Measurement Of The Mean Temperature Across The Section Of Air Powdered-coal Mixture Pipe In Primary-air Conveying Powder System Of Boiler

Recently with the fluidization technique studied deeply, the mechanism of gas-solid flow and the hydro-mechanical behavior and conveying quality of it attracts more and more researcher. It is necessary to make a large of experimental research in order to learn the mechanism of gas-solid flow and the hydro-mechanical behavior and conveying quality of it. At the same time, experimental data are foundation of the establishing of many gas-solid model. The result of experiments depends on the performance of experimental instruments and the rationality of testing method. Therefore, convenient and reliable testing technique of gas-solid flow is a necessary tool in the research of gas-solid flow.At present, direct testing method (the method directly contacting with the object researched) is mostly applied in gas-solid testing. Though it is relatively exact, this method is not so perfect: firstly, applying this method the sampling head tends to disturb the gas-solid flow; secondly, the sampling head may be ablated badly; fourthly, with this method, the value gained is a local one, not a mean one. In this paper, to the primary air conveying powder system in power plant powdered-coal boiler, a method is raised to measure the section mean temperature through surface-type temperature measuring of the air-powdered-coal mixture pipe. Namely, with the foundation of numerical simulation of equal-phase flow model, a arithmetic and software is worked out to realize the measurement of this mean temperature, the measured result of push-in type measurement is used to test that of the surface-type measurement.In the numerical simulation, taking the mixing segment of the primary-air conveying powder system as studying object, the equal-phase flow model is used to simulating the flow of primary-air and air-powdered-coal mixture, then the relation is founded of mean temperature in the pipe and that of the outer-layer of the pipe, and the result of computation is i'it into a formula. With this foundation, the arithmetic and software can be worked out to measure the mean temperature of air-powdered-coal mixture. In the local experiment, aiming at several working condition, the measured result of push-in type measurement is used to test the veracity of the surface-type measurement. As a result, bothagree with each other smoothly. So, this software can be used in actual air-distribution testing system to measure various parameters of primary-air conveying powder system.