RU38941U1 - DENSITY OF LIQUID - Google Patents

Abstract

LIQUID DENSITY METER (ПЖ) refers to measuring equipment and can be used in monitoring and control systems for technological processes. The pancreas determines the density by measuring the time t ₁ and t ₂ , the passage of a fixed distance Δh in the FS with a full immersion float (BCP) vertically, up and down, respectively, where is a measure of the density of FS. The pancreas consists of a housing 1 with a measuring cavity 2 and the IFR 3 in it. The float is equipped with a permanent magnet 4, which is placed in the part of the body of the pancreas by means of a hinge with a horizontal axis 10, and the SPP and the magnet are connected by a lever 9, which has the ability to swing on the axis 10 in a vertical plane. The housing is equipped with two sensors for monitoring the position of the SPT and an electromagnet with an open magnetic circuit, in the gap of which is located part of the housing with the magnet of the float. The pancreas has a stabilized electromagnet power source and a controller with control, measuring and computing functions. The novelty of the pancreas lies in the design of the site of force impact on the IFR and the placement of the latter in the body of the pancreas. The object of the patent provides higher consumer and metrological properties of products during its implementation than previously known.

Description

The utility model relates to density measuring devices and can be used to measure the density of liquid media, for example, oil and oil products.

Known devices for measuring the density of liquid media, in one form or another [1-4], for example, electromagnetic densitometers contain a measuring vessel with a measured liquid medium, a so-called complete immersion float placed inside the vessel with a permanent magnet installed in it, located in it magnetic field of the solenoid and one float position sensor. The density is judged by the current of the winding of the solenoid included in one way or another in the measurement circuit. A common drawback of densitometers [1-4] is the “zero mark” problem that has not been completely resolved, namely the presence of a measurement error due to the displacement of the float relative to the zero reference point. In addition, the devices, judging by the descriptions, are not devoid of circuit and design difficulties. In addition, in densitometers [1-4], changes in the viscosity of the medium being measured create an additional error in the measurement of density. The density measurement of highly viscous liquid media is provided, for example, by a known densitometer [5] for measuring the density of those with high viscosity, where the test fluid is placed in a special cavity inside the float with a magnet, and the vessel is filled with a control fluid with a known density and then the density measurements are performed using the same magnetically -float method.

The disadvantage of this device is its purely laboratory design and the difficulty of adapting it for process control systems without significant design refinement.

The closest technical solution (prototype) to the claimed device is a density meter device [6], having

Increased speed and sensitivity while simplifying the measurement circuit. A known densitometer consists of a measuring capacitance with a measured liquid, an inductor, a ferromagnetic core with a hollow float drawn to it in the presence of current in the inductor. When the current is turned off, the float, under the action of the buoyancy force, pops up and comes into contact with the sensitive element of the sensor that controls the start-stop of the timer. The method of measuring density in this case consists in measuring the time of movement (floating) of the float, which is a measure of the desired density of the liquid. Indeed, time can be measured with arbitrarily high accuracy, (and, therefore, density). And although with small displacements of the float [6] the effect of viscosity changes on the accuracy of density measurement is insignificant, nevertheless, as practice shows, it is present. Thus, the known device also has a significant drawback, namely, the effect of viscosity on the result of measuring the density of a liquid, as well as a change in viscosity as a function of temperature.

The required technical result (otherwise, the purpose of creating the claimed object) is to provide a well-known technical solution to higher consumer properties by minimizing or eliminating the influence of the viscosity of the measured liquid medium and temperature, and, therefore, improving the accuracy of measuring the desired density.

As shown by bench and industrial tests of the inventive device and the operating experience of the prototype device, the required technical result is achieved by the fact that the known liquid density meter containing a housing with a measuring cavity, a float (in the cavity) with a permanent magnet, an electric sensor for the upper position of the float connected to the timer and a density calculation unit, an electromagnet, an electromagnet power supply, contains an electric sensor for lowering the position of the float, also connected to a timer and a block you numbers

the density, the float and the permanent magnet are interconnected by a lever with the possibility of its swinging in a vertical plane, the horizontal axis of swing of the lever is located in the center of the permanent magnet, the electromagnet is made with an open magnetic circuit and winding, part of the body with a permanent magnet of the float is placed in the gap of an open magnetic circuit of the electromagnet, when the permanent magnet of the float is symmetrical both with respect to the swing axis and relative to the lever, the power supply of the electromagnet is made in the form of stabilizers continuous source of direct current, and calculation unit density is designed as a controller with a power polarity switching functions electromagnet measuring time intervals float movement upwards t ₁ and down t ₂ or vice versa (or, equivalently, moving speed of the float up υ ₁ and down υ ₂ , or vice versa), control the quality of stabilization of power supply and calculate the density of the liquid medium.

The required technical result is ensured by the presence of the essential features (characterizing the proposed densitometer device for measuring the density of the liquid medium) of the above distinctive features, and the non-detection in the public sources of patent and technical information of equivalent technical solutions with the same properties with undoubted industrial applicability implies that the claimed object meets the criteria utility model.

The drawing shows a schematic diagram of a liquid density meter. The densitometer consists of a housing 1 with a measuring cavity 2, a float 3 (in the cavity 2) with a permanent magnet 4, an electric sensor 5 of the upper position of the float connected to a timer and a density calculation unit, electromagnet 6, and an electromagnet power supply 7. The device also contains an electric sensor 8 of the lower position of the float, connected, like a sensor 5 with a timer and a density calculation unit. The float and the permanent magnet are connected

between each other by a lever 9 with the possibility of swinging in a vertical plane, the horizontal axis 10 of the swing of the lever is located in the center of the permanent magnet, the electromagnet is made with an open magnetic circuit 11 and winding 12, part 13 of the housing with a permanent magnet of the float is placed in the gap of the electromagnet magnetic circuit, while the permanent magnet the float is symmetrical both with respect to the swing axis and with respect to the lever, the power supply of the electromagnet is made in the form of a stabilized DC source, and the timer and the calculator Density variations are made in the form of a single controller 14 with functions: measuring the time intervals of the float moving up t ₁ and down t ₂ , or vice versa (or the speed of the float moving up υ ₁ and down υ ₂ , or vice versa) when switching the polarity of the electromagnet his own teams, and, accordingly, calculating the desired liquid density, taking into account the density scale factor of the density meter of a particular design, that is, the claimed device.

A prerequisite for the normal functioning of the device (densitometer), guaranteeing its accuracy characteristics, is the mode of low speeds of movement of the float, when the liquid flows around the latter laminarly, and the movement of the float obeys the Stokes law [7].

The liquid density meter works as follows. In the initial state, after filling the measuring cavity 2 with liquid (the lines for supplying and discharging the liquid medium are conventionally shown by arrows in the drawing), the float 3 is in an indefinite position, or, for example, between sensors 5 and 8 located (along the height of the housing) from each other on the distance Δh, or in one of the extreme positions, conventionally shown in the drawing by dashed lines. When you turn on the source 7 constant (stabilized) current with a certain polarity, defined (and changed with a certain

periodicity to the opposite) by the controller 14, the float 3, under the action of the electromagnet 6 interacting with the permanent magnet 4, will begin immersion (floating up), crossing the sensitivity zone of one of the sensors (5 or 8) of the upper or lower position of the float. The first actuation of any of the sensors (or 5, or 8) to the float is not yet informational from the position of density measurement, but it uniquely determines the location of the float. After that, at the command of controller 14, the polarity of the direct current source 7 changes, and, consequently, the direction of the magnetic field of the electromagnet, under the influence of which the direction of movement of the float changes, that is, the direction of rotation around the horizontal axis 10 of the permanent magnet 4 with lever 9 and float 3. Under the action of the efforts of the electromagnet 7, the float 3 will begin immersion (floating), again passing through the sensitivity zone of the same sensor 5 (8), thereby including a timer located in the controller 14 at the expense of time t ₁ . When the float reaches the sensitivity zone of the sensor 8 (5), the time t ₁ counts off. With the next change in the polarity of the direct current source, the float 3 will begin to reverse, again crossing the sensitivity zone of the position sensor 8 (5) and including the controller timer at the expense of time t ₂ . When the float 3 reaches the position sensor 5 (8), the time t ₂ counts off. Given the stability of the power supply current of the electromagnet 6, the time the float moves up (or down) depends on the force of the electromagnet; in this case, always t ₁ ≠ t ₂ and υ ₁ ≠ υ ₂ .

In order to provide control (measurement) of fluid density, the measuring cavity is connected to the pipeline through a bypass line using valves (not shown), which can be controlled in automatic measurement mode using

the controller, and the body of the densitometer and the tubular elements of its connection provide a heat-shielding shell.

Consider the algorithm for obtaining the desired density, which allows us to evaluate the possible effect of fluid viscosity on the process and the measurement result.

We write down the conditions for the balance of forces acting on the float when it moves uniformly up or down.

With a uniform movement of the float up and down, we have, respectively:

where: P = ρ _p V _p g - weight of the float;

F _E - traction force of an electromagnet (solenoid);

F _A = ρ _W V _p g - Archimedean force acting on the float;

F ' _T = 3πμDυ ₁ and F'' _T = 3πμDυ ₂ - friction forces of the float in the liquid under the condition that the liquid flows around the float laminarly, up (or down), respectively;

g is the acceleration of gravity;

ρ _W and ρ _p - the density of the measured liquid and the float, respectively;

μ is the dynamic viscosity of the liquid;

D is the diameter of the float;

υ ₁ and υ ₂ - the speed of movement of the float relative to the liquid, up and down, respectively.

We transform equations (1) and (2) to the form:

From equations (3) and (4) we have, respectively:

The speed difference υ ₁ and υ ₂ and their sum will be respectively equal to:

Dividing the difference (7) by the sum (8), we obtain:

where F _e -Const;

V _p - the volume of the float. Finally we have:

or (which is the same):

where K is the density scaling factor.

From formulas (11) and (12) it follows that the density of the measured medium ρ _W does not depend on the viscosity μ of the liquid.

The set of essential features of the densitometer (including distinctive ones) ensures the achievement of the required technical result, meets the criteria of the “utility model” and is subject to protection by the RF title document (patent) in accordance with the applicant’s request.

SOURCES OF INFORMATION USED WHEN DRAWING UP A DESCRIPTION OF A USEFUL MODEL:

1. USSR, A.S. No. 1642319, cl. G 01 N 9/12, 9/22, 1991.

2. USSR, A.S. No. 630557, M. Cl. ² . G 01 N 9/12, 1979.

3. USSR, A.S. No. 389439, M. Cl. G 01 N 9/12, 1973.

4. RF patent No. 2082151, M. Cl ⁶ . G 01 N 9/12, 1995.

5. Kivilis S.S. Density meters - M., Energy, 1980, p. 108

6. Evstigneev A.N. et al. Remote digital liquid density meter. - In the book: Intensification of processes and equipment of food production. L.T.I. 1976, p. 50 ... 53., Prototype

7.X. Kuhling. Handbook of Physics. M .: "World", 1982, p.129

Claims (1)

A liquid densitometer comprising a housing with a measuring cavity, a float (in the cavity) with a permanent magnet, an electric float upper position sensor connected to a timer and a density calculation unit, an electromagnet, an electromagnet power supply, characterized in that it contains an electric float lower position sensor, connected to the timer and the density calculation unit, the float and the permanent magnet are interconnected by a lever with the possibility of its swing in the vertical plane, the horizontal axis of the rock aha is located in the center of the permanent magnet, the electromagnet is made with an open magnetic circuit and winding, a part of the body with a permanent magnet of the float is placed in the gap of the open magnetic circuit of the electromagnet, while the permanent magnet of the float is symmetrical both with respect to the swing axis and relative to the lever, the electromagnet power source is made in the form a stabilized DC source, and the density calculation unit is made in the form of a controller with functions for switching the polarity of the power supply of the electromagnet, and measurements were timeslots float movement up and down t ₁ t ₂ or vice versa (or, equivalently, the speed of movement of the float up and down υ ₁ υ _2, or vice versa), quality control and power stabilization calculating fluid density.