Computing device, computing method, and storage medium

Abstract

The present application provides a kind of in calculating the multiple physical property values associated with combustion gas can be calculated with simple and relatively low cost computing device, computing method and storage medium.The computing device is the computing device (1) for calculating the value associated with the combustible object gas containing impurity component, with: heat calculation unit (7), which is based on the conversion heat (H OPT ) obtained from the refractive index of object gas and the conversion heat (H SONIC ) obtained from density to calculate the heat (Hs) of the object gas;Impurity component total approximate concentration calculation unit (8), which is based on conversion heat (H OPT , H SONIC ) to calculate the approximate concentration (y) of impurity component;And hypothetical basic heat calculation unit (9), which is based on heat (Hs) and approximate concentration (y) to calculate the hypothetical basic heat (H' HC ) of object gas under the condition of assuming removing impurity component.

Description

Technical Field

[0001] The present invention relates to a computing device, a computing method, and a storage medium capable of calculating various values ​​related to the combustion of a target gas (e.g., natural gas). Background Technology

[0002] Regarding the treatment of flammable gases, there are numerous physical property values ​​that serve as indicators or benchmarks. Furthermore, various methods are used for each physical property value in relation to these calculation methods.

[0003] One of the physical properties of flammable gases is heat, but as a method for measuring heat, there are known methods that calculate the heat of the target gas based on heat converted from refractive index and heat converted from sound speed (for example, see Patent Document 1), wherein the heat converted from refractive index is obtained based on the heat of the target gas and the heat converted from sound speed is obtained based on the heat of the target gas.

[0004] In addition, other physical properties, such as compressibility coefficient and combustion rate, are typically calculated using methods based on international standards. In this case, input values ​​(parameters) are typically obtained from gas chromatography analysis.

[0005] As an example, it is well known that methods based on ISO 12213-2 and ISO 12213-3 are used to determine the compressibility factor of natural gas.

[0006] The calculation method based on ISO 12213-2 involves taking the pressure P, temperature T, and molar concentration x of the components of the gas constituting the natural gas. i A method to calculate the compression coefficient Z using the input value (input parameter).

[0007] In addition, the calculation method based on ISO 12213-3 uses the pressure P, temperature T, and heat Hs of natural gas (total calorific value in MJ / m³) as inputs. 3 The total calorific value is MJ / m³ 3 These values ​​are obtained by conversion under the conditions of a measurement reference temperature of 0℃, a combustion reference temperature of 25℃, and a pressure of 101.325 kPa; specific gravity d; and carbon dioxide gas concentration x. CO2 and hydrogen concentration x H2 As input parameters, the mole fraction x of hydrocarbon gases is calculated. CH Nitrogen mole fraction x N2 Mole fraction of carbon monoxide x CO The molar heat of equivalent hydrocarbon gases H CH The molar mass M of equivalent hydrocarbon gases CHSecond virtual conversion factor (Tn = 273.15K) Bn, molar density ρ under standard conditions m，n Mass density ρ under standard conditions n After using multiple items such as total calorific value Hs as intermediate data, the compression coefficient Z is calculated using these data.

[0008] In addition, the combustion rate (MCP) of city gas under normal conditions is usually calculated using the formula (Pa) shown below, based on the composition analysis values ​​from the gas chromatograph.

[0009] MCP=(1-K)×{Σ(Si·fi·Ai)} / {Σ(fi·Ai)}(Pa)

[0010] Si: Combustion rate of the combustible gas component i in the gas.

[0011] fi: Coefficients of the various flammable gas components i in the gas.

[0012] Ai: Volume percentage of each flammable gas component i in the gas.

[0013] K: Attenuation coefficient, calculated using the following formula.

[0014] K={ΣAi / (Σαi·Ai)}×{(2.5CO2+N2-3.77O2) / (100-4.77O2)+[(N2-3.77O2) / (100-4.77O2)] 2}

[0015] αi: Correction factor for the flammable gas component i in the gas.

[0016] CO2, N2, O2: Volume percentages of each component in a gas.

[0017] Existing technical documents

[0018] Patent documents

[0019] Patent Document 1: Japanese Patent No. 6402387 Summary of the Invention

[0020] Technical issues

[0021] However, if the physical properties (such as compression ratio, combustion rate, etc.) are different, the parameters used for calculation will also be different in many cases, and it is necessary to obtain the unit values ​​of each parameter. In addition, when many parameters are used, such as in the calculation of the compression ratio, the steps and apparatus involved in the calculation naturally become more complex.

[0022] Especially when calculating the compressibility factor, in calculation methods based on ISO 12213-2 and ISO 12213-3, with pressure P and temperature T as initial input data, calculating the compressibility factor under different temperature and pressure conditions requires recalculation based on all the input data required in each calculation method, which lacks convenience. Furthermore, when temperature and pressure cannot be measured, there is also the problem of not being able to obtain the numerical values ​​associated with the compressibility factor.

[0023] These problems also exist in the calculation of other physical properties (such as combustion rate). In particular, the calculation of combustion rate is costly and difficult to perform simply because it uses analytical values ​​obtained from large and expensive equipment, namely gas chromatography.

[0024] As a result, research on simple and low-cost methods, especially when calculating multiple types of physical properties, has stalled.

[0025] The present invention was made in view of the above-mentioned problems, and its object is to provide a computing device, computing method and storage medium that can perform calculations on multiple types of physical properties associated with combustion gases in a simple and relatively low cost.

[0026] Technical solution

[0027] This invention relates to a computing device for calculating values ​​associated with a target gas containing impurity components, characterized in that the computing device comprises: a heat calculation unit that calculates the heat of the target gas based on converted heat obtained from the refractive index and density of the target gas, respectively; an approximate concentration calculation unit for total impurity components that calculates an approximate concentration of the total impurity components based on the converted heat; and a hypothetical basic heat calculation unit that calculates the basic heat of the target gas (hereinafter referred to as "hypothetical basic heat") assuming that the impurity components have been removed, based on the heat and the approximate concentration.

[0028] In addition, the present invention relates to a calculation method for calculating values ​​associated with a target gas containing impurity components, characterized by comprising: a step of obtaining converted heat based on the refractive index and density of the target gas respectively; a step of calculating the heat of the target gas based on the converted heat; a step of calculating the total approximate concentration of the impurity components based on the converted heat; and a step of calculating the base heat of the target gas (hereinafter referred to as "hypothetical base heat") based on the heat and the total approximate concentration, assuming that the impurity components have been removed.

[0029] In addition, the present invention relates to a storage medium storing a program that enables a computer to perform the above-described calculation method.

[0030] Technical effect

[0031] According to the present invention, a computing device, a computing method, and a storage medium are provided that can perform the calculation of multiple types of physical properties associated with combustion gases in a simple and relatively low cost. Attached Figure Description

[0032] Figure 1 This is a block diagram illustrating an example of the computing device according to this embodiment.

[0033] Figure 2 This is a block diagram illustrating an example of the computing device according to this embodiment.

[0034] Figure 3 This is a flowchart illustrating an example of the calculation method of this embodiment.

[0035] Figure 4 This is a flowchart illustrating the method for calculating the compression coefficient in this embodiment.

[0036] Figure 5 This is a flowchart illustrating the method for calculating the combustion rate in this embodiment.

[0037] Figure 6 This is a graph illustrating an example of the relationship between the heat of a gas and its compressibility.

[0038] Figure 7 The result is a verification of the normalized compression coefficient calculated using this implementation method.

[0039] Figure 8 This is a graph comparing the correction coefficients for the effects of impurities.

[0040] Figure 9 This is a graph comparing the compression coefficient calculated by conventional methods with the compression coefficient calculated by the method of this embodiment.

[0041] Figure 10 This is a graph comparing the compression coefficient calculated by conventional methods with the compression coefficient calculated by the method of this embodiment.

[0042] Figure 11 This is a graph comparing the compression coefficient calculated by conventional methods with the compression coefficient calculated by the method of this embodiment.

[0043] Figure 12 This is a graph comparing the compression coefficient calculated by conventional methods with the compression coefficient calculated by the method of this embodiment.

[0044] Figure 13 This is a graph comparing the compression coefficient calculated by conventional methods with the compression coefficient calculated by the method of this embodiment.

[0045] Figure 14 This is a graph comparing the compression coefficient calculated by conventional methods with the compression coefficient calculated by the method of this embodiment.

[0046] Figure 15 (A) is a graph showing the relationship between the base heat (calculated value) of several natural gases and the combustion rate calculated by the MCP formula based on conventional methods.

[0047] Figure 15 (B) is a graph showing the relationship between the change in combustion rate and the basal heat for natural gas containing impurities.

[0048] Figure 16 A graph comparing the combustion rate calculated by conventional methods with the combustion rate calculated by the method of this embodiment is shown.

[0049] Symbol Explanation

[0050] 1. Computing device

[0051] 2. Refractive Index Conversion Heat Acquisition Unit

[0052] 3 Density conversion heat acquisition unit

[0053] 6. Error Correction Value Calculation Unit

[0054] 7. Heat Calculation Unit

[0055] 8. Approximate Concentration Calculation Unit for Total Mixed Gases

[0056] 9. Hypothetical Basic Heat Calculation Unit

[0057] 10 Heat Conversion Calculation Unit

[0058] 15. Property Value Calculation Unit

[0059] 15A Compression Coefficient Calculation Unit

[0060] 15B Combustion Rate Calculation Unit

[0061] 20 Output Units

[0062] 21 Refractive Index Measurement Unit

[0063] 31 Sound speed measurement unit

[0064] 41 Gas pipeline

[0065] 42 Gas Flow Path

[0066] 151 Normalized Compression Coefficient Calculation Unit

[0067] 152 General Formula Conversion Unit

[0068] Z compressibility

[0069] H' HC Hypothetical basal calories

[0070] N Normalized compressibility coefficient

[0071] Z compressibility

[0072] H OPT Refractive index to heat conversion

[0073] H SONIC Density to Heat Conversion Detailed Implementation

[0074] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. First, the computing device 1 of one embodiment of the present invention is a device for calculating values ​​associated with a combustible target gas containing impurity components. Here, the "values ​​associated with combustible target gas" in this embodiment are, for example, values ​​(physical property values, coefficients) associated with the combustion of the target gas (combustible gas), values ​​(physical property values, coefficients) associated with the state of the combustible gas, etc. Here, as an example, the case where the value (physical property value, coefficient) associated with the combustion of the combustible gas is the basal heat or a value related to the basal heat, the combustion rate, and the value (physical property value, coefficient) associated with the state of the combustible gas is a value related to the compressibility coefficient will be described.

[0075] Furthermore, the target gas in this embodiment is, for example, natural gas or biogas freshly produced from a gas field; as an example, it is natural gas containing impurities (non-flammable gases). Specifically, it is a gas whose main component is a first gas (flammable gas) and which contains a second gas (impurities, non-flammable gases) that constitutes a component of measurement error. More specifically, the first gas is, for example, an alkane-based hydrocarbon gas (e.g., methane (CH4), ethane (C2H6), propane (C3H8), butane (n-C4H4)) whose heat and refractive index, and heat and density have a specific correspondence (specifically, density is proportional to heat, and refractive index is proportional to heat). 10 (and other gases).

[0076] Furthermore, the second gas is a gas that constitutes a mixed gas, such as a gas whose heat and refractive index, as well as its heat and density, do not have a specific correspondence. A mixed gas refers to, for example, a gas that primarily contains nitrogen (N2) and carbon dioxide (CO2) (mixed together). Moreover, "a gas primarily containing nitrogen (N2) and carbon dioxide (CO2)" means a gas that does not contain any non-flammable gas components other than these two, does not contain any flammable gas components other than alkanes (e.g., hydrogen, carbon monoxide, etc.), or even if it contains non-flammable gases other than these two, the amount is so minute that it does not affect the calculation.

[0077] In addition, the calorific value Hs of natural gas described below refers to the total calorific value in MJ / m³. 3 The total calorific value is MJ / m³ 3 The values ​​are calculated under the conditions of a measurement reference temperature of 0℃, a combustion reference temperature of 0℃, and a pressure of 101.325 kPa. Furthermore, the concentrations of all gases are uniformly expressed as molar concentration [mol%].

[0078] <Computing Device>

[0079] Figure 1 This is a block diagram that briefly illustrates an example of the configuration of the computing device 1 according to the first embodiment. The computing device 1 of this embodiment, for example, calculates data along the gas line 41. Figure 1 The device for calculating the value associated with the object gas flowing in the direction of the arrow has a heat conversion calculation unit 10, a miscellaneous gas total approximate concentration calculation unit 8, a hypothetical basic heat calculation unit 9, and an output unit 20.

[0080] The heat conversion calculation unit 10 includes a refractive index heat conversion acquisition unit 2, a density heat conversion acquisition unit 3, an error correction value calculation unit 6, and a heat calculation unit 7. The heat conversion calculation unit 10 is a unit that outputs the heat of the target gas (converted heat) that takes into account the error caused by the impurity components by calculating the heat obtained by converting the heat obtained by converting the refractive index of the target gas (including impurity gas components) and the heat obtained by converting the density.

[0081] Gas pipeline 41 is connected to refractive index conversion heat acquisition unit 2 and density conversion heat acquisition unit 3 via gas flow path 42. The target gas in gas pipeline 41 is supplied to refractive index conversion heat acquisition unit 2 and density conversion heat acquisition unit 3. The computing device 1 is, for example, disposed in an explosion-proof container (not shown).

[0082] The refractive index conversion heat acquisition unit 2 detects the difference in refractive index of light between the target gas and a standard gas such as air as the displacement of interference fringes by using a signal (voltage applied to the refractive index conversion heat acquisition unit 2) output from an external device (power supply device, etc.) 4. Based on the displacement of these interference fringes, it acquires the refractive index conversion heat H of the target gas. OPT Devices with a structure (such as interferometers, refractive index calorimeters, etc.).

[0083] The refractive index-to-heat acquisition unit 2 includes, for example, a refractive index measuring unit 21 (e.g., a photosensitive sensor) that measures the refractive index of the target gas; and a refractive index-to-heat conversion processing unit 22 that calculates the refractive index-to-heat H based on the refractive index value measured by the refractive index measuring unit 21. OPT The function.

[0084] The refractive index-heat conversion processing unit 22 has a predetermined correlation formula based on pre-obtained refractive index and heat for gases consisting only of a reference combustible gas component (alkane-based hydrocarbon gas) (gases without impurity components). Then, assuming that the measured refractive index value for the target gas is the refractive index of the combustible gas, the refractive index-calorific value H of the target gas is calculated by comparing the measured refractive index value with the correlation formula. OPT .

[0085] The density-to-heat acquisition unit 3 measures the speed of sound of the target gas and acquires the density-to-heat H of the target gas by means of a signal (voltage applied to the density-to-heat acquisition unit 3) output from, for example, an external device (power supply, etc.) 5. SONIC A device with a structure.

[0086] The density-to-heat acquisition unit 3 includes: a sound velocity measurement unit (e.g., a sound velocity sensor) 31, which measures the propagation speed of sound waves in the target gas (the speed of sound of the target gas); and a density-to-heat conversion processing unit, which calculates the density of the target gas based on the speed of sound measured by the sound velocity measurement unit 31 and determines the density-to-heat H. SONIC .

[0087] The density-heat conversion processing unit has a predetermined correlation formula for gases consisting solely of a reference combustible gas (alkane-based hydrocarbon gas) (gases without impurities), based on pre-obtained density (speed of sound) and heat. Then, assuming the measured density of the target gas is the density of the combustible gas, the density-to-heat H of the target gas is calculated by comparing the measured density value with this correlation formula. SONIC .

[0088] Error correction calculation unit 6 calculates the value that corrects the error in the heat calculation (error caused by impurities) (error correction value: the second term on the right side of equation (7) described later), the error in the heat calculation is caused by the presence of impurities (nitrogen and carbon dioxide) in the target gas.

[0089] The heat calculation unit 7 has a conversion heat calculation formula (formula (7) described later), which is based on the conversion heat obtained from the refractive index and density of the target gas (the refractive index conversion heat H mentioned above). OPT Heat conversion from density (H) SONIC The unit calculates the heat Hs of the target gas through a predetermined calculation, including the error correction value. This predetermined calculation is a calculation (heat conversion calculation) independently developed by the applicant of this application, hereinafter referred to as the OPT-SONIC calculation.

[0090] The approximate concentration calculation unit 8 for total impurity gases has a formula for calculating the approximate concentration of total impurity gases (formula (8)) described below), which is based on the heat H converted from refractive index. OPT Heat conversion from density (H) SONIC This unit calculates the approximate total concentration (approximate total concentration y) of the impurity components in the target gas. For the target gas processed in this embodiment, nitrogen and carbon dioxide are the main impurity components. Furthermore, even if the individual concentrations of these impurity components are not clearly defined, these concentrations are replaced with a total concentration that allows for approximate error during various calculations. The total concentration of the impurity components that allows for this approximate error is the approximate total concentration y. The approximate total concentration calculation unit 8 can calculate the heat H based on the refractive index. OPT Heat conversion from density (H) SONIC To calculate the approximate total concentration of the mixed gas components (nitrogen and carbon dioxide) (approximate total concentration y of mixed gas).

[0091] The hypothetical basic heat calculation unit 9 has a hypothetical basic heat calculation formula (formula (9) described later). For impurities with unclear concentrations (nitrogen, carbon dioxide), their total concentration is assumed to be an approximate total concentration y of the impurities. The basic heat of the target gas (i.e., the heat of only the combustible gas components in the target gas) H' is calculated by excluding the impurities based on this assumption. HC .

[0092] Here, the "basic heat" of the target gas refers to the heat of the target gas when it consists only of combustible gases (alkane-based hydrocarbon gases). When the target gas contains impurities, these impurities are removed before measurement (calculation). Therefore (details will be described later), it would normally be necessary to measure the concentration of the impurities. Even if the concentration of the impurities is unknown, the hypothetical basic heat calculation unit 9 of this application calculates a value equivalent to the basic heat through calculation. Specifically, based on the heat Hs of the target gas calculated by the heat calculation unit 7 and the approximate total concentration y of the impurities calculated by the approximate total concentration calculation unit 8, a value corresponding to the basic heat of the target gas (i.e., the heat of only combustible gas components in the target gas) under the assumption that impurities have been removed is obtained through calculation. In this embodiment, the value equivalent to the basic heat calculated by the hypothetical basic heat calculation unit 9 is referred to as the hypothetical basic heat H'. HC Output unit 20 outputs the hypothetical basic heat H' HC .

[0093] Generally, determining the concentration of impurity gas components using gas chromatography or similar instruments is a large-scale and complex operation. However, according to the computing device 1 of this embodiment, as long as the refractive index and speed of sound of the target gas (containing impurity gas components) can be measured as input, the heat of only combustible gases (hypothetical basic heat H') in the target gas can be calculated even if the concentration of impurity gas components is unclear. HC ).

[0094] The hypothetical basic heat H' is the result of the calculation output by computing device 1. HC It serves as a substitute for the fundamental heat of the target gas. That is, in the calculation of various physical properties (e.g., compressibility, combustion rate, etc.) that can be calculated using fundamental heat, the hypothetical fundamental heat H' can be utilized. HC The rationale for this substitution will be detailed later, but the refractive index measuring unit (refractive index calorimeter) and the sound velocity measuring unit (sound velocity sensor) are typically small and relatively inexpensive devices. Therefore, compared to previous methods (calculation of compressibility based on ISO 12213-3, and calculation of combustion rate based on formula (Pa), it is simpler and easier to calculate the physical properties related to natural gas.

[0095] Figure 2 This is a schematic diagram showing an example of a computing device 1 equipped with a property value calculation unit 15, which calculates property values ​​using a hypothetical basic heat H' HC Calculate various physical properties related to the target gas. Figure 1 Configurations shown that are identical are indicated by the same reference numerals, and descriptions are omitted. Furthermore, the configurations other than the property value calculation unit 15 are the same as... Figure 1 same. Figure 2 (A) is a block diagram showing the configuration of the entire computing device 1. Figure 2 (B) Figure 2 (C) is a block diagram showing an example of the property value calculation unit 15.

[0096] Figure 2 (B) is an example of a case where the property value calculation unit 15 is a compression coefficient calculation unit 15A that calculates the compression coefficient. The compression coefficient calculation unit 15A has a unit (normalized compression coefficient calculation unit) 151 that calculates the normalized compression coefficient (hereinafter referred to as "normalized compression coefficient") N and a general formula conversion unit 152 that converts the normalized compression coefficient N into a general formula.

[0097] The normalized compressibility factor N will be described in detail later, but the compressibility factor of a gas, which would otherwise be a function of temperature T and pressure P, is normalized in a way that is unaffected by temperature T and pressure P. The normalized compressibility factor calculation unit 151 has a normalized compressibility factor calculation formula (equation (10) described later), which is obtained by using the hypothetical basic heat H' HC The normalized compressibility coefficient N is calculated by combining the total approximate concentration y of the impurity gases. The normalized compressibility coefficient calculation unit 151 corrects for errors arising from the use of the total approximate concentration y of the impurity gases and calculates the normalized compressibility coefficient N (this correction will be described later). The compressibility coefficient calculation unit 15A receives inputs of pressure P and temperature T, generalizes the normalized compressibility coefficient N using the general formula conversion unit 152, and calculates the compressibility coefficient Z under the required pressure P and temperature T conditions.

[0098] Figure 2 (C) is an example of a combustion rate calculation unit 15B used to calculate the combustion rate MCP, where the physical property calculation unit 15 is the combustion rate calculation unit 15B. The combustion rate calculation unit 15B has a combustion rate calculation formula (formula (15) described later) and uses the hypothetical basic heat H' HC The combustion rate MCP is calculated by combining the total approximate concentration y of the mixed gases. The combustion rate calculation unit 15B corrects for errors caused by using the total approximate concentration y of the mixed gases and calculates the combustion rate MCP (this correction will be described later).

[0099] Thus, the computing device 1 of this embodiment obtains the refractive index conversion heat H. OPT Heat conversion from density (H) SONIC These two variables are used to calculate the hypothetical basal heat H' using the OPT-SONIC operation. HC Additionally, by using the hypothetical basal heat H' HC This allows for the approximate calculation of several physical properties related to natural gas.

[0100] In particular, when the physical property values ​​are values ​​that can be calculated using the basic calorific value of natural gas, they can be directly substituted. For example, according to the applicant's original method, which will be described in detail later, as a first method, physical property values ​​such as compressibility coefficient and combustion rate can be calculated using a polynomial (3 input values ​​(input parameters)) of three variables: the basic calorific value of natural gas, the concentration of carbon dioxide gas as a mixed gas component, and the concentration of nitrogen gas. That is, calculations can be performed more easily with a simpler structure than calculation methods based on conventional methods such as ISO 12213-3, using formulas (Pa). Furthermore, as a second method, according to the above-described embodiment, by substituting a hypothetical basic calorific value for the basic calorific value, physical property values ​​such as compressibility coefficient and combustion rate can be calculated using the two input values ​​of the target gas's refractive index and density. That is, when calculating the same physical property values, the number of input parameters can be reduced even compared to the first method. In addition, the determination of the target gas's refractive index and density can be carried out using a small and relatively inexpensive device, and the basic calorific value H that can be used can be calculated simply and easily. HC To calculate multiple physical property values ​​related to natural gas.

[0101] <Calculation Methods and Procedures>

[0102] Additionally, refer to Figure 3 Embodiments of the present invention provide a method for calculating physical property values ​​associated with a target gas containing impurity gas components. Specifically, as Figure 3 As shown in (A), the calculation method has the following steps: determining the refractive index of the target gas and obtaining the refractive index-converted heat H. OPT Step S01: Determine the density of the target gas and obtain the density-to-calorific-heat H. SONIC Step (Step S03); Calculate heat H based on refractive index OPT Heat conversion from density (H) SONIC The step of calculating the heat Hs of the target gas using OPT-SONIC calculation (step S05); and the heat H based on refractive index conversion. OPT Heat conversion from density (H) SONIC The steps include: calculating the approximate concentration of the impurity gas components (approximate total impurity gas concentration y) using the formula for calculating the approximate total impurity gas concentration (step S07); and calculating the hypothetical basic heat H' of the target gas using the formula for calculating the hypothetical basic heat based on the heat Hs of the target gas and the approximate total impurity gas concentration y. HC Step (Step S09). Calculate the hypothetical basal heat H' HC For example, it can be used based on the basal heat H of the target gas. HC Calculation of various physical property values ​​obtained (step S11).

[0103] like Figure 3 As shown in (B), as an example of a physical property value, in the case of calculating the compressibility coefficient Z, based on... Figure 3 The approximate total concentration y of the impurities calculated in step S07 of (A) and in Figure 3 The hypothetical basal heat H' calculated in step S09 of (A) HC To calculate the normalized compressibility factor N. In the calculation of the normalized compressibility factor N, the composition of the impurity gas (carbon dioxide concentration x) is considered. CO2 Correct the error caused by using the approximate concentration y of the total mixed gas (perform error correction) (step S111).

[0104] Next, the normalized compressibility coefficient N is converted into a general formula for the compressibility coefficient with temperature T and pressure P as parameters (function Z(T, P)) (step S112).

[0105] Then, input the arbitrary temperature T and pressure P into the general formula (function Z(T, P)) to calculate the compressibility coefficient Z (step S113).

[0106] like Figure 3 As shown in (C), as an example of physical property values, in calculating the combustion rate, based on the approximate total concentration of impurities y and the hypothetical basic heat H', HC The combustion rate is calculated using a formula. In the calculation of the combustion rate, errors arising from the use of an approximate concentration y of mixed gases are corrected (error correction is performed).

[0107] Furthermore, this embodiment of the present invention provides a program for causing a computer to execute the above-described calculation method.

[0108] <Methods for calculating physical property values ​​that can reduce the number of input parameters>

[0109] Next, as another embodiment of the present invention, a method that reduces the number of input parameters compared to conventional methods (e.g., the calculation method of ISO 12213-3, the method based on formula (Pa)) will be described in the calculation methods for the compressibility coefficient and combustion rate of the target gas. When the target gas is, for example, natural gas (paraffinic hydrocarbon gas) whose main impurity components are nitrogen and carbon dioxide (containing no hydrogen, carbon monoxide, or present in negligible amounts), its compressibility coefficient and combustion rate can be calculated using the following methods.

[0110] <Methods for Calculating Compression Coefficient>

[0111] Figure 4 (A) is a flowchart illustrating a first method for calculating the compression factor Z. Figure 4(B) is a flowchart illustrating the second method for calculating the compression coefficient Z.

[0112] (Compression factor calculation / First method)

[0113] The first method is to use the heat (Hs) of natural gas and the carbon dioxide concentration (x). CO2 Nitrogen concentration x N2 This method uses these three input parameters to calculate the compressibility factor Z. The method includes the following steps: inputting the calorific value of the natural gas (Hs), the carbon dioxide concentration (x)... CO2 and nitrogen concentration x N2 As input, the steps are as follows: (step S201) to calculate the normalized compressibility coefficient N using the normalized compressibility coefficient calculation formula (formula (5) described later); (step S203) to convert the normalized compressibility coefficient N into a general formula for compressibility coefficient (function Z(T, P)) with pressure P and temperature T as parameters; and (step S205) to calculate the compressibility coefficient Z under the required pressure P and temperature T conditions.

[0114] The compressibility factor Z, calculated using the method based on ISO 12213-3, is given by temperature T, pressure P, and heat Hs (total calorific value in MJ / m³). 3 The total calorific value is MJ / m³ 3 These values ​​are obtained by conversion under the conditions of a measurement reference temperature of 0℃, a combustion reference temperature of 25℃, and a pressure of 101.325 kPa; specific gravity d; and carbon dioxide gas concentration x. CO2 The function (function Z(T, P, Hs, d, x)) CO2 The value is expressed as follows. The applicant of this application has determined the compressibility coefficient Z of two different gases, A and B. A (T, P, Hs, d, x) CO2 Z B (T, P, Hs, d, x) CO2 The system attempts to normalize the coefficient of compressibility Z by setting its solutions to 0 or -1. The result is that the compressibility coefficient Z can be determined using the base heat Hs based on the calorific value of natural gas. HC Carbon dioxide gas concentration x CO2 and nitrogen concentration x N2 The polynomial (referred to later as equation (5)) is used to approximate the expression. The value obtained from this polynomial is the normalized compression coefficient N.

[0115] In previous methods (based on the calculation method of ISO12213-3), pressure P and temperature T were the initial input data. When calculating the compressibility coefficient Z under different temperature and pressure conditions, it is necessary to recalculate based on all the input data required in each calculation method, which lacks convenience.

[0116] The first method, based on the compressibility coefficient calculation, utilizes the calorific value Hs of natural gas and the carbon dioxide concentration x in the natural gas. CO2 and nitrogen concentration x N2 These three input parameters are used to calculate the normalized compressibility coefficient N, which is independent of temperature T and pressure P. In this case, equations (5) and (6) described later are used. Furthermore, the normalized compressibility coefficient N is converted into a general formula (function Z(T, P)) with temperature T and pressure P as parameters. That is, when calculating the compressibility coefficient Z under different temperature and pressure conditions, various compressibility coefficients Z can be calculated simply by changing the input parameters of temperature T and pressure P in the general formula (function Z(T, P)).

[0117] That is, the first method for calculating the compressibility factor is based on the calorific value of natural gas (Hs) and the concentration of carbon dioxide gas in natural gas (x). CO2 and nitrogen concentration x N2 Calculate the basic heat H HC According to the basic heat H HC Carbon dioxide concentration x in natural gas CO2 and nitrogen concentration x N2 A method for calculating the normalized compression factor N, and then calculating the compression factor Z based on the normalized compression factor N.

[0118] (Compression factor calculation / Second method)

[0119] Reference Figure 4 Section (B) describes a second method for calculating the compressibility factor Z. This second method further reduces the number of input parameters, calculating the compressibility factor Z based on the refractive index and density of natural gas. Specifically, it includes: calculating the refractive index-converted heat H based on the refractive index. OPT Step S301: Calculate the heat H based on density conversion. SONIC Step (Step S303); Calculate heat H based on refractive index OPT Heat conversion from density (H) SONIC The steps are as follows: calculating the calorific value Hs of natural gas using the OPT-SONIC formula (step S305); calculating the approximate total concentration y of mixed gases (step S307); and calculating the hypothetical basic calorific value H'. HC The steps are as follows: (Step S309); (Step S311) calculating the normalized compressibility coefficient N; (Step S313) converting the normalized compressibility coefficient N into a general formula (function Z(T, P)) with pressure P and temperature T as parameters; and (Step S315) inputting the required pressure P and temperature T into the general formula (function Z(T, P)) to calculate the compressibility coefficient Z.

[0120] The second method for calculating the compressibility factor is equivalent to the one described above. Figure 3 (A) Figure 3 The method for calculating the compressibility coefficient Z as a physical property value, as described in (B), allows for the calculation of the normalized compressibility coefficient N, independent of temperature T and pressure P, using the refractive index and density of natural gas as input parameters. In this case, equation (10) described later is used. Then, the normalized compressibility coefficient N is converted into a general formula (function Z(T, P)) with pressure P and temperature T as parameters. That is, when calculating the compressibility coefficient Z under different temperature and pressure conditions, various compressibility coefficients Z can be calculated simply by changing the input parameters of temperature T and pressure P in the function Z(T, P).

[0121] Alternatively, a compressibility coefficient calculation apparatus capable of performing the above-described method can also be constructed. That is, although the illustration is omitted, the compressibility coefficient calculation apparatus capable of performing the first method of compressibility coefficient calculation includes: an acquisition unit capable of acquiring the calorific value Hs of the natural gas and the carbon dioxide gas concentration x, respectively. CO2 Nitrogen concentration x N2 The calculation unit is based on the heat Hs and the carbon dioxide gas concentration x. CO2 Nitrogen concentration x N2 Calculate the basic heat H HC The system includes a normalized compression coefficient calculation unit with a normalized compression coefficient calculation formula; a conversion unit that converts the normalized compression coefficient to the general compression coefficient formula (function Z(T, P)); and an output unit that outputs the calculated compression coefficient Z. Alternatively, a program can be configured to enable a computer to execute the above method.

[0122] Furthermore, the compressibility calculation apparatus and program capable of performing the second method for calculating the compressibility coefficient are the same as those described above. Figure 2 (A) Figure 2 The computing device 1 described in (B) is the same, and the description is omitted.

[0123] <Methods for Calculating Combustion Rate>

[0124] Next, refer to Figure 5 The method for calculating combustion rate is explained. Figure 5 (A) is a flowchart illustrating a first method for calculating combustion rate. Figure 5 (B) is a flowchart illustrating a second method for calculating the combustion rate.

[0125] (Combustion rate calculation / First method)

[0126] The first method for calculating combustion rate is to use the calorific value of natural gas (Hs) and the carbon dioxide concentration (x). CO2 Nitrogen concentration x N2These three input parameters are used to calculate the combustion rate MCP using the combustion rate calculation formula (13) shown below (and formula (14)).

[0127] Specifically, the first method for calculating the combustion rate is based on the calorific value of natural gas (Hs) and the carbon dioxide concentration in the natural gas (x). CO2 and nitrogen concentration x N2 To calculate the basic heat H HC According to the basic heat H HC Carbon dioxide concentration x in natural gas CO2 and nitrogen concentration x N2 A method for calculating the combustion rate MCP.

[0128] (Combustion rate calculation / Second method)

[0129] Reference Figure 5 Section (B) describes a second method for calculating the combustion rate MCP. This second method further reduces the number of input parameters by calculating the combustion rate MCP based on the refractive index and density of natural gas. Specifically, this method includes: calculating the refractive index-converted heat H based on the refractive index. OPT Step S401: Calculate the heat H based on density conversion. SONIC Step (Step S403); Calculate heat H based on refractive index OPT Heat conversion from density (H) SONIC The steps include: calculating the calorific value Hs of natural gas using the OPT-SONIC formula (step S405); calculating the approximate total concentration y of mixed gases (step S407); and calculating the hypothetical basic calorific value H'. HC The steps (step S409) and the steps (step S411) for calculating the combustion rate MCP by the combustion rate calculation formula shown in equation (15) described later.

[0130] This second method is equivalent to determining the combustion rate as described above. Figure 3 (A) Figure 3 The method for calculating the physical property values ​​described in (C) allows for the calculation of the combustion rate MCP using the two input parameters of the refractive index and density of natural gas, according to the second method.

[0131] Alternatively, a combustion rate calculation device capable of performing the above-described method can also be configured. That is, although not illustrated, the combustion rate calculation device capable of performing the first method of combustion rate calculation includes: an acquisition unit capable of acquiring the calorific value Hs of the natural gas and the carbon dioxide gas concentration x, respectively. CO2 Nitrogen concentration x N2 Based on heat Hs and carbon dioxide gas concentration x CO2 Nitrogen concentration xN2 Calculate the basic heat H HC The system includes a combustion rate calculation unit having a combustion rate calculation formula and an output unit that outputs the calculated combustion rate MCP. Alternatively, a program can be configured to cause the computer to execute the above method.

[0132] Furthermore, the combustion rate calculation device and program capable of performing the second method of combustion rate calculation are the same as those described above. Figure 2 (A) Figure 2 The computing device 1 described in (C) is the same, and the description is omitted.

[0133] Next, a detailed description will be given of the simulation and examination of the above-described embodiments that the applicant of this application could conceive of, as well as the calculation formulas (functions) derived therefrom.

[0134] <Normalized compression factor N>

[0135] This application explains the concept of the normalized compressibility factor N and its calculation method, as conceived by the applicant. The natural gas referred to below is a gas primarily composed of alkane hydrocarbons.

[0136] First, using the compressibility factor Z calculation method based on ISO 12213-3, the compressibility factor Z of natural gas composed solely of alkane hydrocarbons with CH4 as the main component is calculated. HC The characteristics of [the material] were studied. Under these conditions, the compressibility coefficient Z was determined. HC (P, T) depends on heat H independently of its components. HC And it changes. That is, as shown in equation (1) below, the compressibility coefficient Z of natural gas HC The ability to convert heat (in the following explanation, this means basal calorific value) H HC It is expressed as a polynomial (a function determined by pressure P and temperature T).

[0137] [Mathematical Expression 1]

[0138]

[0139] Here, a in equation (1) h (a3, a2, a1, a0) are the coefficients of each term in the polynomial.

[0140] Figure 6 This shows the heat H of the gas represented by equation (1). HC With compressibility coefficient Z HC A graph illustrating the relationship between the two. The horizontal axis represents the heat (H) of a gas composed solely of alkane-based hydrocarbons. HCThe vertical axis represents the compressibility Z under conditions of 7 MPa pressure and 20°C. HC .

[0141] Here, as alkane-based hydrocarbon gases, methane (CH4) containing ethane (C2H6), propane (C3H8), and butane (C4H4) in different proportions is considered. 10 For the mixture of these three gases, the heat Ht under the conditions of 7 MPa pressure and 20 °C is calculated based on ISO 6976. HC In addition, the compressibility coefficient Z was calculated using the calculation method of ISO 12213-3 under the conditions of pressure 7 MPa and temperature 20 °C. HC As a result, the heat H HC With compressibility coefficient Z HC The correlations between them are roughly consistent (in this figure, the curves representing the three relationships roughly overlap). That is, these correlations can be expressed using heat H as shown in equation (2) below. HC Represent it as a polynomial.

[0142] [Mathematical Expression 2]

[0143]

[0144] Here, the applicant of this application studies how to represent heat H in a relationship independent of pressure P and temperature T. HC With compressibility coefficient Z HC The relationship between them. Moreover, for those with Figure 6 The correlation shown refers to two gases A and B with different calorific values ​​(e.g., the calorific value of gas A < the calorific value of gas B), so that the compressibility coefficient Z for gas A is... A (T, P), compressibility coefficient Z of gas B B The solutions for (T, P) are 0 and -1 respectively. Equation (3) is used to attempt to normalize the compression coefficient.

[0145] [Mathematical Expression 3]

[0146]

[0147] As an example, let gas A be the heat H. HC It is 39.933 MJ / m 3 The gas (pure methane, CH4 = 100%) is represented by gas B, with heat H as the heat source. HC It is 46.547 MJ / m 3 The gas (CH4:C2H6:C3H8:C4H) 10 = 86:8:4:2 (gases with a composition of 86:8:4:2), so that the compressibility coefficient Z for these gases A is... 39.933MJ(T, P), compressibility coefficient Z of gas B 46.547MJ J The compression coefficient is normalized using equation (3) with solutions of 0 and -1 for (T, P).

[0148] The result is, as shown in equation (4-1) below, that the normalized value (N) is expressed in terms of heat H only. HC The function is approximated.

[0149] [Mathematical Expression 4]

[0150]

[0151]

[0152] Thus, when natural gas consists only of alkane-based hydrocarbon gases, it is possible to utilize heat H that is independent of pressure P and temperature T. HC The result (N) obtained by normalizing the compressibility coefficient Z is expressed as a polynomial. Hereinafter, this result (N) will be referred to as the "normalized compressibility coefficient N". It should be noted that the normalized compressibility coefficient N in the mathematical formula is marked with the corresponding heat values ​​of gas A and gas B (subscript: 46.547MJ, subscript: 39.933MJ) (N^{46.547MJ}_{39.933MJ}), but in the following explanation, the markings are omitted and it is simply referred to as "N".

[0153] Figure 7 The normalized compressibility coefficient N, calculated using equation (4), is the verification result, showing the heat H under different pressure P and temperature T conditions. HC The graph shows the relationship between the measured value and the normalized compression factor N. Figure 7 (A) represents the case where the pressure is 1 MPa. Figure 7 (B) represents the case where the pressure is 2 MPa. Figure 7 (C) represents the case where the pressure is 5 MPa. Figure 7 (D) represents a pressure of 10 MPa. Using calculations based on ISO 6976, determine the calorific value (H) of natural gas (a gas composed solely of alkane hydrocarbons) at temperatures of -20°C, 0°C, 20°C, 40°C, and 60°C. HC Furthermore, the normalized compressibility coefficient N under the above conditions is calculated using equation (4). The horizontal axis represents heat H. HC The vertical axis represents the normalized compressibility coefficient N. Even at pressure P and temperature T... Figure 7 Under any of the conditions shown, the curves representing the correlation between the two can be represented by approximately the same curve. Based on this result, it can be concluded that when natural gas consists only of alkane hydrocarbons, the normalized compressibility coefficient N can be expressed as a function of heat H.HC The polynomial (4-1) is roughly represented.

[0154] Next, for the heat H consisting only of alkane-based hydrocarbon gases HC Normalized compression factor N HC Regarding the gas, the study investigated the application of x N2 [mol%] of nitrogen and x CO2 In the case of [mol%] carbon dioxide gas, the normalized compressibility coefficient N HC The impact.

[0155] The result is that it was found that for the application of x N2 [mol%] of nitrogen gas, with x applied CO2 The normalized compressibility coefficient N(x) of natural gas in the case of [mol%] carbon dioxide gas. N2 ,x CO2 It will not be significantly affected by pressure P and temperature T, as shown in equation (5) below, with the heat H of the alkane-based hydrocarbon gas components. HC The function is approximated.

[0156] [Mathematical Expression 5]

[0157]

[0158] in,

[0159]

[0160]

[0161] Here,

[0162] a N2 =0.000139157, b N2 =0.00972504, c N2 =0.189587

[0163]

[0164] k N2 This is a correction factor (N2 correction factor) used to adjust for changes caused by the presence of nitrogen as an impurity in natural gas (the effect of nitrogen as an impurity), k. CO2 These are coefficients (CO2 correction coefficients) used to correct for changes caused by the inclusion of carbon dioxide as a stray gas component in natural gas (the effect of carbon dioxide as a stray gas). N2 k CO2 Alternatively, the heat H of the alkane hydrocarbon gas components in natural gas can be used. HCIt is represented by a polynomial approximation.

[0165] It should be noted that, although repeated, the heat H mentioned in the explanation up to this point... HC This represents the heat of natural gas when it consists only of alkane hydrocarbons, or, in the case of natural gas containing other gases (nitrogen and carbon dioxide), the heat of the alkane hydrocarbons in the natural gas excluding those other gases (i.e., the basic heat of natural gas, H). HC ).

[0166] Here, natural gas contains nitrogen (nitrogen concentration x) N2 [mol%]) and carbon dioxide gas (carbon dioxide gas concentration is x) CO2 When [mol%]) is used as a mixed gas component, the total calorific value Hs and the basal calorific value Hs of the natural gas are expressed by the following equation (6). HC The relationship between them.

[0167] [Mathematical Expression 6]

[0168]

[0169] That is, equation (5) is the formula for calculating the heat Hs of natural gas and the carbon dioxide concentration x using equation (6). CO2 Nitrogen concentration x N2 The formula for calculating the normalized compressibility coefficient N, which is unaffected by pressure P and temperature T, is as follows: For natural gas containing impurities, if the calorific value (total calorific value) Hs and the carbon dioxide concentration x of the natural gas can be obtained... CO2 Nitrogen concentration x N2 Therefore, it can be said that the basic heat H can be calculated using equation (6). HC The normalized compressibility factor N of the natural gas is calculated using equation (5).

[0170] Based on this investigation, and referring to the above... Figure 4 (A) In the normalized compressibility coefficient calculation method described, the heat (total heat) of the target gas (natural gas) Hs and the carbon dioxide gas concentration x are used. CO2 Nitrogen concentration x N2 These three elements are used as input parameters, and the normalized compressibility coefficient N is calculated using the above equations (5) (and (6)). By introducing the concept of normalized compressibility coefficient N, the compressibility coefficient can be calculated by arbitrarily changing only the pressure P and temperature T, based on the general formula for calculating the compressibility coefficient Z.

[0171] <Method for calculating compression factor using OPT-SONIC operation>

[0172] exist Figure 4 In the normalized compressibility calculation method shown in (A), the concentration of carbon dioxide gas as a component of the impurity gas, x, needs to be factored in. CO2 and nitrogen concentration x N2 (i.e., their measurements) are used as input parameters. The applicant of this application further investigated a method for calculating the compressibility factor Z using OPT-SONIC calculation without separately measuring the concentration of stray gas components.

[0173] This has already been explained; in OPT-SONIC calculations, heat (H) can be calculated based on the refractive index. OPT Heat conversion from density (H) SONIC The heat Hs is calculated using the conversion heat calculation formula (OPT-SONIC formula) shown in equation (7) below, and the refractive index conversion heat H is obtained based on the refractive index of the target gas, for example, measured by an optical sensor. OPT The density-converted heat H is calculated based on the density of the target gas, for example, measured by a sound speed sensor. SONIC That is, the following formula (7) represents the expression referring to the above. Figures 1 to 5 The formula for converting heat (OPT-SONIC formula) is explained.

[0174] [Mathematical Expression 7]

[0175]

[0176] Here, the second term on the right-hand side of equation (7) represents the refractive index equivalent heat H caused by the presence of impurities. OPT The values ​​of the included error components are based on the above. Figures 1 to 5 The explanation refers to the "error correction value". Furthermore, if we consider α in the second term on the right to be a value within a certain range (the range of a certain type of gas), it can be said to be a correction coefficient that is approximately constant regardless of the type of impurity gas. For example, the value of the correction coefficient α is in the range of α = 1.5 to 3.5.

[0177] Furthermore, based on the applicant's findings, it was determined that, assuming the only impurities in natural gas are nitrogen and carbon dioxide, as shown in equation (8) below, the second term on the right side of equation (7) is related to the nitrogen concentration x. N2 The value and the carbon dioxide gas concentration x CO2 The sum of the values ​​obtained by multiplying by 1.56 is proportional. It should be noted that, as impurity gas components, it is assumed that even if components other than nitrogen and carbon dioxide (such as hydrogen, carbon monoxide, etc.) are included, the proportion of components other than nitrogen and carbon dioxide in natural gas is negligible and is considered not to affect the calculated values ​​in this study (the same applies below).

[0178] [Mathematical Expression 8]

[0179]

[0180] That is, by taking the result of equation (8) as a variable y, and transforming the variable y and substituting it into the right side of equation (6), it is possible to calculate the basic heat H in equation (6). HC The corresponding value (as shown in equation (9) below). This variable y is the approximate concentration of the total nitrogen and carbon dioxide gases, i.e., referring to the above... Figures 1 to 5 The “approximate total concentration y of the impurities” explained is given by equation (8), which is the formula for calculating the approximate total concentration of the impurities. As shown in equation (8), this “approximate total concentration y of the impurities” can be calculated using the OPT-SONIC calculation. That is, even if the concentration of the impurity components (nitrogen concentration x) is... N2 Carbon dioxide gas concentration x CO2 Even when the concentrations of impurity gases are not clearly defined (i.e., the concentration of impurity gases is not measured), heat (H) can still be calculated based on the refractive index. OPT Heat conversion from density (H) SONIC To calculate the approximate total concentration y of the mixed gases. Additionally, regarding equation (6), if we replace the nitrogen concentration x... N2 and carbon dioxide gas concentration x CO2 The carbon dioxide concentration x CO2 When the value is approximately 1.56 times the actual value, and the approximation error is allowed while the total concentration of the mixed gases is forcibly replaced with the approximate concentration y, the following equation (9) is obtained.

[0181] [Mathematical Expression 9]

[0182]

[0183] As a result, with respect to the variable Hs, equation (9) can be calculated using the OPT-SONIC operation of equation (7), and with respect to the variable y, equation (9) can be calculated using the OPT-SONIC operation of equation (8). That is, it becomes the hypothetical base heat (hypothetical base heat H') calculated using the OPT-SONIC operation. HC The formula (9) is used for calculation. This formula (9) is based on the above... Figures 1 to 5 The explanation includes the "hypothetical basal heat calculation formula". This hypothetical basal heat H' HC The basic calorific value H of natural gas can be used to determine the concentration of impurity components separately and calculated using equation (6). HC The substitute value (approximate value).

[0184] Furthermore, for the calculation formula of the normalized compressibility coefficient N based on equation (5), if the basic heat H is replaced... HC The hypothetical basic heat H' is replaced by the above equation (9). HCAnd by applying a micro-correction, it can be transformed into the following equation (10). That is, equation (10) also becomes the same normalized compressibility coefficient calculation formula as equation (5). As all of the above have been stated, the hypothetical basic heat H' HC It can be calculated using OPT-SONIC calculations, therefore even the concentration of impurity components (nitrogen concentration x) N2 Carbon dioxide gas concentration x CO2 Even if the formula is not clear, the normalized compression coefficient of equation (10) can still be calculated.

[0185] [Mathematical Expression 10]

[0186]

[0187] in,

[0188]

[0189]

[0190] Here,

[0191] a N2 =0.000139157, b N2 =0.00972504, c N2 =0.189587

[0192] N' in equations (10) and (10.1) HC It is the hypothetical basic heat H' of natural gas without (removed) impurity components. HC The corresponding hypothetical normalized compressibility coefficient of natural gas that does not contain (removed) impurity components. That is, it is the operationally normalized compressibility coefficient, i.e., the hypothetical normalized compressibility coefficient, assuming that the natural gas (without impurities) consists only of alkanes and that its basal heat is a hypothetical basal heat H.

[0193] In addition, k' in equation (10) is relative to the hypothetical basal heat H' HC The corresponding hypothetical normalized compressibility factor is a factor that corrects for the changes caused by nitrogen and carbon dioxide gases, which are impurities in natural gas (the overall effect of nitrogen and carbon dioxide gases as impurities). It is referred to below as the "impurity correction factor".

[0194] Equation (10.1) is based on Equation (5.1) while keeping its coefficient constant, and using the basic heat H. HC Replaced with hypothetical basal heat H' HC The resulting formula.

[0195] On the other hand, equation (10.2) is the N2 correction coefficient k selected from equation (5.2). N2The formula for calculating the impurity gas correction factor (k') is used as a reference. That is, in order to "correct the overall effect of nitrogen and carbon dioxide gases as impurities," the factor for "correcting the effect of nitrogen as an impurity gas" (N2 correction factor k') is used. N2 Additionally, regarding basal calories, we use a hypothetical basal calorie H'. HC Specifically, the basic heat H on the right side of equation (5.2) is... HC Replaced with hypothetical basal heat H' HC And for the coefficients a of the terms on the right side of equation (5.2) N2 b N2 c N2 The impurity correction factor k' is calculated by multiplying each factor by a predetermined constant (0.85 in this case). This predetermined constant (0.85) is a value that can be set (adjusted) based on the type of the target gas (natural gas) (assuming the concentration of carbon dioxide gas contained in the gas as an impurity), and is hereinafter referred to as the "adjustment factor D". The adjustment factor D will be described in detail later.

[0196] That is, in equation (10), the total concentration of impurities y is used instead of the nitrogen concentration x as the change (quantity) caused by the presence of impurity components. N2 and carbon dioxide gas concentration x CO2 The value (measured value), in addition, is determined based on the N2 correction coefficient k. N2 The calculated impurity gas correction factor k' corrects for the variation (deviation) caused by using the approximate total concentration y of impurities.

[0197] Thus, according to equation (10), the heat H can be calculated based on the refractive index of natural gas (refractive index converted to heat H). OPT ) and density (density converted to heat H) SONIC These two parameters are used to calculate the normalized compressibility coefficient N, which is unaffected by pressure P and temperature T.

[0198] Based on this investigation, and referring to the above... Figure 4 In the normalized compressibility coefficient calculation method described in (B), the refractive index and density of natural gas are used as input parameters, and the normalized compressibility coefficient N is calculated using the above equation (10). By introducing the concept of normalized compressibility coefficient N, it is possible to calculate the compressibility coefficient by arbitrarily changing only the pressure P and temperature T, based on the general formula for calculating the compressibility coefficient. Furthermore, compared with the normalized compressibility coefficient calculation method using equation (5), the number of input parameters can be reduced.

[0199] This is based on the fact that, for the same type of natural gas under the same conditions (pressure, temperature, etc.), the normalized compressibility coefficient N based on equation (5) and the normalized compressibility coefficient N based on equation (10) are approximately the same value. This will be explained below.

[0200] Equation (5) calculates the basic heat H based on natural gas. HC Normalized compression factor N HC This will be compared with the separately measured nitrogen concentration x. N2 and carbon dioxide gas concentration x CO2 The corresponding correction terms are added together to correct for errors caused by impurities, and the normalized compressibility coefficient N(x) is calculated taking into account the impurities. N2 x CO2 Specifically, regarding nitrogen concentration x N2 Multiply by the N2 correction factor k N2 Regarding the concentration of carbon dioxide gas x CO2 Multiply by CO2 correction factor k CO2 And add these correction terms together.

[0201] On the other hand, equation (10) refers to the normalized compression coefficient in operation, that is, the hypothetical normalized compression coefficient N'. HC The error caused by the composition of the impurities is corrected by adding a correction term obtained by multiplying the approximate concentration y of the total impurities by the impurity correction factor k'. The normalized compressibility factor N, which takes into account the composition of the impurities, is calculated.

[0202] Here, we focus on the N2 correction coefficient k N2 CO2 correction factor k CO2 And the correction factor k' for impurities. Considering the actual presence of natural gas, its basic calorific value can be assumed to be 39.933–47 MJ / m³. 3 (Even at its highest, it's only 55 MJ / m 3 (Approximately). The applicant of this application has a basic heat capacity H within this range. HC The N2 correction coefficient k in Chinese formula (5.2) N2 and the CO2 correction coefficient k in equation (5.3) CO2 The possible values ​​for were investigated. The results are presented below. Figure 8 .exist Figure 8 In the middle, the horizontal axis represents the basic heat H. HC The vertical axis represents the correction factor k. N2 k CO2 .

[0203] Based on this result, within the aforementioned range of basic heat, the N2 correction factor k N2 If the value is positive, the CO2 correction coefficient k CO2 It is a negative value. This means that if the nitrogen concentration x N2If the normalized compression factor N(x) increases, then... N2 x CO2 If the carbon dioxide concentration x increases, CO2 If the normalized compression factor N(x) increases, then... N2 x CO2 (It becomes smaller.)

[0204] On the other hand, since the impurity correction coefficient k' in equation (10) is the N2 correction coefficient k in equation (5.2), N2 The value is obtained as a reference and is therefore usually positive. That is, (k'×x) in equation (10) N2 ) terms and (1.56k'×x CO2 Since all terms are positive, the impurity gas correction coefficient k' in equation (10) cannot be compared with the CO2 correction coefficient k. CO2 That way, at a carbon dioxide gas concentration of x CO2 In the case of increasing it, it has the effect of reducing the normalized compression factor N (a negative effect).

[0205] However, at carbon dioxide gas concentration x CO2 When it is 0 mol%, the approximate total concentration y of the impurities is different from the nitrogen concentration x. N2 Completely identical, therefore containing (excluding) the hypothetical basic heat H' of impurities. HC Becoming the basic heat H of equation (6) HC The result is the same, the hypothetical basal heat H' HC It is derived by using the original equation (9), based on the calorific value (total calorific value) Hs of natural gas obtained from the OPT-SONIC calculation, and by inversely calculating the approximate total concentration y of the mixed gases. However, when the carbon dioxide concentration x... CO2 When the concentration is greater than 0 mol%, the concentration of carbon dioxide gas x is present in the approximate concentration y of the total mixed gas used in the inverse operation. CO2 It is 1.56 times, therefore the hypothetical basal heat H' HC Having this carbon dioxide gas concentration x CO2 The more it increases, the closer it gets to being greater than the basal heat H. HC The property of directional offset. Based on Figure 7 It can be seen that if the basal heat H HC If the normalized compression factor N increases, then the normalized compression factor N decreases. Therefore, the hypothetical normalized compression factor N' in equation (10.1) corresponding to the first term of equation (10) is... HC The normalized compression coefficient N of equation (5.1) corresponding to the first term of equation (5) is compared with that of equation (5). HC Small.

[0206] On the other hand, for the approximate total concentration y of the mixed gases used in the second term of equation (10), the concentration x of the carbon dioxide gas present therein is...CO2 It is 1.56 times the actual value. Meanwhile, the coefficient k' used in the second term, as in equation (10.2), includes the hypothetical basic heat H' in both the first and second terms. HC That is, as mentioned above, due to the hypothetical basal heat H' HC Having carbon dioxide gas concentration x CO2 The more it increases, the closer it gets to being greater than the basal heat H. HC Due to the directional shift property, in the case of carbon dioxide gas, the k'×y of the second term of equation (10) is larger than the sum of the second and third terms of equation (5).

[0207] That is, when comparing equations (5) and (10) as a whole, the first term of equation (10) is smaller than the first term of equation (5). On the other hand, the k'×y of the second term of equation (10) is larger than the sum of the second and third terms of equation (5). In equation (10), since the increase in the first term and the decrease in the second term cancel each other out, it is expected that the calculation result will be close to (not significantly deviating from) that of equation (5). That is, it is believed that by appropriately adjusting (the cancellation of these values) the first and second terms of equation (10), it is possible to obtain the result at a carbon dioxide gas concentration x. CO2 Increasing the value can reduce the hypothetical normalized compression factor N'. HC The effect (negative effect) of the impurity correction coefficient k'. Therefore, the adjustment coefficient D (for the coefficients a of the terms on the right side of equation (5.2) in equation (10.2) was studied. N2 b N2 c N2 Multiply by the adjustment factor D), and by appropriately selecting the adjustment factor D, the error of the calculation results based on equations (5) and (10) can be reduced.

[0208] The applicant of this application conducted a simulation comparing the compressibility coefficient calculated using ISO 12213-3 with the normalized compressibility coefficient N calculated using OPT-SONIC (Equation (10)) and based on the normalized compressibility coefficient N for natural gas with various compositions of carbon dioxide and nitrogen.

[0209] As a result, the following value (e.g., 0.85) is chosen as the adjustment factor D for equation (10.2), which is a value that can minimize the error between the compressibility factor calculated using ISO 12213-3 and natural gas with high carbon dioxide and nitrogen content.

[0210] The adjustment factor D is 0.85 in the example above, but it is not limited to this and an appropriate value can be selected according to the type of natural gas. For example, in the case of natural gas that does not contain carbon dioxide, such as LNG vaporization gas, the adjustment factor D is preferably set to 1.0 (or a value close to it). In the case of natural gas with adjustment factor D = 1, i.e., natural gas that does not contain carbon dioxide, the impurity gas correction factor k' and the N2 correction factor k N2 Equal, hypothetical basal heat H' HC The basic heat H of equation (6) HC Equal. Furthermore, in the case of adding biogas to natural gas, the effect of carbon dioxide concentration may be dominant; therefore, it is preferable to set the adjustment factor D to a low value (e.g., around 0.7). In this embodiment, the adjustment factor D is, for example, a value of 0.5 ≤ D ≤ 1.5.

[0211] Thus, based on the computing device and method of this embodiment, the hypothetical basal heat H' can be calculated using OPT-SONIC calculation. HC and use it as the basic heat H HC The substitute is used to calculate physical quantities related to the state of natural gas (e.g., compressibility factor). Additionally, in this case, a miscellaneous gas correction factor k' can be calculated, which is based on the carbon dioxide gas concentration x. CO2 The increase (through appropriate cancellation of the first and second terms of equation (10)) can achieve the effect of making the hypothetical normalized compression coefficient N' of the first term of equation (10) more uniform. HC The effect of decreasing (acting as a negative effect). By using the adjustment factor D in the calculation of the impurity gas correction factor k', it is possible to adjust the carbon dioxide gas concentration x according to the actual situation. CO2 The degree of cancellation between the first and second terms of equation (10) is adjusted by increasing the value of D, thereby enabling the adjustment coefficient D to be set and adjusted to a suitable value (0.85 in this case). For example, in the computing device 1 of this embodiment, the adjustment coefficient D can be kept at a preset value (e.g., an initial value), or it can be set to allow arbitrary adjustment coefficient D to be input from the outside. In addition, in the program of this embodiment, the adjustment coefficient D can be kept at a preset value (constant, initial value), or the adjustment coefficient D can be used as one of the input parameters.

[0212] Therefore, for the same type of natural gas under the same conditions, the normalized compressibility coefficient N(x) calculated by equation (5) is the same. N2 x CO2 Both the normalized compression coefficient N calculated by equation (10) and the normalized compression coefficient N can obtain the same value.

[0213] <Generalization from normalized compression coefficients>

[0214] The normalized compression coefficient N(x) obtained using equation (5) N2 x CO2 Alternatively, if the normalized compressibility coefficient N obtained by equation (10) is converted into the general formula Z(T, P) of the compressibility coefficient Z for pressure P and temperature T, the following conversion formula (11) is used.

[0215] [Mathematical Expression 11]

[0216]

[0217] in,

[0218]

[0219]

[0220] It should be noted that the a included in equations (11.1) and (11.2) m，n b m，n The coefficient is determined by the heat of gases A and B selected during the normalization of the compressibility coefficient. In this embodiment, it is for 39.933 MJ / m³. 3 Gas A (CH4 = 100%) and 46.547 MJ / m 3 (CH4:C2H6:C3H8:C4H 10 The coefficient of gas B is 86:8:4:2. In this case, the coefficient a m，n The values ​​shown in Table 1 below, b m , n The values ​​are shown in Table 2 below.

[0221] [Table 1]

[0222] a m，n

[0223]

[0224] [Table 2]

[0225] b m，n

[0226]

[0227] It should be noted that in this embodiment, the heat H is for gas A. HC It is 39.933 MJ / m 3 Gas B (pure methane, CH4 = 100%) is a heat source (H). HC It is 46.547 MJ / m 3 The gas (CH4:C2H6:C3H8:C4H) 10The case of a gas with a composition of 86:8:4:2 was described. However, it is not limited to this; gases A and B can each be any gas available on-site, for example, any gas available in the field. In this case, the coefficient a... m，n b m，n It becomes a predetermined value corresponding to the gas used.

[0228] The calculation result of equation (5) or equation (10), or the normalized compression coefficient calculation unit 151 of the calculation device 1 in this embodiment (refer to...) Figure 2 The output of (B) is set as the normalized compression coefficient N(x) of the first term (dashed border) on the right side of equation (11). N2 x CO2 The value of ) can be used as the normalized compressibility coefficient N based on equation (10). Then, by substituting any temperature T and pressure P into equation (11), the compressibility coefficient Z of natural gas under the conditions of temperature T and pressure P can be obtained.

[0229] Figure 9 The compression factor is calculated using the conventional calculation method based on ISO 12213-3, and the normalized compression factor N(x) is calculated using equation (5) in this embodiment. N2 x CO2 The graph compares the compressibility coefficient Z obtained by equation (11) with the compressibility coefficient N obtained by equation (11) calculated using equation (10). The horizontal axis is the compressibility coefficient Z obtained using the calculation method based on ISO 12213-3, and the vertical axis is the normalized compressibility coefficient N(x) calculated using equation (5) in this embodiment. N2 x CO2 The compressibility coefficient Z obtained by equation (11) and the normalized compressibility coefficient N calculated by equation (10) are obtained by equation (11). Additionally, the pressure (P) condition is 0.101325 MPa. Figure 9 ), 2MPa Figure 10 ), 5MPa Figure 11 ), 7MPa Figure 12 ), 10MPa Figure 13 ), 12MPa Figure 14 Under various pressure (P) conditions, the temperature (T) conditions are calculated in three cases: -20℃, 20℃, and 40℃.

[0230] Therefore, even under different pressure P and temperature T conditions, the error between the calculated results and the compressibility coefficient based on ISO12213-3 converges to ±0.05% to ±2.0%, showing a high degree of consistency.

[0231] Thus, according to this embodiment, compared with the conventional method (the calculation method based on ISO12213-2 and ISO12213-3), by introducing the concept of normalized compressibility factor N, the compressibility factor of natural gas can be calculated simply and easily.

[0232] In addition, the hypothetical basal heat H' is calculated specifically by using the OPT-SONIC operation. HC This allows for the calculation of physical properties related to the combustion or state of natural gas. In particular, it enables the calculation of the basic calorific value H of natural gas. HC In the calculation of various physical properties (e.g., compressibility coefficient), the hypothetical basal heat H' can be used. HC In the example above, for those who can use the basic heat H HC Regarding the calculated compressibility coefficient Z, the hypothetical basal heat H' can be utilized. HC This reduces the number of input parameters required for calculations. Since the input parameters are not only fewer in number, but also readily available values ​​such as the refractive index and density of natural gas (the equipment used to obtain these values ​​is small, simple, inexpensive, and easy to handle), physical properties (such as compressibility) can be calculated more simply and easily compared to conventional methods that use analytical values, such as those obtained using gas chromatography.

[0233] In addition, the basic heat H can be used HC The calculated physical properties are not limited to the compression coefficient; for example, even the combustion rate can be calculated in the same way. This will be explained below.

[0234] <Methods for Calculating Combustion Rate>

[0235] The applicant of this application verified how the composition of various natural gas species affects the basal heat and combustion rate (MCP). The natural gas used in the verification was a mixture of gases consisting only of three different alkane hydrocarbon gases ((CH4-C2H6), (CH4-C3H8), and (CH4-C4H). 10 )gas).

[0236] Figure 15 (A) is a graph showing the relationship between the basal heat of the three gas mixtures (calculated based on ISO 6976) and the values ​​of the combustion rate MCP calculated using gas chromatography analysis based on conventional methods (Equation (Pa)). The horizontal axis represents the basal heat [MJ / m³]. 3 The vertical axis represents the combustion rate (MCP). As a result, the correlation between basal heat and MCP can vary considerably depending on the composition of the natural gas (mixture).

[0237] However, the same verification was performed on actual natural gas (natural gas with the composition described in ISO TR22302 2014 Table B.6 No.1-24), and the result was that the basal heat H HC The relationship between the combustion rate MCP and the combustion rate is close to that of (CH4-C3H8) gas. Based on this result, it is found that the combustion rate MCP of actual natural gas is approximately represented by the following equation (12).

[0238] [Mathematical Expression 12]

[0239]

[0240] In addition, regarding Figure 15 The (CH4-C3H8) gas shown in (A) was mixed with 5 mol% nitrogen and 5 mol% carbon dioxide as impurities, verifying the relationship between the change in combustion rate and the basal heat with (CH4-C3H8) gas as the baseline (0). The results are shown in Figure 15 (B). The results show that the change in combustion rate caused by the mixing of impurity components increases with the increase of basal heat.

[0241] Based on this result, it was found that the curve of the reference gas (CH4-C3H8) without impurity components (CH4-C3H8) was... Figure 15 In the natural gas (actually existing natural gas) near (A) with basic heat, x N2 [mol%] of nitrogen, x CO2 When [mol%] carbon dioxide gas is mixed together as a mixed gas component, the combustion rate is represented by equation (13).

[0242] [Mathematical Expression 13]

[0243]

[0244] in,

[0245] A = 0.00265438 × H HC -0.30474328 (13.1)

[0246] B = 0.0062857 × H HC -072340434 (13.2)

[0247] It should be noted that the heat H used in equation (13) HC This represents the basic calorific value of natural gas. Here, natural gas contains nitrogen (nitrogen concentration x). N2 [mol%]) and carbon dioxide gas (carbon dioxide gas concentration x) CO2When [mol%]) is used as a mixed gas component, the total calorific value Hs and the basic calorific value H of the natural gas are expressed by the following equation (14). HC The relationship between them.

[0248] [Mathematical Expression 14]

[0249]

[0250] That is, equation (13) is based on the heat Hs of natural gas and the carbon dioxide concentration x. CO2 Nitrogen concentration x N2 These three parameters are used to calculate the combustion rate using equation (14). That is, for natural gas containing impurities, it can be said that as long as the heat (total heat) Hs and carbon dioxide concentration x of the natural gas can be obtained... CO2 Nitrogen concentration x N2 Then the basic heat H can be calculated using equation (14). HC The combustion rate MCP of the natural gas is calculated using equation (13).

[0251] Based on this investigation, and referring to the above... Figure 5 In the combustion rate calculation method described in (A), the calorific value of natural gas (total calorific value) Hs and the carbon dioxide concentration x are used. CO2 Nitrogen concentration x N2 These three elements are used as input parameters. Equations (13) and (14) above are used as formulas for calculating combustion rate, and the combustion rate MCP is calculated.

[0252] Equations (13) (and (14)) are based on the calorific value Hs of natural gas and the molar concentration of carbon dioxide x. CO2 Nitrogen molar concentration x N2 These three parameters are used to calculate the combustion rate (combustion rate calculation formula).

[0253] <Optical-Acoustic Combustion Speed ​​Algorithm>

[0254] Furthermore, in the calculation of combustion rate, the OPT-SONIC operation can be used in exactly the same way as in the calculation of compression ratio, thus reducing the number of input parameters. Additionally, the hypothetical basal heat H' can be calculated in exactly the same way as in the calculation of compression ratio. HC (Equations (7) to (9) above).

[0255] Moreover, by using the hypothetical basal heat H' HC The basic heat H is used as a substitute for equation (13) HC Therefore, even if the concentration of impurity components (nitrogen concentration x) N2 carbon dioxide gas concentration x CO2If the value is unclear, the calculation corresponding to the combustion rate calculation based on equation (13) is performed using the following equation (15). That is, equation (15) is also the combustion rate calculation equation.

[0256]

Number 15

[0257] [Mathematical Expression 15]

[0258]

[0259] in,

[0260] C=1.1×A=1.1×(0.00265438×H′ HC -0.30474328) (15.1)

[0261] Here, if we compare equations (13) and (15), then in equation (13), the fourth term on the right (A×x) N2 ) and the 5th item (B×x) CO2 ) are added as correction terms based on the inclusion of impurity components. On the other hand, in equation (15), the fourth term on the right (C×(x)) is added. N2 +1.56×x CO2 This is added as a correction term based on the inclusion of impurity components. If referenced again... Figure 15 In the calculation of combustion rate based on equation (13), regardless of nitrogen concentration x (B), N2 Carbon dioxide gas concentration x CO2 An increase in any of these factors tends to decrease the change in combustion rate, but an increase in carbon dioxide concentration x... CO2 The effect on the change in combustion rate can be considered as nitrogen concentration x N2 Roughly twice as much.

[0262] Furthermore, in equation (15) using the OPT-SONIC operation, according to the fourth term on the right, the carbon dioxide gas concentration x CO2 The effect of the change in combustion rate is the nitrogen concentration x N2 The effect on the change in combustion rate is 1.56 times. That is, in equations (13) and (15), although there are some cases, it is believed that by making corrections based on the calculation of equation (15), it is possible to obtain values ​​that are approximately the same as those calculated by equation (13).

[0263] Therefore, in this embodiment, the C included in the correction term of Equation (15) is set to 1.1 times the A included in the correction term of Equation (13.1) in such a way that the calculation results of the combustion rate based on Equation (13) and Equation (15) are approximately the same (refer to Equation (15.1)).

[0264] For the value multiplied by A in Equation (15.1) (referred to as the "adjustment factor F"), simulations were performed comparing the conventional method of calculating the combustion rate (based on Equation (Pa)) with the method of calculating the combustion rate using OPT-SONIC calculation (based on Equation (15)) for natural gas with various gas compositions. As a result, the adjustment factor F in Equation (15.1) was selected as a value that minimizes the error between the combustion rate calculated according to Equation (Pa) for both natural gas with high carbon dioxide and natural gas with high nitrogen content.

[0265] The adjustment factor F is 1.1 in the example above (F = 1.1), but it is not limited to this and should be set to an appropriate value depending on the type of natural gas (e.g., 0.5 ≤ F ≤ 1.5).

[0266] Thus, based on the computing device and method of this embodiment, the hypothetical basal heat H' can be calculated using OPT-SONIC calculation. HC By using this hypothetical basal heat H' HC And an adjustment factor F is used to calculate physical quantities related to the combustion of natural gas (such as combustion rate) as the basic heat H. HC The substitution is used. Furthermore, in this case, the configuration is such that the adjustment coefficient F can be set and adjusted to an appropriate value (here, 1.1). For example, in the computing device 1 of this embodiment, the adjustment coefficient F can be kept at a preset value (e.g., an initial value), or it can be configured to allow arbitrary adjustment coefficient F to be input from an external source. Additionally, in the program of this embodiment, the adjustment coefficient F can be kept at a preset value (constant, initial value), or it can be used as one of the input parameters.

[0267] Therefore, regardless of the combustion rate MCP(x) calculated by equation (13) N2 x CO2 Whether it is the combustion rate MCP calculated by formula (15), the same value can be obtained as long as it is the same type of natural gas under the same conditions.

[0268] Figure 16 A graph is shown comparing the combustion rate obtained according to the previous formula (Pa) with the combustion rate calculated by formulas (13) and (15). Figure 16 The horizontal axis of (A) is the combustion rate MCP calculated according to equation (Pa), and the vertical axis is the combustion rate MCP(x) calculated according to equation (13). N2 x CO2 ). Figure 16The horizontal axis of (B) is the combustion rate MCP calculated according to formula (Pa), and the vertical axis is the combustion rate MCP calculated according to formula (15). The calculated result is consistent with the combustion rate calculated using the existing formula (Pa) with high precision.

[0269] As explained above, in this embodiment, when calculating the physical properties related to natural gas that does not contain hydrogen, carbon monoxide, or whose content is negligible, the hypothetical basal heat H' is calculated using the OPT-SONIC calculation. HC This allows for easy calculation of the basic heat H. HC Multiple different physical property values ​​(e.g., compression ratio, combustion rate, etc.) are calculated. For example, the compression ratio is usually calculated using methods based on ISO 12213-2, ISO 12213-3, etc., and the combustion rate is calculated using the method shown in equation (Pa). The types and number of these input parameters are also set separately, and input parameters need to be obtained (prepared) for each physical property value. That is, depending on the input parameters, measuring devices, analytical devices, etc., are required, which is inconvenient.

[0270] According to this embodiment, even with different physical property values, the hypothetical basic heat H' is calculated. HC Up to this stage (step), general-purpose computing devices and methods can be used. In particular, the input parameters are the refractive index and density of natural gas, and the devices used to obtain them are smaller, simpler, and cheaper than gas chromatographs. Even when calculating multiple different physical property values, the hypothetical basal heat H' can be used up to calculate the intermediate value. HC It can also utilize common devices and methods, thus offering high convenience and enabling simple and easy calculations.

[0271] Furthermore, in this embodiment, the calculation of the compressibility coefficient related to natural gas that does not contain hydrogen, carbon monoxide, or whose content is negligible, is based on the calorific value Hs of the natural gas (total calorific value MJ / m³). 3 The total calorific value is MJ / m³ 3 The value is obtained by conversion under the conditions of 0℃ as the measurement reference temperature, 0℃ as the combustion reference temperature, and 101.325kPa; the carbon dioxide gas concentration x CO2 Nitrogen concentration x N2 These three input parameters are used to calculate the normalized compressibility factor N. Then, based on the normalized compressibility factor N and the general formula for compressibility factor (Z(T,P)) with pressure P and temperature T as parameters, the compressibility factor Z under the required pressure P and temperature T is calculated.

[0272] Therefore, compared to previous calculation methods based on ISO 12213-2 and ISO 12213-3, the number of input parameters can be significantly reduced. Furthermore, in the calculation methods based on ISO 12213-2 and ISO 12213-3, pressure P and temperature T become the initial input data. When calculating the compressibility coefficient under different temperature and pressure conditions, it is necessary to recalculate based on all the input data required in each calculation method, which lacks convenience. Additionally, when temperature and pressure cannot be measured, there is also the problem of not being able to obtain the numerical values ​​related to the compressibility coefficient.

[0273] According to this embodiment, the normalized compressibility factor N is calculated, and based on the normalized compressibility factor N, it is converted into a general formula (function Z(T, P)) for calculating the compressibility factor. Therefore, when calculating the compressibility factor Z under different temperature and pressure conditions, various compressibility factors Z can be calculated simply by changing the input parameters of temperature T and pressure P in the general formula (function Z(T, P)).

[0274] Furthermore, by using the OPT-SONIC calculation to calculate the normalized compressibility factor N, the input parameters can be reduced to just the refractive index and density of natural gas. In addition, both refractive index and density measurements can be performed using simpler, smaller, and cheaper equipment compared to conventional gas chromatographs, making operation easier.

[0275] Furthermore, in this embodiment, the calculation of the combustion rate related to natural gas containing only trace amounts of natural gas that does not contain hydrogen or carbon monoxide, or whose content is negligible, can be based on the calorific value Hs of the natural gas (total calorific value MJ / m³). 3 The total calorific value is MJ / m³ 3 The value is obtained by conversion under the conditions of 0℃ as the measurement reference temperature, 0℃ as the combustion reference temperature, and 101.325kPa; the carbon dioxide gas concentration x CO2 Nitrogen concentration x N2 These three input parameters are used for calculation.

[0276] Therefore, compared with the previous calculation method of formula (Pa), the number of input parameters can be significantly reduced.

[0277] Furthermore, by using OPT-SONIC calculations to determine the combustion rate, the input parameters can be reduced to just the refractive index and density of natural gas. In addition, both refractive index and density measurements can be performed using simpler, smaller, and cheaper devices compared to conventional gas chromatographs, making operation easier.

[0278] This invention is not limited to the above-described embodiments, and various modifications can be made without departing from its spirit and technical concept.

[0279] For example, in the above embodiment, an example of calculating heat Hs using the conversion heat calculation formula (OPT-SONIC formula) shown in equation (7) is shown, but heat Hs can also be obtained by other known methods (calculations).

[0280] Furthermore, in the above embodiments, an example is provided where the OPT-SONIC formula is used without measuring the impurity gas concentration (nitrogen concentration x). N2 and carbon dioxide gas concentration x CO2 However, it is also possible to obtain (measure, etc.) at least one of the impurities to perform the above-mentioned calculations.

[0281] Alternatively, the target gas can be, for example, liquefied natural gas (LNG) vaporized gas, biogas, etc. Furthermore, the physical property values ​​can be "smoke dust coefficient," "incomplete combustion index," etc. Also, the mixed gas is not limited to nitrogen or carbon dioxide; as long as the type is specified, the same implementation can be achieved, yielding the same results.

Claims

1. A computing device, characterized in that, Calculate the values ​​associated with the flammability of the target gas containing impurities. The computing device has: The heat calculation unit calculates heat H based on the refractive index obtained from the refractive index of the target gas. OPT and the density-converted heat H obtained based on the density of the target gas. SONIC The heat Hs of the object gas is calculated according to the condition satisfying Equation 7 below. Equation 7 α: Correction coefficient; The unit for calculating the approximate concentration of impurity gases calculates the heat H based on the refractive index. OPT And the density converted to heat H SONIC The approximate concentration y of the total amount of the impurity gas components is calculated according to the condition satisfying Equation 8 below. ...Formula 8, ， x N2 : Nitrogen concentration in the target gas x CO2 The concentration of carbon dioxide in the target gas; and The hypothetical basic heat calculation unit calculates the basic heat of the target gas, i.e., the hypothetical basic heat H', based on the heat Hs and the approximate concentration y, according to the condition satisfying Equation 9. HC , ...Form 9.

2. The computing device according to claim 1, characterized in that, The target gas is natural gas. The main components of the impurity gas are nitrogen and carbon dioxide.

3. The computing device according to claim 1, characterized in that, The computing device includes a property value calculation unit, which utilizes the hypothetical basic heat H' HC To calculate the physical properties of the object gas.

4. The computing device according to claim 2, characterized in that, The computing device includes a property value calculation unit, which utilizes the hypothetical basic heat H' HC To calculate the physical properties of the object gas.

5. The computing device according to claim 3, characterized in that, The property value calculation unit performs error correction corresponding to the impurity gas components.

6. The computing device according to claim 4, characterized in that, The property value calculation unit performs error correction corresponding to the impurity gas components.

7. The computing device according to any one of claims 3 to 6, characterized in that, The physical property value mentioned is the compressibility factor.

8. The computing device according to claim 7, characterized in that, The compression coefficient is calculated based on the normalized compression coefficient.

9. The computing device according to any one of claims 3 to 6, characterized in that, The physical property value mentioned is the combustion rate.

10. A calculation method, characterized in that, It is a calculation method for determining the values ​​associated with the flammability of a target gas containing impurities. The calculation method includes: Obtain the heat H calculated from the refractive index of the target gas. OPT And the density-converted heat H obtained based on the density of the target gas. SONIC Steps; Based on the refractive index, the heat H is calculated. OPT And the density converted to heat H SONIC The steps for calculating the heat Hs of the target gas according to the condition satisfying Equation 7 are as follows: ...Formula 7, α: Correction coefficient; Based on the refractive index, the heat H is calculated. OPT And the density converted to heat H SONIC The steps involve calculating the approximate total concentration of the impurity gas components, i.e., the approximate total concentration y of the impurity gas, according to the condition satisfying Equation 8 below. ...Formula 8, ， x N2 : Nitrogen concentration in the target gas x CO2 The concentration of carbon dioxide in the target gas; and Based on the heat Hs and the approximate total concentration y of the impurity gas, the base heat, i.e., the hypothetical base heat H', of the target gas assuming the removal of the impurity gas components is satisfied, is calculated according to the following equation 9. HC Steps, ...Form 9.

11. The calculation method according to claim 10, characterized in that, The target gas is natural gas. The main components of the impurity gas are nitrogen and carbon dioxide.

12. The calculation method according to claim 10, characterized in that, The calculation method includes the step of using the hypothetical basal heat to calculate the physical property values ​​of the target gas.

13. The calculation method according to claim 11, characterized in that, The calculation method includes the step of using the hypothetical basal heat to calculate the physical property values ​​of the target gas.

14. The calculation method according to claim 12, characterized in that, When calculating the aforementioned physical property values, error corrections are performed corresponding to the impurity gas composition.

15. The calculation method according to claim 13, characterized in that, When calculating the aforementioned physical property values, error corrections are performed corresponding to the impurity gas composition.

16. The calculation method according to any one of claims 12 to 15, characterized in that, The physical property value mentioned is the compressibility factor.

17. The calculation method according to claim 16, characterized in that, The compression coefficient is calculated based on the normalized compression coefficient.

18. The calculation method according to any one of claims 12 to 15, characterized in that, The physical property value mentioned is the combustion rate.

19. A storage medium, characterized in that, The storage medium stores a program that enables a computer to perform the computation method according to any one of claims 10 to 18.

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