振动管式流体密度传感器研究

On Vibration Tube-type Liquid Density Sensor

介绍一种应用于井下自由衰减振动式流体密度传感器。传感器基于管内流体密度与管自由衰减振动周期的非线性关系理论 ,采用独特的电磁激振和动圈检振的激、检振方式 ,以PIC16F87X微处理器为核心 ,配合少量模拟电路完成流体密度的测量 ,并提供曼彻斯特编码输出 /输入和模拟输出方式与外界进行接口。实验结果表明 ,流体密度与振动管的自由衰减振动周期成近似线性的函数关系 ,其非线性程度是由传感器的形状和材料参数决定的 ;随着振动管内流体密度的增加 ,其振动管自由衰减的振动周期也增加。这种机电一体化的流体密度传感器在井下应用时必须进行井场刻度以及温度和压力的校正。

Density is an important parameter for identifying liquid in borehole. A new downhole free attenuation vibration liquid density sensor is introduced.Based on the nonlinear relationship of the liquid density inside the tube and the free attenuation vibration period of vibration tube ,a special mode using the electromagnetic hammer to drive or excite and the active loop to receive signals is developed.In this design ,the liquid density is got by a few analog circuits around PIC16F87X micro-controllers ,and the sensor is interfaced with outside by Manchester code output/input mode and analog output mode. Experiments reveal that the liquid density and the free attenuation vibration period are approximate linear functional relation which depends on the sensor shapes and materials parameters. The vibration period increases with the increase of liquid density in the vibration tube. Wellsite calibration, temperature and pressure correction must be made while the sensor is used in the borehole.