Attached is a very simple process flow diagram. In this continuous process, "phosphoric acid and ammonia are mixed, and a non-hazardous product, diammonium phosphate (DAP) results if the reaction of ammonia is complete. If the proportion of phosphoric acid is reduced, the reaction is incomplete, and ammonia is evolved. Reduction in the quantity of ammonia available to the reactor results in a safe but undesirable product."
At the bottom of the diagram, you will find a list of seven "What If" questions (ONLY address Questions 4 and 5). Each team will address one or two of the questions and develop a consensus on (1) what the potential hazard is; and (2) what remedies would be appropriate to eliminate or minimize the hazard.
Address Questions 4 and 5 ONLY.
DAP in continuous process is produced by feeding gaseous ammonia to phosphoric acid at an ammonia-phosphoric acid ratio of 2 moles of ammonia per moles of phosphoric acid.
4. If valve A is closed ...
In continuous process phosphoric acid and ammonia are mixed and a non-hazardous product, diammonium phosphate (DAP) results if the reaction of ammonia is complete.