Correct Answer - Option 4 : Back pressure
Concept:
Back pressure turbine: In a back pressure turbine the pressure at exhaust from the turbine is the saturation pressure corresponding to the temperature desired in the process heater, the exhaust steam from the turbine is utilized for industrial heating purposes.
Pass-out Turbine: When the heating steam flows is less than that required at the factory, pass out turbines are used in that cases where a certain amount of steam is continuously extracted from the turbine at intermediate stage for heating purposes at the desired temperature and pressure.
