Modeling the Water Scrubbing Process and Energy Requirements for CO₂ Capture to Upgrade Biogas to Biomethane

Abstract

Water scrubbing is the most widely used technology for removing CO 2 from biogas and landfill gas. This work developed a rate-based mass transfer model of the CO 2 -water system for upgrading biogas in a packed bed absorption column. The simulated results showed good agreement with both a pilot-scale plant operating at 10 bar, and a large-scale biogas upgrading plant operating at atmospheric pressure. The calculated energy requirement for the absorption column to upgrade biogas to 98% CH 4 (0.23 kW h N m 3 , or 4.2 % of the input biogas) is a significantly closer approximation to the measured value (0.26 kW h N m 3 , or 4.8 % of the input biogas) than has previously been reported in the literature. The model allows for improved design of CO 2 capture and biogas upgrading operations, and can also be a useful tool for more detailed cost-benefit analysis of the technology.

Power requirements of biogas upgrading by water scrubbing and biomethane compression: Comparative analysis of various plant configurations

“…Finally, in Fig. 7 of [41] the results for a smaller plant (60 Nm 3 /h) are presented. It is shown that minimal power requirement is achieved at 0.8 MPa -0.32 kWh/Nm 3 raw biogas, which is roughly the same as our predictions.…”

Production and Purification of Biogas; A Research

“…Three retrofits were used and tested separately using gas engine-First system which captures CO₂ from crude biogas by chemical absorption process Second system which captures CO₂ after combustion of biogas by chemical absorption process and third system which captures CO₂ after combustion of raw biogas with pure O₂ instead of air (oxy-fuel combustion process). Moreover, after the comparison we have found that first system provides the better results compare with the other two systems [11].…”

The Technical and Energetic Challenges of Separating (Photo)Electrochemical Carbon Dioxide Reduction Products

“…Known as "water scrubbing," the higher solubility of CO 2 relative to CH 4 allows it to preferentially dissolve in water, effecting separation. The required energy input needed to produce 98 wt% CH 4 from biogas (containing ~50% CH 4 and ~50% CO 2 ) in a 10 bar pilot-scale plant has f = ~5% (Nock et al, 2014). Similarly, poly(ethylene glycol) has been used to remove CO 2 from biogas, and is estimated to require f = 7-9% to regenerate (Luostarinen et al, 2011).…”