Process for separation and purification of renewable propane
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Solution Overview
Problem
Current methods for separating propane from hydrogen in gas streams generated from hydrotreatment of renewable feedstocks, such as glyceridic and glycerol-containing sources, are inefficient in terms of energy consumption and footprint, and do not maximize hydrogen recovery.
Innovation Solution
A method involving a membrane separation unit that is selective for hydrogen over propane, followed by elevated pressure distillation, which reduces the volume of gas to be separated and optimizes energy usage by first separating hydrogen from propane using the membrane and then further refining the retentate stream in the distillation unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional separation methods (cryogenic distillation or gas separation trains) are used to separate propane from hydrogen, then separation can be achieved, but energy consumption is high and footprint is large
Solution Approach 1:
The separation process is divided into two distinct stages: first, a membrane separation unit selectively permeates hydrogen from the gas stream, and second, an elevated pressure distillation unit further purifies the retentate stream. This segmentation allows each unit to perform a specialized function, reducing the overall energy requirement compared to using a single conventional separation system.
Solution Approach 2:
The membrane separation unit acts as an intermediary between the raw gas stream and the final separation achieved by distillation. By pre-concentrating propane in the retentate stream and removing most hydrogen through the membrane, the intermediary step reduces the burden on the subsequent distillation unit, thereby lowering total energy consumption.
2Area of stationary object
If conventional separation methods are used, then propane and hydrogen can be separated, but the footprint of the separation plant is large
Solution Approach 1:
The membrane separation unit utilizes thin-film membranes with selective permeability to separate hydrogen from propane. This technology occupies significantly less space than conventional cryogenic distillation columns or gas separation trains, while maintaining high separation efficiency and hydrogen recovery rates.
Solution Approach 2:
The process operates at elevated pressures, which enhances the selectivity and permeability of the membrane while also improving the efficiency of the subsequent distillation unit. By changing the pressure parameter, the system achieves effective separation in a more compact configuration compared to atmospheric pressure systems.
3Device complexity
If a single separation step is used, then the process is simpler, but hydrogen recovery is not maximized and separation is incomplete
Solution Approach 1:
The membrane separation unit performs a preliminary separation of hydrogen from the gas stream before the retentate enters the distillation unit. This preliminary action removes the bulk of hydrogen, allowing the subsequent distillation step to focus on achieving high-purity separation of the remaining components, thereby maximizing overall hydrogen recovery.
Solution Approach 2:
The two separation units operate in continuous series, with the output of the membrane unit feeding directly into the distillation unit. This continuous action ensures that hydrogen is progressively removed through both stages, maximizing recovery efficiency while maintaining a relatively simple overall process flow.
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 enables a two-fold separation of hydrogen from propane, reducing the energy consumption and footprint of the separation process while maximizing the recovery of both hydrogen and propane, particularly in the context of renewable fuels production.
Implementation Method 1
providing a membrane having a feed side and a permeate side, the membrane being selective for hydrogen over propane; passing the gas stream across the feed side of the membrane; withdrawing from the permeate side a permeate stream enriched in hydrogen and depleted in propane
Implementation Method 2
subjecting the retentate stream to elevated pressure distillation to separate hydrogen from propane
Implementation Method 3
elevated pressure distillation to separate hydrogen from propane; lower volume and higher dew point temperature of gas that has to be treated
Data Source
AI summary
A method for treating a gas stream comprising hydrogen and propane, where a combination of membrane separation and elevated pressure distillation is used to separate the hydrogen gas from the propane gas.