Biogas is a renewable energy source suitable for powering combustion engines, hence cutting down the need for coal, crude oil, and natural gas. Operators harvest it from liquid and solid waste streams, which are increasingly composed of siloxanes found in many industrial and household products. Engine manufacturers require maximum siloxane concentration in biogas to ensure efficient engine operation. In this article, we will explore the various biogas cleaning technologies for optimum siloxane removal.
What are Siloxanes?
Silicon, oxygen, and alkane make up the word ‘siloxane.’ As a family of organic compounds, Siloxanes are composed of linear or cyclic chains of silicon, oxygen, and methyl groups. They occur in a range of industrial and residential products, including water repellents, deodorants, cosmetics, food additives, toothpaste, windshield coatings, and biogas. Since biogas is produced from solid and liquid environmental waste, siloxanes are one of its major pollutants, causing several issues in its utilization. Although they are manmade, Siloxanes must be effectively removed from biogas to ensure durable and cost-effective biogas utilization.
Sources of Siloxanes
Biogas can be produced from uncontrolled and controlled systems. Uncontrolled systems include landfills and marshlands, while controlled systems include wastewater treatment plants (WWTP) and anaerobic digestion plants. These biogas sources have high siloxane contamination, resulting from waste from industries and households.
With landfill biogas, siloxane contamination results from high levels of organosilicon-containing wastes that are deposited in landfills through garbage collection. These wastes include paper coatings, textiles, cleaners, cosmetics, and deodorant containers. It’s important to note that landfill siloxane concentration differs from landfill biogas siloxane concentration because of climate conditions and landfill age, amongst other factors.
Silicon-containing substances are present in personal care products like aftershaves, creams, etc. These are principal sources of siloxane to wastewater, which are then channeled to the controlled systems. These systems have a higher siloxane concentration in anaerobic digestion plants biogas than in WWTPs biogas. Resulting from the strong hydrophobicity of siloxanes, extracellular polymeric substances (EPS) adsorb most of them in WWTPs, losing the rest to the atmosphere via volatilization. More siloxane content is present in biogas manufactured from the anaerobic digestion process.
Effects of Siloxanes in Biogas
Biogas serves as a fuel for engines, fuel cells, boilers, turbines, etc. They can cause adverse effects to these types of machinery if they contain a high concentration of siloxanes. Siloxane molecules break down into silicon and oxygen during combustion, which combines with additional elements to form silica, silicates, and other problematic compounds. These compounds settle in the combustion chamber, valve faces, and cylinder heads, causing various forms of wear and tear of these engine parts. The maximum permissible silicone concentration for engines is 5mg/Nm3. Biogas with high silicone concentrations can cause severe damage to biogas turbines and high maintenance costs.
Purpose of Removing Siloxane from Biogas
Siloxane removal from biogas is crucial for the consistent efficiency of regularly used machinery. Engine designers and manufacturers require a certain siloxane concentration limit in biogas to ensure hitch-free engine operations. Here are a few reasons you must remove siloxane from biogas:
- To ensure equipment and machines are operated optimally.
To foster the longevity of machines used for compr
DXP Enterprises Inc. published this content on 25 June 2021 and is solely responsible for the information contained therein. Distributed by Public, unedited and unaltered, on 25 June 2021 18:30:05 UTC.