Investigation of low-cost PM-sensors regarding the suitability for emission measurement for pulse-jet cleaned filters
FILTECH 2019 - The Filtration Event
P. Bächler, J. Meyer, A. Dittler
In the context of PM-immission measurement, cheap and compact low-cost PM- sensors have been established for fine dust monitoring of particle mass concentrations with high temporal and spatial resolution. The accuracy of these sensors is subject to many environmental influences, such as varying aerosol properties, particle concentration or relative humidity .
Another possible application for low-cost PM-sensors is emission measurement for gas cleaning devices, e.g. pulse-jet cleaned filters. In existing plants, the emission is typically measured at the end of the pipe and smaller plants sometimes do not even have any form of emission monitoring. Equipping individual filter bags with low-cost measurement equipment could offer insights into the internal emission behavior of filter houses and improve process monitoring. The suitability of the sensors for emission measurement is subject to research and the topic of this study. Filtration tests with two different filter media were carried out, where the emissions were measured with two different low-cost sensors. The test rig and procedure of the filtration tests are based on ISO11057. Out of a wide range of different sensors, the OPC-N3 from the supplier Alphasense and PMS7003 from the supplier Plantower were selected for evaluation in this study. A Promo 2000® in combination with a Welas 2100® sensor from the supplier Palas® serves as the reference device during the experiments.
The low-cost sensors and the reference show similar trends regarding the detected emission during filter aging and the ∆p-controlled filtration process. Both sensors are able to describe qualitatively the typical emission peak after pulse-jet cleaning of the filter medium. Considering the potential for quantitative information of low-cost sensors, reduced peak concentrations are detected after the filter aging step, indicating a lower mass based emission. Additionally, the emissions detected with a membrane filter medium are much lower than the emissions detected from a regular needle felt so that different emission levels can be identified by the low-cost sensors. This is also visible in a leakage experiment, where the low-cost sensors successfully detect an increase in particle concentration after damaging a membrane filter medium.