Influence of airtightness in cylinder on air compressor
The volume of compressed gas measured at the outlet of the air compressor and converted to the air compressor in suction state in unit time is called the productivity of the air compressor.
The productivity of air compressor is smaller than the gas volume flowing into air compressor.
The ratio of these two volumes is called leakage coefficient, that is: λ = K / V, where k represents the productivity of air compressor, m3 / min; V represents the volume of gas flowing into the first stage cylinder every minute, m3.
There are two types of leakage: external and internal. The external leakage refers to the leakage of gas outside the scope of the cylinder working chamber (leakage into the atmosphere, leakage into the suction pipe); the internal leakage refers to the leakage into the cylinder working chamber (leakage through all valves except the 1st stage suction valve, leakage through the double acting cylinder piston, etc.).
The coefficient λ only considers the external leakage.
When the lift distance of the valve plate is very large (it will be slow when closing), the valve plate is not fully seated on the contact surface of the valve seat, and the valve plate spring is damaged, leakage will occur.
The leakage of stage 1 discharge valve is the external leakage only when it occurs from the beginning of expansion to the opening of suction valve.
After level 1, the leakage of Yang at all levels is internal, because they are leaked into the studio of the previous level. These losses will increase the pressure of the previous stage, but have no direct impact on the production filtration.
In addition to the leakage through the valve, the external leakage may also occur through the piston ring (within the time from the start of the stroke in the double acting cylinder to the opening of the gas valve).
The internal and external leakage of single acting cylinder may occur in the whole compression process, discharge process and expansion process.
The leakage through the packing box with metal ring is usually very small.
The laxity of all kinds of connectors (flange, safety valve, broken drain valve, etc.) is also the cause of external leakage. Finally, the consumption of air blowing on the cooler and on the condensation tank in front of the air distributor is also an external loss.
The loss of blowing is about 0.3% at each stage. The average value of leakage through the piston ring can be taken as 1-3% for each stage, and increases with the decrease of rated production rate. When the number of revolutions increases, the leakage through the piston ring decreases.