Hydroprocessing Reactor for Plastic Waste Effluent
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Solution Overview
Problem
Hydrothermal liquefaction (HTL) of plastic waste generates hydrocarbon effluent with high impurity levels, including silicon, chlorides, metals, and heteroatoms, which are detrimental to downstream units and require additional energy for removal, making the process economically challenging for small-scale operations.
Innovation Solution
A method for treating hydrocarbon effluent from HTL of plastic waste involves a hydroprocessing unit using supercritical water to convert mixed plastic waste into stable hydrocarbon products, which includes a pre-treatment section to remove impurities and a continuous mixed settler vessel to stabilize the suspension and prevent agglomeration, thereby eliminating the need for a separate diolefins saturation reactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate diolefins saturation reactor is used to remove dienes from waste plastics oil, then polymerization is prevented, but device complexity and capital costs increase
Solution Approach 1:
The patent combines the diolefins saturation function with the main hydroprocessing reactor by operating the single reactor at dual temperature zones: a first temperature zone (≤210°C) for diolefins saturation and a second temperature zone (>210°C) for hydroprocessing. This integration eliminates the need for a separate diolefins saturation reactor while maintaining effective removal of reactive dienes to prevent polymerization.
Solution Approach 2:
The single hydroprocessing reactor is designed to perform multiple functions simultaneously: it acts as both a diolefins saturation unit (at lower temperatures) and a hydroprocessing unit (at higher temperatures). This multi-functional design allows one reactor to replace what would traditionally require two separate reactors, reducing capital costs and system complexity.
2Manufacturing precision
If multiple impurities are removed from hydrocarbon effluent, then product quality improves, but use of energy increases
Solution Approach 1:
The patent employs variable temperature parameters throughout the hydroprocessing process to efficiently remove different types of impurities. By adjusting temperatures between the first zone (≤210°C) for diolefins saturation and the second zone (>210°C) for hydroprocessing, the system optimizes energy usage to achieve comprehensive impurity removal without excessive energy consumption.
3Productivity
If high temperature and pressure conditions are used in HTL process, then conversion efficiency improves, but capital and operating costs increase
Solution Approach 1:
The patent utilizes temperature parameter changes within the hydroprocessing reactor, operating at a first temperature zone (≤210°C) for diolefins saturation and a second temperature zone (>210°C) for hydroprocessing. This staged temperature approach achieves effective conversion and impurity removal while optimizing energy consumption and reducing operational costs compared to continuously operating at maximum HTL conditions.
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
This method achieves near-complete conversion of plastic waste into hydrocarbons, reduces diolefin formation, and simplifies the hydro treatment process, resulting in a clean liquid fuel product with reduced capital and operating costs.
Implementation Method 1
Hydrothermal liquefaction (HTL) is a thermochemical process that can convert biomass or organic waste into a liquid bio-oil under high temperature and pressure
Implementation Method 2
The process is like that used in pyrolysis process, but with some differences in the operating conditions and the use of supercritical water
Implementation Method 3
Most refiners use separate di-olefins reactor to saturate dienes in the waste plastics oil
Implementation Method 4
An internal skewed blade type mixed with blades or any agitator may be used in the continuous mixed settler vessel to establish a stable suspension
Implementation Method 5
Finally, the separator effluent is passed to a distillation section for extracting a liquid fuel product stream
Data Source
AI summary
A method for treating effluent from hydrothermal liquification of feedstock that contains plastic oil, pyrolysis oil, synthetic oil or hydrocarbons distillates in a plastic recycle process using supercritical water as a reaction medium into a finished liquid hydrocarbon fuel by removing impurities such as i.e. silicon, chlorides, metals, heteroatoms, etc., in a pre-treatment zone and may be passed into a feed drum or a continuous mixed settler vessel. The feed is introduced into a hydrogen atmosphere reactor. The reactor effluent is passed to a separator for extracting product mixture by addition of make-up or recycled hydrogen to the separator. The overhead product mixture is water washed to remove sour water or salt. The separator effluent is passed to a distillation section for extracting a liquid fuel product stream. A portion of the hydro processing product stream may be recycled to the feed drum or the continuous mixed settler vessel, which reduces concentration of diolefins.