Oxygen for Hydrogen Sulfide Removal from Biogas

Rising energy costs and the green revolution have increased the demand for bio methane from biogas. Biogas is an eco-friendly fuel, and renewable natural gas (RNG) is preferred to help reduce pollution and carbon footprints. To produce bio methane, carbon dioxide (CO2), hydrogen sulfide (H2S), and water must be removed from biogas. Oxygen (O2) generators can effectively remove hydrogen sulfide (H2S) through a multi-step process. These machines add oxygen to a digester that breaks down waste materials and work best when used with other technologies for improved results.

Introduction to Biogas and Bio methane

Biogas is produced from various types of waste, including agricultural, organic, and industrial waste. It forms through a process called anaerobic digestion, where waste decomposes without oxygen. This waste contains high levels of sulfur compounds, including H2S, which can harm the environment. Therefore, it’s crucial to separate H2S and convert biogas into bio methane.

The process to remove hydrogen sulfide from biogas typically involves a digester, biogas blower, low-pressure refrigerant dryer, biogas compression, and CO2 removal technologies like PSA or membrane systems. This process can also recover CO2, providing additional revenue for biogas plants. When oxygen is added in small amounts to the digester, it helps eliminate H2S. In the digester, waste breaks down and transforms into gas. Bio methane is the cleaned version of biogas and is similar to natural gas.

Why Oxygen?

Several methods exist for removing H2S from biogas, including oxygen dosing and ferric dosing. Oxygen dosing generally requires less maintenance and is more cost-effective. In contrast, ferric dosing needs regular replenishment of ferric salt and replacement of activated carbon filters, which adds to costs. Other methods include iron hydroxide scrubbing, sodium hydroxide (NaOH) scrubbing, and iron oxide pellets. The first two involve chemical processes that require careful waste management and regeneration. Water scrubbing uses available water but is ineffective for biogas with high H2S levels, and H2S-saturated water must be disposed of properly.

Oxygen: A Low-Cost Alternative

Generating oxygen is an affordable way to reduce H2S levels. When oxygen is added, it reacts with H2S, converting it into sulfur and water. It’s crucial to use the right amount of oxygen, ideally between 0.3% and 3%, with 1% being optimal for the best results in biogas. Care must be taken with oxygen purity; low purity can introduce too much nitrogen (N2), while excessively pure oxygen can pose safety risks.

On-Site Oxygen Generators

?For optimal oxygen supply, having an on-site oxygen generator is recommended. This equipment allows you to control purity levels, reducing risks related to oxygen quality. On-site generators also save transportation costs.

Conclusion

Biogas and bio methane represent the future for many nations, offering industrial uses that harm the environment the least. To convert biogas into bio methane cost-effectively, oxygen emerges as a key solution. Concerns about oxygen purity and production can be addressed by implementing an in-house oxygen generation plant.