Ethylene Oxygenate Removal via C2 Splitter and CO2 Adsorption
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Solution Overview
Problem
Existing methods for removing oxygenated contaminants from ethylene streams often result in caustic scrubber fouling due to reactive oxygenates, leading to reduced unit run length and significant disposal issues with red oil polymers.
Innovation Solution
A process that involves providing a dried ethylene stream, sending it to a C2 splitter/deethanizer to separate ethane and oxygenates, followed by a fixed bed CO2 adsorption zone to remove CO2, and then a demethanizer/CO stripper to recover hydrogen, methane, and carbon monoxide, eliminating the need for a caustic wash and wash column.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If caustic wash is used to remove oxygenated contaminants from ethylene stream, then oxygenate removal efficiency is improved, but caustic scrubber fouling occurs leading to reduced unit run length
Solution Approach 1:
The invention extracts and removes oxygenated contaminants (acetaldehyde, CO2, water) from the ethylene stream using a series of separation units (C2 splitter/deethanizer, fixed bed CO2 adsorption zone, demethanizer/CO stripper) before the ethylene enters the polymerization reactor. This prevents the oxygenates from reaching and fouling the caustic scrubber, thereby maintaining both high removal efficiency and extended unit run length.
Solution Approach 2:
The process performs preliminary removal of oxygenated contaminants through distillation and adsorption steps before the ethylene stream requires caustic washing. By removing acetaldehyde, CO2, and water in advance through the C2 splitter and CO2 adsorption zone, the subsequent caustic scrubber operates with minimal fouling risk, thus extending unit run length while maintaining removal efficiency.
2Manufacturing precision
If caustic wash is used to remove oxygenated contaminants, then oxygenate removal efficiency is improved, but significant disposal issues with red oil polymers occur
Solution Approach 1:
The invention extracts oxygenated contaminants (acetaldehyde, CO2, water) from the ethylene stream using dedicated separation units (C2 splitter/deethanizer, fixed bed CO2 adsorption zone, demethanizer/CO stripper) before polymerization. This prevents the formation of red oil polymers in the caustic scrubber, eliminating the disposal burden while maintaining effective oxygenate removal.
Solution Approach 2:
The process converts the potentially harmful interaction between oxygenates and caustic (which produces troublesome red oil polymers) into a beneficial separation process. By removing oxygenates through distillation and adsorption before they can react with caustic, the caustic scrubber operates cleanly without generating disposal problems, thus converting a harmful side reaction into a clean separation process.
3Manufacturing precision
If traditional separation methods are used to remove oxygenates, then oxygenate removal is achieved, but process complexity increases with multiple wash columns
Solution Approach 1:
The invention merges the removal of multiple oxygenated contaminants (acetaldehyde, CO2, water) into a integrated separation sequence using a C2 splitter/deethanizer followed by a fixed bed CO2 adsorption zone and demethanizer/CO stripper. This combined approach achieves comprehensive oxygenate removal more efficiently than multiple separate wash columns, reducing overall process complexity while maintaining high removal effectiveness.
Solution Approach 2:
The process replaces mechanical wash columns with chemical adsorption (fixed bed CO2 adsorption zone) and distillation-based separation (C2 splitter/deethanizer, demethanizer/CO stripper). This substitution eliminates the need for caustic chemicals and multiple wash columns, achieving oxygenate removal through physical and chemical separation mechanisms that are simpler to operate and maintain.
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 effectively removes oxygenated contaminants without caustic washes or wash columns, reducing fouling and disposal concerns, and produces high-quality ethylene suitable for further processing into various chemical products.
Implementation Method 1
sending said overhead to a fixed bed CO2 adsorption zone to recover a stream essentially free of CO2
Implementation Method 2
sending it to a C2 splitter/deethanizer to separate ethane and oxygenates
Implementation Method 3
sending said stream essentially free of CO2 to a demethanizer/CO stripper to recover an overhead comprising H2, CH4 and CO
Data Source
AI summary
The present invention is a process for removing oxygenated contaminants from an ethylene stream comprising:a) providing a dried ethylene stream (A) comprising essentially ethylene, up to 1 w % oxygenates, ethane, CO, CO2, H2, CH4 and C3+ hydrocarbons,b) sending said stream (A) to a C2 splitter/deethanizer to producea bottom stream comprising essentially ethane, oxygenates and C3+ hydrocarbons,an overhead comprising the remaining components,c) sending said overhead to a fixed bed CO2 adsorption zone to recover a stream essentially free of CO2,d) sending said stream essentially free of CO2 to a demethanizer/CO stripper to recover an overhead comprising H2, CH4 and CO, liquid ethylene at the bottoms.In another embodiment the CO2 removal step can be made on the recovered ethylene.