A method and apparatus for co-processing inferior oil and waste plastics

Abstract

This invention discloses a method and apparatus for co-processing inferior oil and waste plastics. The co-processing method includes the following steps: S1, inferior oil is mixed with hydrogen, preheated, and then fed into a slurry bed reactor for reaction. The product is separated into gas and liquid phases by a high-pressure thermal separator to obtain gas phase components and liquid phase components. The gas phase components are returned to the slurry bed reactor for further reaction. S2, the liquid phase components obtained in step S1 are mixed with waste plastics and then fed into a low-pressure thermal separator for thermal cracking reaction to obtain gas phase products and liquid phase products. The gas phase products are washed with water and discharged. The liquid phase products are fractionated by a fractionating device to obtain light and heavy fractions. The heavy fraction is separated into a lower layer heavy component and an upper layer light component by a centrifugal separator. The heavy component is recycled to the slurry bed reactor for reaction. The light fraction and light component are the products obtained after processing.

Description

Technical Field

[0001] This invention belongs to the field of petrochemicals, specifically relating to a method and apparatus for the co-processing of inferior oil and waste plastics. Background Technology

[0002] Plastic is one of humanity's major inventions of the 20th century. With the rise of the plastics industry in the mid-20th century, humanity entered the plastics era. The application of plastic products has permeated every corner of society, from industrial production to clothing, food, housing, and transportation; plastic products are ubiquitous. The rapid development of the plastics industry has also brought about a series of social problems caused by discarded and waste plastics, which are undesirable to people. Every year, countries around the world accumulate large amounts of waste plastic, placing enormous environmental pressure on human society.

[0003] Slurry bed hydrocracking is one of the ideal methods to achieve the lightening of heavy oil. The use of 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.

[0004] The amount of waste plastics is increasing year by year, which has seriously affected the safety of my country's atmosphere, soil, and water resources. Traditional methods of treating waste plastics, such as landfill and incineration, bring about environmental problems. Waste plastic pyrolysis technology can turn "waste" into "treasure," with good environmental optimization effects and socio-economic benefits.

[0005] In response to the pain points and difficulties encountered in the utilization or treatment of plastics, there is an urgent need to develop a slurry bed process for the thermal pyrolysis of waste plastics.

[0006] Chinese patent CN101074385A describes a continuous pyrolysis process and equipment for waste plastics. It utilizes a solid heat carrier that mixes with and moves in the same direction as the raw material within the pyrolyzer to heat the material, achieving continuous pyrolysis. The pyrolysis temperature is 380-500℃, and the amount of heat-conducting balls added is approximately 40 times the amount of waste plastic. These heat-conducting balls require continuous recycling and regeneration. The pyrolysis gas needs to undergo secondary pyrolysis, cooling, and fractionation in a fixed bed to obtain gasoline and diesel. The recycling and carbon burning regeneration of a large number of high-temperature heat-conducting balls results in a complex production unit structure, high energy consumption, difficult operation, and a large volume of waste gas and solid waste emissions.

[0007] Patent CN102260515A describes a waste plastic pyrolysis treatment device, in which the reactor contains a low-melting-point metal or salt that can be heated to a molten state. The metal or salt is lead, potassium chloride, sodium chloride, or a mixture thereof; the feeding device presses the waste plastic into the molten metal or salt. Because the density of plastic differs significantly from that of the metal or molten salt, uniform mixing and contact between the two at high temperatures will be difficult.

[0008] Patent CN109355099A discloses a method for co-processing solid waste and coal tar to produce fuel oil. First, the light components of coal tar are treated to extract phenols. Then, the heavy distillate of coal tar is pre-hydrogenated to promote the conversion of gums and asphaltenes in the heavy distillate into partially hydrogenated polycyclic aromatic hydrocarbons, improving the hydrogen supply performance of the heavy distillate. Finally, the liquid products from different distillation ranges in the hydrotreating separator are mixed with solid waste and fed into a co-processing reactor to obtain gasoline, diesel, and phenolic products, thus achieving the co-processing of solid waste and coal. This invention combines the processes of phenol extraction from coal tar, hydrotreating heavy distillates, and co-processing solid waste, providing a large amount of solvent oil with good hydrogen supply performance for the liquefaction of solid waste. It realizes the molecular utilization of coal tar and the large-scale, clean, and efficient utilization of solid waste, significantly improving the conversion efficiency of coal tar and solid waste. It has advantages such as low hydrogen consumption, high oil yield, good economic benefits, and suitability for long-term, large-scale operation of the equipment. However, the process flow is relatively complex. Summary of the Invention

[0009] The purpose of this invention is to provide a method and apparatus for co-processing inferior oil and waste plastics, so as to solve the problems of easy coking in the reaction and the relatively complex structure and process flow of the production equipment in the prior art.

[0010] To achieve the above objectives, the present invention provides a method for co-processing inferior oil and waste plastics, comprising the following steps:

[0011] S1, inferior oil is mixed with hydrogen, preheated and then transported to a slurry bed reactor for reaction. The product is separated into gas phase and liquid phase by a hot high-pressure separator. The gas phase component is returned to the slurry bed reactor to continue the reaction.

[0012] S2, the liquid phase component obtained in step S1 is mixed with waste plastic and then transported to a thermal low-pressure separator for thermal cracking reaction to obtain gaseous and liquid phase products. The gaseous product is washed with water and discharged, while the liquid phase product is fractionated by a fractionating device to obtain light and heavy fractions. The heavy fraction is centrifuged by a centrifugal separator to separate the lower heavy component and the upper light component. The heavy component is recycled to a slurry bed reactor for reaction, while the light fraction and light component are the products obtained after processing.

[0013] The co-treatment method for inferior oil and waste plastics described in this invention uses a slurry bed reactor with a reaction temperature of 440-480℃, a reaction pressure of 8-25MPa, and a liquid hourly space velocity of 0.1-1.2h. -1 The hydrogen-to-oil ratio is 600-1200.

[0014] The co-treatment method for inferior oil and waste plastics described in this invention has a reaction temperature of 440-480℃ and a reaction pressure of 8-20MPa in the thermal high-pressure separator.

[0015] The co-treatment method for inferior oil and waste plastics described in this invention has a reaction temperature of 360-450℃ and a reaction pressure of 4-12MPa in the hot low-pressure separator.

[0016] In the co-treatment method for inferior oil and waste plastics described in this invention, during fractionation in step S2, the cutting temperature is 400-420℃, the top temperature of the fractionation tower is 150-180℃, the bottom temperature is 380-420℃, and the top pressure is 0.05-0.2 MPa.

[0017] In the co-treatment method for inferior oil and waste plastics described in this invention, the weight ratio of waste plastics to liquid phase components in step S2 is 1:5 to 10.

[0018] The method for co-processing inferior oil and waste plastics described in this invention refers to inferior oil as at least one of coal tar, catalytic slurry oil, high-sulfur and high-metal residue oil, atmospheric residue oil, vacuum residue oil, extra-thick heavy crude oil, and oil sands asphalt.

[0019] In the co-treatment method for inferior oil and waste plastics described in this invention, in step S1, an oil-soluble catalyst with hydrogenation function needs to be added during the reaction in the slurry bed reactor. The active component of the oil-soluble catalyst is one or more of Mu, Ni, Co and Fe, and the catalyst concentration is 10-1000 ppm based on metal content.

[0020] The present invention describes a method for co-processing inferior oil and waste plastics, wherein the waste plastics are pre-treated waste plastics that have undergone crushing, screening, and metal removal. The source and type of waste plastics are not specifically limited, and may include one or more of polyethylene (PE), polypropylene (PP), polystyrene (PS), polystyrene foam (PSF), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyurethane (PU), and ABS plastics. To achieve the above objectives, the present invention also provides a co-processing device for inferior oil and waste plastics, comprising an inferior oil feeding system, a slurry bed reactor, a hot high-pressure separator, a waste plastic mixing tank, a hot low-pressure separator, a gas phase product processing system, and a liquid phase product processing system; the inferior oil feeding system includes a raw material tank, a raw material pump, and a heater connected in sequence; the inlet of the slurry bed reactor is connected to the heater, and the outlet is connected to 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 to the inferior oil feeding system or directly to the slurry bed reactor, the liquid phase component pipeline is connected to the inlet of the waste plastic mixing tank, and the outlet of the waste plastic mixing tank is connected to the hot low-pressure separator. The hot low-pressure separator is equipped with a gaseous product pipeline and a liquid product pipeline. The gaseous product processing system includes a buffer tank and a water washing tower. The gaseous product pipeline is connected to the inlet of the buffer tank, and the outlet of the buffer tank is connected to the water washing tower. The liquid product processing system includes a fractionation device, a separation device, and a product tank. The liquid product pipeline is connected to the inlet of the fractionation device. The fractionation device includes a bottom outlet and a top outlet. The top outlet is connected to the product tank, and the bottom outlet is connected to the inlet of the separation device. The separation device includes a heavy component pipeline and a light component pipeline. The heavy component pipeline is connected to the inferior oil feed system or directly to the slurry bed reactor. The light component pipeline is connected to the product tank.

[0021] Beneficial effects of this invention:

[0022] While processing low-quality heavy oil using a slurry bed process, the liquid phase after gas-liquid separation enters a waste plastic mixing tank. After being thoroughly mixed with waste plastic that has undergone crushing, screening, and metal removal pretreatment, it enters a thermal low-pressure separator for further gas-liquid separation. In this separator, the waste plastic undergoes a thorough thermal pyrolysis reaction using the temperature and pressure. The thermal pyrolysis reaction requires high temperature and high pressure. This invention can process waste plastic while saving energy, increasing the yield of liquid products, and achieving the goals of environmental protection and recycling waste plastic resources.

[0023] After the high-pressure separator separates the gas and liquid phases of the material from the reactor, the gas phase is recycled to the slurry bed reactor for further reaction, achieving gas-circulation feeding and reducing the overall energy consumption of the unit. The liquid oil from the fractionation unit is separated into heavy and light fractions by a downstream separation unit. This separation unit effectively extends the operating cycle of the entire unit without clogging, ensuring stable reaction. The heavier oil components are recycled to the slurry bed reactor for continued feeding, while the lighter oil is stored in the product tank or used in subsequent processes, improving oil conversion rate while reducing catalyst consumption. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a co-processing device for inferior oil and waste plastics according to the present invention.

[0025] In the attached figures, the following labels are used:

[0026] 1. Raw material tank; 2. Raw material pump; 3. Heater; 4. Slurry bed reactor; 5. High-pressure thermal separator; 6. Waste plastic mixing tank; 7. Low-pressure thermal separator; 8. Buffer tank; 9. Washing tower; 10. Fractionating device; 11. Separation device; 12. Product tank. Detailed Implementation

[0027] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0028] Figure 1This is a schematic diagram of a co-processing device for inferior oil and waste plastics according to the present invention. It includes a raw material tank 1 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 volumetric plunger pump. The raw material pump 2 is connected to a heater 3, and the heater 3 is connected to a slurry bed reactor 4. An empty-tank slurry bed reactor can be selected to reduce coking and clogging. The slurry bed reactor 4 has an outlet at the top and an inlet at the bottom. The inlet can be a conical feed port to prevent material accumulation, and the outlet can be an arc-shaped side discharge port to ensure smooth discharge. However, this invention does not particularly limit the shape of the inlet and outlet of the slurry bed reactor. In other embodiments, other shapes can be set according to actual production needs. The heater 3 is connected to the bottom inlet of the slurry bed reactor 4, and the top outlet of the slurry bed reactor 4 is connected to a thermal high-pressure separator 5. The thermal high-pressure separator 5 is equipped with gas phase component pipelines and liquid phase component pipelines. The gas phase component pipelines are connected to the raw material pump 2. The separated gas phase components are mixed with inferior oil and then re-enter the slurry bed reactor 4. In another embodiment, the gas phase component pipeline can also be directly connected to the slurry bed reactor 4 as an independent feed system; the liquid phase component pipeline is connected to a waste plastic mixing tank 6, the waste plastic mixing tank 6 is connected to a hot low-pressure separator 7, the hot low-pressure separator 7 is equipped with a gas phase product pipeline and a liquid phase product pipeline, the gas phase product pipeline is connected to a buffer tank 8, the buffer tank 8 is connected to a water washing tower 9, the liquid phase product pipeline is connected to a fractionation device 10, the top of the fractionation device 10 is connected to a product tank 12, and the bottom is connected to a separation device 11, the liquid-solid separation device 11 is equipped with a heavy component pipeline and a light component pipeline, the heavy component pipeline is connected to the raw material pump 2, and the light component pipeline is connected to the product tank 12.

[0029] In this invention, the liquid-solid separation device 11 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 hydrocyclone separator, a flash distillation tower, an atmospheric distillation tower, a vacuum distillation tower, and an extraction tower. Preferably, it is an atmospheric distillation tower.

[0030] The present invention is further illustrated by the following embodiments, but the following embodiments do not limit the scope of protection claimed by the present invention.

[0031] Source of raw materials or equipment: a certain vacuum residue, properties are shown in Table 1.

[0032] Table 1. Properties of vacuum residue

[0033]

[0034]

[0035] Examples 1-3 and Comparative Example 1

[0036] Examples 1-3 employ the following methods: Figure 1 The process flow shown in this embodiment uses molybdenum isooctanoate as the catalyst, with an addition amount of 1000 ppm. The inferior oil containing the catalyst is mixed with hydrogen and then preheated via a feed pump before entering a slurry bed reactor for reaction. After the reaction, the product is separated by a high-pressure thermal separator. The gaseous component enters the hydrogen input pipeline and is then mixed with the inferior oil, returning to the slurry bed reactor for further reaction. The liquid component enters a waste plastic mixing tank and is mixed with waste plastics. It then enters a low-pressure thermal separator for thermal cracking of the waste plastics, simultaneously undergoing gas-liquid separation. The separated gaseous product enters a buffer tank and further enters a water washing tower for washing before being discharged. The separated liquid product is fractionated by a fractionating device to obtain a light distillate from the top of the tower and a heavy distillate from the bottom of the tower. The bottom oil is further separated by a separation device to obtain heavy and light components. The heavy components are mixed with the inferior oil and then re-enter the slurry bed reactor for reaction. The top oil and light components enter a product tank.

[0037] The properties of the feedstock oils used are shown in Table 1, and the process operating conditions are shown in Table 2.

[0038] Table 2. Process conditions for the examples

[0039]

[0040]

[0041] The evaluation results are shown in Table 3:

[0042] Table 3. Evaluation Results of Examples

[0043]

[0044]

[0045] As can be seen from the operation of the embodiment, it has a high conversion rate and liquid product yield, low toluene insoluble content, realizes the resource utilization of waste, and uses the reaction conditions of the hot low-pressure separator to thermally decompose waste plastics, thereby reducing the overall energy consumption of the device.

[0046] Higher reaction pressures generate more activated hydrogen, which can readily combine with macromolecular free radicals to inhibit coking. In a high-pressure reaction system, the equilibrium between hydrogenation and thermal cracking shifts towards hydrogenation. Simultaneously, increased reaction pressure reduces coking on the catalyst, further suppressing coke formation.

[0047] The results from Examples 1, 2, and 3 show that reducing the reaction pressure from 20 MPa to 8 MPa increased the toluene-insoluble content yield from 1.207% to 1.404%, and the reaction apparatus did not become clogged even with higher toluene-insoluble content formation. Furthermore, the conversion rate and liquid product yield increased further with decreasing operating pressure.

[0048] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for co-processing of inferior oil and waste plastic, characterized by, Includes the following steps: S1, inferior oil is mixed with hydrogen, preheated and then transported to a slurry bed reactor for reaction. The product is separated into gas phase and liquid phase by a hot high-pressure separator. The gas phase component is returned to the slurry bed reactor to continue the reaction. S2, the liquid phase component obtained in step S1 is mixed with waste plastic and then transported to a thermal low-pressure separator for thermal cracking reaction to obtain gaseous and liquid phase products. The gaseous product is washed with water and discharged. The liquid phase product is fractionated by a fractionating device to obtain light and heavy fractions. The heavy fraction is separated into lower heavy component and upper light component by a centrifugal separator. The heavy component is recycled to a slurry bed reactor for reaction. The light fraction and light component are the products obtained after treatment. The reaction temperature inside the hot high-pressure separator is 440-480℃, and the reaction pressure is 8-20MPa; The reaction temperature inside the hot low-pressure separator is 360-450℃, and the reaction pressure is 4-12 MPa.

2. The co-processing method of inferior oils and waste plastics according to claim 1, characterized in that, The reaction temperature in the slurry bed reactor is 440-480℃, the reaction pressure is 8-25 MPa, the liquid hourly space velocity is 0.1-1.2 h -1 , and the hydrogen to oil ratio is 600-1200.

3. The co-processing method of inferior oils and waste plastics according to claim 1, characterized in that, During fractionation in step S2, the cutting temperature is 400~420℃, the top temperature of the fractionation column is 150-180℃, the bottom temperature is 380-420℃, and the top pressure is 0.05-0.2MPa.

4. The co-processing method of inferior oils and waste plastics according to claim 1, characterized in that, In step S2, the weight ratio of waste plastic to liquid phase component is 1:5~10.

5. The co-processing method of inferior oils and waste plastics according to claim 1, characterized in that, The waste plastics are waste plastics that have undergone crushing, screening, and metal removal pretreatment.

6. A co-processing device of inferior oil and waste plastic, characterized by, The system includes a low-quality oil feeding system, a slurry bed reactor, a high-pressure thermal separator, a waste plastic mixing tank, a low-pressure thermal separator, a gas phase product processing system, and a liquid phase product processing system. The low-quality oil feeding system comprises a raw material tank, a raw material pump, and a heater connected in sequence. The inlet of the slurry bed reactor is connected to the heater, and the outlet is connected to the high-pressure thermal separator. The high-pressure thermal separator is equipped with gas phase component pipelines and liquid phase component pipelines. The gas phase component pipelines are connected to the low-quality oil feeding system or directly to the slurry bed reactor. The liquid phase component pipelines are connected to the inlet of the waste plastic mixing tank, and the outlet of the waste plastic mixing tank is connected to the low-pressure thermal separator. The low-pressure thermal separator is equipped with gas phase product pipelines and liquid phase product pipelines. The gas phase product processing system includes a buffer tank and a washing tower. The gas phase product pipelines are connected to the inlet of the buffer tank, and the outlet of the buffer tank is connected to the washing tower. The liquid-phase product processing system includes a fractionation unit, a separation unit, and a product tank. The liquid-phase product pipeline is connected to the feed inlet of the fractionation unit. The fractionation unit includes a bottom outlet and a top outlet. The top outlet is connected to the product tank, and the bottom outlet is connected to the feed inlet of the separation unit. The separation unit includes a heavy component pipeline and a light component pipeline. The heavy component pipeline is connected to the inferior oil feed system or directly to the slurry bed reactor, and the light component pipeline is connected to the product tank.

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