Propylene Recovery Condensing Unit With Adiabatic Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for recovering propylene from a gaseous stream containing propylene and light-boiling compounds are energetically inefficient and result in substantial propylene loss or require significant energy consumption, while also failing to effectively remove light-boiling compounds, which can disrupt the HPPO process and lead to impurities.
Innovation Solution
A process involving a condensing unit with spatially separated but thermally conductive zones, where a liquid cooling medium is cooled in multiple steps and expanded adiabatically to recover propylene, reducing light-boiling compounds through a series of heat exchanges, ensuring high purity and low energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If distillation is used to remove light-boiling compounds from propylene, then light-boiling compounds are removed, but substantial propylene loss occurs
Solution Approach 1:
The invention uses selective condensation based on phase transitions at different temperatures. The gaseous stream is cooled to condense propylene while light-boiling compounds remain gaseous and are removed. This avoids the propylene loss associated with distillation by utilizing temperature-dependent phase changes rather than vapor-liquid equilibrium separation.
Solution Approach 2:
The condensing unit is divided into multiple zones with progressively lower temperatures. The first zone condenses heavier components, the second zone condenses propylene, and the third zone removes remaining light-boiling compounds. This segmented approach allows selective recovery of propylene at each stage, maximizing recovery while removing impurities.
2Manufacturing precision
If purging is used to remove light-boiling compounds, then light-boiling compounds are removed, but substantial energy consumption is required
Solution Approach 1:
The invention implements continuous cooling and condensation throughout the process. The gaseous stream undergoes progressive cooling through multiple zones, continuously condensing and separating components. This continuous process is more energy-efficient than intermittent purging operations that require repeated heating and cooling cycles.
Solution Approach 2:
The invention converts the low condensation temperature requirement (which would normally demand excessive cooling energy) into a benefit by using the cold effluent stream from the absorption column as the cooling medium. This waste cold stream is reused to cool the gaseous stream, eliminating the need for external refrigeration energy input.
3Manufacturing precision
If absorption column is used for purification, then light-boiling compounds are removed, but energy consumption increases
Solution Approach 1:
The absorption column effluent stream, which is cold, serves its own purpose by providing the cooling medium for the condensing unit. The system uses its own waste cold stream to perform the cooling function, eliminating external energy requirements. This self-service approach makes the purification process energy-autonomous.
4Temperature
If multiple cooling steps are applied to liquid cooling medium, then cooling efficiency improves, but process complexity increases
Solution Approach 1:
The liquid cooling medium performs multiple functions: it is cooled in sequential steps, used as the cooling medium in the condensing unit, and then regenerated by the cold effluent stream. This multi-functional use of the same medium through sequential cooling steps achieves efficient temperature control without requiring separate systems 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
The process achieves high-purity propylene recovery with reduced light-boiling compounds, minimizing re-introduction of impurities and maintaining efficient energy use, suitable for recycling in the epoxidation process.
Implementation Method 1
cooling the liquid cooling medium stream in two or more cooling steps to a temperature T4, which is lower than the temperature T1
Implementation Method 2
expanding the liquid cooling medium stream, preferably adiabatically, within the second zone, thereby obtaining from the first zone an at least partially liquid stream comprising propylene
Implementation Method 3
first and second zone are spatially separated from each other but are thermally conductive coupled to each other
Data Source
AI summary
The present invention relates to a process for recovering propylene from a gaseous stream comprising propylene and a light-boiling compound, the light-boiling compound having a boiling point at 1013 mbar (abs.) below −50° C., in a condensing unit, wherein the condensing unit has a first zone, preferably being a condensing zone, and a second zone, preferably being an evaporation zone, wherein first and second zone are spatially separated from each other but are thermally conductive coupled to each other, the process comprising(i) providing a gaseous stream comprising propylene and a light-boiling compound;(ii) providing a liquid cooling medium stream having a temperature T1;(iii) cooling the liquid cooling medium stream in two or more cooling steps to a temperature T4, which is lower than the temperature T1, thereby obtaining a liquid cooling medium stream having temperature T4;(iv) feeding the gaseous stream comprising propylene and a light-boiling compound from (i) into the first zone of the condensing unit and feeding the liquid cooling medium stream having the temperature T4 obtained from (iii) to the second zone of the condensing unit;(v) expanding the liquid cooling medium stream, preferably adiabatically, within the second zone, thereby obtaining from the first zone an at least partially liquid stream comprising propylene, which is depleted in light-boiling compounds compared to the stream provided in (i).