Alkylene Oxide Recovery Column Integration
Solution Overview
Problem
The recovery of alkylene oxide from dilute gaseous reaction effluents is inefficient and poses safety concerns due to the handling of concentrated ethylene oxide, which can lead to runaway polymerization and explosions, especially when separate distillation columns are used for stripping and reabsorption.
Innovation Solution
A single alkylene oxide recovery column is used, incorporating a stripping section to convert the feed stream to a gas phase, followed by partial condensation and reabsorption with a water stream to produce an aqueous solution, while stripping carbon dioxide and oxygen, thereby reducing equipment costs and safety risks by minimizing areas of concentrated ethylene oxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If separate distillation columns are used for stripping and reabsorption, then the recovery process can be carried out in distinct steps, but equipment costs increase and safety concerns arise due to areas of concentrated ethylene oxide
Solution Approach 1:
The patent combines the stripping column and reabsorption column into a single integrated column system. The stripping section and reabsorption section are positioned one above the other within the same column structure, sharing common infrastructure such as the column shell, tray systems, and support structures. This merging eliminates the need for separate standalone columns, reducing equipment costs while maintaining the functional separation needed for safe operation.
Solution Approach 2:
Within the single column, the system is segmented into distinct functional zones: a lower stripping section and an upper reabsorption section. Each section has its own operating conditions and chemical processes, with the stripping section operating at higher temperatures to vaporize ethylene oxide and the reabsorption section operating at lower temperatures to condense and absorb the vapor. This segmentation allows each zone to perform its specific function safely without creating concentrated ethylene oxide areas.
2Productivity
If separate distillation columns are used for stripping and reabsorption, then each step can be optimized independently, but the handling and transport of concentrated liquid ethylene oxide becomes necessary, creating safety risks
Solution Approach 1:
The patent introduces an intermediary vapor phase transport mechanism between the stripping and reabsorption sections. Instead of directly transporting concentrated liquid ethylene oxide from one column to another, the system uses vapor phase as an intermediate state. The ethylene oxide is vaporized in the stripping section, transported upward through the column as vapor, and then condensed and absorbed in the reabsorption section. This intermediary vapor phase eliminates the need for hazardous liquid transport.
Solution Approach 2:
The system utilizes phase transitions to safely handle ethylene oxide throughout the process. In the stripping section, liquid feed is heated and ethylene oxide transitions from liquid to vapor phase. The vapor then moves to the reabsorption section where it transitions back to liquid phase through condensation and absorption. These controlled phase transitions allow the system to process ethylene oxide without maintaining it in a concentrated liquid state during transport, thereby eliminating safety risks associated with liquid handling.
3Device complexity
If a single column is used for both stripping and reabsorption, then equipment costs are reduced and safety is improved, but the column design becomes more complex
Solution Approach 1:
The single column is designed with multi-functionality to perform both stripping and reabsorption operations. The column structure incorporates universal components such as standardized tray systems that can function in both vaporization and condensation zones, a unified shell that accommodates both hot and cold sections, and integrated support systems. This multi-functional design achieves cost savings while managing complexity through standardized, versatile components rather than requiring entirely separate specialized equipment for each function.
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 equipment costs and enhances safety by integrating stripping and reabsorption in a single column, minimizing the handling of concentrated ethylene oxide and improving the efficiency of alkylene oxide recovery.
Implementation Method 1
a stripping section in the alkylene oxide recovery column to convert a portion of a feed stream to a gas phase portion
Implementation Method 2
a condenser to partially condense the gas phase portion to produce an alkylene oxide rich vapor stream and a liquid reflux stream
Implementation Method 3
a reabsorption section above the stripping section that includes a water stream to reabsorb the alkylene oxide in the alkylene oxide rich vapor stream to produce an aqueous solution
Data Source
Figure 1
Figure 2
AI summary
Systems and processes for recovering alkylene oxide, including an alkylene oxide recovery column including a stripping section located in the column to convert a portion of a feed stream to a gas phase including alkylene oxide; a reabsorption section in the column above the stripping section including a water stream to reabsorb the alkylene oxide in the gas phase portion and to produce an aqueous solution, a first stripping gas to strip carbon dioxide and oxygen from the aqueous solution by converting a portion of the aqueous solution to a gaseous portion, producing an alkylene oxide stream, and a side take-off located at a bottom portion of the reabsorption section for removal of the alkylene oxide stream; a condenser to partially condense the gas phase portion; and a top take-off for removal of a light impurity fraction.