A processing method and processing system for fluidized cracking of waste plastics

Abstract

The present application relates to a kind of waste plastic fluidized cracking processing method and processing system, the method comprises the following steps: S1, plastic raw material enters first heating conveying equipment and is treated, obtains liquefied plastic;S2, liquefied plastic and dechlorination additive enter viscosity breaking reactor and carry out viscosity breaking reaction and dechlorination, obtain liquefied plastic oil and first dry gas;S3, liquefied plastic oil enters contact cracking reactor, under the condition of dilute phase fluidized bed, with regenerated contactant contact and carry out cracking reaction, obtain reaction oil gas, spent contactant and carbon-containing ash;S4, carbon-containing ash and spent contactant enter contactant regenerator, and with oxygen reaction and coke regeneration, obtain regenerated contactant, regenerated flue gas and ash;S5, the ash of described as dechlorination additive is recycled;S6, the reaction oil gas of described enters separation unit and is separated to obtain second dry gas, liquefied gas, gasoline fraction, diesel fraction and wax oil fraction.The present application realizes waste plastic resource utilization.

Description

Technical Field

[0001] This disclosure relates to the field of waste plastic resource recycling, specifically to a processing method and system for fluidized bed cracking of waste plastics. Background Technology

[0002] With technological advancements and industrial development, plastics are now widely used as packaging materials in daily life. Used waste plastics cannot decompose naturally. While only a few types can be recycled through specific channels, a large amount ends up in landfills as household waste, occupying significant space due to their slow decomposition. Especially in recent years, the generation of waste plastics has increased dramatically, making rapid and environmentally friendly recycling an urgent task.

[0003] The simplest way to dispose of waste plastics is through direct incineration, but this produces toxic gases harmful to human health and causes secondary environmental pollution. Waste plastic pyrolysis technology involves breaking down waste plastics under anaerobic or oxygen-deficient conditions through heating or the presence of a catalyst. This process breaks down polymers into lower molecular weight substances, yielding gasoline, kerosene, diesel fractions, and some pyrolysis gases. Waste plastic pyrolysis technology alleviates the pollution caused by waste plastics and enables their recycling, representing an important direction for the resource-based treatment of waste plastics.

[0004] Currently, waste plastic pyrolysis and recycling technologies mainly include waste plastic pyrolysis and catalytic pyrolysis. CN201710726352.9 discloses a method and equipment for producing gasoline and diesel from waste plastic pyrolysis. This system dissolves crushed and impurity-removed waste plastic in liquid pyrolysis oil, and through precise temperature control, performs melting, dehydration, dechlorination, and pyrolysis upgrading. The process requires a large amount of solvent oil. CN200780003589.9 discloses a method and apparatus for contact decomposition of waste plastic, belonging to catalytic pyrolysis technology. It uses a heated and stirred rotary kiln as a reactor, with an FCC catalyst as the heat medium and catalytic center, and adds appropriate amounts of Ca and Fe compounds to decompose the waste plastic. However, this device requires the contact agent in the reactor to be removed and regenerated after a period of operation. Many other waste plastic pyrolysis technologies use batch pyrolysis reactors. These methods suffer from small processing scales and fail to remove impurities from the products. Summary of the Invention

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

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

[0007] S1. Plastic raw materials enter the first heating and liquefaction conveying equipment for liquefaction treatment to obtain liquefied plastic;

[0008] S2. The liquefied plastic and dechlorination additive enter the viscosity-reducing cracking reactor for viscosity-reducing cracking reaction and dechlorination to obtain liquefied plastic oil and first dry gas;

[0009] S3. The liquefied plastic oil enters the contact cracking reactor and, under dilute phase fluidized bed conditions, comes into contact with a high-temperature contact agent to carry out a cracking reaction, yielding reaction oil gas, unused contact agent, and carbonized ash.

[0010] S4. The recycled contact agent and carbonized ash enter the contact agent regenerator, where they react with oxygen to burn off the coke and regenerate, yielding regenerated contact agent, regenerated flue gas, and ash.

[0011] S5. Some or all of the ash is recycled to the viscosity-reducing cracking reactor as a dechlorination additive.

[0012] S6. The reaction oil and gas enter the separation unit and are separated to obtain 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 device, melts and dehydrates 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 gas; and the dehydrated and dechlorinated plastic raw material is directly fed into the first heating and conveying device 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 treatment. Optionally, the particle size of the plastic raw material particles is 0.5 mm to 10 mm.

[0016] Optionally, the method further includes: the hydrogen chloride-containing gas contacting 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 a portion of the first dry gas and / or at least a portion of the second dry gas entering the contact agent regenerator, so that the recycled contact agent and the charred ash undergo a complete combustion reaction in the presence of oxygen and dry gas to obtain recycled contact agent, recycled flue gas and ash and recycled flue gas; preferably, based on the total weight of the recycled contact agent, the carbon content of the recycled contact agent is 0.5% to 5.0% by weight.

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

[0019] Optionally, in step S2, the viscosity-reducing cracking reactor is an adiabatic viscosity-reducing reactor;

[0020] Preferably, the process conditions for the viscosity-reducing cracking reaction include: a reaction temperature of 360℃~490℃, preferably 370℃~420℃; and a residence time of 10min~90min, preferably 20min~60min.

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

[0022] Preferably, steam is introduced into 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 materials, quartz sand, or coal coke powder; preferably, the particle size of the contact agent is 50μm to 240μm.

[0024] Optionally, the silicon-aluminum material may or may not contain molecular sieves; wherein the molecular sieves are selected from one or more of X molecular sieves, Y molecular sieves, mordenite, ZSM-5, layered clay molecular sieves and SAPO.

[0025] Wherein, the sieve-free silica-alumina material is a catalyst prepared from one or more of the first raw materials, the first raw materials including amorphous silica-alumina, kaolin, montmorillonite, palygorskite, illite, chlorite, boehmite, and silica; or the sieve-free silica-alumina material is selected from a catalyst prepared from one or more of the second raw materials that have undergone acid washing, calcination, and sieving, the second raw materials including amorphous silica-alumina, kaolin, montmorillonite, palygorskite, illite, and chlorite; or a catalyst prepared from one or more of the second raw materials that have undergone acid washing, calcination, and sieving, together with boehmite and / or silica; optionally, the coal coke powder is coal powder and / or petroleum coke powder.

[0026] Optionally, in step S4, the charring and regeneration treatment of the waste contact agent is carried out in a contact agent regenerator; the contact agent regenerator is a dense phase fluidized bed regenerator, and the process conditions include: residence time of 0.5 seconds to 60 seconds, preferably 1.0 seconds to 10 seconds; regeneration temperature of 600℃ to 750℃, preferably 600℃ to 700℃; air or a mixture of air and inert gas is introduced; the apparent gas velocity of the dense phase fluidized bed is 0.05 m / s to 0.6 m / s, preferably 0.2 m / s to 0.4 m / 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 alkali metal compound and / or ash from the contact agent regenerator; preferably, the dechlorination additive is ash from the contact agent regenerator.

[0028] Optionally, the second heating conveying device includes a screw-type heating conveying device and a vacuum device connected to the screw-type heating conveying device; preferably, the screw-type heating conveying device is selected from a twin-screw or single-screw conveying device with heating; preferably, the process conditions of the second heating conveying device include: a first temperature of 120℃~150℃; a residence time of 0.05h~0.5h; a second temperature of 220℃~350℃; a residence time of 0.1h~0.2h; and a vacuum degree of 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% by weight; the ash content in the plastic raw material is 1% to 40% by weight, preferably 3% to 20% by weight.

[0030] Secondly, this disclosure provides a processing system for fluidized bed cracking of waste plastics, comprising a first heating liquefaction conveying device, a viscosity-reducing cracking reactor, a contact cracking reactor, a separation unit, and a contact agent regenerator connected in sequence; the first heating liquefaction conveying device includes a raw material inlet and a liquefied plastic outlet, and is configured to liquefy plastic raw materials; the plastic viscosity-reducing reactor includes a liquefied plastic inlet, a dechlorination additive inlet, a liquefied plastic oil outlet, and a first dry gas outlet, and is configured to perform viscosity-reducing cracking treatment on the liquefied plastic; the contact cracking reactor includes a cracking raw material inlet, a contact agent inlet, a reaction oil and gas outlet, and a regenerated contact agent outlet; the cracking raw material inlet is connected to the liquefied plastic inlet of the plastic viscosity-reducing reactor. The feed oil outlet is connected, and the contact cracking reactor is configured to perform cracking reaction treatment on 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 pre-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 pre-regenerated contact agent with oxygen for coke burn-off regeneration, obtaining 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 viscosity-reducing cracking reactor.

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

[0032] Optionally, a steam inlet is also included in the connecting pipeline between the feedstock inlet of the contact cracking reactor and the liquefied plastic oil outlet of the viscosity-reducing cracking reactor.

[0033] Optionally, the processing system further includes a second heating and conveying device, a hydrogen chloride absorption unit, and a cooling and pulverizing unit connected in sequence before the first heating and conveying device; the second heating and liquefaction conveying device includes a raw material inlet, a dehydrated and dechlorinated plastic outlet, and a hydrogen chloride-containing gas outlet; the second heating and liquefaction conveying device is configured to perform melting, dehydration, and dechlorination treatment on chlorinated waste plastics; the cooling and pulverizing unit is configured to perform cooling and pulverization treatment on the dehydrated and dechlorinated plastics from the second heating and liquefaction 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 liquefaction 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 single-screw or twin-screw conveying devices with heating.

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

[0037] Through the above technical solution, this disclosure provides a processing method and system for fluidized bed cracking of waste plastics. The method involves liquefying and reducing the viscosity of plastic raw materials through liquefaction and de-viscosity cracking, enabling rapid liquefaction and reduction of viscosity. Ash generated by a contact agent regenerator is used as a dechlorination additive in the de-viscosity cracking reactor for further dechlorination. This ash then contacts the fluidized contact agent for cracking, allowing the waste plastic to be processed to rapidly pyrolyze in a liquid state with the high-temperature contact agent, reducing product residence time and achieving a more ideal product distribution. It also removes heteroatoms from the plastic raw materials. By producing gaseous and liquid phase products through contact cracking, the waste plastics can be recycled in a green and resource-efficient manner, and the resulting contact agent can be regenerated and reused. Furthermore, this processing method enables continuous processing of waste plastic raw materials, improving processing efficiency. It is highly adaptable to waste plastic raw materials, eliminating the need for crushing and washing. Waste plastics from landfills can be dehydrated, dechlorinated, and reduced in volume on-site, and subsequent cracking and recycling can be centralized, facilitating large-scale production and reducing processing costs.

[0038] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0039] The accompanying drawings provide a further understanding of this disclosure and form part of the specification. They are used together with the following detailed description to explain this disclosure, but do not constitute a limitation thereof. Figure 1 A schematic diagram of the process for fluidized bed cracking of waste plastics.

[0040] In the attached diagram:

[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-Viscosity reduction cracking reactor; 6-Contact cracking reactor

[0043] 7-Contact agent regenerator; 8-Separation unit; 9-Hydrogen chloride absorption unit; 10-23-Pipelines Detailed Implementation

[0044] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0045] Firstly, this disclosure provides a method for processing waste plastics through fluidized bed cracking. Figure 1 This is a schematic diagram of the fluidized bed cracking process for waste plastics. Figure 1 As shown, it includes the following steps:

[0046] S1. Plastic raw materials enter the first heating and conveying equipment for liquefaction treatment to obtain liquefied plastic;

[0047] S2. The liquefied plastic and dechlorination additive enter the viscosity-reducing cracking reactor for viscosity-reducing cracking reaction and dechlorination to obtain liquefied plastic oil and first dry gas;

[0048] S3. The liquefied plastic oil enters the contact cracking reactor and, under dilute phase fluidized bed conditions, comes into contact with the regenerated contact agent to carry out a cracking reaction, yielding reaction oil gas, recycled contact agent, and carbonized ash.

[0049] S4. The charred ash and the unregenerated contact agent enter the contact agent regenerator, where they react with oxygen to burn off the char and regenerate, yielding regenerated contact agent, regenerated flue gas, and ash.

[0050] S5. Some or all of the ash is recycled to the viscosity-reducing cracking reactor as a dechlorination additive.

[0051] S6. The reaction oil and gas enter the separation unit and are separated to obtain 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 one 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 this disclosure can be directly sourced from waste plastics in landfills.

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

[0055] In a preferred embodiment, prior to step S1, the method further includes steps of hot melt dehydration, dechlorination, and pulverization, such as... Figure 1 As shown, the plastic raw material enters the second heating and conveying device 2, where it is melted and dehydrated under a first temperature condition of 100℃~170℃ and the residence time is 0.05h~1h. The dehydrated plastic raw material is then heated to a second temperature for dechlorination treatment, resulting in dehydrated and dechlorinated plastic raw material and hydrogen chloride gas. The second temperature is 150℃~370℃ and the residence time is 0.05h~0.5h. The dehydrated and dechlorinated plastic raw material is then directly fed into the first heating and conveying device 4 for liquefaction treatment.

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

[0057] In one specific embodiment, the melting, dehydration, and dechlorination steps and the plastic raw material liquefaction steps 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 conveyor with heating, etc.

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

[0059] Hydrogen chloride-containing gas is introduced into the hydrogen chloride absorption unit and comes into contact with the hydrogen chloride absorbent for hydrogen chloride absorption treatment; optionally, the hydrogen chloride-containing gas is introduced 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 ammonia water.

[0060] This disclosure describes a hot-melt dehydration, dechlorination, and pulverization step and a hydrogen chloride absorption step for plastic raw materials. This allows the chlorine in the waste PVC plastic in the plastic raw materials to decompose into the gas phase, and the HCl is quickly separated using a vacuum system. This avoids secondary HCl reactions, improves the dechlorination efficiency of the plastic raw materials, and reduces the corrosion pressure on subsequent equipment.

[0061] In a preferred embodiment, such as Figure 1 As shown, in step S4, the method further 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 contact agent to be recycled and the charred ash can undergo a complete combustion reaction in the presence of oxygen and dry gas to obtain recycled flue gas, recycled contact agent and ash; this disclosure uses the dry gas generated in the waste plastic processing process to regenerate the contact agent to be recycled, and the combustion of dry gas supplements the heat energy, thereby improving resource utilization efficiency and contact agent regeneration efficiency.

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

[0063] In one specific embodiment, when the regenerated flue gas meets the emission standard, the regenerated flue gas is discharged externally; wherein the emission standard for the regenerated flue gas is a conventional standard in the art, such as referring to the GB13271-2014 standard.

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

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

[0066] In one embodiment, in step S2, preferably, the viscosity-reducing cracking reactor is an adiabatic viscosity-reducing reactor. The adiabatic viscosity-reducing reactor in this disclosure can be any reactor known in the art, such as an upflow viscosity-reducing reactor or a downflow viscosity-reducing reactor.

[0067] In a preferred embodiment, the process conditions for the viscosity-reducing cracking treatment include: a reaction temperature of 380℃~500℃, preferably 390℃~450℃; and a residence time of 10min~90min, preferably 20min~60min. The preferred viscosity-reducing cracking process conditions in this embodiment can achieve a better viscosity-reducing effect.

[0068] In one embodiment, in step S3, the process conditions for the cracking reaction include: a reaction temperature of 490°C to 750°C and a weight hourly space velocity of 1 h⁻¹. -1 ~100h -1 The apparent gas velocity of the dilute phase fluidized bed is 0.3–8.0 m / s, and the mass ratio of the contact agent to the plastic raw material is 5–30:1. In this 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 process conditions for the cracking reaction include: a reaction temperature of 490℃ to 750℃, an apparent gas velocity of 1.0 to 6.0 m / s in the fluidized bed, and a mass ratio of contact agent to waste plastic to be treated of 6 to 20:1. Performing the cracking reaction according to the process conditions of this embodiment can yield a more favorable distribution of cracking products.

[0070] In a preferred embodiment, the method further includes: the liquefied plastic oil after viscosity reduction cracking and steam entering the contact cracking reactor; preferably, the mass ratio of steam to plastic raw material is 0.05 to 1:1:1, more 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 coke powder; the particle size of the contact agent can be 20μm to 3000μm, preferably 50μm to 240μm.

[0072] Optionally, the silicon-aluminum material is selected from catalysts containing molecular sieves and / or catalysts without molecular sieves; preferably, the catalyst containing molecular sieves is selected from one or more of the following molecular sieves: X molecular sieve, Y molecular sieve, mordenite, ZSM-5, layered clay molecular sieve, SAPO, and spent FCC catalysts.

[0073] Preferably, the sieve-free catalyst is selected from catalysts prepared using one or more of the first raw materials, wherein the first raw materials include amorphous silica-alumina, kaolin, montmorillonite, palygorskite, illite, chlorite, boehmite, and silica; or

[0074] The catalyst without molecular sieves is selected from catalysts prepared using one or more of the second raw materials that have undergone acid washing, calcination, and sieving treatment as raw materials, wherein the second raw materials include amorphous silica-alumina, kaolin, montmorillonite, palygorskite, illite, and chlorite; or is selected from catalysts prepared using one or more of the second raw materials that have undergone acid washing, calcination, and sieving treatment as raw materials and pseudoboehmite and / or silica.

[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-phase fluidized bed regenerator. Preferably, the regeneration process conditions include: an air residence time of 0.5 to 60 seconds, more preferably 1.0 to 10 seconds; a reaction temperature of 600°C to 750°C, more preferably 600°C to 700°C; an introduced gas containing 10% to 50% oxygen by volume; and an apparent gas velocity of 0.05 m / s to 0.6 m / s, more preferably 0.2 m / s to 0.4 m / s in the dense-phase bed. The dense-phase fluidized bed regenerator in this disclosure uses a device conventionally selected in the art.

[0077] In one embodiment, the ash portion is recycled to the viscosity-reducing cracking 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 liquefied. The dehydration and dechlorination pretreatment section 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 for the dehydration and dechlorination pretreatment include: a first temperature of 100℃~170℃, preferably 120℃~150℃; a residence time of 0.05h~1h, preferably 0.05h~0.5h; a second temperature of 150℃~370℃, preferably 220℃~350℃; a time of 0.05h~0.5h, preferably 0.1h~0.2h; and a vacuum degree of 50mmHg~300mmHg, preferably 50mmHg~150mmHg. Preferably, the heating rate from the first temperature to the second temperature is 50℃ / min~200℃ / min, preferably 50℃ / min~150℃ / min. This disclosure employs a gradual heating method, first heating to the first temperature for melting and 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 equipment. 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 specific embodiment, the dehydrated and dechlorinated plastic raw material is further subjected to cooling and pulverization to obtain processed plastic raw material granules. The particle size of the dehydrated and dechlorinated plastic raw material granules is 100μm to 2000μm. Preparing dehydrated and dechlorinated plastic raw material granules facilitates the storage and transportation of the plastic raw material.

[0081] In this disclosure, the apparatus and methods for cooling and pulverizing can be conventional apparatus and methods in the art.

[0082] The beneficial effect of the fluidized bed cracking processing method for reducing viscosity and dechlorinating waste plastics provided by this invention is that it overcomes the technical problems existing in the current field of waste plastic pyrolysis treatment. During the research process, the inventors discovered that one of the technical problems in the prior art is that polyvinyl chloride (PVC) in waste plastics, when heated and decomposed into HCl, can rapidly undergo an addition reaction with the double bonds in the raw materials to generate chlorinated hydrocarbons, making it difficult for traditional reaction devices to efficiently remove chlorine from waste plastics. To address this technical problem, this invention uses specialized equipment to rapidly heat PVC-containing materials for decomposition and uses a vacuum method to quickly separate the decomposed HCl from the reactor, thereby improving dechlorination efficiency. The second technical problem overcome in existing technologies is that plastic raw materials are high-molecular polymers. Due to their large molecular weight and solid nature, heat transfer within the plastic is very slow. Traditional heating methods cause excessive cracking of the outer layer of the plastic while the interior remains solid, resulting in a high rate of coking and high gas yield during pyrolysis. To address this second problem, specialized equipment is used to rapidly heat the waste plastic into a flowable liquid state through strong extrusion and agitation, reducing its viscosity so that it can be pumped. As the plastic raw material rapidly liquefies, the increased thermal conductivity of the liquid state allows for the use of heating furnaces or other heating equipment to pyrolyze the liquefied plastic oil, achieving a higher liquid yield and a lower coking rate. The third technical problem overcome is that the low density of plastic raw materials leads to a slow rate of entry into the reaction device, and existing technologies have a small processing scale, which cannot meet the needs of modern large-scale recycling. To address this third problem, the method provided by this invention significantly increases the transport density of the plastic raw material after liquefaction, thus enabling not only large-scale waste plastic processing but also continuous pyrolysis and recycling of plastic raw materials.

[0083] Secondly, this disclosure provides a processing system for fluidized bed cracking of waste plastics, including a first heating and conveying device, a viscosity-reducing cracking reactor, a contact cracking reactor, a separation unit, and a contact agent regenerator connected in sequence;

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

[0085] The viscosity reduction cracking reactor includes a liquefied plastic inlet, a dechlorination additive inlet, a liquefied plastic oil outlet, and a first dry gas outlet. The viscosity reduction cracking reactor is configured to perform viscosity reduction cracking treatment on liquefied plastic.

[0086] The contact cracking reactor includes a cracking feedstock inlet, a contact agent inlet, a reaction oil and gas outlet, and a standby contact agent outlet; the cracking feedstock inlet is connected to the liquefied plastic oil outlet of the viscosity-reducing cracking reactor, and the contact cracking reactor is configured to perform cracking reaction treatment 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 a pre-regenerated contact agent inlet, an oxygen-containing gas inlet, a regenerated contact agent outlet, an ash outlet, and a regenerated flue gas outlet; the contact agent regenerator is configured to react the pre-regenerated contact agent with oxygen for coke 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 viscosity-reducing cracking reactor.

[0089] In one specific embodiment, the connecting pipeline between the cracking feedstock inlet of the contact cracking reactor and the liquefied plastic oil outlet of the viscosity-reducing cracking reactor also includes a steam inlet, which helps to atomize the liquefied waste plastic oil.

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

[0091] In one 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 pulverizing 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 gas outlet; the waste plastic hot melt dehydration and dechlorination unit is configured to perform melting dehydration and dechlorination treatment on chlorinated waste plastics;

[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 device.

[0094] The cooling and pulverizing unit is configured to cool and pulverize the dehydrated and dechlorinated plastic from the second heating and conveying equipment.

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

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

[0097] In one specific embodiment, the second heating and conveying device further includes a non-condensable steam outlet for drawing out non-condensable steam.

[0098] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to 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, resulting in dehydrated and dechlorinated plastic raw materials and hydrogen chloride-containing gas. The hydrogen chloride-containing gas is drawn into the hydrogen chloride absorption unit 9 through a vacuum system to contact the hydrogen chloride absorbent for hydrogen chloride absorption treatment. A small amount of non-condensable gas is discharged through pipeline 23. The dehydrated and dechlorinated waste plastic is cooled and crushed in the cooling and crushing unit 3 in sequence to obtain pretreated plastic raw material particles, which can be stored and transported. Alternatively, the plastic raw material particles can be fed into the first heating and conveying equipment 4 for liquefaction to obtain liquefied plastic; the liquefied plastic then enters the plastic viscosity reduction reactor 5 for viscosity reduction cracking to obtain liquefied plastic oil and first dry gas; the viscosity-reduced liquefied plastic oil is sent to the contact cracking reactor 6 via pipeline 11 and steam from pipeline 10; fresh contact agent replenished from pipeline 13 and regenerated contact agent from pipeline 18 of the regenerator enter the contact cracking reactor 6; the liquefied plastic oil undergoes a cracking reaction with the fluidized contact agent in the contact cracking reactor 6 to obtain reaction oil gas and a awaited contact agent; after gas-solid separation, the reaction oil gas enters the subsequent separation unit 8 via pipeline 12 for separation processing, wherein: The second dry gas exits the unit from pipeline 22, while the liquefied petroleum gas, gasoline fraction, diesel fraction, and wax oil fraction exit the unit from pipeline 16. The carbonized pre-regenerated contact agent and optional carbonized ash enter the contact agent regenerator 7 through pipeline 14. The coke on the pre-regenerated contact agent reacts completely with the cracked 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. The generated regenerated flue gas exits the unit 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. Part of the ash is circulated from pipeline 20 to the viscosity reduction reactor for use as a dechlorination additive. The balancing agent and part of the ash are discharged from the unit.

[0100] The present disclosure is further described in detail below through examples. All raw materials used in the examples are commercially available.

[0101] The contact agent SL-1 used is a contact agent prepared by spray drying and calcination of a slurry containing 10% by weight alumina and 80% by weight kaolin. The specific preparation method is referenced in CN102974383A. The average particle size of SL-1 is 80μm.

[0102] The second contacting agent used is a catalytic cracking balance agent with the brand name CRC-1 (produced by Qilu Petrochemical Company), and the average particle size is 65μm.

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

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

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

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

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

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

[0109] The density analysis method for diesel and wax oil is SH / T0604-2000; the composition of cracked gases is determined by the RIPP 78-90 method; and the hydrocarbon composition of naphtha, diesel, etc., is determined by chromatographic analysis.

[0110] In the following embodiments, the particle size range of the particles obtained after pulverization is 5 to 8 mm.

[0111] Example 1

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

[0113] Liquefaction process: The plastic raw material is fed into a twin-screw heated conveyor for liquefaction. The feed rate is 100 kg / h, the outlet temperature of the twin-screw heated conveyor is 390℃, and the residence time is 12 min. The resulting liquefied plastic LP-1 is shown in Table 1.

[0114] Viscosity reduction cracking step: Using an adiabatic viscosity reduction reactor, the liquefied plastic was introduced into the reactor via a screw pump for viscosity reduction cracking treatment. The viscosity reduction reaction temperature was 390℃, and the reaction time was 60 min, yielding a viscosity-reduced cracked liquefied plastic oil. The chlorine content was analyzed, and the viscosity was tested.

[0115] The contact cracking reactor is a riser reactor, with quartz sand as the contact agent. Liquefied plastic oil and steam enter the riser reactor from the bottom, while quartz sand enters from the bottom and flows upward under the lift of the riser gas. The liquefied plastic oil and contact agent flow upward and undergo cracking reaction. At the top of the reactor, gas-solid separation is achieved to obtain reaction oil and gas and the remaining contact agent. The reaction oil and gas are further separated, with the mass ratio of contact agent to plastic raw material being 7:1. The cracking reaction process conditions are: reaction temperature of 510℃, apparent gas velocity of 6.0 m / s, and mass ratio of steam to plastic raw material of 0.4:1.

[0116] Contact agent regeneration steps: The contact agent regenerator is a dense-phase fluidized bed reactor. The raw contact agent (containing 1.3% carbon by weight) and air are introduced into the regenerator for coking and regeneration. The regeneration temperature is 660℃, the apparent gas velocity in the dense-phase bed is 0.3 m / s, and the contact agent residence time is 3 s. The resulting regenerated contact agent is returned to the contact cracking reactor for recycling. First dry gas from the viscosity-reducing reactor and second dry gas from the separation unit are introduced into the contact agent regenerator to react with oxygen to regulate the regeneration temperature.

[0117] The ash obtained from the recycling unit was recycled to the viscosity-reducing reactor as a dechlorination additive, with a recycled ash to plastic raw material weight ratio of 0.035:1. The chlorine content of the liquefied plastic oil was analyzed again under the same viscosity-reducing reaction conditions (reaction temperature 390℃, reaction time 60 min). The product distribution of the cracking reaction products is shown in Table 4. The ash composition and chlorine content of the viscosity-reducing products are shown in Tables 5 and 6.

[0118] Example 2

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

[0120] The same twin-screw heating conveyor with segmented temperature control is used to dehydrate, dechlorinate, and liquefy plastic raw materials.

[0121] Dehydration and dechlorination steps: The plastic raw material is fed into a twin-screw heating conveyor at a feed rate of approximately 5 kg / h. It is melted and dehydrated at a first temperature of 150°C and a residence time of 0.1 h. It is then dechlorinated at a second temperature of 300°C and a residence time of 0.1 h, with a heating rate of 100°C / min from the first temperature to the second temperature. The twin-screw heating conveyor is connected to a vacuum pump with a vacuum degree of 150 mmHg, resulting in dehydrated and dechlorinated plastic raw material.

[0122] Liquefaction process: The dehydrated and dechlorinated plastic raw materials were liquefied using the same twin-screw heated conveyor. The outlet temperature of the twin-screw heated conveyor is listed in Table 2. The residence time was 12 min. The resulting liquefied plastics were LP-2a, LP-2b, LP-2c, and LP-2d. The composition of liquefied plastic LP-2b is shown in Table 1.

[0123] Viscosity reduction cracking step: The liquefied plastics obtained by liquefaction treatment at different temperatures were subjected to viscosity reduction cracking treatment to obtain liquefied plastic oils 1-8 under 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℃, reaction time 60min) was used as the cracking feedstock. The contact cracking reactor adopted a riser reactor. The contact agent SL-1 entered the riser reactor from the bottom under the riser gas. The liquefied plastic oil and steam entered the riser reactor and flowed upward with the fluidized contact agent to carry out the cracking reaction, obtaining reaction oil gas and recycled contact agent. At the top of the riser reactor, the reaction oil gas entered the gas-solid separation device for gas-solid separation. The separated reaction oil gas was further separated, and the recycled contact agent and carbon ash were sent to the contact agent regenerator for coking and regeneration.

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

[0126] The regeneration steps for the recycled contact agent and the carbonized ash are the same as in Example 1. The ash obtained from the regeneration unit is recycled to the viscosity-reducing reactor as a dechlorination additive. The weight ratio of recycled ash to plastic raw material is 0.035:1. The chlorine content of liquefied plastic oil 4 under the same viscosity-reducing reaction conditions (reaction temperature 390℃, reaction time 60min) is analyzed again. The product distribution of the cracking reaction products is shown in Table 4. The ash composition and chlorine content of the viscosity-reducing products are shown in Tables 5 and 6.

[0127] Table 1 Composition and content of plastic raw materials and liquefaction treatment

[0128] Preprocessing steps / / Melting, dehydration, and dechlorination treatment Liquefaction process / Feed rate, kg / h / 100 5 Outlet temperature, °C / 390 390 Dwell time, min / 12 12 Composition and 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 oils obtained under liquefaction treatment and viscosity reduction reaction conditions in Example 2. In the table, a "-" 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℃, reaction time 60min) after viscosity reduction treatment in Example 2 was used as the cracking feedstock.

[0132] The same process as in Example 2 was used, with SL-1 as the contact agent. The difference was that the ash obtained from the contact agent regenerator was recycled to the viscosity-reducing cracking reactor as a dechlorination additive, with a weight ratio of recycled ash to plastic raw material of 0.04:1. The product distribution of the cracking reaction products is shown in Table 4. The chlorine content of the viscosity-reducing 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 conveyor was used as the melting, dehydration, and dechlorination equipment. The feed rate of the plastic raw material was approximately 5 kg / h. The process conditions for melting, dehydration, and dechlorination were as follows: the first temperature was 150℃; the residence time was 0.1 h; the second temperature was 300℃; the residence time was 0.1 h; the heating rate from the first temperature to the second temperature was 100℃ / min; and the vacuum degree of the screw heating conveyor was 150 mmHg. Dehydrated and dechlorinated plastic raw material was obtained.

[0136] The same twin-screw heated conveyor was used to liquefy the dehydrated and dechlorinated plastic raw material to obtain liquefied plastic LP-3, the properties of which are shown in Table 1. The liquefaction process conditions were: outlet temperature of the twin-screw heated conveyor 390℃ and residence time of 12min. The obtained liquefied waste plastic was then subjected to viscosity reduction cracking treatment. The viscosity reduction cracking treatment process conditions included: reaction temperature of 390℃ and reaction time of 60min, to obtain liquefied plastic oil LP-3-60.

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

[0138] Table 3 Composition and content of plastic raw materials and liquefaction treatment

[0139] Preprocessing steps / Melting, dehydration, and dechlorination treatment Liquefaction process / Feed rate, kg / h / 5 Outlet temperature, °C / 390 Dwell time, min / 12 Composition and 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] Using the liquefied plastic oil LP-3-60 obtained in Example 4 as raw material, the same process as in Example 5 was adopted, except that contact agent CRC-1 was used. The liquefied plastic oil and steam obtained from viscosity reduction cracking were introduced into the contact cracking reactor (riser reactor) and contacted with the fluidized contact agent to carry out the cracking reaction, obtaining reaction oil gas and raw contact agent. The mass ratio of contact agent to plastic raw material was 7:1. The process conditions for the cracking reaction included: reaction temperature of 500℃, apparent gas velocity of 4.0 m / s, and mass ratio of steam to 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 viscosity reduction products before and after ash recycling is shown in Table 5.

[0142] Table 4 Distribution of pyrolysis products

[0143]

[0144] As can be seen from the data in Table 4, when the process flow and conditions of this disclosure are met, the yield of the C5-180℃ fraction is 53.33%-63.20% by weight.

[0145] Table 5 Ash Content Composition

[0146]

[0147]

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

[0149] 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 Viscosity-reducing cracking 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 content and chlorine content (ppm) 66.00 23.00 18.00 123.50 132.00 Ash content to raw material weight ratio 0.035 0.035 0.04 0.035 0.035

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

Claims

1. A method for fluidized bed cracking of waste plastics, characterized in that, Includes the following steps: S1. Plastic raw materials enter the first heating and conveying equipment for liquefaction treatment to obtain liquefied plastic; S2. The liquefied plastic and dechlorination additive enter the viscosity-reducing cracking reactor for viscosity-reducing cracking reaction and dechlorination to obtain liquefied plastic oil and first dry gas; S3. The liquefied plastic oil enters the contact cracking reactor and, under dilute phase fluidized bed conditions, contacts a high-temperature contact agent to carry out a cracking reaction, yielding reaction oil gas, unused contact agent, and carbonized ash. The process conditions for the cracking reaction include: a reaction temperature of 490℃~750℃ and a mass ratio of contact agent to plastic raw material of 5~30:

1. S4. The recycled contact agent and carbonized ash enter the contact agent regenerator, react with oxygen to burn off the coke and regenerate, and obtain recycled contact agent, recycled flue gas and ash. The process conditions of the contact agent regenerator include: regeneration temperature of 600℃~750℃, and air or a mixture of air and inert gas is introduced. S5. Some or all of the ash is recycled to the viscosity-reducing cracking reactor as a dechlorination additive. S6. The reaction oil and gas enter the separation unit and are separated to obtain second dry gas, liquefied gas, gasoline fraction, diesel fraction and wax oil fraction; In step S2, the weight ratio of the dechlorination additive to the liquefied plastic is (0.025~0.045):

1.

2. The waste plastic fluidized bed cracking processing method according to claim 1, characterized in that, Before step S1, the method further includes: The plastic raw material enters the second heating and conveying equipment, where it is melted and dehydrated at the first temperature to obtain dehydrated plastic raw material. Then, it is heated to the second temperature for dechlorination treatment to obtain dehydrated and dechlorinated plastic raw material and hydrogen chloride gas. The dehydrated and dechlorinated plastic raw material is then directly fed into the first heating and conveying equipment for liquefaction treatment.

3. The waste plastic fluidized bed cracking processing method according to claim 2, characterized in that, The dehydrated and dechlorinated plastic raw material is cooled and crushed sequentially in the cooling and crushing unit to obtain dehydrated and dechlorinated plastic raw material particles; the dehydrated and dechlorinated plastic raw material particles are then fed into the first heating and conveying equipment.

4. The waste plastic fluidized bed cracking processing method according to claim 3, characterized in that, The particle size of the plastic raw material particles is 100μm to 2000μm.

5. The waste plastic fluidized bed cracking processing method according to claim 2, 3 or 4, characterized in that, The method also includes: The hydrogen chloride-containing gas is contacted with 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; 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.

6. The waste plastic fluidized bed cracking processing method according to any one of claims 1-4, characterized in that, In step S4, the method further includes: At least a portion of the first dry gas and / or at least a portion of the second dry gas are introduced into the contact agent regenerator, so that the unregenerated contact agent and the charred ash react completely in the presence of oxygen and dry gas to obtain regenerated contact agent, regenerated flue gas and ash.

7. The waste plastic fluidized bed cracking processing method according to claim 6, characterized in that, Based on the total weight of the contacting agent, the carbon content of the prepared contacting agent is 0.5~5.0% by weight.

8. The waste plastic fluidized bed cracking processing method according to any one of claims 1-4, characterized in that, In step S1, the first heating and conveying device is selected from a screw-type heating and conveying device; the process conditions for the liquefaction treatment include: an outlet temperature of 380℃~500℃; and a residence time of 5 min~30 min.

9. The waste plastic fluidized bed cracking processing method according to claim 8, characterized in that, In step S1, the first heating conveying device is selected from a twin-screw or single-screw heating conveying device with heating; the process conditions for the liquefaction treatment include: an outlet temperature of 400℃~450℃; and a residence time of 5 min~15 min.

10. The fluidized bed cracking processing method for waste plastics according to any one of claims 1-4, characterized in that, In step S2, the viscosity-reducing cracking reactor is an adiabatic viscosity-reducing reactor; The process conditions for the viscosity-reducing cracking reaction include: a reaction temperature of 360℃~490℃; and a residence time of 10 min~90 min.

11. The waste plastic fluidized bed cracking processing method according to claim 10, characterized in that, In step S2, the process conditions for the viscosity-reducing cracking reaction include: a reaction temperature of 370℃~420℃; and a residence time of 20 min~60 min.

12. The waste plastic fluidized bed cracking processing method according to any one of claims 1-4, characterized in that, In step S3, the process conditions for the cracking reaction include: the apparent gas velocity of the dilute phase fluidized bed is 0.3~8.0 m / s; Steam is introduced into the contact cracking reactor; the mass ratio of steam to plastic raw material is 0.05~1:

1.

13. The waste plastic fluidized bed cracking processing method according to claim 12, characterized in that, In step S3, the process conditions for the cracking reaction include: a reaction temperature of 500℃~650℃, an apparent gas velocity of 1.0~6.0m / s in the dilute phase fluidized bed, and a mass ratio of contact agent to plastic raw material of 6~20:

1.

14. The waste plastic fluidized bed cracking processing method according to claim 12, characterized in that, In step S3, the mass ratio of steam to plastic raw material is 0.1~0.5:

1.

15. The fluidized bed cracking processing method for waste plastics according to any one of claims 1-4, 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.

16. The waste plastic fluidized bed cracking processing method according to claim 15, characterized in that, In step S3, the particle size of the contact agent is 50 μm to 250 μm; The silicon-aluminum material may or may not contain molecular sieves; wherein the molecular sieves are selected from one or more of X molecular sieves, Y molecular sieves, mordenite zeolite, ZSM-5, layered clay molecular sieves and SAPO; and the coal coke powder is coal powder and / or petroleum coke powder.

17. The waste plastic fluidized bed cracking processing method according to any one of claims 1-4, characterized in that, In step S4, the contact agent regenerator is a dense-phase fluidized bed reactor, and the process conditions include: residence time of 0.5 seconds to 60 seconds and apparent gas velocity of 0.05 m / s to 0.6 m / s in the dense-phase bed.

18. The waste plastic fluidized bed cracking processing method according to claim 17, characterized in that, The contact agent regenerator process conditions in step S4 include: residence time of 1.0 to 10 seconds, regeneration temperature of 600°C to 700°C, and apparent gas velocity of the dense phase bed of 0.2 m / s to 0.4 m / s.

19. The waste plastic fluidized bed cracking processing method according to any one of claims 1-4, characterized in that, In step S2, the weight ratio of the dechlorination additive to the liquefied plastic is (0.03~0.04):

1.

20. The waste plastic fluidized bed cracking processing method according to claim 2, 3 or 4, 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.

21. The fluidized bed cracking method for processing waste plastics according to claim 20, characterized in that, The screw-type heated conveyor is selected from twin-screw or single-screw conveyors with heating.

22. The fluidized bed cracking processing method for waste plastics according to claim 20, characterized in that, The process conditions for the second heating and conveying equipment include: a first temperature of 100℃~170℃; a residence time of 0.05 h~1 h; a second temperature of 150℃~370℃; a residence time of 0.05 h~0.5 h; and a vacuum degree of 50 mmHg~300 mmHg. The heating rate from the first temperature to the second temperature is 50℃ / min ~ 200℃ / min.

23. The waste plastic fluidized bed cracking processing method according to claim 20, characterized in that, The process conditions for the second heating and conveying equipment include: a first temperature of 120℃~150℃; a residence time of 0.05 h~0.5 h; a second temperature of 220℃~350℃; a residence time of 0.1 h~0.2 h; and a vacuum degree of 50 mmHg~150 mmHg. The heating rate from the first temperature to the second temperature is 50℃ / min ~ 150℃ / min.

24. The waste plastic fluidized bed cracking processing method according to any one of claims 1-4, characterized in that, The plastic raw material is selected from one or more of LDPE, HDPE, PS, PP, PET and PVC.

25. The waste plastic fluidized bed cracking processing method according to claim 24, characterized in that, The chlorine content of the plastic raw material is less than 10% by weight; the ash content is 1% to 40% by weight.

26. The waste plastic fluidized bed cracking processing method according to claim 25, characterized in that, The ash content is 3% to 20% by weight.

27. A waste plastic fluidized bed cracking processing system, used in the waste plastic fluidized bed cracking processing method according to any one of claims 1-26, characterized in that, It includes a first heating and conveying device, a viscosity-reducing cracking reactor, a contact cracking reactor, a separation unit, and a contact agent regenerator connected in sequence; The first heating conveying device includes a raw material inlet and a liquefied plastic outlet, and the first heating conveying device is configured to liquefy plastic raw materials. The viscosity reduction cracking reactor includes a liquefied plastic inlet, a dechlorination additive inlet, a liquefied plastic oil outlet, and a first dry gas outlet. The viscosity reduction cracking reactor is configured to perform viscosity reduction cracking treatment on liquefied plastic. The contact cracking reactor includes a cracking feedstock inlet, a contact agent inlet, a reaction oil and gas outlet, and a standby contact agent outlet; the cracking feedstock inlet is connected to the liquefied plastic oil outlet of the viscosity-reducing cracking reactor, 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 contact agent regenerator includes a pre-regenerated contact agent inlet, an oxygen-containing gas inlet, a regenerated contact agent outlet, an ash outlet, and a regenerated flue gas outlet; the contact agent regenerator is configured to react the pre-regenerated contact agent with oxygen for coke 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 viscosity-reducing cracking reactor.

28. The waste plastic fluidized bed cracking processing system according to claim 27, characterized in that, Before the first heating and conveying device, there are also a second heating and conveying device, a hydrogen chloride absorption unit, and a cooling and pulverizing unit connected in sequence; The second heating and conveying equipment includes a raw material inlet, a dehydrated and dechlorinated plastic outlet, and a hydrogen chloride gas outlet; the waste plastic hot melt dehydration and dechlorination unit is configured to perform melting dehydration and dechlorination treatment on chlorinated waste plastics; 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 device. The cooling and pulverizing unit is configured to cool and pulverize the dehydrated and dechlorinated plastic from the second heating and conveying equipment.

29. The waste plastic fluidized bed cracking processing system according to claim 27 or 28, characterized in that, The contact agent regenerator further includes a dry gas inlet, which is connected to the first dry gas outlet of the viscosity-reducing cracking reactor and / or the second dry gas outlet of the separation unit. The connecting pipeline between the feedstock inlet of the contact cracking reactor and the liquefied plastic oil outlet of the viscosity-reducing cracking reactor also includes a steam inlet. The first heating conveying device is a screw-type heating conveying device; the second heating conveying device is a screw-type heating conveying device and a vacuum device connected to the screw-type heating conveying device; the screw-type heating conveying device is selected from single-screw or twin-screw heating conveying devices with heating.

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