JPH0216867B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas calorimeter mainly used for measuring the calorific value of fuel gas.

In recent years, there has been a demand for continuous and instantaneous measurement of the calorific value of gas for the purpose of controlling the refining process of city gas, etc., or for trading purposes. A method has been proposed in which a fixed sensor is provided and the amount of heat generated by the reaction between the gas and the catalyst is detected as a change in the resistance value of a platinum wire or the like.

However, with such means, only a small portion of the gas comes into contact with the sensor, reducing measurement accuracy.In addition, when fixing the catalyst to a platinum wire, etc., it is necessary to apply a slurry of the catalyst and then sinter it. It is tied,
This requires a high level of technology, as the mechanical strength is weak due to the use of ultra-fine platinum wires, and the solvent left when making the catalyst into a slurry remains, which can have an adverse effect on the sensor. The disadvantage is that the reliability of the system deteriorates.

The present invention has an object of fundamentally solving the above drawbacks of the conventional calorimeter, and has a calorimeter that includes a powdery oxidation catalyst sealed in a gas passage and a temperature sensor that detects the temperature caused by the oxidation reaction of the oxidation catalyst. and a heat-retaining heater installed outside the oxidation catalyst enclosing part, and by controlling the heat generation status of the heater according to the detected power of the temperature sensor, the gas oxidation reaction in the oxidation catalyst can be controlled. Provides a highly reliable and extremely accurate gas calorimeter that measures the calorific value of gas by detecting the associated temperature, and prevents heat dissipation in the oxidation catalyst section by keeping it warm with an external heater. It is something to do.

Hereinafter, details of the present invention will be explained with reference to figures showing examples.

FIG. 1 shows a cross-sectional view. In the calorimeter 1, a circular tube made of pyrex glass or the like is used at both ends of a case 2 that forms a passage for gas G.
Branch pipes 2a and 2b are provided, and a temperature sensor RS is inserted into the case 2 on the side of the branch pipe 2a.
Alumina powder particles 3 are filled around this,
A temperature sensor SS is inserted into the case 2 on the side of the branch pipe 2b, and a powdery oxidation catalyst 4 is sealed around it.

In addition, the lead wires 5a and 5 of the temperature sensors RS and SS
b passes through the glass sealing parts 6a and 6b which are melted and filled into the end of the case 2 in an airtight manner, and is drawn out to the outside.

Incidentally, alumina powder particles 3 are filled between the oxidation catalyst 4 and the glass sealing part 6b, and glass wool 7 is filled in the gap and the branch pipes 2a, 2b.
is filled to fix each part and at the same time prevent leakage of the alumina powder particles 3.

Therefore, if gas G diluted with a combustion supporting gas such as air or oxygen is supplied from the branch pipe 2a,
Gas G passes through temperature sensor RS and reaches oxidation catalyst 4.
Here, an oxidation reaction occurs and reaction heat is generated, which is then discharged from the branch pipe 2b as exhaust gas RG. Therefore, the amount of heat of gas G can be determined by detecting the temperature caused by the oxidation reaction with temperature sensor SS. can.

However, the temperature sensor RS detects the temperature before the oxidation reaction, and due to its detection power,
If the detection power of the temperature sensor SS is to be corrected, the calorific value of the gas G can be determined accurately.

However, the heat generated in the oxidation catalyst 4 is
This causes a measurement error. Therefore, a heater H such as a nichrome wire is wound around the outside of the enclosure of the oxidation catalyst 4 through a heat insulating material 11 such as wool and a heat-resistant insulating material 12. These outer enclosures are surrounded by a cover 13 made of a heat-resistant and insulating material.

Note that a temperature sensor CS is inserted inside the heater H to detect the temperature of this portion.

Therefore, if the calorific value of the heater H is controlled in a direction in which the detection forces of the temperature sensors SS and CS become equal, the temperature difference between the oxidation catalyst 4 and the outside becomes zero, and
Since the heat generated by the oxidation catalyst 4 is not dissipated at all, the measurement result by the temperature sensor SS becomes extremely accurate.

Figure 2 is a circuit diagram of an attached circuit that displays the amount of heat based on the detection power of temperature sensors SS and SR and controls the energization of heater _H. Stabilized by diode ZD, temperature sensors SS, RS, CS and resistors
It is applied to each series circuit consisting of R ₂ to R ₄ , and if the resistance values of temperature sensors SS, RS, and CS change according to temperature, the terminal voltage of resistors R ₂ to _{R 4} also changes. The terminal voltage of resistors R ₃ and R ₄ is changed to the terminal voltage of resistors R ₅ and
Via _R6 , it is applied to the inverting and non-inverting inputs of the differential amplifier _A1 , which is provided with negative feedback by the resistor _R7 .
After determining the difference between the two inputs, it is given as a measurement output to the display circuit DP, thereby displaying the amount of heat of the gas G.

In addition, in order to control the energization to the heater H according to the detected power of the temperature sensors CS and SS and to prevent heat dissipation from the oxidation catalyst 4, the terminal voltages of the resistors R ₂ and R ₃ are set as follows.
It is applied via resistors R ₈ and R ₉ to the inverting and non-inverting inputs of differential amplifier A ₂ which is provided with negative feedback by resistor R ₁₀ , and the difference between both inputs is determined, and periodic switching operation is performed. This is applied to a control circuit CT using a thyristor or the like that performs this, thereby varying the angle of flow of current from the AC power source AC to the heater H.

Therefore, the heat generation state of the heater H is controlled in such a direction that the detection forces of the temperature sensors CS and SS are equalized, and heat dissipation from the oxidation catalyst 4 is prevented, so that the measurement results are maintained extremely accurately. Ru.

Note that in order to check the deterioration status of the oxidation catalyst 4, it is sufficient to detect the combustible components remaining in the exhaust gas RG. Either detect possible components or check the exhaust gas RG using a portable combustible gas detector.

Furthermore, if the oxidation catalyst 4 deteriorates, the amount of gas G supplied per unit time may be reduced so that all of the supplied gas G undergoes an oxidation reaction, allowing continuous use.

In addition, temperature sensors SS, RS, and CS include:
A tube made of alumina ceramic or the like with thin platinum wires sealed in it is suitable, and as the oxidation catalyst 4,
Cu ₂ O, C ₀ O, MnO ₂ , Cr ₂ O ₃ , ZnO, Fe ₂ O ₃ ,
Either V ₂ O ₅ , M ₀ O ₃ , etc. is used.

However, if you use a mixture of multiple types,
Since each characteristic acts complementarily, it is possible to obtain a more reliable oxidation reaction with respect to various combustible components, which is preferable.

Note that it is effective to mix inert particles such as alumina powder into the oxidation catalyst 4 because this prevents mutual bonding due to fusion of the granular oxidation catalyst and prevents a decrease in the surface area of the oxidation catalyst.

Therefore, a powdery oxidation catalyst 4 with a large surface area
Since everything in which gas G flows is in complete contact and all gas G participates in the oxidation reaction, the calorific value of gas G can be detected completely and accurately. Since this method does not require catalyst coating or adhesion, the overall reliability is greatly improved.

In addition, the shape of the heater H can be arbitrarily selected, the heat insulating material 11 may be omitted depending on the conditions, the shape of the cover 13 can also be arbitrarily selected according to the situation, and the configuration of the attached circuit Various selections can also be made depending on the conditions.

Case 2 may be made of any material as long as it has heat resistance, airtightness, and chemical inertness, and its shape can be selected. Various modifications are possible, such as using a semiconductor such as a thermistor or a thermocouple, and other substances exhibiting the same properties may be used instead of the alumina powder particles 3 and glass wool 7. .

As is clear from the above description, according to the present invention, an accurate and highly reliable calorimeter can be obtained with a simple and easy-to-manufacture configuration, so that continuous and instantaneous calorific value measurement of various combustible gases can be performed freely. As a result, remarkable effects can be obtained in terms of refining process management and trading of fuel gas, etc.

[Brief explanation of drawings]

The figures show an embodiment of the present invention, and FIG. 1 is a sectional view;
FIG. 2 is a circuit diagram of the attached circuit. 1...Calorimeter, 2...Case, 4...
Oxidation catalyst, 11...Insulating material, RS, SS, CS...Temperature sensor, H...Heater, G...Gas.

Claims (1)

[Claims] 1 Inert powder particles sealed on the gas passage entrance side,
A calorimeter having a first temperature sensor that detects the temperature before the oxidation reaction, an oxidation catalyst sealed on the exit side of the passage, and a second temperature sensor that detects the temperature due to the reaction of the oxidation catalyst; a third temperature sensor provided outside the oxidation catalyst enclosure; a heat-retaining heater provided outside the oxidation catalyst enclosure in the calorimeter in close proximity to the third temperature sensor; a heater temperature control circuit that controls energization of the heat-retaining heater in a direction such that detection outputs of the second temperature sensor and the third temperature sensor are approximately equal;
1. A gas calorimeter comprising: a temperature sensor; and a display means for displaying the amount of heat of the gas according to the detection output of the temperature sensor and the second temperature sensor.