Secondary reheating unit steam temperature control method considering heat storage of reheater

Abstract

The invention discloses a secondary reheating unit steam temperature control method considering heat storage of a reheater. A secondary reheating unit is additionally provided with primary reheating compared with a primary reheating unit, and the proportion of heat absorption capacity and heat storage capacity of the reheater is large, so that the steam temperature is difficult to control. In order to solve the problem, a difference value between the boiler real-time heat storage capacity and a boiler heat storage capacity set value is processed through a PID controller and then serves as a coal quantity compensation value, and the coal quantity compensation value and a coal quantity instruction are added to obtain a new coal quantity value; the heat brought by the coal quantity compensation value and the difference value between the boiler real-time heat storage capacity corresponding to the moment and the boiler heat storage capacity set value are subjected to a quotient way so as to be recorded as k1; and the product obtained by multiplying the difference value of the real-time heat storage capacity of the reheater and the heat storage capacity set value of the reheater by k1 and the water-cooled wall heat absorption capacity variable quantity caused by the change of the unit flue gas recirculation amount are subjected to a quotient way so as to serve as a flue gas recirculation amount compensation value, and the flue gas recirculation amount compensation value and a flue gas recirculation amount instruction are added to obtain a new flue gas recirculation amount value. According to the secondary reheating unit steam temperature control method considering heat storage of the reheater provided by the invention, the steam temperature quality can be obviously improved, and the investment is low.

Description

technical field [0001] The invention belongs to the technical field of thermal control in thermal power plants, and in particular relates to a method for controlling the steam temperature of a secondary reheat unit considering the heat storage of a reheater. Background technique [0002] The precise control of steam temperature in coal-fired units is of great significance to the economy and safety of its operation. The boiler side parameters of the double reheating unit are high, there are many equipments, and the process is complicated, so its thermal inertia is large, and the steam temperature is difficult to control accurately. In addition, because the double reheat unit has an additional stage of reheat compared with the single reheat unit, the number of reheaters in the double reheat unit increases, and the distribution of heat storage is more obvious, which intensifies the difficulty of controlling the steam temperature. Considering the time-varying characteristics an...

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Problems solved by technology

[0003] The present invention aims at improving the control quality of steam temperature and improving the safety during operation, aiming at the problems of large boiler side inertia and difficult control of steam temperature in the double reheating unit, starting from the essential difference between the transient process and the steady state process

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