Biogas / Biomethane Treatment

Biogas is commonly harvested from the decomposition of organic matter as source, which is rich in methane (CH4) and carbon dioxide (CO2) besides other contaminants such as hydrogen sulfide (H2S) and moisture. In the context of biogas power generation, the intricate balance of humidity becomes a crucial focal point. The substantial moisture content, in conjunction with the high content of hydrogen sulfide (H2S), takes center stage in influencing the efficiency and reliability of biogas power plants. This intricate interplay of elements significantly impacts operational performance, accelerates corrosive processes, and contributes to the deterioration of vital components such as gensets and boilers. boilers.

Our biogas treatment system includes a biogas desulfurization and dehumidification process. The purpose of this process is to remove unwanted substances from the biogas, such as Hydrogen sulfide (H2S), ammonia, particulate matter, moisture.

Biogas Desulfurization System :

When biogas is produced from anaerobic fermentation process, especially at medium to high temperatures, it carries a large amount of H2S. Due to the presence of a large amount of water vapor in the biogas, the water and H2S in the biogas act together to accelerate the corrosion and blockage of metal pipelines, valves, and flow meters. In addition, SO2 produced by the combustion of H2S combines with water vapor in the combustion products to form sulphurous acid, which corrodes the metal surface of equipment and pollutes the atmosphere, affecting health of plant operators. Therefore, before using biogas, it is necessary to remove the H2S in it.

There are several desulfurization we offer :

1. Dry desulfurization: Dry desulfurization refers to injecting dry desulfurizing agents such as iron oxide, calcium hydroxide, and sodium hydroxide into biogas, and converting H2S into sulfides or sulfur through chemical reactions to achieve the purpose of desulfurization. This method has the advantages of simple operation and low capital cost, but issues such as regeneration of dry desulfurizing agents and disposal of waste need to be addressed. It is generally suitable for biogas with low H2S concentration and low gas volume.

2. Wet desulfurization: Wet desulfurization refers to passing biogas through a liquid absorbent, such as an alkaline solution or an oxidizing solution, to convert H2S into sulfate ions or other forms of sulfur compounds. This method has high desulfurization efficiency, but the cost is relatively high, and wastewater treatment is needed.

3. Biological desulfurization: Biological desulfurization utilizes specific microorganisms to adsorb and convert H2S in biogas into sulfate ions and other forms of sulfur. This method has the advantages of simple operation, high desulfurization efficiency, low operating and maintenance cost and no waste generation. 

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Biogas Dehumidification System

The biogas collected from the anaerobic digestor is often in a saturated or near-saturated state, with a water vapor content of about 1 to 4% (volume ratio). The presence of these water vapors will have adverse effects on the subsequent resource utilization process or equipment, so removal and purification are required.

The importance of controlled humidity for gensets and boilers:

Maintaining controlled humidity levels is particularly essential for two critical components within biogas power plants:

1. Gensets: Gensets play a pivotal role in converting biogas into electricity. Uncontrolled humidity levels can disrupt the combustion process, leading to irregular energy generation and operational inefficiencies.

2. Boilers: Boilers are integral to harnessing the energy potential of biogas. Elevated humidity can contribute to corrosion, degradation of components, and reduced operational lifespan.

Effects of uncontrolled humidity: In the context of gensets and boilers in biogas power plants, uncontrolled humidity levels beyond a critical threshold, typically 40% relative humidity (RH), can result in various adverse outcomes:

1. Operational Disruption: High moisture levels can disrupt the energy conversion process, resulting in fluctuations in electricity generation and overall inefficiencies.

2. Corrosion and Deterioration: Excess humidity accelerates corrosion, causing degradation of genset and boiler components, ultimately shortening their operational lifespan.

3. Energy Loss: Inefficient energy conversion due to humidity-related challenges can lead to decreased energy output, directly affecting the overall power plant efficiency.

We offer cooling dehumidification solution to reduce the moisture content of biogas by lower its temperature to its dew point temperature and causing the water vapor in the biogas to condense out and the heat of condensation is carried away by the refrigeration equipment. 

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