How to adjust the capacity of refrigeration compressor

How to adjust the capacity of refrigeration compressor The capacity of the compressor is determined according to the maximum production of BOG in the storage tank. After the compressor is selected, its capacity is constant. If the amount of inhaled air is greater than the amount of BOG produced in the tank, the tank pressure will drop. When the tank pressure drops to a certain level, in order to compensate for the lack of air at the inlet of the compressor, the following two measures can be taken: 　　 First, the compressor second outlet gas phase returns to the inlet flash tank D～2, that is, the control circuit part of the valve PV-2 is controlled by the D-2 pressure P-2 in the figure. 　　Here, the setting value of P-2 is 300KPa. If the pressure of D-2 is higher than this value, the valve PV-2 is closed. If the pressure of D-2 is lower than this value, the valve PV-2 will be opened to return to the gas phase. 　　 Second, the suction volume can be reduced by unloading the compressor inlet, that is, reducing the compressor capacity from 100% to 50%. For the diaphragm-type (Diaphragm-type) unloading device, the inlet air valve unloading device operated by the instrument wind restricts the free movement of the valve plate and keeps the inlet air valve open. 　　 Because the inhaled gas is not compressed and is discharged back to the inlet. In this way, if one end of the double-acting cylinder (cylinder end or crankshaft end, generally the cylinder end) is unloaded, the capacity of the compressor becomes 50%. If both ends are unloaded, it becomes 0%. When the compressor inlet gas deficiency is less than 50% of the compressor capacity, the above one method is used, that is, gas phase return; and when the shortage is greater than 50% of the compressor capacity, the above two methods are used, that is, the compressor is reduced to 50%.