RU2493551C2 - Device to identify density of fluid media - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: device to measure density of fluid media comprises a measurement chamber made of non-magnetic material with a float, inside of which there is a magnet-sensitive substance. Also the device comprises a solenoid coil, placed outside the measurement chamber and connected to the output of the controlled voltage source, a sensor coil, connected to the inlet of the source of the controlled voltage and in parallel to the inlet of the measurement indicator. At the same time the measurement chamber has an inlet and an outlet nozzles made as capable of connection to a manifold pipeline with controlled fluid. The body of the measurement chamber float is made from elastic non-magnet material and is filled with magnet-sensitive substance, such as a ferromagnetic suspension.

EFFECT: invention makes it possible to perform continuous density measurement, simplified design, higher accuracy of measurements.

8 cl, 1 dwg

Description

The invention relates to the field of monitoring the density of liquid media and can be used for continuous monitoring of the density of process fluids.

A device for measuring the density of a liquid is known, based on fixing the position of flotation equilibrium created by the electromagnetic force of a solenoid acting on a ferromagnetic core placed vertically in a glass float in its magnetic field, which compensates for the difference in gravity between the float and the buoyant Archimedean force.

The disadvantages of the device are cumbersome, low accuracy, inertia of measurements due to the need to fix the moment of flotation equilibrium through visual observations of the position of the float. [one].

There is another device for measuring the density of a liquid, also containing an electromagnetic solenoid, while the principle of the device is based on measuring the speed of ascent of the float under the action of the resulting Archimedes force and gravity [2].

The disadvantage of this device is the low accuracy of the measurements due to the influence of the viscosity of the liquid and the magnetic field on the speed of movement of the float and the need to monitor its position.

A device is known, adopted as a prototype, comprising a non-magnetic measuring chamber with a controlled fluid and a float inside it, having a non-magnetic material body, containing magnetically sensitive substance inside the body, sensor and solenoid coils located outside the measuring chamber, the sensor coil being connected to the input of an adjustable voltage source and parallel to the input of the measuring indicator, and the solenoid coil is connected to the output of the adjustable source voltage i. [3]

The disadvantages of this device are:

- the impossibility of conducting continuous measurements of the density of the controlled fluid during the process, since the measuring cell must be portion-filled with the test fluid;

- the difficulty of fixing the position of the flotation equilibrium of the measuring chamber float and the low accuracy of fixing this position due to the presence of a solid magnet inside the float, the center of gravity of which does not coincide with the center of gravity of the float body, which creates a moment of rotation of the float relative to the longitudinal axis of the measuring chamber and leads to instability of the position of the float during the measurement process, and this introduces an additional error, which is difficult to take into account with each individual measurement;

- the need to use, in some cases, visual methods for fixing the flotation balance of the float, which does not allow the use of this device in automated systems for measuring and monitoring technological processes;

- the need to use thermostating of the measuring chamber;

- discreteness and inertia of the measurement process;

- low accuracy due to the need for visual control of the position of the float.

The aim of the proposed technical solution is to provide the possibility of continuous density measurement, simplifying the design and improving the accuracy of measurements.

This goal is achieved by the fact that in a device containing a non-magnetic measuring chamber with a controlled fluid and a float inside it, having a non-magnetic material body, containing magnetically sensitive substance inside, a sensor and solenoid coil located outside the measuring chamber, the sensor coil being connected to the input adjustable voltage source and parallel to the input of the measuring indicator, and the solenoid coil is connected to the output of the adjustable source voltage ia, the measuring chamber is additionally equipped with inlet and outlet nozzles for connecting it to the main pipeline with controlled liquid, the body of the measuring chamber float is made of flexible non-magnetic material, a ferromagnetic suspension ("magnetic liquid" is used as a magnetically sensitive substance contained inside the measuring chamber float body )

Compared with the prototype, the proposed technical solution is characterized in that

- the measuring chamber is equipped with inlet and outlet nozzles with the ability to connect to the main pipeline;

- the body of the float is a shell made of elastic non-magnetic material;

- a ferromagnetic suspension is used as a magnetically sensitive substance.

In addition, the housing of the float can be performed:

a) spherical (spherical) shape (to increase the stability of the float);

b) cylindrical shape (to increase the sensitivity of the device);

c) in the form of an ellipsoid of revolution (to reduce the hydraulic resistance of the float and increase the sensitivity);

g) conical shape.

The body of the float can be filled with a ferromagnetic suspension:

a) in its entirety (to increase the sensitivity to the magnetic field);

b) partially (to increase the stability of the position of the float to vibration, etc.) and, therefore, increase the accuracy of measurements, moreover:

c) the volume of the inner cavity of the float, free of a ferromagnetic suspension, can be filled with a magnetically inert medium (for example, silicone oil) to maintain a constant pressure inside the cavity and to prevent evaporation of the magnetic suspension inside it.

The indicated features with their functions were not identified in other technical solutions for density measuring devices, which meets the criterion of "significant differences".

A positive effect in the implementation of the claimed technical solution will be to ensure the continuity of measurements, increase the speed of the device, increase the accuracy of density measurements.

The drawing shows one of the possible options for the device.

The device contains:

measuring chamber 1, which is made of a dielectric non-magnetic material and has an input 2 and output 3 nozzles for connection to the main pipeline. Inside the measuring chamber 1 there is a float 4, which is held in equilibrium by the electromagnetic force of the solenoid 5. The housing 6 of the float 4 is made of an elastic non-magnetic material and is filled with a magnetically sensitive substance 7, and a ferromagnetic suspension is used as a magnetically sensitive substance. The magnitude of the movement of the float is determined by the current value of the sensor coil 8 connected to the input of an adjustable voltage source 9, and in parallel to the input of the measuring indicator 10.

In this case, the float body can be made:

a) spherical (spherical) shape (to increase the stability of the float);

b) cylindrical shape (to increase the sensitivity of the device);

c) in the form of an ellipsoid of revolution (to reduce the hydraulic resistance of the float and increase the sensitivity);

g) conical shape.

The body of the float can be filled with a ferromagnetic suspension:

a) in its entirety (to increase the sensitivity to the magnetic field);

b) partially (to increase the stability of the position of the float to vibration, etc.) and, therefore, increase the accuracy of measurements, moreover:

c) the volume of the inner cavity of the float 11, free of ferromagnetic suspension, is filled with an inert medium to ensure constant pressure inside the cavity and to prevent evaporation of the ferromagnetic suspension (for example, silicone oil).

The device operates as follows:

the controlled fluid circulates in the measuring chamber 1 through the inlet 2 and outlet 3 nozzles connected to the main pipeline. When the density of the controlled fluid changes, the float 4 is shifted relative to the initial position. The magnitude of the movement of the float is determined by the current value of the sensor coil 8, recorded by the measuring indicator 10 and depending on the density of the controlled fluid:

I = kΔh,

where I is the current value of the sensor coil, A; k is the coefficient of proportionality; Δh - displacement of the float, depending on the density of the controlled fluid (and determined by the ratio:

, $$\Delta h=\frac{\mathrm{four}}{3}{\rho }_{m\mathrm{well}}\cdot R\cdot \left(\mathrm{one}-\frac{\rho }{\rho +\Delta \rho }\right)$$

,

where R is the characteristic radius (size) of the float, m; ρ _mzh - the density of the magnetic fluid, kg / m ³ ; ρ is the density of the controlled fluid, kg / m ³ ; Δρ is the change in the density of the controlled fluid, kg / m ³ .

The signal from the sensor coil 8 is fed to the input of the regulated voltage source 9 and the measuring indicator 10, the output signal from the regulated voltage source 9 is supplied to the solenoid 5, the electromagnetic force of which the float 4 is held at level h in the cell, depending on the current density value p of the controlled fluid.

The proposed technical solution can find application for continuous measurement, for example, of the density of liquid petroleum products flowing through the main pipeline, as well as in closed systems for regulating the density of process liquids.

Sources used

1. Clarke A.L. Density determination on small liquid samples, - J. Scient. Instrum., 1967, vol. 44, No. 5, p. 382-384.

2. Emmet R.T., Millero F.J. Direct measurement of the specific volume of seawater from -2 to 40 ° C. - J. Geophys. Res., 1974, vol. 79, No. 24, p. 3463-3472.

3. Beams J.W., Clarke A.M. Magnetic suspension balance method for determining densities and partial specific volumes. - Rev. Sci. Instrum., 1962, vol. 33, No. 7, p. 750-753.

Claims (8)

1. A device for measuring the density of liquid media containing a measuring chamber made of non-magnetic material with a float inside which is a magnetically sensitive substance, a solenoid coil located outside the measuring chamber and connected to the output of the adjustable voltage source, a sensor coil connected to the input of the adjustable voltage source and parallel to the input of the measuring indicator, characterized in that, in order to improve accuracy and ensure continuity of measurements, measure te a chamber having inlet and outlet adapted to connect to the main conduit at a controlled liquid float housing of the measuring chamber is made of elastic material and filled with a magnetically-responsive substance, for which a ferromagnetic suspension may be used. 2. A device for measuring the density of liquid media according to claim 1, characterized in that the body of the float is made in the form of a sphere. 3. A device for measuring the density of liquid media according to claim 1, characterized in that the body of the float is made in the form of a cylinder. 4. A device for measuring the density of liquid media according to claim 1, characterized in that the body of the float is made in the form of an ellipsoid of revolution. 5. A device for measuring the density of liquid media according to claim 1, characterized in that the body of the float has a conical shape. 6. A device for measuring the density of liquid media according to any one of claims 1 to 4 and 5, characterized in that the body of the float is completely filled with a ferromagnetic suspension. 7. A device for measuring the density of liquid media according to any one of claims 1 to 4 and 5, characterized in that the body of the float is partially filled with a ferromagnetic suspension. 8. A device for measuring the density of liquid media according to any one of claims 1 to 4 and 5, characterized in that the volume of the inner cavity of the float, free of a ferromagnetic suspension, is filled with an inert medium, for example silicone oil.