Two-Stage Condensation for Ethylene Purification with Minimal Loss
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Solution Overview
Problem
Current methods for producing ethylene from petroleum feedstocks are inefficient and costly, and the separation of light components from ethylene streams often results in ethylene loss, particularly when dealing with high proportions of oxygenates like acetaldehyde, which can cause fouling and catalyst poisoning.
Innovation Solution
A process involving a stripper (demethanizer) where the gaseous phase is condensed using a refrigerant stream initially cooled by liquid propane or propylene, followed by a secondary condensation using liquid ethane or ethylene to minimize ethylene loss and remove light components without the need for caustic washes or separate wash columns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a very low temperature is required to separate light components from ethylene stream, then separation efficiency is improved, but ethylene loss increases due to condensation of ethylene with light components
Solution Approach 1:
The condensation process is divided into two distinct stages: first condensing heavy components (CO2, H2O, oxygenates) at a first temperature, then condensing light components (H2, CH4, CO) at a lower second temperature. This segmentation allows selective condensation at different temperature levels, preventing ethylene loss while achieving complete separation of light components.
Solution Approach 2:
The invention changes the temperature parameter in two distinct steps during condensation. The first condensation occurs at a higher temperature (first temperature) to remove heavy components, and the second condensation occurs at a lower temperature (second temperature) to remove light components. This parameter change approach enables selective separation without condensing ethylene.
2Manufacturing precision
If caustic wash or wash column is used to remove oxygenates, then oxygenate removal is improved, but process complexity and cost increase
Solution Approach 1:
The invention merges the oxygenate removal function into the existing condensation process by controlling condensation temperatures and pressures. Instead of adding separate caustic wash or wash column units, the condensation step simultaneously achieves both light component removal and oxygenate removal through selective condensation, simplifying the overall process.
Solution Approach 2:
The condensation process itself performs the oxygenate removal function without requiring external chemical treatment units. By optimizing temperature and pressure parameters, the system uses the condensation mechanism to selectively separate oxygenates from the ethylene stream, making the process self-sufficient and eliminating the need for additional caustic wash equipment.
3Manufacturing precision
If conventional condensation is used to remove light components, then light component removal is improved, but ethylene loss occurs due to co-condensation
Solution Approach 1:
The condensation process is divided into two distinct stages: first condensing heavy components (CO2, H2O, oxygenates) at a first temperature, then condensing light components (H2, CH4, CO) at a lower second temperature. This segmentation allows selective condensation at different temperature levels, preventing ethylene loss while achieving complete separation of light components.
Solution Approach 2:
The invention changes the temperature parameter in two distinct steps during condensation. The first condensation occurs at a higher temperature (first temperature) to remove heavy components, and the second condensation occurs at a lower temperature (second temperature) to remove light components. This parameter change approach enables selective separation without condensing ethylene.
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 reduces ethylene loss and achieves high-purity ethylene production by optimizing condensation temperatures and using ethane or ethylene as cooling agents, allowing for the removal of light components and oxygenates, thereby improving the efficiency and cost-effectiveness of ethylene recovery.
Implementation Method 1
the gaseous phase on top of the stripper is condensed in a heat exchanger cooled by a refrigerant stream
Implementation Method 2
the refrigerant stream consists of one or more C3 or C4 hydrocarbons advantageously it consists of liquid and gaseous propane or propylene
Implementation Method 3
the first gaseous phase is condensed in a heat exchanger cooled by liquid ethane or liquid ethylene
Data Source
AI summary
A process for removing light components from an ethylene stream may include providing a dried ethylene stream containing ethylene, ethane, CO, CO2, H2, CH4, and C3+ hydrocarbons. The process may include sending the dried ethylene stream to a stripper to produce an overhead stream containing ethylene, CO, H2 and CH4, and a bottom stream containing ethylene, ethane, CO2, and C3+ hydrocarbons. The gaseous phase on top of the stripper may be condensed in a heat exchanger cooled by a refrigerant stream to get a first gaseous phase and a first liquid phase. The first gaseous phase may be condensed in a heat exchanger cooled by liquid ethane or liquid ethylene to get a second gaseous phase containing ethylene CO, H2 and CH4 and a second liquid phase. The first and second liquid phases may be the reflux of the stripper.