Patent ID: 7317073

Claim:
A method for producing vacuum and for separating condensable components present in vapor which accumulates during the production of a polymer by melt-phase polycondensation under vacuum in at least one reaction step, which comprises the step of: (a) effecting a vacuum in a reaction step by means of at least one steam-jet vacuum pump to which a working vapor consisting of at least one alkylene carbonate in vapor form, and/or at least one dialkyl carbonate in vapor form is added together with the vapor which accumulates containing condensable components, resulting in the vapor which accumulates containing condensable components being drawn off and mixed with the working vapor; and (b) condensing the condensable components present in the mixture obtained in accordance with step (a) in one downstream injection condenser per steam-jet vacuum pump by spraying the mixture with a coolant consisting of at least one liquid alkylene carbonate and/or at least one liquid dialkyl carbonate to accumulate a condensate as a sump product and a vapor phase as a head product.