The oil-in-water type screw compressor 2 includes an arithmetic unit 36 that calculates and obtains a remaining water amount Dr based on at least the suction temperature Ts, the suction pressure Ps, the discharge temperature Td, and the discharge pressure Pd, The first rotation speed of the motor 14 is compared with the second rotation speed of the motor 14 where the discharge pressure Pd is the target pressure and the inverter 16 is controlled so as to drive the motor 14 at a higher rotation speed And a flap valve control section 34 for opening the flap valve 12 while the discharge pressure Pd exceeds the flameproof pressure when the inverter control section 32 and the first rotation speed motor 14 are driven And a control device. The oil-tight screw compressor (2) prevents water from accumulating in the oil separation / recovery device, and immediately starts supplying the required pressure even if the required pressure changes from a low load state in which the required pressure is low to a high load state in which the required pressure is high .
展开▼
