In addition to a requirement for unusually large capacity, the equipment designers faced a requirement for 24/7 operation with frequent shutdowns and startups that would place strain on the equipment. Also, acid concentrations varied between two levels, and there was need for long-term, near-continuous operation without maintenance.
To meet the challenge, Metaullics drew upon its experience to deliver an evaporator that was up to speed. It too the form of a custom Impervite impervious graphite shell-and-tube heat exchanger. The unit was 18' long, 17 tons empty and 32 tons flooded.
The project required the full support of Metaullics' engineering staff and field-service personnel. The fertilizer manufacturer also became involved in the process, contributing its own know-how. As an example, engineers from the fertilizer company designed special supports for the shell as well as facility configurations for operational efficiency.
The tube side of the unit had an acid flow of 37,000 gal/min, functioning with an acid temperature of 185oF (85oC). The service side had a steam flow of 100,000 to 130,000 lb/hr. Once assured of adequate capacity, the fertilizer manufacturer focused on a proprietary dampner device that increased resistance to vibration and extended operational life.
When the evaporator began operation, the fertilizer manufacturer confirmed that the unit achieved desired concentrations of acid at a rapid rate. Production figures confirmed they were attaining faster-than-expected production of end product.
The unit is now approaching two years of steady performance without the need for even routine maintenance. Operating efficiency is described by the fertilizer manufacturer as "beyond expectations." Looking back at the challenge, B. David Hudson, Metaullics engineering manager said, "This certainly was an exceptional example of supplier/customer teamwork."