Research On The Measurement Of Gas-solid Flows' Concentration Based On Resistance Character

The application of the gas-solid flow technology is more and more abroad, and the concentration measurements of gas-solid two phase flows have become more and more important. For example, in the operation of power plant boilers, the concentration measurement of the primary air with pulverized coal on-line, plays a very important role in the boiler operation. Therefore, it is necessary to find an accurate, direct, reliable measurement method on-line for the concentration of two-phase flow.Target flowmeter is a kind of abroad used apparatus, and it has own unique characteristic. There are researchers who apply target flowmeter to measure the concentration of gas-particle two phase flows, and its applicability is already proved. So it is necessary to research the following problems: which target is more sensitive to the concentration and the reason for it, which kind of velocity field is around the targets, and which law is between the force on the targets with the velocity and concentration.This paper pilot studied the questions above with the numerical simulation and experimental methods.We used a discrete phase jet, viscous turbulence model and SIMPLE algorithm with the numerical simulation software FLUENT in numerical simulation,. Through seven groups of simulations on the relation about the geometry dimension and windward angle with the force on targets, we found the most sensitive geometry dimensions and windward angles to the concentration of two-phase every series, found the typical targets of four most sensitive targets series to the two flow concentration, and also found the sphere coronet target with sphere-protruding inner surfaces was the most sensitive target to the concentration of two-phase. To the sphere coronet target with sphere-protruding inner surfaces, we did the calculations about the relation of the force on it with the flow velocity, and the comparison with the air flow. At last, differential equation is set up on the relationship between the three independent variables (velocity, the powders-quantity, the force on targets). And based on the differential equation, software SPSS is used to fit the results of the two-phase flow and the relationship between the three independent variables is gained and the error is quit little.We set up a two-phase flow test rig in the experimental study, did the experiments of pure air flow varying speed and varying concentration with constant speed, got the results and error analysis. For the studied four targets under the state of two phase flow, one side, the forces on the targets are all less than that in the simulation .The main reason is that the wind velocity is different in the experiment and the simulation. The other side, it is found that the rank of the force on targets in the experiment is completely consistent with that of the simulation. Among of the four targets, the force on the convexity inner surface-crest is the biggest. At last, the experimental error is analyzed and the results are fitted, the relationship between the three independent variables (the velocity of the two-phase flow, the powders-quantity, the force on targets) is gained and the error is quit little.