Production device for preparing wax-based chemicals and alpha-olefin through catalytic pyrolysis of waste plastic downer

Abstract

A production device for preparing wax-based chemicals and alpha-olefin through catalytic pyrolysis of a waste plastic downer is characterized in that clean waste plastic is crushed and then is connected into a water-cooling feed pipe through a controllable feeder, a pyrolysis dry gas injection port is formed in the top end of the water-cooling feed pipe, and the bottom end of the water-cooling feed pipe is connected into a hot-melting dechlorination reactor; one path of the bottom of the hot-melting dechlorination reactor returns to the upper part of the hot-melting dechlorination reactor, the other path of the bottom of the hot-melting dechlorination reactor is connected with an atomization feeding nozzle, and a fuel gas extraction opening in the top of the hot-melting dechlorination reactor is communicated with the bottoms of the desulfurization dechlorination reactor and the riser regenerator; atomization feeding nozzles are symmetrically installed on the upper middle portion of a downer catalytic pyrolysis reactor, the bottom of the downer catalytic pyrolysis reactor is connected with an oil-gas-solid separator, a gas-phase outlet of the oil-gas-solid separator is communicated with a fractionating tower, and a solid-phase outlet of the oil-gas-solid separator is communicated with the bottom of a riser regenerator; a first-stage gas-solid separator and a second-stage gas-solid separator are sequentially mounted at the top of the riser regenerator and are communicated with the top of the downer catalytic pyrolysis reactor and the bottom of the riser regenerator; the top of the fractionating tower is communicated with the water-cooling feeding pipe, and the tower bottom is communicated with the upper part of the hot-melting dechlorination reactor.

Description

1. Technical Field

[0001] The invention provides a device for producing wax-based chemicals and alpha-olefins by catalytic pyrolysis of waste plastics in a descending bed, belonging to the field of environmental engineering. 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 waste plastic pyrolysis device in commercial operation, and it is urgent to develop waste plastic downward bed catalytic pyrolysis wax-based chemicals and α-olefin production devices and equipment technologies. 3. Summary of the invention

[0005] The purpose of the present invention is to provide a waste plastic downward bed catalytic pyrolysis device for preparing wax-based chemicals and α-olefins in order to overcome the shortcomings of the existing waste plastic pyrolysis liquefaction technology, and to use pyrolysis dry gas and high-temperature oil slurry circulation to carry out waste plastic hot melt dechlorination and sulfur removal pretreatment and atomization feeding, so as to solve the difficulties in pyrolysis feeding and removal of chlorine and sulfur heteroatoms; catalytic pyrolysis regulates CC bond breakage, inhibits condensation and coke formation, and realizes controllable cracking of waste plastics; adopts a downward bed reactor to inhibit secondary cracking, eliminate the amplification effect, maximize the production of wax-based chemicals and α-olefins, and improve the catalytic pyrolysis heating rate, and 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 amplifying pyrolysis devices, so as to realize efficient, clean and high-value large-scale utilization of waste plastics.

[0006] The technical solution of the present invention:

[0007] The present invention provides a waste plastic descending bed catalytic pyrolysis wax-based chemicals and alpha-olefin production device, wherein the clean PE and PP waste plastic crushers are connected to a water-cooled feed pipe through a controllable feeder, the top of the water-cooled feed pipe is provided with a pyrolysis dry gas injection port, and the bottom of the water-cooled feed pipe is connected to a hot melt dechlorination reactor with stirring, and the bottom of the hot melt dechlorination reactor is connected to a high-speed circulation pipe with heating through a delivery pump on one side and returns to the upper part of the hot melt dechlorination reactor, and the other side is connected to an atomized feed spray port in the middle and upper part of the descending bed catalytic pyrolysis reactor. The gas extraction outlet at the top of the hot melt dechlorination reactor is connected to the desulfurization and dechlorination reactor and the bottom of the riser regenerator in turn. The temperature of the water-cooled feed pipe is 20-95°C, the 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 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 at the upper part of the descending bed catalytic pyrolysis reactor, and the bottom is connected to the bottom of the reactor. The oil-gas gas-solid separator is connected, 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 riser regenerator through the catalyst return device to be produced. The steam dosage of the atomizing feed nozzle is 4% to 12% of the raw material amount, the reaction temperature is 410 to 550°C, the pressure is slightly negative pressure, and the reaction time is 200 milliseconds to 2 seconds; the first-stage gas-solid separator and the second-stage gas-solid separator are installed in sequence on the top of the riser regenerator. The first-stage gas-solid separator is connected to the bottom through the first-stage crude catalyst return device. The top of the running bed catalytic pyrolysis reactor is connected, and the second-stage gas-solid separator is connected to the bottom of the riser regenerator through the secondary fine catalyst return device, and the regeneration temperature is 500-750°C; the distillation tower is provided with a heavy wax oil outlet, a light wax oil outlet, an α-olefin fraction outlet, and a pyrolysis dry gas outlet. The top of the distillation tower is connected to the water-cooled feed pipe through an induced draft fan, and the oil slurry outlet at the bottom of the tower is connected to the upper part of the hot melt dechlorination reactor, realizing a clean and efficient production device for self-thermal melt dechlorination of waste plastics and running bed catalytic pyrolysis to produce wax and α-olefins.

[0008] 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.

[0009] The controllable feeder is a rotary feeder, a double-shaft screw feeder or a single-shaft screw feeder.

[0010] The high-speed circulation tube is heated by electromagnetic induction heating, thermal oil heating, steam heating or resistance heating, preferably electromagnetic induction heating.

[0011] 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.

[0012] The present invention will be described in detail with reference to embodiments. 4. Description of the drawings

[0013] Attached Figure 1 The present invention is a schematic diagram of the process flow of a device for producing wax-based chemicals and α-olefins by catalytic pyrolysis of waste plastics in a descending bed.

[0014] Attached Figure 1 The drawing settings are as follows:

[0015] 1. Waste plastic crusher 2. Controllable feeder 3. Water-cooled feed pipe 4. Hot melt dechlorination reactor 5. Delivery pump 6. High-speed circulation pipe 7. Oil-gas solid separator 8. Desulfurization and dechlorination reactor 9. Fractionation tower 10. Heavy wax oil outlet 11. Light wax oil outlet 12. α-olefin fraction outlet 13. Pyrolysis dry gas outlet 14. Induced draft fan 15. Waste heat boiler 16. Flue gas outlet 17. Regenerated catalyst return device 18. Riser regenerator 19. Gas distributor 20. Inlet pipe 21. Ash discharge port 22. First-stage gas-solid separator 23. First-stage coarse catalyst return device 24. Second-stage gas-solid separator 25. Second-stage fine catalyst return device

[0016] The process characteristics of the present invention are described in detail below in conjunction with the accompanying drawings and embodiments. 5. Specific implementation methods

[0017] The present invention provides a waste plastic descending bed catalytic pyrolysis production device for preparing wax-based chemicals and α-olefins, wherein a clean PE and PP waste plastic crusher (1) is connected to a water-cooled feed pipe (3) through a controllable feeder (2), the top of the water-cooled feed pipe (3) is provided with a pyrolysis dry gas injection port, and the bottom of the water-cooled feed pipe (3) is connected to a hot melt dechlorination reactor (4) with stirring, the bottom of the hot melt dechlorination reactor (4) is connected to a high-speed circulation pipe (6) with heating through a delivery pump (5) and returns to the upper part of the hot melt dechlorination reactor (4), and the other part is connected to an atomizing feed nozzle in the upper part of the descending bed catalytic pyrolysis reactor, and the hot The gas extraction port at the top of the dechlorination reactor (4) is connected to the desulfurization and dechlorination reactor (8) and the bottom of the riser regenerator (18) in sequence, the temperature of the water-cooled feed pipe (3) is 20-95°C, the oil slurry melt is 240-320°C, the temperature of the molten plastic liquid high-speed circulation pipe (6) is 20-60°C higher than the oil slurry melt after heating, the flow rate of the high-speed circulation pipe (6) is 2-30m / s, and the circulation ratio of the molten plastic liquid to the raw material is 1-10:1; the upper part of the down-bed catalytic pyrolysis reactor is symmetrically installed with an atomizing feed nozzle, and the bottom is connected to an oil-gas gas-solid separator (7), and the oil-gas gas-solid separator The liquid phase outlet of the separator (7) is connected to the fractionation tower (9), and the solid phase outlet is connected to the bottom of the riser regenerator (18) through the catalyst return device (17) to be produced. The steam consumption of the atomizing feed nozzle is 4% to 12% of the raw material amount, the reaction temperature is 410 to 550° C., the pressure is slightly negative pressure, and the reaction time is 200 milliseconds to 2 seconds. A first-stage gas-solid separator (22) and a second-stage gas-solid separator (24) are sequentially installed on the top of the riser regenerator (18). The first-stage gas-solid separator (22) is connected to the top of the descending bed catalytic pyrolysis reactor through the first-stage crude catalyst return device (23). The second-stage gas-solid separator (24) is connected to the bottom of the riser regenerator (18) through the second-stage fine catalyst return device (25), and the regeneration temperature is 500-750°C; the fractionation tower (9) is provided with a heavy wax oil outlet (10), a light wax oil outlet (11), an α-olefin fraction outlet (12), and a pyrolysis dry gas outlet (13); the top of the fractionation tower (9) is connected to the water-cooled feed pipe (3) through an induced draft fan (14), and the oil slurry outlet at the bottom of the tower is connected to the upper part of the hot melt dechlorination reactor (4), thereby realizing a clean and efficient production device for waste plastic self-thermal melt dechlorination and bed catalytic pyrolysis to produce wax and α-olefins.

[0018] The outer wall of the water-cooled feed pipe (3) 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.

[0019] The controllable feeder (2) is a rotary feeder, a double-shaft screw feeder or a single-shaft screw feeder.

[0020] The high-speed circulation pipe (6) is heated by electromagnetic induction heating, heat-conducting oil heating, steam heating or resistance heating, preferably electromagnetic induction heating.

[0021] The riser regenerator (18) 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, and the diameter ratio is 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, 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 only 10% to 50% of the equivalent diameter of the turbulent fluidized bed.

[0022] In specific operation, the clean PE and PP waste plastics are sorted through a waste plastic crusher (1), and the waste plastic fragments are added to a 20-95°C water-cooled feed pipe (3) through a controllable feeder (2), and fall into a 240-320°C oil slurry melt in a hot melt dechlorination reactor (4) with stirring under the influence of pyrolysis dry gas, and are subjected to melt dechlorination and desulfurization pretreatment by stirring and mixing. The molten plastic liquid drawn from the bottom of the hot melt dechlorination reactor (4) is conveyed under pressure by a conveying pump (5), a part of which is heated to a temperature 20-60°C higher than that of the oil slurry melt through an externally heated high-speed circulation pipe (6), and then returned to the upper part of the hot melt dechlorination reactor (4), and the other part is returned to the upper part of the hot melt dechlorination reactor (4). The fuel gas extracted from the top of the hot melt dechlorination reactor (4) is treated by the desulfurization and dechlorination reactor (8) and then used as the fuel gas of the riser regenerator (18). The flow rate of the high-speed circulation pipe (6) is 2-30 m / s. The circulation ratio of the molten plastic liquid to the raw material is 1-10:1. The steam consumption of the atomizing feed nozzle is 4%-12% of the raw material amount. The atomized particle feed of the molten plastic liquid is rapidly mixed, vaporized and controllably cracked with the 600-800°C regenerated catalyst falling from the top of the down-bed catalytic pyrolysis reactor. The reaction temperature is 410-55 0℃, slightly negative pressure, reaction time of 200 milliseconds to 2 seconds, maximizing the production of wax-based chemicals and α-olefins, and performing oil-gas-solid separation at the bottom of the descending bed catalytic pyrolysis reactor; the separated catalyst to be regenerated flows into the bottom of the riser regenerator (18) through the catalyst to be regenerated return device (17) to be regenerated by air fluidization charring at 500-750℃ and fuel gas combustion-assisted heating, and is separated into coarse particles by the first-stage gas-solid separator (22) at the top of the riser regenerator (18), and the regenerated catalyst is circulated back to the top of the descending bed catalytic pyrolysis reactor through the first-stage solid heat carrier return device (23) to catalytically pyrolyze the waste plastics, and is separated by the second-stage gas-solid separator (24). The separated fine ash is circulated back to the bottom of the riser regenerator (18) through the hot ash circulation return device (25) to continue fluidized coking regeneration, and the flue gas is discharged after recovering the waste heat through the waste heat boiler (15); the 410-550°C pyrolysis oil gas flows into the distillation tower (9) and is separated into α-olefin fraction, light wax oil, heavy wax oil, pyrolysis dry gas and high-temperature oil slurry through the heavy wax oil outlet (10), the light wax oil outlet (11), the α-olefin fraction outlet (12) and the pyrolysis dry gas outlet (13); 3%-20% of the pyrolysis dry gas is circulated back to the water-cooled feed pipe (3) as a carrier gas, and the high-temperature oil slurry of ≥350°C is directly circulated back to the upper part of the hot melt dechlorination reactor (4) as a melting heat source.

[0023] The downward-bed catalytic pyrolysis device for producing wax-based chemicals and α-olefins of waste plastics can continuously, on a large scale, efficiently, cleanly and in a high-value manner by pyrolysis. It has solved five common problems in the industry, 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 the pyrolysis device, and difficulty in subsequent processing of liquid products containing chlorine. The yield of liquefied gas is ≥10%, the yield of α-olefin fraction is ≥20%, the light wax oil fraction is 40%, the heavy wax oil fraction is 25%, and the total yield of liquid products is more than 95%, which is more than 25 percentage points higher than that of traditional waste plastic pyrolysis technology. It has high pyrolysis intensity, small equipment size, low steel consumption, greatly reduced fixed investment, and a simple ash removal process, thus achieving stable, long-term, full and optimal operation of the device.

Claims

1. A production device for preparing wax-based chemicals and α-olefins by catalytic pyrolysis of waste plastics in a descending bed, wherein the clean PE and PP waste plastic crushers are connected to a water-cooled feed pipe through a controllable feeder, the top of the water-cooled feed pipe is provided with a pyrolysis dry gas injection port, and the bottom is introduced into 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, and the other is connected to an atomizing feed nozzle in the middle and upper part of the descending bed catalytic pyrolysis reactor, the gas extraction port at the top of the hot melt dechlorination reactor is connected to the desulfurization and dechlorination reactor and the bottom of the riser regenerator in turn, 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 molten plastic liquid is symmetrically arranged in the middle and upper part of the descending bed catalytic pyrolysis reactor. An atomizing feed nozzle is installed, and the bottom is connected to an oil-gas gas-solid separator. The liquid phase outlet of the oil-gas gas-solid separator is connected to a fractionation tower, and the solid phase outlet is connected to the bottom of a riser regenerator through a catalyst return device to be produced. The steam dosage of the atomizing feed nozzle is 4wt%-12wt% of the raw material amount, the reaction temperature is 410-550°C, the pressure is 80-100Kpa (absolute pressure), and the reaction time is 200 milliseconds-2 seconds; a first-stage gas-solid separator and a second-stage gas-solid separator are installed in sequence on the top of the riser regenerator, the first-stage gas-solid separator is connected to the top of a descending bed catalytic pyrolysis reactor through a first-stage coarse catalyst return device, and the second-stage gas-solid separator is connected to the bottom of the riser regenerator through a second-stage fine catalyst return device, and the regeneration temperature is 500-750°C; the fractionation tower is provided with a heavy wax oil outlet, a light wax oil outlet, an alpha-olefin fraction outlet, and a pyrolysis dry gas outlet, the top of the fractionation tower is connected to a water-cooled feed pipe through an induced draft fan, and the oil slurry outlet at the bottom of the tower is connected to the upper part of a hot melt dechlorination reactor.

2. The device for producing wax-based chemicals and α-olefins by catalytic pyrolysis of waste plastics in a descending bed 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 wax-based chemicals and α-olefins by catalytic pyrolysis of waste plastics in a downward bed 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 wax-based chemicals and α-olefins by catalytic pyrolysis of waste plastics in a descending bed 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 wax-based chemicals and α-olefins by catalytic pyrolysis of waste plastics in a descending bed 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, the ratio of the diameters 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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