Project Profile:The first 13E2 gas turbine unit of Shenzhen Nantian Power Plant was imported from ABB in Switzerland in the early 1990s with an installed capacity of 240 MW. The original design considered the sulfur corrosion problem of using light diesel oil, so the single pressure design was adopted in the combined cycle, and the exhaust gas temperature of the HRSG outlet reached 180 ℃ after oil-natural gas conversion which resulted in a great waste of energy. In order to reduce the gas consumption of power generation, Nantian Power Plant invited NTPS to organize and implement the double pressure conversion of HRSG and steam turbine.  After carefully design and preparation, the double pressure conversion project was finished in 45 days and the parameters of the unit are stable during operation. Combined cycle output increased about 8MW and efficiency improved about 1.5% under similar environmental conditions.