The working principle of a reciprocating Hydrogen Compressor is to compress and transport hydrogen gas by changing the volume of gas inside the cylinder through the reciprocating motion of the piston. The specific process is as follows:
Inhalation process: When the piston is driven by the motor and the connecting rod is pushed by the crankshaft, starting from the top dead center (or bottom dead center) of the cylinder and moving away from the cylinder head, the volume inside the cylinder gradually increases and the pressure decreases. When the pressure inside the cylinder is lower than the hydrogen pressure inside the suction pipe, the suction valve opens under the pressure difference, and hydrogen is sucked into the cylinder. Until the piston moves to the bottom dead center (or top dead center), the suction process ends and the cylinder is filled with low-pressure hydrogen gas.
Compression process: After the piston reaches the bottom dead center (or top dead center), it begins to move in the opposite direction, that is, towards the cylinder head. As the piston moves, the volume inside the cylinder gradually decreases, the hydrogen gas is compressed, and the pressure and temperature continue to rise. During this process, the suction valve is closed to prevent the hydrogen gas that has been sucked back into the suction pipeline. When the hydrogen pressure inside the cylinder rises slightly above the pressure inside the exhaust pipe, the compression process ends.
Exhaust process: After the compression process is completed, the high-pressure hydrogen gas in the cylinder pushes the exhaust valve open, and the hydrogen gas is discharged through the exhaust valve to the exhaust pipeline and transported to the place where high-pressure hydrogen gas is needed. Until the piston moves to the top dead center (or bottom dead center) again, the exhaust process ends. Then the piston begins a new round of suction, compression, and exhaust processes, repeating this cycle to achieve continuous compression and delivery of hydrogen gas.
The reciprocating hydrogen compressor mainly consists of the following structural components:
Compressed section
Cylinder: It is a place where hydrogen is compressed, usually made of high-strength alloy materials, with high pressure resistance and corrosion resistance.
Piston: It performs reciprocating motion inside the cylinder, compressing hydrogen gas by changing the volume inside the cylinder. Piston rings are usually installed on the piston to seal the gap between the piston and the cylinder wall, preventing hydrogen gas leakage.
Piston rod: connects the piston and the crosshead, transmitting the reciprocating motion of the piston to the crosshead.
Air valve: installed on the cylinder, used to control the entry and exit of hydrogen gas. The suction valve opens during the piston suction stroke, allowing hydrogen gas to enter the cylinder; The exhaust valve opens during the piston exhaust stroke, releasing compressed hydrogen gas from the cylinder.
Transmission part
Crankshaft: It is the power transmission component of the compressor, driven to rotate by the motor, and converted into reciprocating motion of the piston through the connecting rod.
Connecting rod: connects the crankshaft and the crosshead, converting the rotational motion of the crankshaft into the reciprocating motion of the crosshead, thereby driving the piston to move inside the cylinder.
Crosshead: It connects the piston rod and connecting rod to guide and transmit force, making the reciprocating motion of the piston smoother.
Body part
Crankcase: Used to support and accommodate transmission components such as crankshafts and connecting rods, while also storing lubricating oil to provide lubrication and cooling for transmission components.
Cylinder block: As the installation foundation of the cylinder, it is usually connected to the crankcase to form the overall framework of the compressor.
Middle body: located between the cylinder block and crankcase, used to install components such as crosshead slides, providing guidance and support for the movement of the crosshead.
Auxiliary section
Lubrication system: including oil tank, oil pump, oil filter, oil cooler, etc., providing lubricating oil for various moving parts of the compressor, reducing friction and wear, and ensuring the normal operation of the compressor.
Cooling system: generally composed of a cooler, cooling water circulation pipeline, etc., used to cool the heat generated during the compression process, prevent the compressor temperature from being too high, ensure the compression efficiency of hydrogen gas and the safe operation of equipment.
Sealing system: In addition to piston ring sealing, it also includes components such as packing boxes, which are used to seal the gap between the piston rod and the cylinder to prevent hydrogen gas leakage.
Control system: usually composed of sensors, instruments, control panels, programmable logic controllers (PLCs) or distributed control systems (DCS), etc., used to monitor and control the operating parameters of the compressor, such as pressure, temperature, flow rate, etc., to ensure that the compressor operates in a safe and efficient state.
Inlet filter: installed at the inlet of the compressor, used to filter impurities and dust in hydrogen gas, protecting internal components of the compressor from wear and damage.
Buffer: Installed at the inlet and outlet of the compressor, it is used to reduce gas pressure fluctuations and protect the compressor and piping system from impact and vibration.
What roles do each component play in the hydrogen compression process?
1. Compression section
Cylinder:
As a space container for hydrogen compression, it provides a place for hydrogen compression. The volume change of its internal space directly determines the degree of compression of hydrogen gas. For example, during the movement of the piston, the hydrogen gas inside the cylinder is confined to a relatively closed space. As the piston advances, this space gradually shrinks, and the distance between hydrogen molecules decreases, thereby achieving the compression of hydrogen gas.
The cylinder wall needs to withstand the pressure of hydrogen gas, so the strength and corrosion resistance of its material are crucial for the safe and stable operation of the compressor. In high-pressure hydrogen environments, good materials can prevent cylinder rupture or hydrogen leakage.
Piston:
It is the key executor of hydrogen compression. The reciprocating motion of the piston inside the cylinder directly changes the volume of hydrogen gas inside the cylinder. When the piston moves towards the bottom of the cylinder, it squeezes hydrogen gas, reducing its volume and increasing its pressure, thereby achieving compression function.
The piston ring on the piston plays a sealing role, preventing hydrogen gas from leaking from the gap between the piston and the cylinder wall. The piston ring is tightly attached to the cylinder wall, forming a sealed barrier to ensure that hydrogen can only flow along the set path (through the valve) during the compression process, maintaining the effectiveness of the compression process. If the piston ring seal is not good and hydrogen gas leaks, it will not only reduce compression efficiency, but may also cause the compressor to fail to reach the required pressure.
piston rod:
It is a bridge connecting the piston and the crosshead, transmitting the reciprocating motion of the piston to the crosshead. In this process, it needs to withstand the reciprocating force of the piston to ensure stable transmission of force. For example, when the piston is subjected to the reaction force of hydrogen gas in the cylinder, the piston rod can transmit this force to the crosshead, making the entire transmission system work in coordination.
valve:
The suction valve and exhaust valve respectively control the suction and discharge of hydrogen gas. During the intake process, when the pressure inside the cylinder is lower than the pressure in the intake pipe, the intake valve opens, allowing hydrogen gas to enter the cylinder smoothly; During the exhaust process, when the hydrogen pressure in the cylinder is higher than the pressure in the exhaust pipe, the exhaust valve opens to allow the compressed hydrogen to be discharged. The timing of opening and closing the gas valve and good sealing are crucial for the normal compression and transportation of hydrogen gas. If the air valve is not opened and closed in a timely manner or sealed tightly, it will cause hydrogen reflux and leakage, affecting the efficiency and output pressure of the compressor.
2. Transmission part
Crankshaft:
As a power input component, it receives the rotational power of the motor and converts it into the reciprocating motion of the connecting rod. The rotation angle and speed of the crankshaft determine the frequency and stroke of the piston, thereby controlling the compression frequency and degree of hydrogen gas. For example, by adjusting the speed of the crankshaft, the operating frequency of the compressor can be changed, thereby adjusting the compression amount and output flow rate of hydrogen gas.
Connecting rod:
Connect the crankshaft and crosshead, and convert the rotational motion of the crankshaft into the reciprocating motion of the crosshead. It bears complex alternating loads during its movement and requires sufficient strength and stiffness to ensure the accuracy of force transmission. The length and structural design of the connecting rod also affect the stroke of the piston, which in turn affects the volume change of the cylinder and the compression ratio of hydrogen gas.
Cross head:
Plays the role of connecting the piston rod and connecting rod, while providing guidance for the reciprocating motion of the piston rod. It ensures that the piston can move back and forth in a straight line inside the cylinder, avoiding uneven force on the piston and cylinder wall that may cause eccentric wear or jamming. The good guiding performance of the crosshead helps to improve the stability and reliability of piston movement, ensuring the smooth progress of hydrogen compression process.
3. Body part
Crankcase:
Provide support and accommodation space for transmission components such as crankshafts and connecting rods. It protects the internal transmission components from external environmental interference and stores lubricating oil, allowing the transmission components to operate in a well lubricated environment. The lubricating oil inside the crankcase can reduce friction and wear between components, and take away some heat through the flow of oil, playing a cooling role.
Cylinder block:
As the installation foundation of the cylinder, ensure the stability of the cylinder during operation. It is connected to the crankcase, forming an integral structural framework that bears the pressure of hydrogen gas during compression and the reaction force generated by piston movement. The structural design and material selection of the cylinder block directly affect the overall strength and stability of the compressor.
Middle body:
Install components such as crosshead slides between the cylinder block and crankcase. It provides guidance and support for the movement of the crosshead, ensuring that it can reciprocate in the correct direction. The structure and accuracy of the middle body have a significant impact on the linear motion of the piston within the cylinder and the overall operational stability of the compressor.
4. Auxiliary section
Lubrication system:
Provide lubrication for various moving parts of the compressor to reduce friction and wear. For example, in the contact areas between the crankshaft and bearings, connecting rods and crankshafts, pistons and cylinder walls, etc., lubricating oil can form a layer of oil film, causing liquid friction between the relative moving parts, greatly reducing friction, reducing component wear, and extending the service life of the equipment.
Lubricating oil can also take away some heat during the circulation process, playing a cooling role. Heat is dissipated to the outside through equipment such as oil coolers to prevent damage to the compressor due to high temperatures.
Cooling system:
The heat generated during the cooling and compression process. During the hydrogen compression process, the internal energy of the gas increases and the temperature rises. The cooling system uses equipment such as coolers, such as water cooling or air cooling, to cool the high-temperature hydrogen gas, making the compression process closer to isothermal compression and improving compression efficiency. At the same time, the cooling system also cools the body, cylinders, and other components to prevent equipment from malfunctioning due to overheating.
Sealing system:
In addition to the piston ring seal, sealing components such as packing boxes are used to seal the gap between the piston rod and the cylinder, preventing hydrogen gas leakage. A good sealing system can ensure the hydrogen pressure inside the compressor, avoiding hydrogen leakage to the outside, causing energy waste and safety hazards.
Control system:
Monitor and control the operating parameters of the compressor, such as pressure, temperature, flow rate, etc. Real time data collection through sensors, such as installing pressure sensors at the intake and exhaust ports, temperature sensors at critical locations, and flow sensors in pipelines. The control system ensures the safe and efficient operation of the compressor by adjusting the motor speed, valve opening and closing time, and other methods based on these data. For example, when the exhaust pressure is too high or the temperature is abnormal, the control system can take timely measures such as alarm, shutdown, etc. to protect the compressor equipment.
Air intake filter:
Filter impurities and dust from hydrogen gas. Before hydrogen enters the compressor, the intake filter can remove solid particles, oil stains, and other impurities, preventing them from entering the interior of the compressor and avoiding wear, blockage, or corrosion of components such as valves, pistons, and cylinder walls, thereby ensuring the normal operation and service life of the compressor.
Buffer:
Installed at the inlet and outlet of the compressor to reduce gas pressure fluctuations. During the intake and exhaust process of the compressor, the flow of gas generates pressure fluctuations, and the buffer can smooth these fluctuations, making the intake and exhaust process of the compressor smoother. This helps to protect the components of the compressor such as the air valve and pipeline system, reduce damage caused by pressure shock and vibration, and also helps to improve the stability and reliability of the entire system.
