HF-HFC-254eb Azeotrope Distillation for Refrigerant Separation
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Solution Overview
Problem
The refrigeration industry faces challenges in finding alternatives to ozone-depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) with high global warming potential, necessitating the development of hydrofluoroolefins that have low ozone depletion and global warming potentials, which are difficult to separate due to their azeotropic properties.
Innovation Solution
The development of processes involving distillation steps to separate 1,1,1,2-tetrafluoropropane from mixtures with 1,1,1,2,3-pentafluoropropane and hydrogen fluoride, utilizing azeotropic and near-azeotropic compositions, and pressure swing distillation to achieve pure components, thereby overcoming the separation difficulties posed by their azeotropic behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hydrofluoroolefins are used as refrigerant alternatives, then ozone depletion potential is reduced, but separation difficulty increases due to azeotropic properties
Solution Approach 1:
The patent uses an azeotropic mixture of HFC-134a and HF as an intermediary substance to facilitate the separation of hydrofluoroolefins from the reaction mixture. This intermediary forms a constant-boiling mixture that can be distilled as a single unit, simplifying the separation process despite the azeotropic nature of the components
Solution Approach 2:
The patent employs pressure swing distillation, which involves changing the pressure parameter during the distillation process. By varying pressure, the azeotropic composition and boiling points change, allowing for the separation of components that would otherwise be difficult to separate due to their azeotropic properties
2Manufacturing precision
If distillation is used to separate azeotropic mixtures, then component purity is improved, but energy consumption increases
Solution Approach 1:
The patent performs preliminary separation steps before the main distillation process. The reaction mixture is first processed to concentrate the hydrofluoroolefins and azeotropic mixture, reducing the volume that needs to be processed in the energy-intensive distillation step
Solution Approach 2:
The separation process is divided into multiple stages: initial separation of the azeotropic mixture, followed by pressure swing distillation to separate the components. This segmentation allows each step to be optimized independently, reducing overall energy consumption while achieving high purity
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
These processes effectively separate 1,1,1,2-tetrafluoropropane and hydrogen fluoride, producing 1,1,1,2,3-pentafluoropropane essentially free of hydrogen fluoride, enabling the production of refrigerants with reduced environmental impact.
Implementation Method 1
processes for separating 1,1,1,2-tetrafluoropropane from a mixture comprising 1,1,1,2-tetrafluoropropane, 1,1,1,2,3-pentafluoropropane and hydrogen fluoride comprising subjecting said 1,1,1,2-tetrafluoropropane, 1,1,1,2,3-pentafluoropropane and hydrogen fluoride mixture to a distillation step
Implementation Method 2
forming a column distillate composition comprising an azeotropic or near-azeotropic composition of said 1,1,1,2-tetrafluoropropane and hydrogen fluoride
Implementation Method 3
subjecting said first distillate composition to a second distillation step conducted at a different pressure than the first distillation step in which the component enriched as a first bottoms composition in the first distillation is removed in a second distillate
Data Source
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AI summary
Described is a process for separating 1,1,1,2-tetrafluoropropane and hydrogen fluoride from a mixture comprising 1,1,1,2-tetrafluoropropane, 1,1,1,2,3-pentafluoropropane and hydrogen fluoride comprising: subjecting said 1,1,1,2-tetrafluoropropane, 1,1,1,2,3-pentafluoropropane and hydrogen fluoride mixture to a distillation step, forming a column distillate composition comprising an azeotropic or near-azeotropic composition of said 1,1,1,2-tetrafluoropropane and hydrogen fluoride, and a bottoms composition of 1,1,1,2,3-pentafluoropropane. The column distillate may optionally be made essentially free of 1,1,1,2,3-pentafluoropropane and the column bottoms composition may optionally be made essentially free of HF. Also described is a process for separating 1,1,1,2-tetrafluoropropane and hydrogen fluoride from a mixture of 1,1,1,2-tetrafluoropropane and hydrogen fluoride. Also described are azeotropic and azeotrope-like compositions comprising 1,1,1,2-tetrafluoropropane and hydrogen fluoride.