Compression and separation device and compression process
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Solution Overview
Problem
The compression of low molecular weight gases like hydrogen using volumetric compressors is inefficient for large volume flow rates, requiring multiple compressors in parallel due to limited volume capacity, while dynamic compressors are better suited but incur high energy losses with multiple stages and adding ballast gases increases power consumption.
Innovation Solution
A dynamic compressor system with multiple stages and intermediate refrigeration, where a low molecular weight gas is mixed with a high molecular weight gas to form a gas with a molecular weight greater than 10 g/mol, partially condensed, and then compressed in stages, with recovered condensates recycled to minimize energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If volumetric compressors are used to compress hydrogen, then compression is achievable, but multiple compressors in parallel are required for large volume flow rates due to limited volume capacity
Solution Approach 1:
The invention changes the molecular weight parameter of the gas being compressed by mixing hydrogen with a heavier gas (molecular weight >50 g/mol). This allows using a dynamic compressor with much larger volume capacity, eliminating the need for multiple parallel compressors while handling large hydrogen flow rates.
Solution Approach 2:
A heavier gas acts as an intermediary substance that temporarily increases the molecular weight of the mixture during compression. This intermediary gas enables the dynamic compressor to efficiently compress the mixture, after which the heavy gas is separated and recycled, leaving pure hydrogen.
2Productivity
If dynamic compressors are used to compress hydrogen, then large volume capacity is achieved, but multiple compression stages in series are required to achieve high pressure ratio
Solution Approach 1:
By changing the molecular weight parameter of the gas mixture (increasing it through mixing with heavy gas), the compression characteristics improve, allowing a single-stage dynamic compressor to achieve high pressure ratios that would otherwise require multiple stages.
3Productivity
If ballast gas is added to increase molecular mass of hydrogen, then compression efficiency improves, but power consumption increases significantly
Solution Approach 1:
The heavy ballast gas is not discarded after compression but is recovered through phase separation and recycled back to the mixing stage. This recovery and reuse of the heavy gas eliminates the continuous energy penalty that would otherwise result from compressing and discarding ballast gas with each batch.
Solution Approach 2:
The invention utilizes phase transition (condensation) of the heavy gas at intermediate temperatures during compression stages. This allows the heavy gas to be separated from hydrogen through phase separation, enabling its recovery and recycling without requiring additional compression energy.
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 significantly reduces energy loss compared to traditional methods, allowing efficient compression of hydrogen from 6 to 25 bars in fewer stages with minimal energy penalty, as demonstrated by the example of using CH2Cl2, reducing energy overhead from 150% to 26% compared to mixing with CO2.
Implementation Method 1
a first heat exchanger for cooling the third gas downstream of the first compression stage in order to partially condense it
Implementation Method 2
a first phase separator, means for sending the partially condensed third gas at the first phase separator to form a fourth gas having a lower molecular weight than the third gas and a condensed first liquid having a higher molecular weight than the third gas
Data Source
Figure 1
Figure 2
AI summary
In a compression process in a dynamic compressor having at least two compression stages (C2,C3), a first gas (1) having a first molecular weight of less than 10 g/mol is compressed, at least one second fluid (21) having a second molecular weight of greater than 50 g/mol is mixed with the first gas to form a third gas to be compressed (3) having a molecular weight of greater than 10 g/mol, the third gas is sent to the first compression stage (C2), the third gas is cooled in a first heat exchanger (R1) downstream of the first compression stage where it is partially condensed, the partially condensed third gas is sent to a first phase separator (P1) to form a fourth gas having a molecular weight lower than that of the third gas (9) and a first condensed liquid (11) having a molecular weight greater than that of the third gas, the fourth gas is sent from the first phase separator to the second compression stage (C3), the fourth gas compressed in the second compression stage is sent to be cooled in a second heat exchanger (R2) where it is partially condensed, the partially condensed fourth gas is sent to a second phase separator (P2) to produce a fifth gas (13) having a molecular weight lower than that of the fourth gas.