Nitrogen Rejection Unit, The Right Selection

Presented at Annual Conference, 13 - 15 September 2017 at Sofitel Chain Bridge Hotel, Budapest by
Nicolas Chantant, Paul Terrien & Sylvain Gerard, Air Liquide Global E&C Solutions France
Nitrogen Rejection Unit (NRU) covers many applications and technologies. The only common thing to all of those units is the fact that nitrogen is removed from the final methane product to reach a certain purity or Higher Heating Value (HHV).
Focusing on Cryogenic Nitrogen Rejection Units which is the only option available in many cases the main generic process categories will be presented as well as their potential variants. The paper will then present some general trends outlining the objective criterias that will help define the best solution. The paper will specifically point out the effect of some critical factors such as:
• Feed conditions and nitrogen concentration
• Product methane and rejected nitrogen specifications
• Composition variation of the feed gas
In doing so some unexpected effects will be highlighted such as higher feed N2 content impact on the total cost of ownership.