Patent ID: 8820082

Claim:
A screw expander system, comprising: a screw expander, including an expansion space formed by screw rotors meshed with each other, the expansion space being configured for expanding an operating medium, an operating medium inlet and an operating medium outlet communicating with the expansion space, a bearing for supporting a rotor shaft of the screw rotor, an oil inlet for supplying oil to the expansion space and the bearing, wherein the oil inlet includes a first oil inlet communicating with the bearing and a second oil inlet provided at the operating medium inlet and communicating with the expansion space, and an oil outlet for discharging the oil from at least one of the expansion space and the bearing; a main body outlet side line connected to the operating medium outlet and the oil outlet, the main body outlet side line being configured for feeding the operating medium from the operating medium outlet and the oil from the oil outlet; a condenser communicating with said main body outlet side line for condensing a gas in a mixture of the operating medium and the oil discharged by the screw expander and fed by said main body outlet side line; a pump communicating with said condenser for receiving a liquid comprising the mixture of the operating medium and the oil from the condenser, the pump being configured to pressure-feed the liquid comprising the mixture of the operating medium and the oil from the condenser; an evaporator configured for evaporating the operating medium in the mixture pressure-fed by said pump; an oil separating tank provided between said evaporator and said screw expander for supplying the operating medium from said evaporator through an operating medium line to the operating medium inlet of said screw expander, and for supplying the oil from said evaporator to the first and second oil inlets of said screw expander, the oil separating tank having an operating medium containing section for containing the separated operating medium, and an oil containing section for containing the separated oil, and the oil containing section of said oil separating tank being connected via a separated oil supply line to the first and second oil inlets of said screw expander respectively, wherein said operating medium line extends from said oil separating tank to the operating medium inlet of said screw expander and does not receive the separated oil from said separated oil supply tank; and pressure adjusting means provided in the operating medium line between the operating medium containing section of said oil separating tank and the operating medium inlet of said screw expander for invariably causing a pressure downstream of the pressure adjusting means to be lower than a pressure upstream of the pressure adjusting means.