Method used for avoiding shutdown of circulating fluidized bed boilers, logical control module, and control system

The invention provides a method used for avoiding shutdown of circulating fluidized bed boilers. According to the method, when a circulating fluidized bed boiler is shut down, a steam turbine main throttle valve is not shut down if quality of main steam is capable of satisfying operating requirements of the steam turbine, and continuous grid-connected operation of a steam-turbine generator is realized. A control loop of the method is composed of input instruction requirement conditions 1, a state judging and processing logic loop 2, and an output instruction logic loop 3. The invention also provides a circulating fluidized bed boiler tripping without turbine tripping logical control module, and a control system provided with the logical control module. The control method is simple; control logic is reliable; control interface is clear; and shut down times of the circulating fluidized bed boilers is reduced greatly.