Chapter 10 Nitrogen Rejection Unit Gas Processing I NGT 140 Chapter 10 Nitrogen Rejection Unit “This product was funded by a grant awarded by the U.S. Department of Labor’s Employment and Training Administration. The product was created by the grantee and does not necessarily reflect the official position of the U.S. Department of Labor. The Department of Labor makes no guarantees, warranties, or assurances of any kind, express or implied, with respect to such information, including any information on linked sites and including, but not limited to, accuracy of the information or its completeness, timeliness, usefulness, adequacy, continued availability, or ownership.” Unless otherwise specified, this work by ShaleNET U.S. is licensed under a Creative Commons Attribution 4.0 International License.

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Nitrogen Rejection Is a necessary process in maintaining a desired Btu value for sales gas and pipeline specifications. Adding nitrogen lowers the Btu value Removing nitrogen raises the Btu value Nitrogen is removed from feed gas at low temperatures in a nitrogen rejection unit (NRU).

Types of Nitrogen Rejection Units Pressure swing adsorption A process using a molecular sieve and alternate high and low pressure swings. (moderate recovery) Cryogenic absorption Uses chilled hydrocarbon oil to absorb the bulk of the methane and achieve a separation of nitrogen from natural gas. (widely used) Membranes Membranes are used to selectively permeate methane and reject nitrogen in the gas stream. (low to moderate recovery) Cryogenic distillation Done through condensation and distillation at cryogenic temperatures. (used for large scale applications and is commonly used due to its efficiency and reliablility)