Method and device for controlling opening degree of external bed ash control valve

Abstract

The invention discloses a method and a device for controlling the opening degree of an external bed ash control valve. The method comprises the following steps: determining the target value of the heat absorption capacity of a heated surface, corresponding to the ash inlet amount of an external bed, according to the actual load of a boiler; and adjusting the opening degree of the external bed ashcontrol valve to make the actual value of the heat absorption capacity of the heated surface reach the target value of the heat absorption capacity of the heated surface. The heat absorption capacityof the heated surface can be used as the target value of the opening degree control of the external bed ash control valve in order to reduce a steam temperature deviation caused by a bed temperature measurement error or a tail flue gas flow deviation.

Description

technical field [0001] The invention relates to the technical field of boiler control, in particular to a method and device for controlling the opening of an external bed ash control valve. Background technique [0002] The external bed is an important structural form of a large CFB (Circulating Fluidized Bed, circulating fluidized bed) boiler. It controls the heat absorption of the heating surface through the inlet ash control valve. An important means, where the heating surface generally has a medium temperature superheater, a high temperature reheater and so on. In boiler design, the external bed of the reheater is generally used to adjust the reheat steam temperature, and the external bed of the superheater is generally used to adjust the bed temperature in the lower part of the furnace. [0003] The prior art provides a commissioning scheme for the external heat exchanger of a supercritical circulating fluidized bed boiler, which specifically includes the following com...

AI Technical Summary

Problems solved by technology

However, this scheme uses the bed temperature deviation as the adjustment target value, subject to the limitation of the accuracy of the bed temperature measurement, and uses the coal supply volume and the next secondary air volume as the bed temperature adjustment means. The two adjustment directions are opposite, which is not conducive to the fuel volume and air volume. Coordinated supply of , may result in reduced combustion efficiency

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