Chemical production plant by fractional gas phase dehydrogenation cracking of waste plastic and crude oil mixed feed

Abstract

The device is composed of a waste plastic self-heating melting dechlorination pretreatment subsystem, a waste plastic melting liquid and crude oil selective vaporization dehydrogenation cracking subsystem, a high-temperature cracking oil gas phase catalytic cracking subsystem and a cracked oil gas fractionation and refining subsystem.

Description

1. TECHNICAL FIELD

[0001] The application provides a device for preparing chemicals by fractional gas phase dehydrogenation cracking of mixed feed of waste plastics and crude oil, and belongs to the field of energy chemical industry. 2. BACKGROUND

[0002] The wide application of plastics brings great convenience to people's life, but also brings a large amount of white pollution. The use cycle of plastics is very short, and a large amount of plastic products, especially packaging materials, are discarded after about 6-12 months, and 40% of plastics are discarded after 1-2 years. The total annual output of waste plastics in the world has reached 50 million tons. In the past few decades, waste plastics have been treated as part of municipal solid waste (MSW). According to the survey, waste plastics account for 4%-10% (wt) or 10%-20% (v%) of MSW in industrialized countries, mainly from packaging waste, automobile waste and processing waste, and the percentage of each variety of waste plastics is: 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 and clean large-scale technology, waste plastics have become an environmental problem to be solved in the world.

[0003] In the treatment of municipal plastic solid waste, three methods of landfill, incineration and recycling are mainly used. Due to different national conditions, different countries have different methods. The United States mainly uses landfill, and Europe and Japan mainly use incineration. At present, fast pyrolysis / catalytic pyrolysis liquefaction or preparation of chemicals from waste plastics has become a hot spot at home and abroad, and is also the most promising waste plastic treatment technology.

[0004] Fast pyrolysis / catalytic pyrolysis of waste plastics is an effective recycling means to decompose waste plastics under anaerobic or low-oxygen conditions at high temperature, and then produce valuable products, such as pyrolysis 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, light quality, difficult compression, poor gas permeability, easy expansion, easy melting and bonding, and poor heat conduction effect, it is difficult to solve the problems of continuous feeding and rapid heating. At present, most of the pyrolysis liquefaction of waste plastics adopts batch reaction and horizontal rotary kiln reaction, the heating rate is slow, the feeding adhesion and coking are serious, the liquid product yield and added value are low, the treatment capacity is difficult to improve, the pyrolysis device is difficult to enlarge, and the follow-up processing of liquid products containing chlorine is difficult, which restricts the efficient and clean large-scale utilization of waste plastics. At present, there is no large-scale commercialized waste plastic pyrolysis device.

[0005] Crude oil graded gas-phase dehydrogenation and cracking to produce chemicals bypasses traditional crude oil processing technologies such as atmospheric and vacuum distillation, catalytic cracking, hydrocracking, and delayed coking, directly producing basic chemical raw materials such as triolefins and triphenyls through catalytic dehydrogenation and cracking. This technology features a short process, simple operation, low cost and energy consumption, and minimal investment, making it the most promising oil-to-oil refining technology for industrialization, adapting to the energy transition brought about by the electrification of automobiles. Combining rapid pyrolysis / catalytic pyrolysis of waste plastics with graded gas-phase dehydrogenation and cracking of crude oil to produce chemicals is an effective means of improving the clean and efficient raw material utilization of waste plastics, reducing oil resource consumption, solving the feed problem of waste plastics pyrolysis, and improving chemical yields and the economic benefits of the equipment. Therefore, there is an urgent need to develop equipment and technology for graded gas-phase dehydrogenation and cracking of chemicals using a mixed feed of waste plastics and crude oil. 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 device for producing chemicals by graded gas-phase dehydrogenation cracking of mixed feed of waste plastic and crude oil. The device utilizes 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, thereby solving the problems of difficult pyrolysis feeding and difficult removal of chlorine and sulfur heteroatoms. The device adopts graded gas-phase catalytic cracking in a downer reactor, and the cracking characteristics of the mixed feed of waste plastic and crude oil complement each other, eliminating the liquid phase cage wall effect, regulating the breakage of CC and CH bonds, inhibiting condensation coking, eliminating the amplification effect, realizing controllable cracking of waste plastic, and maximizing the production of triolefins and triphenyls. The device solves the five common problems in the industry, namely, adhesion and coking of waste plastic feed, difficulty in mixing with heat carriers, low yield and added value of liquid products, difficulty in removing chlorine and sulfur heteroatoms of liquid products, thereby affecting subsequent processing, and difficulty in scaling up the pyrolysis device, thereby realizing efficient, clean, and high-value large-scale utilization of waste plastics and crude oil.

[0007] The technical solution of the present invention:

[0008] The device for producing chemicals by graded gas phase dehydrogenation cracking of mixed feed of waste plastic and crude oil 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 the 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 down-going 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 and the gas extraction outlet at the top of the hot melt dechlorination reactor are connected to the desulfurization and dechlorination reactor and the refinery dry gas 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 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 solid separator. The gas phase outlet of the oil-gas solid separator is connected to the fractionation tower, and the solid phase outlet is regenerated through the return controller and the cracking riser. The bottom of the reactor is connected, and 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. A gas-solid separator installed on the top is connected to the top of the descending cracking reactor through a return device, forming 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 distillation 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 trienes. One line of the distillation 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. Other side lines of the distillation 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 has a shape of a forward cone, a straight tube or an inverted cone, preferably a forward 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 an entrained reactor at the top. The turbulent fluidized bed has a larger equivalent diameter, while the entrained reactor has a smaller equivalent diameter, with a diameter ratio of 2 to 3:1. The entrained reactor can be a straight tube reactor with a uniform equivalent diameter, or it 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 Figures

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

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

[0018] 1. Gas-solid separator, 2. Return controller, 3. Atomizing feed nozzle, 4. Downward cracking reactor, 5. Gas-solid rapid separator, 6. Pyrolysis oil and gas outlet, 7. Return feeder, 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. Fractionator, 17. Crude benzene fraction, 18. Diesel fraction, 19. Recycled oil pump, 20. Hot melt dechlorination reactor, 21. Waste plastic pulverizer, 22. Controllable feeder, 23. Water-cooled feed pipe, 24. Desulfurization and dechlorination reactor, 25. Transfer pump, 26. High-speed circulation pipe, 27. Refinery dry gas network

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

[0020] The device for producing chemicals by mixed feeding of waste plastics and crude oil through graded gas phase dehydrogenation and cracking is provided by the present invention. The device 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. A 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 end 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. (20) The upper part and the other part are connected to the atomizing feed nozzle (3) of the upper part of the down-bed cracking reactor (4) of the selective vaporization dehydrogenation cracking subsystem of the waste plastic melt and crude oil 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-heating melting dechlorination pretreatment subsystem. The water-cooled feed pipe (23) has a temperature of 20-95°C, the oil slurry melt is 240-320°C, the temperature of the molten plastic high-speed circulation pipe (26) after heating is 20-60°C higher than the oil slurry melt, the flow rate of the high-speed circulation pipe (26) is 2-30m / s, and the circulation of the molten plastic 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-flow bed cracking reactor (4); the bottom is connected to an oil-gas-solid separator (5); the liquid phase outlet of the oil-gas-solid separator (5) is communicated with a fractionating tower (16); the solid phase outlet is communicated with 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 communicated with the top of the down-flow cracking reactor (4) through a return material controller (2), forming a selective vaporization dehydrogenation cracking subsystem of waste plastic melt and crude oil; 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 solid separator (5), the gas phase outlet of the oil-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 line of the cracking dry gas pipeline at the top of the fractionating 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 line is connected to the cracking gas refining system to produce triolefins; one line of the refining oil return pipeline of the fractionating tower (16) is connected to the high-temperature molten oil inlet at the top of the hot melt dechlorination reactor (20), and the other line recovers the waste heat and is sent out as a product; the other side lines of the fractionating tower (16) are crude benzene fraction and diesel fraction.

[0021] The outer wall of the water-cooling feed pipe (23) is provided with a water-cooling jacket, which has a shape of a forward cone, a straight pipe or an inverted cone, preferably a forward 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, thermal 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 downlink 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 consists of a turbulent fluidized bed at the bottom and an entrained reactor at the top. The turbulent fluidized bed has a larger equivalent diameter, while the entrained reactor has a smaller equivalent diameter, with a diameter ratio of 2 to 3:1. The entrained reactor is a straight tube reactor with a uniform equivalent diameter, or a series of straight tubes with different diameters connected by large and small head fittings, with a diameter ratio of 1.2 to 2:1. The equivalent diameter of the fluidized bed is 10% to 50% of the equivalent diameter of the turbulent fluidized bed.

[0027] In specific operation, the clean PE and PP waste plastics are sorted through the waste plastic crusher (21), and the waste plastic fragments are added to the water-cooled feed pipe (23) at 20-95°C through the controllable feeder (22). Under the influence of cracking dry gas, they fall into the 240-320°C oil slurry melt of the hot melt dechlorination reactor (20) with stirring, and are melted, 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 the 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). The other part is sent to the upper part of the downward cracking reactor (4) together with the crude oil as raw material through the atomizing feed nozzle (3). The gas extracted from the top of the hot melt dechlorination reactor (20) is processed 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 steam dosage of (3) is 4% to 12% of the raw material amount; the atomized particle feed of the mixture of the molten plastic liquid and the crude oil is quickly 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 steam dosage 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 oil-gas-solid separation (5) is carried out at the bottom of the descending cracking reactor (4); the separated The catalyst flows through a return device (7) into the bottom of a cracking riser regenerator (10) and is regenerated by burning in air 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 is separated by the gas-solid separator (1) at the top of the cracking riser regenerator (10) and 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 into the gas phase feed hole in the upper part of the descending cracking reactor (8) without being condensed, 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 carried out 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 at 600-750°C. The cracking riser regenerator (10) is provided with an air inlet (14) at the bottom and a gas-solid separator (1), a heat exchanger (11) and a regeneration flue gas outlet (15) at the top. 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 line of the cracking dry gas pipeline 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 line is connected to the cracking gas refining system for producing triolefins. One line of the fractionation tower (16) refining pipeline is connected to the high-temperature molten oil inlet at the top of the hot melt dechlorination reactor (20), and the other line recovers the waste heat and is sent out as a product. Other side lines of the fractionation tower (16) are crude benzene fraction and diesel fraction.

[0028] The device for producing chemicals through graded gas-phase dehydrogenation and cracking of mixed feed of waste plastics and crude oil can continuously, efficiently and cleanly produce trienes and triphenyls and other high-value-added chemicals from waste plastics and crude oil on a large scale. It solves 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 scaling up pyrolysis equipment, and difficulty in subsequent processing of chlorine-containing liquid products. The triene yield is ≥50%, the triphenyls yield is ≥15%, the diesel yield is ≥20%, and the total liquid product yield is above 93% (including liquefied gas), which is more than 25 percentage points higher than the traditional waste plastic pyrolysis technology, ensuring safe, stable, full and excellent operation of the device.

Claims

1. A device for producing chemicals by using mixed feed of waste plastics and crude oil for graded vapor-phase dehydrogenation and cracking. Its technical characteristics include the following: it comprises a waste plastic self-heating melt dechlorination pretreatment subsystem, a waste plastic melt and crude oil selective vaporization and dehydrogenation cracking subsystem, a high-temperature cracking oil and gas vapor-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 via 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 via a delivery pump, which returns to the upper part of the hot-melt dechlorination reactor. The other part is connected to the descending bed of the waste plastic melt and crude oil selective vaporization and dehydrogenation cracking subsystem together with the crude oil feed pipeline. The atomizing feed nozzle in the upper part of the cracking reactor and the gas extraction port at the top of the hot melt dechlorination reactor are connected in sequence with the desulfurization and dechlorination reactor and the refinery dry gas network, forming a waste plastic self-thermal melt dechlorination pretreatment subsystem. The temperature of the water-cooled feed pipe is 20-95°C, the temperature of 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 the temperature of the oil slurry melt, the flow rate of the high-speed circulation pipe is 2-30m / s, and the ratio of the circulating material to the raw material of the molten plastic liquid is 1-10:1; the atomizing feed nozzle is symmetrically installed in the upper part of the down-bed cracking reactor, and the bottom is connected to the oil-gas-solid separator. The gas phase outlet of the oil-gas-solid separator is connected to the down-bed cracking reactor, and the solid phase outlet is connected to the down-bed cracking reactor through the return controller. The bottom of the cracking riser 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%~12wt% of the raw material amount, the cracking reaction temperature is 500~550℃, the pressure is 0-0.3MPa, the reaction time is 600ms~2s, and the regeneration temperature is 500-750℃; gas phase feed holes are evenly provided 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. A gas-solid separator is installed on the top of the riser regenerator and is connected to the top of the descending cracking reactor through a return device, forming a high-temperature cracking oil and gas gas-phase catalytic cracking subsystem. The cracking reaction temperature is 570-650℃, the pressure is 0-0.3MPa, the reaction time is 200 milliseconds to 1 second, and the regeneration temperature is 600-750℃; the cracking dry gas pipeline at the top of the distillation 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 on one side, and is connected to the cracking gas refining system to produce trienes on the other side. The refining oil pipeline at the bottom of the distillation tower is connected to the high-temperature molten oil inlet on the top of the hot melt dechlorination reactor on one side, and is sent out as a product after recovering the waste heat on the other side. The other side lines of the distillation tower are crude benzene fraction and diesel fraction.

2. The device for producing chemicals by mixing waste plastics and crude oil into a graded gas phase dehydrogenation cracking system according to claim 1, characterized in that The outer wall of the water-cooled feed pipe is provided with a water-cooling jacket, which has a shape of a positive cone, a straight pipe or an inverted cone.

3. The device for producing chemicals by mixing waste plastics and crude oil into a mixed feedstock and performing gas phase dehydrogenation cracking is according to claim 1, characterized in that The controllable feeder is a rotary feeder.

4. The device for producing chemicals by mixing waste plastics and crude oil into a graded gas phase dehydrogenation cracking system according to claim 1, characterized in that The controllable feeder is a double-shaft screw feeder or a single-shaft screw feeder.

5. The device for producing chemicals by mixing waste plastics and crude oil into a mixed feedstock and performing gas phase dehydrogenation 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.

6. The device for producing chemicals by mixing waste plastics and crude oil into a graded gas phase dehydrogenation cracking system 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.

7. The device for producing chemicals by mixing waste plastics and crude oil into a mixed feedstock and performing gas phase dehydrogenation 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 and an alkaline solid porous catalyst.

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

9. The device for producing chemicals by mixing waste plastics and crude oil into a graded gas phase dehydrogenation cracking system according to claim 1, characterized in that The riser regenerator consists 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 2~3:

1. The entrained reactor is a straight tube reactor, or straight tubes of different diameters are connected by large and small head pipe fittings. The diameter ratio of the large and small straight tubes is 1.2~2:1.

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