There are three primary WHR systems currently available.

  • The first is the Steam Rankine Cycle (SRC) system, which is the most commonly in cement plants, using water as the working fluid and involving generating steam in a waste heat boiler, which then drives a steam turbine.
  • The second is Organic Rankine Cycle (ORC) system, which use a high molecular weight organic liquid such as butane or pentane as the working fluid, with a lower boiling point, higher vapor pressure, higher molecular mass and higher mass flow compared to water. ORC systems can be utilized for waste heat sources as low as 150, whereas SRC systems are limited to heat sources greater than 260.
  • The third is the Kalina Cycle, which is another Rankine cycle that uses a mixture of water and ammonia as the working fluid, until now the number of suppliers is limited as well as the operational experience.

Steam Rankine Cycle systems account for about Ninety-Nine (99) percent of the existing cement WHR installations, leaving only about One (1) percent for ORC and Kalina Cycle systems. Conch Kawasaki's cement WHR technology adopts the SRC.