RU2454661C2 - Method of predicting shelf life of hydrocarbon fuel in storage facilities - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: when predicting shelf life of fuel, an 'acidity' quality factor is used and the effect of surface area S_st of structural materials of the intended storage facilities on the volume V_st of the fuel to be stored based on conditions of the intended storage climatic regions is taken into account. The full surface area s_us of samples of structural material for temperature control is calculated; n (n≥4) batches of samples of structural materials are prepared, each being temperature-controlled at a defined temperature while collecting fuel samples and determining the current acidity value of each sample. Curves of change in acidity value of the fuel from each batch versus the duration of temperature control at given temperatures are plotted, after which the energy factor B of the analysed fuel is determined and for 1000≤B≤45000, the shelf life of the fuel in a specific storage facility and specific climatic region is determined using a formula.

EFFECT: high reliability of analysis results owing to test conditions which are close to natural storage conditions of the fuel.

2 ex, 4 tbl, 5 dwg

Description

The invention relates to methods for researching materials, in particular to assessing changes in the quality indicators of hydrocarbon rocket fuels (hereinafter referred to as fuels), according to which their shelf life is predicted, and can be used both at manufacturing plants and during the operation of fuel service equipment, when there is a need to store fuel both in storage facilities and in the fuel tanks of rocket weapons (PB).

The fuel developed according to old technologies is stored for a long time in special warehouses (bases) and in the tanks of rocket weapons, where the fuel comes into contact with various structural materials and in various climatic conditions, including at high temperatures (40-50 ° C), which leads to a change in the operational properties of the fuel. Due to the lack of production of certain brands of fuel and the replacement of stored reserves with fuel from newly accumulated batches, most of the fuel is stored significantly longer than its warranty periods (more than 2.5 times). In this regard, the requirements are increasing to most reliably determine the shelf life of fuel in storage facilities and in the refueling state in the fuel tanks of RV products. There is a need to predict the feasibility of using fuels having a shelf life above warranty. In addition, it should be borne in mind that fuel storage tanks often have various structural metal and nonmetallic materials (for example, St3 steel, AMG-6 aluminum alloy, VITUR T-2213-85 polymer, rubber compound 51-1434, etc. e.), which adversely affect the duration of the storage periods of fuel in them.

The authors were faced with the task of developing an operational and reliable method for predicting the shelf life of fuel, taking into account the diversity of its composition (the presence of additives and additives), as well as the influence of structural materials of storage facilities, operating and storage conditions.

A known method for determining the shelf life of a fuel, including keeping it in a tank chemically inert with respect to fuel and bringing the metal into contact with the fuel in the form of samples taken one at a time simultaneously with sampling the fuel, the ratio of the surface area of one sample to the volume of the fuel sample being taken as constant and equal to the ratio of the area of the inner surface of the tank to the volume of fuel contained in it. The shelf life of the fuel is judged by the time the temperature of the onset of sedimentation decreases to the standard critical value [a.s. USSR No. 1201772, G01N 33/22, 1984].

A disadvantage of the known method for determining the shelf life of fuel is the low reliability of the results due to the error in estimating the change in temperature of the onset of fuel deposition after it has been kept for a predetermined time in contact with a metal sample, since a factor determined by the design features of the proposed fuel storage means is not taken into account ( fuel tank of the product RV, the ratio of the surfaces of metallic and non-metallic materials to the volume of fuel in contact with them a) and climatic characteristics of the storage areas.

The closest in technical essence and taken as a prototype is a method for predicting acceptable shelf life of fuels by changing the information indicator - thermo-oxidative stability in dynamic conditions (STO 08151164-004-2009 Organization Standard. Method for determining thermo-oxidative stability in circulation conditions. FAA "25 State Research Institute of Chemotology of the Ministry of Defense Of Russia ”, Moscow, 2009. The MMC was approved for the use of fuels, oils, lubricants and special fluids under the State Standard of Russia (decision No. 23/1-131 dated 05/19/80)).

The essence of the known method lies in the assessment on the device TSITO-M (Z. A. Sablina, G. B. Shirokova, T. I. Ermakova. Laboratory methods for assessing the properties of motor and recreational fuels. - M .: "Chemistry", 1978 , p.105) changes in the thermo-oxidative stability of fuel samples removed with a certain frequency from the thermostat, where they are oxidized in hermetically sealed containers — 0.5 dm ³ glass bottles (4: 1 ratio of fuel to air volumes), at a temperature of 100 ° C.

The criterion for evaluating the method is the time (τ _pre , day) of preliminary oxidation of the fuel in the thermostat, after which the rate (W, ° С / h) of the temperature decrease in the lower part of the circulation circuit of the CITO-M device, proportional to the clogging speed of the pores of the control filter, reaches 10 ° C / hour. If for the initial fuel sample (without thermostating) W≥10 ° С / hour, thermostat is not held and it is considered that this fuel is not subject to long-term storage. The allowable shelf life of the fuel in the tanks (τ _xp , years) is calculated by the formula

This method, like the previous one, does not take into account the actual conditions of operation and storage of fuel, in addition, the design features of specific systems are not taken into account: the fuel tank of the RV product, the ratio of the surface of metallic and nonmetallic materials in contact with the estimated volume of stored fuel, climatic characteristics of the storage areas and operation, which leads to significant errors and low reliability in predicting acceptable shelf life of fuel.

The technical result of the invention is improving the accuracy and reliability of predicting the shelf life of fuel by bringing the test conditions closer to the natural conditions of its storage, taking into account the influence of structural materials of specific storage media and climatic characteristics of the proposed storage areas.

The specified technical result is achieved by the fact that in the known method for predicting the shelf life of fuels in storage media, including sampling hydrocarbon fuels, determining the information indicator of each sample, comparing the results with a given value according to current GOST or technical specifications for this fuel, in the absence of which carry out thermostating at a given temperature with prepared samples of structural materials in containers of a given volume, which fuel is contacted in the proposed means of storage, and subsequent measurement of storage of hydrocarbon fuels term of a mathematical function, according to the invention as an information index characteristic acidity analyte hydrocarbon fuel further define the volume V _xpn be stored hydrocarbon fuel and contacting this volume area S _hrn the surface of each structural material of the intended storage medium, on which the coefficient is calculated capacity k _i for each construction material, which is calculated using the total surface area s _isp samples of each material of construction for temperature control, prepare n batches (n≥4) structural material samples, whose total area is equal to the calculated total surface area of each structural material is carried out first thermostating batches of samples of structural materials with a sample of the analyzed fuel at a given temperature T _max less than or equal to 383 K, periodically select digging at least 10 fuel samples and determining the current values of the acidity of each sample, when the set acidity value is reached, thermostatting is stopped, the maximum thermostatting time τ _{max is} reached until the set acidity is reached, and a graphical dependence of the continuous increase of the hydrocarbon fuel acidity on the duration of thermostatting at the set temperatures is built, thermostatting of the remaining batches is carried out at temperatures whose values, including the temperature range of the first batch is a decreasing arithmetic progression with a progression difference of at least minus 5 K, during the fixed duration of the temperature control of the first batch, at least 10 fuel samples are periodically taken from each batch and the current acidity values of each sample are determined, graphical dependencies of a continuous increase in the values are constructed hydrocarbon fuel acidity for each batch in the same coordinate system as for the first batch, select two graphically Depending, thus on axis acidity values selected point 0.125 mg KOH / ^cm3 fuel, from which a line parallel to the axis of the length of incubation values intersects these two graphics according to T = 373 K and T = 363 K, for which the cross point is determined the duration of temperature control until the acidity of the analyzed hydrocarbon fuel at a selected point is equal to 0.125 mg KOH / cm ³ fuel, two different batches of fuel at different temperatures, after which the energy The analyzer of the analyzed hydrocarbon fuel according to the following relationship:

,

,

where B is the energy indicator, K;

T _n , T _{n + 1} - temperature thermostating fuel with samples of structural materials of two different parties, K;

n = 1, 2, ..., (n-1) - the number of batches of samples of structural materials;

τ _Tn , τ _{Tn + 1} - the duration of temperature control at temperatures T _n , T _{n + 1} , respectively, until the acidity of the selected value (according to the graphical dependence), hour,

and with values of 1000 В B 45 45000, the shelf life of the fuel in a specific storage medium and a specific climatic region is predicted by the following formula:

where τ _xp is the predicted shelf life of the fuel;

τ _max - the duration of temperature control of the fuel sample with the first batch of structural materials at a temperature T _max during which the acidity of the fuel reaches a predetermined value;

τ _xpj is the duration of the j-th temperature interval for one year for a specific climatic region of operation of the refueling storage device, hour;

T _max - temperature thermostating of the fuel sample with the first batch of structural materials, K;

T _j is the average temperature value of the j-th temperature range for a specific climatic region of operation of the storage medium, K;

N is the number of accepted temperature intervals in a particular climatic region of operation of the storage medium.

Figure 1 - graphical dependence of changes in the acidity values of fuel naphthyl on the duration of its storage;

figure 2 - graphical dependence of the values of the quality indicator "thermo-oxidative stability in static conditions - mass concentration of sediment in the fuel" fuel T-1C from the duration of its storage;

figure 3 - graphical dependence of the increase in acidity from the time of temperature control of samples of a sample of decilin fuel at different temperatures;

figure 4 - graphical dependence of the increase in acidity from the time of temperature control of samples of a sample of synthine fuel at different temperatures;

figure 5 - graphical dependence of changes in the acidity of fuel synthine from the shelf life in a special warehouse and the experimental data obtained by the proposed method.

The technical essence of the invention lies in the fact that the authors, having processed a large amount of statistical data on the change in the physicochemical properties of various fuels during storage under real conditions in storage media, obtained dependences of a continuous increase in acidity values on the duration of storage of fuel and the influence of structural materials of these storage means.

The quality indicator - "acidity" - in the inventive method is selected as information, since the analysis and processing of statistical data on the experimental storage of fuel shows that the value of acidity as a result of oxidation of the fuel during storage is continuously increasing in contrast to other quality indicators, the values of which vary slightly or discrete.

In addition, by studying and analyzing the data of experimental storage, the authors proved that the temperature and contact area of the fuel with the structural materials of the storage medium, as well as the duration of its storage in a specific climatic region, mainly affect the change in the quality of fuel during long-term storage.

Thermostatic temperature T _isp. choose taking into account the maximum allowable temperatures of a particular fuel and safety when working with it. To carry out temperature control, n temperatures (n≥4) are taken to increase the accuracy of estimating the temperature dependence of the continuous increase in fuel acidity on the duration of temperature control.

The maximum temperature T _max thermostating is selected 10 K below the temperature at which the effectiveness of the antioxidant additives in the fuel decreases sharply, which leads to a sharp deterioration in its quality.

The capacity coefficient k _i , which is the ratio of the surface area S _{xpн of the} surface of each structural material of the proposed fuel storage medium to the volume V _{xp of} this fuel to be stored in this storage medium, is calculated by the formula

.

.

This dependence was obtained by processing statistical data on the storage of fuel in various storage media using methods of mathematical modeling and similarity theory of complex systems.

The volume of fuel samples v _COI thermostating be one party of constructional materials with a specific test temperature set on the assumption that the fuel volume ratio to the free volume of the container for temperature to be not less than 0.9.

To carry out temperature control, n batches (n≥4) of samples of structural materials of the calculated area are taken to increase the accuracy of estimating the temperature dependence of the continuous increase in fuel acidity on the duration of temperature control.

The method is implemented as follows.

Example 1

It is necessary to forecast the shelf life of combustible decilin (TU 38.102128-86), manufactured in 1988, and stored in the fuel tank of the product RV X-55 in climatic region II ₁₀ (warm wet) (GOST 16350-80) with an average annual air temperature 287.6 K.

We determine the numerical values of the capacity coefficients k ₁ and k ₂ (there are two criteria, since combustible deciline, when stored in the product tank RV X-55, comes into contact with two types of structural materials - metal and polymer (Table 1 - materials that come into contact with fuel during storage in natural conditions in storage facilities)) for each tank material

where S _1xpn S _2xpn is the contact area of combustible decilin with one of the structural materials of the fuel tank of the product X-55, m ² ;

= 13 м²;

= 13 m ² ;

= 1,2 м²;

= 1.2 m ² ;

V _xpn = 0.6 m ³ - the volume of combustible decylin in the fuel tank of the product X-55.

In this way:

- for metallic material k ₁ = 18.2743;

- for a polymeric material k ₂ = 1.6868.

Sample volume fuel detsilin v _COI thermostating be one party of constructional materials with a test temperature is set to be 0.0015 m ³ (1.5 L), which amounts to 0.9 of the glass container for incubation.

Knowing the geometric coefficients of capacity k ₁ and k ₂ for a specific material of the fuel tank of the product X-55, calculate the total surface area s _2isp and _{s2isp of the} surface of the samples of structural materials of the fuel tank of the product X-55 for each batch at a specific temperature for temperature control according to the formulas:

In this way:

- for metal material

- for polymer material

Thermostating is carried out at temperatures of 373 K, 363 K, 353 K and 343 K. In the specific case, the temperature is T _max = 373 K, since at a higher temperature (above 383 K) the content of the antioxidant additive ionol in combustible deciline decreases sharply, which leads to a sharp deterioration in its quality.

Thermostatically sequentially all four batches of samples of combustible deciline with samples of structural materials of the calculated area starting from the highest temperature T _max = 373 K. In the process of temperature control, we periodically take ten samples of combustible decilin and determine the acidity values in accordance with GOST 11362-96. Thermostatting of the first batch is stopped at the time when the acidity of the sample of combustible decilin reaches the set value of 0.2 mg KOH / 100 cm ^{3 of} combustible decilin (Fig. 3, 72 h). The remaining three batches are thermostatically controlled during this time (72 hours) at given temperatures of 363 K, 353 K, 343 K (Fig. 3).

Based on the data obtained, we construct graphical dependences of a continuous increase in the acidity of samples of a decilin sample of each batch of fuel from the duration of temperature control at specific temperatures in one coordinate system.

Since the acidity values of samples of a sample of decilin fuel during the temperature control process are constantly increasing, for further calculation it is necessary and sufficient to use only two graphical dependencies (Fig. 3).

On the axis of the values of acidity we select a point (0.125 mg KOH / 100 cm ^{3 of} fuel), from which a straight line parallel to the axis of the values of the duration of temperature control crosses two graphical dependences (for T = 373 K and T = 363 K), for which we determine by the intersection points the duration of temperature control until the acidity value at the selected point is 0.125 mg KOH / 100 cm ^{3 of} combustible deciline for two temperatures of 373 K and 363 K, τ ₃₇₃ = 35 h, τ ₃₆₃ = 72 h (Fig. 3).

We calculate the value of the energy indicator In combustible deciline to be stored in the fuel tank of the product X-55, according to:

where B is the energy indicator, K;

T ₁ , T ₂ - temperature thermostating of fuel decilin 363 K and 373 K;

,

- продолжительность термостатирования до достижения кислотности значения 0,125 мг КОН/100 см³ горючего децилин при температурах 363 К и 373 К соответственно.

,

- the duration of temperature control until the acidity reaches 0.125 mg KOH / 100 cm ^{3 of} combustible deciline at temperatures of 363 K and 373 K, respectively.

Since 1000≤V≤45000, substituting the obtained value of energy indicator B in the formula for calculating the predicted shelf life of combustible decilin in the fuel tank of the product X-55

where τ _xp is the predicted shelf life of combustible decilin in the fuel tank of product X-55 in climatic region II ₁₀ (warm wet);

τ _max - the duration of temperature control at a temperature T _max , during which the value of the acidity of combustible decilin reached a predetermined value equal to 0.2 mg KOH / 100 cm ³ fuel;

τ _xpj is the duration of the jth temperature interval for one year for climatic region II ₁₀ (warm wet) storage (Table 2 - reference data on the climatic region of storage of combustible decilin (GOST 16350-80)), hour;

T _max is the temperature control temperature of the first batch of samples of structural materials with combustible decilin, K;

T _j - the average temperature of the j-th temperature range for the climatic region II ₁₀ (warm wet) storage, K (table 2);

N is the number of accepted temperature ranges in the climatic region II ₁₀ (warm wet) storage (table 2).

The calculated predicted shelf life τ _{xp of} combustible decilin in the X-55 product is 12 years. Considering the year of production (1988) and the duration of storage of combustible decilin in the product X-55, we get the total shelf life of combustible decilin in this product since 2009 at least 12 years, subject to the conditions and rules of storage of fuel, as well as annual quality control .

Analysis and generalization of the data on experimental storage in special warehouses (bases) and in tanks of missile weapons carried out at the FAU “25 State Research Institute of Chemotology of the Ministry of Defense of Russia” showed that the shelf life of combustible deciline without loss of quality is at least 30 years, which is good correlates with the calculated data (from 1988 to 2009 - 21 years, and the calculated predicted shelf life τ _xp = 12 years, total not less than 30 years).

For all other hydrocarbon fuels, the method is implemented in the same way, only taking into account changes in the set parameters of the intended storage medium and acidity values during thermostating process.

Example 2

It is necessary to forecast the shelf life of combustible synthine (GOST RV 50613-93), produced in 1992 and stored in the railway tank of the ZhDTS, in climatic region II ₅ (moderate) (GOST 16350-80) with an average annual air temperature of 277, 6 K.

Determine the numerical values of the coefficient of capacity k ₁ (table 1 - materials in contact with fuel during storage in natural conditions in storage facilities) for the material

- площадь контакта горючего синтин с конструкционным материалом ЖДЦ, м²;Where

- the contact area of the fuel synthine with the structural material ZhDC, m ² ;

;

;

V _xpn = 59 m ³ - the volume of combustible synthine in the ZhDC.

In this way:

k ₁ = 6.942.

The volume of a sample of synthin v _isp fuel to be thermostated with one batch of structural materials at the same test temperature is set to 0.002 m ³ (2 L), which is 0.9 from a glass container for temperature control.

Knowing the geometrical coefficients of capacity k ₁ for a particular ZhDC material, calculate the total area s _{1sp of a} sample of _ZhDC structural materials for each batch for temperature control according to the formula:

In this way:

s _1sp = 0.11 m ² .

Thermostating is carried out at temperatures of 353 K, 343 K, 333 K and 323 K.

In a particular case, the temperature T _max = 373 K, since at a higher temperature (above 363 K) transient oxidation processes begin in combustible synthine, which leads to a sharp deterioration in its quality.

Thermostatically sequentially all four batches of samples of combustible synthine with a sample of structural material of the calculated area starting from the highest temperature T _max = 353 K. In the process of thermostating, we periodically select at least ten samples of combustible synthine and determine the acidity values in accordance with GOST 11362-96. The temperature control of the first batch is stopped at the time when the acidity of the sample of combustible synthine reaches a predetermined value of 0.5 mg KOH / 100 cm ^{3 of} combustible synthine (Fig. 4, 22.4 h). The remaining three batches are thermostatically controlled during this time (22.4 hours) at temperatures of 343 K, 333 K, 323 K (Fig. 4).

Based on the data obtained, we construct graphical dependences of a continuous increase in the acidity of samples of a sample of fuel synthine of each batch on the duration of temperature control at specific temperatures in one coordinate system.

Since the acidity values of samples of a sample of a synthine fuel continuously increase during thermostating, for further calculation it is necessary and sufficient to use only two graphical dependencies (Fig. 4).

On the axis of acidity values, we select a point (0.198 mg KOH / 100 cm ^{3 of} fuel), from which a straight line parallel to the axis of the thermostating duration values intersects two graphical dependences (for T = 353 K and T = 343 K), for which we determine by the intersection points the duration of temperature control until the acidity is reached, at a selected point equal to 0.198 mg KOH / 100 cm ^{3 of} combustible synthine, for two temperatures 353 K and 343 K, τ ₃₅₃ = 22.4 h, τ ₃₄₃ = 10.01 h (Fig. 4) .

We calculate the value of the energy index B of combustible synthine to be stored in the ZhDC, according to dependence (1):

,

,

where B is the energy indicator, K;

T ₁ , T ₂ - temperature thermostat fuel synthine 343 K and 353 K;

,

- продолжительность термостатирования до достижения кислотности значения 0,198 мг КОН/100 см³ горючего синтин при температурах 343 К и 353 К соответственно.

,

- the duration of temperature control until the acidity reaches 0.198 mg KOH / 100 cm ^{3 of} fuel synthine at temperatures of 343 K and 353 K, respectively.

Since 1000≤V≤45000, substituting the obtained value of the energy indicator B in the formula for calculating the predicted shelf life of fuel synthine in the ZDC

,

,

where τ _xp is the predicted shelf life of the fuel synthine in the ZHDC in climatic region II ₅ (moderate);

T _max - the duration of temperature control at a temperature T _max , during which the value of the acidity of fuel synthine reached a predetermined value equal to 0.5 mg KOH / 100 cm ³ fuel;

τ _xpj is the duration of the jth temperature interval for one year for climatic region II ₅ (moderate) storage (Table 2 - reference data on the climatic region of storage of fuel synthine (GOST 16350-80)), hour;

T _max is the temperature control temperature of the first batch of a sample of structural material with combustible synthine, K;

T _j is the average temperature of the j-th temperature range for the climatic region II ₅ (moderate) storage, K (table 2);

N is the number of accepted temperature ranges in the climatic region II ₅ (moderate) storage (Table 2).

Calculated the projected shelf life τ _xp fuel syntin in ZHDTS is 1.8 years. Considering the year of production (1992) and the duration of storage of combustible synthine in the ZhDC, we obtain the total shelf life of combustible synthine in this storage medium from 2009 at least 1.8 years, subject to the conditions and rules of storage of fuel, as well as annual quality control .

Analysis and synthesis of data on the experimental storage of synthine in a special warehouse conducted at the FAU “25 State Research Institute of Chemotology of the Ministry of Defense of Russia” showed that after 18 years of storage the value of fuel acidity exceeds the specified value according to GOST RV 50613-93 and the synthine becomes substandard (since 1992 in 2009 - 17 years and the calculated predicted shelf life τ _xp = 1.8 years, total not less than 18.8 years).

Table 4 shows the results of evaluating the acidity values of the fuel synthine, which is in experimental storage in a special warehouse, and the experimental data obtained by the proposed method.

An analysis of the data and experimental storage of synthine (table 4, figure 5) shows that they correlate well with each other.

Thus, by using temperature data (τ _xpj , T _j , N) for a specific climatic region of the proposed fuel storage location, taking into account the influence of various structural materials of the storage medium (S _hrn ) and the estimated volume (V _xpn ) of fuel, the invention allows predicting fuel storage life with a high degree of accuracy.

Table 1 Materials in contact with fuel during storage under natural conditions in storage facilities Storage facility Fuel The amount of fuel in the storage medium, V _hrn , m ³ Materials Contact area with fuel, S _hrn , m ² Product X-55 Decilin 0.6 1. Metal 13 2. Polymer 1,2 ZDC Sintin 59 1. Metal 105,2 2. Polymer -

Claims (1)

A method for predicting the shelf life of hydrocarbon fuels in storage media, including sampling hydrocarbon fuels, determining the information indicator of each sample, comparing the results with a given value according to current GOST or technical specifications for this fuel, if not exceeded, thermostating is carried out at a given temperature with prepared samples structural materials in containers of a given volume, with which fuel is in contact with COROLLARY storage and subsequent measurement period of storage of hydrocarbon fuels at the mathematical relationship, characterized in that as an information index characteristic acidity analyte hydrocarbon fuel further define the volume V _hrn be stored hydrocarbon fuel and contacting this volume area S _xpn surface of each structural material intended storage facility, which is calculated capacity factors k _i for each constructional mother lu by the following relationship

,
Where

- the area of contact of the fuel with the structural material of the storage medium, m ² ;
V _hrn - the amount of fuel in the storage medium, m ³ ,
set the volume of the fuel sample v _isp to be thermostated with one batch of structural materials at one test temperature equal to 0.002 m ³ , calculate the total area

the surface of the samples of each structural material for temperature control according to the following relationship

,
4 batches of samples of structural materials are prepared, the total area of which is equal to the calculated total surface area of each structural material, the first batch of samples of structural materials is thermostated with a sample of the analyzed fuel at a temperature T _max = 353 K, periodically taking at least 10 fuel samples and determining the current acidity values of each sample, when the acidity reaches the set value equal to 0.5 mg KOH / 100 cm ^{3 of} fuel, thermostatting is stopped, the maximum the duration of temperature control _max until the acid reaches the set value equal to 0.5 mg KOH / 100 cm ³ fuel, and build a graphical dependence of the continuous increase in the acidity of the fuel on the duration of temperature control at a temperature of 353 K, thermostatment of other batches is carried out at temperatures of 343 K, 333 K , 323 K, during the fixed duration of temperature control of the first batch, at least 10 fuel samples from each batch are periodically taken and the current acidity values of each s, building a graph of the continuous increase in the fuel sample acidity values of samples of each batch in the same coordinate system as that for the first party, selected two graphics function, thus on axis acidity values selected point 0.198 mg KOH / ^cm3 fuel from which direct parallel to the axis of the values of the duration of temperature control, intersects these two graphical dependencies for T ₁ = 353 K and T ₂ = 343 K, for which the duration of temperature control is determined by the intersection points until the acid value is reached the analyzed hydrocarbon fuel at a selected point equal to 0.198 mg KOH / cm ³ fuel for two batches of fuel at temperatures T ₁ = 353 K and T ₂ = 343 K, after which the value of the energy index B of the analyzed fuel is calculated according to the following dependence

where B is the energy indicator, K;
T ₁ , T ₂ - temperature T ₁ = 353 K and T ₂ = 343 K temperature control of fuel with samples of structural materials;

- the duration of temperature control of the fuel until the acidity reaches 0.198 mg KOH / cm ³ fuel at temperatures T ₁ , T ₂ , respectively, h,
and with values of 1000 В B 45 45000, the shelf life of the fuel in a specific storage medium and a specific climatic region is predicted according to the following formula

where τ _xp is the predicted shelf life of the fuel, years;
τ _max - the duration of thermostatting of the fuel at a temperature T _max , during which the acidity reaches a predetermined value equal to 0.5 mg KOH / 100 cm ³ fuel;
τ _xpj is the duration of the jth temperature interval for one year for a specific climatic region of operation of the storage medium, h;
T _max - temperature thermostating of the fuel sample with the first batch of structural materials, K;
T _j is the average temperature value of the j-th temperature range for a specific climatic region of operation of the storage medium, K;
N is the number of accepted temperature intervals in a particular climatic region of operation of the storage medium.

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