Reciprocating compressor refers to a compressor that periodically changes the volume of the cylinder through the reciprocating movement of the piston or diaphragm in the cylinder and realizes the pressurization and delivery of gas. According to the reciprocating components, it is divided into piston type and diaphragm type compressors.
When the reciprocating compressor works, the crankshaft drives the connecting rod, the connecting rod drives the piston, and the piston moves up and down. The movement of the piston changes the volume in the cylinder. When the piston moves down, the cylinder volume increases, the intake valve opens, the exhaust valve closes, and air is sucked in to complete the intake process; when the piston moves upward, the cylinder volume decreases, the outlet valve opens and the inlet valve closes to complete the compression process. Usually there is a piston ring on the piston to seal the gap between the cylinder and the piston, and there is lubricating oil in the cylinder to lubricate the piston ring.
Due to the complexity of the structure of the reciprocating compressor, there are many parts that may fail, and the reasons for the failure are different. The characteristic parameter signals of reciprocating compressors mainly include thermal signals, vibration signals, and noise signals, among which thermal signals include temperature of various components, displacement, exhaust pressure and pressure in the cylinder. Through the monitoring and analysis of characteristic signals, identifying and judging the type of compressor fault is the core idea of fault diagnosis technology that reciprocating natural gas compressor manufacturers should pay attention to.
Reciprocating compressor is a type of positive displacement compressor. Its main components include cylinder, crank and connecting rod mechanism, piston assembly, packing (that is, compressor seal), air valve, body and foundation, pipeline and accessories Equipment, etc.
The cylinder is one of the main parts of the reciprocating compressor. It should have a good surface to facilitate lubrication and wear resistance, and also have good thermal conductivity so that the heat generated by friction can be dissipated at the fastest speed; Enough air flow channel area and air valve installation area, so that the volume of the valve cavity can reach the pressure pulsation amplitude that can reduce the air flow, so as to ensure the normal operation of the air valve and reduce power consumption. The clearance volume should be smaller to improve the efficiency of the reciprocating compressor.
2. Crank and connecting rod mechanism
The mechanism includes crosshead, connecting rod, crankshaft, slide and so on. It is the main running and transmission component, which converts the circular motion of the motor into the reciprocating motion of the piston through the connecting rod. At the same time, it is also the main force-bearing component.
3. Piston assembly
There are mainly piston heads, piston rings, supporting shoes and piston rods. The shape and size of the piston are closely related to the cylinder, and are divided into double-acting and single-acting pistons. The piston ring is used to seal the high-pressure gas in the cylinder to prevent it from leaking from the gap between the piston and the cylinder. As the name suggests, the supporting shoe plays the role of supporting the piston, so the supporting shoe is also a vulnerable part, and the quality of the supporting shoe directly affects the service life of the reciprocating compressor.
Piston rod packing is mainly used to seal the gap between the inner seat of the cylinder and the piston rod to prevent gas from leaking in the radial direction of the piston rod. The manufacture and installation of the packing ring involves "three gaps". They are axial clearance (to ensure that the packing ring can float freely in the ring groove), radial clearance (to prevent deformation or damage of the packing ring due to the sinking of the piston rod) and tangential clearance (to compensate for the packing ring Wear). At present, the plane packing is mostly "three six petals" and "tangential incision three petals".
5. Air valve
The air valve is the most important component of a reciprocating compressor, and it is also the most easily damaged part. The quality of its design will directly affect the compressor's displacement, power consumption and operational reliability. A good air valve should have the following characteristics: high efficiency and energy saving (accounting for 3% to 7% of shaft power), perfect combination of air tightness and timeliness of action, long life (generally 8000h in actual life), small clearance volume, low noise and temperature rise, can be refurbished and used. At present, the material of the air valve is divided into metal and non-metal. As far as the current situation is concerned, the application of non-metal material valve discs is more and more extensive.
6. Piping and auxiliary equipment
Whether the reciprocating compressor's pipeline and the design of the input and output buffers are reasonable will directly affect the vibration of the unit.
Aipu is one of the leading reciprocating natural gas compressor manufacturers in China that can offer various types of compressors used in oil and gas industry. Contact us to know more and get an attractive price.
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