RU2792540C1 - Method for determining weight of marine diesel, water and residue released during the settling of off-spec fuel oil with a deemulsifier - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: methods for controlling the quality of fuels, in particular to assessing the suitability of marine diesel for quality restoration at fuel depots and fuel and lubricant storages. The method is implemented by determining the weight of fuel oil, the quality of which is planned to be restored by settling when heated with a deemulsifier, taking a representative sample from it, separating 198 g from it and heating this sample to 65°C, adding 2 g of a 5% solution of an oil-soluble deemulsifier in distillate fuel to the specified sample, mixing and settling the resulting mixture in a measuring cylinder while maintaining its heating temperature, taking a sample weighing 50±2 g from the upper layer of the mixture in the cylinder after 2 hours and four more samples weighing 30±2 g after 4 hours of settling the mixture in the cylinder to determine the content of water and mechanical impurities in the indicated samples, as well as the volume of free water released in the lower layer of the mixture in the cylinder, and calculating the mass of marine diesel, which can be obtained from the available weight of off-spec fuel oil, the water weight that can be separated from off-spec fuel oil during its settling with a deemulsifier and the weight of the residue released during settling of off-spec fuel oil with a deemulsifier.

EFFECT: increasing the reliability of determining the weight of marine diesel, water and residue when planning operations to restore the quality of off-spec fuel oil for assessment of their economic efficiency and feasibility.

1 cl, 8 dwg, 2 tbl, 1 ex

Description

The invention relates to methods for controlling the quality of fuels, in particular to assessing the suitability of marine fuel oil for quality restoration at fuel depots and warehouses of fuels and lubricants.

Navy fuel oil is used on ships of the Navy with boiler-turbine power plants (KTEU) (1 - Internet resource: http://www.mil.ru, accessed 03/09/2020) and in stationary boiler houses that place high demands on the quality of the fuel used. The main brand of naval fuel oil produced in Russia is marine fuel oil F5 in accordance with GOST 10585 (2 - GOST 10585-2013. Petroleum fuel. Fuel oil. Specifications).

Many years of experience in the use of marine fuel oil has shown that one of the main problems of its use is an increase in the content of water and mechanical impurities during its storage in fuel and lubricant depots and use in the fuel system of ships (vessels) (3 - Fakhrutdinov M.I., Nelyubov D.V. Problems and prospects for the use of naval fuel oil in boiler-turbine power plants of ships of the Navy / Abstracts of the Interdepartmental Scientific and Technical Conference "55 Years of Chemmotology - the main results and directions of development" / Edited by V. V. Sereda, N. N. Grishin . - M.: Printleto, 2019. - 352 pp., pp. 134-137). The specified pollution of marine fuel oil leads to a deterioration in the following quality indicators provided for by GOST 10585: mass fraction of water, mass fraction of mechanical impurities, kinematic viscosity (conditional), ash content, density, which is a sign of low stability of the quality of fuel oil, other operational properties are negatively affected (according to GOST 4.25-83 (4 - GOST 4.25-83 System of indicators of product quality. Petroleum liquid fuels. Nomenclature of indicators): pumpability, flammability, combustibility and tendency to high-temperature deposits.

Over the past three decades, the quality of naval fuel oil produced by domestic enterprises has changed significantly. Residual products of secondary oil refining and petrochemistry, which are not allowed for use by the requirements of GOST 10585, significantly worsen the ability of fuel oil to separate water and mechanical impurities during settling, began to be massively involved. Thus, the use of a known method for restoring the quality of marine fuel oil (by heating it to 70 ° C and settling) does not always ensure the restoration of its quality to the requirements of GOST 10585. At the same time, the costs of heating and maintaining the temperature of 1000 tons of off-standard marine fuel oil in a vertical steel tank in the warm season for 2 hours to separate water and mechanical impurities amount to more than 5 million rubles, which indicates the risk of significant financial losses with a negative result of restoring the quality of fuel oil.

In connection with the above, the authors were faced with the task of developing a method for determining the mass of marine fuel oil, water and residue released during the settling of substandard fuel oil with a demulsifier, which would meet the following requirements:

- should increase the reliability of determining the mass of marine fuel oil, water and residue released during the settling of substandard fuel oil with a demulsifier by using a sample of fuel oil to be settled when determining the specified parameters;

- the implementation of the method should be possible with the use of common laboratory equipment and simulation of the process of settling substandard fuel oil with a demulsifier in the conditions of warehouses of fuels and lubricants and tank farms;

- the method should provide for the implementation of the process of settling substandard fuel oil with a demulsifier in the conditions of fuel depots and tank farms.

The analysis of patent and scientific and technical information in this area made it possible to identify technical solutions that partially meet the above requirements.

A known method for determining the mass of products of the process of disposal of oil sludge and oil-contaminated soils (6 - Nelyubov D.V., Vazhenin D.A., Golubev E.V., Kudryavtsev N.N. Installation for the disposal of oil sludge and oil-contaminated soils / Oil. Gas. Innovations 2014. No. 6. S. 63-68.), which consists in the sequential mixing of oil sludge with nefras, separation of mechanical impurities from oil sludge, heating and pyrolysis of the resulting mixture, its fractionation and separation of commercial pyrolysis oil at the plant, with a feedstock capacity of - 30 kg/h and calculation according to the obtained experimental data of the ratio of masses and mass fractions of raw materials, main and by-products.

The disadvantage of this method is the need to use unique equipment for the implementation of this process (pilot plant with a capacity of 30 kg/h), which does not allow it to be implemented using standard laboratory equipment.

A known method of thermal dehydration of fuel oil (7 - patent of the Russian Federation No. RU 2127298. Appl. 06/27/1997), which involves heating fuel oil using heaters with a surface temperature of 150-190 ° C and thermostating it until the water content requirements established by regulatory documentation are reached. This method can be implemented in warehouses of fuels and lubricants and oil depots.

The disadvantages of this method are the high cost of estimating the mass released during the restoration of the quality of marine fuel oil due to the need to heat the entire volume of substandard fuel oil in the tank field (Savchenkov A.L. Chemical technology of field oil preparation: textbook / A.L. Savchenkov. - Tyumen: Tyumen State Oil and Gas University, 2011. P. 130-132.), which includes determining the mass fraction of water in oil in a known way, determination by available production data (of another field) of the mass fraction of water in the dehydrated oil and the mass fraction of oil in the separated water and the calculation of the masses of water and oil from the obtained data before and after their separation in the settling process.

The disadvantage of this method is its low reliability due to the fact that the determination of the mass fractions of separated water and oil is carried out on the basis of theoretical concepts of the rate of settling of water droplets in oil and production data of another field, while the efficiency of water separation from fuel oil by the same method can vary many times, which is associated with the heterogeneity of the composition of fuel oil and the different efficiency of chemical reagents used for its dehydration.

The technical result of the invention is to increase the reliability of determining the masses of naval fuel oil, water and residue released during the settling of substandard fuel oil when heated with a demulsifier.

The specified technical result is achieved by the fact that in the known method for determining the masses of marine fuel oil, water and residue released during the settling of substandard fuel oil with a demulsifier, including determining the mass of substandard fuel oil (M _noncond ), according to the invention, the efficiency of settling substandard fuel oil with a demulsifier is preliminarily evaluated for then a representative sample is taken from which a sample weighing 198 g (M _m ) is taken and placed in a flask or glass with a volume of 500 cm ³ , heated to 65 ° C and 2 g of a 5% mass solution of an oil-soluble demulsifier in winter diesel fuel is added to the sample or aviation kerosene, stirred at a speed of 300 rpm while maintaining a temperature of 65 ° C for 2 hours, after which the resulting mixture is transferred for settling into a graduated cylinder with a volume of 250 cm ³ with a division value of not more than 2 cm ³ , which is sealed and thermostatted in for 2 hours at 65°C, after which the settling efficiency is evaluated, for which from the upper layer of the mixture in the measuring cylinder take a sample weighing 50 ± 2 g (m ₁ ) and determine the mass fraction of water (W ₁ ) in it: with a value of W ₁ more than 0.3% of the mass, it is concluded that the settling of substandard fuel oil with a demulsifier is ineffective and it is impossible to isolate water and residue from it, and if the mass fraction of water is less than or equal to 0.3%, the remaining part of the mixture in the measuring cylinder continues to be thermostated at 65 ° C for another 2 hours, after which the volume of released water in the lower part of the cylinder is determined ( V _in ), and from the upper layer of the mixture in the cylinder 4 samples are sequentially taken weighing 30 ± 2 g (m ₂ , m ₃ , m ₄ , m ₅ ), each of which is divided into a smaller part - 10 g and a large part - the remainder , in each larger part, the mass fraction of water is determined (W ₂ , W ₃ , W ₄ , W ₅ ) and these values \u200b\u200bare compared with the norm, not more than 0.3% of the mass, and in a smaller part of the sample where the maximum water content is set, corresponding to the specified norm, determine the mass fraction of mechanical impurities, etc. and its value is not more than 0.1% of the mass, the mass of naval fuel oil is calculated, which can be separated from the available mass of substandard fuel oil:

where M _maz is the mass of naval fuel oil, which can be obtained from the available mass of substandard fuel oil, t;

M _noncond - mass of substandard fuel oil, t;

C - mass fraction of a sample of substandard fuel oil in a mixture with a demulsifier solution (0.99), units;

M _p - the sum of the masses of the first sample of fuel oil (m ₁ ) and all subsequent samples (m ₂ , m ₃ , m ₄ , m ₅ ), with a mass fraction of water, not more than 0.3% of the mass and a mass fraction of mechanical impurities, more than 0 .1% mass, g;

M _m - weight of sample of substandard fuel oil, g;

when the mass fraction of mechanical impurities is more than 0.1% of the mass, formula (1) is used to determine M _maz with the difference that when determining M _p , the sum of the masses of all previous samples of the one in which the mass fraction of mechanical impurities was determined is used, after which the mass of water is calculated , which can be isolated from substandard fuel oil during its settling with a demulsifier

where M _water is the mass of water that can be separated from substandard fuel oil during its settling with a demulsifier, t;

V _in - the volume of water released during settling in a graduated cylinder, cm ³ ;

ρ - water density is taken equal to 1 g/cm ³ ;

according to the data obtained, the mass of the residue released during the settling of substandard fuel oil with a demulsifier is determined:

where M _rest. - the mass of the residue released during the settling of substandard fuel oil with a demulsifier, i.e.

The essence of the method consists in laboratory modeling of heating processes, mixing substandard fuel oil with a demulsifier solution and settling from non-water and mechanical impurities, followed by determining the amount of fuel oil in which the mass fraction of water and mechanical impurities corresponds to the established norm.

In FIG. Figure 1 shows the dependences of the mass fraction of water in the first (m ₁ - points with marker 1) and the second sample (m ₂ - points with marker 2) of substandard fuel oil during the settling of its representative sample extracted from the VZHBR-5000 tank of the fuel and lubricants warehouse (mass fraction of water in a sample of 13.6% of the mass), in a measuring cylinder when heated from the concentration of the demulsifier mixed with it after heating the solution of the demulsifier in the TS-1 fuel;

fig. Figure 2 shows the dependences of the mass fraction of water in the first (m ₁ - points with marker 1) and the second sample (m ₂ - points with marker 2) of substandard fuel oil during the settling of its representative sample extracted from the VZHBR-5000 tank of the fuel and lubricants warehouse (mass fraction of water in a sample of 13.6% of the mass), in a measuring cylinder when heated from temperature;

fig. Figure 3 shows a comparison diagram of the effectiveness of demulsifiers in terms of the mass fraction (in %) of removed water during settling for 4 hours in a measuring cylinder of a representative sample of substandard fuel oil extracted from the VZHBR-5000 tank of the fuel and lubricants warehouse (mass fraction of water in the sample is 13.6% of the mass), marker signatures: 1 - TND demulsifier, 2 - Separol DR 50 demulsifier, 3 - INTEX-1018A demulsifier, 4 - TND-NT demulsifier, 5 - Dissolvan 2830;

fig. Figure 4 shows the dependence of the mass fraction of samples taken along the height of the cylinder when settling a mixture of substandard fuel oil with a demulsifier solution in a measuring cylinder when heated on the mass fraction of water in the samples taken, marker signatures: 1 - fuel oil from VZhBR-500 of the fuel and lubricants warehouse, 2 - fuel oil from a fuel tank ship, 3 - fuel oil from VZHBR-600 fuel depot, 4 - fuel oil from VZHBR-250 fuel depot, 5 - substandard fuel oil from Deltamet LLC;

fig. Figure 5 shows the dependence of the mass fraction of naval fuel oil (C) released during the settling of substandard fuel oil of various origins with a demulsifier solution in a measuring cylinder when heated, marker signatures: 1 - fuel oil from VZhBR-5000 of the fuel and lubricants warehouse, 2 - fuel oil from the ship's fuel tank, 3 - fuel oil from VZhBR-500 fuel depot, 4 - fuel oil from VZHBR-250 fuel depot, 5 - fuel oil from VZHBR-600 fuel depot;

fig. 6 shows the dependence of the volume of released water in the lower part of the cylinder (V _in ) on the time of mixing substandard fuel oil with a demulsifier solution in TS-1, marker signatures: 1-2 hours of settling; 2-4 hours of settling;

fig. 7 shows the dependence of the mass fraction of samples taken along the height of the cylinder on the water content in them when using various demulsifier solvents according to the method, marker signatures: 1-2 hours of settling; 2-4 hours of settling;

fig. 8 shows an example of determining the volume of released water in the lower part of the cylinder V _in (2 cm ³ ) from a mixture of substandard fuel oil with a demulsifier solution, according to the method in a cylinder with a volume of 250 cm ³ and a valuable division of 2 cm ³ after 4 hours of settling when heated.

The essential features of the invention are:

- Settling of substandard fuel oil with the use of demulsifiers, which provides an increased intensity of separation of water from fuel oil. The need to use demulsifiers is substantiated by the results of comparing the efficiency of water separation during settling with heating samples of marine fuel oil from the fuel tank of a ship (mass fraction of water 1.2%) and from a reinforced concrete buried tank with a capacity of 5000 m ³ of a fuel and lubricants warehouse (mass fraction of water 13.6 %). After 4 hours of settling with heating to 70°C, the mass fraction of water in the upper layer of these samples was 0.58% and 2.32%, respectively, which indicates the low efficiency of this method of removing water from fuel oil. The results of studies of a similar settling process with the addition of a demulsifier TND (TU 20.59.42.140-001-01564816-2018 "TND" reagent. Specifications http://nt-tek.ru/tnd. (Accessed 02.02.2021) showed the possibility of removing of water by sedimentation at 65°C of substandard fuel oil of fleet F5 with a demulsifier.The mass fraction of water in the upper layer of fuel oil after settling was from 0.15% wt. to 0.20% wt. at a concentration of demulsifier in fuel oil from 0.045% wt. to 0.085% mass (Fig. 1);

- temperature of heating and temperature control of flooded fuel oil 65°C was determined on the basis of experimental data on the water content in its upper layer after settling with the TND demulsifier (TU 20.59.42.140-001-01564816-2018 "TND" reagent. Specifications http:// nt-tek.ru/tnd (Accessed 02.02.2021) at a concentration of 0.05 wt % in the temperature range from 65°С to 75°С (Fig. 2).It is shown that the required value of the mass fraction of water (not more than 0.3% wt.) is achieved at a fuel oil heating temperature of at least 65°C;

- the grades of demulsifiers suitable for use in the process of separating water from fuel oil were determined based on data on their effectiveness in relation to substandard fuel oil from a reinforced concrete buried tank with a capacity of 5000 m ³ of a fuel and lubricants warehouse (mass fraction of water 13.6%) (Fig. 3 ), which are: TND according to TU 20.59.42.140-001-01564816-2018, Separol DR50 according to TU 2458-007-17635211-2013, INTEX - 1018A according to TU 2458-010-40666476-2003;

- the time of mixing substandard fuel oil with a demulsifier solution - 2 hours was determined by the results of determining the volume of released water during the settling of substandard fuel oil, depending on the time of its mixing with a demulsifier solution (Fig. 6). It is shown that this dependence is logarithmic with a high accuracy of approximation, which indicates that with an increase in mixing time of more than 2 hours, the volume of water released will not increase;

- the possibility of determining the mass fraction of marine fuel oil, which can be obtained from the available mass of substandard fuel oil (M _mazut ) by changing the mass fraction of water in the mixture of fuel oil with a demulsifier solution along the height of the cylinder, is established on the basis of data on the distribution of water content in samples along the height of the cylinder during settling with a demulsifier of substandard fuel oils of various origins (Fig. 4) - the mass fraction of standard fuel oil of the fleet, isolated from substandard fuel oil during tests in a cylinder (Fig. 5);

- a correlation was established between the dynamics of the separation of water and mechanical impurities during the settling of substandard fuel oil (Table 1). It is shown that the separation of mechanical impurities during the sedimentation of fuel oil occurs more intensively than the separation of water. This made it possible, when assessing the mass fractions of components separated from substandard fuel oil, to perform a single determination of the mass fraction of mechanical impurities only once:

- Solvents suitable for use in the preparation of a demulsifier solution were determined based on the results of settling substandard fuel oil with a demulsifier dissolved in it (Fig. 7), which are the winter diesel fuel fraction and TS-1 fuel.

Thus, the determined values of the masses of naval fuel oil, water and residue, isolated from substandard fuel oil, meet the requirements for the claimed method.

The method is implemented as follows

To substantiate the set of features of the claimed method, the masses of marine fuel oil, water and residue were determined, which can be isolated during the settling of 5 samples of substandard fuel oil of various quality and origin (table 2), selected from batches weighing 1000 tons each.

The data in Table 2 indicate that in order to estimate the masses of marine fuel oil, water and residue that can be isolated from substandard fuel oil by settling it with a demulsifier, it is necessary to test each sample of fuel oil according to the method, due to the fact that the values of these masses are determined by the characteristics of the chemical and phase composition of fuel oil, the effect of which on the process of sedimentation of water and mechanical impurities cannot be adequately assessed without modeling.

Example. It is necessary to determine the masses of marine fuel oil, water and residue, which can be obtained by settling substandard fuel oil with a demulsifier.

Requirements for the quality of marine fuel oil in terms of "mass fraction of water", no more than 0.3% of mass, in terms of "mass fraction of mechanical impurities", no more than 0.1% of mass. The density of substandard fuel oil is 923 kg/m ³ . The restoration of quality is planned at the fuel and lubricants warehouse in a reinforced concrete buried tank RVZHB-2000 with a nominal capacity of 2000 m ³ . Fuel oil temperature 15°C.

A combined sample of the specified fuel oil with a volume of 2.5 l according to GOST 2517 was taken. In the specified sample, the mass fraction of water was determined in a known way - 10 wt% and the mass fraction of mechanical impurities in a known way - 0.5 wt%.

The mass of substandard fuel oil in the tank was determined in a known manner according to the calibration tables of the tank based on data on its filling height and density. The mass of substandard fuel oil M _non-cond = 1000 tons.

To assess the effectiveness of settling substandard fuel oil with a demulsifier, a sample weighing 198 g was separated from the sample, which was placed in a flat-bottomed flask with a volume of 500 ml. The weighed flask was heated in an air thermostat to 65°C.

Prepared 5% of the mass. a solution of an oil-soluble demulsifier in TS-1 fuel (as a variant of TND according to TU 20.59.42.140-001-01564816-2018) by a known method.

2 g of the indicated solution was added to a flask heated to 65°C with a weighed amount of fuel oil, and while maintaining the temperature of the resulting mixture from 63°C to 67°C, the indicated mixture was stirred at a speed of 300 rpm for 2 hours.

After mixing, the mixture was poured into a graduated cylinder with a volume of 250 cm ³ with a division price of 2 cm ³ . The cylinder was closed with a cork (as an option) and thermostated at 65°C for 2 h, after which it was removed from the thermostat.

To assess the effectiveness of settling substandard fuel oil with a demulsifier from the top layer of the mixture in the cylinder using a glass pipette with a volume of 100 ml and scales (as an option), one sample weighing 52 g (m ₁ ) was taken, in which the mass fraction of water was determined by a known method W ₁ =0 .29%. Received a value of 0.29% of the mass, which indicates the effectiveness of settling.

The cylinder, immediately after sampling from the upper layer of the mixture, was placed back into an air thermostat for its temperature control for another 2 hours at a temperature of 65°C, after which it was removed and the volume of released water in the bottom layer was fixed V _in = 5 cm ³ (as shown in Fig. 8).

From the upper layer of the mixture in the cylinder, 4 samples were sequentially taken weighing 29 g - m ₂ , 28.5 g - m ₃ , 30 g - m ₄ , 32 g - m ₅ .

Each selected sample was divided into a smaller part of 10 g - to determine the mass fraction of mechanical impurities and a large part, the rest of the mass - to determine the mass fraction of water.

The mass fraction of water in most of these samples was W ₂ =0.18% mass, W ₃ =0.23% mass, W ₄ =0.30% mass, W ₅ =1.28% mass. Since the mass fraction of water corresponds to the norm (no more than 0.3% of the mass) and is closest to it in the sample m ₄ , then in the previously isolated 10 g of this sample, the mass fraction of mechanical impurities was determined, which amounted to 0.03% and corresponds to the norm (not more than 0.1%).

Тогда массу мазута флотского, которая может быть получена из имеющейся массы некондиционного мазута определили по формуле (1):Thus, the sum of the masses of the first fuel oil sample (m ₁ ) and all subsequent samples (m ₁ , m ₂ , m ₃ , m ₄ ) with a mass fraction of water not more than 0.3% of the mass and a mass fraction of mechanical impurities not more than 0.1 % mass determined: M _p =52+29+28.5+30+32.5=172 g.

Then the mass of naval fuel oil, which can be obtained from the available mass of substandard fuel oil, was determined by the formula (1):

The mass of water released from substandard fuel oil during its settling with a demulsifier was calculated, assuming the density of water (ρ) equal to 1 g/cm ³ , according to the formula (2):

Based on the data obtained, we determined the mass of the residue released during the settling of substandard fuel oil with a demulsifier according to the formula (3):

Conclusion: out of 1000 tons of substandard fuel oil stored in a vertical steel tank with a volume of 2000 m ³ in the fuel and lubricants warehouse, when it is settled with a demulsifier, according to the method, 860 tons of naval fuel oil, 25.2 tons of water and 114.8 tons of residue can be isolated.

An increase in the reliability of determining the masses of marine fuel oil, water and residue released during the settling of substandard fuel oil with a demulsifier is provided by laboratory modeling of the separation of these components from substandard fuel oil.

The application of the invention will allow, due to a combination of essential features that simulate the process of settling substandard fuel oil with a demulsifier, to increase the reliability of determining the masses of naval fuel oil, water and residue when planning operations to restore the quality of substandard fuel oil;

the values of the masses of marine fuel oil, water and residue obtained according to the method make it possible to increase the accuracy of the economic assessment of the efficiency of restoring the quality of marine fuel oil, which makes it possible to reduce the risks of financial losses in cases where residual products of secondary oil refining and petrochemical products are used in the composition of fuel oil, which adversely affect its the ability to separate water and mechanical impurities during settling with heating.

Claims (15)

A method for determining the masses of marine fuel oil, water and residue released during the settling of substandard fuel oil with a demulsifier, including determining the mass of substandard fuel oil (M _noncond ), characterized in that the efficiency of settling substandard fuel oil with a demulsifier is preliminarily assessed, for which its representative sample is taken, from which a sample weighing 198 g (M _m ) is taken and placed in a flask or glass with a volume of 500 cm ³ , heated to 65 ± 2 ° C and 2 g of a 5 wt.% solution of an oil-soluble demulsifier in winter diesel fuel or aviation kerosene is added to the sample, mixed with at a speed of 300 rpm while maintaining a temperature of 65±2°C for 2 hours, after which the resulting mixture is transferred for settling into a graduated cylinder with a volume of 250 cm ³ with a division value of not more than 2 cm ³ , which is sealed and thermostatted for 2 hours at 65 ± 2 ° C, after which the effectiveness of settling is evaluated, for which a sample weighing 50 ± 2 g (m ₁ ) and determine the mass fraction of water in it (W ₁ ): with a value of W ₁ more than 0.3 wt.%, it is concluded that the settling of substandard fuel oil with a demulsifier is ineffective and the impossibility of separating water and residue from it, and with the value of the mass fraction water less than or equal to 0.3%, the rest of the mixture in the measuring cylinder continues to be thermostated at 65±2°C for another 2 hours, after which the volume of released water is determined in the lower part of the cylinder (V _in ), and from the upper layer of the mixture in the cylinder sequentially 4 samples are taken weighing 30 ± 2 g (m ₂ , m ₃ , m ₄ , m ₅ ), each of which is divided into a smaller part - 10 g and a large part - the remainder, in each large part the mass fraction of water is determined (W ₂ , W ₃ , W ₄ , W ₅ ), compare these values with the norm, not more than 0.3 wt.%, and in a smaller part of the sample where the maximum water content corresponding to the specified norm is established, the mass fraction of mechanical impurities is determined and at its value is not more than 0.1 wt.% calculate the mass of fuel oil fl otsky, which can be isolated from the available mass of substandard fuel oil

where M _mazut is the mass of naval fuel oil, which can be obtained from the available mass of substandard fuel oil, t; M _noncond - mass of substandard fuel oil, t; M _p - the sum of the masses of the first sample of fuel oil (m ₁ ) and all subsequent samples (m ₂ , m ₃ , m ₄ , m ₅ ), with a mass fraction of water not more than 0.3 wt.% and a mass fraction of mechanical impurities more than 0, 1 wt%, g; C - mass fraction of a sample of substandard fuel oil in a mixture with a demulsifier solution (0.99), units; M _m - weight of sample of substandard fuel oil, g; when the mass fraction of mechanical impurities is more than 0.1 wt.%, formula (1) is used to determine M _maz , with the difference that when determining M _p , the sum of the masses of all previous samples of the one in which the mass fraction of mechanical impurities was determined is used, after which they calculate the mass of water that can be separated from substandard fuel oil during its settling with a demulsifier

where M _water is the mass of water that can be separated from substandard fuel oil during its settling with a demulsifier, t; V _in - the volume of water released during settling in a graduated cylinder, cm ³ ; ρ - water density is taken equal to 1 g/cm ³ ; according to the data obtained, the mass of the residue released during the settling of substandard fuel oil with a demulsifier is determined

where M _rest is the mass of the residue released during the settling of substandard fuel oil with a demulsifier, i.e.

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