"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，颗粒由于与管壁的碰撞而带电。在静电带电的基础上，提出了一种测量粉料流量的方法。电学方法利用了高响应度而不阻碍管流的优点，然而，该方法有基本的问题；颗粒与壁面之间的电荷转移既取决于颗粒的初始电荷，也取决于颗粒的静电性质。为了解决这些问题，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。利用矿粉进行的实验发现，该双检测系统对质量流量的测量具有较高的性能。测量的相对误差在10%以内。此外，该测量系统还可以同时测量颗粒电荷。工业上通常使用聚合物粉末和矿物粉末。在气固两相管流中，由于颗粒的碰撞，聚合物粉末在壁面上形成了一层坚硬的涂层。如果管壁是由金属等坚硬材料制成的，这种现象尤其明显。因此，以几种聚合物材料作为检测管道，通过改变粉末流量来评价电流检测的性能。研究发现，含碳的导电聚合物在电流检测中具有较好的稳定性。研究还发现，用导电聚四氟乙烯和导电尼龙两种不同的导电聚合物作为检测管材，可以测量聚合物粉末的质量流量。

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.