Measuring concentration and size of fly ash particles from the clean gas side of a pressurised pulverised coal combustion (PPCC) test facility: appliance of a novel scattered light particle sizer
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Sixteen years ago, a joint research project 'Druckkohlenstaubfeuerung' (DKSF, pressurized pulverized coal combustion) was commenced, the aim of which was the development of a hard coa! fired power plant utilizing a combined gas and steam turbine cycle for a significantly increased efficiency (>>50%). A trial plant was erected in Dorsten, Germany, primarily to deal with gas cleaning and material related problems. One of the most significant tasks, which had to be solved at this DKSF trial plant is the separation of the fly ash at operating conditions, meaning at gas temperatures of 1400 deg C and a pressure of (up to) 16 bar. For this purpose, a multi-stage gas cleaning apparatus was developed at the Dorsten site, which uses an (electrically enhanced) arrangement of several mechanical separation devices (e.g. cyclones, granular bed filters etc.). The characterization of the separation device as well as the verification of the evolutionary improvement of the gas cleaning step called for a fast on-line measurement technique with a low detection limit to reliably check the emissions even at the required limits of less than 3 mg/m3STP and particle sizes below 3 microns. Assuming these values, an estimation leads - for an average particle size of 1 micron - to number concentrations of 103 to 104 particles/cm3. For that reason, a scattered light particle sizer was developed at the Institute of Mechanical Process Engineering and Mechanics at the University of Karlsruhe, which at the moment is able to measure at pressures up to 16 bar and temperatures up to 450 deg C. Measurements with this device have been performed at the DKSF test site for the last 2 years They show the applicability of the technique as well as the ability to identify any improvements required to the separation performance of the gas cleaning devices. Up to now, it can be stated that the cleaning efficiency requirements, at least for the fly ash detectable within the measurement range, are fully met, including a significant safety margin to compensate for possible measurement errors (related to mass calibration and dilution errors).
Measuring concentration and size of fly ash particles from the clean gas side of a pressurised pulverised coal combustion (PPCC) test facility: appliance of a novel scattered light particle sizer
Additional title:
Messung der Konzentration und der Größe der Flugascheteilchen auf der Reingasseite einer Prüfanlage für die Druckkohlenstaubfeuerung: Einrichtung eines neuartigen Streulicht-Partikelsiebklassierers