RU142684U1 - HYDROSTATIC AREOMETER - Google Patents

Abstract

The utility model relates to devices and instruments for measuring the density of a liquid. It consists of immersion and measuring parts hermetically connected to each other. The measuring part is made in the form of a U-shaped tube and contains a reference fluid with a known density. The submersible cylindrical part has a larger diameter than the U-shaped tube so that a more viscous measured fluid can freely flow into it. The hydrometer is made of transparent unbreakable material and equipped with measuring scales. Using a tripod, the immersion part of the hydrometer is lowered into the vessel with the test liquid, and its density is determined taking into account the measured differences in the levels of the reference liquid in the knees of the measuring part and in the liquid levels in the vessel and located in the immersion part of the hydrometer. The hydrometer allows the on-line measurement of the density of field and process fluids directly at the fluid sampling point.

Description

The inventive utility model relates to a device for measuring the density of a liquid under field conditions and can be used in the oil industry as an express technology.

Known liquid manometer in the form of a U-shaped tube, with which the pressure in the vessel is measured by the difference in the height of the liquid in the knees of the device (Elementary textbook of physics: Textbook / Ed. By G.S. Landsberg: T. 1. - 11 ed. - M .: Nauka, Fizmatlit, 1995 .-- S. 295-296). This device is not suitable for measuring the density of the process fluid in the field. The same source of information on page 295 indicates that in communicating vessels, the heights of the columns of liquids above the section level are inversely proportional to the densities of the liquids. This tutorial does not suggest using a known position to determine the density of an unknown fluid.

A known hydrometer for measuring the density of a liquid medium, consisting of an immersion body in the form of a bell with a reference liquid and a transparent tube as a reading device (AS USSR No. 518689, publ. 25.06.76, bull. No. 23). For practical use, a hydrometer of this design has several disadvantages:

1. The shape of the bell has two cylindrical components, and it is quite difficult to manufacture and maintain, for example, when changing the reference fluid.

2. The hydrometer design lacks a convenient place for attaching it to a portable tripod in order to achieve its absolute immobility when taking readings of the measured liquid levels and the reference.

3. In the drawing shown to the description of the hydrometer, it is seen that the measuring tube 4 has a rounded, that is, a sealed end. If this is true, then additional uncertainty is introduced during the measurements, due to the lack of information about the pressure above the reference liquid in the tube.

The technical task of the utility model is to create a product that will not have the listed disadvantages, that is, the measuring product will be easier to manufacture and maintain, its immobility will be ensured when taking readings at liquid levels. The latter factor will provide higher measurement accuracy.

In the proposed utility model, the technical task is performed by the fact that the hydrometer is hydrostatic, comprising a submersible part, a measuring part and a reference fluid, so that the cylindrical submersible part is hermetically connected to a measuring part made in the form of a U-shaped tube, which in turn contains a reference fluid, the immersion part exceeds the diameter of the U-shaped tube, and at the junction of the immersion part with the measuring hydrometer is attached to a tripod. For the convenience of taking level readings, the hydrometer is made of transparent unbreakable material, and the immersion and measuring parts are equipped with measuring scales. Fresh water is used as a reference liquid, the density of which, depending on temperature, is known and tabulated in many technical references.

The measuring device is shown in the drawing, where 1 is the immersion part, usually of a cylindrical shape, 2 is the U-shaped measuring part, 3 is the reference liquid, 4 is the connecting part of the elements 1 and 2, 5 is a tripod for mounting the hydrometer at the required height, 6 and 7 - measuring scales (rulers), 8 - a transparent vessel for the measured liquid, 9 - liquid of unknown density.

The immersion part 1 has a larger diameter than the measuring part 2 due to the fact that the test liquid can have a significant viscosity, therefore, its free flow into the immersion part must be ensured.

A hydrostatic hydrometer is used as follows.

1. A technological or other liquid with an unknown density is placed in a vessel 8 (glass).

2. A hydrometer is fixed to a tripod 5 at the junction of the immersion and measuring parts. This place in the hydrometer is the center of gravity of the device and is convenient for creating a stable position of the hydrometer during measurement.

3. A reference liquid 3 with known density, for example fresh water, is placed in the measuring part 2.

4. The submersible part 1 of the hydrometer is gently lowered into a vessel with the investigated liquid 9 using a tripod, observing the behavior of the reference water in the measuring U-shaped part so that the reference liquid does not reach the open top and does not overflow.

The measured liquid will enter the immersion part and due to the hydraulic lock of the reference liquid 3 in the U-shaped measuring part, compressed air with excess pressure P is formed between the liquid in the immersion part 1 and the reference liquid P. On the one hand, this pressure is determined by the difference in the levels of h _{1 of the} measured liquid in the vessel 8 and in submersible part 1:

On the other hand, the pressure Ρ can also be found by the height difference h _{2 of the} reference fluid 3 in different bends of the U shaped measuring part 2:

From the equality of expressions 1 and 2 we have:

5. Using measuring scales 6 and 7, determine the values of h ₁ and h ₂ and by formula 3 find the density of the liquid in the vessel 8.

Let us consider the measurement accuracy of this hydrometer using the example of measuring the density of fresh water. Fresh water is also used as a reference liquid, the density of which is known and tabulated for different temperatures and can be additionally checked using a standard float hydrometer. So for a measurement temperature of 20 ° C, the density of the reference liquid in the measuring part of the hydrometer is ρ _et.zh = 998 kg / m ³ . During the measurements, the following data were obtained:

h ₁ = 152 mm (the difference in the height of the water in the vessel 8 and the measuring part of the hydrometer);

h ₂ = 152 mm (the difference in water height measuring part hydrometer).

By formula 3 we find the density of the measured water:

ρ _W = ρ _fl.h · h ₂ / h ₁ = 998 · _152/152 = 998 kg / m ³ .

The relative measurement error is determined by the accuracy of the linear measurements made by the difference in heights h ₁ and h ₂ . Based on the experience with the claimed hydrometer and generally accepted standards, this accuracy is determined by the division price of the standard line, namely Δx = 1.0 mm. In the above example, the relative measurement error is equal to:

ξ = 100% · 2 · Δx / (h ₁ + h ₂ ) = 100% · 2 · 1 mm / (152 mm + 152 mm) = 0.66%.

This measurement accuracy is satisfactory for field operating conditions and repair work in oil wells, pipelines and tanks. An additional advantage of the proposed hydrometer is that it can be used to measure the density of a small value. For example, oil and gas companies often use Nefras C2 80/120 petroleum solvent, the density of which at 20 ° C is regulated by the manufacturer according to TU 38.401-67-108-92 as follows:

- no more than 700 kg / m ³ - for the premium;

- no more than 730 kg / m ³ - for the first grade.

Standard Series hydrometer float starts with 750 kg / m ^3, and the determination of the density of such light liquid gravimetrically using a pycnometer is only possible in the laboratory.

Using a hydrostatic hydrometer to determine the density of Nefras C2 80/120 at 20 ° C and fresh water as a reference liquid, the following data were obtained:

Table - density determination of Nefras C2 80/120 at 20 ° C using a hydrostatic hydrometer Parameter Measurement serial number Average value one 2 3 The density of the reference fluid, kg / m ³ 998 998 998 - h ₁ mm (solvent) 105.0 94.0 120.0 - h ₂ mm (reference liquid) 74.0 66.0 84.5 - Density Nefras C2 80/120 703.4 700,7 702.8 702.5

The solvent density measured under field conditions is used on an operational basis for carrying out technological calculations, in particular, for assessing the residual dissolving ability of a reagent after washing off a certain fraction of asphalt tar and paraffin deposits from oilfield equipment.

The device solves the technical problem - under field conditions, the density of liquids is estimated in a wide range with an acceptable error.

Claims (2)

1. The hydrostatic hydrometer comprising a submersible part, a measuring part and a reference fluid is configured so that the cylindrical submersible part is hermetically connected to a measuring part made in the form of a U-shaped tube, which in turn contains a reference fluid, the submersible part being larger than the U-shaped tube, and at the junction of the immersion with the measuring hydrometer is attached to a tripod. 2. The hydrometer according to claim 1, characterized in that for the convenience of taking readings of the levels, the immersion and measuring parts are made of transparent unbreakable material and are equipped with measuring scales.

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