Abstract: A plurality of different layers of filter media are used to remove siloxanes from a gas stream. Based on an analysis of the specific gas stream to be filtered, a filter media having an average pore size enabling the preferential removal of a specific class of contaminants is selected for each different class of contaminants. The layers are arranged in sequential order such that contaminants having a higher molecular weight are preferentially removed by the first layers. Collectively, the layers define a segmented activity gradient that enables each class of contaminants present in the gas stream to be preferentially removed in a different layer, preventing removal competition between different classes of contaminants. Preferable adsorption media exhibit a relatively narrow range of pore sizes. Both inorganic adsorption media and carbon-based adsorption media exhibiting a relatively narrow range of pore sizes can be used.

Abstract: A plurality of different layers of filter media are used to remove siloxanes from a gas stream. Based on an analysis of the specific gas stream to be filtered, a filter media having an average pore size enabling the preferential removal of a specific class of contaminants is selected for each different class of contaminants. The layers are arranged in sequential order such that contaminants having a higher molecular weight are preferentially removed by the first layers. Collectively, the layers define a segmented activity gradient that enables each class of contaminants present in the gas stream to be preferentially removed in a different layer, preventing removal competition between different classes of contaminants. A polymorphous graphite is used as the filter media, because that material is available in a range of well-controlled pore sizes, as opposed to conventional activated carbon filter media, which generally exhibits poorly-controlled pore sizes.

Abstract: A process to purify biogases (i.e., landfill gas and municipal digester gas), to enable such biogases to be utilized to generate electricity and heat. Biogases from these sources generally include small amounts of organosilicons (which are particularly harmful to power generation equipment, and especially harmful to micro-turbines, reciprocating internal combustion engines, and large turbines), and halogenated chemical species (which can foul expensive emission catalysts). A fluidized media bed reactor is configured to concentrate offending organics, and is coupled with another reactor vessel configured to strip the offending organics off saturated media with a hot inert gas. The removed organics are further concentrated into an inert gas stream that is conveyed to a small flare for greater than 99% destruction. The energy required to strip the organics from the spent media, and to energize the flare, is generated by the combustion of a small quantity of the purified biogas.