Siloxane removal with gas permeation membranes

Abstract

The digestion of organic material in waste disposal sites, sewage treatment plants or fermenters leads to the production of low calorific value fuel gas, which can be used in combustion processes to generate electricity. However, corrosion and deposits on machinery and plant components, on the one hand, and relatively high emissions of particles and pollutant exhaust gases, on the other hand, make a preliminary gas cleaning step necessary. As one of many trace components fuel gases might include, siliconcontaining compounds, so-called siloxanes, have been identified as a serious problem. Upon combustion, silicates and micro-crystalline quartz are produced, leading to abrasion and deposits on the combustion unit, promoting mechanical wear and increased gas pollutant emissions. Plant engineers have reacted to this problem by conventional methods used in gas-cleaning technology, including siloxane removal by condensation, adsorption or gas scrubbing. All have their process-specific advantages and inconveniences. The IVT is studying gas separation membranes in combination with these conventional methods as a possible process to reduce siloxane and other trace component concentrations more effectively.