Economically effective methods for desulfurizing industrial biogas

It seems that iron salts can be used as desulfurizers; as for how to do it, I’m not quite sure.

We have extensive experience in the biological treatment of waste gases; biogas mainly contains hydrogen sulfide, which can be easily removed using biological filtration. But it’s uncertain whether the methane content will be affected, as no studies have been conducted, so no conclusions can be drawn. There is a foreign-funded company; we are conducting preliminary tests, and I’ll let you know once we have results

Biogas has a low oxygen content; biological treatment is required, which necessitates the introduction of air.

Iron hydroxide method: Iron shavings and wet wood chips are thoroughly mixed, and 0.5% calcium oxide is added to create a desulfurization agent, with a humidity level of 30–40%. Hydrogen sulfide is removed by reacting with a desulfurization agent, and the regenerated iron hydroxide can be reused. The reactions are as follows: 2Fe(OH)₃ + 3HS⁻ → FeS + 6H₂O; 2FeS + 6H₂O + 3O⁻ → 4Fe(OH)₃ + 6S. This method offers high desulfurization efficiency and is suitable for purifying gases with low hydrogen sulfide content; however, the desulfurizing agent must be regenerated and replaced regularly.

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1. Washing method: At a temperature of 20°C and a pressure of 1 atmosphere, each cubic meter of water can absorb 2.9 m3 of hydrogen sulfide. This method is economical for dealing with large amounts of hydrogen sulfide gas from mines, but the removal efficiency is generally only 60 to 85%; the biogas resulting from this treatment still does not meet the requirements specified for city gas. 2. Alkali washing method: Desulfurization is achieved by spraying nitrogen water, dilute alkaline solutions, or ethanolamine, etc. This process requires power; since large amounts of alkaline solution are used to remove CO2, the alkaline solution is depleted, and additional dedicated personnel are needed. Although the desulfurization effect is good, the cost is high, increasing the cost of biogas significantly. This method is suitable for feed gas requiring a very low sulfur content. It is not very suitable for large amounts of biogas used as fuel. 3. Modified A·D·A method (i.e., modified onion-packed sodium dithiosulfate method); this method features high desulfurization efficiency, wide applicability under various process conditions, and the ability to recover sulfur as well. However, the equipment is relatively complex, and strict operating requirements apply. A·D·A is worth 600 per ton. . Yuan is relatively expensive; it is more cost-effective for handling volumes of over 500,000 m3 per day. For me! With only 40,000 cubic meters of biogas produced per day, the equipment investment and operating costs are too high; it also requires specialized personnel for management, so it’s not suitable. 4. Dry iron oxide method: The desulfurizing agent used in this method is made from scrap pig iron from mechanical processing plants and sawdust from wood processing plants. It is inexpensive, requires simple equipment, has a long operation time, is easy to regenerate, results in low desulfurization costs, and can achieve the required desulfurization levels. From the above comparisons, it can be seen that using the dry oxidation of iron method is a suitable choice for desulfurization in order to produce 40,000 cubic meters of biogas per day at our factory.

This post was last edited by 42936803 on 2009-8-4 08:46. There is a biogas power generation company in Yixing, Jiangsu, which uses DDS for desulfurization. The volume of gas produced per hour is around 200 cubic meters, with a sulfur content of approximately 15–20 grams. The sulfur content at the output end is zero. After spending 7,000 yuan on the equipment needed for automatic chemical dosing, it has been about 2 months since then, and no additional chemicals have been added. It can be said that the effect is good and the consumption is low