Recent energy cost increases and the introduction of anaerobic thermophilic processes as part of wasted industrial process and municipal-sludge digestion has prompted the use of heat recovery exchangers. 

They offer a larger circumference compared to tube in shell. For the same flow area, there is a larger heat transfer surface.

Most plant operators are aware of the need to save money and reduce the environmental impact of their plant through better water management. Typically, this line of thinking results in the development of ways to reduce water consumption.