Information Request

Victoria Brewster – Product Leader; Spectroscopic Solution

The generation of electricity from municipal digesters and land fill is of increasing interest, as the biogas can allow for a form of renewable energy. Organosilicon compounds often find their way into land-fill or digester gases as siloxanes. Siloxanes are low-level hazards to the atmosphere in terms of their emissions, however when they are combusted in gas engines the hard silica that is produced is very harsh to the moving parts of the gas engine. Ultimately this increase maintenance cost and gives a lower energy output, making the generation of power less efficient. With this ever-growing market, the need for analysis of the siloxane content of the biogas pre-generator is important. A land-fill gas plant operator can determine the amount of siloxane removal of the pre-combustion feed gas. This enables a more cost-effective cleaning system to be employed. They can also determine whether an existing clean-up system is operating effectivelyThere is currently no standard method for gaseous siloxane measurement and to date no on-line gas process monitoring system. The usual method of gas analysis has involved the extraction of a sample gas, via bag or cylinder, and analysis off-plant. Sampling losses of siloxanes inevitably occur, as the sample can be adsorbed on to the sample container wall. Protea has developed an analytical model for our atmosFIR FTIR gas analyser that allows speciation of siloxanes on-line. The full spectrum technique of FTIR also allows for the measurement of the main gas components, CH4 , CO2 , NH3 etc. providing real time, in-situ full gas composition analysis. In this paper we compare directly readings from a Protea FTIR with offline sampling methods. Comparisons have been made for siloxane calibration standards as well as real world gas data from both landfill and waste water.