Energy Comparison Vacuum Producing Equipment - Mechanical Vacuum Pumps vs. Steam Ejectors

Abstract

With manufacturing facilities placing increased emphasis on operating costs and environmental protection, replacement of inefficient or wasteful process methods is being considered.

In the past, the accepted method for drawing or maintaining a vacuum on condensers, process reactors, or equipment and processes requiring subatmospheric conditions, has been to utilize steam ejectors. Due to the inherent operating inefficiency and wastefulness of the steam ejector, coupled with the rapidly increasing cost of fuel to produce steam, it has become apparent that considerable savings in operating costs and reduction in thermal or water pollution can be achieved by replacing steam ejectors with mechanical vacuum pumps.

The liquid ring (sometimes called 'liquid piston') type of mechanical vacuum pump is usually selected due to its ability to handle liquid carryover and condensibles in the suction stream. Efficiencies and cost comparisons presented in this paper are based on this type of vacuum pumping device.