The towers had never been taken out of service together due to the length of time required to clean each tower. Typically, it took 25 days per tower to mechanically clean each tower by use of high pressure water. The towers are packed with metal turnings which become encrusted with a high-molecular weight contaminant requiring all of the packing to be removed and then mechanically cleaned.
Chemical cleaning had been tried on several previous occasions without success. After 30 hours of circulation at 60°C (140°F), the towers were drained. Upon opening the manways, the packing was found to be cleaned of the contaminant and “appeared as new”. This method of cleaning required 5 days from shut down to returning to production.
The plant estimated that over $100,000 per tower was saved over the conventional method of cleaning and over $2.7 million was gained in additional production.