Turbine Classification 

The turbines may be classified based on the process condition, they are

• Condensing turbine
• Non-Condensing turbine
• Extraction turbine

Condensing turbine

• The input to the turbine may be from a single source or from a number of boilers connected to a steam bus and then supplied
• The output may be condensing in which the exhaust pressure is sub-atmospheric (vacuum)
• The condensed water is recirculated back into feed water stream to avoid treatment of more freshwater
• Here the makeup water requirement is kept at minimum

Non-Condensing turbine

• The input to the turbine is similar to that of condensing turbine, but the output may be ‘non-condensing’ in which the exhaust pressure is greater than atmospheric
• Such a turbine is also called backpressure turbine
• The steam that exhausted with some pressure may be utilized as process steam for other purposes in the plant
• Such a steam is called process steam or intermediate pressure steam or low pressure steam

Extraction turbine

• Both in condensing and non-condensing turbines, the outlet from the turbine is only one.
• One or two more outlets may be provided to extract steam at different pressures for other uses
• Such a turbine is called extraction turbine
• It may be condensing or non condensing