(18a) Ammonia Mitigation System for Large Release Scenario in Storage Tanks - a Case Study

Anhydrous ammonia has high toxicity (tolerability ≤ 20 ppm) and flammability, and is generally transported on ships, trains, tank trucks, and pipelines. It is raw material to produce fertilizers and an effective coolant used in industry. Supplied in liquefied state, vaporizes immediately at atmospheric pressure forming a dense floating cloud. At Usiminas Steel plant anhydrous ammonia is generated as a subproduct of the metallurgical coke manufacturing process and is stored in pressurized liquefied state (15 bar) in seven tanks of 123 m³ each. An automatic ammonia mitigation system, with 5 s response time, was developed and built in the storage tank and truck loading area to neutralize 100% in the worst scenario of leakage (7,668 kg/h – 12 m³/h). Ensuring safety and low risk for the industrial plant. Ammonia leak neutralization tests were carried out and demonstrated the water spray nozzle efficiency.