LNG must not contain more than 1% nitrogen to avoid storage problems. Many LNG base load plants thus feature a nitrogen rejection unit (NRU) for the safe and economical removal of nitrogen. Not only does this reduce transportation volumes, it also increases heating value.
It is also considered economical to remove nitrogen from low-BTU (British Transfer Unit) gas to either allow for liquefaction or to avoid unnecessary flaring and associated air pollution.
Gas with low heating value needs to be treated before it can be fed into the grid with the required Wobbe index. This is especially important for enhanced oil recovery, where nitrogen is used as a displacement gas and gets dissolved in the oil and associated natural gas.
Our portfolio for nitrogen rejection from natural gas includes single columns, single partitioned columns, double columns, and double columns with enrichment processes. We offer configurations tailored to the individual composition of the gas with respect to nitrogen content and other impurities, which could solidify in the cryogenic process.
Nitrogen removal is typically combined with the recovery of helium if it is also present. High-purity helium is obtained by the combination of cryogenic and pressure swing adsorption process steps.
Building on the know-how we have gained from several NRU plants built over the years, we deliver a broad portfolio of proprietary technologies for optimum recovery results.