Liquid-ring vacuum pump preceded by a precompressor

In a vacuum generating system including a liquid ring vacuum pump, a liquid separator and a precompressor, said pump having a gas inlet, a gas mixture outlet and a working fluid inlet, said separator having an input connected to said gas mixture outlet of said pump for receiving a compressed gas and liquid mixture therefrom, said separator further having a fluid output connected to said working fluid inlet of said pump for delivering thereto working fluid at least partially separated from said compressed gas and fluid mixture, said precompressor having a gas outflow port connected to said gas inlet of said pump for delivering thereto partially compressed gas for further compression, said vacuum generating system further including heat transfer means for transferring heat energy from said working fluid to a coolant, said heat transfer means being in the contact with said working fluid circulating between said separator and said pump, said working fluid having a higher boiling point than the boiling point of said coolant,

• the improvement wherein said vacuum generating system includes conduit means extending between said heat transfer means and said precompressor for transporting thereto from said heat transfer means said coolant in vaporized form for driving said precompressor, the operating temperature of said working fluid in said pump and said separator being higher than the boiling point of said coolant.