A method for controlling the reheat steam temperature of a double reheat unit

Abstract

The invention discloses a secondary reheating unit reheating steam temperature control method. The secondary reheating unit reheating steam temperature control method comprises a flue gas recirculation fan variable-frequency control method and a flue gas adjusting baffle opening degree control method; and a leading differential feedforward unit for the reheating steam temperature after water spraying and a feedforward unit for load changing are arranged in each control method, and meanwhile an overriding and locking control unit for special circumstances is arranged in each control circuit. According to the secondary reheating unit reheating steam temperature control method, the problems that the primary reheating steam temperature and the secondary reheating steam temperature of an ultra-supercritical secondary reheating unit intercouple with each other and are low in adjusting speed are solved, the total heat absorption capacity of a primary reheater and a secondary reheater is controlled through flue gas recirculation fan variable-frequency controllers separately, the primary reheating steam temperature and the secondary reheating steam temperature are controlled through reheater flue gas adjusting baffles, the control measures such as feedforward, overriding and locking are taken, the control precision and the response speed of the primary reheating steam temperature and the secondary reheating steam temperature of the ultra-supercritical secondary reheating unit are achieved, and meanwhile safe and stable running of the unit is guaranteed.

Description

technical field [0001] The invention belongs to the technical field of ultra-supercritical double reheating unit control, and relates to a method for controlling the reheating steam temperature of a double reheating unit, in particular to a method for controlling the reheating steam temperature of a boiler for a double reheating thermal power unit. Background technique [0002] According to the national sustainable development strategy and energy-saving and emission-reduction requirements, the thermal power industry has developed towards higher parameters in recent years, and supercritical, ultra-supercritical, and even double-reheat thermal power generating units have emerged. At present, domestic reports have already The number of double-reheat thermal power generating units put into operation is small, and the design of reheat steam temperature control scheme is still a difficult point in the control of double-reheat unit. [0003] For the double reheat unit, the current ...

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Problems solved by technology

[0004] The temperature of the reheat steam on the primary and secondary sides is coupled to each other. If the temperature of the reheat steam on one side is too high or too low, the adjustment of the baffle will inevitably cause the tail of the boiler to flow through the primary reheater and the secondary reheater. Changes in the flue gas volume of the flue will inevitably lead to fluctuations in the reheated steam temperature on the other side, and the flue gas baffles on both sides move frequently and the adjustment speed is slow

[0005] When the temperature of the reheat steam at the primary and secondary sides deviates from the normal value, the flue gas baffle at the boiler tail will move at the same time, and the action at this time will lead to further deterioration of the heat transfer of the flue gas at the boiler tail, making it difficult to successfully adjust the reheat steam temperature, but the response speed is difficult to meet the actual operation demand through the swing burner adjustment

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