Application Note

Carbon Dioxide (CO2) Measurement In Natural Gas

Emerson offers Rosemount gas analyzer technology to provide on-line analysis of CO2 in natural gas. The CO2 concentration is limited by quality standards specified by the major pipeline transmission and distribution companies. If CO2 concentrations are too high, removal techniques like amine washer, polymeric membrane usage, or pressure swing absorption (PSA) are applied.

Natural gas mainly consist of methane (CH4 70-90 %). Other components are ethane (C2H6), propane (C3H8), butane (C4H10) and higher hydrocarbons (up to 20 %). Carbon dioxide (CO2) can go from several ppm up to 8 %. Further components are nitrogen (N2), hydrogen sulfide (H2S) and noble gases as helium (He), argon (Ar), and neon (Ne).

Pipeline transmission legislation sets limits for the CO2 content of natural gas. Therefore, CO2 has to be measured and, if necessary, reduced by technical processes.