Device for preparing chemicals through mixed feeding, grading, gas-phase dehydrogenation and cracking of waste plastics and crude oil

Abstract

A device for preparing chemicals through waste plastic and crude oil mixed feeding grading gas-phase dehydrogenation cracking is composed of a waste plastic self-hot-melting dechlorination pretreatment subsystem, a waste plastic melting liquid and crude oil selective vaporization dehydrogenation cracking subsystem, a high-temperature cracked oil gas gas-phase catalytic cracking subsystem and a cracked oil gas fractionation and refining subsystem. A recycle oil pipeline and a cracking dry gas pipeline of the cracking oil-gas fractionation and refining subsystem are respectively connected to a high-temperature molten oil inlet and a feeding carrying gas inlet of the waste plastic self-heating melting dechlorination pretreatment subsystem, and a waste plastic molten liquid delivery pipeline of the waste plastic self-heating melting dechlorination pretreatment subsystem is connected to a crude oil feeding pipeline; a waste plastic and crude oil mixed feeding pipeline is connected into the waste plastic molten liquid and crude oil selective vaporization dehydrogenation cracking subsystem through an atomizing nozzle, selective vaporization dehydrogenation cracking and gas-phase catalytic cracking are sequentially completed in a grading mode, and then the cracked oil gas fractionation and refining subsystem produces triene tribenzene, high-temperature recycle oil and cracked dry gas.

Description

1. Technical Field

[0001] The invention provides a device for preparing chemicals by mixed feeding of waste plastics and crude oil through graded gas phase dehydrogenation and cracking, 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] Crude oil graded gas phase dehydrogenation cracking to produce chemicals directly bypasses traditional crude oil processing technology routes such as atmospheric and vacuum distillation, catalytic cracking, hydrocracking, and delayed coking, and directly catalytically dehydrogenates and cracks to produce basic chemical raw materials such as triolefins and triphenyls. It has a short process, simple operation, low cost and energy consumption, and low investment. It is the most promising oil "oil conversion" refining technology for industrialization to adapt to the energy transformation brought about by automobile electrification. Combining rapid pyrolysis / catalytic pyrolysis of waste plastics with crude oil graded gas phase dehydrogenation cracking to produce chemicals is an effective means to improve the clean and efficient raw material utilization of waste plastics, reduce the consumption of petroleum resources, solve the problem of waste plastic pyrolysis feed, and improve the chemical yield and economic benefits of the device. It is urgent to develop waste plastics and crude oil mixed feed graded gas phase dehydrogenation cracking to produce chemicals and equipment technology. 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 waste plastic and crude oil mixed feed graded gas phase dehydrogenation cracking device for preparing chemicals, use pyrolysis dry gas and high-temperature refining oil circulation to carry out waste plastic hot melt dechlorination and sulfur pretreatment and liquid phase atomization feeding, solve the difficult problems of pyrolysis feeding and chlorine and sulfur heteroatom removal; adopt down-going bed reactor graded gas phase catalytic cracking, the cracking characteristics of waste plastic and crude oil mixed raw materials complement each other, eliminate the liquid phase cage wall effect, regulate the breakage of CC and CH bonds, inhibit condensation coke, 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 products, difficulty in removing chlorine and sulfur heteroatoms of liquid products thus affecting subsequent processing, and difficulty in amplifying pyrolysis devices, and realize efficient, clean and high-value large-scale utilization of waste plastics and crude oil.

[0007] The technical solution of the present invention:

[0008] The waste plastic and crude oil mixed feed graded gas phase dehydrogenation cracking device for producing chemicals is composed of a waste plastic self-thermal melting dechlorination pretreatment subsystem, a waste plastic melt and crude oil selective vaporization dehydrogenation cracking subsystem, a high-temperature cracking oil and gas gas phase catalytic cracking subsystem, and a cracking oil and gas fractionation and refining subsystem. The waste plastic crusher is connected to a water-cooled feed pipe through a controllable feeder. The top of the water-cooled feed pipe is provided with a cracking dry gas injection inlet, and the bottom is connected to a hot melt dechlorination reactor with stirring. The bottom of the hot melt dechlorination reactor is connected to a high-speed circulation pipe with heating through a delivery pump and returns to the upper part of the hot melt dechlorination reactor. The other way is connected to the descending bed cracking reactor of the waste plastic melt and crude oil selective vaporization dehydrogenation cracking subsystem together with the crude oil feed pipeline. The atomizing feed nozzle in the upper part of the reactor, the gas extraction outlet at the top of the hot melt dechlorination reactor is connected with the desulfurization and dechlorination reactor and the refinery dry gas pipeline network, forming a waste plastic self-thermal melt dechlorination pretreatment subsystem, the temperature of the water-cooled feed pipe is 20-95°C, the oil slurry melt is 240-320°C, the temperature of the molten plastic liquid high-speed circulation pipe after heating is 20-60°C higher than that of the oil slurry melt, the flow rate of the high-speed circulation pipe is 2-30m / s, and the circulation ratio of the molten plastic liquid to the raw material is 1-10:1; the atomizing feed nozzle is symmetrically installed in the upper part of the down-bed catalytic pyrolysis reactor, and the bottom is connected to the oil-gas gas-solid separator, the gas phase outlet of the oil-gas gas-solid separator is connected to the fractionation tower, and the solid phase outlet is regenerated through the return material controller and the cracking riser. The bottom of the reactor is connected, a gas-solid separator is installed on the top of the cracking riser regenerator and is connected to the top of the descending cracking reactor through a return controller to form a waste plastic melt and crude oil selective vaporization dehydrogenation cracking subsystem, the steam dosage of the atomizing feed nozzle is 4% to 12% 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 the regeneration temperature is 500-750°C; gas phase feed holes are evenly arranged on the circumference of the upper part of the descending cracking reactor, and the bottom is connected to the oil-gas gas-solid separator, the gas phase outlet of the oil-gas gas-solid separator is connected to the fractionation tower, and the solid phase outlet is connected to the bottom of the cracking riser regenerator through a return device, and the gas phase outlet of the oil-gas gas-solid separator is connected to the fractionation tower, and the solid phase outlet is connected to the bottom of the cracking riser regenerator through a return device. The gas-solid separator installed on the top is connected to the top of the descending cracking reactor through a return device to form a high-temperature cracking oil and gas gas-phase catalytic cracking subsystem. The cracking reaction temperature is 570-650°C, the pressure is 0-0.3MPa, the reaction time is 200 milliseconds to 1 second, and the regeneration temperature is 600-750°C; one cracking dry gas pipeline at the top of the fractionation tower of the cracking oil and gas fractionation and refining subsystem is connected to the feed carrying gas inlet of the water-cooled feed pipe at the top of the hot melt dechlorination reactor, and the other is connected to the cracking gas refining system to produce triolefins. One line of the fractionation tower refining pipeline is connected to the high-temperature molten oil inlet at the top of the hot melt dechlorination reactor, and the other line recovers the waste heat and is sent out as a product. The other side lines of the fractionation tower are crude benzene 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 catalyst used in the descending cracking reaction tube is a mixture of one or more of semi-coke microspheres, alumina microspheres, calcium aluminate porous microspheres, magnesium aluminum spinel porous microspheres, aluminum silicate porous microspheres, calcium silicate porous microspheres, magnesium silicate porous microspheres, and porous microsphere carriers loaded with alkali metals and / or alkaline earth metals.

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

[0014] The riser regenerator is composed of a turbulent fluidized bed at the bottom and a carrying reactor at the top. The turbulent fluidized bed has a larger equivalent diameter, while the carrying reactor has a smaller equivalent diameter, with a diameter ratio of 2 to 3:1. The carrying reactor can be a straight tube reactor with a uniform equivalent diameter, or can be composed of large and small straight tubes with diameters of different multiples of the equivalent diameter connected by large and small head pipe fittings, with a diameter ratio of 1.2 to 2:1. The equivalent diameter of the fluidized bed is only 10%-50% of the equivalent diameter of the turbulent fluidized bed.

[0015] The present invention will be described in detail with reference to embodiments. 4. Description of the drawings

[0016] Attached Figure 1 The present invention is a schematic diagram of the process flow of a device for producing chemicals by mixed feeding of waste plastics and crude oil through graded gas phase dehydrogenation and cracking.

[0017] Attached Figure 1 The drawing settings are as follows:

[0018] 1. Gas-solid separator, 2. Feed return controller, 3. Atomizing feed nozzle, 4. Downward cracking reaction tube, 5. Gas-solid quick separator, 6. Pyrolysis oil and gas outlet, 7. Feed return, 8. Downward cracking reactor, 9. Regeneration agent inlet, 10. Cracking riser regeneration reactor, 11. Heat exchanger, 12. Regeneration flue gas outlet, 13. Cracking riser regeneration reactor, 14. Air inlet, 15. Flue gas outlet, 16. Fractionation tower, 17. Crude benzene fraction, 18. Diesel fraction, 19. Refining oil pump, 20. Hot melt dechlorination reactor, 21. Waste plastic crusher, 22. Controllable feeder, 23. Water-cooled feed pipe, 24. Desulfurization and dechlorination reactor, 25. Delivery pump, 26. High-speed circulation pipe, 27. Refinery dry gas network

[0019] The process characteristics of the present invention are described in detail below in conjunction with the accompanying drawings and embodiments. 5. Specific implementation methods

[0020] The waste plastic and crude oil mixed feed graded gas phase dehydrogenation cracking device for producing chemicals provided by the present invention comprises a waste plastic self-thermal melting dechlorination pretreatment subsystem, a waste plastic melt and crude oil selective vaporization dehydrogenation cracking subsystem, a high temperature cracking oil and gas gas phase catalytic cracking subsystem, and a cracking oil and gas fractionation and refining subsystem. The waste plastic crusher (21) is connected to a water-cooled feed pipe (23) through a controllable feeder (22). The top of the water-cooled feed pipe (23) is provided with a cracking dry gas injection port, and the bottom is connected to a hot melt dechlorination reactor (20) with stirring. The bottom of the hot melt dechlorination reactor (20) is connected to a high-speed circulation pipe (26) with heating through a delivery pump (25) and returns to the hot melt dechlorination reactor. The other part is connected to the atomizing feed nozzle (3) in the upper middle part of the descending bed cracking reactor (4) of the waste plastic molten liquid and crude oil selective vaporization dehydrogenation cracking subsystem together with the crude oil feed pipeline. The gas extraction outlet at the top of the hot melt dechlorination reactor (20) is connected to the desulfurization and dechlorination reactor (24) and the cracking dry gas pipeline (27), forming a waste plastic self-thermal melting dechlorination pretreatment subsystem. The water-cooled feed pipe (23) has a temperature of 20-95°C, the oil slurry molten liquid is 240-320°C, the temperature of the molten plastic liquid high-speed circulation pipe (26) after heating is 20-60°C higher than that of the oil slurry molten liquid, the flow rate of the high-speed circulation pipe (26) is 2-30m / s, and the circulation of the molten plastic liquid is consistent with the raw material. The ratio is 1 to 10:1; an atomizing feed nozzle (3) is symmetrically installed in the upper part of the down-going bed cracking reactor (4); the bottom is connected to an oil-gas gas-solid separator (5); the liquid phase outlet of the oil-gas gas-solid separator (5) is connected to a fractionation tower (16); the solid phase outlet is connected to the bottom of a cracking riser regenerator (10) through a return material controller (2); a gas-solid separator (1) is installed on the top of the cracking riser regenerator (10) and is connected to the top of the down-going cracking reactor (4) through a return material controller (2), forming a waste plastic melt and crude oil selective vaporization dehydrogenation cracking subsystem; the steam consumption of the atomizing feed nozzle (3) is 4% to 12% 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 the regeneration temperature is 500-750°C; gas phase feed holes are evenly arranged on the circumference of the upper part of the descending cracking reactor (8), and the bottom is connected to the oil-gas gas-solid separator (5), the gas phase outlet of the oil-gas gas-solid separator (5) is connected to the fractionation tower (16), and the solid phase outlet is connected to the bottom of the cracking riser regenerator (13) through the return device (7), and the gas-solid separator (1) is installed on the top of the cracking riser regenerator (13) and is connected to the top of the descending cracking reactor (8) through the return device (7), forming a high-temperature cracking oil-gas gas-phase catalytic cracking subsystem, the cracking reaction temperature is 570-650°C, and the pressure is 0-0.3MPa, reaction time is 200 milliseconds to 1 second, and regeneration temperature is 600-750℃; one of the cracking dry gas pipelines at the top of the fractionation tower (3) of the cracking oil and gas fractionation and refining subsystem is connected to the feed carrying gas inlet of the water-cooled feed pipe (23) at the top of the hot melt dechlorination reactor (20), and the other is connected to the cracking gas refining system to produce triolefins; one of the oil refining pipelines of the fractionation tower (16) is connected to the high-temperature molten oil inlet at the top of the hot melt dechlorination reactor (20), and the other is sent out as a product after recovering the waste heat; the other side lines of the fractionation tower (16) are crude benzene fraction and diesel fraction.

[0021] The outer wall of the water-cooled feed pipe (23) 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.

[0022] The controllable feeder (22) is a rotary feeder, a double-shaft screw feeder or a single-shaft screw feeder.

[0023] The high-speed circulation pipe (26) is heated by electromagnetic induction heating, heat-conducting oil heating, steam heating or resistance heating, preferably electromagnetic induction heating.

[0024] The catalyst used in the descending cracking reaction tube (4) is a mixture of one or more of semi-coke microspheres, alumina microspheres, calcium aluminate porous microspheres, magnesium aluminum spinel porous microspheres, aluminum silicate porous microspheres, calcium silicate porous microspheres, magnesium silicate porous microspheres, and porous microsphere carriers loaded with alkali metals and / or alkaline earth metals.

[0025] The catalyst used in the downstream cracking reactor (8) is a mixture of one or more of an FCC molecular sieve catalyst, a ZSM-5 type selective molecular sieve catalyst, and an alkaline solid porous catalyst.

[0026] The riser regenerator is composed of a turbulent fluidized bed at the bottom and a carrying reactor at the top. The equivalent diameter of the turbulent fluidized bed is larger, and the equivalent diameter of the carrying reactor is smaller, and the diameter ratio is 2 to 3:1. The carrying reactor is a straight tube reactor with a uniform equivalent diameter, or is connected by large and small straight tubes with diameters of different multiples of the equivalent diameter through large and small head pipe fittings, and the diameter ratio of the large and small straight tubes is 1.2 to 2:1. The equivalent diameter of the fluidized bed is 10%-50% of the equivalent diameter of the turbulent fluidized bed.

[0027] In specific operation, the clean PE and PP waste plastics are sorted through a waste plastic crusher (21), and the waste plastic fragments are added to a 20-95° C. water-cooled feed pipe (23) through a controllable feeder (22), and fall into a 240-320° C. oil slurry melt in a hot melt dechlorination reactor (20) with stirring under the influence of cracking dry gas, and are melted and dechlorinated and desulfurized by stirring and mixing. The molten plastic liquid extracted from the bottom of the hot melt dechlorination reactor (20) is pressurized and transported by a delivery pump (25), and a part of it is transported by a high-speed circulation system with external heating. The loop pipe (26) is heated to a temperature 20-60°C higher than the temperature of the slurry melt and then returns to the upper part of the hot melt dechlorination reactor (20). Another part is sent to the upper part of the downward cracking reactor (4) together with the crude oil as a raw material through the atomizing feed nozzle (3). The gas extracted from the top of the hot melt dechlorination reactor (20) is treated by the desulfurization and dechlorination reactor (24) and then enters the refinery gas network as fuel gas. The flow rate of the high-speed circulation pipe (25) is 2-30 m / s. The circulation ratio of the molten plastic liquid to the raw material is 1-10:1. The atomizing feed nozzle 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 crude oil is rapidly mixed, vaporized and subjected to a controllable cracking reaction with the cracking regeneration catalyst falling from the top of the descending 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 to 0.3 MPa, the reaction time is 600 milliseconds to 2 seconds, and oil-gas-solid separation (5) is performed at the bottom of the descending cracking reactor (4); the separated regenerated catalyst to be regenerated is then subjected to a controlled cracking reaction. The catalyst flows into the bottom of the cracking riser regenerator (10) through a return device (7) and is regenerated by air fluidization burning at 500-750°C. The bottom of the cracking riser regenerator (10) is provided with a regeneration air inlet (9), and the top is provided with a gas-solid separator (1), a heat exchanger (11) and a regeneration flue gas outlet (12) in sequence. The regenerated catalyst separated by the gas-solid separator (1) at the top of the cracking riser regenerator (10) is circulated back to the top of the descending cracking reactor (4) through a return controller (2) to catalytically crack the mixture of molten plastic liquid and crude oil.The high-temperature cracking oil and gas are directly sprayed from the gas phase feed hole in the upper part of the descending cracking reactor (8) without condensation, and are rapidly mixed with the cracking regeneration catalyst falling from the top and undergo a controllable cracking reaction. The oil and gas gas-solid separation (5) is performed at the bottom of the descending cracking reactor (8). The cracking reaction temperature is 570-650°C, the pressure is 0-0.3MPa, and the reaction time is 200 milliseconds to 1 second. The separated cracking catalyst to be regenerated flows into the bottom of the cracking riser regenerator (113) through a return device (7) and is regenerated by air fluidization burning at 600-750°C. The bottom of the cracking riser regenerator (10) is provided with an air inlet (14), and the top is provided with a gas-solid separator (1), a heat exchanger (11) and a regeneration flue gas outlet (15) in sequence. The cracking regeneration catalyst separated by the gas-solid separator (1) at the top of the cracking riser regenerator (13) is circulated back to the top of the descending cracking reactor (13) through the return device (7) to catalytically crack the high-temperature cracking oil and gas. The high-temperature cracking oil and gas enter the fractionation tower (3) for separation. One of the cracking dry gas pipelines at the top of the fractionation tower (3) is connected to the feed carrying gas inlet of the water-cooled feed pipe (23) at the top of the hot melt dechlorination reactor (20), and the other is connected to the cracking gas refining system to produce triolefins. One of the oil refining pipelines of the fractionation tower (16) is connected to the high-temperature molten oil inlet at the top of the hot melt dechlorination reactor (20), and the other is sent out as a product after recovering the waste heat. The other side lines of the fractionation tower (16) are crude benzene fraction and diesel fraction.

[0028] The device for producing chemicals by graded gas-phase dehydrogenation and cracking of mixed feed of waste plastics and crude oil is capable of continuously, on a large scale, efficiently and cleanly utilizing waste plastics and crude oil to produce high value-added chemicals such as triolefins and triphenyls. It has solved five common industry problems, namely, adhesion and coking of waste plastic feed, difficulty in mixing with high-temperature catalysts, low yield and added value of liquid products, difficulty in scaling up pyrolysis equipment, and difficulty in subsequent processing of liquid products containing chlorine. The triolefins yield is ≥50%, the triphenyls yield is ≥15%, the diesel yield is ≥20%, and the total yield of liquid products is above 93% (including liquefied gas), which is more than 25 percentage points higher than that of traditional waste plastic pyrolysis technology, thus achieving safe, stable, full and optimal operation of the device.

Claims

1. A device for producing chemicals by gas phase dehydrogenation and cracking of mixed feed of waste plastics and crude oil, which is technically characterized by comprising a waste plastic self-thermal melting dechlorination pretreatment subsystem, a waste plastic melt and crude oil selective vaporization dehydrogenation cracking subsystem, a high temperature cracking oil and gas gas phase catalytic cracking subsystem, and a cracking oil and gas fractionation and refining subsystem. The waste plastic crusher is connected to a water-cooled feed pipe through a controllable feeder. The top of the water-cooled feed pipe is provided with a cracking dry gas injection port, and the bottom is connected to a hot melt dechlorination reactor with stirring. The bottom of the hot melt dechlorination reactor is connected to a high-speed circulation pipe with heating through a delivery pump and returns to the upper part of the hot melt dechlorination reactor. The other way is connected to the waste plastic melt and crude oil selective vaporization dehydrogenation cracking subsystem together with the crude oil feed pipeline. The atomizing feed nozzle in the upper part of the down-bed cracking reactor and the gas extraction port at the top of the hot melt dechlorination reactor are connected with the desulfurization and dechlorination reactor and the refinery dry gas network, forming a waste plastic self-thermal melting dechlorination pretreatment subsystem. The temperature of the water-cooled feed pipe is 20-95°C, the oil slurry melt is 240-320°C, the temperature of the molten plastic liquid high-speed circulation pipe after heating is 20-60°C higher than that of the oil slurry melt, the flow rate of the high-speed circulation pipe is 2-30m / s, and the circulation ratio of the molten plastic liquid to the raw material is 1-10:1; the atomizing feed nozzle is symmetrically installed in the upper part of the down-bed catalytic pyrolysis reactor, and the bottom is connected to the oil-gas gas-solid separator. The gas phase outlet of the oil-gas gas-solid separator is connected to the fractionation tower, and the solid phase outlet is connected to the cracking lift through the return material controller. The bottom of the tube regenerator is connected, and a gas-solid separator is installed on the top of the cracking riser regenerator and connected to the top of the descending cracking reactor through a return controller to form a waste plastic melt and crude oil selective vaporization dehydrogenation cracking subsystem, 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 the regeneration temperature is 500-750°C; gas phase feed holes are evenly arranged on the circumference of the upper part of the descending cracking reactor, and the bottom is connected to the oil-gas gas-solid separator, the gas phase outlet of the oil-gas gas-solid separator is connected to the fractionation tower, and the solid phase outlet is connected to the bottom of the cracking riser regenerator through a return device, and the cracking riser is connected to the bottom of the cracking riser. A gas-solid separator is installed on the top of the tube regenerator and is connected to the top of the descending cracking reactor through a return device to form a high-temperature cracking oil and gas gas-phase catalytic cracking subsystem. The cracking reaction temperature is 570-650°C, the pressure is 0-0.3MPa, the reaction time is 200 milliseconds to 1 second, and the regeneration temperature is 600-750°C; one cracking dry gas pipeline at the top of the fractionation tower of the cracking oil and gas fractionation and refining subsystem is connected to the feed carrying gas inlet of the water-cooled feed pipe at the top of the hot melt dechlorination reactor, and the other is connected to the cracking gas refining system to produce triolefins. One line of the fractionation tower refining pipeline is connected to the high-temperature molten oil inlet at the top of the hot melt dechlorination reactor, and the other line recovers the waste heat and is sent out as a product. The other side lines of the fractionation tower are crude benzene fraction and diesel fraction.

2. The device for producing chemicals by mixed feeding of waste plastics and crude oil through graded gas phase dehydrogenation and cracking according to claim 1, characterized in that The outer wall of the water-cooled feed pipe 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.

3. The device for producing chemicals by mixed feeding of waste plastics and crude oil through graded gas phase dehydrogenation and cracking 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 device for producing chemicals by mixed feeding of waste plastics and crude oil through graded gas phase dehydrogenation and cracking 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 device for producing chemicals by mixed feeding of waste plastics and crude oil through graded gas phase dehydrogenation and cracking according to claim 1, characterized in that The catalyst used in the descending cracking reaction tube is a mixture of one or more of semi-coke microspheres, alumina microspheres, calcium aluminate porous microspheres, magnesium aluminum spinel porous microspheres, aluminum silicate porous microspheres, calcium silicate porous microspheres, magnesium silicate porous microspheres, and porous microsphere carriers loaded with alkali metals and / or alkaline earth metals.

6. The device for producing chemicals by mixed feeding of waste plastics and crude oil through graded gas phase dehydrogenation and cracking according to claim 1, characterized in that The catalyst used in the downlink cracking reactor is a mixture of one or more of an FCC molecular sieve catalyst, a ZSM-5 type selective molecular sieve catalyst, and an alkaline solid porous catalyst.

7. The device for producing chemicals by mixed feeding of waste plastics and crude oil through graded gas phase dehydrogenation and cracking according to claim 1, characterized in that The riser regenerator is composed of a turbulent fluidized bed at the bottom and an entrained reactor at the top, the ratio of the equivalent diameter of the turbulent fluidized bed to the equivalent diameter of the entrained reactor is 2 to 3:1; the entrained reactor is a straight tube reactor with a uniform equivalent diameter, or is composed of large and small straight tubes with diameters of different multiples of the equivalent diameter connected by large and small head pipe fittings, and the diameter ratio of the large and small straight tubes is 1.2 to 2:1; the equivalent diameter of the fluidized bed is 10%-50% of the equivalent diameter of the turbulent fluidized bed.

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