Decarbonization of simulated biogas with microchannel mixer by pressurized water scrubbing

Abstract

Pressurized water scrubbing is an environmentally friendly technology for the decarbonization of biogas. However, the key bottlenecks such as low efficiency, high cost of water consumption and secondary CO2 emission by water absorption and desorption in the process of decarbonization are still necessary to be solved. This study focused on improve the mass transfer effect by introduce finger-crossed microchannel in the process of simulated biogas decarbonization using pressurized water scrubbing. The simulated biogas was mixed with pressurized water in the finger-crossed microchannel, and the gas-water mixture was continuously separated in the gas-water separation tank. The effects of pressure (26–30 bar), temperature (5–30 °C), gas-water ratio (5:1–12:1), liquid volumetric flowrate (5–10 mL/min), and other factors on the decarbonization were investigated. The overall mass transfer coefficient based on the liquid phase and the CO2 flux were also calculated and analyzed. The decarbonization parameters were optimized using the response surface methodology as follows: temperature 20 °C, pressure 29/27 bar, gas-water ratio 10:1, liquid volumetric flowrate 5 mL/min. The process remained stable, achieving 98 % removal of CO2 under optimal conditions. Furthermore, the CO2 concentration in the purified gas was maintained below 3 %. Additionally, a significant number of micro-nano bubbles were observed in the absorption water obtained through this mixer, and the releasing of CO2 from the water lasted 5 days. These results indicated the excellent decarbonization performance of the finger-crossed microchannel in pressurized water scrubbing and potential application value of new ways of CO2 absorption water without desorption.