Simultaneous hydrogen sulfide /carbon dioxide removal and methane recovery from landfill gas by multi panel bubble lift column reactor using liquid phase catalyst

摘要

Simultaneous hydrogen sulfide and carbon dioxide removal for the methane recovery process has been developed on the pilot plant scale to provide an isothermal, low operating cost method for carrying out the simultaneous removal in landfill gas by liquid phase catalyst. Methane purification and carbon dioxide stripping by multi panel bubble lift column reactor using Fe-EDTA was conducted for evaluate optimum conditions for landfill gas. Reaction rate for H2S oxidation to elemental sulfur, CO2-stripping and absorption rate, pH change of solution CO2-stripping and methane recovery rate according to varied inflow air, and flow pattern with solution circulation rate were performed with pilot scale reactor. The experimental results are suggested for the optimum condition based on the gas inflow rate, bed expansion and reactor aspect ratio. From the results of RTD analysis for auto circulation bubble lift column reactor, it was known that the 40 mm of over flow liquid height and 1.5 L/min of air flow rate gave the fastest circulating speed of liquid in reactor. Circulation tile increase as the inlet gas rate increase in the range of 200 sec to 25 sec and increasing rate depends on the over flow height at the first panel. H2S was removed from 70 to 0.24 mg/L by 200L multi panel bubble lift column reactor containing 1500 mg/L Fe-EDTA at 1.5L/min input gas rate. CH4 concentrated up to 70% CH4 from 50% initial concentration of CH4 mainly owe to reaction pathway as follows; 2HS - + HCO3 →2S CO2 + 3HO -