Co-treatment method and device for inferior oil and waste plastics

Abstract

The invention discloses a co-treatment method and device for inferior oil and waste plastics, and the co-treatment method comprises the following steps: S1, mixing the inferior oil with hydrogen, preheating, conveying to a slurry bed reactor for reaction, and carrying out gas-liquid separation on the product by a thermal high-pressure separator to obtain a gas-phase component and a liquid-phase component, returning a gas-phase component to the slurry bed reactor for continuous reaction; s2, mixing the liquid-phase component obtained in the step S1 with waste plastics, conveying the mixture into a thermal low-pressure separator for thermal cracking reaction to obtain a gas-phase product and a liquid-phase product, washing the gas-phase product with water, discharging the gas-phase product, fractionating the liquid-phase product through a fractionating device to obtain a light fraction and a heavy fraction, and recycling the light fraction and the heavy fraction; the heavy fraction is separated into lower-layer heavy components and upper-layer light components through a centrifugal separation device, 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 field of petrochemical industry, and particularly relates to a co - processing method and device for inferior oil and waste plastics. 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. From industrial production to clothing, food, housing and transportation, plastic products are everywhere. 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 number of waste plastics accumulate continuously 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 heavy oil upgrading. The use of the heavy oil slurry - bed hydrocracking technology is a currently technically and economically feasible and suitable process technology that 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 landfill and incineration will bring some environmental problems. The waste plastic pyrolysis technology can turn "waste" into "treasure", with 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, there is an urgent need to develop a technology for pyrolyzing waste plastics by the 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 solid heat - carrying bodies that are mixed with the raw materials and move 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, high 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, phenol extraction is carried out on 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, 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 co-processing inferior oil and waste plastics to solve the problems of easy coking in the reaction and the relatively complex structure and process flow of the production device in the prior art.

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

[0011] S1, mixing inferior oil with hydrogen, preheating and then transporting it to a slurry bed reactor for reaction. The product is subjected to gas-liquid separation in a hot high-pressure separator to obtain a gas-phase component and a liquid-phase component. The gas-phase component is returned to the slurry bed reactor for continuous reaction;

[0012] S2, mixing the liquid-phase component obtained in step S1 with waste plastics and then transporting it to a hot low-pressure separator for thermal cracking reaction to obtain a gas-phase product and a liquid-phase product. The gas-phase product is discharged after water washing, and the liquid-phase product is fractionated by a fractionation device to obtain a light fraction and a heavy fraction. The heavy fraction is centrifugally separated by a centrifugal separation device into a lower heavy component and an upper 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 co-processing inferior oil and waste plastics of the present invention, the reaction temperature in the slurry bed reactor is 440 - 480 °C, the reaction pressure is 8 - 25 MPa, the liquid hourly space velocity is 0.1 - 1.2 h -1 , and the hydrogen-oil ratio is 600 - 1200.

[0014] In the method for co-processing inferior oil and waste plastics of 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 co - processing method of inferior oil and waste plastics according to the present invention, the reaction temperature in the thermal low - pressure separator is 360 - 450 °C, and the reaction pressure is 4 - 12 MPa.

[0016] In the co - processing method of inferior oil and waste plastics 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 is 380 - 420 °C, and the top pressure is 0.05 - 0.2 Mpa.

[0017] In the co - processing method of inferior oil and waste plastics according to the present invention, the weight ratio of waste plastics to the liquid - phase component in step S2 is 1:5 - 10.

[0018] In the co - processing method of inferior oil and waste plastics 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 - heavy crude oil, and oil - sand bitumen.

[0019] In the co - processing method of inferior oil and waste plastics according to the present invention, when the reaction is carried out in a slurry - bed reactor in step S1, an oil - soluble catalyst with 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] The co - processing method of inferior oil and waste plastics according to the present invention, wherein the waste plastics are waste plastics after being pretreated by crushing, screening and metal removal. There are no specific limitations on the source and type of 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. To achieve the above - mentioned purpose, the present invention also provides a co - processing device for inferior oil and waste plastics, which includes 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 treatment system and a liquid - phase product treatment system; the inferior oil feeding system includes a raw material tank, a raw material pump and a heater connected in sequence; the feeding port of the slurry bed reactor is communicated with the heater, and the discharging port is communicated with 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 inferior oil feeding system or directly with the slurry bed reactor, the liquid - phase component pipeline is communicated with the feeding port of the waste plastic mixing tank, the discharging port of the waste plastic mixing tank is communicated with the hot low - pressure separator, and the hot low - pressure separator is provided with a gas - phase product pipeline and a liquid - phase product pipeline; the gas - phase product treatment system includes a buffer tank and a water - washing tower, the gas - phase product pipeline is connected with the feeding port of the buffer tank, and the discharging port of the buffer tank is connected with the water - washing tower; the liquid - phase product treatment system includes a fractionation device, a separation device and a product tank, the liquid - phase product pipeline is connected with the feeding port of the fractionation device, the fractionation device includes a bottom discharging port and a top discharging port, the top discharging port is connected with the product tank, the bottom discharging port is connected with the feeding port of the separation device, the separation device includes a heavy - component pipeline and a light - component pipeline, the heavy - component pipeline is communicated with the inferior oil feeding system or directly with the slurry bed reactor, and the light - component pipeline is connected with the product tank.

[0021] Advantages of the present invention:

[0022] While processing inferior heavy oil using the slurry bed process, the liquid phase after gas - liquid separation enters the waste plastic mixing tank, is fully mixed with the waste plastics pretreated by crushing, screening and metal removal, and then enters the hot low - pressure separator for further gas - liquid separation. And in the hot low - pressure separator, the waste plastics are subjected to sufficient thermal cracking reaction by using the temperature and pressure in the hot low - pressure separator. The thermal cracking reaction requires high temperature and high pressure. The present invention can process waste plastics while saving energy consumption, improve the liquid product yield, and achieve the purpose of environmental protection and recycling of waste plastic resources.

[0023] After the high-pressure separator separates the gas and liquid of the materials coming out of the reactor, the gas phase is recycled to the slurry bed reactor for reaction again, realizing gas circulation feeding, which can reduce the overall energy consumption of the device. The liquid-phase oil products coming out of the fractionation unit are separated into heavy fractions and light fractions by a separation device downstream of the fractionation unit. The separation device can effectively extend the operation cycle of the whole device without clogging, enabling the reaction to proceed stably; the heavier component oil is recycled to the slurry bed reactor for continuous feeding, and the light oil products enter the product tank for storage or are used in subsequent processes, which can increase the conversion rate of the oil products while reducing the consumption of the catalyst. Brief Description of the Drawings

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

[0025] Among them, reference numerals:

[0026] 1, raw material tank; 2, raw material pump; 3, heater; 4, slurry bed reactor; 5, hot high-pressure separator; 6, waste plastic mixing tank; 7, hot low-pressure separator; 8, buffer tank; 9, water washing tower; 10, fractionation unit; 11, separation device; 12, product tank. Detailed Embodiments

[0027] The present invention will be specifically described below through examples. It is necessary to point out here that the following examples are only used to further illustrate the present invention and cannot be construed 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.

[0028] Figure 1Schematic diagram of a co - processing device for inferior oil and waste plastics according to the present invention, including a raw material tank 1, 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 heater 3, and the heater 3 is connected to a slurry - bed reactor 4. An empty - barrel type slurry - bed reactor can be selected, which can reduce coking and blockage. The top of the slurry - bed reactor 4 is provided with an outlet, and the bottom of the slurry - bed reactor 4 is provided with an inlet. The inlet can be a conical feed inlet, which can prevent material accumulation. The outlet can be an arc - shaped side discharge outlet, which can ensure smooth discharge. However, the present invention does not particularly limit the forms of the discharge outlet and the feed inlet of the slurry - bed reactor. 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 slurry - bed reactor 4, and the top outlet of the slurry - bed reactor 4 is connected to a hot high - pressure separator 5. The hot 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 the raw material pump 2, and the separated gas - phase components are mixed with inferior oil and then enter the slurry - bed reactor 4 again. 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 provided 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 provided 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 the present invention, the liquid - solid separation device 11 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.

[0030] The present invention will be further illustrated by the following examples, but the following examples do not limit the scope 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 to 3 adopt the process flow shown as Figure 1 follows. The catalyst used in this example is molybdenum isooctanoate, and its addition amount is 1000 ppm. The inferior oil containing the catalyst is mixed with hydrogen and then enters the slurry bed reactor through a raw material pump after preheating for reaction. After the reaction, the product is separated by a hot high-pressure separator. The gas-phase components enter the hydrogen input pipeline and then are mixed with the inferior oil and continue to return to the slurry bed reactor for reaction; the liquid-phase components enter the waste plastic mixing tank to be mixed with waste plastics, and then enter the hot low-pressure separator for thermal cracking reaction of waste plastics and at the same time for gas-liquid separation. The separated gas-phase product enters the buffer tank and further enters the water washing tower for water washing and then is discharged. The separated liquid-phase product is fractionated by a fractionation device to obtain light fraction oil at the top of the tower and heavy fraction oil at the bottom of the tower. The bottom oil of the tower is further separated by a separation device to obtain heavy components and light components. The heavy components are mixed with the inferior oil and then enter the slurry bed reactor for reaction again. The top oil of the tower and the light components enter the product tank.

[0037] The properties of the raw material oil used are shown in Table 1, and the process operating conditions are shown in Table 2:

[0038] Table 2. Process conditions of the examples

[0039]

[0040]

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

[0042] Table 3. Evaluation results of the examples

[0043]

[0044]

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

[0046] A higher reaction pressure will generate more activated hydrogen. The activated hydrogen generated by the activation of the catalyst can timely combine with macromolecular free radicals to inhibit the occurrence of coking reactions. In a high-pressure reaction system, the equilibrium relationship between the hydrogenation reaction and the thermal cracking reaction shifts towards the hydrogenation reaction direction. At the same time, the increase in the reaction pressure can reduce the carbon deposition on the catalyst, further inhibiting the formation of coke.

[0047] From the results of Examples 1, 2 and 3, it can be concluded that when the reaction pressure is reduced from 20 MPa to 8 MPa, the yield of toluene-insoluble matter increases from 1.207% to 1.404%, and the reaction device does not become blocked even when a relatively high amount of toluene-insoluble matter is generated. When the operating pressure is reduced, the conversion rate and the yield of liquid products also increase further.

[0048] Of course, the present invention may 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 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 low-quality oil and waste plastics, 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 is separated into gas and liquid by a hot high-pressure separator to obtain a gas phase component and a liquid phase component, and 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 the waste plastic and then transported to a hot low-pressure separator for thermal cracking reaction to obtain a gas phase product and a liquid phase product. The gas phase product is discharged after washing with water, and the liquid phase product is fractionated by a fractionation device to obtain a light fraction and a heavy fraction. The heavy fraction is separated into a lower layer heavy component and an upper layer light component by a centrifugal separation device, and the heavy component is circulated to the slurry bed reactor for reaction. The light fraction and the light component are the products obtained after treatment.

2. The method for co-processing low-quality oil and waste plastics according to claim 1, characterized in that: The reaction temperature in the slurry bed reactor is 440-480°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 600-1200.

3. The method for co-processing low-quality oil and waste plastics 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 co-processing low-quality oil and waste plastics according to claim 1, characterized in that: The reaction temperature in the hot low-pressure separator is 360-450° C., and the reaction pressure is 4-12 MPa.

5. The method for co-processing low-quality oil and waste plastics 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.

6. The method for co-processing low-quality oil 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.

7. The method for co-processing low-quality oil and waste plastics 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 co-processing device for inferior oil and waste plastics, characterized in that: It comprises 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 comprises a raw material tank, a raw material pump and a heater which are connected in sequence; the feed port of the slurry bed reactor is connected to the heater, and the discharge port 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 connected to the slurry bed reactor, the liquid phase component pipeline is connected to the feed port of the waste plastic mixing tank, the discharge port of the waste plastic mixing tank is connected to the hot low-pressure separator, and the hot low-pressure separator is provided with a gas phase product pipeline and a liquid phase product pipeline; the gas phase product processing system comprises a buffer tank and a water washing tower, the gas phase product pipeline is connected to the feed port of the buffer tank, and the discharge port 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 feed port of the fractionation device, the fractionation device includes a bottom discharge port and a top discharge port, the top discharge port is connected to the product tank, the bottom discharge port is connected to the feed port of the separation device, the separation device includes a recombinant component pipeline and a light component pipeline, the recombinant component pipeline is connected to the inferior oil feed system or directly connected to the slurry bed reactor, and the light component pipeline is connected to the product tank.

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