Nine common compressor parameters

1. Exhaust volume (i.e. volume flow)

Under the rated exhaust pressure, the volume of gas discharged by the air compressor in unit time is converted to the volume of gas in the intake state, which is the exhaust volume of the air compressor (i.e. volume flow), unit: m3 / min. Generally speaking, the exhaust volume of air compressor refers to how much cubic air is sucked in by the air inlet of the machine per minute, rather than how much cubic compressed air can be discharged from the air outlet of the machine per minute.

2. Exhaust pressure

Air compressor discharge pressure refers to the gas pressure (gauge pressure) finally discharged from the compressor, unit: MPa. In the air compressor industry, "kg" is commonly used as the pressure unit, 1kg = 0.1MPa. The discharge pressure marked on the famous brand of air compressor is called rated discharge pressure, which is also the maximum allowable discharge gauge pressure of the compressor. Exhaust volume and exhaust pressure are two very important parameters of air compressor.

3. Air compressor discharge temperature

Air compressor exhaust temperature refers to the temperature of the exhaust gas from the exhaust port of the main engine (head) of the air compressor, in ° C or ° F. Compressor exhaust temperature is an important index of compressor safety. Due to the nature of compressed gas, the temperature resistance of lubricating oil and sealing materials, and the running clearance of rotor, the exhaust temperature is limited. The exhaust temperature is an important performance parameter of air compressor unit.

4. Unit input power

Unit input power refers to the total input power of the air compressor unit (measured from the three-phase input bus end), unit: kW.

5. Unit input specific power

Unit input specific power refers to the ratio of unit input power and exhaust volume under specified exhaust pressure of air compressor unit: unit input specific power = unit input power / exhaust volume

Its unit is kW / (m3 / min). According to gb19153 energy efficiency limit value and energy efficiency grade of positive displacement air compressor, the limit value of each energy efficiency grade of specific power of air compressor unit is different under different pressure.

6. Gas electricity ratio of air compressor unit (air compressor station)

The gas electricity ratio of air compressor unit (air compressor station) refers to the electric energy consumed by the air compressor unit (air compressor station) for each cubic meter of compressed air output (converted into suction state) during operation, unit: kW * H / m3.

D =E/G

Among them:

D = gas electricity ratio of air compressor unit (kW * H / m3)

E = total power consumption of air compressor unit (kW * h)

G = total air supply volume of air compressor unit in measurement period (suction state) (M3)

The value of gas electricity ratio under a certain pressure can be obtained by dividing the value of specific power under this pressure by 60:

Gas electricity ratio = specific power ÷ 60

7. Diameter calculation of compressed air pipe

In principle, the pressure drop of the piping shall not exceed 5% of the air compressor's operating pressure, so when rounding the calculated value according to the standard pipe size table, the larger one shall not be taken as the smaller one.

Among them:

D - diameter of compressed air (mm);

Q air compressor nameplate discharge capacity (m3 / min)

P - discharge pressure of air compressor (gauge pressure) (MPA);

V - economic velocity of compressed air in the pipeline (M / s).

Reference of economic velocity in the pipeline:

Exhaust pressure: 10-20m / s at 0.1-0.6mpa;

10-15m / s at 0.6-1.0mpa;

8-10m / s at 1.0-2.0mpa.

8. Estimation of air tank size

Among them:

VC - minimum volume of buffer tank, unit: m3;

Q0 - air volume required for normal operation of pneumatic system (m3 / min);

Q outside - air supply at the inlet of air storage tank (m3 / min);

T - time for pipe network pressure to drop from P1 to P2 (min);

P1 - gas pressure stored in the gas tank (MPA);

P2 - the minimum allowable pressure of gas in the air tank (MPA).

The estimated results can be rounded according to the air tank volume specified in fixed reciprocating piston air compressor (JB / t8867): 0.3, 0.5, 1, 2, 3, 4, 5, 6, 8, 10 and 12. The following empirical data of air tank selection are for reference (Q: air compressor unit (station) gas production, minimum volume of air tank)

a) When Q < 6m3 / min, VC = 0.2q

b) When q = 6-30 m3 / min, VC = 0.15q

c) When Q > 30 m3 / min, VC = 0.1q

9. When the air compressor exhaust volume is not enough and the pressure cannot be increased, the air compressor exhaust volume to be increased shall be determined

Among them:

Δ Q - air displacement of air compressor to be increased m3 / min;

Q original - original air compressor discharge m3 / min;

P real - the target working pressure that the system needs to achieve bar;

P original - the working pressure bar that the original air compressor can reach.