What are the common vacuum producing systems for evaporators and condensers?

Systems include: Steam jet ejectors (no moving parts, reliable, use motive steam, single stage to 100 mbar, multi-stage to 1 mbar), Liquid ring vacuum pumps (handle vapor/liquid mixtures, isothermal compression, 30-80 mbar range), Dry screw vacuum pumps (oil-free, wide range, higher efficiency), and Hybrid systems (ejector first stage + mechanical pump finishing). Selection factors: ultimate vacuum required, vapor load and composition, steam availability, electricity cost, condensable load, reliability requirements, and maintenance capabilities.