Dividing Wall Column Ethylene Oxide Purification
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Solution Overview
Problem
The existing methods for refining crude ethylene oxide are costly and inefficient, requiring multiple distillation columns and steps, which leads to high equipment costs, safety concerns, and side reactions that reduce yield and increase maintenance, while also failing to effectively address impurity issues like acetaldehyde and ethylene glycol formation.
Innovation Solution
A method involving distillation in a dividing wall column that separates a purified ethylene oxide stream and an isolated acetaldehyde stream without the need for absorption or stripping, using a dividing wall column with specific staging and heating configurations to minimize residence time and side reactions, thereby reducing equipment needs and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple distillation columns and steps are used for refining crude ethylene oxide, then purification effectiveness is improved, but equipment costs and process complexity increase
Solution Approach 1:
The patent combines multiple distillation columns into a single integrated dividing wall column that performs water absorption, stripping, and reabsorption operations simultaneously. The dividing wall creates separate zones within one column structure, eliminating the need for multiple separate columns while maintaining purification effectiveness.
Solution Approach 2:
The dividing wall column performs multiple functions: it absorbs ethylene oxide in water, strips the absorbed EO, and reabsorbs it again, all within a single column structure. This multi-functional design replaces what would traditionally require separate dedicated columns for each operation.
2Manufacturing precision
If multiple distillation columns are used for refining crude ethylene oxide, then purification effectiveness is improved, but maintenance costs increase
Solution Approach 1:
By merging multiple column operations into a single dividing wall column structure, the patent reduces the total number of equipment components that require maintenance. Fewer columns mean fewer pumps, valves, and associated equipment, directly reducing maintenance costs and downtime.
3Productivity
If ethylene oxide and water are contacted at elevated temperatures for extended periods, then separation efficiency is improved, but side reactions increase
Solution Approach 1:
The patent rapidly processes the ethylene oxide-water mixture through the dividing wall column, minimizing the residence time at elevated temperatures. The distillation process is designed to achieve separation quickly, preventing the prolonged thermal contact that would otherwise lead to glycol formation and other side reactions.
Solution Approach 2:
The patent optimizes operating parameters including temperature, pressure, and flow rates to achieve efficient separation within minimal residence time. By carefully controlling these parameters, the process maintains high separation efficiency while limiting the time window for unwanted side reactions to occur.
4Productivity
If traditional absorption-stripping-reabsorption process is used, then ethylene oxide recovery is improved, but capital requirements increase
Solution Approach 1:
The patent integrates the absorption, stripping, and reabsorption operations into a single dividing wall column, eliminating the need for three separate columns that would be required by traditional process design. This integration dramatically reduces capital requirements while maintaining ethylene oxide recovery efficiency.
Solution Approach 2:
The dividing wall column serves as a multi-functional unit that performs all three operations (absorption, stripping, reabsorption) simultaneously, replacing what would traditionally require three separate dedicated columns. This universal design reduces equipment investment and simplifies the overall process architecture.
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 results in a highly purified ethylene oxide stream with reduced capital and energy costs, minimized side reactions, and a simplified refining process that eliminates the need for additional columns and steps, achieving high yield and purity while avoiding hazardous conditions.
Implementation Method 1
distilling the feed stream in a dividing wall column
Data Source
AI summary
The present invention provides simplified, efficient methods for refining a crude ethylene oxide (EO) containing mixture of water, EO, aldehydes and various gases comprising distilling the mixture in a dividing wall column having a receiving side and a product side and drawing each of a purified ethylene oxide stream and an isolated acetaldehyde stream from the product side of the dividing wall column, while minimizing the time during which a mixture containing more than 1 wt. % of each of ethylene oxide and water are in contact at a temperature above 80° C. to 2 minutes or less. No side draw is removed from the dividing wall column on its receiving side. The purification of the crude ethylene oxide needs no stripper or second absorber. The overhead and bottoms from the dividing wall column are recycled into the column or are reused in ethylene oxide production. The resulting purified EO stream may be more than 99.9% pure.