Plastic Pyrolysis Wax Production for Higher Light Wax Yield
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Solution Overview
Problem
Existing pyrolysis processes for producing waxes from plastics often prioritize heavy waxes, leading to inefficiencies in producing lighter waxes and requiring energy-intensive separation processes.
Innovation Solution
A process involving pyrolysis in a temperature-controlled rotary kiln followed by hydrogenation of the pyrolysis products, allowing for the production of light waxes with melting points less than 100°C, which can be efficiently separated from lighter hydrocarbons without the need for additional energy-intensive fractionation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If pyrolysis processes are designed to maximize the yield of C20+ products overall, then the total wax production is increased, but the distribution shifts towards increased proportions of heavy waxes at the expense of light waxes
Solution Approach 1:
The patent applies parameter changes by modifying the pyrolysis conditions (temperature, pressure, residence time) and introducing hydrogenation treatment to alter the product distribution. Specifically, hydrogenation converts olefinic bonds to saturated bonds, changing the chemical composition and enabling better separation of light waxes from the product stream, thus resolving the contradiction between total wax yield and light wax proportion.
2Quantity of substance
If vacuum pyrolysis is used to increase the proportion of waxes, then heavy waxes are produced more efficiently, but the production of light waxes is detrimental
Solution Approach 1:
The patent introduces hydrogenation as an intermediary process between pyrolysis and wax separation. This intermediary step converts the olefinic pyrolysis products into saturated hydrocarbons, which have different separation characteristics. This allows light waxes to be more efficiently separated from the product stream, resolving the contradiction between increasing overall wax proportion and maintaining light wax yield.
3Quantity of substance
If processes are designed to shift distribution towards lighter products, then light fraction production is increased, but there are increased losses in non-condensable gas
Solution Approach 1:
The patent optimizes pyrolysis parameters (temperature, pressure, residence time) to achieve a balanced product distribution that maximizes light fraction production while minimizing non-condensable gas formation. The hydrogenation step further converts gaseous olefins into condensable saturated hydrocarbons, reducing gas losses and improving light fraction yield simultaneously.
4Manufacturing precision
If separation processes are used to isolate light waxes from liquid products, then light wax purity is improved, but energy-intensive fractionation is required
Solution Approach 1:
The patent uses hydrogenation as an intermediary treatment that simplifies the subsequent separation process. By converting olefins to saturated hydrocarbons, the physical and chemical properties of the products are altered, enabling more efficient separation of light waxes with lower energy consumption. This resolves the contradiction between achieving high light wax purity and reducing separation energy requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process achieves an increased yield of light waxes with melting points less than 100°C, enabling their efficient separation and production of valuable product streams with reduced energy consumption.
Implementation Method 1
Pyrolysis is the thermal decomposition of materials at elevated temperatures in the absence of oxygen. Thus, no combustion or oxidation takes place. In plastic pyrolysis, the plastic wastes are heated to elevated temperatures to degrade the wastes into combustible gases, liquid and solid products.
Implementation Method 2
passing a liquid fraction of the fluid product stream comprising C5+ hydrocarbons to a hydrogenation reactor and hydrogenating said liquid fraction
Data Source
AI summary
The present invention relates to producing hydrocarbon products from a polymer feed. In particular, the present invention relates to producing waxes from a polymer feed by pyrolysis and hydrogenation of a fluid product stream from the pyrolysis.