Propylene Oxide Distillation Reflux for Thermal Decomposition
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Solution Overview
Problem
The separation of propylene oxide and propene in industrial-scale processes is challenging due to their close boiling points, leading to thermal decomposition of propylene oxide and high energy consumption, especially when conventional distillation methods are used, which require high pressures that result in thermal decomposition.
Innovation Solution
A process involving the distillation of an effluent stream containing propylene oxide, water, organic solvent, and propene, where a condensed portion of the gaseous top stream enriched in propene is returned to the upper part of the distillation unit, allowing for efficient separation of propene from propylene oxide while avoiding decomposition and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional distillation is used to separate propylene oxide and propene, then separation is achieved, but thermal decomposition of propylene oxide occurs and energy consumption increases
Solution Approach 1:
The patent changes the operating parameters of the distillation process by operating at reduced pressure (vacuum conditions) and controlling temperature gradients. This allows separation of propylene oxide and propene at lower temperatures, preventing thermal decomposition while maintaining separation efficiency. The top of the distillation column operates at temperatures below 40°C and the bottom below 100°C under vacuum conditions.
Solution Approach 2:
The patent introduces an intermediary cooling system where the top stream is condensed and a portion is returned as reflux to the upper part of the distillation column. This reflux acts as a cooling mediator that prevents excessive temperature rise and thermal decomposition of propylene oxide during the separation process.
2Manufacturing precision
If conventional distillation is used to separate propylene oxide and propene, then separation is achieved, but energy consumption increases
Solution Approach 1:
By operating the distillation column under vacuum conditions, the patent reduces the boiling points of the components, allowing separation at lower temperatures. This parameter change significantly reduces the energy input required for heating and maintains efficient separation with lower energy consumption compared to conventional atmospheric pressure distillation.
Solution Approach 2:
The patent implements a continuous distillation process with a reflux system where condensed top stream is continuously returned to the column. This continuous operation with optimized reflux ratios maintains separation efficiency while minimizing energy waste, as the reflux liquid provides continuous cooling and mass transfer without requiring additional energy input for intermittent operations.
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 separates propene from propylene oxide, preventing thermal decomposition and lowering energy consumption, making it economically advantageous and efficient.
Implementation Method 1
separating propene from a reaction mixture resulting from the epoxidation
Implementation Method 2
a condensed portion of a gaseous top stream, which is enriched in propene, is returned
Data Source
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AI summary
The present invention is related to a process for preparing propylene oxide, comprising (i) providing a stream comprising propene, hydrogen peroxide or a source of hydrogen peroxide, water, and an organic solvent; (ii) passing the liquid feed stream provided in (i) into an epoxidation zone comprising an epoxidation catalyst comprising a titanium zeolite, and subjecting the liquid feed stream to epoxidation reaction conditions in the epoxidation zone, obtaining a reaction mixture comprising propene, propylene oxide, water, and the organic solvent; (iii) removing an effluent stream from the epoxidation zone, the effluent stream comprising propylene oxide, water, organic solvent, and propene; (iv) separating propene from the effluent stream by distillation, comprising (iv.1) subjecting the effluent stream to distillation conditions in a distillation unit, obtaining a gaseous top stream S0 enriched in propene compared to the effluent stream subjected to distillation conditions, and a liquid bottoms stream S01 enriched in propylene oxide, water and organic solvent compared to the effluent stream subjected to distillation conditions; (iv.2) returning a condensed portion of the stream S0 to an upper part of the distillation unit.