Heater tubes purge steam

One way to combat this problem is with steam. As soon as the flow is interrupted, high-pressure purge steam is automatically opened into the heater tube inlets. The steam blows the residual liquid out of the tubes, and also helps remove heat from the tubes. 

The correct way to prevent this sort of firebox explosion is to use firebox purge steam. A typical heater firebox might have a half dozen 3-in purge steam connections. The idea is to displace the air in the firebox with steam. Then, the flows of combustible process liquid and fuel gas may be safely stopped, without fear of entering the explosive region. This purge steam is different from the purge steam used in the heater s tubes. 

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