リング状ヒータを用いた管外式気体用流量計の高精度化

抄録

Measurement of steam flow rate is indispensable for a performance diagnosis and an energy solution in factories. However, a sensor installation for steam flow is generally difficult. Because the factories needs to be out of operation temporarily, in the case of installation of conventional flowmeter such as orifice type and vortex type. And steam pipes are necessary to be cut for the installation. Accordingly, clamp-on type steam flowmeter is hoped to be developed.
Therefore, we devised “heater method” for steam flow measurement. A circumferential heater is attached to the outside of a tube. Then, axial temperature distribution on the tube outside is measured. Steam velocity is analyzed on the basis of the temperature distribution, considering heat transmission in the pipe and thermal conductivity in steel pipe. The sensor is heat-resistant and possible to measure high temperature fluid, because it is comprised of the heater, thermocouples and insulator. This paper reports air and steam flow rate measurements by the heater method, and analysis of physical phenomenon such as temperature boundary layer and thermal conductivity in the pipe in case of thin area heating. Then, velocity analysis program was developped on the basis of the results, and each analyzed fluid velocity was compared with reference fluid velocity.