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I have a general query related to hydrotreaters. I want to know what are the factors considered in designing push/pull system for feed surge drums. I saw some units operating with Fuel gas while some operate with Nitrogen as supply for blanketing.
 
Answers
17/06/2017 A: Ganesh Maturu, Self, maturu.ganesh@gmail.com
General practice is to use Fuel Gas as blanketing gas. However, nitrogen can be used some times but it may reduce the purity of recycle gas because of some nitrogen dissolves in Feed and circulates in reactor loop. Hence it is advisable to use Fuel Gas. If fuel gas contains oxygenates like CO, CO2 and H2S, it is recommended to use H2 as push-pull system.
06/06/2017 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
Fuel gas is the standard. However, using nitrogen simplifies complying with local air quality standards. Where does the vented gas go? Some plants vent nitrogen directly to atmosphere If fuel gas, it would go to the flare header, and be routed from the flare gas compressor to a gas plant.
06/06/2017 A: ARUN RS, INDIAN OIL CORPORATION LTD, arunrskmr@gmail.com
For Hydrotreating feed surge drums always blanket with nitrogen...if Fuel gas there it can contaminate the feed to the reactors...Where as other systems like Sour water , Amine, naphtha cracker surge drums are blanketed with Fuel gas where impurities of fuel gas is not a problem