燃气-蒸汽联合循环机组汽轮机冷态预暖技术应用及优化

Application and optimization of cold-state preheating technology for steam turbine of gas-steam combined cycle unit

燃气-蒸汽联合循环机组(简称“联合循环机组”)在冷态启动过程中,由于汽轮机金属温度低,为了避免冲转过程中产生的热应力影响机组安全,汽轮机需要进行中速暖机,以提升汽轮机金属温度,这一过程极大地限制了机组快速响应电网调峰的能力。对此,在联合循环机组中首次应用汽轮机预暖系统,并对汽轮机预暖系统投入前、后机组的2次冷态启动过程进行对比。结果表明:预暖系统可以使汽轮机在冷态整套启动前达到温态启动要求,极大地缩短了冷态启动下机组的启动时间,提高了机组的经济性。此外,通过对机组冷态预暖过程的优化改进,有效地避免了汽源压力不足造成机组转速快速下降的现象。该经验可供相关联合循环机组参考。

During the cold state start-up of gas-steam combined cycle unit,the metal temperature of steam turbine is low,in order to avoid the thermal stress generated during the rotation process affecting the unit safety,the steam turbine needs medium-speed heater to increase the metal temperature,which greatly limits the ability of the unit to quickly respond to peak regulation of the power grid.Therefore,steam turbine preheating system is applied in the gas-steam combined cycle unit for the first time,and the twice cold state start-up processes of the unit before and after the steam turbine preheating system is put into operation are compared.The results show that,the preheating system can make the steam turbine reach the warm state start-up requirements before the whole cold state start-up,which greatly shortens the start-up time of the unit under the cold state start-up and improves the economy of the unit.In addition,through optimization for cold-state preheating process of the unit,the phenomenon of rapid decline of the unit speed caused by insufficient steam source pressure is effectively avoided.This experience can be referred for the relevant combined cycle units.