Optimal control method for flue gas circulating fluidized bed desulphurization

Abstract

The invention discloses an optimal control method for flue gas circulating fluidized bed desulphurization in the technical field of thermal power plant desulphurization. A DCS system is connected with a flue gas circulating fluidized bed and a PLC-based sulfur dioxide optimal control system. The sulfur dioxide optimal control system is formed as follows: a sulfur dioxide prediction module and a carbon dioxide calculation module are respectively connected with a data communication module and a hydrated lime control module, and the hydrated lime control module is connected with the data communication module. The data communication module and the DCS system exchange data. According to the invention, the content of CO2 in the flue gas at the inlet of a desulfurization tower is calculated through an SO2 prediction model. The feeding amount of hydrated lime can be adjusted timely, dynamically and accurately. Excessive emission of SO2 and the waste of hydrated lime and resources are avoided fundamentally, and CO2 emission is reduced to a certain extent. The method is of high reference value in engineering.

Description

technical field [0001] The invention belongs to the technical field of desulfurization of thermal power units, and in particular relates to an optimal control method for flue gas circulating fluidized bed desulfurization. Background technique [0002] Circulating fluidized bed flue gas desulfurization technology is a new type of desulfurization process developed in the 1980s. It originated from the roasting process of cement and metallurgy. It is based on a circulating fluidized bed, through multiple cycles of the absorbent, prolongs the contact time between the absorbent and the flue gas, greatly improves the utilization rate of the absorbent, and can approach or reach the wet process at a lower calcium-sulfur ratio desulfurization efficiency. Circulating fluidized bed dry desulfurization technology has a simple system and relatively low speculation, which has gradually attracted the attention of more and more countries. This technology is a flue gas with the largest singl...

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Problems solved by technology

Obviously, there is a large delay in the output signal of the gas analysis instrument, and the real-time performance is poor for the control loop. If it is used directly, it may cause the oscillation of the control loop, so it cannot be used as a direct adjustment parameter; secondly, the flue gas volume caused by the boiler load fluctuation The large change of the gas also caused great difficulties to the measurement and adjustment; thirdly, due to the stricter and stricter requirements of the state on flue gas emission indicators, if a higher desulfurization efficiency is to be achieved, a large amount of desulfurizers must be added, and a large amount of The slaked lime will stay in the desulfurization tower, which will affect the circulation of the desulfurizer in the desulfurization tower, and the problem of the bed is prone to occur, and the large consumption of slaked lime will increase the Ca / S molar ratio and increase the operating cost

In addition, excessive desulfurization agent will bring a large amount of additional ash and physical heat loss, and at the same time increase the wear of the desulfurization tower furnace, affect the desulfurization working conditions, and then increase the cost and affect the economical efficiency of desulfurization

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