Separating HCFC-1233 from HF via Liquid-Liquid Phase Split
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Solution Overview
Problem
The challenge lies in effectively separating monochloro-trifluoropropenes, such as 1,1,1-trifluoro-3-chloro-2-propene (HCFC-1233zd), from azeotropic or near azeotropic streams containing hydrogen fluoride (HF) due to their similar boiling points, which complicates purification and isolation in existing methods.
Innovation Solution
A method utilizing chilled, liquid phase separation combined with azeotropic distillation is employed, where the azeotropic or near azeotropic mixture is first cooled to separate into distinct phases, with the HF-rich phase being processed in a first azeotropic distillation column to remove pure HF, and the 1233zd-rich phase undergoing further distillation to isolate pure 1233zd, utilizing a series of distillation columns to achieve separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If azeotropic distillation is used to separate 1233zd from HF, then separation can be achieved, but the process becomes complex and requires multiple distillation columns
Solution Approach 1:
The patent applies preliminary action by performing liquid phase separation at low temperature before distillation. The azeotropic mixture is cooled to form two liquid phases, with HF preferentially dissolving in one phase and 1233zd in the other. This preliminary separation step reduces the load on subsequent distillation columns, allowing for simpler equipment design while achieving the required purity of 1233zd.
2Manufacturing precision
If conventional distillation is used to separate 1233zd from HF, then separation is attempted, but it is ineffective due to similar boiling points forming azeotropes
Solution Approach 1:
The patent applies parameter changes by utilizing temperature as a control parameter. The azeotropic mixture is cooled to a low temperature (below the azeotropic point) to induce liquid-liquid phase separation. This temperature change alters the distribution of components between phases, enabling effective separation of HF and 1233zd despite their similar boiling points, thus simplifying the overall manufacturing process.
Solution Approach 2:
The patent applies phase transitions by exploiting the liquid-liquid phase separation of the azeotropic mixture at low temperatures. The mixture transitions from a single liquid phase to two immiscible liquid phases, with HF concentrating in one phase and 1233zd in the other. This phase transition provides a simple and effective separation mechanism that avoids the complexity of multiple distillation steps.
3Productivity
If liquid phase separation is used to separate HF and 1233zd, then separation efficiency improves, but additional cooling equipment and process steps are required
Solution Approach 1:
The patent applies merging by combining the cooling and separation operations into a single integrated unit operation. The low-temperature liquid phase separation vessel serves both as the cooling chamber and the separation chamber. The azeotropic mixture is cooled and separated in one piece of equipment, eliminating the need for separate cooling and separation units, thus reducing overall device complexity while maintaining high separation efficiency.
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 allows for the efficient isolation of pure 1233zd from azeotropic or near azeotropic combinations with HF, overcoming the boiling point similarity issue and achieving high purity of both HF and 1233zd, thereby addressing the need for environmentally sustainable refrigerants with low global warming potential.
Implementation Method 1
cooling the effluent from the rectification column to a temperature sufficient to provide liquid phase separation into an HF rich phase and a 1233zd rich phase
Implementation Method 2
treating a mixture rich in HF relative to the azeotrope of 1233zd and HF in a distillation (rectification) column to obtain a distillate containing the azeotrope and a bottoms product of relatively pure HF
Data Source
AI summary
The invention relates to a process for separating monochloro-trifluoropropenes such as HCFC-1233 from azeotrope or azeotrope like combinations with HF. The process employs a cold, liquid phase separations and multiple azeotropic distillation trains.