Vapor recompression: An interesting option for vacuum columns?

Abstract

The need to reduce greenhouse gas emissions and decrease the use of fossil fuels will greatly change the design of process plants. Besides improved heat-integration, an obvious option to achieve more sustainable operations is to make use of highly efficient and therefore smart methods of electrification. Hence, heat pumps and vapor recompression systems effectively recirculating “waste” energy to the process may become economical in applications where experience had quickly eliminated them in the past. In this changing socio-economic context, process engineers will have to re-think, challenge and even un-learn many accepted design practices. One example is the use of vapor recompression in distillation. While applications in close-boiling high pressure systems have been reported in literature, the number of actual realizations is comparatively small. In vacuum systems, the practical hurdles are even higher, since large volumetric flowrates result in high compressor investment. In this paper, alternative designs are presented opening the way to electrification of a well-known vacuum system. Furthermore, the advantageous application to wide-boiling systems is demonstrated in two examples.