Real-time Measurement System Of Pulverized Coal Concentration And Phase Distribution In Pneumatic Pipeline

The flow of the hot air and pulverized coal in the pneumatic conveyor was the typical gas-solid two phase flow which parameter have great difficulties to measure, pulverized coal concentration mostly belong to soft sensing field and that measuring result is influenced by the change of the following factors such as temperature, humidity, air pressure, pulverized coal types, continuous phase velocity and discrete phase distribution。 This paper proposed the design and experimental evaluation of a radiometric instrumentation system which was developed for measuring the volume concentration and phase distribution of pulverized coal in a pneumatic conveying pipeline to ensure the safety of the power boiler operation and economical efficiency. The system employed point y-ray source with180°plane angle of emergence source collimator, γ-ray source and collimator manufactured as a whole convex into the flow field, γ-ray detector multi-element independent each other annular arrayed out of the sensor conduct wall, and the entire conveying pipe cross-section is divided into several equal infinitesimal elements which gives sensing field homogeneity to overcome the impact of the inhomogeneity and instability of pulverized coal distribution. Choose the thickness of lead plates used to shield radiation to make γ-rays radiation level outside the annular shields in national standard specified safety scope; Al2O3Ceramics and Kovar alloy composited sensor conduct is connect with measured pipeline by flange. When y-rays traverse substance, ray strength weakens with the increase of material thickness, it has a fixed relationship between ray attenuation quantity and the thickness of the material, this principle is adopted to realize the pulverized coal accumulation thickness measurement of pipeline cross-section.,Experimental results demonstrate that the solution was correct in principle, the instrument system would be able to determine the volume concentration independently while obtain the distribution information of pulverized coal in the conveying pipeline cross section, the method realized absolute measuring that is the measurement result of concentration have nothing to do with flow pattern and solids distribution. Ensure the accuracy of measurement and making high reliability, effectiveness, and real time.