Two recent orders for 15 MW steam turbines announced by Peter Brotherhood of the UK reflect Pakistan’s increasing interest in boosting the efficiency of diesel engine power plants by converting them to combined cycle. This involves the addition of turbines using steam generated from exhaust gas heat.

One of the Peter Brotherhood machines is for a refinery power plant employing nine 17 MW four-stroke diesel generator sets. The steam turbine and gearbox will be mounted on a combined bedplate, which incorporates an electronic governor, a PLC-based control and monitoring system and an air-cooled generator.

Colin Lake of Peter Brotherhood said “The specification for this new power plant included an overall cycle efficiency requirement that could only be met by the inclusion of a steam-turbine-based waste heat recovery system. With the increasing requirement for higher cycle efficiency and the continuing high price of fuel, it looks certain that more diesel engine power plants will have to be turned into combined cycle plants…”

The other steam turbine is for a 200 MW power plant with 11 four-stroke diesels to be built in Lahore. Owned by IPP Nishat Power Ltd, the combined cycle plant is due to be fully operational in September 2009 and a minimum overall cycle efficiency of 53% has been specified.