Introduction
It is estimated that 25% of the United States natural gas reserves contain unacceptably large quantities of nitrogen. Nitrogen is inert and lowers the BTU value of natural gas. It also takes up capacity in pipelines that could be used for valuable methane. Thus, nitrogen needs to be rejected from the gas through a Nitrogen Rejection Unit NRU. Typically, the feed to nitrogen rejection unit comes from the top of the DeMethanizer column of a cryogenic NGL recovery unit.
