"Measurement of powder flow rate in a gas-solids pipe flow based on the electron energy difference"

在气固两相管流中，由于颗粒与管壁碰撞，颗粒带电。提出了一种基于静电起电原理的粉体流量测量方法。电学方法利用高响应性而不阻碍管流，然而，该方法具有基本问题;颗粒和壁之间的电荷转移取决于颗粒的初始电荷和静电性质。为了解决这一问题，我们提出了一种新的电学方法，通过分析由氮化钛和镍等不同材料制成的两个串联检测管产生的电流。通过对矿粉的实验研究，发现该双检测系统在质量流量测量方面具有良好的性能。测量的相对误差在10%以内。在工业上，聚合物粉末和矿物粉末都是常用的粉体材料。在气固两相管流中，聚合物粉末由于颗粒碰撞在管壁表面形成一层刚性涂层。如果管壁由金属等硬质材料制成，这种现象尤其显著。因此，几种高分子材料被检查作为检测管，并通过改变粉末流量来评估电流检测的性能。发现含碳导电聚合物在电流检测上具有优越的上级稳定性。还发现聚合物粉末的质量流率可以通过使用两种不同的导电聚合物来测量，例如，导电聚乙烯和导电尼龙，用于检测管。

In a gas-solids pipe flow, particles are charged as a result of particle collision with the pipe wall. On the basis of the static electrification, a method for measuring the powder-flow rate was proposed. The electrical method takes advantage of high-responsibility without obstructing a pipe-flow, however, the method has fundamental problems ; the charge transfer between a particle and a wall depends both on the initial charge of the particle and on the electrostatic properties. To resolve the problems, we proposed a new electrical method by analyzing the electric currents generated from two detecting pipes in series, which were made of different materials such as titanium nitride and nickel. From the experiments using mineral powders, it was found that the dual-detecting system had high-performance on the measurement of mass-flow rate. The relative error in the measurements was within 10%. Furthermore, the particle charge could be obtained simultaneously in this measuring system.Polymer powders as well as mineral powders are generally used in industry. Polymer powders formed a stiff coationg layr on a wall surface due to particle collision in a gas-solids pipe flow. This phenomenon is especially remarkable if a pipe wall is made of hard material like metal. Therefore, several polymer materials were examined as the detecting pipes, and the performance of the current detection was evaluated by changing the powder flow rate. It was found that electrically conductive polymers containing carbon had superior stability on the current detection. It was also found that the mass-flow rate of polymer powder could be measured by use of two different conductive polymers, e.g., conductive polytetrafluoroetylene and conductive nylon, for the detecting pipes.