Simultaneously removes carbon dioxide (CO2) and water from contaminated natural gas. Feedstocks include coalbed methane and natural gas. Water-saturated feeds and CO2 levels of 3% to 40% can be treated. Product is pipeline-quality natural gas with characteristic CO2 levels of less than 2%. The process uses a specialty adsorbent for CO2 removal in a patent-pending, proprietary, pressure swing adsorption (PSA) system.
Water-saturated feed, at pressure levels between 100 psig and 800 psig, is routed through a series of adsorber vessels. One or more vessels are removing the water and CO2 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 water and CO2, the spent vessel is removed and replaced with a regenerated one. It is depressurized and produces a low-pressure, methanerich stream for compression/recycle to the feed and a low-pressure fuel stream containing CO2 to be rejected. To maximize adsorbent capacity, impurities are removed through a single-stage vacuum blower.
If the feed contains C3+ components in large quantities an NGL recovery section can be added to produce a mixed NGL product containing these components at high recovery rates. The system is flexible for a wide range of CO2 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 typical total installed cost is $0.30/Mft3 of feed processed. This cost decreases to less than $0.15/Mft3 for a 10-MMscfd design. Modular construction allows low-cost installation and equipment relocation flexibility.
Licensor: Engelhard Corp.