SU1673847A1 - Method for measuring flow rate of a liquid by its nuclear magnetic resonance - Google Patents

Abstract

The invention relates to a measurement technique, in particular to the measurement of velocity and flow rate of a fluid. The aim of the invention is to simplify the measurement and expansion of informative possibilities. The measured fluid through conduit 1 enters the magnetic field created by magnets 2 with a gradient along the axis of conduit 1. The magnitude of the gradient is set using the gradient defining unit 4. The NMR signal detected by the coil 5 enters the spin detector 6, then is fed to the input of the synchronous detector 11, and a change in flow causes an asymmetry of its output signal. The flow measure can be the difference or the ratio of the areas of the upper and lower parts of the NMR signal curve. The magnitude and sign of asymmetry are analyzed and displayed in block 12 of registration. 2 Il.

Description

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(21) 3699386/10 (22) 02.12.83 (46) 30.0891. Bul №32

(71) Belarusian State University. V.I. Lenin

(72) A.E.Pr Khin, S.S.Shushkevich and I.O.Oobey

(53) 681.121.8 (088.8)

(56) Calculation and design of flow meters / Ed. P.P.Kremlevskogo. L .: Mechanical Engineering, 1975, pp.150-152.

USSR author's certificate N 208985, cl. G 01 F 7/12, 1966.

(54) METHOD FOR MEASURING THE SPEED (FLOW) OF THE LIQUID BY NMR METHOD

(57) The invention relates to a measurement technique, in particular to the measurement of velocity and flow rate. The aim of the invention is to simplify measurement and expand informative capabilities. The measured liquid through conduit 1 enters a magnetic field created by magnets 2 with a gradient along the axis of conduit 1. The gradient is set using the gradient defining unit 4. The NMR signal detected by the coil 5 enters the spin detector 6, then is fed to the input of the synchronous detector 11, and a change in the flow rate causes an asymmetry of its output signal. The flow measure can be the difference or the ratio of the areas of the upper and lower parts of the NMR signal curve. The magnitude and sign of asymmetry are analyzed and displayed in block 12 of registration. 2 Il.

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The invention relates to a measurement technique, in particular to the measurement of velocity and flow rate of a fluid.

Purpose: • Enhance measurement and expand informative capabilities.

The method is as follows. Pre-polarized liquids are passed through a pipeline placed in a constant magnetic field having a gradient along the axis of the pipeline. The change in the NMR signal determines the direction of the flow and its velocity.

The essence of the method is explained by the operation of the device in which the proposed method is realized and the waveforms of the NMR signals.

Figure 1 is a schematic diagram of the device; figure 2 - waveform signals of NMR with different modes of operation.

The device comprises pipeline 1, magnets 2, current shims 3 gradient magnetic fields, a gradient setting unit 4, an NMR signal registration coil 5, a spin detector 6, modulation coils 7, a modulation generator 8, sweep coils 9, and a sweep device 10, synchronous detector 11 and registration unit 12.

The flow meter based on the proposed method works as follows.

The measured fluid through pipeline 1 enters the magnetic field created by magnets 2 and current shims 3 with a gradient along the axis of pipeline 1. The magnitude of the gradient is set using the gradient defining unit 4 4. The NMR signal. registered by the coil 5, enters the spin detector 6. then is fed to the input of the synchronous detector 11, the output of which is connected to the input of the registration unit 12.

In Figure 2, it can be seen that a change in the flow rate causes an asymmetry of the output signal of the synchronous detector 11, which is uniquely associated with the magnitude and direction of fluid flow. Here 2a is the signal from the stationary liquid; 26 - signal from the fluid flow at a speed of 1.2 cm / s; 2c - signal from the fluid flow at a speed of 5 cm / s; 2d is the signal from the oppositely directed fluid flow at a speed of 5 cm / s.

A measure of the velocity (flow rate) of a fluid can be the difference or the ratio of the areas of the upper and lower parts of the NMR signal curve. The magnitude and sign of asymmetry is analyzed and displayed in block 12.

Claims (1)

Invention Formula A method of measuring the velocity (flow rate) of a liquid by NMR, which consists in pre-polarizing a moving fluid, exposing it to constant and alternating magnetic fields and recording an NMR signal, characterized in that, in order to simplify the measurement and expansion of informative possibilities, a permanent magnetic the field is created with a constant gradient along the axial line of the pipeline, and the velocity (flow rate) and the direction of the fluid are judged by the change in the NMR waveform.