VOCs & Siloxanes
What are VOCs & Siloxanes?
While composed primarily of methane and carbon dioxide, biogas also contains a host of contaminants including moisture, hydrogen sulfide, and Volatile Organic Compounds (VOCs). All VOCs can be a health, safety or maintenance concern and need to be removed. The most problematic VOCs are called “siloxanes” which are a family of man-made organic compounds used in the manufacture of cosmetics, hygiene products, foods, and industrial coatings. As these products are used and disposed of, the siloxanes make their way into landfills, waste water and food waste.
As the material in a landfill or digester decomposes and generates biogas, the VOC and siloxane molecules enter the biogas stream as a vapor.
Why are they a problem?
In renewable natural gas (RNG) projects, the removal of VOC and siloxane vapors is critical to protect biogas upgrading equipment, and to meet the necessary gas quality specifications for pipeline injection. Pipeline operators have strict limits on VOCs and siloxanes as they can contaminate the pipeline and cause significant damage to downstream equipment.
In biogas to power generation or combined heat and power (CHP) projects, VOC and siloxane reduction is equally important. During combustion the siloxanes undergo a phase change from a vapor to a solid silicon dioxide powder. This abrasive powder adheres to all surfaces downstream of the point of combustion, reducing heat transfer, blocking flow and increasing wear. In engines or turbines, this build up quickly reduces efficiency and will eventually causes total equipment failure. Frequent overhauls to remove this build up can significantly increase project operating costs and downtime. In fuel cells, microturbines, or any project requiring the use of post combustion exhaust catalysts, siloxane vapor reduction is an absolute necessity to prevent rapid and complete failure of the technology.
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Fortunately, Willexa Energy's VOC & Siloxane Reduction Systems offer a cost effective, guaranteed way to remove siloxane and VOC vapors, protecting your assets, reducing operating costs and downtime, and maximizing project profitability.
Regeneration is the solution
One way to remove VOCs and siloxanes is to use a vessel (or a series of vessels) filled with non-regenerative activated carbon media. While this works well for small flows of relatively clean gas or in polishing applications, for high flows or heavily contaminated biogas the useful life of the carbon can be very short. The frequent media change outs can result in a high cost of replacement media, downtime, labor, vacuum truck services, and disposal. In many cases this can cost hundreds of thousands of dollars per year.
A Willexa Energy Regenerative VOC & Siloxane Reduction System is the answer. Our regenerative systems use a non-carbon based media that is regenerated in a fully automated and continuous cycle so it can be used over and over. This drastically reduces the frequency of media change outs, thereby drastically reducing ongoing consumable and operating costs.
Our engineers invented this technology and we have the longest and most successful history of any provider. Contact us today and let us show you how our innovative technology can improve the profitability of your biogas project.
