Application of the Coordination Control Strategy of pH and SO2 Concentration in the Desulphurization Slurry Supply

The desulphurization slurry flow of the coal-fired unit is usually regulated by a single PID loop that controls the pH value of the gypsum slurry. And the desulphurization system is characterized with large inertia and serious hysteresis, which often results in SO 2 concentration of the outlet exceeding the standard, and leads the operators to turn the regulating valve to manual mode. The SO 2 concentration of the outlet was taken into consideration into the optimized control strategy of desulphurization slurry supply introduced in this paper, and it is with the gypsum slurry pH value for cooperative control of the slurry regulating valve. Finally, the experiment proved that after the optimization of the control strategy, the desulfurization loop could be automatically put into operation for a long time, and the SO 2 concentration of the outlet keeps stable, and the comprehensive utilization rate of limestone and the automation level of auxiliary equipment are significantly improved.