H2S Removal from Biogas Using KI-Impregnated Activated Carbon Adsorption for Power Generation in a Small Pig Farm

摘要

The typical H2S concentration found in biogas produced from pig manure ranges between as low as about 50 ppm to 10,000 ppm. Due to its contribution to SO2 emissions, safety concerns, corrosion, and odours, H2S must be removed prior to feeding into engines. In this study, the H2S removal unit was introduced to the biogas-to-power generation system in a small-sized pig farm. Adsorption using activated carbon granules impregnated with 2 % KI was used to keep H2S concentration below 100 ppm. The temperature of the adsorption columns was maintained at 50°C. The adsorption tests showed that more than 99 % of H2S in biogas could be removed by adsorbent. The adsorption capacity was 0.062 kg of H2S/ kg of adsorbent or 32 hours for 2 kg of fresh adsorbent. The economic assessment showed that the pay back period for investing the system without the H2S removal unit was 3.64 years, while the pay back period increased to 11.14 years with the H2S removal unit, which is much less attractive. However, the assessment did not take into account the environmental benefit and others such as utilisation of spent carbon for soil improvement or as fuel for heat.