Bamberger Judith A, Greenwood Margaret S
Pacific Northwest National Laboratory, P.O. Box 999, K7-15, Richland, WA 99352, USA.
Ultrasonics. 2004 Apr;42(1-9):563-7. doi: 10.1016/j.ultras.2004.01.032.
Staff at Pacific Northwest National Laboratory have developed a highly sensitive, non-invasive, self-calibrating, on-line sensor to measure the density, speed of sound, and attenuation of ultrasound for a liquid or slurry flowing through a pipeline; the approach can also be applied for measurements made in vessels. The sensor transducers are mounted directly upon the stainless steel wall and the pipeline wall becomes part of the measurement system. Multiple reflections within the stainless steel wall are used to determine the acoustic impedance of the liquid, where the acoustic impedance is defined as the product of the density and the speed of sound. The probe becomes self-calibrating because variations in the pulser voltage do not affect the measurements. This feature leads to the stability of the measurements and the instrument requires much less time and effort to calibrate. Further, the calibration remains constant in time, because it does not depend upon the pulser voltage remaining at a given value. By basing the measurement upon multiple reflections, the sensitivity of the measurement is significantly increased. For slurries with wt% solids concentration of 1% or less, high sensitivity is gained by analyzing attenuation measurements obtained from multiple paths through the slurry. For slurries with higher concentrations of solids, sufficient sensitivity is obtained by analyzing data from a simple transmission. Data are presented that show probe performance for each of these cases: very dilute and highly concentrated kaolin clay slurries.
太平洋西北国家实验室的工作人员开发了一种高度灵敏、非侵入式、自校准的在线传感器，用于测量流经管道的液体或浆料的密度、声速和超声衰减；该方法也可应用于容器中的测量。传感器换能器直接安装在不锈钢壁上，管道壁成为测量系统的一部分。利用不锈钢壁内的多次反射来确定液体的声阻抗，其中声阻抗定义为密度与声速的乘积。由于脉冲发生器电压的变化不影响测量结果，探头实现了自校准。这一特性提高了测量的稳定性，并且仪器校准所需的时间和精力大大减少。此外，校准在时间上保持恒定，因为它不依赖于脉冲发生器电压保持在给定值。通过基于多次反射进行测量，测量的灵敏度显著提高。对于固体重量百分比浓度为1%或更低的浆料，通过分析从穿过浆料的多条路径获得的衰减测量值可获得高灵敏度。对于固体浓度较高的浆料，通过分析简单传输的数据可获得足够的灵敏度。文中给出了这些情况下探头性能的数据：极稀和高浓度的高岭土浆料。
