JP3339669B2 - Monitoring method for mixed gas in city gas feedstock using thermal conductivity calorimeter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates is applied to mixing facilities of city _{gas, CO 2, N 2, O} 2 , etc. incombustible thermal conductivity type heat contamination of miscellaneous gas to natural gas raw material It relates to a method of monitoring using a meter.

[0002]

2. Description of the Related Art FIG. 9 conceptually shows a conventional gas mixing system using natural gas from a plurality of gas wells as a raw material for city gas. Natural gas is supplied to each source gas line 1a, 1b,
The gas is supplied to the gas mixing equipment 2 through 1c, mixed at an appropriate raw material ratio by the control instrument 3, and then sent out via the transport conduit 4 or the like.

At this time, each raw material gas line 1a, 1b, 1
The components of natural gas from each well flowing through the well c are monitored by a gas chromatograph 5, and natural gas in any of the wells
When a gas such as O ₂ , N ₂ , O ₂ is mixed and the gas chromatograph 5 detects the mixing, the controller 3 is controlled to control the gas through the raw material gas lines 1a, 1b, 1c. By performing control to reduce or cut off the mixing ratio of the gas supplied to the mixing equipment 2, control to reduce the concentration of miscellaneous gas in the raw material gas transported through the transport conduit 4 is performed.

[0004]

Although the gas chromatograph can reliably detect the components of the above-mentioned miscellaneous gases, the time required for the detection is as long as several minutes to several tens of minutes. The gas may pass through the mixing facility and be delivered to the transport conduit. In view of the above, an object of the present invention is to solve such a problem by making it possible to detect a miscellaneous gas in a short time by using a thermal conductivity calorimeter capable of measuring a calorific value of a raw material gas at high speed. It is assumed that.

[0005]

In order to solve the above-mentioned problems, the present invention measures the thermal conductivity of a gas at a predetermined temperature, and calculates the thermal conductivity and the calorific value from an output signal corresponding to the thermal conductivity. In a method of installing a thermal conductivity calorimeter that measures and calculates the calorific value according to the correspondence relationship in the source gas line leading to the city gas mixing facility, and monitors the mixing of miscellaneous gases into the source gas by changing the calorific value Raw material for measuring thermal conductivity
Perform at two high and low temperatures of the gas to reach the temperature on the specified side.
The calorific value is calculated from the output signal of the
Compensation for the output signal difference between high and low temperature
In addition, mixing of miscellaneous gases is
Into city gas feedstock using thermal conductivity calorimeter
We propose a monitoring method for mixed gas.

In the present invention, the correction of the heat value is performed by:
The coefficient obtained by multiplying the constant of the rate of change of the output signal difference between the high and low 2 temperatures during measurement with the constant for the output signal difference between the high and low 2 temperatures in the measurement at the time of calibration for the source gas for which the true calorific value is known is the thermal conductivity and heat generation. It is proposed that a value obtained by multiplying the calorific value calculated based on the relationship with the amount be added to the calculated calorific value as a correction value of the calorific value. This constant can be obtained by substituting each output signal and the true calorific value in the measurement at the time of calibration for the source gas whose calorific value is known, into a correction formula.

Further, in the present invention, in the above method, the thermal conductivity calorimeter may be configured such that two units, one for setting the measurement temperature of the sensor unit high and one for setting the measurement temperature low, are arranged in parallel or in parallel with the flow of the raw material gas. It is proposed to configure in series to measure the thermal conductivity at two high and low temperatures.

According to the present invention, in the above method, the thermal conductivity calorimeter includes both a sensor section for setting a high measurement temperature and a sensor section for setting a low measurement temperature in series or in series with the gas flow. It is proposed to configure in parallel to measure the thermal conductivity at two high and low temperatures.

Further, the present invention proposes that the thermal conductivity calorimeter makes the measurement temperature of the sensor section variable, and measures the thermal conductivity at two high and low temperatures by switching the measurement temperature at predetermined time intervals.

Further, the present invention proposes that the thermal conductivity calorimeter has a configuration in which the measurement temperature of the sensor section is continuously variable and the thermal conductivity is measured at a desired temperature.

According to the above arrangement, the change in the calorific value of the raw material gas due to the mixing of the miscellaneous gas can be detected at a high speed by the thermal conductivity calorimeter. It can be detected at high speed.

If the miscellaneous gas is a nonflammable gas having the same thermal conductivity as the combustible gas, a measurement error of the calorific value occurs, but the correspondence between the temperature and the thermal conductivity for each component of the city gas is as follows. Since each component is different from each other, the above-mentioned thermal conductivity is measured for two high and low temperatures, and the calorific value is calculated from the output signal at a predetermined temperature. By performing correction corresponding to the output signal difference, a heat value close to the true heat value can be obtained. Therefore, it is possible to reliably detect a decrease in the amount of heat generated due to the mixing of the miscellaneous gas, and to thereby reliably detect the mixing of the miscellaneous gas.

The correction of the calorific value is performed, for example, by changing the rate of change of the output signal difference between the high and low two temperatures during the measurement with respect to the output signal difference between the high and low two temperatures in the measurement at the time of calibration for the raw material gas whose true calorific value is known. Can be performed by adding a value obtained by multiplying a coefficient multiplied by the calorific value calculated based on the correspondence between the thermal conductivity and the calorific value as a correction value of the calorific value to the calculated calorific value.

In order to make it possible to measure the thermal conductivity at two high and low temperatures, the thermal conductivity type calorimeter is, for example, one for setting the measurement temperature of the sensor section high and one for setting the measurement temperature low.
The base is configured in parallel or series with the flow of the raw material gas, or both the sensor section for setting the measurement temperature high and the sensor section for setting the measurement temperature low are built in one and connected in series with the gas flow. Alternatively, a configuration in which the measurement temperature of the sensor unit is variable and the measurement temperature is switched at predetermined time intervals can be applied.

[0015]

Next, an embodiment of the present invention will be described. FIG. 1 shows an example in which the present invention is applied to a gas mixing system using natural gas in a plurality of gas wells as a raw material for city gas . Elements similar to those in FIG. 9 described above are denoted by the same reference numerals. Therefore, duplicate description will be omitted. In the gas mixing system of FIG. 1, instead of the gas chromatograph 5 in the conventional system, natural gas from each well is transferred by a thermal conductivity calorimeter 6a, 6b, 6c provided for each of the raw material gas lines 1a, 1b, 1c. Monitor ingredients.

Therefore, first, an example of a thermal conductivity calorimeter is described.
The principle of calorimetry will be described. FIG. 2 shows the internal structure of the thermal conductivity calorimeter.
In this configuration, a gas measurement channel 9 is formed in the inside, and a sensor unit 10 is installed in the measurement channel 9. Reference numeral 11 denotes a heat insulating material, 12 denotes a terminal box, 13 denotes a heater, and 14 denotes a manifold.

FIG. 3 is an enlarged explanatory view showing the sensor section 10. The sensor section 10 has a single crystal silicon substrate 15 and a thin film resistor 16 serving as a gas heating source and a sensor.
Is electrically insulated from the substrate 15 by the diaphragm portion 17.
And at the position of the substrate 15 which is close to the thin film resistor 16 and is thermally insulated,
8 is provided.

In such a configuration, a measuring gas is caused to flow through the measuring flow path 9, electric power is applied while controlling the thin film resistor 16 to have a constant resistance and thus a constant temperature, and the temperature sensor 18 controls the inside of the thermostat 8. While controlling the temperature to a predetermined constant temperature, the applied voltage V of the thin film resistor 16 is measured, and the average thermal conductivity λ of the measurement gas is calculated from the applied voltage V, and the calorific value H is calculated from the average thermal conductivity λ. .

The measurement principle will be described below. First, the calorific value Q _T transmitted from the thin film resistor 16 to the outside is represented by the following equation. Q _T = A · λ + B (1) where A and B are constants, the first term on the right side is the calorific value transmitted to the measurement gas, and the second term is the calorific value escaping to the silicon substrate 15. Considering that most of the power supplied to the thin film resistor 16 is changed into heat in the resistance Rh, because it is ^{_{Q T = I 2 × Rh =}} V 2 / Rh ... (2), to measure the applied voltage V of a thin film resistor The thermal conductivity λ at the average temperature of the thin film resistor 16 and the temperature sensor 18 can be calculated by the following equation. λ = V ² / (Rh × A) −B / A (3)

FIG. 4 is a plot of the applied voltage V measured for various pure gases including nonflammable gases and the value of the true thermal conductivity of each pure gas known or measured using gas chromatography or the like. The horizontal axis represents the thermal conductivity, and the vertical axis represents the square value of the voltage V applied to the thin film resistor 16 of the sensor unit 10. As shown in the figure, the correspondence between the thermal conductivity λ and the square value of the applied voltage V is approximated by a straight line, and it can be seen that the above equation (3) holds.

The calorific value H can be calculated from the thermal conductivity λ using the correspondence between the thermal conductivity λ and the calorific value H of the gas calculated as described above. At this time, it is considered that the thermal conductivity λ of the source gas and the calorific value H are in an inversely proportional relationship as in the case of the pure gas, but there is no theoretical formula between the component composition of the source gas and the thermal conductivity. Therefore, the correspondence between the thermal conductivity λ and the calorific value H of the raw material gas is appropriately determined based on a measurement in advance. For example, the range 1 of the calorific value H of city gas
0,000-12,000kcal / Nm ³ (42.0-50.4MJ / Nm ³ )
In the measurement in the range of thermal conductivity λ corresponding to 46.5 to 50.4 mW / m · K, the correspondence between the thermal conductivity λ and the calorific value H of the gas can be regarded as substantially a straight line. It can be approximated by a linear expression. H = −516.5 × λ + 33988.4… (4)

With the thermal conductivity calorimeter described above, it is possible to perform a measurement with a high response speed, for example, about several seconds. Further, since the sensor unit 10 is installed in the constant temperature bath 8, the influence of the change in the ambient temperature is small, and the thermal conductivity does not change much with the change of the pressure. No special protection or correction is required even when the device is installed near the device, and the explosion-proof structure can be easily obtained. Therefore, there are a number of advantages that it can be installed on the site with installation work equivalent to that of a normal industrial measuring instrument.

In this way, the change in the calorific value of the raw material gas can be detected at high speed by the thermal conductivity calorimeter 6, and the incombustible miscellaneous gas can be detected due to the decrease in the calorific value. If the miscellaneous gas has the same thermal conductivity as the combustible gas, such as CO ₂ or N ₂ , a measurement error of the calorific value occurs.

That is, the relationship between the thermal conductivity of the gas and the calorific value is almost inversely proportional as described above. When all the components of the raw material gas are flammable gas, the thermal conductivity increases as the calorific value increases. descend. However, if a nonflammable gas having the same thermal conductivity as the flammable gas is mixed into the raw material gas in which the composition of the flammable gas has not changed, the calorific value is reduced due to the mixing of the nonflammable gas. Nevertheless, the measured value of the calorific value may not change because the thermal conductivity does not change. That is, in this case, the measured calorific value becomes higher than the reduced true calorific value, so that the mixture of the miscellaneous gas cannot be detected.

Therefore, the present invention focuses on the fact that the correspondence between the temperature and the thermal conductivity of each component of the city gas is different for each component. For two temperatures, the calorific value is calculated from the output signal at the predetermined temperature, and the calculated calorific value is corrected according to the difference between the high and low temperature output signals to generate a calorific value close to the true calorific value. Thus, the amount of miscellaneous gas due to a decrease in the amount of generated heat can be detected at a high speed.

First, FIG. 5 to FIG. 7 schematically show an example of a calorific value measuring system of city gas to which the method of the present invention for performing the thermal conductivity of the raw material gas whose calorific value is to be measured at two high and low temperatures is applied. In these figures, reference numeral 19 represents one of the measurement lines branched from the above-mentioned raw material gas line 1 (1a, 1b, 1c). The raw material gas flowing from the raw gas line 1 to the measurement line 19 is provided for measurement of the calorific value by the thermal conductivity type calorimeter 6, and then the outside air is supplied. Or return to the source gas line.

In the system shown in FIG. 5, two units (6a, 6b) of the thermal conductivity calorimeter 6 having the above-described configuration are arranged in series with the measurement line 19. Each of these thermal conductivity calorimeters 6a and 6b is provided with a sensor section 10a and 10b, respectively. The measurement temperature on one side is set high and the set temperature on the other side is set low.

With this configuration, the sample gas flowing through the measurement line 19 is supplied to the upstream and downstream thermal conductivity calorimeters 6.
Measurement of the thermal conductivity at two high and low temperatures is performed while sequentially flowing through a and 6b.

In this system, which side of the thermal conductivity calorimeters 6a and 6b on the upstream side and the downstream side is set to a higher temperature is appropriate. In this system, the two thermal conductivity calorimeters 6a and 6b are configured in series with the measurement line 19, but may be configured in parallel.

Next, in the system shown in FIG.
The thermal conductivity calorimeter 6 is configured as a single unit. In the thermal conductivity calorimeter 6, the two sensor units 10a and 10b are built in the above-described internal measurement flow path 9, and one of them is provided. The measurement temperature on the side is set high, and the set temperature on the other side is set low.

With this configuration, the sample gas flowing through the measurement line 19 is high on one side of the two sensor sections 10a and 10b while flowing through the measurement flow path 9 inside one thermal conductivity calorimeter 6, On the other side, the measurement of the thermal conductivity is carried out at a low temperature and at a high and low temperature.

In this system, two sensor units 1
If the measurement temperatures 0a and 10b are arranged at positions of the measurement flow path where the respective measurement temperatures do not affect the measurement temperature on the other side, they are arranged in either a series or parallel configuration with respect to the flow of the sample gas. You can also.

Next, in the system shown in FIG.
Is a single unit having one sensor unit 10. In this thermal conductivity type calorimeter 6, the sensor unit 10 has a variable measurement temperature. In the sensor unit 10 having the above-described configuration, the thin-film resistance
The measurement temperature can be changed by making the resistance value 6 variable.

With this configuration, the thermal conductivity of the sample gas flowing through the measurement line 19 is measured by the sensor unit 10 which is set to a higher temperature at a certain time, and is set to a lower temperature at another time. The thermal conductivity is measured by the set sensor unit 10, and thus the sensor unit 10
The measurement of the thermal conductivity at two high and low temperatures is performed by switching the measurement temperature at a predetermined time interval.

In addition, in the system shown in FIG. 7, the measurement temperature of the sensor section 10 is made continuously variable, and the measurement is performed by modulating the temperature with, for example, a sawtooth wave or a sine wave. The conductivity can be measured.

FIG. 8 shows the relationship between the temperature and the thermal conductivity of each component of the city gas. The thermal conductivity of each component of the city gas changes almost linearly according to the temperature. The higher the value, the higher the thermal conductivity. Therefore, it can be seen that even if the source gases have the same composition, the thermal conductivity differs depending on the temperature of the source gas at the time of measurement, that is, the temperature setting of the thin film resistor 16 described above.

As shown in FIG. 8, the rate of change of the thermal conductivity with temperature differs individually for each component. For example, in the case of the figure, methane greatly changes as compared with other components. For this reason, for example, the heat generation values are the same but the compositions are different.
When the thermal conductivity of each type of source gas is measured at two temperatures, high temperature and low temperature, the rate of change of the thermal conductivity at high temperature and low temperature increases, for example, as the methane concentration increases.

Conversely, when the compositions are the same and the calorific values are equal, the rates of change in the thermal conductivity at the two temperatures, high and low, are equal. That is, since the change in the composition of the source gas appears as a change in the rate at which the thermal conductivity changes at two temperatures, high and low, the output signal difference between the high and low two temperatures is calibrated for the source gas for which the true calorific value is known. High and low in time measurement 2
A calorific value close to the true calorific value can be obtained by comparing the difference with the output signal of the temperature and correcting the calorific value so as to eliminate the deviation. Therefore, next, a method of correcting the calorific value based on the measured thermal conductivity at two high and low temperatures will be described.

Table 1 simulates the variation of the calorific value of the two types of gas in the city gas supply system, and creates two types of the calorific value variation to be measured by the calorific value measuring method according to the present invention. (case 1, case 2) shows the composition of the mixed gas, in the table, C1 is CH _4, C2 is C ₂ H _6, C3 is C ₃ H _8, iC4 is iC ₄ H _10, nC4 is nC shows a ₄ H _10.

[Table 1]

Table 2 shows that the set temperatures in the sensor section 10 for the above two types of mixed gases are from 180 ° C. to 160 ° C.,.
It shows the sensor output voltage when the measurement is performed while changing the temperature to 0 ° C., that is, the measurement result of the terminal voltage of the thin film resistor 16.

[Table 2]

As can be seen from this table, the output voltage difference between the two types of mixed gases increases as the set temperature is lowered. This measurement is performed according to the following procedure.

From the above results, in this example, the high and low two temperatures are set to 180 ° C. and 120 ° C. The output signal at the temperature of 180 ° C. is used as the main signal, and the calorific value is calculated according to the above-described correspondence to produce the raw output. A value (main signal) is output, and a correction amount of the calorific value is obtained as described below using the output signal obtained by measuring the main signal at a low temperature of 120 ° C., and this is added to the calculated calorific value. And make corrections.

Assuming that the corrected output is Hcor and the raw output value at 180 ° C., that is, the main signal is H, the correction of the heat generation amount can be expressed as follows using the correction coefficient C. Hcor = CH (1) Hcor: output after correction H: raw output value (main signal) C: correction coefficient C is set as in the following equation. C = {V ₀ + a (V ₁ −V ₀ )} / V ₀ (2) V ₀ : 180 ° C / 120 ° C output voltage difference during calibration V ₁ : 180 ° C / 120 ° C output voltage during measurement Difference a: constant This is a constant a that is a ratio of the difference between the output voltage difference at the time of measurement and the difference between the output voltage difference at the time of calibration, that is, the raw material gas as a reference from which the calorific value is known, to the output voltage difference at the time of calibration. The correction coefficient C can be determined by determining the value of the constant a as an experimental value as described later. (2)
By transforming the equation and substituting it into equation (1), Hcor = ｛1 + a (V ₁ −V ₀ ) / V ₀ ｝ H (3), and ｛a (V ₁ −V ₀ ) / V ₀ ｝ H becomes , The correction amount to be added to the main signal H for correction. As described above, a is obtained as an experimental value. At this time, Hcor uses a calorific value calculated from a composition measured by gas chromatography as a true calorific value. That is, Table 2 is added to the above equation (3).
The constant a can be obtained by substituting the experimental values shown in the following as follows. V ₀ = 180 ° C. output voltage of composition of case 1−120 ° C. output voltage = 1.220398−0.4148020 = 0.805596 (V) V ₁ = 180 ° C. output voltage of composition of case 2−120 ° C. output voltage = 1.21619−0.4179382 = 0.8036808 ( V) H = raw output value of the composition of case 2 (main signal) = 10828.1 (kcal) Hcor = true calorific value of the composition of case 2 (measured value by gas chromatography) = 10940.5 (kcal) a = -4.3663 , This value of a is substituted into equation (3) to form a correction equation,
By inputting the output signal of the above-mentioned high and low 2 temperature into this correction formula,
The corrected heating value can be obtained.

Table 3 shows the results of measurement of the calorific values of the two types of mixed gas described above. During the output of the thermal conductivity calorimeter, +18 due to the specific configuration of the output signal system of the apparatus is shown.
The actual output includes the calorific value in parentheses () in which the deviation is reduced.

[Table 3] As shown in this table, in the raw output value of the thermal conductivity calorimeter, a measurement error occurs due to a change in composition,
The raw output value is corrected according to the output signal difference obtained by the measurement at two high and low temperatures, thereby canceling the error of the calorific value and measuring the calorific value with the same accuracy as the measurement by gas chromatography. It can be understood that can be performed.

As described above, in the thermal conductivity calorimeter according to the present invention, the calorific value can be accurately measured irrespective of the change in the composition, so that CO ₂ , N ₂ , and O _{2 in the} source gas can be measured.
And the like can be detected by a decrease in the calorific value. The time required to detect the mixing of such miscellaneous gases is as long as several minutes to tens of minutes in a gas chromatograph, but is as short as about several seconds in the present invention using a thermal conductivity calorimeter.

For this reason, when monitoring the mixture of the miscellaneous gas into the raw material gas by installing it in the raw gas line 1 of the city gas from the gas well to the mixing equipment 4, CO ₂ , When mixed gas such as N ₂ and O ₂ flows into the corresponding raw material gas lines 1a, 1b and 1c, it can be detected at a very high speed as compared with a gas chromatograph. The control instrument 3 is controlled by a signal to reduce or cut off the mixing ratio of the raw material gas supplied to the gas mixing equipment 4 via the raw material gas lines 1a, 1b, 1c, thereby performing transportation. Control for reducing the concentration of miscellaneous gas in the source gas transported via the conduit 4 can be reliably performed, and so-called off-spec gas delivery can be prevented.

[0047]

As described above, the present invention rationally utilizes a thermal conductivity calorimeter which is excellent in terms of response speed, explosion-proof property, temperature, pressure characteristics, etc. Since the mixture of the miscellaneous gas is monitored, the control for reducing the concentration of the miscellaneous gas in the mixing facility is realized with a high-speed response, and there is an effect that the delivery of the off-spec gas can be prevented.

[Brief description of the drawings]

FIG. 1 conceptually shows a raw material gas mixing system to which the method of the present invention is applied.

FIG. 2 is an explanatory diagram showing an internal structure of an example of a thermal conductivity calorimeter applied to the present invention.

FIG. 3 is an explanatory diagram showing a sensor unit of the calorimeter in FIG. 2 in an enlarged manner.

FIG. 4 is an explanatory diagram showing the correspondence between the thermal conductivity of various pure gases including a noncombustible gas and the sensor output of the calorimeter of FIG. 2;

FIG. 5 is an explanatory diagram schematically showing an example of a calorific value measurement system applied to the present invention.

FIG. 6 is an explanatory diagram schematically showing another example of a calorific value measuring system applied to the present invention.

FIG. 7 is an explanatory view schematically showing still another example of a calorific value measuring system applied to the present invention.

FIG. 8 is an explanatory diagram showing the relationship between temperature and thermal conductivity for each component of city gas.

FIG. 9 conceptually shows a conventional mixing system of source gases using a gas chromatograph.

[Explanation of symbols]

 Reference Signs List 1 (1a, 1b, 1c) Raw material gas line 2 Gas mixing equipment 3 Controller 4 Transport conduit 5 Gas chromatograph 6 (6a, 6b, 6c) Thermal conductivity calorimeter 7 Case 8 Constant temperature bath 9 Measurement flow path 10 Sensor unit DESCRIPTION OF SYMBOLS 11 Insulation material 12 Terminal box 13 Heater 14 Manifold 15 Silicon substrate 16 Thin film resistor 17 Diaphragm part 18 Temperature sensor 19 Measurement line

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-306014 (JP, A) JP-A-63-228052 (JP, A) JP-A-8-50109 (JP, A) Hiroyuki Muto , Measurement of calorific value of city gas by thermal conductivity analyzer, Saving Review, Yamatake Honeywell Co., Ltd., Japan, February 1, 1995, Vol. 13, NO. 1, P. 35-39 (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 27/00-27/24 G01N 25/00-25/72 JICST file (JOIS)

Claims (7)

(57) [Claims] 1. A thermal conductivity calorimeter for measuring a thermal conductivity of a gas at a predetermined temperature and measuring and calculating a calorific value from an output signal corresponding to the thermal conductivity according to a correspondence between the thermal conductivity and the calorific value. Is installed in the source gas line leading to the city gas mixing facility, and the measurement of heat conductivity is performed by monitoring the mixing of miscellaneous gases into the source gas based on changes in the calorific value .
Perform for high and low temperature, and output at the predetermined side temperature
The calorific value is calculated from the force signal, and the calculated
The amount is corrected according to the output signal difference between high and low temperature,
Detection of miscellaneous gas from the change in calorific value
Miscellaneous gas mixing monitoring method to natural gas feed in it using a thermal conductivity calorimeter, characterized in that 2. A coefficient obtained by multiplying the rate of change of the output signal difference between the high and low two temperatures during measurement with respect to the output signal difference between the high and low two temperatures during the measurement at the time of calibration for the raw material gas for which the true calorific value is known, by a constant. claim, characterized in that correcting the calorific value by adding a value obtained by multiplying the calorific value calculated by the corresponding relationship between the thermal conductivity and heat dissipation as a correction amount of calorific value, calculated heat quantity 1 Of monitoring impurities in city gas feedstock using the thermal conductivity calorimeter described 3. A heat conductivity type calorific value according to claim 2 , wherein the constant is obtained by substituting each output signal and a true calorific value in the measurement of the raw material gas whose calorific value is known into a correction formula. Monitoring method for impurity contamination in city gas feedstock using a gas meter 4. A thermal conductivity type calorimeter includes two units for setting the measurement temperature of the sensor unit high and those for setting the measurement temperature low.
It is characterized in that it is configured in parallel or series with the flow of the raw material gas and measures the thermal conductivity at two high and low temperatures.
A method for monitoring the contamination of city gas raw materials with impurities using the thermal conductivity calorimeter according to any one of claims 1 to 3. 5. A thermal conductivity type calorimeter includes a sensor section for setting a high measurement temperature and a sensor section for setting a low measurement temperature, and is configured in series or parallel to a gas flow. It is characterized by measuring the thermal conductivity at temperature
A method for monitoring the contamination of city gas raw materials with impurities using the thermal conductivity calorimeter according to any one of claims 1 to 3. 6. The thermal conductivity type calorimeter claim 1 for measuring the temperature of the sensor portion is variable by switching the measured temperature at predetermined time intervals, characterized in that the measurement of the thermal conductivity at high and low temperatures Method for monitoring contamination of city gas raw material with impurities using the thermal conductivity calorimeter according to any one of items 1 to 3 7. A thermal conductivity type calorimeter, the temperature measured by the sensor unit and a continuously variable, to claims 1 to 3, characterized in that it has a structure for measuring the thermal conductivity at the desired temperature Method for monitoring impurity contamination in city gas feedstock using the thermal conductivity calorimeter according to any one of the above items