适应环境温度变化的直接空冷机组空冷系统控制策略研究

从汽轮机背压调节、风机电耗、防冻控制等方面分析了环境温度变化对直接空冷机组空冷系统控制的影响,提出了与环境温度相适应的直接空冷系统控制策略。风机转速判断方式适宜于夏季风机列的自动投入、退出控制,且风机调速主控宜采用可变参数,随温度升高加强调节作用,而冬季风机列的投入控制更宜选择汽轮机背压判断方式;顺流风机防冻保护控制随冬季气温由高至低变化可依次采用停运触发保护街区的顺流风机、停运与逆流管束单元相邻的风机列和提高汽轮机背压设定值的方式;在冬夏季节温差大时宜分开投运隔离和非隔离街区风机,反之以分步方式投运隔离和非隔离街区风机;在冬季环境温度低时宜采用分步方式投运逆流风机。

STUDY ON CONTROL STRATEGY OF AIR- COOLING SYSTEM FOR DIRECT AIR- COOLED UNITS TO SUIT THE AMBIENT TEMPERATURE CHANGE

The influence of ambient temperature change upon the direct air-cooling system control has been analysed from aspects of the turbine’s backpressure control,the fans’ electricity consumption,and the anti-freezing control etc.,a control strategy for direct air-cooling system being put forward to suit the ambient temperature change.The control mode based on fan speed is suitable for switching the fan row automatically in summer,but the control mode based on turbine’s backpressure is more favorable for switching on the fan row in winter.In summer,the speed-setting controller of fans is suitable to adopt variable parameters,so as to strengthen the adjustment effect as the temperature raises.When the ambient temperature in winter changes from high to low,the anti-freezing protection of downstream fans could adopt sequentially the method of stopping the fans belonging to the row which triggers the protection,stopping fan rows adjacent to the upstream tube bundle block and increasing the set point of turbine’ back pressure.When large temperature difference occurred in summer and winter,the fans in isolated and non-isolated streets have to be put into operation separately.In case of the temperature difference being small,the fans in isolated and non-isolated streets have to be put into operation stepwise;under low ambinet temperature in winter,the counter flow fans are suitable to put into operation stepwise.