Ethylene Recovery via Absorption Solvent System
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Solution Overview
Problem
The production of polyethylene is hindered by high energy costs and capital expenditures due to the need for multiple distillation columns and cryogenic temperatures in purifying high-purity feedstocks, and conventional processes for recovering unreacted ethylene are energetically unfavorable and expensive.
Innovation Solution
A polyethylene production process that involves contacting ethylene with a polymerization catalyst, separating a light gas stream containing unreacted ethylene, and using an absorption solvent system comprising copper chloride, aniline, and N-methylpyrrolidone to absorb ethylene, thereby recovering it efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple distillation columns and cryogenic temperatures are used to purify feedstock, then high purity monomer feedstock is achieved, but energy costs and capital expenditures increase significantly
Solution Approach 1:
The patent extracts and removes unreacted ethylene from the polymerization off-gas stream using an absorption solvent system, separating it from other gases before recycling. This extraction approach eliminates the need for energy-intensive distillation columns and cryogenic purification, achieving high purity recovery without the associated energy costs and capital expenditures
Solution Approach 2:
The patent changes the physical-chemical parameters by using an absorption solvent system that selectively absorbs ethylene at specific temperature and pressure conditions. This parameter change enables ethylene recovery from off-gas at ambient or mild conditions rather than requiring cryogenic temperatures, thus reducing energy consumption while maintaining high purity
2Loss of substance
If conventional purification processes are used to recover unreacted monomers, then monomer recovery is achieved, but the process becomes energetically unfavorable and expensive
Solution Approach 1:
The patent introduces an absorption solvent system as an intermediary substance that selectively binds to unreacted ethylene in the off-gas stream. This intermediary enables easy separation and recovery of ethylene without requiring energy-intensive conventional purification processes, making the recovery operation energetically favorable and cost-effective
3Manufacturing precision
If multiple distillation columns are operated, then high purity feedstock is produced, but infrastructure complexity and capital cost increase
Solution Approach 1:
The patent replaces the complex infrastructure of multiple distillation columns with a single absorption step that extracts unreacted ethylene from off-gas. This simplifies the overall process infrastructure while maintaining high purity recovery, eliminating the need for redundant processing steps and reducing capital expenditures
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 process significantly reduces energy costs and capital expenditures by enhancing ethylene recovery, improving the overall efficiency of polyethylene production while minimizing waste gas emissions.
Implementation Method 1
contacting the light gas stream with an absorption solvent system, wherein at least a portion of the ethylene from the light gas stream is absorbed by the absorption solvent system
Implementation Method 2
yielding a composition comprising a complex of the absorption solvent system and unreacted ethylene
Data Source
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AI summary
A polyethylene production process, comprising contacting ethylene and a polymerization catalyst under suitable reaction conditions to yield a polymerization product stream, separating a light gas stream from the polymerization product stream, wherein the light gas stream comprises ethane and unreacted ethylene, contacting the light gas stream with an absorption solvent system, wherein at least a portion of the ethylene from the light gas stream is absorbed by the absorption solvent system, removing unabsorbed gases of the light gas stream from contact with the absorption solvent system to form a waste gas stream, and recovering ethylene from the absorption solvent system.