Method and device for hydroprocessing waste plastics in poor-quality slurry oil reactor

Abstract

The invention discloses a method and a device for hydroprocessing waste plastics by using an inferior oil slurry reactor, and the method comprises the following steps: S1, mixing inferior oil with hydrogen, preheating, conveying to a slurry reactor for reaction, and carrying out gas-liquid separation on the product by using a thermal high-pressure separator to obtain a gas-phase component and a liquid-phase component; s2, mixing the gas-phase component with the waste plastic, performing thermal cracking on the waste plastic by utilizing gas-phase waste heat, washing a gas-phase product in thermal cracking products, collecting and discharging the gas-phase product, mixing a liquid-phase product with the liquid-phase component in the step S1, and performing fractionation in a fractionation device to obtain a light fraction and a heavy fraction, the heavy fraction is separated again through a centrifugal separation device to obtain lower-layer heavy components and upper-layer light components, the heavy components are circulated to the slurry bed reactor for reaction, and the light fraction and the light components are products obtained after treatment.

Description

Technical Field

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

[0002] Plastics are one of the major inventions of mankind since the 20th century. With the rise of the plastics industry in the mid-20th century, humanity has entered the plastic era. The application of plastic products has penetrated every corner of society. Plastics are everywhere, from industrial production to clothing, food, shelter, and transportation. The rapid development of the plastics 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 sources, 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 problems 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 the addition amount of the waste plastics. 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, great operation difficulty, 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-point metals or salts that can be heated to a molten state. The metals or salts are lead or potassium chloride, sodium chloride, or their mixed salts; the feeding device presses the waste plastics into the molten metal or molten salt. Since the density of plastics is quite different from that of metals or molten salts, 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 phenol is extracted from the light components of coal tar; then, the heavy distillate oil of coal tar is pre-hydrogenated to promote the conversion of resins and asphaltenes in the heavy distillate oil into partially hydrogenated polycyclic aromatic hydrocarbons, improving the hydrogen supply performance of the heavy distillate 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. The invention combines the processes of phenol extraction from coal tar, hydrogenation of heavy distillate, 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 object of the present invention is to provide a method and device for hydroprocessing waste plastics in a slurry bed with inferior oil, so as to solve the problems of easy coking in the reaction and the complexity of the used device and process flow in the prior art.

[0010] To achieve the above object, the present invention provides a method for hydroprocessing waste plastics in a slurry bed with inferior oil, comprising the following steps:

[0011] S1, mixing inferior oil with hydrogen, preheating and then transporting it to a slurry bed reactor for reaction, and separating the product through a hot high-pressure separator to obtain a gas-phase component and a liquid-phase component;

[0012] S2, mixing the gas-phase component with waste plastics and using the waste heat of the gas phase to pyrolyze the waste plastics. The gas-phase products in the pyrolysis products are collected and discharged after being washed with water, and the liquid-phase products are mixed with the liquid-phase component in step S1 and fractionated in a fractionation device to obtain a light fraction and a heavy fraction. The heavy fraction is separated again through a centrifugal separation device to obtain a lower-layer heavy component and an upper-layer 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 hydroprocessing waste plastics in a slurry bed with inferior oil according to the present invention, the reaction temperature in the slurry bed reactor is 440 - 480 °C, the reaction pressure is 8 - 20 MPa, the liquid hourly space velocity is 0.3 - 1.0 h -1 , and the hydrogen-oil ratio is 600 - 1000.

[0014] In the method for hydroprocessing waste plastics in a slurry bed with inferior oil 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] In the method for hydroprocessing waste plastics in a poor-quality oil slurry bed according to the present invention, in step S2, the pyrolysis reaction temperature is 420 - 500 °C, and the reaction pressure is 8 - 20 MPa.

[0016] In the method for hydroprocessing waste plastics in a poor-quality oil slurry bed according to the present invention, in step S2, the mass ratio of the waste plastics to the gas-phase components added in the pyrolysis reaction is between 1:5 and 1:10.

[0017] In the method for hydroprocessing waste plastics in a poor-quality oil slurry bed according to the present invention, when fractionation is carried out in step S2, the cutting temperature is 400 - 420 °C, the top temperature of the fractionation tower is 150 - 180 °C, the bottom temperature of the tower is 380 - 420 °C, and the top pressure of the tower is 0.05 - 0.2 Mpa.

[0018] In the method for hydroprocessing waste plastics in a poor-quality oil slurry bed according to the present invention, the poor-quality oil is at least one of coal tar, catalytic oil slurry, high-sulfur and high-metal residue oil, atmospheric residue, vacuum residue, extra-heavy crude oil, and oil sand asphalt.

[0019] In the method for hydroprocessing waste plastics in a poor-quality oil slurry bed according to the present invention, when the reaction is carried out 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] In the method for hydroprocessing waste plastics in a poor-quality oil slurry bed according to the present invention, the waste plastics are waste plastics pretreated by crushing, screening, and metal removal. The source and type of the waste plastics are not specifically limited. 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 hydroprocessing waste plastics in a slurry bed using inferior oil, which includes an inferior oil feeding system, a slurry bed reactor, a hot high-pressure separator, a waste plastic pyrolysis furnace, a gas-liquid separation device, 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 preheater connected in sequence, the feeding port of the slurry bed reactor is communicated with the discharging port of the preheater, the discharging port of the slurry bed reactor is communicated with the feeding port 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 component pipeline is communicated with the feeding port of the waste plastic pyrolysis furnace, the discharging port of the waste plastic pyrolysis furnace is communicated with the feeding port of the gas-liquid separation device, the gas-liquid separation device is provided with a gas pipeline and a liquid pipeline, the liquid pipeline is communicated with the feeding port of the fractionation device, the feeding port of the fractionation device is also communicated with the liquid-phase component pipeline, the fractionation device includes a top discharging port and a bottom discharging port, the top discharging port is connected to the product tank, the bottom discharging port is communicated with the separation device, the separation device is provided with a heavy fraction pipeline and a light fraction pipeline, the heavy fraction pipeline is communicated with the inferior oil feeding system or directly communicated with the slurry bed reactor, and the light fraction pipeline is connected to the product tank.

[0022] Advantages of the present invention:

[0023] 1. While using the slurry bed process to process inferior heavy oil, the waste plastics are pyrolyzed using the waste heat of the gas phase separated by the hot high-pressure separator. The pyrolysis reaction requires high temperature and high pressure, and the present invention can process waste plastics while saving energy consumption, improve the liquid product yield, and achieve environmental protection and the purpose of recycling waste plastic resources.

[0024] 2. A gas-liquid separation device and a fractionation device are arranged after the waste plastic pyrolysis furnace to fractionate the oil after pyrolysis and the liquid-phase oil separated from the hot high-pressure separator. Through the separation device downstream of the fractionation device, 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, which can improve the oil conversion rate while reducing the consumption of the catalyst. At the same time, the separation device can effectively extend the operation cycle of the device without clogging and make the reaction proceed stably. Description of the Drawings

[0025] Figure 1 It is a schematic structural diagram of the device for hydroprocessing waste plastics in a slurry bed using inferior oil of the present invention.

[0026] Wherein, reference numerals:

[0027] 1. Raw material tank; 2. Raw material pump; 3. Preheater; 4. Slurry bed reactor; 5. Thermal high-pressure separator; 6. Waste plastic pyrolysis furnace; 7. Gas-liquid separation device; 8. Fractionation device; 9. Separation device; 10. Product tank. Detailed implementation mode

[0028] 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.

[0029] Please refer to Figure 1 , a device for hydroprocessing waste plastics with inferior slurry oil in a slurry bed provided by the present invention, includes a raw material tank 1, the raw material tank 1 is connected to a raw material pump 2, and the raw material pump 2 is used to input the materials in the raw material tank 1 into the slurry bed reactor 4. The present invention does not particularly limit the types of the raw material tank 1 and the raw material pump 2, and 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, the preheater 3 is connected to a slurry bed reactor 4, the top of the slurry bed reactor 4 is provided with a discharge port, and the discharge port can be an arc-shaped side discharge port to ensure smooth discharge; the bottom of the slurry bed reactor 4 is provided with a feed port, and the feed port can be a conical feed port to prevent material accumulation, but the present invention does not particularly limit the forms of the discharge port and the feed port of the slurry bed reactor. In other embodiments, they can be set to other forms according to actual production needs. The preheater 3 is connected to the bottom feed port of the slurry bed reactor 4. The present invention preferably uses an empty-barrel type slurry bed reactor, which can reduce coking and blockage. The discharge port of the slurry bed reactor 4 is connected to a thermal high-pressure separator 5, the thermal high-pressure separator 5 is provided with a gas-phase component pipeline and a liquid-phase component pipeline, the gas-phase component pipeline is connected to a waste plastic pyrolysis furnace 6, the waste plastic pyrolysis furnace 6 is connected to a gas-liquid separation device 7, the gas-liquid separation device 7 is provided with a gas-phase pipeline and a liquid-phase pipeline, the liquid-phase pipeline is connected to a fractionation device 8, the fractionation device 8 is also connected to the thermal high-pressure separator 5 through a liquid-phase component pipeline, the fractionation device 8 includes a top discharge port and a bottom discharge port, the top discharge port is connected to a product tank 10, the bottom discharge port is connected to a separator 9, the separator 9 is provided with a heavy component pipeline and a light component pipeline, the heavy component pipeline is connected to the raw material pump 2, and after being mixed with inferior oil, it enters the slurry bed reactor 4 again. In another embodiment, the heavy fraction pipeline can also be used as an independent feed system and directly connected to the slurry bed reactor 4; the light component pipeline is connected to a product tank 10.

[0030] The separator 9 can be a combination of one or more 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 cyclone separator, a flash tower, an atmospheric distillation column, a vacuum distillation column, an extraction column, etc. Preferably, the device in the present invention is a hot high-pressure separation tank.

[0031] The fractionation device 8 can be a combination of one or more 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 cyclone separator, a flash tower, an atmospheric distillation column, a vacuum distillation column, an extraction column, etc. Preferably, the device in the present invention is an atmospheric distillation column.

[0032] The present invention will be further described below by way of examples, but the following examples do not limit the scope claimed by the present invention.

[0033] Examples 1 - 3

[0034] Examples 1 - 3 adopt the process flow as Figure 1 shown. After hydrogen and the raw material are preheated in the preheater 3, they are input into the slurry bed reactor 4 for reaction. The obtained product undergoes gas-liquid separation in the hot high-pressure separator 5. The liquid phase after gas-liquid separation enters the fractionation device 8, and the gas phase after gas-liquid separation enters the waste plastic pyrolysis furnace 6 to utilize the waste heat of the gas phase for pyrolysis reaction with the waste plastic (adding waste plastic in a certain proportion to the gas phase material) that has undergone crushing, screening, and metal removal pretreatment. After the reaction, it enters the gas-liquid separation device 7. The gas phase after the pyrolysis reaction can be discharged or collected for subsequent processes after being washed with water in the gas-liquid separation unit. The liquid phase oil product after the reaction enters the fractionation device 8. The liquid phase coming out of the hot high-pressure separator 5 and the liquid phase coming out of the gas-liquid separation device 7 are fractionated by the fractionation device 8. The light fraction obtained by fractionation enters the product tank 10, and the heavy fraction passes through the separation device 9 and is divided into two streams of materials. The light oil product enters the product tank 10 for storage or for subsequent processes, and the heavier oil product is recycled to the feed unit to form the reaction feed with the fresh raw material.

[0035] The properties of the raw material oil used are shown in Table 1, and the process operating conditions are shown in Table 2:

[0036] Table 1. Properties of vacuum residue

[0037]

[0038]

[0039] Table 2. Process conditions of the examples

[0040]

[0041]

[0042] Table 3. Evaluation results of the examples

[0043]

[0044]

[0045] It can be seen from the operation of the embodiments 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, reduces the overall energy consumption of the device by using gas-phase waste heat cracking, and as the pressure decreases, the conversion rate and the liquid product yield further increase.

[0046] 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 hydrogenating waste plastics using a low-quality oil 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, and separating the product into gas and liquid components through a hot high-pressure separator; S2, the gaseous component is mixed with the waste plastics and the waste plastics are thermally cracked by utilizing the waste heat of the gas phase. The gaseous product in the thermal cracking product is washed with water and then collected and discharged. The liquid product is mixed with the liquid component in step S1 and fractionated in a fractionating device to obtain a light fraction and a heavy fraction. The heavy fraction is separated again by a centrifugal separation device to obtain a lower layer heavy component and an upper layer light component. The heavy component is circulated to the slurry bed reactor for reaction, and the light fraction and the light component are the products obtained after treatment.

2. The method for hydrogenating waste plastics using a low-quality oil slurry bed according to claim 1, characterized in that: The reaction temperature in the slurry bed reactor is 440-480°C, the reaction pressure is 8-20MPa, and the liquid hourly space velocity is 0.3-1.0h -1 , the hydrogen-to-oil ratio is 600-1000.

3. The method for hydrogenating waste plastics using a low-quality oil 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 hydrogenating waste plastics using a low-quality oil slurry bed according to claim 1, characterized in that: In step S2, the thermal cracking reaction temperature is 420-500°C, and the reaction pressure is 8-20MPa.

5. The method for hydrogenating waste plastics using a low-quality oil slurry bed according to claim 1, characterized in that: In step S2, the mass ratio of waste plastics to gas phase components added to the thermal cracking reaction is between 1:5 and 1:

10.

6. The method for hydrogenating waste plastics using a low-quality oil 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 hydrogenating waste plastics using a low-quality oil 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 device for hydrogenating waste plastics in a low-quality oil slurry bed, characterized in that: The invention comprises an inferior oil feeding system, a slurry bed reactor, a hot high-pressure separator, a waste plastic thermal cracking furnace, a gas-liquid separation device, 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 preheater which are connected in sequence, the feeding port of the slurry bed reactor is connected with the discharging port of the preheater, the discharging port of the slurry bed reactor is connected with the feeding port 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 component pipeline is connected with the feeding port of the waste plastic thermal cracking furnace, the discharging port of the waste plastic thermal cracking furnace is connected with the gas phase component pipeline, and the gas phase component pipeline is connected with the feeding port of the waste plastic thermal cracking furnace. The feed port of the fractionation device is connected, the gas-liquid separation device is provided with a gas phase pipeline and a liquid phase pipeline, the liquid phase pipeline is connected with the feed port of the fractionation device, the feed port of the fractionation device is also connected with the liquid phase component pipeline, the fractionation device comprises a top discharge port and a bottom discharge port, the top discharge port is connected with the product tank, the bottom discharge port is connected with the separation device, the separation device is provided with a heavy component pipeline and a light component pipeline, the heavy fraction pipeline is connected with the inferior oil feed system or directly connected with the slurry bed reactor, and the light fraction pipeline is connected with the product tank.

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