热电厂切除高压加热器运行的热经济性研究

Thermal economy research on the stopping of HP heaters in thermal power plant

以cc250-16．67╱1．609╱0．785型机组为例,运用热量法和焓降法,对抽汽凝汽式机组在尖峰电负荷下切除高压加热器运行的绝对内效率和热经济性进行了理论研究。研究结果表明在一定条件下,切除高压加热器后机组绝对内效率可以提高。对于回水入冷凝器的抽汽凝汽式机组,保持新蒸汽耗量不变,在尖峰电负荷下切除高压加热器运行,其绝对内效率与对外供汽量有关。当机组对外供汽量超过某一值时,切除高压加热器获得额外电功率的同时还可提高机组绝对内效率。通过计算其煤耗量,表明切除高压加热器后热经济性始终是降低的,与对外供汽量无关。

Taking cc250-16.67/1.609/0.785 unit for instance, using the calorimetry and enthalpy-drop method, this paper studied the theory of thermal economy and absolute internal efficiency of HP heaters fully-stopped at the peak loads in condensing thermal power units. The results show that absolute internal efficiency of unit increases after HP heaters stopped under certain condition. Typically, as to the condensing bleeder turbine unit with backwater into condenser, keeping the HP heaters out of service at peak load with constant new steam consumption, the absolute internal efficiency of steam turbine is related to extraction steam. That is, additional power and increased absolute efficiency would be gained after HP heaters stopped in case of the quantity of extraction steam exceeds certain value. But the thermal economy decreases according to the calculation results of coal consumption, which is independent of extraction steam.