Phosacid Plant Revamp
J.R. Simplot, Pocatello, ID

This project included the process design and start-up services for modernization of a large fertilizer plant at Simplot's Don plant in Pocatello. The process improvements reduced direct losses of phosphoric acid to the cooling tower system, and at the same time recovered hot water for re-use in the process. Also, major air pollution control systems were designed and installed.

The principal process innovation was adding a pre-condenser system on the slurry flash coolers. The system recovers entrained phosphoric acid mist and generates hot water for filter cake washing. This also enabled redesign of the cooling water circuit and reduced the cooling tower load by 25 percent.

New fume scrubbers were designed to treat 120,000 cfm of storage tank and filter equipment vents. These technologically advanced scrubbers meet the most stringent EPA and local codes for fluorine emissions. The system was designed and implemented in five months. Detailed engineering was provided by Bithell Engineering, Pocatello, Idaho. More details of this project can be found in a paper presented at the AIChE Clearwater Convention, May 1995.

Project Highlights:

• Payback for the project was 2.2 years (IRR = 36%).
• Excessive P2O5 losses from the Flash Coolers were eliminated and the instantaneous plant capacity was increased by 15%. 
• More vacuum capacity was provided with a reduction in the size of the vacuum pumps.
• A planned new cooling tower cell was not required.