The vacuum tower and all associated equipment were cleaned simultaneously. Typically, the refinery staff would solvent wash and steam the tower for up to 72 hours in a turnaround prior to allowing vessel entry. Our process took 36 hours to clean the equipment saving the refinery 1 ½ days of outage time. The towers are packed with rachig rings and had chimney trays which become encrusted with a high-molecular weight contaminants.

Chemical cleaning had been tried on several previous occasions with nominal success leaving the vessel contaminated with residual hydrocarbons and pyrophoric iron deposits. Typically, the chemical wash was followed by high-pressure water blasting to achieve the level of cleanliness required.

After 36 hours of circulation at 60°C (140°F), the tower was drained. Upon opening the manways, the packing was found to be cleaned of the contaminant and was “cleaner than we have ever seen this equipment”. The pyrophoric deposits were eliminated during the washing step.