlets of the slurry bed reactors. In other embodiments, they can be set to other forms according to actual production needs; the heater 3 is connected to the bottom inlet of the first slurry bed reactor 4. The top outlet of the first slurry bed reactor 4 is connected to the bottom inlet of the second slurry bed reactor 5. The top outlet of the second slurry bed reactor 5 is connected to a hot high-pressure separator 6. The hot high-pressure separator 6 is provided with a gas-phase component pipeline and a liquid-phase component pipeline. The gas pipeline is connected to a buffer tank 7, and the buffer tank 7 is connected to a water washing tower 8. The liquid pipeline is connected to a waste plastic pyrolysis furnace 9. The waste plastic pyrolysis furnace 9 is connected to a fractionation device 10. The fractionation device 10 is provided with a light fraction pipeline and a heavy fraction pipeline. The light fraction pipeline is connected to a product tank 12. The heavy fraction pipeline is connected to a separation device 11. The separation device 11 is provided with a heavy component pipeline and a light component pipeline. The heavy component pipeline is connected to the raw material pump 2. The separated heavy components are mixed with the inferior oil and then enter the slurry bed reactor 4 again. In another embodiment, the heavy fraction pipeline can also be directly connected to the slurry bed reactor 4 as an independent feeding system. The light component pipeline is connected to the product tank 12.

[0032] In the present invention, the fractionation device 10 can be a combination of one or several separation devices such as a hot high-pressure separation tank, a hot low-pressure separation tank, a cold high-pressure separation tank, a cold low-pressure separation tank, a hydrocyclone, a flash tower, an atmospheric distillation tower, a vacuum distillation tower, an extraction tower, etc. Preferably, it is an atmospheric distillation tower.

[0033] The present invention will be further described below through examples. However, the following examples do not limit the scope claimed by the present invention.

[0034] Source of raw materials or equipment: A certain mixed residue oil, the properties are shown in Table 1

[0035] Table 1. Properties of vacuum residue

[0036]

[0037]

[0038] Examples 1 to 3

[0039] Examples 1 to 3 adopt the process flow as Figure 1 shown. After hydrogen and raw materials are preheated in the preheater 3, they are input into the first slurry bed reactor 4 and the second slurry bed reactor 5 for reaction. The obtained product continues to react in the hot high-pressure separator 6 and gas-liquid separation is carried out. The gas after gas-liquid separation is discharged after being washed by the buffer tank 7 and the water washing tower 8. The liquid phase after gas-liquid separation enters the waste plastic pyrolysis furnace 9, and heat pyrolysis reaction is carried out with the waste plastic that has been pretreated by crushing, screening and metal removal by using the waste heat of the liquid phase. The liquid phase oil product after the reaction enters the fractionation device 10 for fractionation. The light fraction enters the product tank 12. The bottom tower heavy fraction is separated into two streams of materials by the separation device 11. The heavier fraction of the oil product is recycled back to the feed inlet to form the reaction feed with the raw materials, and after being preheated, it enters the first slurry bed reactor 4 again. The light fraction enters the product tank 12 for storage or subsequent processes.

[0040] The properties of the raw material oil used are shown in Table 1, and the process operation conditions are shown in Table 2:

[0041] Table 2. Process conditions of the examples

[0042]

[0043]

[0044] The evaluation results are shown in Table 3:

[0045] Table 3. Evaluation results of the examples

[0046]

[0047]

[0048] It can be seen from the operation of the examples that the method of the present invention has a high conversion rate, a low content of toluene insoluble substances, realizes the resource utilization of waste, and reduces the overall energy consumption of the device by using waste heat pyrolysis.

[0049] Of course, the present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for treating low-quality oil and waste plastics in a slurry bed, characterized in that: The following steps are involved: S1, mixing low-quality oil with hydrogen, preheating and transporting to a slurry bed reactor for reaction, the product enters a hot high-pressure separator for reaction and gas-liquid separation to obtain gas phase components and liquid phase components, and the gas phase components are discharged after being washed with water; S2, the liquid component obtained in step S1 is mixed with waste plastics and subjected to thermal cracking reaction in a waste plastic cracking furnace, and the product is fractionated to obtain a light fraction and a heavy fraction, the heavy fraction is centrifuged to be separated into a heavy fraction and a light component, the heavy fraction is circulated to a slurry bed reactor for reaction, and the light fraction and the light component are the products obtained after treatment.

2. The method for treating low-quality oil and waste plastics in a slurry bed according to claim 1, characterized in that: The reaction temperature in the slurry bed reactor is 380-500°C, the reaction pressure is 8-25MPa, and the liquid hourly space velocity is 0.1-1.2h -1 , the hydrogen-to-oil ratio is 600-1000.

3. The method for treating low-quality oil and waste plastics in a slurry bed according to claim 1, characterized in that: The reaction temperature in the hot high-pressure separator is 440-480° C., and the reaction pressure is 8-20 MPa.

4. The method for treating low-quality oil and waste plastics in a slurry bed according to claim 1, characterized in that: The reaction temperature in the waste plastic cracking furnace is 420-500° C., and the reaction pressure is 8-20 MPa.

5. The method for treating low-quality oil and waste plastics in a slurry bed according to claim 1, characterized in that: In step S2, the weight ratio of waste plastic to liquid phase component is 1:5-10.

6. The method for treating low-quality oil and waste plastics in a slurry bed according to claim 1, characterized in that: When fractionation is performed in step S2, the cutting temperature is 400-420°C, the top temperature of the fractionation tower is 150-180°C, the bottom temperature is 380-420°C, and the top pressure is 0.05-0.2Mpa.

7. The method for treating low-quality oil and waste plastics in a slurry bed according to claim 1, characterized in that: The waste plastics are waste plastics that have been pre-treated by crushing, screening and metal removal.

8. A slurry bed device for treating inferior oil and waste plastics, characterized in that: The invention comprises an inferior oil feeding system, a slurry bed reactor, a hot high-pressure separator, a gas phase product processing system, a waste plastic thermal cracking furnace, a fractionation device, a separation device and a product tank; the inferior oil feeding system comprises a raw material tank, a raw material pump and a heater connected in sequence, the heater discharge port is connected to the slurry bed reactor feed port, the slurry bed reactor discharge port is connected to the hot high-pressure separator feed port, the hot high-pressure separator is provided with a gas phase component pipeline and a liquid phase component pipeline, the gas phase product processing system comprises a buffer tank and an absorption tower, the gas phase component pipeline The line is connected with the buffer tank and the absorption tower in sequence; the liquid component pipeline is connected with the feed port of the waste plastic thermal cracking furnace, and the discharge port of the waste plastic thermal cracking furnace is connected with the fractionation device, and the fractionation device is provided with a light fraction pipeline and a heavy fraction pipeline, and the light fraction pipeline is connected with the product tank, and the heavy fraction pipeline is connected with the feed port of the separation device, and the separation device is provided with a heavy fraction pipeline and a light component pipeline, and the heavy fraction pipeline is connected with the feeding system or directly connected with the slurry bed reactor, and the light component is connected with the product tank.

9. The device for treating inferior oil and waste plastics in a slurry bed according to claim 8, characterized in that: The number of the slurry bed reactors is one or more, and a plurality of slurry bed reactors are arranged in series.

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