The principle of hydrogen compression is mainly based on the basic physical principle of gas compression, which is to increase the pressure and density of gas by reducing its volume. The following are several main principles of hydrogen compression and their corresponding compressor types:
1. Principle of Volumetric Compression
Piston compressor:
Working principle: The piston performs reciprocating motion inside the cylinder, and compresses the gas by changing the working volume inside the cylinder. During the inhalation process, the piston moves backwards, creating a low-pressure area inside the cylinder where hydrogen gas is drawn into the cylinder; During the compression process, the piston moves forward to compress the hydrogen gas inside the cylinder, increasing its pressure, and then discharging the high-pressure hydrogen gas through the exhaust valve.
Features: Mature technology, high reliability, wide applicability, capable of achieving high pressure ratio hydrogen compression. But it has a large volume, occupies a large area, and generates significant vibration and noise due to piston movement.
Diaphragm compressor:
Working principle: Compressing and transporting gas by reciprocating the diaphragm in the cylinder. The diaphragm is clamped by two restriction plates along the periphery and forms a cylinder. The diaphragm is driven back and forth in the cylinder by mechanical or hydraulic means. The cylinder is divided into two parts: the air chamber and the oil chamber. The diaphragm is driven by hydraulic oil to compress the hydrogen gas in the air chamber, thereby achieving the compression and transportation of hydrogen gas.
Characteristic: During the compression process, the gas is completely isolated from the lubricating oil, ensuring the purity of hydrogen gas. Good sealing performance, high compression ratio, capable of achieving high-pressure hydrogen compression. Smooth operation, minimal vibration, and low noise. However, the diaphragm is a critical component with a limited lifespan and requires regular replacement, resulting in higher costs. The displacement is relatively small and not suitable for high flow hydrogen compression.
Liquid ring compressor:
Working principle: The impeller of the liquid ring compressor is eccentrically installed inside the cylindrical pump casing. When the impeller rotates, the working fluid forms a liquid ring under the action of centrifugal force, and the space between the liquid ring and the impeller hub is divided into multiple chambers. As the impeller rotates, the volume of these chambers constantly changes, thereby achieving gas suction, compression, and discharge. For hydrogen compression, hydrogen is drawn into the chamber formed by the liquid ring and impeller, compressed and discharged under the rotation of the liquid ring.
Features: Relatively simple structure, smooth operation, low vibration and noise. Capable of handling gases containing certain impurities and moisture, with relatively low purity requirements for hydrogen gas. Suitable for hydrogen compression in the medium pressure range. But the efficiency is relatively low, especially under high pressure ratio conditions. Regular replacement of working fluids is required, resulting in high maintenance costs. The exhaust pressure is limited and not suitable for high-pressure hydrogen compression.
2. Principle of speed compression
Centrifugal compressor:
Working principle: By using a high-speed rotating impeller to do work on the gas, centrifugal force is generated, thereby increasing the pressure and velocity of the gas. After entering the impeller of the centrifugal compressor, hydrogen gas is accelerated and thrown out under the rotation of the impeller, and then enters the diffuser. In the diffuser, the velocity of the gas decreases, the pressure increases, and finally discharged from the compressor.
Features: High flow rate, suitable for large-scale hydrogen compression and transportation. But there are certain requirements for the molecular weight and density of the gas, and the start-up and operation are relatively complex, with high equipment costs.
3. Other compression principles
In addition to the two main compression principles mentioned above, there are also other types of Hydrogen Compressors, such as metal hydride hydrogen compressors, electrochemical hydrogen compressors, etc. These compressors adopt different working principles and technologies, suitable for specific application scenarios and requirements.
In summary, the principle of hydrogen compression is mainly based on two basic principles: volumetric compression and velocity compression. Different types of hydrogen compressors have their own unique features in terms of structure, working principle, performance characteristics, and applicable scenarios. When choosing a hydrogen compressor, it is necessary to comprehensively consider the specific application requirements and conditions to select the most suitable compressor type.
