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The coal quality characteristics of urban sludge were analyzed, and three types of coal-sludge-coupled power generation technologies were introduced, including direct sludge mixing, flue gas direct drying sludge and steam indirect drying sludge coupling power generation. Three types of sludge coupling power generation technologies in coal-fired power plant were introduced, including direct sludge blending process, sludge blending after drying directly by flue gas and indirectly by steam. The control values of sludge blending ratio and moisture content after sludge drying are analyzed, and it is considered that the direct sludge blending ratio should be controlled within 5%. The moisture content after sludge drying should be controlled at 30-40% and the blending ratio should be controlled within 10%. The influence of sludge blending on the operation of the unit is analyzed. The operation of coal-fired boiler is stable, the quality of fly ash and slag has little change, and the emission of pollutants and heavy metals reaches the standard if the proportion of sludge mixed with combustion is controlled within 10%.

A unit frequently participated in the deep peak load regulation of the power grid. In the process of deep peak load regulation, the time of oil feeding and stabilization of combustion was relatively long, which caused the blocking of the pipeline at the inlet of the ash storage pump at the rear of the electrostatic precipitator. According to the analysis, it was found that it was caused by the spontaneous combustion and coking of mixture of oil and pulverized coal which had not been thoroughly burned in the ash bucket.

After long operation, heat transfer characteristics and flue gas pressure drop of low-pressure economizer are deviated from design value seriously. Through low-pressure economizer retrofit on a 670t/h coal-fired unit, the flue gas pressure drop is decreased to 597.04pa, less than the guarantee value 750Pa, the water saving of desulfurization spraying is 25.92t/h, the reduction of coal consumption for power generation is 2.80g/kW·h. Its energy-saving effect is obvious and transformation expectation is achieved.