Processing method and processing system for waste plastic fluidization cracking

Abstract

The invention relates to a waste plastic fluidized cracking processing method and system, and the method comprises the following steps: S1, enabling a plastic raw material to enter first heating and conveying equipment, and carrying out liquefaction treatment to obtain liquefied plastic; s2, the liquefied plastic and a dechlorination additive enter a visbreaking reactor to be subjected to visbreaking reaction and dechlorination, and liquefied plastic oil and first dry gas are obtained; s3, the liquefied plastic oil enters a contact cracking reactor and makes contact with a regeneration contact agent for a cracking reaction under the condition of a dilute-phase fluidized bed, and reaction oil gas, a spent contact agent and charcoal-containing ash are obtained; s4, the charcoal-containing ash and the spent contact agent enter a contact agent regenerator and react with oxygen for scorching regeneration, and a regenerated contact agent, regenerated flue gas and ash are obtained; s5, recycling the ash content as a dechlorination additive; s6, the reaction oil gas enters a separation unit to be separated, and second dry gas, liquefied gas, gasoline fraction, diesel fraction and wax oil fraction are obtained. According to the invention, waste plastic resource utilization is realized.

Description

Technical Field

[0001] The present disclosure relates to the field of waste plastic resource recycling, and in particular to a processing method and a processing system for fluidized cracking of waste plastic. Background Art

[0002] With the advancement of science and technology and industrial development, plastics are now widely used as packaging materials in our daily lives. However, used plastic waste cannot decompose naturally, and only a few types of waste plastic can be reprocessed and reused through specific recycling channels. A large amount of waste plastic ends up in landfills as household waste. Because waste plastics are difficult to decompose, they occupy a significant amount of space. The rapid increase in waste plastic generation in recent years has made the rapid and environmentally friendly recycling of waste plastics an urgent task.

[0003] The simplest way to dispose of waste plastics is direct incineration, but this produces toxic gases harmful to humans and causes secondary environmental pollution. Waste plastic pyrolysis technology involves cracking waste plastics in the absence or absence of oxygen by heating or in the presence of a catalyst, breaking down high polymers into low-molecular-weight substances. These products produce gasoline, kerosene, diesel fractions, and some pyrolysis gases. This technology alleviates the pollution caused by waste plastics while enabling their recycling, making it a key area of waste plastic resource recovery.

[0004] At present, waste plastic cracking and recycling technologies mainly include waste plastic pyrolysis and catalytic pyrolysis technologies. CN201710726352.9 discloses a method and equipment for preparing gasoline and diesel by cracking waste plastics. The system dissolves the crushed and impurity-removed waste plastics in liquid pyrolysis oil, and performs melting, dehydration, dechlorination, cracking and quality improvement through precise temperature control. The process requires a large amount of solvent oil. For example, CN200780003589.9 discloses a method and device for contact decomposition of waste plastics, which belongs to catalytic pyrolysis technology. A heated and stirred rotary kiln is used as a reactor, an FCC catalyst is used as a heat medium and a catalytic center, and an appropriate amount of Ca and Fe compounds are added to decompose the waste plastics. However, after the device has been operated for a period of time, the contact agent in the reactor needs to be removed and regenerated. More waste plastic cracking technologies use intermittent thermal cracking reactors. This type of method has the problem of small processing scale, and impurities in the product cannot be removed. Summary of the Invention

[0005] The technical problem solved by the present invention is to provide a fluidized cracking processing method and processing system for waste plastics, which can continuously perform fluidized cracking on plastic raw materials, realize the effective utilization of waste plastic resources, and effectively remove impurities in the products.

[0006] In a first aspect, the present disclosure provides a method for processing waste plastics by fluidized cracking, comprising the following steps:

[0007] S1, the plastic raw material enters the first heating and liquefaction conveying equipment for liquefaction treatment to obtain liquefied plastic;

[0008] S2, the liquefied plastic and the dechlorination additive enter the visbreaking reactor to undergo visbreaking reaction and dechlorination to obtain liquefied plastic oil and the first dry gas;

[0009] S3, the liquefied plastic oil enters the contact cracking reactor, and contacts with the high-temperature contact agent under the condition of a dilute phase fluidized bed to carry out a cracking reaction, thereby obtaining reaction oil gas, the spent contact agent and the carbon ash;

[0010] S4, the regenerated contact agent and the ash with carbon enter the contact agent regenerator, react with oxygen and burn to regenerate, and obtain regenerated contact agent, regenerated flue gas and ash;

[0011] S5. Part or all of the ash is recycled to the visbreaking reactor as a dechlorination additive;

[0012] S6. The reaction oil and gas enter the separation unit for separation to obtain a second dry gas, liquefied gas, gasoline fraction, diesel fraction and wax oil fraction.

[0013] The regenerated contact agent is returned to the contact cracking reactor for continued use.

[0014] Optionally, before step S1, the method further includes: the plastic raw material enters the second heating and conveying equipment, is melted and dehydrated at a first temperature to obtain a dehydrated plastic raw material; the dehydrated plastic raw material is heated to a second temperature for dechlorination treatment to obtain a dehydrated and dechlorinated plastic raw material and hydrogen chloride-containing gas; and the dehydrated and dechlorinated plastic raw material is directly entered into the first heating and conveying equipment for liquefaction treatment.

[0015] Preferably, the dehydrated and dechlorinated plastic raw material is sequentially cooled and pulverized in a cooling and pulverizing unit to obtain dehydrated and dechlorinated plastic raw material particles; the dehydrated and dechlorinated plastic raw material particles are then fed into a first heating and conveying device for liquefaction. Optionally, the particle size of the plastic raw material particles is 0.5 mm to 10 mm.

[0016] Optionally, the method further comprises: the hydrogen chloride-containing gas contacts a hydrogen chloride absorbent to remove hydrogen chloride; the hydrogen chloride absorbent is water or an alkaline solution with a pH value greater than 7; optionally, the alkaline solution is selected from one or more of sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution, sodium bicarbonate solution, sodium carbonate solution and ammonia water.

[0017] Optionally, in step S4, the method further includes: at least part of the first dry gas and / or at least part of the second dry gas enters the contact agent regenerator, so that the regenerated contact agent and the carbon-containing ash undergo a complete combustion reaction in the presence of oxygen and dry gas to obtain regenerated contact agent, regenerated flue gas and ash and regenerated flue gas; preferably, based on the total weight of the regenerated contact agent, the carbon content of the regenerated contact agent is 0.5% to 5.0% by weight.

[0018] Optionally, in step S1, the first heating and conveying equipment is a screw heating and conveying equipment; preferably, the screw heating and conveying equipment is selected from a twin-screw or single-screw conveying equipment with heating; preferably, the process conditions of the liquefaction treatment include: an outlet temperature of 380°C to 500°C, preferably 400°C to 450°C; a residence time of 5min to 30min, preferably 5min to 15min.

[0019] Optionally, in step S2, the visbreaking reactor is an adiabatic visbreaking reactor;

[0020] Preferably, the process conditions of the visbreaking reaction include: a reaction temperature of 360° C. to 490° C., preferably 370° C. to 420° C.; and a residence time of 10 min to 90 min, preferably 20 min to 60 min.

[0021] Optionally, in step S3, the process conditions of the cracking reaction include: a reaction temperature of 490° C. to 750° C., an apparent gas velocity of the dilute phase fluidized bed of 0.3 to 8.0 m / s, and a mass ratio of the contact agent to the plastic raw material of 5 to 30:1; preferably, the reaction temperature is 500° C. to 650° C., an apparent gas velocity of the dilute phase fluidized bed of 1.0 to 6.0 m / s, and a mass ratio of the contact agent to the plastic raw material of 6 to 20:1;

[0022] Preferably, steam is allowed to enter the contact cracking reactor; the mass ratio of steam to plastic raw material is 0.05 to 1:1, more preferably 0.1 to 0.5:1.

[0023] Optionally, in step S3, the contact agent is selected from one or more of silicon-aluminum material, quartz sand or coal coke powder; preferably, the particle size of the contact agent is 50 μm to 240 μm;

[0024] Optionally, the silicon-aluminum material contains molecular sieves or does not contain molecular sieves; wherein the molecular sieve is one or more selected from X molecular sieve, Y molecular sieve, mordenite, ZSM-5, pillared clay molecular sieve and SAPO;

[0025] Among them, the silicon-aluminum material without molecular sieve is a catalyst prepared with one or more of the first raw materials as raw materials, and the first raw materials include amorphous silicon-aluminum, kaolin, montmorillonite, rectorite, illite, chlorite, pseudo-boehmite and silica; or the silicon-aluminum material without molecular sieve is selected from a catalyst prepared with one or more of the second raw materials that have been pickled, calcined and sieving as raw materials, and the second raw materials include amorphous silicon-aluminum, kaolin, montmorillonite, rectorite, illite and chlorite; or it is selected from a catalyst prepared with one or more of the second raw materials that have been pickled, calcined and sieving and pseudo-boehmite and / or silica as raw materials; optionally, the coal coke powder is coal powder and / or petroleum coke powder.

[0026] Optionally, in step S4, the charring regeneration treatment of the regenerated contact agent is carried out in a contact agent regenerator; the contact agent regenerator adopts a dense fluidized bed regenerator, and the process conditions include: a residence time of 0.5 seconds to 60 seconds, preferably 1.0 seconds to 10 seconds; a regeneration temperature of 600°C to 750°C, preferably 600°C to 700°C; air or a mixture of air and inert gas is introduced; the superficial gas velocity of the dense fluidized bed is 0.05m / s to 0.6m / s, preferably 0.2m / s to 0.4m / s.

[0027] Optionally, in step S5, the weight ratio of the dechlorination additive to the liquefied plastic is (0.025-0.045):1, preferably (0.03-0.04):1. The dechlorination additive is an externally added alkaline metal compound and / or ash from a contact agent regenerator. Preferably, the dechlorination additive is ash from a contact agent regenerator.

[0028] Optionally, the second heating and conveying equipment includes a screw heating and conveying equipment and a vacuum device connected to the screw heating and conveying equipment; preferably, the screw heating and conveying equipment is selected from a twin-screw or single-screw conveying equipment with heating; preferably, the process conditions of the second heating and conveying equipment include: the first temperature is 120℃~150℃; the residence time is 0.05h~0.5h; the second temperature is 220℃~350℃; the residence time is 0.1h~0.2h; the vacuum degree is 50mmHg~300mmHg, preferably 50mmHg~150mmHg; preferably, the heating rate from the first temperature to the second temperature is 50℃ / min~200℃ / min, more preferably 50℃ / min~150℃ / min.

[0029] Optionally, the plastic raw material is selected from one or more of LDPE, HDPE, PS, PP, PET and PVC; optionally, the chlorine content in the plastic raw material is less than 10 weight %; the ash content in the plastic raw material is 1 weight % to 40 weight %, preferably 3 weight % to 20 weight %.

[0030] In a second aspect, the present disclosure provides a processing system for fluidized cracking of waste plastics, comprising a first heating and liquefying conveying device, a visbreaking reactor, a contact cracking reactor, a separation unit and a contact agent regenerator connected in sequence; the first heating and liquefying conveying device comprises a raw material inlet and a liquefied plastic outlet, and the first heating and liquefying conveying device is configured to liquefy the plastic raw material; the plastic visbreaking reactor comprises a liquefied plastic inlet, a dechlorination additive inlet, a liquefied plastic oil outlet and a first dry gas outlet, and the plastic visbreaking reactor is configured to perform visbreaking on the liquefied plastic; the contact cracking reactor comprises a cracking raw material inlet, a contact agent inlet, a reaction oil and gas outlet and a contact agent outlet to be regenerated; the cracking raw material inlet and the liquefied plastic of the plastic visbreaking reactor are connected in series. The feed oil outlet is connected, and the contact cracking reactor is configured to perform cracking reaction treatment on the liquefied plastic oil; the separation unit includes a reaction oil and gas inlet, a second dry gas outlet, a liquefied gas outlet, a gasoline fraction outlet, a diesel fraction outlet and a wax oil fraction outlet; the separation unit is configured to separate the reaction oil and gas; the dense phase fluidized bed regenerator includes a regenerated contact agent inlet, an oxygen-containing gas inlet, a regenerated contact agent outlet, an ash outlet and a regenerated flue gas outlet; the dense phase fluidized bed regenerator is configured to react the regenerated contact agent with oxygen to perform char regeneration to obtain a regenerated contact agent and a regenerated flue gas; the regenerated contact agent outlet is connected to the contact agent inlet of the contact cracking reactor; the ash outlet is connected to the dechlorination additive inlet of the visbreaking reactor.

[0031] Preferably, the dense phase fluidized bed regenerator further comprises a dry gas inlet, which is connected to the first dry gas outlet of the visbreaking reactor and / or the second dry gas outlet of the separation unit.

[0032] Optionally, the connecting pipeline between the cracking feedstock inlet of the contact cracking reactor and the liquefied plastic oil outlet of the visbreaking reactor further includes a steam inlet.

[0033] Optionally, the processing system further includes a second heating and conveying device, a hydrogen chloride absorption unit and a cooling and crushing unit that are connected in sequence before the first heating and liquefying conveying device; the second heating and liquefying conveying device includes a raw material inlet, a dehydrated and dechlorinated plastic outlet and a hydrogen chloride-containing gas outlet; the second heating and liquefying conveying device is configured to perform melting, dehydration and dechlorination treatments on the chlorine-containing waste plastic; the cooling and crushing unit is configured to perform cooling and crushing treatments on the dehydrated and dechlorinated plastic from the second heating and liquefying conveying device; the hydrogen chloride absorption unit includes a gas inlet and a hydrogen chloride absorbent; the gas inlet is connected to the hydrogen chloride-containing gas outlet of the second heating and liquefying conveying device.

[0034] Preferably, the hydrogen chloride absorption unit is connected to a vacuum device.

[0035] Preferably, the first heating conveying device is a screw-type heating conveying device; preferably, the screw-type heating conveying device is selected from a single-screw or twin-screw conveying device with heating;

[0036] Preferably, the second heating and conveying device is a screw-type heating and conveying device; preferably, the screw-type heating and conveying device is selected from a single-screw or twin-screw conveying device with heating.

[0037] Through the above technical solution, the present disclosure provides a processing method and processing system for fluidized cracking of waste plastics, which subject plastic raw materials to liquefaction and visbreaking treatment, thereby enabling the waste plastics to be rapidly liquefied and reducing their viscosity; and using ash produced by a contact agent regenerator as a dechlorination additive in a visbreaking reactor for further dechlorination, which is then contacted with a fluidized contact agent for cracking reaction, thereby enabling the waste plastics to be processed to be rapidly pyrolyzed in liquid form in contact with the high-temperature contact agent, thereby reducing the residence time of the products and obtaining a more ideal product distribution, and removing heteroatoms from the plastic raw materials; by producing gaseous and liquid products through contact cracking, the waste plastics can be recycled as a green resource, and the regenerated contact agent can be recycled for reuse; and the processing method can realize continuous processing of waste plastic raw materials, thereby improving processing efficiency; the method has strong adaptability to waste plastic raw materials and does not require crushing and cleaning; waste plastics in landfills can be dehydrated, dechlorinated and reduced in situ, and subsequent cracking recovery can be processed centrally, which facilitates expansion of production scale and reduces processing costs.

[0038] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings provide further understanding of the present disclosure and constitute a part of the specification. Together with the following detailed description, they are used to explain the present disclosure, but do not constitute a limitation of the present disclosure. Figure 1 The figure is a flow chart of the processing method of fluidized cracking of waste plastics.

[0040] In the attached figure:

[0041] 1-Plastic raw material storage tank 2-Second heating and conveying equipment 3-Cooling and crushing unit

[0042] 4-First heating and conveying equipment 5-Visbreaking reactor 6-Contact cracking reactor

[0043] 7-Contactant regenerator 8-Separation unit 9-Hydrogen chloride absorption unit 10~23-Pipeline DETAILED DESCRIPTION

[0044] The following describes the specific embodiments of the present disclosure in detail. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure.

[0045] In a first aspect, the present disclosure provides a method for processing waste plastics by fluidized cracking. Figure 1 The figure is a flow chart of the fluidized cracking process of waste plastics. Figure 1 As shown, the following steps are included:

[0046] S1, the plastic raw material enters the first heating and conveying equipment for liquefaction treatment to obtain liquefied plastic;

[0047] S2, the liquefied plastic and the dechlorination additive enter the visbreaking reactor to undergo visbreaking reaction and dechlorination to obtain liquefied plastic oil and the first dry gas;

[0048] S3, the liquefied plastic oil enters the contact cracking reactor, and contacts with the regenerated contact agent under dilute phase fluidized bed conditions to carry out cracking reaction, thereby obtaining reaction oil gas, regenerated contact agent and carbon ash;

[0049] S4, the charcoal ash and the regenerated contact agent enter the contact agent regenerator, react with oxygen to burn and regenerate, and obtain regenerated contact agent, regenerated flue gas and ash;

[0050] S5. Part or all of the ash is recycled to the visbreaking reactor as a dechlorination additive;

[0051] S6. The reaction oil and gas enter the separation unit for separation to obtain a second dry gas, liquefied gas, gasoline fraction, diesel fraction and wax oil fraction.

[0052] The regenerated contact agent is returned to the contact cracking reactor for continued use.

[0053] In a specific embodiment, the plastic raw material includes one or more of low-density polyethylene (LDPE), high-density polyethylene (HDPE), polystyrene (PS), polypropylene (PP), polyethylene terephthalate (PET) and polyvinyl chloride (PVC); the plastic raw material in the present disclosure can be directly made from waste plastics in landfills.

[0054] Optionally, the chlorine content in the plastic raw material is less than 10 weight %; the ash content is 1 weight % to 40 weight %, preferably 3 weight % to 20 weight %.

[0055] In a preferred embodiment, before step S1, the method further comprises the steps of hot melt dehydration, dechlorination, and crushing, such as Figure 1 As shown, the plastic raw material enters the second heating and conveying device 2, is melted and dehydrated under a first temperature condition to obtain a dehydrated plastic raw material, wherein the first temperature is 100°C to 170°C, and the residence time is 0.05h to 1h; the dehydrated plastic raw material is heated to a second temperature for dechlorination treatment to obtain a dehydrated and dechlorinated plastic raw material and hydrogen chloride-containing gas, wherein the second temperature is 150°C to 370°C, and the residence time is 0.05h to 0.5h; and the dehydrated and dechlorinated plastic raw material is directly fed into the first heating and conveying device 4 for liquefaction treatment.

[0056] In a specific embodiment, the dehydrated and dechlorinated plastic raw material is sequentially cooled and crushed in the cooling and crushing device 3 to obtain processed plastic raw material particles; and the processed plastic raw material particles are fed into the first heating and conveying device 4 for liquefaction treatment.

[0057] In a specific embodiment, the melting, dehydration and dechlorination steps and the plastic raw material liquefaction step are performed sequentially in the same heating and conveying equipment. For example, the second heating and conveying equipment and the first heating and conveying equipment use the same rapid heating and conveying equipment; for example, a screw conveying equipment with heating.

[0058] In a further embodiment, the method further comprises:

[0059] The hydrogen chloride-containing gas is passed into a hydrogen chloride absorption unit, where it comes into contact with a hydrogen chloride absorbent to absorb the hydrogen chloride. Optionally, the hydrogen chloride-containing gas is passed into the hydrogen chloride absorption unit under the action of a vacuum system. The hydrogen chloride absorbent is water or an alkaline solution commonly used in the art, and this disclosure is not limited thereto. For example, the alkaline solution includes one or more of sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution, sodium bicarbonate solution, sodium carbonate solution, and aqueous ammonia.

[0060] The present invention discloses a hot-melt dehydration, dechlorination and pulverization step and a hydrogen chloride absorption step for plastic raw materials, so that the chlorine in the waste plastic PVC in the plastic raw materials is decomposed into the gas phase, and a vacuum system is used to quickly separate the HCl, thereby avoiding the secondary reaction of the HCl, improving the dechlorination efficiency of the plastic raw materials, and reducing the corrosion pressure of subsequent equipment.

[0061] In a preferred embodiment, Figure 1 As shown, in step S4, the method also includes: allowing at least a portion of the first dry gas and / or at least a portion of the second dry gas to enter the contact agent regenerator, so that the regenerated contact agent and the charcoal-bearing ash undergo a complete combustion reaction in the presence of oxygen and dry gas to obtain regenerated flue gas, regenerated contact agent and ash; the present disclosure uses the dry gas generated in the waste plastic processing technology to regenerate the regenerated contact agent, and the dry gas combustion supplements heat energy, thereby improving resource utilization efficiency and contact agent regeneration efficiency.

[0062] Preferably, based on the total weight of the contact agent to be regenerated, the carbon content of the contact agent to be regenerated is 0.5 to 5.0% by weight.

[0063] In a specific embodiment, when the regeneration flue gas reaches the emission standard, the regeneration flue gas is discharged; wherein the regeneration flue gas emission standard is a conventional standard in this field, for example, refer to GB13271-2014 standard.

[0064] In one embodiment, in step S1, the first heating and conveying device is selected from a screw-type heating and conveying device; preferably, the screw-type heating and conveying device is selected from a twin-screw or single-screw conveying device with heating.

[0065] In a preferred embodiment, the process conditions of the liquefaction treatment include: the outlet temperature of the first heating and conveying equipment is 380°C to 500°C, preferably 400°C to 450°C; and the residence time is 5min to 30min, preferably 5min to 15min.

[0066] In one embodiment, in step S2, preferably, the visbreaking reactor is an adiabatic visbreaking reactor. In the present disclosure, the adiabatic visbreaking reactor can be any reactor known in the art, such as an upflow visbreaking reactor or a downflow visbreaking reactor.

[0067] In a preferred embodiment, the visbreaking treatment process conditions include: a reaction temperature of 380°C to 500°C, preferably 390°C to 450°C; and a residence time of 10 min to 90 min, preferably 20 min to 60 min. The preferred visbreaking process conditions in this embodiment can achieve a better viscosity reduction effect.

[0068] In one embodiment, in step S3, the process conditions of the cracking reaction include: a reaction temperature of 490°C to 750°C, a weight hourly space velocity of 1h -1 ~100h -1 The superficial gas velocity of the dilute phase fluidized bed is 0.3 to 8.0 m / s, and the mass ratio of the contact agent to the plastic raw material is 5 to 30: 1. In the present disclosure, the cracking reaction is carried out in a fluidized bed reactor, which is a conventional structure in the art.

[0069] In a preferred embodiment, in step S3, the cracking reaction process conditions include: a reaction temperature of 490°C to 750°C, a superficial gas velocity of 1.0 to 6.0 m / s in the fluidized bed, and a mass ratio of the contact agent to the waste plastic to be treated of 6 to 20:1. Carrying out the cracking reaction according to the process conditions of this embodiment can produce a more excellent cracking product distribution.

[0070] In a preferred embodiment, the method further comprises: the visbreaking liquefied plastic oil and steam enter the contact cracking reactor; preferably, the mass ratio of steam to plastic raw material is 0.05 to 1:1:1, preferably 0.1 to 0.5:1.

[0071] In one embodiment, in step S3, the contact agent is one or more selected from silicon-aluminum materials, quartz sand or coal char powder; the particle size of the contact agent can be 20 μm to 3000 μm, preferably 50 μm to 240 μm.

[0072] Optionally, the silicon-aluminum material is selected from a catalyst containing molecular sieves and / or a catalyst not containing molecular sieves; preferably, the catalyst containing molecular sieves is a catalyst containing one or more molecular sieves selected from X molecular sieve, Y molecular sieve, mordenite, ZSM-5, pillared clay molecular sieve, SAPO, or a spent FCC catalyst;

[0073] Preferably, the catalyst not containing molecular sieve is selected from a catalyst prepared using one or more of the first raw materials as raw materials, wherein the first raw materials include amorphous silica-alumina, clay, kaolin, montmorillonite, rectorite, illite, chlorite, pseudo-boehmite and silica; or

[0074] The catalyst not containing molecular sieves is selected from catalysts prepared using one or more of the second raw materials that have been acid-washed, calcined, and sieved as raw materials, wherein the second raw materials include amorphous silica-alumina, clay, kaolin, montmorillonite, rectorite, illite, and chlorite; or selected from catalysts prepared using one or more of the second raw materials that have been acid-washed, calcined, and sieved and pseudo-boehmite and / or silica as raw materials;

[0075] Optionally, the coal coke powder is coal powder and / or petroleum coke powder.

[0076] In one embodiment, the contact agent regenerator is a dense fluidized bed regenerator; preferably, the regeneration process conditions include: an air residence time of 0.5 to 60 seconds, preferably 1.0 to 10 seconds, a reaction temperature of 600°C to 750°C, preferably 600°C to 700°C, a gas containing 10% to 50% oxygen by volume, and a dense bed superficial gas velocity of 0.05 to 0.6 m / s, preferably 0.2 to 0.4 m / s. The dense fluidized bed regenerator in this disclosure uses a device conventionally selected in the art.

[0077] In one embodiment, the ash is partially recycled to the visbreaking reactor as a dechlorination additive, and the remaining ash is discharged from the device. The weight ratio of the recycled ash to the liquefied waste plastic is (0.025-0.045):1, preferably (0.03-0.04):1.

[0078] In one embodiment, the plastic raw material is first subjected to dehydration and dechlorination pretreatment and then to liquefaction treatment. The dehydration and dechlorination pretreatment part includes a second heating and conveying device and a vacuum device connected to the second heating and conveying device; preferably, the second heating and conveying device is selected from a twin-screw or single-screw conveying device with heating.

[0079] In a preferred embodiment, the process conditions of the dehydration and dechlorination pretreatment include: a first temperature of 100°C to 170°C, preferably 120°C to 150°C; a residence time of 0.05h to 1h, preferably 0.05h to 0.5h; a second temperature of 150°C to 370°C, preferably 220°C to 350°C; a residence time of 0.05h to 0.5h, preferably 0.1h to 0.2h; a vacuum degree of 50mmHg to 300mmHg, preferably 50mmHg to 150mmHg; preferably, a heating rate from the first temperature to the second temperature of 50°C / min to 200°C / min, preferably 50°C / min to 150°C / min. In the present disclosure, a gradual heating method is adopted, first heating to the first temperature for melt dehydration treatment, and then heating to the second temperature for dechlorination treatment, thereby improving the dehydration and dechlorination effect of waste plastics. The feeding rate of the plastic raw material is related to the processing capacity of the second heating and conveying device. In one embodiment, the feeding rate of the plastic raw material is 5 kg / h to 5000 kg / h, preferably 100 kg / h to 4000 kg / h.

[0080] In one embodiment, the dehydrated and dechlorinated plastic raw material is further cooled and pulverized to obtain treated plastic raw material particles, wherein the particle size of the dehydrated and dechlorinated plastic raw material particles is 100 μm to 2000 μm. The preparation of the dehydrated and dechlorinated plastic raw material particles facilitates the storage and transportation of the plastic raw material.

[0081] In the present disclosure, the apparatus and method for the cooling treatment and the pulverizing treatment may be conventional apparatus and method in the art.

[0082] The beneficial effect of the fluidized cracking process for viscous dechlorination of waste plastics provided by the present invention is that it overcomes technical problems currently existing in the field of pyrolysis treatment of waste plastics. During their research, the inventors discovered that one of the technical problems with the existing technology is that polyvinyl chloride in waste plastics decomposes upon heating to produce HCl, which rapidly reacts with double bonds in the raw materials to form chlorinated hydrocarbons, making it difficult to efficiently remove chlorine from the waste plastics using conventional reaction apparatus. To address the first technical problem, the present invention uses specialized equipment to rapidly heat the polyvinyl chloride-containing waste plastics to decompose it, and uses a vacuum method to quickly separate the decomposed HCl from the reactor, thereby improving dechlorination efficiency. The second technical problem in the existing technology overcomes: Plastic raw materials are high molecular weight polymers. Due to their huge molecular weight and solid state, the heat transfer inside the plastic is very slow. Traditional heating methods will cause the plastic's exterior to be overheated and cracked, while the interior of the plastic remains solid. As a result, the plastic pyrolysis coke rate is high and the gas yield is high. To address the second difficulty, special equipment is used to increase the heating area through strong extrusion and stirring to quickly heat the waste plastic until it becomes a flowable liquid, and the viscosity is reduced so that it can be transported using a pump. When the plastic raw material is quickly liquefied, the thermal conductivity of the liquid is greatly increased. A heating furnace or other heating equipment can be used to perform a pyrolysis reaction on the liquefied plastic oil, which can obtain a higher liquid yield and a lower coking rate. The third technical problem overcomes: The density of the plastic raw material is low, and the rate at which the plastic raw material enters the reaction device is low. The processing scale of the existing technology is small and cannot meet the needs of modern large-scale recycling. To address the third technical problem, after the plastic raw material is liquefied, the method provided by the present invention greatly increases the transportation density of the raw material. Therefore, it can not only achieve large-scale processing of waste plastics but also achieve continuous pyrolysis recovery of plastic raw materials.

[0083] In a second aspect, the present disclosure provides a processing system for fluidized cracking of waste plastics, comprising a first heating and conveying device, a visbreaking reactor, a contact cracking reactor, a separation unit, and a contact agent regenerator connected in sequence;

[0084] The first heating and conveying device includes a raw material inlet and a liquefied plastic outlet, and the first heating and conveying device is configured to liquefy the plastic raw material;

[0085] The visbreaking reactor comprises a liquefied plastic inlet, a dechlorination additive inlet, a liquefied plastic oil outlet and a first dry gas outlet, and the visbreaking reactor is configured to perform visbreaking treatment on the liquefied plastic;

[0086] The contact cracking reactor includes a cracking feed inlet, a contact agent inlet, a reaction oil and gas outlet, and a regenerated contact agent outlet; the cracking feed inlet is connected to the liquefied plastic oil outlet of the visbreaking reactor, and the contact cracking reactor is configured to perform a cracking reaction on the liquefied plastic oil;

[0087] The separation unit includes a reaction oil and gas inlet, a second dry gas outlet, a liquefied gas outlet, a gasoline fraction outlet, a diesel fraction outlet, and a wax oil fraction outlet; the separation unit is configured to separate the reaction oil and gas;

[0088] The contact agent regenerator includes an inlet for regenerated contact agent, an inlet for oxygen-containing gas, an outlet for regenerated contact agent, an ash outlet and a regenerated flue gas outlet; the contact agent regenerator is configured to react the regenerated contact agent with oxygen to perform char regeneration to obtain regenerated contact agent and regenerated flue gas; the regenerated contact agent outlet is connected to the contact agent inlet of the contact cracking reactor; the ash outlet is connected to the dechlorination additive inlet of the visbreaking reactor.

[0089] In a specific embodiment, the connecting pipeline between the cracking feed inlet of the contact cracking reactor and the liquefied plastic oil outlet of the visbreaking reactor further includes a steam inlet, which helps to atomize the liquefied waste plastic oil.

[0090] In a preferred embodiment, the contact agent regenerator further comprises a dry gas inlet, which is connected to the first dry gas outlet of the visbreaking reactor and / or the second dry gas outlet of the separation unit.

[0091] In a specific embodiment, before the first heating and conveying device, the processing system further includes a second heating and conveying device, a hydrogen chloride absorption unit and a cooling and crushing unit connected in sequence;

[0092] The second heating and conveying equipment includes a raw material inlet, a dehydrated and dechlorinated plastic outlet, and a hydrogen chloride-containing gas outlet; the waste plastic hot melt dehydration and dechlorination unit is configured to perform melting, dehydration, and dechlorination treatments on the chlorine-containing waste plastic;

[0093] The hydrogen chloride absorption unit includes a gas inlet and a hydrogen chloride absorbent; the gas inlet is connected to the hydrogen chloride-containing gas outlet of the second heating and conveying equipment;

[0094] The cooling and pulverizing unit is configured to perform cooling and pulverizing processing on the dehydrated and dechlorinated plastic from the second heating and conveying device.

[0095] In a specific embodiment, the first heating and conveying equipment is a screw-type heating and conveying equipment; the second heating and liquefying conveying equipment is a screw-type heating and conveying equipment and a vacuum device connected to the screw-type heating and conveying equipment; preferably, the screw-type heating and conveying equipment is selected from a single-screw or twin-screw heating and conveying equipment with heating.

[0096] In a preferred embodiment, the second heating and conveying device and the first heating and conveying device are a single heating and conveying device, including a first screw-type heating and conveying device, wherein a hydrogen chloride gas outlet connected to a vacuum device is provided in the middle of the screw-type heating and conveying device.

[0097] In a specific embodiment, the second heating and conveying equipment further includes a non-condensing steam outlet for leading out the non-condensing steam.

[0098] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention and the accompanying drawings, but the accompanying drawings and embodiments do not constitute a limitation of the present invention.

[0099] like Figure 1As shown, the plastic raw materials stored in the plastic raw material storage tank 1 enter the second heating and conveying equipment 2 for hot melting dehydration and dechlorination to obtain dehydrated and dechlorinated plastic raw materials and hydrogen chloride-containing gas. The hydrogen chloride-containing gas is pumped into the hydrogen chloride absorption unit 9 through a vacuum system to contact with a hydrogen chloride absorbent for hydrogen chloride absorption treatment, and a small amount of non-condensable gas is discharged through the pipeline 23; the dehydrated and dechlorinated waste plastics are cooled and pulverized in the cooling and pulverization unit 3 in sequence to obtain pretreated plastic raw material particles, which can be stored and transported. Alternatively, the plastic raw material particles are fed into the first heating and conveying device 4 for liquefaction treatment to obtain liquefied plastic; the liquefied plastic enters the plastic viscosity reducing reactor 5 for viscosity reducing and cracking treatment to obtain liquefied plastic oil and the first dry gas; the liquefied plastic oil after viscosity reducing is fed to the contact cracking reactor 6 via the pipeline 11 and the steam from the pipeline 10, the fresh contact agent replenished from the pipeline 13 and the regenerated contact agent from the pipeline 18 of the regenerator enter the contact cracking reactor 6, the liquefied plastic oil contacts the fluidized contact agent in the contact cracking reactor 6 to undergo cracking reaction, and reaction oil gas and regenerated contact agent are obtained; after gas-solid separation, the reaction oil gas enters the subsequent separation unit 8 via the pipeline 12 for separation treatment, wherein: The second dry gas leaves the device through pipeline 22, and the liquefied gas, gasoline fraction, diesel fraction and wax oil fraction leave the device through pipeline 16; the regenerated contact agent with char and optional ash with char enter the contact agent regenerator 7 through pipeline 14, the coke on the regenerated contact agent and the cracking dry gas from pipeline 21 (including the first dry gas from pipeline 22 and / or the second dry gas from pipeline 15) and the air from pipeline 19 react and burn completely, and the generated regenerated flue gas leaves the device through pipeline 17 and can be directly discharged into the atmosphere after meeting the standards. The obtained regenerated contact agent is led out of the contact agent regenerator 7 through pipeline 18, and part of the ash is circulated to the viscosity reducing reactor from pipeline 20 for use as a dechlorination additive. The balance agent and part of the ash are discharged from the device.

[0100] The present disclosure is further described in detail below through examples. The raw materials used in the examples can be obtained through commercial channels.

[0101] The contact agent SL-1 used is a contact agent prepared by spray drying and calcining a slurry containing 10 wt% alumina and 80 wt% kaolin. The specific preparation method is referred to document CN102974383A; the average particle size of SL-1 is 80 μm.

[0102] The second contact agent used was a catalytic cracking balance agent with a trade name of CRC-1 (produced by Qilu Petrochemical Company) and an average particle size of 65 μm.

[0103] The third contact agent used was quartz sand with a particle size of 240 μm.

[0104] In the following examples, the particle size of the contact agent was measured by a particle size detector.

[0105] The analytical method for chlorine content in liquefied waste plastics is: Q / SH 3360270-2018.

[0106] The analytical method for viscosity of liquefied waste plastics is: SH / T 0739-2003.

[0107] The analysis methods for other elements in liquefied waste plastics are: carbon and hydrogen elements SH / T 0656-2017, oxygen element SH / T0986, nitrogen element SH / T 0704-2010, and sulfur element SH / T 0842-2010.

[0108] The cracking product distribution was obtained by the simulated distillation NB / SH / T 0829-2010 method.

[0109] The density analysis method of diesel wax oil is SH / T0604-2000; the cracking gas composition is determined by the RIPP 78-90 method; the hydrocarbon composition of naphtha, diesel, etc. is determined by chromatography analysis.

[0110] In the following examples, the particle size of the particles obtained by the pulverization process ranges from 5 to 8 mm.

[0111] Example 1

[0112] The plastic raw material is waste agricultural film, and the composition is shown in Table 1.

[0113] Liquefaction treatment steps: The plastic raw material is fed into a twin-screw heating and conveying equipment for liquefaction treatment at a feed rate of 100 kg / h, an outlet temperature of the twin-screw heating and conveying equipment of 390°C, and a residence time of 12 min to obtain liquefied plastic LP-1, the composition of which is shown in Table 1.

[0114] Visbreaking step: Using an adiabatic visbreaking reactor, the liquefied plastic was introduced via a screw pump into the reactor for visbreaking. The visbreaking reaction temperature was 390°C and the visbreaking reaction time was 60 minutes to obtain a visbroken liquefied plastic oil. Chlorine content was analyzed and viscosity was tested.

[0115] The contact cracking reactor adopts a riser reactor, and the contact agent is quartz sand. The liquefied plastic oil and steam enter the riser reactor from the bottom, and the quartz sand enters the riser reactor from the bottom, and flows upward under the lifting of the lifting gas. The liquefied plastic oil and the contact agent flow upward and undergo a cracking reaction. The gas and solid separation is carried out at the top of the reactor to obtain reaction oil gas and to-be-generated contact agent. The reaction oil and gas are further separated, wherein the mass ratio of the contact agent to the plastic raw material is 7:1. The cracking reaction process conditions are: reaction temperature is 510°C, apparent gas velocity is 6.0m / s, and the mass ratio of steam to plastic raw material is 0.4:1.

[0116] Contact agent regeneration process: The contact agent regenerator is a dense phase fluidized bed reactor. Regenerated contact agent (carbon content: 1.3 wt%) and air are introduced into the contact agent regenerator for char regeneration. The regeneration temperature is 660°C, the superficial gas velocity in the dense phase bed is 0.3 m / s, and the contact agent residence time is 3 seconds. The regenerated contact agent is returned to the contact cracking reactor for recycling. The first dry gas from the visbreaking reactor and the second dry gas from the separation unit are introduced into the contact agent regenerator to react with oxygen to adjust the regeneration temperature.

[0117] The ash from the regeneration unit was recycled to the visbreaking reactor as a dechlorination additive, with a weight ratio of recycled ash to plastic feedstock of 0.035:1. The liquefied plastic oil was analyzed again for chlorine content under the same visbreaking reaction conditions (reaction temperature 390°C, reaction time 60 minutes). The product distribution of the cracking reaction products is shown in Table 4. The ash composition and chlorine content of the visbreaking products are shown in Tables 5 and 6.

[0118] Example 2

[0119] The plastic raw materials are the same as those in Example 1.

[0120] The plastic raw materials are dehydrated, dechlorinated and liquefied using the same twin-screw heating and conveying equipment with segmented temperature control.

[0121] Dehydration and dechlorination steps: the plastic raw material is added to a twin-screw heating and conveying device at a feeding rate of about 5 kg / h, and is melted and dehydrated under the conditions of a first temperature of 150° C. and a residence time of 0.1 h; dechlorination is carried out under the conditions of a second temperature of 300° C. and a residence time of 0.1 h, and the heating rate from the first temperature to the second temperature is 100° C. / min; the twin-screw heating and conveying device is connected to a vacuum pumping device with a vacuum degree of 150 mmHg to obtain a dehydrated and dechlorinated plastic raw material.

[0122] Liquefaction treatment step: The dehydrated and dechlorinated plastic raw material was liquefied using the same twin-screw heating and conveying equipment. The outlet temperature of the twin-screw heating and conveying equipment is listed in Table 2. The residence time is 12 minutes to obtain liquefied plastics LP-2a, LP-2b, LP-2c, and LP-2d. The composition and content of the liquefied plastic LP-2b are shown in Table 1.

[0123] Visbreaking step: The liquefied plastics obtained by liquefaction treatment at different temperatures were subjected to visbreaking treatment to obtain liquefied plastic oils 1-8 with different treatment conditions. The chlorine content was analyzed and the viscosity of the liquefied plastic oils was tested. The reaction conditions and results are shown in Table 2.

[0124] Liquefied plastic oil 4 (LP-2b-60, viscosity reduction reaction temperature 390°C, reaction time 60 minutes) was used as the cracking feedstock. The contact cracking reactor employed a riser reactor. The contact agent SL-1 was introduced from the bottom of the riser reactor by lifting gas. The liquefied plastic oil and steam then flowed upward with the fluidized contact agent, undergoing a cracking reaction. This reaction oil gas and regenerated contact agent then entered a gas-solid separation device at the top of the riser reactor for gas-solid separation. The separated reaction oil gas was further separated, and the separated regenerated contact agent and carbon-bearing ash were then introduced into a contact agent regenerator for char regeneration.

[0125] The mass ratio of the contact agent to the plastic raw material is 7:1, and the process conditions of the cracking reaction include: a reaction temperature of 510°C, a superficial gas velocity of 6.0 m / s, and a mass ratio of steam to the plastic raw material of 0.4:1;

[0126] The regeneration steps for the regenerated contact agent and charcoal-bearing ash were the same as in Example 1. The ash obtained from the regeneration unit was recycled to the visbreaking reactor as a dechlorination additive, with a weight ratio of recycled ash to plastic feedstock of 0.035:1. Liquefied plastic oil 4 was again analyzed for chlorine content under the same visbreaking reaction conditions (reaction temperature 390°C, reaction time 60 minutes). The product distribution of the cracking reaction products is shown in Table 4. The ash composition and chlorine content of the visbreaking products are shown in Tables 5 and 6.

[0127] Table 1 Composition and content of plastic raw materials and liquefied plastics

[0128] Plastic raw materials waste agricultural film Example 1 Example 2 Preprocessing steps / / After melting, dehydration and dechlorination treatment Liquefaction process steps / Feed rate, kg / h / 100 5 Outlet temperature, °C / 390 390 Residence time, min / 12 12 Composition content: W (ash content) / % 3.05 3.05 3.05 W(O) / % 2.60 2.60 2.60 W(C) / % 81.21 81.24 81.32 W(H) / % 12.87 12.87 12.89 W(S) / % <0.1 <0.1 <0.1 W(N) / % 0.030 0.030 0.030 W(Cl) / % 0.15 0.12 0.018 W (metal analysis) / (μg / g) Ca 1.54 1.16 0.709 Fe - - - Si 1.131 0.925 0.851

[0129] Table 2 Viscosity properties of liquefied plastic oil obtained under liquefaction treatment and viscosity reduction reaction conditions in Example 2 In the table, the “-” in the viscosity column indicates that the viscosity is too high to be tested.

[0130] Example 3

[0131] The liquefied plastic oil 6 (LP-2c-60, viscosity reduction reaction temperature 396° C., reaction time 60 min) after viscosity reduction treatment in Example 2 was used as the cracking raw material.

[0132] The same process as Example 2 was used, using SL-1 as the contact agent. The difference was that the ash from the contact agent regenerator was recycled to the visbreaking reactor as a dechlorination additive, with a weight ratio of recycled ash to plastic feedstock of 0.04:1. The product distribution of the cracking reaction products is shown in Table 4. The chlorine content of the visbreaking products before and after ash recycling is shown in Table 5.

[0133] Example 4

[0134] Plastic raw material 2 is household waste plastic, and its properties are shown in Table 1.

[0135] A twin-screw heating and conveying device is used as the melt dehydration and dechlorination device. The plastic raw material feeding rate is about 5 kg / h. The process conditions of the melt dehydration and dechlorination treatment are as follows: the first temperature is 150°C; the residence time is 0.1h; the second temperature is 300°C; the residence time is 0.1h, and the heating rate from the first temperature to the second temperature is 100°C / min; the vacuum degree of the screw heating and conveying device is 150 mmHg, and a dehydrated and dechlorinated plastic raw material is obtained.

[0136] The dehydrated and dechlorinated plastic raw material was liquefied using the same twin-screw heating and conveying equipment to obtain liquefied plastic LP-3. The properties are shown in Table 1. The process conditions for the liquefaction treatment were: an outlet temperature of 390°C for the twin-screw heating and conveying equipment, and a residence time of 12 min. The obtained liquefied waste plastic was subjected to visbreaking treatment. The process conditions for the visbreaking treatment included a reaction temperature of 390°C and a reaction time of 60 min to obtain liquefied plastic oil LP-3-60.

[0137] Using liquefied plastic oil LP-3-60 as the raw material, the cracking reaction steps were the same as in Example 2, using contact agent SL-1. The product distribution of the cracking reaction products is shown in Table 4. The chlorine content of the visbreaking products before and after ash recycling is shown in Table 5.

[0138] Table 3 Composition and content of plastic raw materials and liquefied plastics

[0139] Plastic raw materials household waste plastics Example 4 Preprocessing steps / Melting dehydration and dechlorination treatment Liquefaction process steps / Feed rate, kg / h / 5 Outlet temperature, °C / 390 Residence time, min / 12 Composition content: W (ash content) / % 13.54 13.73 W(O) / % 9.54 9.67 W(C) / % 64.87 66.77 W(H) / % 8.60 8.72 W(S) / % 0.089 0.090 W(N) / % 0.18 0.18 W(Cl) / % 2.185 0.834 W (metal analysis) / (μg / g) Ca 8.657 6.326 Fe 1.125 0.894 Si 1.654 0.852

[0140] Example 5

[0141] The liquefied plastic oil LP-3-60 obtained in Example 4 was used as the raw material, and the same process as in Example 5 was employed, except that the contact agent CRC-1 was used, and the visbroken liquefied plastic oil and steam were introduced into a contact cracking reactor (riser reactor), where they contacted the fluidized contact agent to undergo a cracking reaction, yielding reaction oil gas and regenerated contact agent. The mass ratio of the contact agent to the plastic raw material was 7:1, and the process conditions for the cracking reaction included a reaction temperature of 500°C, a superficial gas velocity of 4.0 m / s, and a mass ratio of steam to the plastic raw material of 0.4:1. The product distribution of the cracking reaction products is shown in Table 4. The chlorine content of the visbroken products before and after ash recycling is shown in Table 5.

[0142] Table 4 Distribution of cracking products

[0143]

[0144] According to the data in Table 4, when the process flow and conditions of the present disclosure are met, the yield of the C5-180°C fraction is 53.33% to 63.20% by weight.

[0145] Table 5 Ash composition

[0146]

[0147]

[0148] Table 6 Chlorine content of viscosity-reduced products

[0149] Example 1 Example 2 Example 3 Example 4 Example 5 Plastic raw materials Waste agricultural film Waste agricultural film Waste agricultural film Household plastic waste Household plastic waste Dehydration and dechlorination treatment none have have have have Visbreaking products LP-1-60 LP-2-60 LP-2-60 LP-3-60 LP-3-60 Ash-free circulating chlorine content, ppm 120.00 58.00 55.00 333.60 390.00 Ash circulating chlorine content, ppm 66.00 23.00 18.00 123.50 132.00 Ash to raw material weight ratio 0.035 0.035 0.04 0.035 0.035

[0150] As can be seen from Table 6, when the ash is recycled to the visbreaking reactor as a dechlorination additive, the chlorine content in the visbreaking product can be greatly reduced, which can effectively prevent chlorine corrosion and reduce the chlorine content in the product.

Claims

1. A fluidized cracking method for processing waste plastics, characterized in that: The following steps are involved: S1, the plastic raw material enters the first heating and conveying equipment for liquefaction treatment to obtain liquefied plastic; S2, the liquefied plastic and the dechlorination additive enter the visbreaking reactor to undergo visbreaking reaction and dechlorination to obtain liquefied plastic oil and the first dry gas; S3, the liquefied plastic oil enters the contact cracking reactor, and contacts with the high-temperature contact agent under the condition of a dilute phase fluidized bed to carry out a cracking reaction, thereby obtaining reaction oil gas, the spent contact agent and the carbon ash; S4, the regenerated contact agent and the ash with carbon enter the contact agent regenerator, react with oxygen and burn to regenerate, and obtain regenerated contact agent, regenerated flue gas and ash; S5. Part or all of the ash is recycled to the visbreaking reactor as a dechlorination additive; S6. The reaction oil and gas enter the separation unit for separation to obtain a second dry gas, liquefied gas, gasoline fraction, diesel fraction and wax oil fraction.

2. The fluidized cracking method for waste plastics according to claim 1, characterized in that: Before step S1, the method further includes: The plastic raw material enters the second heating and conveying device, is melted and dehydrated at a first temperature to obtain a dehydrated plastic raw material, and then is heated to a second temperature for dechlorination treatment to obtain a dehydrated and dechlorinated plastic raw material and hydrogen chloride-containing gas, and the dehydrated and dechlorinated plastic raw material is directly fed into the first heating and conveying device for liquefaction treatment; Preferably, the dehydrated and dechlorinated plastic raw material is sequentially cooled and crushed in a cooling and crushing unit to obtain dehydrated and dechlorinated plastic raw material particles; the dehydrated and dechlorinated plastic raw material particles are fed into a first heating and conveying device; Optionally, the particle size of the plastic raw material particles is 0.5 mm to 10 mm.

3. The fluidized cracking method for waste plastics according to claim 2, characterized in that: The method further includes: The hydrogen chloride-containing gas contacts a hydrogen chloride absorbent to remove hydrogen chloride; The hydrogen chloride absorbent is water or an alkaline solution with a pH value greater than 7; optionally, the alkaline solution is selected from one or more of sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution, sodium bicarbonate solution, sodium carbonate solution and ammonia water.

4. The fluidized cracking method for waste plastics according to claim 1, characterized in that: In step S4, the method further includes: introducing at least a portion of the first dry gas and / or at least a portion of the second dry gas into a contact agent regenerator, causing the regenerated contact agent and the charcoal-bearing ash to completely burn in the presence of oxygen and dry gas to obtain regenerated contact agent, regenerated flue gas and ash; Preferably, based on the total weight of the contact agent, the carbon content of the contact agent to be produced is 0.5 to 5.0% by weight.

5. The fluidized cracking method for processing waste plastics according to any one of claims 1 to 4, characterized in that: In step S1, the first heating and conveying device is selected from a screw-type heating and conveying device; preferably, the first heating and conveying device is selected from a twin-screw or single-screw heating and conveying device with heating; Preferably, the process conditions of the liquefaction treatment include: an outlet temperature of 380°C to 500°C, preferably 400°C to 450°C; and a residence time of 5 min to 30 min, preferably 5 min to 15 min.

6. The fluidized cracking method for processing waste plastics according to any one of claims 1 to 4, characterized in that: In step S2, the visbreaking reactor is an adiabatic visbreaking reactor; Preferably, the process conditions of the visbreaking reaction include: a reaction temperature of 360° C. to 490° C., preferably 370° C. to 420° C.; and a residence time of 10 min to 90 min, preferably 20 min to 60 min.

7. The fluidized cracking method for processing waste plastics according to any one of claims 1 to 4, characterized in that: In step S3, the process conditions of the cracking reaction include: a reaction temperature of 490° C. to 750° C., a superficial gas velocity of the dilute phase fluidized bed of 0.3 to 8.0 m / s, and a mass ratio of the contact agent to the plastic raw material of 5 to 30:1; Preferably, the reaction temperature is 500°C to 650°C, the superficial gas velocity of the dilute phase fluidized bed is 1.0 to 6.0 m / s, and the mass ratio of the contact agent to the plastic raw material is 6 to 20:1; Preferably, steam is allowed to enter the contact cracking reactor; the mass ratio of steam to plastic raw material is 0.05 to 1:1, more preferably 0.1 to 0.5:

1.

8. The fluidized cracking method for processing waste plastics according to any one of claims 1 to 4, characterized in that: In step S3, the contact agent is selected from one or more of silicon-aluminum materials, quartz sand or coal coke powder; preferably, the particle size of the contact agent is 50 μm to 240 μm; Optionally, the silicon-aluminum material contains molecular sieve or does not contain molecular sieve; wherein, the molecular sieve is one or more selected from X molecular sieve, Y molecular sieve, mordenite, ZSM-5, pillared clay molecular sieve and SAPO; optionally, the coal char powder is coal powder and / or petroleum coke powder.

9. The fluidized cracking method for processing waste plastics according to any one of claims 1 to 4, characterized in that: In step S4, the contact agent regenerator is a dense phase fluidized bed reactor, and the process conditions include: a residence time of 0.5 seconds to 60 seconds, preferably 1.0 seconds to 10 seconds, a regeneration temperature of 600°C to 750°C, preferably 600°C to 700°C, air or a mixture of air and inert gas is introduced, and the superficial gas velocity of the dense phase bed is 0.05m / s to 0.6m / s, preferably 0.2m / s to 0.4m / s.

10. The fluidized cracking method for waste plastics according to any one of claims 1 to 4, characterized in that: In step S2, the weight ratio of the dechlorination additive to the liquefied plastic is (0.025-0.045):1, preferably (0.03-0.04):

1.

11. The fluidized cracking method for waste plastics according to claim 2, characterized in that: The second heating and conveying device includes a screw-type heating and conveying device and a vacuum device connected to the screw-type heating and conveying device; preferably, the screw-type heating and conveying device is selected from a twin-screw or single-screw conveying device with heating; Preferably, the process conditions of the second heating conveying equipment include: a first temperature of 100° C. to 170° C., preferably 120° C. to 150° C.; a residence time of 0.05 h to 1 h, preferably 0.05 h to 0.5 h; a second temperature of 150° C. to 370° C., preferably 220° C. to 350° C.; a residence time of 0.05 h to 0.5 h, preferably 0.1 h to 0.2 h; a vacuum degree of 50 mmHg to 300 mmHg, preferably 50 mmHg to 150 mmHg; Preferably, the heating rate from the first temperature to the second temperature is 50° C. / min to 200° C. / min, preferably 50° C. / min to 150° C. / min.

12. The fluidized cracking method for waste plastics according to claim 1, characterized in that: The plastic raw material is selected from one or more of LDPE, HDPE, PS, PP, PET and PVC; Optionally, the chlorine content in the plastic raw material is less than 10 weight %; the ash content is 1 weight % to 40 weight %, preferably 3 weight % to 20 weight %.

13. A processing system for fluidized cracking of waste plastics, characterized in that: It comprises a first heating and conveying device, a visbreaking reactor, a contact cracking reactor, a separation unit and a contact agent regenerator which are connected in sequence; The first heating and conveying device includes a raw material inlet and a liquefied plastic outlet, and the first heating and conveying device is configured to liquefy the plastic raw material; The visbreaking reactor comprises a liquefied plastic inlet, a dechlorination additive inlet, a liquefied plastic oil outlet and a first dry gas outlet, and the visbreaking reactor is configured to perform visbreaking treatment on the liquefied plastic; The contact cracking reactor includes a cracking feed inlet, a contact agent inlet, a reaction oil and gas outlet, and a regenerated contact agent outlet; the cracking feed inlet is connected to the liquefied plastic oil outlet of the visbreaking reactor, and the contact cracking reactor is configured to perform a cracking reaction on the liquefied plastic oil; The separation unit includes a reaction oil and gas inlet, a second dry gas outlet, a liquefied gas outlet, a gasoline fraction outlet, a diesel fraction outlet, and a wax oil fraction outlet; the separation unit is configured to separate the reaction oil and gas; The contact agent regenerator includes an inlet for regenerated contact agent, an inlet for oxygen-containing gas, an outlet for regenerated contact agent, an ash outlet and a regenerated flue gas outlet; the contact agent regenerator is configured to react the regenerated contact agent with oxygen to perform char regeneration to obtain regenerated contact agent and regenerated flue gas; the regenerated contact agent outlet is connected to the contact agent inlet of the contact cracking reactor; the ash outlet is connected to the dechlorination additive inlet of the visbreaking reactor.

14. The processing system for fluidized cracking of waste plastics according to claim 13, characterized in that: Before the first heating and conveying device, it also includes a second heating and conveying device, a hydrogen chloride absorption unit and a cooling and crushing unit that are connected in sequence; The second heating and conveying equipment includes a raw material inlet, a dehydrated and dechlorinated plastic outlet, and a hydrogen chloride-containing gas outlet; the waste plastic hot melt dehydration and dechlorination unit is configured to perform melting, dehydration, and dechlorination treatments on the chlorine-containing waste plastic; The hydrogen chloride absorption unit includes a gas inlet and a hydrogen chloride absorbent; the gas inlet is connected to the hydrogen chloride-containing gas outlet of the second heating and conveying equipment; The cooling and pulverizing unit is configured to cool and pulverize the dehydrated and dechlorinated plastic from the second heating and conveying device; Preferably, the contact agent regenerator further comprises a dry gas inlet, wherein the dry gas inlet is connected to the first dry gas outlet of the visbreaking reactor and / or the second dry gas outlet of the separation unit; Optionally, the connecting pipeline between the cracking feedstock inlet of the contact cracking reactor and the liquefied plastic oil outlet of the visbreaking reactor further includes a steam inlet; Preferably, the first heating and conveying device is a screw-type heating and conveying device; Preferably, the waste second heating liquefaction conveying equipment is a screw heating conveying equipment and a vacuum device connected to the screw heating conveying equipment; preferably, the screw heating conveying equipment is selected from a single-screw or twin-screw heating conveying equipment with heating.

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