RU152642U1 - DEVICE FOR CONTINUOUS MEASUREMENT OF VISCOSITY AND LIQUID DENSITY IN PIPELINES - Google Patents

Abstract

1. Udnivipzhvtsivvtlit vksuik from chkss nvpkntprikszk ornvss addnvpn vsrt zhsspok attiprvvdpmU poipn2. UPP 1, from chzchkizosf3. Upp 1, ht critical pixel = 10d inl = 5d peak

Description

The device is intended for continuous measurement of the viscosity and density of liquids in the pipelines of technological lines, in particular in the process of monitoring the production of drying oil, pentaphthalic and glyphthalic varnishes.

Viscosity is the most important physical and chemical characteristic of many liquid and gaseous media. Viscosity is a qualitative characteristic of intermediates and finished products of various industries, since it directly depends on the structure of the substance and shows the physicochemical state of the material and the changes that occur in the technology.

To determine the viscosity, a measuring device, a viscometer, is used.

In the paint and varnish industry, a viscometer is most often used, which is a conical container, with a top down, a volume of 100 ml, in the lower part there is a calibrated hole in the container through which fluid flows. Viscosity is determined by the time of fluid flow under the action of gravity, in seconds. Since the viscosity of the material depends on temperature, then with increasing its viscosity decreases. In this regard, it is necessary to withstand all samples at a certain temperature to average the measurements over the entire volume.

The disadvantage of this method is that it takes a long time to withstand the sample in order to achieve a given measurement temperature (cooling or heating). In addition, the measurement itself also requires a long investment of time, especially at high viscosity of the material.

It is known to measure the viscosity of a liquid by the “falling balls” method, according to which the viscosity of a liquid medium is judged by the uniform speed of immersion of a ball probe of a known radius and a known material density in it. One of the drawbacks of this method is that to measure the viscosity of the liquid by the method of "falling balls" with acceptable accuracy, it is necessary to ensure the conditions of laminar flow around the moving ball with the investigated liquid.

In the method according to the patent of the Russian Federation No. 2082153 IPC G01N11 / 12 they use a ball probe of radius R and density p ₃ immersed in a liquid, a computing unit, a probe acceleration unit, a vertical component of the probe velocity and a probe acceleration unit, a vertical component of the probe velocity and a knot for returning the probe to its initial position, the input and output of the computing unit being connected to the output of the vertical component of the speed of the probe and the input of the probe acceleration unit, respectively, and the ball probe interacts cally from the acceleration unit at the start of measurement with the probe unit and return to the original position at the end of the motion in the measurement respectively.

The disadvantage of this method is the complex hardware design, requiring accurate measurement of speed and time, which determines the accuracy of the final result, as well as the need for relatively complex and time-consuming calculations.

A device is known according to the German patent (DE 19529722; IPC B63H 21/38; G01N 11/12) containing a measuring cylinder with end holes. Inside the measuring cylinder is a sensitive element made in the form of a ball. At the bottom of the measuring cylinder is a temperature sensor, and position sensors are installed along its height. The position and temperature sensors are connected to the outputs of the software and computing unit, the output of which is connected to the display unit. The end openings of the measuring cylinder are connected by a bypass measuring pipe in which the electrohydro valve is installed.

The disadvantage of this technical solution is the dependence of the measurement results on the ratio of the specific gravities of the ball and the medium to be measured, the need for different liquids in terms of the specific gravity to select different balls, take into account the change in the specific gravity of the liquid on the temperature and operating time.

Rotational methods for measuring viscosity have more capabilities. They can be used for both periodic and continuous measurements.

The essence of the method is to place the liquid in a closed hollow cylinder and bring it into rotation, and rotate it over time, until the angular velocity of the investigated liquid in the cylinder becomes constant, instantly stop the rotation of the cylinder, measure the transition time t _nn between the first state, in where the surface of the liquid has the form of a paraboloid of revolution, and its parameters are determined by the angular velocity of the fluid ω ₁ , and the second state in which the parameters of the paraboloid of rotation are determined by the angular soon ью ω _nop , the time t _{nn of} the liquid taking the second state (ω = ω _nop ) is a measure of viscosity and is determined by calculation using hydrodynamic formulas (see L. Loitsyansky, Mechanics of liquids and gases. - M; Science; 1970; )

The disadvantages is that when implementing the method requires a significant investment of time on thermostating the temperature of the liquid, bringing the temperature to a certain value, for reproducibility of the results. The method is applicable to low- and medium-viscous liquids, and also requires the use of sophisticated equipment for recording time using a sensor based on a cylindrical volume resonator and a microwave tunable in frequency. This design of the measuring device is intended for periodic measurement of fluid viscosity.

The closest technical solution (prototype) to the claimed is RF patent No. 139168 IPC G01N 9/12, G01N 11/12 for a utility model, in accordance with which the working fluid flows through the device, exerts pressure on the long shoulder of the two shoulders of the lever, which short arm through the tight the membrane and the pusher acts on the capacitor of variable capacity, changing its capacity, and this change is reflected on the screen of the indicating device.

The disadvantage of this utility model is that the transmission of force is carried out through a membrane, the material of which has high requirements - chemical resistance, elasticity, resistance to elevated temperatures, etc., deviation from which can lead to measurement errors.

The objective of the proposed utility model is to eliminate the disadvantages of the known technical solutions, providing the possibility of continuous measurement of the viscosity of the liquid in the course of the process.

This can be achieved by using strain gauges, using the property of electrically conductive materials (metals, semiconductors) to change the electrical resistivity during their deformation. As conductive materials, metal films are typically sprayed onto a flexible dielectric substrate. Recently, semiconductor sensors have been used, having the following advantages:

- a very high deformation sensitivity, allowing measurements to be made without amplifiers, with conventional ohmmeters;

- a very high threshold sensitivity, allowing to measure the deformation of metals from a millionth of a millimeter on a linear meter;

- high sensitivity allows you to measure a very small force in the nominal range;

- the small sizes of the strips of the semiconductor (length 1-10 mm, width 0.2-0.4 mm, thickness 0.01-0.03 mm) allow the production of small and light sensors;

- silicon semiconductors from -70 ° C to 300 ° C are deformed without measurable hysteresis;

- Strain gages made of silicon and gold have excellent resistance to corrosion.

The essence of a semiconductor strain gauge is a significant change in its electrical resistivity with mechanical deformation. Under the influence of a mechanical load, a change in the electrical conductivity occurs in a certain crystallographic axis of the semiconductor single crystal. The active part (a strip of semiconductor) is glued with a special tensometric glue to a surface that can be deformed. Lead wires metal. Temperature accuracy is also affected by temperature changes. Therefore, to compensate for spurious effects on the measurements, the connection circuit to the Wheatstone bridge is used, which is four resistors connected to an electric bridge powered by a constant voltage source. One of the resistors is variable and is designed to balance the bridge, so that in the absence of applied force, the signal is made equal to zero. The second strain gauge is used to measure the strain when a force is applied (this changes its electrical resistivity), for which it is glued to the substrate in the longitudinal direction, along the line of action of the force, the third and fourth strain gauges are glued in the transverse direction, insensitive to deformation. With a change in temperature, if the temperature of all three resistors is equal, the sign and magnitude of the change in electrical resistance (caused by a change in temperature) are equal, and the temperature departure is compensated. This is primarily due to the high temperature coefficient of resistance of the strain gages.

The technical result is achieved, and the problem is solved by using semiconductor strain gauges in a device for continuous measurement of viscosity and liquid density.

A device for continuously measuring the viscosity and density of a liquid is illustrated in graphic materials.

In FIG. 1 is a schematic illustration of a device for measuring viscosity and density of a liquid.

In FIG. 2 is a diagram of a measuring bridge of a device for measuring viscosity and density of a liquid.

The device of FIG. 1 consists of a measuring tube 1 of a certain diameter d, inside of which a measuring capsule is coaxially mounted.

The device operates as follows: a moving fluid flow (indicated by an arrow, Fig. 1) exerts pressure on the front cowl fairing 2, which is rigidly connected to the pusher 3, which transfers the pressure force to the bottom of the cup 4, causing elastic deformation of the thin walls of the cup. On the outer surface of the walls of the glass made of an elastic dielectric material (for example, polyamide), three silicon semiconductor strain gauges with gold ends are glued with a special strain glue, with the strain gauge R _x glued along the wall of the glass, and two strain gauges R ₂ and R ₃ glued transversely direction. The strain gauge R _x receives the longitudinal force together with the elastic deformation of the glass wall, and the resistors R ₂ and R ₃ are insensitive to deformations, since they are glued in the transverse direction to the action of the applied force. Such a scheme allows measurements to be taken over a wide range of temperatures, because when the temperature changes, if the temperature of all three resistors is equal, the sign and magnitude of the change in resistivity caused by the temperature change are equal, and the temperature departure is compensated.

Strain gages are included in the two arms of the Wheatstone balanced bridge, powered by a 12-24V DC voltage source (AD bridge diagonal) (Fig. 2). Using a variable resistor R ₁ , the bridge is balanced so that, in the absence of applied force, the diagonal voltage is equal to zero. A signal is taken from the diagonal of the BC bridge, then fed to the measuring device or to the differential amplifier.

When the ratio R ₂ / R ₁ = R _x / R ₃ is fulfilled, the voltage of the diagonal of the bridge is zero. During deformation, the resistance of the strain gauge R _x changes (for example, increases with tension), this causes a decrease in the potential of the connection point of the resistors R _x and R ₃ (point B) and a change in the voltage of the diagonal BC of the bridge (useful signal).

The measuring tube is built into the production line in a vertical position so that the fluid flow moves from bottom to top. For ease of maintenance, the measuring tube 1 (Fig. 1) consists of two parts connected by flanges 5, between which the measuring capsule is fixed to the mounting flange 6. The length of the pipe 1 should be at least l ₁ = 10d in front of the capsule and at least l ₂ = 5d after the capsule, so that the fluid moves in a laminar flow, without turbulent fluctuations that can cause pressure pulsations and distort readings. For smooth fluid flow around the measuring capsule, spherical fairings are used - front 2 and rear 7.

The proposed device is simple in design, convenient and reliable to use, allows you to measure the viscosity and density of the liquid continuously, throughout the entire process in a wide temperature range.

Thus, the task is solved.

Claims (3)

1. Udnivipzhvtsivvltit vksuik from chkss nvpkntprikszk ornvss addnvpn vsrt zhsspok attiprvvdpmU poipn 2. Upp 1, from chzchkizosf 3. Upp 1, ht critical pixel ₁ = 10d inl ₂ = 5d peak

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