Study On Powder Concentration Measurement Technology

With the acceleration of Chinese industrialization, industrial dust emissions also increase day by day, the environmental problems caused by the dust pollution are more and more serious. In order to achieve the purpose of environmental protection, it’s necessary to monitor the concentration of dust particles emitted. At present, there are a lot of methods to measure powder concentration. They can be generally classified in two kinds, one is the method that based on sampling, and the other is the method that based on the non-sampling. With the prompt development of science and technology, the advantage of the opto-electric(OE) method which does not need sample has stood out.Nowadays the extinction method of the OE measurement, which is based on Mie theory, has been generally applied. Though it effects well when powder concentration is low, it cannot get a good measurement result when the concentration is high. To solve this problem, it proposes to use the method based on Lambert-Beer law of extinction in this paper after researching and analysis. This method can work effectively when the concentration is high. Based on the extinction theory, we have got the calculation formula of the powder concentration, in this paper it has showed the whole scheme about using light transmission method to measure, and has proposed to use the double beam differential detection principle to reduce requirements of the light source’s stability. Using the method of computer simulation, we have analyzed and researched the key parameter of the measurement system. According to the simulation results, we have studied how to choose the wave length of the light source and the absorbing layer thickness and how they effect the concentration measurement results. Besides, in this paper, there are wiring designs for measuring each module, and the selection of the module of key devices are also studied and compared.At last, the smoke test has been conducted by using the light transmission method to measure the concentration in this paper, and through this test, we get the changing rule of the voltage signal corresponding to the transmitted intensity, which based on the same change of the powder concentration and the different wavelength and different absorption layer thickness, The experimental phenomena is consistent with the theoretical analysis. Besides, the powder test has been conducted, and partial result has also been listed. The result showed that the concentration measurement discussed in this paper is feasible. And I believe that it will be applied widely.