Abstract: Process for multi-stage generation of a vacuum and condensation and recycling of the vapors of polycondensation in the production of polyester, where the last stage includes a liquid ring pump compressing to atmospheric pressure, a cooler and a degasifier tank. The process also includes at least two preceding stages each using a glycol vapor jet that is operated with superheated glycol vapor at a pressure in the range of 0.8 to 1.0 bar abs. and a downstream glycol spray condenser whose operating conditions are regulated to condense a maximum quantity of glycol and at the same time causing the low-boiling reaction by-products including water to remain in the gas phase.