Remove nitrogen (N2) from contaminated natural gas. Feedstocks include N2 contamination from 5% to 30%. Product is pipeline quality natural gas with typical N2 levels of 3% to 4% using the Molecular Gate process and a patented proprietary adsorbent in a pressure swing adsorption (PSA) system.
Natural gas at pressure levels between 100 psig and 800 psig is routed through a series of adsorber vessels. One or more vessels remove N2, while pipeline-quality natural gas flows through the adsorbent bed at essentially feed pressure. Typically, between three and eight adsorber vessels are used. When the adsorbent is saturated with N2, the spent vessel is removed and replaced with a regenerated one. It is depressurized and produces a low-pressure, methane-rich stream for compression/recycle to the feed and a low-pressure fuel stream containing N2 to be rejected. To maximize adsorbent capacity, N2 is typically removed through a single-stage vacuum blower. The process is based on an adsorbent that is size selective and allows smaller N2 molecules to fit in adsorbent pores, while the larger methane molecule is unaffected. Carbon dioxide is also completely removed with the N2 and oxygen is removed at N2 levels. The system is flexible for a wide range of N2 concentrations and has turndown capability to 30%. Modular construction facilitates installation.
Economics: The technology can be cost-effectively applied to a wide range of flowrates. A small, 2-MMscfd unit’s total installed cost is $0.50/thousand ft3 of feed processed. This is decreased to less than $0.30/thousand ft3 for a 10-million scfd design. Modular construction allows low-cost installation and equipment relocation flexibility.
Licensor: Engelhard Corp.