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Crude Unit Start-up: Consequences of High Liqiud Level

 

Summary

Following a crude unit revamp high liquid level during start-up caused the heavy diesel product to turn black. Yet because the internals were designed for severe uplift, no damage occurred.

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National Petroleum Refiners of South Africa Ltd. (Natref) revamped their crude unit in 2002 to increase capacity. Natref revised the start-up and operating procedures to reflect the extensive flow scheme changes, which included many new pieces of equipment. Nonetheless, even after careful planning abnormal events can take place during start-up. Experienced operators often talk about high liquid level that can occur during start-up as a normal event, not an unusual occurrence. Relying on level instrumentation alone is not sufficient to
avoid high level and its consequences during start-up. Pressure is a very simple, yet often overlooked measurement that operators and start-up personnel can use to help avoid high column levels and the resultant problems (Photo 1).

Start-up can be a very dangerous time.Flow rates and levels are changing rapidly. Many things are occurring all at one time. Many crude units experience internalsdamage during start-up...

 

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Tags: CDU, VDU