CN-116120960-B - System and method for preparing liquid hydrocarbon from waste plastics

CN116120960BCN 116120960 BCN116120960 BCN 116120960BCN-116120960-B

Abstract

The application relates to a method for preparing liquid hydrocarbon from waste plastics, which comprises the following steps of S1, mixing waste plastics and a pyrolysis catalyst to obtain a first mixture, S2, carrying out multistage pyrolysis reaction on the first mixture to obtain a first mixed oil-gas component and a first solid product, S3, separating the first mixed oil-gas component and the first solid product, S4, carrying out catalytic recombination on the first mixed oil-gas component to obtain a second mixed oil-gas component, and S5, carrying out fractional distillation refining on the second mixed oil-gas component to obtain gaseous hydrocarbon and liquid hydrocarbon. The application also relates to a system for preparing liquid hydrocarbons from waste plastics. The application solves the technical problem of chemical recycling of waste plastics, ensures that the waste plastics are catalytically converted into more industrial raw materials, solves the problem of environmental pollution caused by burning the waste plastics in the market, improves the utilization value of the waste plastic cracking catalyst, and brings great economic and social benefits to petrochemical industry.

Inventors

XIN BENEN
MENG JIAN
XUE TAO
LI JINCHENG

Assignees

浙江科茂环境科技有限公司

Dates

Publication Date: 20260505
Application Date: 20230316

Claims (7)

1. A method for producing liquid hydrocarbons from waste plastics, said method comprising the steps of: S1, mixing waste plastics and a pyrolysis catalyst to obtain a first mixture, wherein the waste plastics comprise PP, PE, PET, PVC, PS and nylon; s2, carrying out multistage pyrolysis reaction on the first mixture to obtain a first mixed oil gas component and a first solid product, wherein the multistage pyrolysis reaction comprises the steps of sequentially carrying out three-stage pyrolysis reaction on the first mixture, wherein the temperature of the first-stage pyrolysis reaction is 350-400 ℃, the temperature of the second-stage pyrolysis reaction is 400-450 ℃, and the temperature of the third-stage pyrolysis reaction is 450-550 ℃; s3, separating the first mixed oil-gas component and a first solid product; S4, carrying out catalytic recombination on the first mixed oil gas component to obtain a second mixed oil gas component, wherein the catalytic recombination comprises the steps of recombining olefin and diene in the first mixed oil gas component to generate alkane and arene, and/or overlapping short-chain olefin into long-chain olefin; S5, fractionating and refining the second mixed oil gas component to obtain gaseous hydrocarbon with carbon number less than or equal to 4 and first part of liquid hydrocarbon with carbon number greater than or equal to 5; And S6, carrying out a superposition reaction on the gaseous hydrocarbon to obtain a second part of liquid hydrocarbon, wherein the carbon number of the second part of liquid hydrocarbon is greater than or equal to 5.
2. The method of claim 1, further comprising the step of: and S7, after the step S3 and before the step S4, dedusting and impurity removing are carried out on the first mixed oil gas component.
3. The method of claim 2, wherein said step S7 and said step S4 are performed in the same apparatus.
4. The method of claim 1, wherein in the step S1, the mixing of the waste plastics and the pyrolysis catalyst includes mixing the waste plastics and the pyrolysis catalyst under heating to melt the waste plastics.
5. A system for producing liquid hydrocarbons from waste plastics, the system comprising: The mixing device is used for mixing waste plastics and a pyrolysis catalyst to obtain a first mixture, wherein the waste plastics comprise PP, PE, PET, PVC, PS and nylon; The first reaction device is used for pyrolyzing the first mixture to obtain a first mixed oil gas component and a first solid product, and comprises a primary pyrolysis device, a secondary pyrolysis device and a tertiary pyrolysis device, wherein the temperature of the primary pyrolysis device is 350-400 ℃, the temperature of the secondary pyrolysis device is 400-450 ℃, and the temperature of the tertiary pyrolysis device is 450-550 ℃; a first separation device for separating the first mixed oil and gas component and a first solid product; The second reaction device is used for carrying out catalytic recombination on the first mixed oil gas component to obtain a second mixed oil gas component; catalytically recombining the first mixed oil and gas component comprises recombining olefins and diolefins in the first mixed oil and gas component to produce paraffins and aromatics, and/or overlapping short-chain olefins to long-chain olefins; The second separation device is used for fractionating and refining the second mixed oil gas component to obtain gaseous hydrocarbon with the carbon number less than or equal to 4 and first part of liquid hydrocarbon, and the carbon number of the first part of liquid hydrocarbon is more than or equal to 5; and the third reaction device is used for carrying out the superposition reaction on the gaseous hydrocarbon to obtain a second part of liquid hydrocarbon, and the carbon number of the second part of liquid hydrocarbon is more than or equal to 5.
6. The system of claim 5, wherein the system further comprises: The dust removing and impurity removing device is used for removing dust and impurities from the first mixed oil gas component, is arranged at the downstream of the first separating device and is arranged at the upstream of the second reacting device.
7. The system of claim 6, wherein the dedusting and impurity removal device and the second reaction device are an integrated device.

Description

System and method for preparing liquid hydrocarbon from waste plastics Technical Field The application relates to the technical field of garbage disposal and chemical recovery of waste plastics, in particular to a system and a method for preparing liquid hydrocarbon from waste plastics. Background The plastic market demand of China is increased year by year, about 4000 ten thousand tons of waste plastic are produced annually, and the recycling rate is low. At present, waste plastic treatment means are gradually changed from landfill and incineration to recycling mainly including physical recycling, chemical recycling and the like. However, because the composition and the sources of the waste plastics are complex, the waste plastics can severely corrode equipment in the pyrolysis process, the environmental pollution is large, the yield fluctuation of the plastic pyrolysis oil is large, the property is unstable, and the impurity content of micromolecular organic chlorine, organic silicon and the like in the oil product is up to thousands of times of that of petroleum products. Therefore, the plastic oil cannot be directly used as petrochemical product and needs to be further processed. For this reason, there is a need in the art for a system and method for producing liquid hydrocarbons from waste plastics. Disclosure of Invention The application aims to provide a method for preparing liquid hydrocarbon from waste plastics. Specifically, the method comprises the steps of subjecting waste plastics to multistage pyrolysis to obtain a first mixed oil-gas component, then carrying out catalytic recombination on the first mixed oil-gas component to obtain a second mixed oil-gas component, and obtaining C1-C4 gas hydrocarbon and liquid hydrocarbon above C5 after fractional distillation and refining. Preferably, the C1-C4 gaseous hydrocarbons may be subjected to a polymerization reaction to yield additional C5 or higher liquid hydrocarbons, thereby maximizing the yield of liquid hydrocarbons. It is also an object of the present application to provide a system for producing liquid hydrocarbons from waste plastics. In order to solve the technical problems, the application provides the following technical scheme. In a first aspect, the present application provides a process for the preparation of liquid hydrocarbons from waste plastics comprising the steps of: S1, mixing waste plastics and a pyrolysis catalyst to obtain a first mixture; s2, carrying out multistage pyrolysis reaction on the first mixture to obtain a first mixed oil gas component and a first solid product; s3, separating the first mixed oil-gas component and a first solid product; S4, carrying out catalytic recombination on the first mixed oil gas component to obtain a second mixed oil gas component; And S5, carrying out fractional distillation refining on the second mixed oil gas component to obtain gaseous hydrocarbon with the carbon number less than or equal to 4 and first part of liquid hydrocarbon with the carbon number greater than or equal to 5. In a second aspect, the application provides a system for preparing liquid hydrocarbon from waste plastics, which comprises a mixing device, a first reaction device, a first separation device and a second reaction device, wherein the mixing device is used for mixing waste plastics and a pyrolysis catalyst to obtain a first mixture, the first reaction device is used for pyrolyzing the first mixture to obtain a first mixed oil gas component and a first solid product, the first separation device is used for separating the first mixed oil gas component and the first solid product, the second reaction device is used for carrying out catalytic recombination on the first mixed oil gas component to obtain a second mixed oil gas component, and the second separation device is used for fractional distillation refining on the second mixed oil gas component to obtain gaseous hydrocarbon with carbon number less than or equal to 4 and liquid hydrocarbon of a first part, and the carbon number of the liquid hydrocarbon of the first part is greater than or equal to 5. Compared with the prior art, the application has the beneficial effects that the waste plastics can be efficiently converted into oil gas components through multistage pyrolysis reaction, and after the catalytic recombination reaction is carried out, gaseous hydrocarbon and liquid hydrocarbon can be obtained. Further, by subjecting the gaseous hydrocarbons to a polymerization reaction, additional liquid hydrocarbons are obtained, whereby the yield of liquid hydrocarbons can be maximized. The application solves the technical problem of chemical recycling of waste plastics, ensures that the waste plastics are catalytically converted into more industrial raw materials, solves the problem of environmental pollution caused by burning the waste plastics in the market, improves the utilization value of the waste plastic cracking catalyst, and brings great economic and