"One Furnace and Two Storage Systems" Giving Flexible Wings to Coal-fired Power Units

  Coal-fired power generation units have a power generation capacity of hundreds of megawatts, with essential characteristics of large delays and inertia. Enabling coal-fired power units to operate flexibly is like letting a "clumsy" elephant run around quickly like a monkey. It is obviously very difficult. Meanwhile, a new power system with a high proportion of new energy requires matching flexible and schedulable resources. Therefore, the flexibility transformation of in-service coal-fired power units and the related research and development of intrinsically-flexible new units have become key topics in China's energy transition process.

  Huairou laboratory research team innovatively proposes the design concept of "one furnace and two storage systems". The coal-fired flue gas heats both the water tank and the molten salt tank. This structure creates a new "coal-water-salt" thermal-mass coupling mode, giving a pair of flexible wings to coal-fired power units characterized with large delays and inertia. The boiler originally heating water can achieve long-term safe and stable operation at 15% of its rated load by adopting the system-wide low-stress flexible structure design and the ultralow-load stable combustion burner. The introduction of the molten salt storage system can instantaneously supplement the load of the unit and realize rapid load changing of the unit. Compared with conventional coal-fired power units whose actual operating load change rate is about 2%, the new coal-fired power unit with the aforementioned structure can increase the operating load change rate to 6%, hence reaching the international advanced level.

  The new solution has given flexible wings to traditional coal-fired power units. The "elephant" is no longer clumsy. It can not only respond quickly to load changes, but also operate safely and stably at low load for a long time to consume new energy power. In the event of power shortage, it can also operate at full capacity to ensure the power supply of the power grid. "One furnace and two storage systems" not only realize the flexible operation of coal-fired power units, but also lay a solid foundation for the integration of new energy power into the grid in large scale.