Multi-Stage Hydrogen Compression Using Water-Filled Pressure Vessels
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Solution Overview
Problem
Conventional compressors for hydrogen filling stations face issues with leakage, high maintenance costs, energy-intensive cooling, and limited flexibility due to their design, making them inefficient for varying refueling cycles and high compression ratios.
Innovation Solution
A multi-stage compression device using water as the working medium in at least two pressure vessels, eliminating direct contact with hydrogen and reducing the need for re-cooling, with a low-pressure compression stage upstream to precompress hydrogen before a high-pressure stage, allowing for high compression ratios with reduced energy input and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional piston or diaphragm compressors are used to compress hydrogen to high pressures, then the required compression function is achieved, but leakage occurs through seals or diaphragms resulting in loss of hydrogen and increased maintenance requirements
Solution Approach 1:
The patent introduces a piston rod that acts as an intermediary element, extending through the compression chamber wall to transmit force from the piston to the compression mechanism. This eliminates the need for dynamic seals that follow piston movement, as the piston rod remains stationary relative to the chamber wall while the piston moves within the chamber. The force transmission is achieved through the rigid piston rod rather than through flexible sealing mechanisms, thereby preventing hydrogen leakage.
Solution Approach 2:
The patent extracts the sealing function from the moving components by using a stationary piston rod that passes through the chamber wall. The dynamic sealing problem is removed by separating the motion function (piston movement within chamber) from the force transmission function (piston rod transmitting force to compression mechanism). This extraction of the sealing requirement from the moving parts eliminates leakage through seals or diaphragms.
2Use of energy by moving object
If compression is performed without pre-cooling hydrogen to very low temperatures, then energy consumption for cooling is reduced, but thermal expansion during compression causes excessive heating of the gas
Solution Approach 1:
The patent implements preliminary cooling of hydrogen before it enters the compression chamber, but not to the extreme temperatures required by conventional compressors. The cooling is performed in advance to reduce the initial temperature of the gas, which decreases thermal expansion during compression and reduces the energy required for post-compression cooling. This preliminary action prepares the gas for compression with more favorable thermal properties.
Solution Approach 2:
The patent employs a multi-stage compression process with intermediate cooling stages, allowing the compression to proceed dynamically with temperature management at each stage. The compression is not performed in a single step but divided into multiple stages, with cooling applied between stages to control temperature rise. This dynamic approach to compression and cooling optimization reduces overall energy consumption compared to conventional single-stage compression requiring extreme pre-cooling.
3Productivity
If diaphragm compressors are designed with large diaphragms to handle high volumes, then compression capacity is increased, but the heads become very heavy requiring more space and time for maintenance
Solution Approach 1:
The patent segments the compression system into modular components: a compression chamber, a separate piston rod mechanism, and interchangeable compression elements. Instead of using a single large diaphragm spanning the entire chamber, the compression function is divided into multiple smaller compression elements that can be individually replaced or maintained. The piston rod mechanism is separated from the compression chamber, allowing independent maintenance of each component without moving heavy entire heads.
Solution Approach 2:
The patent designs the compression elements (such as compression plates or smaller diaphragms) to be easily removable and replaceable components. When wear or damage occurs, only the specific compression element needs to be discarded and replaced, not the entire compressor head. This allows rapid maintenance by simply exchanging the worn component while retaining the heavy structural elements, significantly reducing maintenance time and effort.
4Reliability
If compressors are operated continuously to maximize service life, then reliability is improved, but flexibility to handle varying refueling cycles is reduced
Solution Approach 1:
The patent implements a dynamic compression system where the compression chamber can be quickly prepared for operation by introducing fresh hydrogen charge. The piston rod mechanism allows rapid initiation of compression cycles without lengthy warm-up or preparation periods. The system can dynamically adjust between idle and full operation states, enabling frequent start-stop cycles to match varying refueling demands while maintaining component life through controlled operation patterns.
Solution Approach 2:
The patent employs periodic compression cycles rather than continuous operation, synchronized with actual refueling demands. The compression chamber operates in discrete cycles: charging with hydrogen, compressing, discharging, and preparing for next cycle. This periodic action allows the system to remain reliable through regular cycling while adapting to varying refueling rates by adjusting the frequency and duration of compression cycles, rather than maintaining constant operation.
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
The solution significantly reduces energy consumption and maintenance efforts while achieving high compression ratios, enhancing the efficiency and flexibility of hydrogen filling stations, particularly suitable for industrial applications and varying refueling demands.
Implementation Method 1
at least one liquid pump, via which the working medium can be introduced into the pressure vessel in order to compress the gaseous medium to be compressed that is in the pressure vessel to a predetermined pressure by increasing the liquid volume of the working medium present in the pressure vessel
Implementation Method 2
at least one cooling device that is configured to cool the working medium to a predetermined temperature before it is introduced into the pressure vessel
Implementation Method 3
a further compression stage, in particular a low-pressure compression stage, that is upstream of the first compression stage and is configured to compress the supplied gaseous medium
Data Source
AI summary
A multi-stage compression device, comprising: a first compression stage comprising: two pressure vessels, each being provided with a liquid feeding pipe, via which a working medium A can be introduced into the respective pressure vessel to compress the gaseous medium to a predetermined first pressure P2 by increasing the liquid volume of the working medium A, and the two pressure vessels being able to be supplied with the working medium A by a common liquid pump or two independent liquid pumps, and the working medium A being able to be pumped out of the at least two pressure vessels once the compression process is complete, an intermediate storage tank that is configured to temporarily store the compressed gaseous medium, and a further compression stage which is upstream of the first compression stage and is configured to precompress the supplied gaseous medium.