General Precautions to Avoid Pyrophoric Iron Fires

1. The scraps and debris collected from cleaning of filters in naphtha / crude service must be kept wet and disposed of underground.
2. Tanks, reactors, columns, and exchangers in high-sulfur feed service must be kept properly blanketed with N₂ during idle periods.
3. All equipment and structured packing must be properly water washed and kept wet when exposed to the atmosphere.
4. In processes where catalyst handling is required (such as in Hydrotreating and fluid catalytic cracking) caution must be taken during catalyst recharge or disposal. When unloading any spent coked catalyst, the possibility exists for iron sulfide fires. If the spent catalyst is warm and contacts oxygen, iron sulfide will ignite spontaneously and the ensuing reaction may generate enough heat to ignite carbon deposited on the catalyst. Therefore catalyst must be stripped of all hydrocarbons, cooled to about 50 ^o C and wetted with water to prevent it from igniting vapors. Once cooled, the used catalyst may be emptied into drums for later shipment to a regenerator or a disposal site. As the catalyst may be highly pyrophoric (containing iron sulfide, etc.), it should be dumped into drums containing an internal liner for shipment. The drum and liner should first be filled with inert gas, which is then displaced by the catalyst. The liner should be tied off and a small chunk of dry ice placed inside the drum before sealing. These precautions should protect against catalyst auto ignition.

References

1. "Pyrophoric Materials Handbook, Flammable Metals and Materials", By Charles R. Schmitt, P.E., C.H.C.M., Edited By Jeff Schmitt
2. "Pyrophoric Fires and Column Shutdown", Refineries Quarterly Safety Bulletin, April-June 1997.
3. “Oxidizer Use in Refinery Chemical Cleaning: Selection Considerations and Case Histories”, presented at NACE, Chris Spurrell (Chevron) and Ron Kenyon (Delta Tech Services)
4. "Methods for Removal of Iron sulphide", Mr. Fu Huang, Chinese American Association of Corrosion & Materials Engineers
5. "Formation and Oxidation of Sulfides on Pure Iron and Iron Oxides", Masatoshi Watanabe1, Minoru Sakuma, Takeshi Inaba, and Yasutaka Iguchi, Department of Metallurgy, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan
6. “Basic Technology of Zyme-Flow Process”, Bevan Collins, International Technical Director, United Laboratories, LLC , www.zymeflow.com
7. TECHNICAL BULLETIN: Safe Handling of CRITERION Hydrotreating Catalysts
8. www.worlfuels.com, NPRA Q&A Minutes, 1999 Session I