Study And Design Of The On-Line Measuring System Of Liquid Viscosity

Viscosity of polymer is an important parameter expressing its physical character, and it reflects the flow property of polymer liquid. Viscosity measurement of Polyacrylamide is one of the keys of the oil extraction technology. With the enhancement of measuring requirement in real time, the traditional off-line viscosity measurement is incapable to meet the need of industrial production.In this paper, the rheology characteristic of the Polyacrylamide is analyzed, and the traditional methods of viscosity measurement are studied and summarized. On the basis of the static calibration experiments and dynamic experiments, the configuration of the strain type viscosity sensor is designed independently and the on-line viscosity measuring system is designed. This paper includes following sections:(i) Aiming at the rheology characteristic of Polyacrylamide, many factors are analyzed, such as temperature, pressure, air bubble and so on. The viscosity distributing rule of Polyacrylamide is summarized.(ii) Based on the analysis and study of the principle of target type flowmeter, the measuring model of strain type viscosity sensor is proposed and its mechanical configuration is designed. On the basis of the relationship between the fluid viscosity and the force that the sensor suffered from the flowing liquid, the mathematical model of viscosity measurement is given.(iii) The digital signal process system of viscosity measurement is developed with the singlechip as its microprocessor and the system can realize the on-line signals gathering and data processing.(iv) The digital filtering technology is used to reduce noise jamming, pipeline strong vibration and fluid pulsation. Temperature compensation is adopted to eliminate the effect from environment. Using data buffer of singlechip, both signal sampling and calculation are performed at the same time to realize the signal processing in real time, and it guarantees the viscosity measuring accuracy and real-time performance.(v) The serial communication between singlechip and PC can carried out based on Visual C++, which can realize the measuring data transfer and remote control of this system.The debugging and calibration experiments are conducted to verify the measurement accuracy, stability and reliability of the viscosity measuring system.