Abstract: The graphite heat exchanger in the predesilication area of Shougang siliconsteel acid regeneration unit is a blockhole type graphite heat exchanger, which is used to cool the waste acid transported from the pickling line of silicon steel. The content of Silicon mud in the waste acid discharged from the pickling line to the predesilication unit is about 500 mg/L. Since putting into production, the silicon mud blockage of graphite heat exchanger in predesilication area often occurs. In this paper, the structure of the graphite heat exchanger, the typical faults and the existing problems of the current treatment methods were discussed in detail, and the improvement measures were put forward. Through the reasonable selection and optimization of equipment, an online alkaline cleaning system is set up, and the reaction between SiO2 and NaOH is used to generate Na2SiO3 which is soluble in water. Therefore, it is convenient and effective to dredge the graphite heat exchanger online, which improves the input rate of the graphite heat exchanger and greatly reduces the cost of maintenance and spare parts.

Key words: graphite heat exchanger, blockage, silicon mud, alkaline cleaning system