二次再热机组高效灵活发电创新理论与方法

Regarding the problems such as low economic performance and lack of flexibilities during the operations of double-reheat ultra-supercritical coal-fired power generation unit under frequent load change conditions, this paper studies the innovative theory and methods for high-efficiency and flexible power generation of ultra-supercritical double-reheat coal-fired power generation unit. Firstly, on the base of the specific fuel consumption method, the energy consumption distribution regularities of a traditional double-reheat coal-fired power generation unit under different load conditions are revealed. Then five types of new advanced double-reheat coal-fired power generation systems are proposed in this paper, which are all designed with the main steam temperatures of over 600 °C and more advanced capabilities of accommodating the peak load regulations, i.e., double-reheat power generation cycle integrated with the regenerative small steam turbine, double-reheat power generation cycle with the deep coupling between the boiler and turbine system, new double-reheat power generation cycle with CO₂ as the working medium, double-reheat power generation cycle with energy storage system and double-reheat power generation cycle integrated with the solar energy, respectively. Their ideas of integration and characteristics of these new cycle systems in improving the economic performance and operation flexibility are elaborated in details. The research results are illustrated as follows: boilers, steam turbines and regenerative heaters have great energy-saving potential; the standard coal consumption rate of the optimized double-reheat power generation cycle with the regenerative small steam turbine is 2.15 g/(kW·h) lower than that of the reference system; the coal consumption of double-reheat power generation cycle with the deep coupling between the boiler and turbine system can be reduced by 3.6 g/(kW·h) under THA condition; the coal-fired power plant with CO₂ as the working medium still has high efficiency even under load variation conditions; the double-reheat power generation cycle with energy storage system has better flexibility, while the double-reheat power generation cycle integrated with the solar energy has significant energy-saving potential, which can reduce coal consumption by as much as 14.73 g/(kW·h).