# Method for defining at least one power property of gas fuel mixture by measuring physical properties of a gas mixture

FIELD: power engineering.

SUBSTANCE: method involves 1) measuring n physical properties φ_{i} of given gas mixture at temperature T and/or single physical property φ_{i} at n different temperature values; 2) determining gas composition comprising n+1 ingredients on basis of mentioned physical properties, that is to be equivalent to the given gas mixture; 3) deducing power properties of the given mixture from given known composition of the equivalent gas.

EFFECT: simplified method; higher information capacity of property definition.

12 cl, 3 dwg, 1 tbl

The object of the present invention is a method for determining at least one energy characteristics of the combustible gas mixture by measuring the physical characteristics of this gas mixture, the composition of the gas that is equivalent to this gas mixture and removing energetic properties based on the specified structure.

PRIOR art

Energy characteristics, such as the calorific value of the gas Wobbe index, combustion, and methane number, are of great interest from the point of view of industry. Indeed, changes in gas composition (e.g., natural gas), in connection with the plurality of supply sources (Algerian, Norwegian, Russian gas and the like), can be a cause of serious damage to stationary engines running on gas. These motors are commonly used for the simultaneous production of heat and electricity (cogeneration). In addition, the effective use of combustible gases in internal combustion engines mainly depends on the properties of their ignition and properties of burning.

Energy characteristic that allows you to track changes in the quality of natural gas in connection with its anti-knock ability, is the methane number.

<> Flammable gases having different value associated with their very different energy characteristics also have different origins: gas, obtained by dry distillation of wood; gas obtained by gasification of coal, natural gases, and so onIn those cases, when in power internal combustion engines used biogas, changing the composition of the gas can seriously affect the performance of this engine. For example, there may be power fluctuations associated with changes in the rate of net calorific value (this figure may change in the interval from 10 to 25 MJ/m^{3}). Thus, the dimension of the lower calorific value of biogas is extremely important for optimal functioning of the engine.

Wobbe index (Wobbe) is another important energy characteristic of the gas fuel (it can change in the range from 10 to 30 MJ/m^{3}). This indicator is an important criterion of interchangeability of various gases in power plants. Changing the gas composition does not cause any significant changes of the coefficient of excess air and the rate of combustion, when the Wobbe index remains approximately constant. This indicator can be calculated based on caloric ability and using the following relationship:

in which PCI is a lower calorific value of gas, and d is the density of the gas.

There are many ways to measure the quality of the gas fuel, among which we can point out ways to measure the calorific value and the method of measuring methane number.

a) a Means of measuring the calorific value

Knowing the composition of the gas mixture, it is easy to calculate its calorific value, using individual values for each of the components of this gas.

Direct determination of calorific value can be carried out using manual calorimeters or automatic calorimeter, such as the calorimetric bomb, gas calorimeter of Cancers and magnetic type "Union".

These traditional methods are cumbersome, time consuming and represent a significant difficulty in applying in cases when you want to know the calorific value of the gas mixture in the process of installation.

The method proposed for the calculation of the calorific value, which is described in published international application WO 99/36767, takes into account the measurement of two physical properties (velocity of propagation of sound in this gas environment and its conductivity). This method was developed PR is the use of natural gas, presents all varieties of gas circulating in the distribution system in the UK. Laboratory studies performed with the use of these natural gases, allowed to determine the speed of propagation of sound in these gases with subsequent determination of the relationship of the results of measurements with calorific value. Because measurements are only one of the specified characteristics were not sufficient to track changes in the calorific value in the presence or absence of natural gases of any significant amount of inert impurities, it has been proposed to measure a different physical characteristics (thermal conductivity) in combination with the measurement of the speed of sound. In accordance with this method, the calorific value is calculated as follows:

where

- CV is the calorific value;

- ThC_{H}is the conductivity at temperature T_{h};

- ThC_{L}is the conductivity at temperature T_{L};

SoS represents the propagation velocity of sound at the temperature of the environment;

- T_{and}represents the ambient temperature for gas;

- a, b, C, d, e and f are constants (constant is AMI).

Constants were determined by processing data obtained for gas samples of different origin used in the UK, using the regression method. Thus, we consider a method of determining the calorific value is based on measurements obtained only for natural gas, with distribution in the UK and therefore cannot be widely generalized.

Another way to determine the calorific value is based on determining the percentage of nitrogen and carbon dioxide in this gas, and the density value of the gas. The formula below was used by Khandwalla (Candwell) (1967); it is only valid for gases, the Wobbe index which is enclosed in the interval from 43,4 to 44.4 MJ/m^{3}(Groningen gas):

In this formula, K_{CO2}represents the proportion of carbon dioxide, a K_{N2}represents the fraction of nitrogen in this gas.

Both of the above method is not applicable, however, in relation to the totality of gases occurring in Europe.

b) Methods of measuring methane number

Experimental determination of methane number

Measuring methane number is usually carried out using standard research device type CFR/RDH (Engl.: Cooperative Fuel Research / Remoable Dome Head) in accordance with the technical specifications, defined in the publication: Christoph et al. "Evaluation du pouvoir antidétonant des carburants gazeux au moyen de I indice de méthane et de leur application pratique dans les moteurs á gaz" (Kristof and other Assessment antiknock ability of gaseous fuels using methane indicator and their practical use in gas engines) - MTZ, 33, April 1972, No. 10.

Chemical determination of the methane number (through analysis of the chemical composition)

Another way to determine methane was developed by Ryan and'callaghan [RYAN et al. Journal of Engineering for gas turbines and Power, October 1993, t/769 and CALLAHAN et al. 18^{th}. Annual Fall Technical Conference of the ASME Internal Combustion Engine Division, 1996, ICE - v.27-4.], further improved Waukesha (Waukesha) [Selberg, CIMAC Congress 1998]. These authors introduced a new metric, similar to the methane number, called the index WKI (U.S. patent No. 6061637).

Graphical determination of the methane number

The method allows the calculation of the methane number for a given fuel gas based on the chemical composition of the latter, was developed by Christophe and others [see above link]. This method consists in combining the various components in groups of two or three, for which methane number submitted on the appropriate charts. The corresponding equation has the following form:

where

IMj: methane number for a mixture of j consisting of two or the PEX gases;

y_{j}: volumetric concentration of a mixture of j in the total mixture, and

IM methane is a measure of the overall mixture.

The above equation may be used only if

charts for each of the groups allocated in this mixture.

In addition, it must be observed a number of specific requirements:

- deviations between IM_{j}should not vary by more than five units;

- each group must consist of at least three components;

group can be composed of one gas only on the condition that it satisfies the first rule;

- easy detonating components (such as butane) must always be included in the three-group together with components having high anti-knock ability (e.g., methane);

- integral part containing five or more carbon atoms, can be combined with butane, because they are contained in gases only in trace amounts.

For gas mixtures containing nitrogen, or carbon dioxide in quantities not exceeding 9 and 2%, respectively, methane number is determined without taking into account these parts. In this case, the calculation error does not exceed two units methane number.

If the content of the above components p is Evesham present value, then the methane number is calculated in accordance with the following equation:

in which

IM(not) shall be calculated in accordance with equation (4);

IM(not flammable.) is calculated using a three-component diagram

CH_{4}-CO_{2}-N_{2}in which all saturated hydrocarbons conditionally accept

identical to methane.

Empirical determination of the methane number.

1) the Ratio of IM=f(PCl ×CO_{2}, the density or volume weight).

A simple equation based on the measurement of NCV (PCI), the density of the gas and the content of carbon dioxide was developed in the German company Ruhrgas (Ruhrgas). This equation, which is based on the reference model (AVL program, which performs the calculation of the methane number based on ternary diagrams), is a multiple linear regression, the form of which is as follows:

While PCl is a lower heat of combustion of the gas;

ρ is the density of the gas;

x_{CO2}represents the proportion of carbon dioxide in this gas. In addition, we developed two methods for calculating methane number based on the calorific value or the dielectric constant of this gas is,
its density and the content of carbon dioxide;

The first of these methods allows to determine the gas composition depending on the lower calorific value, density, and fraction of carbon dioxide (the algorithm of calculation), allowing to calculate methane number using AVL based on experimental data obtained using the CFR engine (see: Leiker M, et al. Evaluation of the Antiknocking Property of Gasseous Fuels by means of the Methane Number and its Practical Application to Gas Engines / Evaluation of anti-knock ability of gaseous fuels through methane number and its practical application to gas engines. ASME Paper 72-DGP-4, April 1972), as well as calculating the Wobbe index and calorific value of combustion. The method includes the assumption related to the nitrogen content in the gas. The final composition of the gas is determined using an algorithm based on an iterative calculation that combines a series of relations of second order to the lowest heat of combustion (patent EP 0939317 A2).

The second method, similar to the previous, allows to determine the gas composition depending on the magnitude of the dielectric constant, density of the gas and the fraction of carbon dioxide. The method involves two assumptions nitrogen content and lower heat of combustion of hydrocarbons. The final composition of this gas is determined using the algorithm based what about on an iterative calculation combining a series of relations of second order to the lowest heat of combustion (patent EP 1081494 A1).

2) the Optical absorption in the infrared spectrum.

Two ways to track changes in methane number, which include measurement of optical absorption in the infrared spectrum, described in the publications of international applications WO 98/25128 and WO 00/50874.

Both empirical method of determining methane number can achieve accuracy on the order of +/- 2 units of methane number.

In addition, when using variables (such as net calorific value), the measurement of which can be physically and economically difficult, the above methods can be used only by those users who can effectively measure the lowest heat of combustion of gaseous fuels, their density and the concentration of carbon dioxide (for example, such users, as the German company Ruhrgas, which effectively carries out measurements of these quantities at their gas stations).

All methods used to calculate the methane number and NCV represent a ratio based on one, two or three physical characteristics. The establishment of any regression requires consistent calibration, because the approach of the two who is empirical.

The above methods are of considerable inconvenience, the first of which is the need to establish the exact relationship between the energy characteristics that are detected, and those physical properties that are for this purpose used. In addition, the difficulty of determining the positive or negative effects of some compounds, which influence on methane number, for example, or on the lowest heat of combustion cannot be neglected, is also a disadvantage inherent in such methods.

Finally, it is extremely rare these ratios can calculate several energy characteristics at the same time.

The present invention has as its objective to eliminate these inconveniences and offers a new easy-to-use method that is designed to determine at least one energy characteristics of gas (natural gas, biogas, etc.), which has numerous advantages, in particular, the possibility of simultaneous determination of methane number and calorific value gases, which are two characteristics that are fundamentally important for the normal functioning of the gas engines designed for cogeneration (simultaneous production of electricity and those of the La).

The INVENTION

The method corresponding to the present invention, designed to determine at least one energy characteristics of the gas mixture is as follows:

1) measurement for the specified gas mixture n physical characteristics φ_{i}when the temperature T and/or one of the physical characteristics φ_{i}at n different temperatures;

2) determination based on these physical characteristics, the composition of the gas of n+1 component equivalent to the above-mentioned mixture;

3) deducing from the specified composition of gas equivalent energy performance of a specified gas mixture.

The gaseous mixture to be tested, may be a gaseous fuel such as natural gas or gas of biological origin, such as biogas or gas produced through gasification. This mixture may consist of methane and contain non-combustible gases such as carbon dioxide or nitrogen. In addition to methane, the gas mixture may also contain at least one other saturated hydrocarbon comprising from 2 to 5 carbon atoms, such as ethane, propane, butane or pentane. Equivalent gas may include hydrogen and/or carbon monoxide.

Specified equivalent gas may contain n+1 components, while n is an integer, greater than or equal to 1, preferably equal to 2 or 3.

Physical characteristics provided to the dimension may represent the speed of sound, thermal conductivity, dynamic viscosity, density, coefficient of optical refraction, dielectric constant of the gas, the optical absorption in the infrared region of the spectrum, or any other physical characteristic of the gas at temperature T.

Preferably, the method provides for the use of the following pairs of physical characteristics φ_{1}and φ_{2}:

is the dynamic viscosity and thermal conductivity;

- thermal conductivity at temperatures T_{1}and T_{2};

- coefficient of optical refraction and thermal conductivity;

- the speed of sound transmission coefficient of optical refraction.

Set the energy characteristics may represent a methane number, calorific value, Wobbe index and combustion.

Before implementation of phase 1 according to the method in accordance with the present invention previously performed calibration, consisting either in several series of measurements of the physical characteristics φ_{i}equivalent gas comprising n+1 part, and the composition of which is known, or when used in the Institute of numerical method,
for example, such as a method that matches the descriptions in ASTM D 25-98-68, and then determined the relationship between physical characteristics and content of each of the components of the specified gas equivalent.

The term "equivalent" refers only gas that includes n+1 integral part with the same n physical characteristics, and that this "real" gas (in other words, the same value of propagation velocity of sound, or, for example, the same conductivity)for which you want to determine the energy characteristics.

For example, in the preferred embodiment of the present invention can be measured two (or three) physical characteristics of the gas mixture based on these physical characteristics of the composition of the three (or four) gas equivalent.

In this case, it may be composed of three (or four) chart based on any triplet combination of elementary gases such as CH_{4}-C_{2}H_{6}-C_{4}H_{10}or CH_{4}-C_{2}H_{6}-C_{4}H_{10}-N_{2}based on the measurements of all possible combinations of the physical characteristics of the two (ternary diagram) or three by three (chetirikanalen the nye chart).

The specified three-component chart preferably based on the equivalent three-component structure of the kind of CH_{4}-C_{2}H_{6}-N_{2}CH_{4}-C_{2}H_{6}-C_{4}H_{10}CH_{4}-C_{2}H_{6}- C_{4}H_{10}or CH_{4}-C_{2}H_{6}- C_{4}H_{10}- N_{2}.

In General, real gases, such as natural gas, can include up to 5-6 components, sometimes even more.

Ternary diagram (or four) is a diagram of the gas mixture, which comprises only three different compounds (or, respectively, four connections). Thus, natural gases can be represented in diagrams such as pseudoconcave, or "equivalent" gas.

The inventors have found that a real gas has the same power characteristics as the equivalent gas, recreated based on the two physical characteristics of the real gas.

Figure 1 presents a three-part chart X_{1}-X_{2}-X_{3}, which can be represented by the measurement results of two different physical characteristics real gas mixture.

X_{1,}X_{2}or X_{3}can be mapped to any compound included in the composition of the gas, such as IU the Anu,
the ethane or nitrogen (X_{1}+X_{2}+X_{3}=1, or 100%).

Physical characteristics indicated on this chart, via φ_{1}and φ_{2}match each one of the dimensions of the above physical characteristics. This means that the curve, which presents the value of the φ_{1}that corresponds, for example, the velocity of propagation of sound, equal to 300 m/s is an infinite number of different three-component compositions (specific mixture of three gases, or three-part composition, is always represented in the diagram by a single point).

In fact, there are many different gas mixtures, which have the same value for the speed of sound or the same value of thermal conductivity. Taking into account that each mixture, consisting of three compounds, represented by a single point on an equilateral triangle (three-component diagram), the result is an infinite set of points representing the same value of the physical characteristics (speed of sound, viscosity, thermal conductivity etc)

The intersection of two contour lines, each of which corresponds to the constant value of the physical characteristics (i.e. constant values φ_{1}and φ_{2}characterizes only Techcom onentry composition of an infinite number of compositions,
describe each of the two curves corresponding to values φ_{1}and φ_{2}.

The intersection of two straight lines, which correspond to two measured physical properties, is only part of a three-component mixture.

In the more General case to vary the physical characteristics φ_{1}and φ_{2}thus, to cover the totality of the gases to be examined (for example, the set of natural gases), then this forms a network of direct, almost parallel to each other, corresponding to different values of physical characteristics φ_{1}.

The intersection between the two networks of lines, each of which corresponds to the different values φ_{1}and φ_{2}that is an infinite set of points that fully describe the ternary diagram.

It was found that it is possible to relate the coefficients a_{1}and b_{1}these networks direct physical properties φ_{1}, φ_{2}and the temperature.

Then these direct mutate so that they are applicable to the triangular region (these coefficients are expressed as a function of X_{1}X_{2}and X_{3}).

Finally, with the aim to characterize the totality described three-component diagram, the contents of each of the first connection,
part three-component gas, presented as a function of the physical characteristics (X_{1}, X_{2}and X_{3}presented as a function of the coefficients, which, in turn, depend on the physical characteristics and temperature).

X_{1}=f_{1}(X_{10},φ_{1},φ_{2}T)

X_{2}=f_{2}(X_{20},φ_{1},φ_{2}T)

X_{3}=1-X_{1}-X_{2}

φ_{1}and φ_{2}indicate here are two physical characteristics used to identify any gas triplet based on the above equations : X_{1}X_{2}and X_{3}indicate the content of each of the three components of the three-component gas; X_{10}corresponds to the lower limit of the coordinate axes X_{1}(0,4 figure 1 left), a X_{20}corresponds to the lower limit of the values represented on the coordinate axis X_{2}(0,2 figure 1 left).

The ratio describing the triplet X_{1}X_{2}and X_{3}characterize the entire ternary diagram as a whole. They vary with the type of the considered gas (natural gas, biogas or gas resulting from gasification), there is a special chart describing the biogas, as well as there is another special chart characterizing natural gas, whereas, the X_{
1}X_{2}, X_{3}and boundaries varies for different varieties of the considered gas.

On the basis of the thus determined, the three-component diagrams the person skilled in the art can easily determine the ratio, which is obtained X_{1}X_{2}and X_{3}when using conventional modeling tools.

Figure 2 presents an example of a three-component diagram X_{1}-X_{2}-X_{3}, which can be represented by the measurement results of two different physical characteristics. Moreover, in this chart lists the contents of the fourth component of X_{4}(X_{1}≡CH_{4}X_{2}≡C_{2}H_{6}, X_{3}≡C_{3}N_{8}and X_{4}≡N_{2}).

This component is not specified on the chart, despite the fact that he is real. Instead, the sum of the proportions of the compounds that are represented on the chart, not equal to 1, and 1-X_{4}.

This new chart is equivalent to four connections.

In order to characterize the ternary diagram in General, each of the three compounds in the final form presented as a function of the physical characteristics and from the fourth component of X_{4}(X_{1}X_{2}and X_{3}expressed as a function of the coefficients, which, in St. the first phase,
depend on the physical characteristics and temperature).

X_{1}=f_{1}(X_{10},φ_{1},φ_{2}X_{4}T)

X_{2}=f_{2}(X_{20},φ_{1},φ_{2}X_{4}T)

X_{3}=1-X_{1}-X_{2}-X_{4}

φ_{1}and φ_{2}indicate here are two physical characteristics used to identify any gas triplet based on the above equations : X_{1}, X_{2}and X_{3}indicate the content of each of the three components of the three-component gas; X_{10}corresponds to the lower limit of the coordinate axes X_{1}and X_{20}corresponds to the lower limit of the values represented on the coordinate axis X_{2}.

The fact of adding a dependent variable, X_{4}requires the measurement of the third physical characteristics that are sensitive to changes in X_{4}. This physical characteristic should be easy to measure.

The relations determining quadruplet X_{1}, X_{2}, X_{3}and X_{4}characterize the set of values that meet a four-part diagram. These ratios vary with the type of the considered gas (natural gas, biogas or gas resulting from gasification). They also may be easily determined by the person skilled in the art using conventional simulation tools is.

The Quad chart allows to increase the accuracy of calculation of such complex energy performance, as methane number.

This model resembles the previous, but it includes an additional dependent variable. In fact, if we take the example of natural gas, it is possible to obtain a three-component diagram CH_{4}-C_{2}H_{6}-C_{3}H_{8}in which the coefficients and_{i}and b_{i}indexed share of nitrogen in this gas.

Each of the coefficients depends on the physical characteristics and indexed fraction of nitrogen in the gas.

It is obvious that the use of this model is the ability to determine the percentage of nitrogen or determine the percentage of incombustible impurities in this gas (nitrogen + carbon dioxide) from the third physical characteristics. This feature should be sensitive to changes in nitrogen content, or of non-combustible impurities in General, this characteristic is, for example, the dynamic viscosity coefficient of the optical refractive index and optical absorption in the infrared region.

Following the above, it was found that the equivalent of a three-part composition can be derived using the following equations:

X_{3
=1-X1-X2}

in which

- φ_{1}and φ_{2}refers to two physical characteristics;

- X_{1}X_{2}and X_{3}indicate the content of each of the components of the three-component gas;

- X_{10}denotes the lower boundary coordinate axes X_{1};

- X_{20}denotes the lower boundary coordinate axes X_{2};

- a_{1}b_{1}, a_{2}and b_{2}are coefficients that depend on physical characteristics;

(ϕ_{1}; ϕ_{2})=(φ_{1}(T); φ_{2}(T)) for two different physical characteristics or

(ϕ_{1}; ϕ_{2})=(φ_{1}(T_{1}); φ_{1}(T_{2})) for two values of the temperature.

In addition, it was found that the equivalent of a four-part composition can be determined using the following equations:

X_{4}=f(ϕ_{3})

X_{3}=1-X_{1}-X_{2}-X_{4}

in which

- φ_{1}, φ_{2}and φ_{3}denote three physical characteristics;

- X_{1}X_{2}, X_{3}and X_{4}indicate the content of the four parts of the four-gas mixture;

- X_{10}denotes the lower boundary coordinate axes X_{1};

- X_{20}denotes the bottom face is the coordinate axis X_{
2};

- a_{1}b_{1}and_{2}and b_{2}are coefficients that depend on physical characteristics;

(ϕ_{1}; ϕ_{2})=(φ_{1}(T); φ_{2}(T)) for two different physical characteristics

or (ϕ_{1}; ϕ_{2})=(φ_{1}(T_{1}); φ_{1}(T_{2})) for two values of the temperature.

For example, the measurement of two physical characteristics ϕ_{1}and ϕ_{2}the gas mixture allows to determine the composition of three-component gas equivalent (n+1=3) by solving the following system of equations (I):

(1) and (2) are equations of lines isobarically three-component diagram X_{1}-X_{2}-X_{3}:

The composition of the equivalent gas can be determined using the graphical method. This method is based on the identification data at the point of intersection of the two lines isobarically ϕ_{1}and ϕ_{2}on the graph.

The composition of the equivalent gas can be determined using the following equations:

X_{3}=1-X_{1}-X_{2}

If the measured 3 characteristics equivalent gas has 4 components. Isobarically, corresponding to the three physical characteristics, represented by planes on chetyrekhkomponentnoi the th chart. The system of equations is the following:

In General measure n physical characteristics ϕ_{i}. The composition of gas equivalent is determined by solving a system of n+1 equations, with each equation expresses one isobarically on the diagram with n+1 regions.

The system of equations is the following:

This system of equations can also be written in the matrix form:

(IV) GC= Ω, where

If the physical characteristics are not linear, for solving the equation (IV) use the numerical method such as Newton-Raphson.

To a person skilled in the art will understand, what type of equation you want to use depending on the values of the number n.

The calculation of some of the energy characteristics of natural gas is the obvious consequence of a three-component or four-component diagrams. These are the lowest heat of combustion gas, the combustion or Wobbe index, it is extremely important for the gas workers. These characteristics are directly dependent on the composition of the gas. Methane number also depends on the composition, but indirectly. However, for its calculation, you can use the calculation program type AVL.

Thus, it appears possible to use the IC sensor, allows you to track changes of the lower heat of combustion, combustion and the Wobbe index for natural gas or any other gas (biogas, gas obtained from gasification), based on simple measurements of two different physical characteristics. It is also possible definition methane number in these gases.

In the case of natural gas and biogas measurement of thermal conductivity at two temperature levels, it is possible with good accuracy to determine the changes of the lower heat of combustion of these gases on the above three-component or four-component diagram.

In addition, a three-component or four-component composition corresponding to the described method, can be obtained by measuring the ratio of optical refraction in combination with the measurement of thermal conductivity or the speed of sound. Based on this structure it is possible to detect such energy characteristics, as methane number, the lower the calorific value or Wobbe index.

Measurement of gas viscosity in combination with any other physical characteristic is highly adequate in this methodology.

Thus, the object of the present invention is also a device for implementing the method in accordance with the present invention, when the specified device is about includes:

at least n sensors designed for measuring physical characteristics φ_{i};

is an electronic module designed to determine the composition is equivalent to a three-component or four-component gas and the desired power characteristics.

The physical characteristics depends on the type of three-component diagrams and how strong or weak these characteristics are interdependent.

The method in accordance with the present invention is applicable to all natural gases of various origins. This is demonstrated by the results shown in Figure 3, which represent the energy characteristics (NCV of PCI, Wobbe index and the combustion PCO), real and received in accordance with the method according to the present invention, for natural gas with the following composition:

Table The composition of the natural gas | |||||||

France | Algeria | North America (4) | Norway | Russia(6) | Holland | ||

Lac(1) | Skikda (2) | Arzew (3) | The place (5) | Groningen (7 | |||

CH_{4} | 97,3 | 91,2 | 88,6 | than 94.69 | 88,2 | 96,2 | to 83.5 |

With_{2}H_{6} | 2,1 | 6,5 | 8,2 | 2,58 | of 5.4 | 1,2 | 3,6 |

With_{3}H_{8} | 0,2 | 1,1 | 2 | 0,2 | 1,2 | 0,3 | 0,7 |

With_{4}H_{10} | 0,1 | 0,2 | 0,6 | 0,06 | 0,4 | 0,1 | 0,2 |

C_{5}H_{12} | 0 | 0 | 0 | 0,03 | 0,2 | 0,1 | 0,1 |

N_{2} | 0,3 | 1 | 0,6 | 1,63 | 3,2 | 1,8 | 10,8 |

CO_{2} | 0 | 0 | 0 | 0,81 | 1,4 | 0,3 | 1,1 |

Used in these studies three-component gas was a gas composition of form CH_{4}-C_{2}H_{6}-C_{3}H_{8}and CH_{4}-C_{2}H_{6}-N_{2}and physical characteristics φ_{1}and φ_{2}represented respectively:

- heat rovagnati and the ratio of optical refraction for the three-component gas CH_{
4}- C_{2}H_{6}-C_{3}H_{8};

- thermal conductivity and the coefficient of optical refraction or the speed of sound transmission coefficient of optical refraction for the three-component gas CH_{4}-C_{2}H_{6}- N_{2}.

The method corresponding to the present invention, allows to determine the physical characteristics of the gas mixture with an average deviation of about 1%.

1. Method for determining at least one energy characteristics of the combustible gas mixture, characterized in that it includes

1) measurement for the specified gas mixture n physical characteristics φ_{i}when the temperature T and/or one of the physical characteristics φ_{i}at n different temperatures,

2) determining on the basis of these physical characteristics of the composition of the gas, is equivalent to the above-mentioned mixture comprising n+1 component

3) deducing the energy characteristics of the specified gas mixture from the specified well-known composition of gas equivalent.

2. The method according to claim 1, characterized in that the physical characteristics φ_{i}perform the following characteristics: the speed of sound, thermal conductivity, dynamic viscosity, density, coefficient of optical refraction, dielectric constant, optical absorbance which begins in the infrared region.

3. The method according to claim 1 or 2, characterized in that the components included in the gas equivalent, choose among the following substances: methane, saturated hydrocarbons containing from 2 to 5 atoms of carbon, nitrogen, non-combustible gases, hydrogen or carbon monoxide.

4. The method according to claim 1 or 2, characterized in that the equivalent gas is a three-component gas consisting of methane and two saturated hydrocarbons containing from 2 to 5 carbon atoms, or from methane, one of a saturated hydrocarbon containing from 2 to 5 carbon atoms, and nitrogen or non-combustible gases.

5. The method according to claim 1 or 2, characterized in that the equivalent gas is a four-component gas consisting of methane, two saturated hydrocarbons containing from 2 to 5 carbon atoms, and nitrogen or non-combustible gases.

6. The method according to claim 1 or 2, characterized in that the physical characteristics ϕ_{1}and ϕ_{2}carry out respectively from among the following characteristics: dynamic viscosity and thermal conductivity, thermal conductivity at two values of temperature T_{1}and T_{2}the optical refraction coefficient and thermal conductivity, speed of sound transmission coefficient of optical refraction.

7. The method according to claim 1 or 2, characterized in that prior to step (1) produce calibration, comprising the I or series of measurements of the physical characteristics φ
_{i}equivalent gas, the composition of which is known, and the number of compounds included in its composition, is equal to n+1, or in the application of the numerical method, and determine the ratio between these physical characteristics such equivalent gas and the content of each of the component parts.

8. The method according to claim 1 or 2, characterized in that the composition is equivalent to a three-component gas mixture is determined by a three-component diagram using the following equations:

X_{3}=1-X_{1}-X_{2},

in which ϕ_{1}and ϕ_{2}refers to two physical characteristics;

X_{1}, X_{2}and X_{3}indicate the content of each of the components of the three-component gas;

X_{10}denotes the lower boundary coordinate axes X_{1};

X_{20}denotes the lower boundary coordinate axes X_{2};

a_{1}b_{1}and_{2}and b_{2}are coefficients that depend on physical characteristics;

(ϕ_{1}; ϕ_{2})=(φ_{1}(T); φ_{2}(T)) for two different physical characteristics, or

(ϕ_{1}; ϕ_{2})=(φ_{1}(T_{1}); φ_{1}(T_{2})) for two values of the temperature.

9. The method according to claim 1 or 2, characterized in that the composition is equivalent to a four-gas mixture is determined using the following equations:

X_{4}=f(ϕ_{3});

X_{3}=1-X_{1}-X_{2}-X_{4},

in which ϕ_{1}that ϕ_{2}and ϕ_{3}denote three physical characteristics;

X_{1}, X_{2}, X_{3}and X_{4}indicate the content of the four parts of the four-gas mixture;

X_{10}denotes the lower boundary coordinate axes X_{1};

X_{20}denotes the lower boundary coordinate axes X_{2};

a_{1}b_{1}, a_{2}and b_{2}are coefficients that depend on physical characteristics;

(ϕ_{1}; ϕ_{2})=(φ_{1}(T); φ_{2}(T)) for two different physical characteristics, or

(ϕ_{1}; ϕ_{2})=(φ_{1}(T_{1}); φ_{1}(T_{2})) for two values of the temperature.

10. The method according to claim 1 or 2, characterized in that carry out the determination of methane number, the Wobbe index, calorific value, combustion or combustion.

11. The method according to claim 1 or 2, characterized in that the gas mixture is chosen among natural gas, biogas is whether gases, produced by gasification.

12. The method according to claim 1 or 2, characterized in that the gas mixture is a natural gas or biogas.

**Same patents:**

FIELD: technology for diagnosing status of motor oil, possible use for determining quality of motor oil during operation and its fitness for further use.

SUBSTANCE: in accordance to method for determining content of liquid in motor oil, motor oil is heated up and by intensiveness of characteristic air bubbles, presence of liquid is evaluated, while firstly a template made of wire in form of mesh is applied to crucible of Cleveland machine, heated up with heating speed 6°C per 1 min up to 100°C, in range of temperatures 120-140°C heating is decreased down to 2°C per 1 minute, then position of cells in contour, formed by air bubbles in template, is visually memorized, further, contour is transferred over a squared paper, by squares, value of area of contour surface is calculated by its value, percentage of liquid is determined using standard depending on base for motor oil.

EFFECT: increased precision of detection of presence of cooling liquid in oils and its percentage.

3 tbl, 2 dwg

FIELD: measurement engineering.

SUBSTANCE: method and device can be used in systems for survey, transportation and preparation of oil. Continuous and simultaneous measurement of volumetric discharge Q1 and Q2 is performed in two points standing apart along flow travel in pipeline; the measurements are carried out by means of two flowmeters. Behind the first point Q1, the local hydrodynamic disturbance is generated in flow by means of expansion of cross-section of flow. Second measurement is carried out at expanded part of flow. Availability of gas is judged from excess in setting relatively current values Q1 and Q2, which value is specified in controller to which controller the both flowmeters are connected. Device for realization of the method is made in form of insertion n the pipeline.

EFFECT: improved reliability of measurement.

2 cl, 1 dwg

FIELD: lubricants.

SUBSTANCE: invention relates to the field of testing petroleum derivatives, in particular to testing hygroscopicity of aviation synthetic oils, and can be utilized in institutions engaged in development and application of lubricating oils for aircraft techniques and for estimating changes in quality conditions of aviation synthetic oils from tendency of oils to water absorption under operation conditions. In a method of estimating hygroscopicity of oils from amount of absorbed water, including sampling oil, keeping sample at specified relative humidity and temperature in presence of distilled water, and then calculating amount of absorbed water using thus obtained dependence, additionally calculating content of water in initial sample (C_{0}), specifying keeping time (t) for sample of oil at specified relative humidity and temperature, and calculating amount of absorbed water (C_{1}) in oil sample from mathematic dependence taking into consideration experimentally found maximum water solubility constant (C_{max}) and constant coefficient (k_{a}) for particular kinds of aviation synthetic oils.

EFFECT: reduced determination time and labor expenditure for determination, increased sensitivity of method under oil operation conditions without losses in accuracy and reproducibility.

1 dwg, 3 tbl

FIELD: analytical methods.

SUBSTANCE: invention is intended for use as a means of metrologically supporting measurement techniques in determination of total alkaline number of motor oils and lubricating materials. This means is represented by composition containing 75-84% liquid hydrocarbons, 0.05-6% water-soluble alkali component, and 15-20% aliphatic alcohol. Use of standard specimen allows performing reliable estimation of quality of motor oils and lubricating materials by accessible acid-base titration technique requiring no special instrumentation equipment.

EFFECT: simplified analytical procedure.

1 tbl

FIELD: chemical industry; petrochemical industry; analysis of the materials by the chemical methods.

SUBSTANCE: the invention is pertaining to the field of analysis of the materials by the chemical methods (by titration, with utilization of chemical indicators), containing the organic compounds of magnesium and may be used in chemical and a petrochemical industry at exercising control over the quality of petroleum. The invention provides, that magnesium chloride from the oil test is produced by impregnation of the ash-free filter with the tested oil with its subsequent incineration up to the complete ashing. Then the ash is dissolved in 30-40 cm^{3} of the weak 6 Mole/dm^{3} solution of hydrochloric acid. The produced solution id boiled within 15-20 minutes, transferred by a spray of the distilled water into the graduated flask. Take the aliquot, in which add the distilled water and neutralize it with ammonia (dropwise) up to pH=10.0, introduce the ammoniacal buffered solution and the indicating device the chromogen black ЕТ-100 and titrate 0.025 Mole/cm^{3} with the B-trilonum solution till the change of the a crimson-violet color into blue- pale blue, and quantity of magnesium (in mass%), is determined by the empirical formula. The invention allows to reduce the time duration for determination of the contents of magnesium, to improve the labor conditions due to exclusion from the process of the toxic and flammable benzole without reduction of requirements on toxicity and reliability of the produced results.

EFFECT: the invention ensures reduction of the time for determination of the contents of magnesium, improvement of the labor conditions, exclusion from the process of the toxic and flammable benzole without reduction of requirements to toxicity and reliability of the produced results.

2 tbl

FIELD: technical expertise of firearms, possible use in forensic evaluations and investigations, and also during field operations.

SUBSTANCE: method for determining remoteness of shot from a firearm includes taking samples of diphenylamine from internal surface of barrel of firearm being examined, absorption of diphenylamine by sorbent, following desorption of diphenylamine and measurement of its amount in samples, on basis of which remoteness of shot is determined. Prior to taking samples barrel of firearm is heated, two samples of diphenylamine are taken by suction. Second sample is taken after experimental shot from current firearm, performed directly after taking first sample in the moment of firearm receipt. Then ratio of amount of diphenylamine in second sample to its amount in first sample is calculated, and remoteness of shot is determined as a result of comparison of received ratio to analogical ratio for firearm with known shot remoteness value. Device for taking samples when determining firearm shot remoteness contains heating element, positioned on the barrel of weapon, aspirator, concentration shell, having a layer of sorbent inside, and an adapter for hermetic connection of barrel channel outlet to concentration shell, output of which is connected to aspirator.

EFFECT: increased precision when determining remoteness of a shot.

2 cl, 6 dwg

FIELD: analytical methods in petroleum industry.

SUBSTANCE: invention relates to analytical checking of crude oil, petroleum derivatives, and gas condensate quality. 2 to 5g sample is thermostatically controlled at 50-70°C, while simultaneously hydrogen sulfide and light mercaptans are for 2-5 min displaced by inert gas or air into in series arranged absorption solutions, namely sodium carbonate solution for determining hydrogen sulfide and sodium hydroxide solution for determining light mercaptans. After complete withdrawal of hydrogen sulfide and light mercaptans, their quantitative content is determined by means of iodometric titration method.

EFFECT: extended range of analyzed products, increased determination accuracy, shortened analytical procedure, and enabled carrying out analyses not only in stationary laboratory without deviation from standardized procedures.

1 dwg, 1 tbl

FIELD: explosives.

SUBSTANCE: invention provides marking additive containing marking substance foreign to explosive substance and preserving its properties under blast conditions. Marking substance is composed of at least one rare element of periodic system (e.g. lanthanide) and aluminum is used as microencapsulation substance. A method for preparing marking additive for explosive substance is proposed as well as a method to determine origin of explosive substance, into which additive was introduced, and also installation for determining spectral characteristics of chemical elements of marking additive in explosive substance.

EFFECT: enabled creation of marking additive suitable to develop coding system for explosive substance during production thereof in order to determine later manufacturer of explosive.

8 cl, 3 dwg

FIELD: technology for determining amount of natural gas being produced.

SUBSTANCE: gas counter is graduated as energy-measuring device and contains anemometer for determining mass flow of gas and block for processing results. Calibrating is performed on basis of basic gas mixture. During measurement of gas flow, measured value of energy consumption is multiplied by correction coefficient, which takes heat-creative ability of produced gas mixture into consideration. Aforementioned heat-creative ability is determined by external block.

EFFECT: inventions make it possible to determine by means of simple and cheap gas counter the actual energy consumption of expendable gas and to perform calculation of payment in accordance with produced quantity.

2 cl, 5 dwg

FIELD: petroleum derivative testing methods.

SUBSTANCE: invention, in particular, relates to estimating tendency of distillate and residual fuels for lacquer and carbon deposition as function of hydrocarbon type content, which can be used in research enterprises and refinery laboratories as well as in enterprises dealing with development and employment of motor fuels. Method according to invention comprises supplying fuel in droplet-liquid state at atmospheric pressure into air preheated to operation temperature of internal combustion engine with time intervals equal to free fall time of droplet, during which interval a droplet undergoes heating, vaporization, inflammation, burning, and thermal-oxidative conversion, after which mass of lacquer and coal deposits formed on heated plate made from catalytically active material and installed at an angle to fall axis of unburned droplet is measured, said angle of slope of plate before supply of fuel is selected within a range of Pα = 15-45° depending on hydrocarbon type content of fuels employed.

EFFECT: improved accuracy and reliability of test procedure.

1 dwg, 1 tbl

FIELD: petroleum processing.

SUBSTANCE: composition of reference fuel for determining cetane number of diesel fuel comprises 0 to 100% by volume of high-cetane and/or 0 to 100% by volume of low-cetane component, the former containing α-olefin fraction C_{14} with cetane number not below 75 and the latter propylene tetramers with cetane number not higher than 25.

EFFECT: increased accessibility and reduced toxicity as compared to known reference fuel, and also stabilized composition on storage, which ensures constancy of cetane number values and excludes necessity of additional checking.

3 tbl

FIELD: tests of powders and explosives.

SUBSTANCE: the device includes a two-layer metal body, steel obturating rings, device for measurement of pressure in the combustion chamber made in the form of a cover with a measuring cylinder, having at least two strain-measuring devices, bushes made of material with a high thermal diffusivity are installed at the inlet to the gas discharge duct in the ignition spacer and at the inlet to the pressure measuring device on the side of the combustion chamber, and the cavities behind the obturating rings are connected with the atmosphere through the discharge ducts.

EFFECT: enhanced service life of the manometric vessel.

1 dwg

FIELD: possible use for determining water presence level in product of oil wells.

SUBSTANCE: method for measuring mass concentration of water in water-oil-gas mixture includes taking of a sample of water-oil-gas mixture in hermetic cylinder-shaped vessel with given volume V and height H and measurement of hydrostatic pressure P_{1} at fixed values of temperature T and pressure P_{a} in aforementioned vessel. After measuring of hydrostatic pressure volume of vessel hollow is decreased until full solution of gas and hydrostatic pressure P_{2} is measured, and mass concentration of water W in water-oil-gas mixture is determined in accordance to mathematical expression , where g - free fall acceleration.

EFFECT: improved precision of measurements of mass concentration of water in liquid due to prevented influence of gas separation.

1 dwg

FIELD: devices for determination of impact sensitivity characteristics of explosives.

SUBSTANCE: the device has an anvil installed on a foundation and a load with vertical guides, the anvil is connected to the foundation by obliquely positioned plate springs.

EFFECT: enhanced accuracy of determination of sensitivity of explosives to a slanting impact, and, as a result, enhanced safety of handling of explosives.

2 cl, 1 dwg

FIELD: analytical methods in petroleum industry.

SUBSTANCE: invention relates to determining content of water and suspended impurities in aviation fuel and petroleum products, e.g. kerosene and aviation oils. Indicator element used in analytical procedures includes two layers of polymeric porous hydrophobic mixture with ultra-thin fiber structure, first one being impregnated with ferric sulfate solution. Both layers are impregnated with solutions based on the same solvent containing distilled water and ethyl cellosolve, dried, and attached to each other. Structure of ultra-thin fibers has specific packing density from 0.013 to 0.066 kg/m^{2}·mm Hg. First layer is impregnated with 6-9% ferric sulfate solution and second one with solution containing potassium ferricyanide and potassium ferrocyanide at their ratio 1:(25-35) in that layer. Solvent, in particular, contains 40-60 vol % distilled water, 30-50 vol % ethanol, and 5-15 vol % ethyl cellosolve.

EFFECT: accelerated indication and increased analytic accuracy at lower usage of porous base.

1 tbl

FIELD: investigating or analyzing materials.

SUBSTANCE: method comprises determining the values of the inform-parameter for various reference petrols, plotting calibration dependence of the inform-parameter on the octane number, determining the value of the inform-parameter of a sample of petrol to be analyzed, determining octane number of the petrol to be analyzed from the calibration curve, and measuring density and temperature of the sample. The value of the inform-parameter is determined from measuring the surface tension of the sample. The octane number is calculated within temperature range 10-40^{o}C.

EFFECT: enhanced accuracy of determining.

1 tbl cl, dwg