| The dust generator used for calibration and validation of the dust monitor which is based on the theory of particle group light scattering, its internal spatial distribution of dust and stability directly affect the reliability of the results of the calibration and validation of the dust monitor. So we discussed the online monitoring issues of its internal spatial distribution of dust in this paper, and introduced a measuring method of the spatial distribution of dust concentration which is based on the CCD image processing system, then we carried out theoretical and experimental research.Theoretically, we established a measuring model which is based on the Mie scattering theory and Beer-lambert attenuation law, and obtained the relationship between the received light intensity of pixels and the dust concentration at pixels conjugate point. In order to verify the accuracy of the model, we established a Monte Carlo model of photon transport in the dust medium. Compared with the theoretical calculation results, the simulation results have a good consistency.Experimentally, we built a measuring system of the spatial distribution of dust concentration which is based on the CCD image processing system, then given the calibration method of the experimental device and a typical temporal and spatial distribution of the smoke dust. We introduced the mean and standard deviation to measure the change of the spatial distribution of dust concentration inside the dust generator. By contrast test with the WL1001B dust monitor, we calculated the dust mass concentration measuring range of the CCD image system, which is from 1.394 milligram per cubic meter to 17 gram per cubic meter and in line with the concentration range of the dust generator, and the relative dust concentration accuracy is 0.39%.The research work in this paper has a certain reference value for the development of a new dust generator which comes with the monitoring function of the spatial distribution of dust. |
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