Emergency relief treatment systems

Design of Emergency Relief and Effluent Treatment Systems... 

Containment systems are only rarely designed with sufficient pressure and temperature rating to fully contain a runaway reaction. For this reason, overpressure protection is of obvious critical importance as a last line of defense against loss events that can result from runaway reactions. The latter sections in this chapter on Pressure Relief Systems and on Emergency Relief Device Effluent Collection and Handling address design basis selection, relief calculations, and effluent treatment system configurations for reactive system overpressure protection. 

Figure 1.7 Schematic diagram of the emergency relief effluent treatment system that includes a scrubber and flare tower in series in the Bhopal Union Carbide process.

The process vessels are equipped with vents to prevent pressure build up by inert gases. These vents are also used to depressurise and flush equipment during emergencies and prior to maintenance. Usually, vents are connected to air pollution control equipment, except major relief vents which, due to large flows, would overload the treatment system. 

Design downstream treatment system. Estimate maximum flow through emergency relief system to give maximum load on downstream equipment. 

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