No abstract

In light of climate change and the fact that surface transportation heavily relies on internal combustion engines, many different alternatives to gasoline have been proposed.

Thus far, the elemental characterization of particles in energy conversion process gases and emissions has conventionally either been performed offline or information on the particle size has not been available. Such processes include combustion in engines or thermal treatments of renewable and fossil fuels for heat and power generation. One established physical aerosol measurement instrument is the scanning mobility particle sizer (SMPS), providing size distribution and concentration of gas-borne particles online, with temporal resolutions of a few minutes or even less. However, a far greater wealth of information can be gained by combining the opportunities of the SMPS with those of an inductively coupled plasma mass spectrometer (ICPMS), which enables the determination of the elemental composition of an introduced sample with low detection limits and a wide dynamic measuring range, and those of a rotating disk diluter (RDD), used as a sample introduction interface, making the setup independent of a defined aerosol source flow. We have recently presented such an instrumental setup, which is used now for online measurements on particulate sodium, chlorine, potassium, and copper, in aerosols emitted by differently impregnated wood samples, heated in a thermogravimetric analyzer (TGA). The TGA allows controlling the temperature, oxygen content, and gas flows in the furnace and is used for generating model aerosols to study the influence of different fuel treatments on the emissions during the combustion process. The ability of RDD–SMPS–ICPMS to discriminate between several elements contained in specific particle size classes between 13 and 340 nm at different times in the aerosol emitted by a thermal process is demonstrated.

In biomass gasification processes, the formation and handling of tars are of major concern. Robust and versatile analytical tools are needed to on-line monitor tar compound concentrations in process gases from lab-to industrial scale. This study addresses the development and application of an on-line UV-Vis method, based on a liquid quench sampling system. The high sensitivity of this method allows to detect UV-Vis active tar compounds in the low ppmv region. Recorded spectra from the liquid phase were analyzed for their tar composition by means of a classical least squares (CLS) and partial least squares (PLS) approach. The developed method was applied to two case studies, involving a lab-scale tar reformer and a pilot-scale gas scrubber. Quantification results in gases with limited complexity in tar composition showed good agreement with off-line reference methods (GC-FID). The case studies show that the developed method is a rapid, sensitive tool that can be applied for qualitative process monitoring with the added benefit of quantification in gases with a limited number of tar compounds.