Analysis of difficulties and countermeasures for first start-up of waste acid recovery unit
In January 2023,the SAR(sulfuric acid regeneration)unit in the acrylonitrile complex of a petrochemical plant was successfully started up for the first time.The key to improving the conversion rate of waste acid was to reduce the oxygen content in the regeneration furnace.By decreasing the load of the preheating system,the burner load of the regeneration furnace was ele-vated,which effectively diluted the oxygen content in the regeneration furnace,increased the conversion rate of sulfur trioxide to sulfur dioxide,lowered the sulfuric acid content in the weak acid of the purification unit,and ultimately lessened the problem of acid corrosion.By adding the number of backup waste acid spray guns and diminishing the load on a single spray gun,the poor atomization effect of waste acid spray gun and the corrosion of acid water on the regeneration furnace were alleviated.During the start-up phase,condensed acid corrosion and leakage were prone to occur at the fire tubes and smoke boxes of the waste heat boiler.The corrosion and leakage of fluorine lined equipment was mainly related to sealing form of the lining and temperature of the material used.Acid resistant metal hoses need to be lined with PTFE and integrally formed with the flange surface to enhance sealing performance.
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