Control method for improving water balance dynamic characteristics of string tower desulfurization system

Abstract

The invention relates to a control method for improving the water balance dynamic characteristics of a string tower desulfurization system, and belongs to the technical field of water balance controlof desulfurization in a thermal power plant. The control method comprises the following steps: S1, monitoring the gypsum concentrations, the change rates of the gypsum concentrations, the duration ofthe slurry discharge and the variation curves of the gypsum concentrations in a slurry discharge interval period in the primary tower and the secondary tower on line; S2, if the change rates of the gypsum concentrations of the primary tower and the secondary tower are both more than zero, and the gypsum concentration in the primary tower or the secondary tower reaches the stop threshold of a discharge pump, recording the current time value t0; S3, calculating and predicting the starting time and the ending time of next slurry discharge processes of the primary tower and the secondary tower; and S4, establishing a slurry discharge time control method according to the starting time and the ending time of the next slurry discharge processes obtained in the step S3. According to the method, simultaneous discharge of gypsum slurry into a gypsum dehydration system by the primary tower and the secondary tower is avoided, and the water balance dynamic characteristics of the string tower desulfurization system are improved.

Description

technical field [0001] The invention belongs to the technical field of desulfurization water balance control in thermal power plants, and relates to a control method for improving the dynamic characteristics of water balance in a string tower desulfurization system. Background technique [0002] In order to meet the national requirements for ultra-clean emissions from coal-fired power plants, thermal power plants generally transform the original single-tower desulfurization system into a string-tower (double-tower) desulfurization system. When the flue gas flows through the first-stage tower, it will take a large amount of water to the second-stage tower, causing the water level of the first-stage tower to decrease and the water level of the second-stage tower to rise. The common practice is: directly send the slurry in the secondary tower to the primary tower through the discharge pump, and when the gypsum slurry is discharged from the secondary tower to the gypsum dehydrat...

AI Technical Summary

Problems solved by technology

However, under certain working conditions, it is difficult for the series tower desulfurization system to achieve the water balance in the tower. For example, when the sub-equipment and the system of the system are in normal operation, the most dangerous working condition of the water balance of the series tower desulfurization system: the first and second towers discharge gypsum Slurry to gypsum dehydration system, while the filtrate is discharged to waste water, and the pH value in the tower is stable within the control value range (that is, no need to replenish limestone slurry)

Under this working condition, the secondary tower is not sufficient to supply water to the first tower, and the external effluent will easily cause the liquid level of the first tower to drop rapidly

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