JPS6118451Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a combustion gas analyzer, and in particular, the temperature detection part is improved.

As a type of gas analyzer, when a catalyst is used for a component to be measured in a sample, the heat of reaction from the catalyst corresponds to the content of the component to be measured, so there is a difference between the temperature change of the catalyst and the content of the component to be measured. Since there is a unique relationship between Examples of conventional temperature detection in this type of combustion gas analyzer are shown in FIGS. 1a, b, c, and d.

In the example shown in Figure 1a, a platinum wire 1 is used as a catalyst for the gas flow A, a contact reaction is carried out on the surface of the platinum wire 1, and the heat generated as a result of the reaction is received by the platinum wire 1 itself. The temperature rise caused by this is detected as a change in the electrical resistance of the platinum wire 1 itself. In this case, the electrical resistance itself is usually not measured, but the unbalanced voltage is measured using a Wheatstone bridge.

In the example shown in FIG. 1b, the platinum wire 1 is not used as a catalyst, but the platinum wire 1 is embedded in a carrier 2 such as alumina, and a catalyst layer 3 is formed on the surface of the carrier 2, which is provided in the gas flow A. The temperature rise of the catalyst layer 3 is controlled by the platinum wire 1.
Detected by changes in electrical resistance. The detection method is the first
This is the same as in Figure a.

In the example shown in FIG. 1c, a catalyst layer 3 is housed in a gas flow path 4 such as a quartz tube, and a resistance type temperature sensor 5 such as a thermistor or platinum wire is installed immediately downstream of this catalyst layer 3. As the temperature of the catalyst layer 3 increases, the temperature of the gas flowing through the catalyst layer 3 also increases, so the increase in gas temperature is detected by a change in electrical resistance. The detection method in this case is also the same as that in FIG. 1a.

In the example shown in FIG. 1d, a catalyst layer 3 is housed in a gas flow passage 4, and a temperature detector 6 such as a thermocouple is provided on the outer surface of the gas flow passage 4. Corresponding to the rise, the temperature of the gas flow passage 4 in the vicinity also rises, so the temperature of this gas flow passage 4 is detected by a temperature detector.

However, each of the above conventional examples has the following drawbacks. In FIG. 1a, the platinum wire 1 is
Because it is directly exposed to a high temperature of 600°C, the lifespan of the platinum wire 1 is short, 4 to 6 months. In Fig. 1b, since the temperature of the catalyst layer 3 is detected indirectly, the response time of temperature detection, that is, the response is, for example, 60% response.
It is quite slow (from 10 seconds to 10 seconds) and is difficult to detect with high sensitivity (microscopic content). Therefore, it is suitable as a gas detector as a gas analyzer. Similarly to FIG. 1b, the responses in FIGS. 1c and 1d are slow.

The object of the present invention is to provide a combustion type gas analyzer that eliminates the drawbacks of the prior art described above. In order to speed up the response, it is important to make the catalyst layer thin and to quickly measure the temperature rise in the catalyst layer, but the catalyst layer can be made thinner by using a vapor-deposited film, for example. The present invention is particularly focused on the rapid measurement of temperature rises, and devices such as semiconductor infrared sensors that use radiant heat to measure the temperature of an object to be measured have a quick response and high sensitivity. This is used to construct a combustion gas analyzer. Hereinafter, the present invention will be explained along with examples with reference to the drawings. In the drawings, the same parts as in FIG. 1 are given the same reference numerals.

FIG. 2 shows an embodiment of the present invention, in which a is a sectional view of a temperature detection portion and b is a block diagram of the entire combustion type gas analyzer. In FIG. 2a, 3 is a catalyst layer and 4 is a gas flow path. The catalyst layer 3 is a carrier 7
It is coated on the surface of a poor heat conductor such as quartz, which is attached to the inner surface of the gas flow passage 4 as a heat conductor. Reference numeral 8 denotes an infrared detector, which is provided penetrating the wall of the gas flow passage 4 on the side facing the catalyst layer 3 . 9 is a holder. According to such a configuration, the surface temperature of the catalyst layer 3 increases due to the heat generated as a result of the contact reaction on the surface of the catalyst layer 3, but infrared rays are radiated from the surface of the catalyst layer 3 in response to the surface temperature. By capturing this infrared rays with the detector 8, the surface temperature can be quickly measured. The output of the infrared detector 8 is introduced into the main body of the gas analyzer, and processed such as displaying the content of the component to be measured in the gas flow A. In FIG. 2b, 10 is a connection cable, and 11 is a gas analyzer main body.

FIG. 3 shows a specific usage example. Usually, the temperature detection parts are used in pairs, as shown in the figure. That is, a gas flow path 12 is provided which is separated from the gas flow path 4 and through which the gas flow flows, and the gas flow path 4 is equipped with a catalyst layer 3 and an infrared detector for detecting the temperature due to the desired catalytic reaction, as shown in FIG. 2a. 8, while the other gas flow passage 12 is provided with an inert catalyst layer 13 that does not cause a contact reaction and an infrared detector 14 for reference or compensation purposes. Note that 15 is a carrier. The outputs of both infrared detectors 8 and 14 are introduced into a differential calculator 16, so that the surface temperatures of the catalyst layers 3 and 13 are measured differentially. According to this example, even if there are fluctuations in the gas composition or flow rate in gas flow A, or fluctuations in the ambient temperature,
The output changes of both the infrared detectors 8 and 14 caused by these changes are equal and cancel each other out, and the measurement results are hardly influenced by the above-mentioned fluctuations, allowing accurate gas analysis.

As the infrared detector in the above embodiment, it is convenient to use a semiconductor infrared sensor in terms of compactness, but basically, various types can be used. Further, the infrared detector may not be placed directly in the gas flow path, but may be provided through quartz-based glass or the like that easily transmits infrared rays. Furthermore, the catalyst layer does not necessarily need to be formed of a vapor-deposited film, but it is better to be as thin as possible. Further, it is effective to provide a poor heat conductor between the gas flow path and the catalyst layer so that the heat of the catalyst layer does not escape to other places.

As specifically explained above with the examples,
Since the combustion gas analyzer of the present invention uses an infrared detector with a quick temperature response and high sensitivity for temperature detection, the content of the component to be measured can be measured with a quick response and even in trace amounts.

[Brief explanation of the drawing]

1A to 1D are explanatory diagrams showing examples of conventional temperature detection in a combustion gas analyzer, FIG. 2 is an embodiment of the present invention, and a is a sectional view showing the structure of the temperature detection part; b is an overall block diagram, and FIG. 3 is a sectional view showing another embodiment. In the drawing, A is a gas flow, 3 is a catalyst layer, 4 is a gas flow passage, 7 is a carrier, 8 is an infrared detector, 9 is a holder, 11 is a gas analyzer main body, 12, 13, 14 and 15 are for reference. a gas flow path, an inert catalyst layer, an infrared detector and a carrier, which constitute the temperature detection part of the
16 is a differential arithmetic unit.

Claims (1)

[Scope of utility model registration request] In a combustion gas analyzer that flows gas through a catalyst in which a component to be measured in the gas exhibits a catalytic reaction and measures the content of the component to be measured based on the temperature of the catalyst, a catalyst layer provided in the gas flow path and a catalyst layer provided in the gas flow path are used. Combustion characterized by comprising an infrared detector that detects radiant heat from the surface of the catalyst layer, and configured to determine the content of the component to be measured from the surface temperature of the catalyst layer measured using the infrared detector. type gas analyzer.