1. Chapter 10 Nitrogen Rejection Unit
Gas Processing I NGT 140
Chapter 10
Nitrogen Rejection Unit
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2. Ch 3
Ch 5
Ch 2
Ch 7 & 8
Ch 10
Ch 4
Ch 6
Ch 9
Ch 2
Ch 9

3. 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).

4. 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)