A Waste Heat Recovery Unit (WHRU) is an energy recovery heat exchanger that transfers heat from process outputs at high temperature to another part of the process for some purpose, usually for an increased efficiency. The WHRU is a tool involved in cogeneration. Waste heat may be extracted from sources such as hot flue gases from generator, furnaces, thermal oil heaters, kilns and steam from cooling towers, or even wastewater from cooling processes such as in steel cooling.
WASTE HEAT RECOVERY VIA ORGANIC RANKINE CYCLE
The Organic Rankine Cycle's principle (ORC) is based on a turbo generator working as a conventional steam turbine to transform thermal energy into mechanical energy and finally into electric energy through an electrical generator. Instead of generating steam from water, the ORC system vaporizes an organic fluid, characterized by a molecular mass higher than that of water, which leads to a slower rotation of the turbine, lower pressures and no erosion of the metal parts and blades.
- Zero use of fuel.
- Ensures higher efficiency of turbine.
- Simple stop and start up procedures.
- Good system efficiency at partial load.
- Very long lifetime, (around 25 years).
- No water consumption.
- No need of manpower to run the system.
- Simple and low maintenance.
- Excellent operational performance: >98% availability