Thermocompressors are mostly used for re-usage of waste steam resulting in reduced energy costs.  This is done by compressing a low pressure steam line through the thermocompressor. A high pressure steam motive is required to compress the low pressure steam resulting in a combined intermediate steam pressure. 

Thermocompressors can sometimes operate in parralel with a 1/3 to 2/3 capacity. This is allows the system to operate at 33%, 67% or 100% depending on the suction load at a given time.