Siloxane Removal For Bio-gas
Siloxanes are man made compounds that contain silicon, oxygen and metal. Siloxanes are used to manufacture personal hygiene, healthcare, and industrial products. As a consequence of their widespread use, siloxanes can be found in waste water and in solid waste deposited in landfills.
Evidence of siloxanes in biogas is found in the form of a white powder and gas turbine hot section components. It’s a light coating on various types of heat exchangers, deposits on combustion services, in reciprocating engines, and as a light coating on post combustion catalysts.
The white powder is primarily silicon dioxide a product of siloxane combustion. Microturbine and catalyst failures have brought great focus on siloxanes and the manufacturers of these combustion components look to Hengye to provide selective media that can be used to remove siloxane.
Renewable Energy: Methane Collected from Landfills
Landfill gases are a large contributor to the annual emissions of greenhouse gases in the United States and around the globe. The most detrimental of the greenhouse gas released from landfills is methane, which is a useful renewable fuel if it can be collected and cleaned. Methane, sometimes referred to as natural gas, is commonly produced in natural processes such as digestion. Methane forms as a byproduct, produced by landfills, because these environments function like a giant stomach as waste is decomposed. Aside from collecting the gas to protect the environment, methane is a valuable gas that can be used in place of other fuels such as propane and butane. Methane is often burned to create other types of energy such as electricity.
How it Works
Specialized equipment has been developed over the years to collect methane from existing or new build landfills. Wells are drilled deep into the earth where waste has been buried to collect the methane that is being produced underground. The gas is vented into collection manifolds and pipes, where it can be transferred above ground and processed. The gas is cleaned by methods of filtration that dehydrate and purify the gas, which allows it to be transported and used in a clean manner. Once being cleaned, the gas is generally considered safe for burning and for use in engines.
Engine Breakdown Prevention
Removing siloxane is an important step in cleaning methane gases for use as fuel since siloxane is a form of crystalline silica that will essentially turn into glass when burned or combusted. The collection of combusted siloxanes inside of engine components can cause the buildup of heat, water, and other contaminants that can cause corrosion, leading to problems in the engine. Engine breakdown will cause an increase in maintenance costs as they can occur more frequently and with more damage than what should be expected. If the engine isn’t properly maintained, the engine could eventually breakdown and lead to total engine failure.
Silica Gel Removes Siloxanes to Protect Your Equipment
Hengye Inc. offers a suite of products that are suitable for removing siloxane from methane streams, collected from landfill gas. Silica gel is a common, reusable filter, that can clean methane by removing siloxanes and other contaminants, and help support successful equipment operations. Hengye silica gel appears as white beads, measuring 2-5mm in diameter, and designed specifically to remove contaminants that cause engine damage.
When to Replace Your Silica Gel with Fresh Material
Hengye silica gel can remove siloxanes to concentrations well below 1% when it is fresh, and although it’s better to replace filtration media often to protect equipment, concentrations as high as 40% can be considered acceptable in some operations. Users should always review owner manuals and follow manufacturer recommendations to determine appropriate concentrations of siloxane. Used silica gel can typically be disposed of in landfills and waste facilities as this material functions as a filter and cleans the environment, be sure to check with regional and local law requirements before deciding what to do with used material. Although silica gel can be regenerated, it often is not considered cost effective given the reasonable price of silica gel, the cost of regeneration, and the loss of efficiency of silica gel after regeneration.
Siloxane Removal Products