Polymer Effluent Fractionation With Matched Column Pressure
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Solution Overview
Problem
Conventional methods for recovering feedstock components from polymerization reaction effluents require high-pressure distillation columns, compressors, and refrigeration units, leading to increased capital and energy costs, as well as operational inefficiencies and process delays.
Innovation Solution
Operating a deethanizer column at a pressure similar to that of an upstream dehexanizer column, eliminating the need for a dehexanizer overhead compressor, and optimizing the separation process to reduce steam/energy consumption and minimize ethylene venting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the deethanizer column is operated at double the pressure of the dehexanizer column (conventional method), then the separation of ethylene and isobutane is improved, but the equipment complexity and energy consumption increase due to requiring a dehexanizer overhead compressor
Solution Approach 1:
The patent changes the pressure parameter of the deethanizer column from the conventional double pressure to operate at similar pressure to the dehexanizer column. This parameter change eliminates the need for a dehexanizer overhead compressor while maintaining effective separation through optimized side stream withdrawal and reflux ratio control
Solution Approach 2:
The patent extracts the isobutane component from the overhead stream via a side stream withdrawal located below the feed stage. This extraction approach allows selective removal of isobutane without requiring compression of the entire overhead stream, thereby eliminating the compressor while maintaining separation effectiveness
2Manufacturing precision
If the deethanizer column is operated at double the pressure of the dehexanizer column (conventional method), then the separation of ethylene and isobutane is improved, but the energy consumption increases due to steam and compressor requirements
Solution Approach 1:
The patent changes the pressure parameter to eliminate the compressor requirement, directly reducing energy consumption. The lower operating pressure reduces steam requirements for the reboiler while maintaining separation through optimized side stream withdrawal and reflux control
Solution Approach 2:
By extracting isobutane via side stream withdrawal rather than compressing the entire overhead stream, the patent eliminates compressor energy consumption while maintaining effective component separation through targeted extraction
3Manufacturing precision
If numerous distillation columns and compressors are used for feedstock purification (conventional method), then the purity of recovered components is improved, but the capital cost and equipment cost increase significantly
Solution Approach 1:
The patent combines the functions of multiple distillation columns and compressors into a simplified three-column fractionation train. The dehexanizer and deethanizer columns work together with a single overhead compressor serving the deethanizer, eliminating redundant equipment while maintaining purification effectiveness
Solution Approach 2:
The patent extracts valuable components (isobutane and olefins-free isobutane) via side stream withdrawals from the fractionation columns. This extraction approach allows direct recovery of pure components without requiring additional purification equipment, reducing capital costs while maintaining high purity
4Manufacturing precision
If conventional purification processes with multiple columns are used, then the recovery of high purity feedstock is improved, but the process time and operational efficiency decrease
Solution Approach 1:
The patent merges multiple purification steps into a single integrated three-column fractionation train operating in series. This consolidation reduces the number of separate operations, minimizes process delays, and improves operational efficiency while maintaining high purity recovery through continuous operation of the integrated system
Solution Approach 2:
The patent implements continuous operation of the fractionation train with continuous side stream withdrawals and recyclings. This continuous process eliminates batch processing delays and maintains steady-state operation, improving productivity while ensuring consistent high purity recovery of feedstock components
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 approach reduces capital costs, energy consumption, and operational difficulties while effectively separating and recycling valuable components, such as isobutane, from polymerization reactor effluents.
Implementation Method 1
separating a feed to a deethanizer column to produce a side stream comprising isobutane and ethylene and a bottoms stream comprising olefins-free isobutane
Implementation Method 2
utilizing a three-column fractionation train to separate and recycle isobutane and olefins-free isobutane
Data Source
AI summary
A method including recovering a polymerization reactor effluent stream from one or more polymerization reactors, flashing the polymerization reactor effluent stream to form a flash gas stream, separating, in a first column, the flash gas stream into a first column overhead stream, a first column side stream, and a first column bottoms stream, separating the first column overhead stream into a gas stream and a liquid stream, and introducing a feed comprising the gas stream and at least a portion of the liquid stream to a second column to produce a second column overhead stream, a second column side stream, and a second column bottoms stream. A second column bottoms stream flow rate can comprise less than or equal to about 25 vol % of a total flow rate and a second column side stream flow rate can comprise greater than or equal to about 75 vol % the total flow rate.