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Weyerhaeuser Chlor-Alkali Plant - Longview, Washington

Process Hazard Assessment and Operability Investigation

Weyerhaeuser operates a 465 ton-per-day chlorine plant in Longview, Washington. Universal Dynamics personnel assisted Weyerhaeuser by performing a process operability investigation of the chlorine cooling, drying, compression and liquefaction systems for improvements consistent with good industry practice and PSM requirements. A number of equipment and procedural improvements were identified which when implemented will significantly improve the safety, reliability, and efficiency of the chlorine plant.

New Vaporizer Installation Consistent with PSM

The original method of vaporizing liquid chlorine for use at the ClO2 plant resulted in a series of chlorine releases from relief valves. These failures resulted in Weyerhaeuser abandoning the vaporizer system. UDA personnel designed a new vaporizer system that minimizes atmospheric releases by preventing over pressure on the Cl2 vapor side of the vaporizer.

The new vaporizer design uses the pressure of the Cl2 vapor to regulate the flow of Cl2 liquid to the vaporizer heating element. The liquid Cl2 flow to the vaporizer is completely stopped before the Cl2 vapor pressure reaches the emergency relief valve pressure. The vapors from the relief valve were absorbed into a caustic solution to avoid emissions to the atmosphere. Operating procedures consistent with PSM were prepared to minimize the chance of accidental releases.