การศึกษาการกำจัดคาร์บอนไดออกไซด์ในแก๊สชีวภาพด้วยฟองแก๊สระดับไมครอน

Abstract

The objective of this research is to apply microbubble generator for biogas purification with water scrubber technique. The microbubble generator was generated the bubble by swirl flow and shear biogas with water to generate small bubble that float to the top of column. CO2 will be dissolved in the water and purified gas can get thought to the top. This study simulated biogas by mixing CO2 and air. The experimental conditions are 0.1 litre/min of gas flow rate, 5, 10, 15, 20, 25, 30 and 35 litre/min of gas flow rate. The experiment can be divided 4 parts. First part is study about water flow in the column. Second part is study about the size of gas bubble. Third part is study about dissolving of CO2 in the water. The last one is study about dissolving of biogas in the water. Flow characteristics was simulated with ANSYS Ver.15.0 (Fluent). The bubble size measurement was captured with microscope camera and the diameter of bubble was measured with image processing. The dissolved of CO2 concentration before cleaning was varied at 30%, 40% and 50% for all water flow rate. Gas was measured with biogas check with infuriate sensor for methane (CH4 0-100%) and carbon dioxide (CO2 0-100%). The value will be calculated for CO2 removal and CH4 enrichment. The biogas upgrading with microbubble generator. Gas for the experiment was collected form the biogas factory to find the CO2 removal, CH4 enrichment and energy consumption. For the result, the simulation shows swirl flow in the nuzzle from high water-flow rate at the inlet to nuzzle outlet with the highest velocity. The water flow pattern at the outlet is stream jet which separate to the side of column. The swirl flow area will increase from water flow rate. The high-water flow rate effect to the diameter of bubble size. The 35 liter/min water flow rate can generate the smallest bubble size with 50.44 μm. For the CO2 dissolving, the high-water flow rate and CO2 concentration before cleaning effect to high CO2 removal that 35 litre/min water flow rate can generate 89.2% for CO2 removal at 50% CO2 concentration and 15 min after experiment. The biogas upgrading, the high-water flow rate effect to biogas purification case from smaller bubble size which the 35 litre/min water flow rate is the best value for methane purifying. The CO2 removal is not significant to water flow rate. The 20 litre/min water flow rate is the best for the application because of lowest energy consumption and good efficiency.