Method for Monitoring the Longitudinal Relaxation Time of Flowing Liquids Over the Entire Range of Flow Rate Measurement
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ELECTROMAGNETIC MEASUREMENTS METHOD FOR MONITORING THE LONGITUDINAL RELAXATION TIME OF FLOWING LIQUIDS OVER THE ENTIRE RANGE OF FLOW RATE MEASUREMENTS V. V. Davydov,1,2 N. S. Myazin,1 S. S. Makeev,1 and V. I. Dudkin3
UDC 538.94
The problems of monitoring the state of flowing liquids used in various branches of industry, power production, and agriculture are examined. Means of monitoring the state of flowing liquids based on the phenomenon of nuclear magnetic resonance are discussed. These devices are free of the shortcomings and limitations inherent in the use of optical analyzers and flow-through refractometers. When monitors based on nuclear magnetic resonance are used, the monitored parameters are the relaxation times of the flowing liquid; in particular, the greatest difficulties arise when measuring the longitudinal relaxation time. A method is proposed for monitoring the longitudinal relaxation time of a flowing liquid over the entire range within which its flow rate is measured. A design for a nuclear-magnetic flowmeter-relaxometer is developed for implementation of the new method. The obtained data are compared with measurements of steady-state longitudinal relaxation times of liquid media in a commercial nuclear-magnetic relaxometer; these measurements coincide to within the measurement error. Keywords: nuclear magnetic resonance, magnetic field, longitudinal relaxation time, flowing liquid, signalto-noise ratio.
Introduction. At today’s rate of scientific-technical progress, the number of liquid media and their mixtures employed in various branches of industry, power production, agriculture, and services is constantly expanding [1–6]. In addition, the number of physical, chemical, and biological experiments in which it is necessary to monitor the state of a flowing medium is increasing [5–9]. The greatest complexity arises in monitoring the state of flowing media in turbulent regimes [4, 10–13]. The various devices for monitoring the state of flowing media have a range of shortcomings and limitations. For example, the models developed for optical analyzers are effective for monitoring the state of flowing media with turbidity of no more than 10 FNU. The medium must not contain undissolved particles with sizes greater than the wavelength of the laser light being used. If these conditions are not met, the error in determining the state of the medium increases to 10% (or more in some cases). Flow-through refractometers of various types [14–19] also have a number of limitations when used to monitor the state of flowing media. For example, differential flow-through refractometers [15, 16, 18] are limited by the turbidity of the medium and the presence of undissolved substances. Refractometers based on the phenomenon of total internal reflection are sensitive to sharp temperature drops in the flowing and surrounding media. These drops can occur during experiments, in the course of irregularities in a technical process during industrial production, etc. Study of liquids by the nuclear magnetic resonance metho
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