Method for producing high-value products through mixed catalytic cracking of waste plastics and heavy oil

Abstract

The invention relates to the technical field of high-value chemical recycling of waste plastics, in particular to a method for producing a high-value product through mixed catalytic cracking of waste plastics and heavy oil, which comprises the following steps: A) crushing the waste plastics, and carrying out anhydrous cleaning treatment to obtain clean waste plastic fragments; b) mixing the clean waste plastic fragments with a solvent in a liquefaction unit, and heating and liquefying to obtain waste plastic liquefied liquid; c) filtering the waste plastic liquefied liquid in a filtering unit; d) contacting the filtered filtrate with a fluidized catalyst in a catalytic cracking unit for catalytic cracking reaction to obtain an oil-gas mixture and a spent catalyst; e) performing product separation on the oil-gas mixture; heavy oil is recycled to the liquefaction unit; conveying the spent catalyst to a catalyst regeneration unit, and regenerating under an aerobic condition; the regenerated hot catalyst circularly enters the catalytic cracking unit. According to the invention, high-valued cyclic utilization of the waste plastics can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of high-value chemical cycle recycling of waste plastics, and in particular to a method for producing high-value products by mixed catalytic cracking of waste plastics and heavy oil. Background Art

[0002] With the rapid development of modern industry, plastic products have become an indispensable part of people's daily life. Plastics are widely used in agriculture, household, automobile, packaging materials, toys, electronics and other fields due to their light weight, easy processing, high strength and strong corrosion resistance. For decades, the global plastic production has continued to grow, resulting in a sharp increase in the amount of global waste plastics. Since waste plastics are difficult to degrade, the waste plastics left in the environment form the so-called "white pollution", which has a serious negative impact on the environment and ecosystem.

[0003] At present, the main methods of treating waste plastics are landfill, incineration, melting regeneration and chemical recycling. Landfill and incineration were once widely used in the treatment of waste plastics. The toxic leachate or dioxin produced by landfill or incineration of waste plastics will cause serious pollution to the soil and atmosphere. At the same time, waste plastics are petrochemical resources with high carbon and hydrogen content. Incineration and landfill are a serious waste of petrochemical resources. Therefore, in order to optimize the energy structure and promote the transformation from petrochemical energy to renewable energy, it is urgent to develop economical and efficient waste plastic recycling technology. Summary of the invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a method for producing high-value products by mixed catalytic cracking of waste plastics and heavy oil, which can realize large-scale continuous catalytic cracking of waste plastics and efficiently convert them into high-value products such as low-carbon olefins, aromatics, gasoline and diesel, thereby realizing high-value recycling of waste plastics.

[0005] The present invention provides a method for producing high-value products by catalytic cracking of mixed waste plastics and heavy oil, comprising the following steps:

[0006] A) After the waste plastics are crushed, they are subjected to anhydrous cleaning treatment to obtain clean waste plastic fragments;

[0007] B) mixing the clean waste plastic fragments with a solvent in a liquefaction unit, heating and liquefying, to obtain a waste plastic liquefied liquid;

[0008] C) filtering the waste plastic liquefied liquid in a filtering unit;

[0009] D) contacting the filtered filtrate with a fluidized catalyst in a catalytic cracking unit to perform a catalytic cracking reaction to obtain an oil-gas mixture and a catalyst to be produced;

[0010] E) separating the oil-gas mixture into products to obtain dry gas, light olefins, aromatics, gasoline, diesel and heavy oil; the heavy oil is recycled to the liquefaction unit;

[0011] The catalyst to be regenerated is transported to a catalyst regeneration unit and regenerated under aerobic conditions; the regenerated hot catalyst is circulated into the catalytic cracking unit.

[0012] Preferably, the waste plastic is garbage waste plastic, including one or more of high-density polyethylene, low-density polyethylene, polypropylene, polyvinyl chloride, polystyrene and polyethylene terephthalate; the mass content of polyvinyl chloride in the waste plastic is less than 1.0%.

[0013] Preferably, the size of the crushed plastic fragments is 0.5 to 5.0 cm;

[0014] The waterless cleaning treatment method includes slag removal, hot air drying, gas-solid separation, dust removal and odor removal;

[0015] The temperature of the hot air drying is 80-180°C.

[0016] Preferably, the clean waste plastic fragments are fed into the liquefaction unit via a feeding device; the feeding device comprises one of a hopper and a screw propeller;

[0017] The feeding device uses an inert protective gas to isolate oxygen; the inert protective gas includes at least one of nitrogen, helium and argon.

[0018] Preferably, the solvent includes one or more of heavy oil, light cycle oil and wax oil;

[0019] The heavy oil includes one or more of atmospheric heavy oil, vacuum gas oil, catalytic cracking heavy oil, hydrocracking heavy oil and visbroken heavy oil;

[0020] The light cycle oil includes one or more of straight-run diesel, catalytic cracking diesel, hydrocracked diesel and coker diesel;

[0021] The wax oil includes one or more of atmospheric wax oil, vacuum wax oil and hydrogenated wax oil.

[0022] Preferably, the liquefaction unit comprises a primary liquefaction kettle, a secondary liquefaction kettle, a solid-liquid separator and a tertiary liquefaction kettle connected in series in sequence; the clean waste plastic fragments and the solvent are stirred and mixed in the primary liquefaction kettle and then enter the secondary liquefaction kettle, where they are stirred under anaerobic conditions, and then the solid impurities therein are removed by the solid-liquid separator before entering the tertiary liquefaction kettle;

[0023] The liquefaction temperatures of the first-stage liquefaction kettle, the second-stage liquefaction kettle and the third-stage liquefaction kettle are all 120-280°C; the stirring speeds are all 30-200 rpm; and the residence times are all 10-120 min;

[0024] The mass ratio of the clean waste plastic fragments to the heavy oil is 1:3-20.

[0025] Preferably, in step C), after the filtering, the process further comprises: transporting the filtered liquefied waste plastic to a raw material tank;

[0026] The temperature of the raw material tank is 120-250°C.

[0027] Preferably, in step D), the catalytic cracking unit comprises one or more of a fixed fluidized bed reactor, a riser reactor, a polymerized fluidized bed reactor, a dispersed fluidized bed reactor, a fluidized bed reactor and a turbulent bed reactor;

[0028] The catalytic cracking reaction temperature is 400-680°C and the time is 2-120s;

[0029] The mass ratio of the filtered filtrate to the catalyst is 1:1-15.

[0030] Preferably, in step D), the catalyst comprises one or more of a molecular sieve, a silica-alumina catalyst, a waste FCC catalyst, quartz sand and alumina; the molecular sieve comprises one or more of a Y molecular sieve, a ZSM-5 molecular sieve, a MCM-41 molecular sieve, a mordenite and a SAPO molecular sieve; the silica-alumina catalyst comprises a carrier, a binder and an active component; the carrier is one or more of alumina, silicon oxide, kaolin, diatomaceous earth and montmorillonite; the binder is one or more of alumina sol, pseudo-boehmite, silica sol, silica-alumina sol and phosphate aluminum sol; the active component is one or more of a Y molecular sieve, a ZSM-5 molecular sieve, a MCM-41 molecular sieve, a mordenite, a SAPO molecular sieve and a metal oxide; in the silica-alumina catalyst, the mass content of the carrier is 40% to 70%, and the mass content of the active component is 20% to 40%.

[0031] Preferably, the regeneration operating conditions include: the oxygen volume content of the introduced gas is 20% to 50%; the gas residence time is 5 to 20 seconds; the gas flow rate is 2000 to 10000 m 3 / h; regeneration temperature is 600~700℃.

[0032] The present invention can realize large-scale continuous catalytic cracking of waste plastics, and efficiently convert them into high-value products such as low-carbon olefins, aromatics, gasoline and diesel, thereby realizing high-value recycling of waste plastics; and the treatment process has less pollution to the environment.

[0033] In view of the fact that there are many domestic refineries, which are widely distributed and have huge processing capacity, the present invention combines the chemical recycling of waste plastics with mature oil refining technology, utilizes the existing catalytic cracking unit of the refinery, and uses waste plastics as part of the raw materials of the catalytic cracking unit for "oil-plastic co-refining", catalytically converting waste plastics into small molecular hydrocarbon products under high temperature conditions to produce high value-added products. This technology has the following advantages: reducing the temperature required for the cracking of waste plastics, thereby reducing the energy consumption of the chemical recycling process of waste plastics; accelerating the reaction rate of plastic cracking, promoting the lightweight of cracking products, and optimizing the distribution of cracking products; improving the selectivity of target products, thereby increasing the added value of cracking products. Compared with other treatment methods, catalytic cracking technology can realize the maximum resource utilization of waste plastics, and the treatment process has less pollution to the environment; the obtained products can be used as fuel or chemical raw materials, while realizing the sustainable recycling of waste plastic resources, it can also effectively alleviate the current situation of my country's high dependence on foreign crude oil.

[0034] The present invention can recover waste plastics through multi-point dispersion and carry out clean treatment, and the obtained clean waste plastic fragments are sent to a nearby refinery, and the heavy oil of the refinery is used to dissolve and liquefy them to form a waste plastic liquefied liquid, and the waste plastic liquefied liquid is used as a raw material for the catalytic cracking unit of the refinery for processing. This "oil-plastic co-refining" treatment method can greatly reduce the transportation and treatment costs in the waste plastic recycling process, and reduce the impact of impurities in the waste plastics on the catalytic cracking unit and product quality, thereby realizing large-scale continuous and efficient recycling of waste plastics. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A process flow chart of the present invention for producing high-value products by catalytic cracking of waste plastics and heavy oil;

[0036] Figure 2 A schematic diagram of the structure of a small fixed fluidized bed reactor provided by the present invention;

[0037] Figure 3 The present invention provides a process flow chart for the crushing and waterless cleaning of waste plastics. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The present invention provides a method for producing high-value products by catalytic cracking of mixed waste plastics and heavy oil, comprising the following steps:

[0040] A) After the waste plastics are crushed, they are subjected to anhydrous cleaning treatment to obtain clean waste plastic fragments;

[0041] B) mixing the clean waste plastic fragments with a solvent in a liquefaction unit, heating and liquefying, to obtain waste plastic liquefied liquid and volatile oil gas;

[0042] C) filtering the waste plastic liquefied liquid in a filtering unit;

[0043] D) contacting the filtered filtrate with a fluidized catalyst in a catalytic cracking unit to perform a catalytic cracking reaction to obtain an oil-gas mixture and a catalyst to be produced;

[0044] E) separating the oil-gas mixture into products to obtain dry gas, light olefins, aromatics, gasoline, diesel and heavy oil; the heavy oil is recycled to the liquefaction unit;

[0045] The catalyst to be regenerated is transported to a catalyst regeneration unit and regenerated under aerobic conditions; the regenerated hot catalyst is circulated into the catalytic cracking unit.

[0046] like Figure 1 As shown, Figure 1 The present invention provides a process flow chart for producing high-value products by mixed catalytic cracking of garbage and waste plastics and heavy oil.

[0047] Regarding step A):

[0048] After the waste plastics are crushed, they are treated with anhydrous cleaning to obtain clean waste plastic fragments.

[0049] The waste plastic is preferably garbage waste plastic, selected from one or more of high-density polyethylene, low-density polyethylene, polypropylene, polyvinyl chloride, polystyrene and polyethylene terephthalate; the mass content of polyvinyl chloride in the waste plastic is less than 1.0%. Polyvinyl chloride contains chlorine, and the chlorine in the raw material will generate hydrogen chloride during the catalytic cracking process, causing corrosion to the equipment. Therefore, it is necessary to limit the content of polyvinyl chloride in the raw material.

[0050] In certain embodiments of the present invention, the waste plastics include high-density polyethylene, polypropylene, polyvinyl chloride, and polystyrene; the mass content of high-density polyethylene in the waste plastics is 45%, the mass content of polypropylene is 45%, the mass content of polyvinyl chloride is 0.4%, and the mass content of polystyrene is 9.6%.

[0051] The crushing method may be shredding.

[0052] In certain embodiments of the present invention, the size of the crushed plastic fragments is 0.5 to 5.0 cm, preferably 1.0 to 3.0 cm.

[0053] The waterless cleaning treatment method includes slag removal, hot air drying, gas-solid separation, dust removal and odor removal.

[0054] In certain embodiments of the present invention, the hot air drying temperature is 80-180°C, preferably 110-150°C, such as 130°C.

[0055] In certain embodiments of the present invention, the method of anhydrous cleaning treatment comprises:

[0056] The crushed plastic fragments are subjected to slag removal, hot air drying, gas-solid separation, dust removal and deodorization to obtain clean waste plastic fragments.

[0057] The deslagging is carried out in a deslagging machine. The hot air drying is carried out in a drying machine. The gas-solid separation is carried out using a gas-solid separator. The dust removal is carried out using an electrostatic dust collector. The deodorization is carried out using an activated carbon adsorption device.

[0058] Regarding step B):

[0059] The clean waste plastic fragments are mixed with a solvent in a liquefaction unit, and after heating and liquefaction, waste plastic liquefied liquid and volatile oil gas are obtained.

[0060] In certain embodiments of the present invention, the clean waste plastic fragments are fed into the liquefaction unit via a feeding device. The feeding device is one of a hopper and a screw propeller, preferably a screw propeller. The feeding device uses an inert protective gas to isolate oxygen to prevent the air carried by the waste plastic from entering the subsequent process and causing safety hazards; the inert protective gas can be at least one of nitrogen, helium and argon, preferably nitrogen.

[0061] In certain embodiments of the present invention, the solvent is selected from one or more of heavy oil, light cycle oil, and wax oil. The heavy oil is selected from one or more of atmospheric heavy oil, vacuum gas oil, catalytic cracking heavy oil, hydrocracking heavy oil, and visbroken heavy oil, preferably atmospheric heavy oil. The light cycle oil is one or more of straight-run diesel, catalytic cracking diesel, hydrocracking diesel, and coker diesel; the wax oil is one or more of atmospheric wax oil, vacuum wax oil, and hydrogenated wax oil.

[0062] In certain embodiments of the present invention, the liquefaction unit is a multi-stage liquefaction device, that is, a primary liquefaction kettle, a secondary liquefaction kettle, a solid-liquid separator and a tertiary liquefaction kettle connected in series in sequence. The clean waste plastic fragments and the solvent are stirred and mixed in the primary liquefaction kettle and then enter the secondary liquefaction kettle, where they are stirred under anaerobic conditions, and then the solid impurities therein are removed by the solid-liquid separator before entering the tertiary liquefaction kettle. The liquefaction temperatures of the first-stage liquefaction kettle, the second-stage liquefaction kettle and the third-stage liquefaction kettle are all 120-280°C, preferably 150-250°C, specifically 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C or 250°C, and most preferably 200°C; the stirring rates are all 30-200rpm, preferably 30-60rpm, specifically 30rpm, 40rpm, 50rpm or 60rpm, and most preferably 50rpm; the residence time is all 10-120min, preferably 20-60min, specifically 20min, 30min, 40min, 50min or 60min, and most preferably 30min.

[0063] In certain embodiments of the present invention, the mass ratio of the clean waste plastic fragments to heavy oil is 1:3-20, preferably 1:5-10, specifically 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10, and most preferably 1:5.

[0064] Regarding step C):

[0065] The waste plastic liquefied liquid is filtered in a filtering unit.

[0066] In certain embodiments of the present invention, after the filtering, the process further comprises: transporting the filtered liquefied waste plastic to a raw material tank.

[0067] In certain embodiments of the present invention, the temperature of the raw material tank is 120-250°C, preferably 180-220°C, specifically 180°C, 190°C, 200°C, 210°C or 220°C, most preferably 210°C.

[0068] The raw material tank serves as a temporary reserve to provide raw materials for the subsequent catalytic cracking unit; the limited temperature is due to the fact that the catalytic cracking unit uses liquid phase feed, and the waste plastic liquefied liquid will be solid if not heated, which does not meet the requirements of liquid phase feed.

[0069] Regarding step D):

[0070] The filtered filtrate is contacted with a fluidized catalyst in a catalytic cracking unit to perform a catalytic cracking reaction to obtain an oil-gas mixture and a catalyst to be produced.

[0071] The filtered filtrate can be pumped into a catalytic cracking unit.

[0072] In certain embodiments of the present invention, the catalytic cracking unit is selected from one or more of a fixed fluidized bed reactor, a riser reactor, a polymerized fluidized bed reactor, a dispersed fluidized bed reactor, a boiling bed reactor and a turbulent bed reactor; specifically, a fixed fluidized bed reactor.

[0073] In certain embodiments of the present invention, the catalytic cracking unit comprises:

[0074] A preheating furnace for preheating the filtered waste plastic liquefied liquid;

[0075] A reactor connected to the material outlet of the preheating furnace; a catalyst feed port and a gas-solid separation device are arranged on the top of the reactor;

[0076] a primary condensing device connected to the gas outlet of the gas-solid separation device;

[0077] A liquid collecting device connected to the outlet of the primary condensing device; a first branch is provided on the pipeline between the primary condensing device and the liquid collecting device, the outlet of the first branch is connected to a smoke collecting device for smoke collection; the smoke collecting device is connected to an infrared gas analyzer for smoke analysis and discharge;

[0078] a secondary condensing device connected to the gas outlet of the liquid collecting device;

[0079] a tertiary condensing device connected to the gas outlet of the secondary condensing device;

[0080] A raw material tank connected to the raw material inlet of the preheating furnace; a second branch is provided on the pipeline between the raw material tank and the preheating furnace, and a steam inlet is provided on the second branch; an air supply port is provided at the end of the second branch; the air supply port includes an air supply port and an oxygen supply port;

[0081] A third branch and a fourth branch are arranged on the cracked gas outlet pipeline of the three-stage condensation device; the gas outlet of the third branch is connected to the flue gas collection device; and the gas outlet of the fourth branch is connected to the cracked gas collection device.

[0082] like Figure 2 As shown, Figure 2The present invention provides a schematic diagram of the structure of a small-scale fixed fluidized bed reactor, wherein 1 is an air supply device, 2 is an oxygen supply device, 3-1 is a first gas flow meter, 3-2 is a second gas flow meter, 4 is a water storage tank, 5 is a water inlet pump, 6 is a vaporizer, 7 is a preheating furnace, 8 is a raw material tank, 9 is a raw material pump, 10 is a preheating box, 11 is a high-temperature heating furnace, 12 is a reactor, 13 is a catalyst feed port, 14 is a gas-solid separation device, 15 is a gas outlet of the gas-solid separation device, 16 is a primary condensing device, 17 is a liquid collecting device, 18 is a secondary condensing device, 19 is a refrigeration circulation pump, 20 is a tertiary condensing device, 21 is a flue gas collecting device, 22 is a cracking gas collecting device, 23 is a water collecting tank, 24 is a cracking gas outlet pipeline, 25 is an infrared gas analyzer, 26 is a flue gas outlet, 28 is a No. 1 three-way valve, and 27 is a No. 2 three-way valve.

[0083] In some embodiments of the present invention, the raw material tank 8 is in the preheating box 10, and the outlet of the raw material tank 8 is connected to the inlet of the preheating furnace 7 through the raw material pump 9. A No. 1 three-way valve 28 is arranged between the raw material tank 8 and the preheating furnace 7. When the raw material tank 8 is connected to the preheating furnace 7, the No. 1 three-way valve 28 is in the reaction position. When the raw material tank 8 is not connected to the preheating furnace 7, the raw material tank 8 and the raw material pump 9 are in a closed loop, and at this time, the No. 1 three-way valve 28 is in the reflux position.

[0084] In some embodiments of the present invention, the catalytic cracking unit further comprises: a vaporizer 6; a steam outlet of the vaporizer 6 is connected to a steam inlet on the second branch; and an inlet of the vaporizer 6 is connected to a water storage tank 4 via a water inlet pump 5.

[0085] In certain embodiments of the present invention, the three-stage condensing device 20 is equipped with a refrigeration circulation pump 19 .

[0086] In certain embodiments of the present invention, a valve is provided at the end of the cracked gas outlet pipeline 24 of the three-stage condensation device 20. A valve is provided between the gas outlet of the third branch and the flue gas collection device 21. A valve is provided between the gas outlet of the fourth branch and the cracked gas collection device 22.

[0087] In some embodiments of the present invention, a fifth branch is provided on the cracked gas outlet pipeline 24 of the three-stage condensation device 20; the gas outlet of the fifth branch is connected to the infrared gas analyzer 25. A valve is provided between the gas outlet of the fifth branch and the infrared gas analyzer 25.

[0088] The cracked gas outlet pipeline 24 is used for gas sampling and analysis and cracked gas discharge.

[0089] In some embodiments of the present invention, the air supply port of the second branch is connected to the air supply device 1. A first gas flow meter 3-1 is provided at the outlet of the air supply device 1. The air supply device 1 may be an air pump.

[0090] In some embodiments of the present invention, the oxygen supply port of the second branch is connected to an oxygen supply device. A second gas flow meter 3-2 is arranged at the outlet of the oxygen supply device 2.

[0091] In some embodiments of the present invention, a No. 2 three-way valve 27 is provided at the intersection of the pipeline between the primary condensing device and the liquid collecting device and the first branch. During regeneration, the No. 2 three-way valve 27 is switched to the first branch, and the generated flue gas enters the flue gas collecting device 21; during flue gas analysis, the valve on the line between the flue gas collecting device 21 and the infrared gas analyzer 25 is opened for sampling and analysis.

[0092] Before starting the catalytic cracking unit for heating, a certain amount of catalyst is loaded into the reactor 12, and then the air pump 1 is turned on, and the catalyst in the reactor 12 is fluidized using air as a fluidizing carrier gas. When the temperature of the reactor 12 and the vaporizer 6 reaches 200-350°C, the air pump 1 is turned off and the water pump 5 is turned on, and the fluidizing carrier gas is switched from air to water vapor, and the catalyst in the reactor 12 is fluidized using water vapor, and then the temperature is continued to rise. When the temperature in the reactor 12 reaches 400-680°C, the No. 1 three-way valve in front of the preheating furnace 7 is placed in the reflux position, and the raw material pump 9 is turned on for reflux, so that the raw material circulates in the pipeline at the front end of the preheating furnace 7 to avoid experimental errors caused by the raw material not filling the feed pipeline. After the reflux is completed, the No. 1 three-way valve in front of the preheating furnace 7 is switched to the reaction position, and then the raw material pump 9 is turned on, and the raw material in the preheating box 10 and the water vapor vaporized by the vaporizer 6 pass through the preheating furnace 7 into the reactor 12. The products generated by the reaction are taken out of the reactor 12 by water vapor, and separated into gas and liquid products through the gas outlet 15 of the gas-solid separation device, the primary condensation device 16, the secondary condensation device 18 and the tertiary condensation device 20. The condensed liquid products and condensed water are returned to the liquid collection device 17 for collection, and the gas products are collected in the cracked gas collection device 22, and the gas products are sampled and analyzed from the cracked gas outlet 24. After the reaction is completed, the reactor 12 is heated, and at the same time, the cracked products remaining on the catalyst surface and in the reactor 12 are stripped by water vapor. When the temperature of the reactor 12 reaches the set regeneration temperature of 600-680°C, the water inlet pump 5 is turned off, and the oxygen supply device 2 is turned on to start the regeneration process. The flue gas enters the flue gas collection device 21 for collection, and is analyzed by the infrared gas analyzer 25, and then discharged from the flue gas outlet 26.

[0093] In certain embodiments of the present invention, the temperature of the catalytic cracking reaction is 400-680°C, preferably 500-650°C, specifically 500°C, 550°C, 600°C or 650°C, most preferably 600°C; the reaction time is 2-120s, preferably 20-60s, specifically 20s, 30s, 40s, 50s or 60s, most preferably 40s.

[0094] In certain embodiments of the present invention, the mass ratio of the filtered filtrate to the catalyst is 1:1-15, preferably 1:1-8, specifically 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7 or 1:8, most preferably 1:5.

[0095] In certain embodiments of the present invention, the catalyst is selected from one or more of molecular sieves, silicon-alumina catalysts, waste FCC catalysts, quartz sand and alumina. The molecular sieve is selected from one or more of Y molecular sieve, ZSM-5 molecular sieve, MCM-41 molecular sieve, mordenite and SAPO molecular sieve. The silica-alumina material catalyst comprises a carrier, a binder and an active component; the carrier is one or more of alumina, silica, kaolin, diatomaceous earth and montmorillonite; the binder is one or more of alumina sol, pseudo-boehmite, silica sol, silica-alumina sol and phosphate aluminum sol; the active component is one or more of Y molecular sieve, ZSM-5 molecular sieve, MCM-41 molecular sieve, mordenite, SAPO molecular sieve and metal oxide; in the silica-alumina material catalyst, the mass content of the carrier is 40% to 70%, specifically 40%, 45%, 50%, 55%, 60%, 65% or 70%, and most preferably 50%; in the catalyst, the mass content of the active component is 20% to 40%, specifically 20%, 25%, 30%, 35% or 40%, and most preferably 35%.

[0096] Regarding step E):

[0097] The oil-gas mixture is subjected to product separation to obtain dry gas, light olefins, aromatics, gasoline, diesel and heavy oil; the heavy oil is recycled to the liquefaction unit;

[0098] The catalyst to be regenerated is transported to a catalyst regeneration unit and regenerated under aerobic conditions; the regenerated hot catalyst is circulated into the catalytic cracking unit.

[0099] In certain embodiments of the present invention, the catalyst regeneration unit is a fluidized bed regenerator.

[0100] In certain embodiments of the present invention, the regeneration operating conditions include: the oxygen volume content of the introduced gas is 20% to 50%, preferably the gas is air; the gas residence time is preferably 5 to 20 seconds, specifically 5 seconds, 10 seconds, 15 seconds, or 20 seconds, most preferably 10 seconds; the gas flow rate is preferably 2000 to 10000 m 3 / h, specifically 2000m 3 / h、3000m 3 / h、4000m 3 / h、5000m 3 / h、6000m 3 / h、7000m 3 / h、8000m 3 / h、9000m 3 / h or 10000m 3 / h, the most preferred is 8000m 3 The regeneration temperature is 600-700°C, specifically 600°C, 620°C, 640°C, 660°C, 680°C or 700°C, and most preferably 620°C.

[0101] Preferably, the regeneration is performed in the presence of oxygen and dry gas. Specifically, during the regeneration process, part of the dry gas enters the regeneration unit, so that the catalyst to be regenerated undergoes a complete combustion reaction in the presence of oxygen and dry gas to obtain a regenerated catalyst.

[0102] In certain embodiments of the present invention, the product separation method includes but is not limited to one or more of gas-liquid separation, extraction separation, adsorption separation and distillation; the separated products include but are not limited to high-value products such as light olefins, aromatics, gasoline, diesel and heavy oil.

[0103] The present invention utilizes waterless cleaning treatment to greatly improve the pretreatment efficiency and impurity removal efficiency of waste plastics, reduce water consumption and reduce the cost of the waste plastic cleaning process.

[0104] The present invention performs liquefaction treatment on waste plastics to obtain waste plastic liquefied liquid that meets the liquid phase feed of a downstream catalytic cracking device, and can realize large-scale continuous catalytic cracking of waste plastics.

[0105] The method provided by the present invention adopts the "oil-plastic co-refining" approach, and utilizes a series of process flows such as shredding and anhydrous cleaning treatment, liquefaction treatment, catalytic cracking and product separation, so as to realize large-scale continuous production of high-value products such as low-carbon olefins, aromatics, gasoline and diesel from waste plastics, thereby realizing high-value recycling of waste plastics.

[0106] The present invention solves the environmental pollution caused by garbage and waste plastics while reducing the recycling cost thereof, thereby realizing the resource conversion and efficient recycling of garbage and waste plastics.

[0107] The present invention has no particular limitation on the sources of the raw materials used above, and they can be generally commercially available.

[0108] In order to further illustrate the present invention, a method for producing high-value products by mixed catalytic cracking of waste plastics and heavy oil provided by the present invention is described in detail below in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0109] Example

[0110] A method for producing high-value products by catalytic cracking of waste plastics and heavy oil, such as Figure 1 As shown:

[0111] 1) The waste plastics include high-density polyethylene, polypropylene, polyvinyl chloride, and polystyrene; the mass content of high-density polyethylene in the waste plastics is 45%, the mass content of polypropylene is 45%, the mass content of polyvinyl chloride is 0.4%, and the mass content of polystyrene is 9.6%;

[0112] The waste plastics are shredded into 1-3 cm plastic fragments by a double-axis roller-cutting pulverizer, and the plastic fragments are transported to the air separation and impurity removal system by a conveyor; in the air separation and impurity removal system, the plastic fragments are removed by a slag remover to remove solid impurities such as sand, metal, and wood chips in the waste plastics; the waste plastic fragments are then dried by a dryer with 130°C hot air, and the moisture is separated in the form of water vapor to obtain dry waste plastic fragments, which enter the gas-solid separation system (the equipment used for gas-solid separation is a gas-solid separator); the waste plastic fragments are sent to the screw propeller feeding device through the distribution valve at the bottom of the gas-solid separation system; the separated gas is sent to the dust removal and odor removal system (electrostatic precipitator and activated carbon adsorption device) through an induced draft fan, and discharged into the atmosphere through an exhaust pipe after treatment. Figure 3 shown. Figure 3 The present invention provides a process flow chart for the crushing and waterless cleaning of waste plastics.

[0113] After testing, the drying efficiency of waste plastics was 96.6% and the impurity removal rate was 95.2%.

[0114] 2) The liquefaction unit comprises a primary liquefaction kettle, a secondary liquefaction kettle, a solid-liquid separator and a tertiary liquefaction kettle which are connected in series in sequence.

[0115] The clean waste plastic fragments delivered from the screw propeller feeding device are fully stirred and mixed with atmospheric heavy oil in the first-stage liquefaction kettle, the mass ratio of the waste plastic fragments to the atmospheric heavy oil is 1:4, the liquefaction temperature is 200°C, the stirring rate is 50rpm, and the residence time is 30min; then enter the second-stage liquefaction kettle, stir under the condition of nitrogen as a protective gas, and then enter the third-stage liquefaction kettle after removing the solid impurities therein through the solid-liquid separator; the operating conditions (liquefaction temperature, stirring rate, residence time) of the second-stage liquefaction kettle and the third-stage liquefaction kettle are the same as those of the first-stage liquefaction kettle. The properties of the obtained waste plastic liquefied liquid are shown in Table 1.

[0116] Table 1 Properties of waste plastic liquefied liquid

[0117] nature Waste plastic liquefaction <![CDATA[Density (25 °C), g / cm 3 > 0.9206 Ash, wt.% 5.12 Acid value, mgKOH / g 1.39 Distillation range, wt.% IBP-180℃ - 180-350℃ 4.7 ＞350℃ 95.3 Impurity content, mg / L Cl 1904.32 S 1696.72 N 518.29 Metal element content, μg / g Ca 2579.59 Cu 24.90 Fe 1288.75 Mg 306.36 Ni 3.26 Si 762.58

[0118] Through analysis, it can be seen that the liquefaction rate of waste plastics during the liquefaction process is 98.3%.

[0119] 3) filtering the waste plastic liquefied liquid in a filtering unit; and conveying the filtered waste plastic liquefied liquid to a raw material tank. The temperature of the raw material tank is 210°C.

[0120] 4) contacting the waste plastic liquefied liquid in the raw material tank with the fluidized catalyst in a catalytic cracking unit to perform a catalytic cracking reaction to obtain an oil-gas mixture and a catalyst to be produced;

[0121] The catalytic cracking unit is Figure 2 As shown, including:

[0122] A preheating furnace 7 for preheating the filtered waste plastic liquefied liquid;

[0123] A reactor 12 connected to the material outlet of the preheating furnace 7; a catalyst feed port 13 and a gas-solid separation device 14 are arranged on the top of the reactor 12;

[0124] A primary condensing device 16 connected to the gas outlet 15 of the gas-solid separation device;

[0125] A liquid collecting device 17 connected to the outlet of the primary condensing device 16; a first branch is provided on the pipeline between the primary condensing device 16 and the liquid collecting device 17, the outlet of the first branch is connected to a smoke collecting device 21 for smoke collection; the smoke collecting device 21 is connected to an infrared gas analyzer 25 for smoke analysis and discharge;

[0126] a secondary condensation device 18 connected to the gas outlet of the liquid collecting device 17;

[0127] a tertiary condensation device 20 connected to the gas outlet of the secondary condensation device 18;

[0128] A raw material tank 8 connected to the raw material inlet of the preheating furnace 7; a second branch is provided on the pipeline between the raw material tank 8 and the preheating furnace 7, and a steam inlet is provided on the second branch; an air supply port is provided at the end of the second branch; the air supply port includes an air supply port and an oxygen supply port;

[0129] A third branch and a fourth branch are provided on the cracked gas outlet pipeline of the three-stage condensation device 20; the gas outlet of the third branch is connected to the flue gas collecting device 21; the gas outlet of the fourth branch is connected to the cracked gas collecting device 22;

[0130] The raw material tank 8 is in the preheating box 10, and the outlet of the raw material tank 8 is connected to the inlet of the preheating furnace 7 through the raw material pump 9; a No. 1 three-way valve 28 is arranged between the raw material tank 8 and the preheating furnace 7; when the raw material tank 8 is connected to the preheating furnace 7, the No. 1 three-way valve 28 is in the reaction position; when the raw material tank 8 is not connected to the preheating furnace 7, the raw material tank 8 and the raw material pump 9 are in a closed loop, and at this time, the No. 1 three-way valve 28 is in the reflux position;

[0131] The vaporizer 6; the steam outlet of the vaporizer 6 is connected to the steam inlet on the second branch; the inlet of the vaporizer 6 is connected to the water storage tank 4 through the water inlet pump 5;

[0132] The three-stage condensing device 20 is equipped with a refrigeration circulation pump 19;

[0133] A valve is provided at the end of the cracked gas outlet pipeline 24 of the three-stage condensation device 20; a valve is provided between the gas outlet of the third branch and the flue gas collecting device 21; a valve is provided between the gas outlet of the fourth branch and the cracked gas collecting device 22;

[0134] A fifth branch is provided on the cracked gas outlet pipeline 24 of the three-stage condensation device 20; the gas outlet of the fifth branch is connected to the infrared gas analyzer 25; a valve is provided between the gas outlet of the fifth branch and the infrared gas analyzer 25;

[0135] The air supply port of the second branch is connected to the air supply device 1; a first gas flow meter 3-1 is provided at the outlet of the air supply device 1; the air supply device 1 may be an air pump;

[0136] The oxygen supply port of the second branch is connected to the oxygen supply device; a second gas flow meter 3-2 is provided at the outlet of the oxygen supply device 2;

[0137] A No. 2 three-way valve 27 is provided at the intersection of the pipeline between the primary condensing device and the liquid collecting device and the first branch.

[0138] The catalytic cracking catalyst (S) is composed of a carrier, a binder and an active component. The catalyst carrier is alumina and kaolin, accounting for 35% and 20% of the total mass of the catalyst respectively; the binder is silica-alumina sol, accounting for 10% of the total mass of the catalyst; and the active component is ZSM-5 molecular sieve, accounting for 35% of the total mass of the catalyst.

[0139] The catalytic cracking reaction conditions of the waste plastic liquefied liquid are shown in Table 2; the commercial catalytic cracking catalyst (reference agent, D) produced by Sinopec Petrochemical Research Institute Co., Ltd. and the above-mentioned catalytic cracking catalyst (S) were used to catalytically crack the waste plastic liquefied liquid, and the distribution comparison of the cracking products is shown in Table 3.

[0140] Table 2 Catalytic cracking reaction conditions of waste plastic liquefaction liquid

[0141] project data Catalyst loading, g 200 Raw material feed amount, g 40 Carburetor temperature, °C 150 Feed line and circulation line temperature, ℃ 130 Vaporization furnace temperature, °C 300 Preheating furnace temperature, °C 250 Reactor temperature, °C 500 Stripping time, min 40 First condensation temperature, °C 35 Secondary condensation temperature, °C -10 Secondary condensation temperature, °C -10 Regeneration temperature, °C 620 Regeneration time, min 30 Pump mass flow rate, g / min 3.0 Air inlet pressure, MPa 0.4 Air flow, L / min 3 Oxygen inlet pressure, MPa 0.4 Oxygen flow rate, L / min 1

[0142] Table 3 Distribution of catalytic cracking products of waste plastic liquefaction liquid

[0143] Fraction yield / wt.% Reference Agent D Catalyst S Dry gas 4.28 3.08 Liquefied gas 25.49 39.39 gasoline 40.00 47.19 diesel fuel 17.65 1.99 heavy oil 3.32 0.68 Coke 7.54 5.86 Light olefins 16.04 21.15 Aromatics 8.51 32.08 Light fuel oil 60.97 49.18 Oil and gas yield 92.46 94.14 Conversion rate 98.28 98.18

[0144] From the above experiments, it can be seen that the present invention adopts the "oil-plastic co-refining" method to realize large-scale continuous industrial production of waste plastics into high-value products such as low-carbon olefins, aromatics, gasoline and diesel, thereby realizing high-value recycling of waste plastics.

[0145] Compared with the reference agent, the catalyst used in the present invention can significantly increase the yield of light olefins, aromatics, gasoline fractions and oil and gas yields, and reduce the yield of heavy oil fractions and coke; in addition, the cracking conversion rate of waste plastics is above 98%.

[0146] The description of the above embodiments is only used to help understand the method of the present invention and its core idea. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features disclosed herein.

Claims

1. A method for producing high-value products by catalytic cracking of waste plastics and heavy oil, comprising the following steps: A) After the waste plastics are crushed, they are subjected to anhydrous cleaning treatment to obtain clean waste plastic fragments; B) mixing the clean waste plastic fragments with a solvent in a liquefaction unit, heating and liquefying, to obtain a waste plastic liquefied liquid; C) filtering the waste plastic liquefied liquid in a filtering unit; D) contacting the filtered filtrate with a fluidized catalyst in a catalytic cracking unit to perform a catalytic cracking reaction to obtain an oil-gas mixture and a catalyst to be produced; E) separating the oil-gas mixture into products to obtain dry gas, light olefins, aromatics, gasoline, diesel and heavy oil; the heavy oil is recycled to the liquefaction unit; The catalyst to be regenerated is transported to a catalyst regeneration unit and regenerated under aerobic conditions; the regenerated hot catalyst is circulated into the catalytic cracking unit.

2. The method according to claim 1, characterized in that The waste plastics are garbage waste plastics, including one or more of high-density polyethylene, low-density polyethylene, polypropylene, polyvinyl chloride, polystyrene and polyethylene terephthalate; the mass content of polyvinyl chloride in the waste plastics is less than 1.0%.

3. The method according to claim 1, characterized in that The size of the crushed plastic fragments is 0.5 to 5.0 cm; The waterless cleaning treatment method includes slag removal, hot air drying, gas-solid separation, dust removal and odor removal; The temperature of the hot air drying is 80-180°C.

4. The method according to claim 1, characterized in that: The clean waste plastic fragments are fed into the liquefaction unit via a feeding device; the feeding device comprises one of a hopper and a screw propeller; The feeding device uses an inert protective gas to isolate oxygen; the inert protective gas includes at least one of nitrogen, helium and argon.

5. The method according to claim 1, characterized in that The solvent includes one or more of heavy oil, light cycle oil and wax oil; The heavy oil includes one or more of atmospheric heavy oil, vacuum gas oil, catalytic cracking heavy oil, hydrocracking heavy oil and visbroken heavy oil; The light cycle oil includes one or more of straight-run diesel, catalytic cracking diesel, hydrocracked diesel and coker diesel; The wax oil includes one or more of atmospheric wax oil, vacuum wax oil and hydrogenated wax oil.

6. The method according to claim 1, characterized in that The liquefaction unit comprises a primary liquefaction kettle, a secondary liquefaction kettle, a solid-liquid separator and a tertiary liquefaction kettle connected in series in sequence; the clean waste plastic fragments and the solvent are stirred and mixed in the primary liquefaction kettle and then enter the secondary liquefaction kettle, where they are stirred under anaerobic conditions, and then the solid impurities therein are removed by the solid-liquid separator before entering the tertiary liquefaction kettle; The liquefaction temperatures of the first-stage liquefaction kettle, the second-stage liquefaction kettle and the third-stage liquefaction kettle are all 120-280°C; the stirring speeds are all 30-200 rpm; and the residence times are all 10-120 min; The mass ratio of the clean waste plastic fragments to the heavy oil is 1:3-20.

7. The method according to claim 1, characterized in that In step C), after the filtering, the method further comprises: transporting the filtered liquefied waste plastic to a raw material tank; The temperature of the raw material tank is 120-250°C.

8. The method according to claim 1, characterized in that In step D), the catalytic cracking unit comprises one or more of a fixed fluidized bed reactor, a riser reactor, a polymerized fluidized bed reactor, a dispersed fluidized bed reactor, a fluidized bed reactor and a turbulent bed reactor; The catalytic cracking reaction temperature is 400-680°C and the time is 2-120s; The mass ratio of the filtered filtrate to the catalyst is 1:1-15.

9. The method according to claim 1, characterized in that: In step D), the catalyst comprises one or more of a molecular sieve, a silica-alumina catalyst, a waste FCC catalyst, quartz sand and alumina; the molecular sieve comprises one or more of a Y molecular sieve, a ZSM-5 molecular sieve, a MCM-41 molecular sieve, a mordenite and a SAPO molecular sieve; the silica-alumina catalyst comprises a carrier, a binder and an active component; the carrier is one or more of alumina, silicon oxide, kaolin, diatomaceous earth and montmorillonite; the binder is one or more of alumina sol, pseudo-boehmite, silica sol, silica-alumina sol and phosphate aluminum sol; the active component is one or more of a Y molecular sieve, a ZSM-5 molecular sieve, a MCM-41 molecular sieve, a mordenite, a SAPO molecular sieve and a metal oxide; in the silica-alumina catalyst, the mass content of the carrier is 40% to 70%, and the mass content of the active component is 20% to 40%.

10. The method according to claim 1, characterized in that The regeneration operating conditions include: the oxygen volume content of the introduced gas is 20% to 50%; the gas residence time is 5 to 20 seconds; the gas flow rate is 2000 to 10000 m 3 / h; regeneration temperature is 600~700℃.

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