Particulate removal is essential to protecting sensitive equipment downstream. A mesh gas filter with a pore size of 3 to 6 microns disperses the gas stream, causing any fine particulates to drop out.
Moisture removal is accomplished by utilizing a gas-to-liquid heat exchanger that is cooled by a remotely installed chilling system. The gas temperature is reduced below the dew point as it passes through the heat exchanger, causing moisture to precipitate.
Alternatively we can apply glycol dehydration to remove the water particles from the gas.
Even though the composition of biogas varies depending on the nature of the AD feedstock used, in general it contains moderate to high levels of hydrogen sulfide or siloxanes. Hydrogen sulfide levels below 300 ppm are typically not an issue for the desired end use of the biogas; however, local air regulations may necessitate its treatment. The wide variety of hydrogen sulfide removal systems can be grouped into three general categories:
- Media based
Siloxanes are chemical compounds made of silicon and oxygen and are found in a variety of products ranging from personal care (e.g., hair shampoo) to lubricants and paints. Consequently, siloxanes can be found in the wastewater from industries making these products.
Our main concern is the presence of siloxanes in waste biosolids from public treatment plants, due to the use of cosmetics. The Siloxanes must be removed from biogas to realize long-term economic benefits.
- The most frequently applied technologies are:
- Activated carbon adsorption
- Activated alumina absorption
- Synthetic resin absorption
- Absorption by selective liquids
- Membrane technology
As a result, the sampling and testing of biogas for siloxanes is an important step in biogas upgrading process.
Particulate and moisture removal and compression systems are typically packaged into a single skid since all biogas conditioning systems require them. Compression is generally required to meet the required pressure for use or transportation.
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