Waste plastic and petroleum mixed feeding catalytic cracking process

Abstract

A waste plastic and petroleum mixed feeding catalytic cracking process comprises a waste plastic self-hot melting dechlorination pretreatment process, a waste plastic molten liquid and petroleum catalytic cracking process and a cracked oil gas fractionation process. Part of recycle oil and cracking dry gas in the cracking oil-gas fractionation sub-process are cyclically returned to the waste plastic self-heating melting dechlorination pretreatment process to serve as high-temperature melting oil and feeding carrying gas, and waste plastic melting liquid in the waste plastic self-heating melting dechlorination pretreatment process is sent out to be mixed with crude oil to serve as a raw material for catalytic cracking of the waste plastic melting liquid and the crude oil; the oil gas is produced to the maximum extent through efficient dispersion atomization feeding and catalytic cracking of an atomizing nozzle, and then the cracked oil gas is subjected to fractionation to produce gasoline, diesel oil, recycle oil and cracked dry gas.

Description

1. Technical Field

[0001] The invention provides a catalytic cracking process of mixed feed of waste plastics and petroleum, belonging to the field of energy chemical industry. 2. Background technology

[0002] While the widespread use of plastics has brought great convenience to people's lives, it has also brought a lot of white pollution. The use cycle of plastics is very short. A large number of plastic products, especially packaging materials, are discarded after about 6-12 months. 40% of plastics are discarded after 1-2 years. The total annual output of plastic waste in the world has reached 50 million tons. In the past few decades, waste plastics have been regarded as part of municipal solid waste (MSW). According to surveys, waste plastics account for 4%-10% (wt) or 10%-20% (v%) in MSW in industrially developed countries, mainly from packaging waste, automobile garbage and processing waste. The percentages of various types of waste plastics are: low-density polyethylene (LDPE) 27%; high-density polyethylene (HDPE) 21%; polypropylene (PP) 18%; polystyrene (PS) 16%; polyvinyl chloride (PVC) 7%. Due to the lack of efficient, clean and large-scale technology, waste plastics have become an environmental problem that needs to be solved in the world.

[0003] In the treatment of urban plastic solid waste, landfill, incineration and recycling are the three main methods. Due to different national conditions, the methods vary from country to country. The United States mainly uses landfill, while Europe and Japan mainly use incineration. At present, rapid pyrolysis / catalytic pyrolysis liquefaction or chemical production of waste plastics has become a hot topic at home and abroad, and is also the waste plastic treatment technology with the most promising industrialization prospects.

[0004] Rapid pyrolysis / catalytic pyrolysis of waste plastics is an effective recycling method that heats waste plastics at high temperatures under oxygen-free or low-oxygen conditions to decompose them and produce valuable products, such as the pyrolysis and liquefaction of waste plastics to produce gasoline, diesel, petroleum wax and other chemical raw materials. However, due to the characteristics of waste plastics such as large size and light weight, difficulty in compression, airtightness, easy expansion, easy melting and bonding, and poor thermal conductivity, it is difficult to solve the problem of continuous feeding and rapid heating. At present, most of the pyrolysis and liquefaction of waste plastics adopt reactor-type intermittent reactions and horizontal rotary kiln reactions, which have slow heating rates, serious feed adhesion and coking, low liquid product yields and added value, and difficult to improve processing capacity. It is difficult to scale up the pyrolysis device, and the subsequent processing of chlorine-containing liquid products is difficult, which restricts the efficient, clean and large-scale utilization of waste plastics. At present, there is no large-scale commercial waste plastic pyrolysis device.

[0005] Catalytic cracking is the main technology for petroleum processing and the main device for producing gasoline, diesel and propylene. It has a short process, simple operation, low cost and energy consumption, and low investment. Combining rapid pyrolysis / catalytic pyrolysis of waste plastics with catalytic cracking of petroleum is an effective means to improve the clean and efficient utilization of waste plastics as raw materials, reduce the consumption of petroleum resources, solve the problem of pyrolysis feed of waste plastics, and improve the yield of gasoline and diesel and the economic benefits of the device. It is urgent to develop catalytic cracking technology and equipment technology for mixed feed of waste plastics and petroleum. 3. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the existing waste plastic pyrolysis liquefaction technology and provide a catalytic cracking process for mixed feed of waste plastic and petroleum, utilize pyrolysis dry gas and high-temperature recycled oil circulation to carry out hot melt dechlorination and sulfur removal pretreatment of waste plastic and liquid phase atomization feeding, solve the difficult problems of pyrolysis feeding and removal of chlorine and sulfur heteroatoms; adopt catalytic cracking to treat mixed raw materials of waste plastic and crude oil, the cracking characteristics complement each other, inhibit condensation coking, eliminate the amplification effect, realize controllable cracking of waste plastic, maximize the production of triolefins and triphenyls, solve the five common problems of waste plastic feed adhesion and coking, difficulty in mixing with heat carrier, low yield and added value of liquid product, difficulty in removing chlorine and sulfur heteroatoms of liquid product thus affecting subsequent processing, and difficulty in amplifying pyrolysis equipment, and realize efficient, clean and high-value large-scale utilization of waste plastic and crude oil.

[0007] The technical solution of the present invention:

[0008] In the catalytic cracking process of mixed feed of waste plastic and petroleum, the clean PE, PP and PS waste plastics are sorted through the waste plastic crusher, and the waste plastic fragments are added to the water-cooled feed pipe of 20-95℃ through the controllable feeder, and fall into the 240-320℃ recycled oil melt liquid of the hot melt dechlorination reactor with stirring under the support of the cracking dry gas, and the melt dechlorination and desulfurization pretreatment is carried out by stirring and mixing. The molten plastic liquid extracted from the bottom of the hot melt dechlorination reactor is pressurized and transported by a delivery pump. A part of it is heated to 20-60℃ higher than the temperature of the recycled oil melt liquid through a high-speed circulation pipe with external heating and then returned to the upper part of the hot melt dechlorination reactor, and the other part is sent to the upper part of the cracking reactor together with the petroleum as a raw material through the atomizing feed nozzle. The gas extracted from the top of the hot melt dechlorination reactor is treated by the desulfurization and dechlorination reactor and then enters the refinery dry gas network as fuel gas. The flow rate of the high-speed circulation pipe is 2-30m / s, and the circulation of the molten plastic liquid is consistent with the original The material ratio is 1-10:1, and the steam dosage of the atomizing feed nozzle is 4%-12% of the raw material amount; the atomized particle feed of the mixture of molten plastic liquid and petroleum is quickly mixed, vaporized and cracked with the cracking regeneration catalyst falling from the top of the cracking reactor, the steam dosage of the atomizing feed nozzle is 4%-12% of the raw material amount, the cracking reaction temperature is 500-550°C, the pressure is 0-0.3MPa, the reaction time is 600 milliseconds-2 seconds, and oil-gas gas-solid separation is performed at the bottom of the cracking reactor; the separated catalyst to be regenerated flows into the bottom of the regeneration reactor through a return device and is regenerated by air fluidization burning at 500-750°C. The bottom of the regeneration reactor is provided with a regeneration air inlet, and the top is provided with a gas-solid separator, a heat exchanger and a regeneration flue gas outlet in sequence. The regenerated catalyst separated by the gas-solid separator at the top of the regeneration reactor is circulated back to the top of the cracking reactor through a return controller to catalytically crack the mixture of molten plastic liquid and petroleum. The high-temperature cracked oil and gas enter the distillation tower for separation. The cracked dry gas at the top of the distillation tower is circulated back to the water-cooled feed pipe at the top of the hot melt dechlorination reactor as feed carrying gas, and is sent to the cracked dry gas absorption and desorption system to produce liquefied gas. The recycled oil is circulated back to the top of the hot melt dechlorination reactor as high-temperature melting oil, and is sent to the product after recovering the waste heat. The other side lines of the distillation tower are liquefied gas, gasoline fraction and diesel fraction.

[0009] The outer wall of the water-cooled feed pipe is provided with a water-cooling jacket, which is in the shape of a positive cone, a straight tube or an inverted cone, preferably a positive cone.

[0010] The controllable feeder is a rotary feeder, a double-shaft screw feeder or a single-shaft screw feeder.

[0011] The high-speed circulation tube is heated by electromagnetic induction heating, thermal oil heating, steam heating or resistance heating, preferably electromagnetic induction heating.

[0012] The catalytic cracking reactor is a riser reactor or a downer reactor.

[0013] The cracking catalyst is a mixture of one or more of an FCC molecular sieve catalyst, a ZSM-5 selective molecular sieve catalyst, and an alkaline solid porous catalyst.

[0014] The present invention will be described in detail with reference to embodiments. 4. Description of the drawings

[0015] Attached Figure 1 The figure is a schematic flow chart of the catalytic cracking process of the present invention using mixed feed of waste plastics and petroleum.

[0016] Attached Figure 1 The drawing settings are as follows:

[0017] 1. Gas-solid separator, 2. Feed return controller, 3. Atomizing feed nozzle, 4. Cracking reactor, 5. Oil-gas gas-solid separator, 6. Fractionation tower, 7. Feed return, 8. Refinery pump, 9. Regeneration air inlet, 10. Regeneration reactor, 11. Heat exchanger, 12. Regeneration flue gas outlet, 13. Diesel fraction, 14. Gasoline fraction, 15. Waste plastic crusher, 16. Controllable feeder, 17. Water-cooled feed pipe, 18. Hot melt dechlorination reactor, 19. Delivery pump, 20. Desulfurization and dechlorination reactor, 21. Refinery dry gas pipeline network, 22. High-speed circulation pipe, 23. Petroleum feed line, 24. Liquefied gas

[0018] The process characteristics of the present invention are described in detail below in conjunction with the accompanying drawings and embodiments. 5. Specific implementation methods

[0019] The present invention provides a catalytic cracking process for mixed feed of waste plastics and petroleum. The clean PE, PP and PS waste plastics separated are fed into a water-cooled feed pipe (17) at 20-95°C through a waste plastic crusher (15). The waste plastic fragments are fed into a water-cooled feed pipe (17) at 20-95°C through a controllable feeder (16). The waste plastic fragments are carried by cracked dry gas and fall into a 240-320°C oil slurry melt in a hot melt dechlorination reactor (18) with stirring. The melt dechlorination and desulfurization pretreatment is performed by stirring and mixing. The molten plastic liquid extracted from the bottom of the hot melt dechlorination reactor (18) is fed into a conveying pump (19). The fuel gas is transported by pressure, one part is heated to a temperature 20-60°C higher than the temperature of the recycled oil melt through a high-speed circulation pipe (22) with external heating, and then returns to the upper part of the hot melt dechlorination reactor (18), and the other part is sent to the upper part of the cracking reactor (4) together with the petroleum as a raw material through an atomizing feed nozzle (3). The fuel gas extracted from the top of the hot melt dechlorination reactor (18) is treated by a desulfurization and dechlorination reactor (20) and then enters the refinery dry gas network (21) as fuel gas. The flow rate of the high-speed circulation pipe (22) is 2-30 m / s. The circulation of the molten plastic liquid The ratio of the ring to the raw material is 1 to 10:1, and the amount of steam used in the atomizing feed nozzle (3) is 4% to 12% of the amount of the raw material; the atomized particle feed of the mixture of the molten plastic liquid and the petroleum is quickly mixed, vaporized and cracked with the cracking regeneration catalyst dropped from the top of the cracking reactor (4), the amount of steam used in the atomizing feed nozzle (3) is 4% to 12% of the amount of the raw material, the cracking reaction temperature is 500 to 550°C, the pressure is 0-0.3MPa, the reaction time is 600 milliseconds to 2 seconds, and oil-gas-solid reaction is carried out at the bottom of the cracking reactor (4). Separation (5); the separated catalyst to be regenerated flows into the bottom of the regeneration reactor (10) through the return device (7) and is regenerated by air fluidization charring at 500-750°C. The regeneration reactor (10) is provided with a regeneration air inlet (9) at the bottom, and a gas-solid separator (1), a heat exchanger (11) and a regeneration flue gas outlet (12) at the top. The regenerated catalyst separated by the gas-solid separator (1) at the top of the regeneration reactor (10) is circulated back to the top of the cracking reactor (4) through the return controller (2) to catalytically crack the mixture of molten plastic liquid and petroleum. The high-temperature cracked oil and gas enter the fractionation tower (6) for separation. One of the cracked dry gas pipelines at the top of the fractionation tower (6) is connected to the feed carrying gas inlet of the water-cooled feed pipe (17) at the top of the hot melt dechlorination reactor (18), and the other is connected to the refinery dry gas pipeline network (21). One of the oil return pipelines of the fractionation tower (6) is connected to the high-temperature dissolved oil inlet at the top of the hot melt dechlorination reactor (18), and the other is sent out as a product after recovering the waste heat. Other side lines of the fractionation tower (6) are liquefied gas, gasoline fraction and diesel fraction.

[0020] The outer wall of the water-cooled feed pipe (17) is provided with a water-cooled jacket, which is in the shape of a positive cone, a straight tube or an inverted cone, preferably a positive cone.

[0021] The controllable feeder (16) is a rotary feeder, a double-shaft screw feeder or a single-shaft screw feeder.

[0022] The high-speed circulation pipe (22) is heated by electromagnetic induction heating, heat-conducting oil heating, steam heating or resistance heating, preferably electromagnetic induction heating.

[0023] The cracking reactor (4) is a riser reactor or a downer reactor.

[0024] The cracking catalyst is a mixture of one or more of an FCC molecular sieve catalyst, a ZSM-5 selective molecular sieve catalyst, and an alkaline solid porous catalyst.

[0025] The catalytic cracking process of mixed feed of waste plastics and petroleum can continuously, on a large scale, efficiently and cleanly utilize waste plastics and crude oil for catalytic cracking to produce gasoline and diesel. It has solved five common industry problems: adhesion and coking of waste plastic feed, difficulty in mixing with high-temperature catalysts, low yield and added value of liquid products, difficulty in scale-up of pyrolysis equipment, and difficulty in subsequent processing of liquid products containing chlorine. The yield of liquefied gas is ≥16%, the yield of gasoline is ≥42%, the yield of diesel is ≥36%, and the total yield of liquid products is above 94%, which is more than 24 percentage points higher than that of traditional waste plastic pyrolysis technology, realizing safe, stable, full and optimal operation of the device.

Claims

1. A catalytic cracking process for mixed feed of waste plastics and petroleum, wherein the clean PE, PP and PS waste plastics are sorted and added into a water-cooled feed pipe at 20-95°C through a waste plastic crusher and waste plastic fragments through a controllable feeder, and fall into a 240-320°C recycled oil melt liquid in a hot melt dechlorination reactor with stirring under the support of cracking dry gas, and melt dechlorination and desulfurization pretreatment is performed by stirring and mixing, and the molten plastic liquid extracted from the bottom of the hot melt dechlorination reactor is conveyed under pressure by a conveying pump, and a part of it is heated to a temperature higher than that of the recycled oil melt liquid through a high-speed circulation pipe with external heating. After the temperature is increased by 20-60°C, it returns to the upper part of the hot melt dechlorination reactor, and the other part is sent to the upper part of the cracking reactor together with petroleum as raw materials through the atomizing feed nozzle. The gas extracted from the top of the hot melt dechlorination reactor is treated by the desulfurization and dechlorination reactor and then enters the refinery dry gas network as fuel gas. The flow rate of the high-speed circulation pipe is 2-30m / s, the circulation ratio of the molten plastic liquid to the raw material is 1-10:1, and the steam consumption of the atomizing feed nozzle is 4wt%-12wt% of the raw material amount; the atomized particle feeding of the mixture of the molten plastic liquid and petroleum falls from the top of the cracking reactor. The cracking regeneration catalyst undergoes rapid mixing, vaporization and cracking reaction, the steam dosage of the atomizing feed nozzle is 4wt% to 12wt% of the raw material amount, the cracking reaction temperature is 500 to 550°C, the pressure is 0-0.3MPa, the reaction time is 600 milliseconds to 2 seconds, and oil and gas are separated at the bottom of the cracking reactor; the separated catalyst to be regenerated flows into the bottom of the regeneration reactor through a return feeder and is regenerated by air fluidization burning at 500-750°C. The regeneration reactor is provided with a regeneration air inlet at the bottom, and a gas-solid separator, a heat exchanger and a regeneration flue gas outlet are provided at the top in sequence. The regenerated catalyst separated by the gas-solid separator at the top of the regeneration reactor is circulated back to the top of the cracking reactor through the return controller to catalytically crack the mixture of molten plastic liquid and petroleum; the high-temperature cracked oil and gas enter the distillation tower for separation, and the cracked dry gas at the top of the distillation tower is circulated back to the water-cooled feed pipe at the top of the hot melt dechlorination reactor as feed carrying gas in one way and sent to the cracked dry gas absorption and desorption system to produce liquefied gas in another way. The recycled oil is circulated back to the upper part of the hot melt dechlorination reactor as high-temperature molten oil in one way and sent as a product after recovering the waste heat in another way. The other side lines of the distillation tower are liquefied gas, gasoline fraction and diesel fraction.

2. The catalytic cracking process of waste plastics and petroleum mixed feed according to claim 1, characterized in that The outer wall of the water-cooled feed pipe is provided with a water-cooling jacket, which is in the shape of a positive cone, a straight tube or an inverted cone, preferably a positive cone.

3. The catalytic cracking process of waste plastics and petroleum mixed feed according to claim 1, characterized in that The controllable feeder is a rotary feeder, a double-shaft screw feeder or a single-shaft screw feeder.

4. The catalytic cracking process of waste plastics and petroleum mixed feed according to claim 1, characterized in that The high-speed circulation tube is heated by electromagnetic induction heating, thermal oil heating, steam heating or resistance heating, preferably electromagnetic induction heating.

5. The catalytic cracking process of waste plastics and petroleum mixed feed according to claim 1, characterized in that The catalytic cracking reactor is a riser reactor or a downer reactor.

6. The catalytic cracking process of waste plastics and petroleum mixed feed according to claim 1, characterized in that The cracking catalyst is a mixture of one or more of an FCC molecular sieve catalyst, a ZSM-5 selective molecular sieve catalyst, and an alkaline solid porous catalyst.

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