Polyolefin waste plastic self-exothermic phase change thermal cracking process

Abstract

The invention relates to the technical field of waste plastic recycling, and particularly discloses a polyolefin waste plastic self-exothermic phase change thermal cracking process which comprises the following steps: placing polyolefin waste plastic in a high-pressure reactor, and introducing inert gas to replace air in the high-pressure reactor; inputting a phase construction agent into the high-pressure reactor, wherein the phase construction agent comprises inert gas with an initial pressure value greater than 0.5 MPa and / or hydrocarbon liquid with a boiling point lower than 125 DEG C; heating the high-pressure reactor to 340-380 DEG C, enabling the pressure value in the high-pressure reactor to be 2-6 MPa, subjecting the polyolefin waste plastic to a self-exothermic phase change thermal cracking reaction, and obtaining a thermal cracking product. The self-exothermic phase change of the polyolefin waste plastic long-chain hydrocarbon is realized by establishing a specific phase state condition, so that the thermal cracking reaction temperature is greatly increased, the deep cracking of the polyolefin waste plastic is promoted, and the energy consumption in the heat treatment process can be obviously reduced.

Description

technical field [0001] The invention relates to the technical field of recycling waste plastics, in particular to a self-exothermic phase-change pyrolysis process for polyolefin waste plastics. Background technique [0002] According to statistics, as of 2015, the total global plastic production has reached 6.3 billion tons; another scholar predicts that the current annual growth rate of plastic production is about 4%, which means that more plastic waste will be generated; and statistics show that, Only about 9% of plastic waste is recycled, 12% is incinerated, and 79% flows into terrestrial and marine ecosystems, ultimately endangering the health of various organisms including humans. Although incineration treatment can achieve heat recovery, based on the current global annual output of waste plastics of 260 million tons, if all of them flow to incineration, the potential CO 2 Emissions, about three times the mass of plastic, are equivalent to about 2% of total global carb...

AI Technical Summary

Problems solved by technology

In addition, the performance of plastics degrades after repeated melting and recycling, so mechanical recycling technology cannot be used as the ultimate way to eliminate white pollution

[0003] The traditional pyrolysis technology generally adopts the process of catalytic pyrolysis, which has the disadvantages of high process temperature, long reaction time, and low added value of the product. The complete thermal conversion of waste plastics into product oil requires a temperature condition of at least 430°C-550°C

In the process of catalytic pyrolysis, the catalyst is mixed with the raw materials, and the carbon residue generated by the thermal conversion of waste plastics sticks to the surface of the catalyst, which makes the catalyst easily deactivated and difficult to recycle and reuse, increasing the operating cost

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