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6.
Ziyodullaev M. Z. Analysis and improvement of departmental
normative legal acts regulating the activities of Internal Affairs bodies for
the protection of public order and security // actual issues of protection of
public order and ensuring the safety of citizens: Rep. scientific and practical
conf. mat. - T., 2015. - P. 39.
7.
Khojakulov S. B. Improving the general prevention of offenses:
Monograph. - T.: Academy of the Ministry of internal Affairs of the Republic
of Uzbekistan, 2019. - 31 p.
Shamuratov Jamshidbek and Masharipov Bahtiyor, Masters of Tashkent
State Technology University, Uzbekistan
METHODS AND MEANS OF MEASUREMENT OF HUMIDITY OF OIL
J. Shamuratov, B. Masharipov
Abstract: The article provides an overview of the methods and techniques
for measuring oil moisture content. Thus, more information is given to Dina-
Starka, dielectric, optical and electrical techniques. The above methods are
covered in detail and there are conclusions and points about the advantages and
disadvantages of the mass.
Keywords:
direct methods, indirect methods, Dean-Stark method,
conductometric method, mass fraction of moisture.
Water in oil can be in three forms: dissolved, dispersed and free. The
content of dissolved water mainly depends on the chemical composition of
oil, oil products and temperature. With increasing temperature, the
solubility of water increases in all hydrocarbons. Methods for determining
water in oil and petroleum products can be divided into two groups:
qualitative and quantitative.
Method for determination of water content (Dean-Stark method)
The essence of the method is to distill the mixture of the test sample of
oil and solvent, which is not miscible with water, and measure the volume
of water condensed in a Dean-Stark trap. [1]
The conductometric method is based on the dependence of the
conductivity of the material on its moisture content.
Pure water has a relatively low electrical conductivity (electrical
resistivity at (20 ° C, 22 â 106 Ohm â cm). But due to the dissociation of
electrolytes when they dissolve in water, the conductivity of the solution
increases by several orders of magnitude. Thus, the conductivity of a wet
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material is determined primarily electrolytes contained in the material
itself.
Moisture-containing materials that, when dry, are dielectrics with
electrical resistivity 10-15 ÷ 10-10 Ohm â cm and more, when moistened,
they become semiconductors. The electrical resistivity is reduced to 10-3 ÷
10-2 Ohm â cm.
Humidity measurement is reduced to measuring the electrical
resistance of the primary transducer. The nature of the dependence of the
electrical resistance of the primary converter on the humidity of the solid
organic material has the form shown in Fig. 3.
In this regard, the conductometric method is used for measurements of
low and medium humidity. The lower limit of measurement is limited by the
difficulties of measuring very large resistances. For most materials, this
corresponds to a moisture content of about 5 ... 8%.
Fig. 1. The nature of the dependence of the electrical resistance of a solid
material on moisture: W is the mass fraction of moisture; lgR - electrical
resistance of the primary converter, Ohm
At low and medium humidity, a sharp dependence of resistance on
humidity appears, which ensures high sensitivity of the moisture meter in
this humidity range. With high humidity, sensitivity decreases. Therefore,
factors not related to the moisture content of the analyte (chemical
composition, structure, etc.) influence the measurement result.
In non-aqueous liquids, the dependence of the electrical conductivity in
a narrow range can be almost linear.
The electrical conductivity of wet materials, as mentioned above, is
determined by the content of electrolytes in them, which, when dissolved in
water, decay into ions. Electrolytes are conductors of an electric current of
the second kind. The passage of electric current is determined by the
movement of ions and is accompanied by chemical reactions - electrolysis.
In this case, a change in the potential of the electrodes occurs - polarization.
To eliminate the effect of polarization on the measurement result, in most
cases, the resistance measurement is carried out on alternating current.
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The conductivity of materials is greatly influenced by temperature.
Therefore, in the means of measuring the humidity of materials should be
provided for temperature compensation or stabilization of the temperature
of the analyzed materials [2].
The dielcometric (capacitive) method is based on the special electrical
properties of water. Water has a number of structural features and
properties that distinguish it from other substances. One of the abnormal
properties of water is a very high dielectric constant. The dielectric constant
of free water is ~ 80. For most solids ε <10, for liquids ε <10 ÷ 20. The
dielectric constant of water depends on its state. When bonded, water loses
its mobility in an electric field, and its dielectric constant decreases. For
chemically bound water, ε = 4.5 ÷ 4.9.
Wet material can conditionally be represented as a two-component
mixture with a dielectric constant ε_cm, which is determined by the
expression
ð
Ñм
= ð
в
ð
в
+ ð
Ñ
ð
Ñ
where ε_vi ε_c is the dielectric constant of water and dry material;
Ï_в and Ï_Ñ â volumetric concentration of water and dry material.
The dependence of the dielectric constant of some solid materials on
moisture is shown in Fig. 4.
The primary transducer of the dielcometric moisture meter is a
capacitor. The capacity of the capacitor C depends on the dielectric constant
of the substance located between the electrodes of the capacitor:
С = ðð
where ε is the dielectric constant of the analyte; k is a constant
coefficient, which is determined by the size of the capacitor and its design.
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Fig. 2. The dependence of the dielectric constant of the material ε on its
moisture content:
1 - sand; 2 - coal; 3 - grain; W - mass fraction of moisture.
Many instruments measure the impedance of a primary transformer
with alternating current. Therefore, the method is called dielcometric, and
not capacitive.
The design of the primary measuring transducers of electric moisture
meters depends on the properties of the analyzed material. The primary
transducers for liquids are similar in design to the primary transducers of
conductometers. Primary converters are cylindrical, flat and with an
external field.
Converters with an external field are made in the form of a vessel or a
piece of pipe made of a dielectric, on the outer surface of which electrodes
are placed.
When determining the moisture content of oil or oil products for
continuous sampling, the flow branch through the samples is branched or
the entire stream is passed through a primary transducer installed in a
vertical pipeline. To reduce the error caused by the deposition of paraffin
and mechanical impurities on the parts of the primary converter, the
electrodes should be placed vertically and have a protective coating [3].
Recommended installation schemes for primary converters of
dielcometric hydrometers of oil and oil products in accordance with GOST
14203-69 âOil and oil products. The dielcometric method for determining
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79
moisture âis shown in Fig. five.
Fig. 3. The location of the primary transducer dielcometric
oil moisture meter in the pipeline:
a - with cylindrical electrodes; b - with flat electrodes;
1 - internal electrode; 2 - external electrode; 3 - connector
for connection to the measuring unit [4].
Optical methods are based on the ability of water to absorb radiation of
specific wavelengths. In hydrometers, the predominantly short-wavelength
region of infrared radiation (A = 0.8 ÷ 3 μm) is used.
When measuring the humidity of liquid media, the dependence of
optical density on moisture concentration is used. The attenuation of the
radiation transmitted through the cell with the analyte is measured. The
attenuation of radiation when passing through a cuvette with a liquid
containing water mainly obeys the Bouguer-Lambert-Vera law. The method
has a high sensitivity; it is used to measure micro-concentrations of
moisture (0 ÷ 100rrM). The upper limit of applicability of the method is 10â
20%.
Infrared moisture meters for solids work on the principle of absorption
or reflection. Absorption moisture meters are used for thin sheet materials
that are transparent to infrared rays, such as paper.
Reflection moisture meters are based on the dependence of the energy
of reflected radiation of various wavelengths on the moisture content of a
substance. Moisture meters are used that use the dependence of the ratio of
the intensity of reflected radiation at wavelengths X = 1.96 μm and A = 1.75
μm.
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The lack of reflection hydrometers is obvious; only the surface layer of
the material is measured as moisture.
Visible optical moisture meters are rarely used. They are based on the
ability of some materials to change their color and reflectivity from moisture
[5].
Thus, the method of determining the moisture content of oils, based on
the principle of the dielectric coefficient, is not inferior in accuracy to the
standard method of Dean and Stark and at the same time has a number of
significant advantages.
References:
1. Berliner M. A. Measurement of humidity. M.: Energy, 1973 400 p.
2. Oil disperse systems /, Ë M.: Chemistry, 1990.226 p.
3. Krichevsky E.S., Benzar V.K., Venediktov M.V. and others / Under the
general. Ed. E.S. Krichevsky. "Theory and practice of rapid control of
humidity of solid and liquid materials." M.: "Energy", 1980, 240 p.
4. GOST 14203-69 âOil and petroleum products. The dielcometric
method for determining moisture. "
5. Mukhitdinov M.M. "Optical methods and humidity control devices."
M.: Energoatomizdat, 1986. 96 s
6. GOST 2477-65. âOil and oil products. Method for determination of
water content. "
Turdimukhammad Rakhmonov, Sherzod Kamilov, Shoolim Salimov
Military technical Institute of the National Guard of the Republic of
Uzbekistan
ABOUT SOLAR ENERGY CONVERTERS AS ALTERNATIVE SOURCES OF
ELECTRICITY
T. Rakhmonov, Sh. Kamilov, Sh. Salimov
Abstract: The article provides an analysis of data on the state of use of
solar energy as an energy source in the Republic of Uzbekistan. At the same
time, the prospects of using optimal grapheme-based solar energy
converters are noted
Keywords: energy, ecology, energy source, converters, hydrocarbon,
grapheme, climate, useful work, solar energy.
Introduction. Alternative or non-traditional energy sources are natural
resources that can be used to generate electricity.
The use of non-traditional and renewable energy sources (RES) in the
fuel and energy industry is an urgent task of the world energy industry. One