Objective To address the challenges in the desulfurization systems of coal-fired power units: such as high energy consumption of circulation pumps, excessive desulfurizing agent usage, and severe fluctuations in outlet SO₂ concentration under complex operating conditions like low loads, high-sulfur coal co-firing, and tightening environmental constraints: this paper proposes a multi-objective cooperative optimization strategy for the variable frequency control of slurry circulation pumps. The strategy aims to achieve an optimal balance among desulfurization efficiency, operational costs, and environmental indicators.

Method A calcium-to-sulfur (Ca/S) ratio and liquid-to-gas (L/G) ratio intelligent cooperative control scheme based on the NSGA-Ⅱ was proposed. A multi-objective optimization model was established to minimize operational costs (pump energy consumption and desulfurizing agent usage), reduce outlet SO₂ concentration fluctuations, and ensure emission compliance. Leveraging NSGA-Ⅱ's non-dominated sorting and crowding distance mechanisms, the frequency conversion parameters of recirculation pumps and limestone slurry flow rates were dynamically optimized to generate a Pareto-optimal solution set. Algorithm parameters were validated using engineering data.

Result Engineering applications demonstrate that the proposed method achieves balanced allocation of slurry circulation pump output and slurry consumption under load-increasing/decreasing and steady-state conditions. After implementation, the average hourly power consumption of five slurry circulation pumps was reduced by 21.7%, yielding annual electricity cost savings of 1.335 million CNY. The unit powder consumption decreased by 26.7%.

Conclusion The research effectively addresses the challenges of strong multivariable coupling and poor adaptability to dynamic conditions in desulfurization systems, significantly reducing operational costs while enhancing environmental performance. It provides a valuable technical pathway for coal-fired power units to achieve synergistic optimization of economic operation and ultra-low emissions, holding significant engineering value for promoting the intelligent upgrading of the wet flue gas desulfurization process.