JPS6191542A - Direct connection type non-dispersion infrared gas analyzer - Google Patents

Abstract

PURPOSE:To improve the response, by integrating a gas ejector, a sample gas cell and a sample gas passage as suction unit for a sample gas to be directly connected to a flue. CONSTITUTION:As a compressed air is jetted into a main conduit 30 through a gas ejector nozzle 29, a part of combustion exhaust gas is introduced into a pipe 30 as ample gas, a part of which is introduced into a sample gas cell 24 through a filter 25. Then, infrared rays radiated from a light source 34 enters the cell 24 passing through a correlation filter 36 and one transmission window 21 of the cell 24 and after reflected repeatedly between reflectors 23 and 22, it leaves the cell 24 via the other transmission window 21 to be made incident into an infrared detector 39 via a reflector 37 and a condenser 38. The infrared energy incident into the detector 39 is converted to electric energy to be displayed by arithmetic processing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an infrared gas analyzer that utilizes the absorption of infrared rays of a sample gas, and particularly relates to a non-dispersive type external optical gas analyzer that directly directs infrared rays from a light source without being dispersed. It is something.

(Prior art and its problems) Knowing the concentration of gases such as CO, CO, SO, etc. contained in combustion exhaust gas, atmospheric gas of an atmospheric furnace, etc. is important for environmental protection and quality control of energy-saving products. This is also an important point, and various measuring devices have been proposed in the past. Infrared gas analysis, which is one type of physical gas analysis, is one of these methods, and uses the infrared absorption of a sample gas to measure gas concentration.

Infrared gas analysis uses a prism to separate infrared rays!
There are two types: a dispersive type, in which the infrared rays from the light source are directly introduced, and a non-dispersive type, in which the infrared rays from the light source are directly introduced.The non-dispersive type is mainly used for industrial purposes because it is easy to manufacture.

However, conventionally known non-dispersive gas analyzers, for example, as schematically shown in FIG. The sample gas is separated from the gas, passed through filters 5 and 6 to remove dust in the sample gas, and then guided to an analysis section 8 via a pump 7 to detect the gas concentration.

In addition, a flow meter 9 is used to introduce a certain amount of gas into the analysis section 8.
was also needed. Since such a so-called gas sampling device is required separately, in conventional non-dispersive gas analyzers, the length of the sample gas conduit up to the analysis section 8 is inevitably long, and gas replacement in the analysis section is difficult. There is a problem that there is a delay between the actual gas concentration at a certain point and the measurement result of the analyzer, and that it is difficult to control the concentration of atmospheric gas or the like. In addition, since a sampling device consisting of various components was required, the analyzer itself was large in size, which not only limited the installation location of the analyzer, but also made it expensive, limiting its field of use. There was also the problem of putting it away. Furthermore, in order to prevent the filter from clogging, it is necessary to frequently inspect and clean the filter, and there are many problems that need to be improved in the inspection work.

(Means for Solving the Problems) In order to solve the above-mentioned various problems, the analyzer of the present invention detects changes in infrared rays absorbed by unique gas molecules contained in a sample gas. A non-dispersive gas analyzer that measures the gas concentration of a gas includes a main pipe connected to a probe having a sample gas inlet, and a sample gas cell installed horizontally to the main pipe and into which at least a part of the sample gas flows. , a gas ejector located downstream of the sample gas cell and sucking the sample gas, the sample gas cell having at least one transmission window for allowing infrared rays to enter and exit the sample gas cell; and at least one reflecting mirror for multiple reflection of the emitted infrared rays.

(Function) Therefore, in the infrared gas analyzer of the present invention, by ejecting an ejector driving gas such as compressed air into the main pipe from the nozzle of the gas ejector, the sample at the tip of the probe is protruded into the flue through which combustion exhaust gas passes. The sample gas is guided directly into the main pipe from the gas inlet without the need for special equipment such as a gas sampling device, and released into the flue along with the ejector driving gas from the sample gas return port provided at the other end of the main pipe. . At this time, a part of the sample gas introduced into the main pipe enters the sample gas cell through the filter and returns to the main pipe again. By the way, the infrared rays emitted from the light source are divided into reference light and sample light by a Cas correlation filter and enter the sample gas cell alternately at a fixed period.The reference light is absorbed by light of a specific infrared wavelength of the gas to be measured. Therefore, the light is emitted from the sample gas cell without being absorbed by the gas to be measured in the sample gas cell. On the other hand, sample light having a specific infrared wavelength is absorbed by the measurement gas in the sample gas cell depending on the gas concentration. Therefore, the gas concentration can be determined by comparing the difference in light intensity between the reference light and the sample light that has passed through the sample gas cell. In addition, concave surfaces facing each other are arranged inside the sample gas cell, and multiple reflections occur, increasing the contact distance between the sample gas and infrared rays without increasing the length of the sample gas cell, improving measurement sensitivity. .

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment of the analyzer of the present invention, in which an analyzer 20 is attached directly to, for example, a flue wall 12 of a flue 10 through which combustion exhaust gas flows. The analyzer 20 includes a gas introducing means for guiding a portion of the gas in the flue into the sample gas cell, and an optical means for guiding infrared rays emitted from a light source and passed through the sample gas cell to an infrared detector 39.

The gas introduction means includes a main pipe 30 having a substantially U-shape, a sample gas cell chamber 24 installed horizontally in the main pipe 80, and a gas ejector located downstream of the sample gas cell. One end of the main pipe 30 is connected to a probe 82 having a sample gas inlet protruding into the flue 10, and the other end is connected to a sample gas return port 33 opening into the flue downstream of the probe 32. Therefore, for example, when compressed air is ejected from the gas ejector nozzle 29 into the main pipe 30 as an ejector driving gas, a flow shown by arrow A in the figure is generated, and a part of the combustion exhaust gas is transferred to the main pipe 30 as a sample gas.
Guided within 0. A portion of the sample gas introduced is 1.
Since the sample gas enters the sample gas cell 24 through the filter 25 as shown by arrow B in the figure and returns to the main pipe again, there is no need to separately process the introduced sample gas.

The optical means includes a light source 34 that emits infrared light, and a gas correlation filter 3 that divides the emitted infrared light into reference light and sample light.
6, a synchronous motor 35 that rotates the gas correlation filter 36 at a constant speed, a condenser 38 that condenses infrared light emitted from the sample gas cell, and an infrared detector 39 that detects the condensed infrared light. . Note that in order to arrange the main pipe, sample gas cell, etc., or to make the analyzer itself more compact, if the optical path of infrared rays is changed, a reflector may be used. In this embodiment, a reflector 37 is used to The path of the emitted light is changed by 90 degrees.

Here, the sample gas cell 24 multiple-reflects the infrared rays that have entered the cell, that is, reflects them repeatedly to increase the contact distance between the sample gas in the cell and the infrared rays.
Concave reflecting mirrors 22, 2.3 arranged to face each other, and a transmission window 21.21 for allowing the red light beams that have passed through the correlation filter 36 to enter and exit the sample gas cell.
and.

Therefore, the infrared rays that have passed through the correlation filter 36 are shown by the arrow C in the figure.
As shown, the light passes through one transmission window 21 and enters the cell, is repeatedly reflected between reflection mirrors 23 and 22, passes through the other transmission window 21, exits from the cell 24, and is emitted from the reflection mirror 37,
The light passes through a condenser 38 and reaches an infrared detector 39 . The detector 39 then converts the incoming infrared energy into electrical energy. This is processed and displayed on the indicator. Therefore, according to the analyzer of the present invention, the contradictory conditions of increasing the contact distance between the sample gas and infrared rays and shortening the total length of the sample gas cell 24 can be solved at the same time.

Furthermore, in this embodiment, a heater 81 is provided around the main pipe aO and the sample gas cell 24 in order to prevent dew condensation in the passage through which the sample gas flows. It is not necessary to provide .

Reference numeral 40 indicates a calibration gas tube for guiding gas into the sample gas cell 24 to a standard required when calibrating the analyzer. During calibration, standard gas is introduced into the sample gas cell through this gas tube. 4 and fill the cell 24 with standard gas to calibrate the indication.

FIGS. 2 and 4 show other preferred embodiments of the present invention. For the sake of brevity, the same reference numerals are given to the same or equivalent parts as in Fig. 1.

In the embodiment shown in FIG. 2, in order to facilitate replacement of the sample gas entering the sample gas cell 24 from the main pipe 80, one end of the sample gas branch 'lIl' 26a is
connected to the sample gas cell 24 at a distance from the main pipe 30;
The other end of the sample gas branch pipe 26 is connected to the sample gas cell 24.
The configuration is such that the main pipe 80 is connected to the downstream main pipe 80. Note that the other end of the sample gas branch pipe 26, in which only a portion of the sample gas branch pipe is illustrated for simplicity, is connected to the main pipe 30 downstream of the sample gas cell 24 and upstream of the gas ejector 29, as in this embodiment.
Although not limited to, the flow of the sample gas within the sample gas cell is constant, and the efficiency of inflow of the sample gas into the sample gas cell 24 by increasing the length of the branch pipe 26 If consideration is given to the fact that the voltage decreases, it is better to communicate with each other as in this embodiment.

Further, in this embodiment, a gas amount regulator 27 for adjusting the flow rate of the sample gas is provided in the sample gas branch pipe 26 near the sample gas cell 24.

In this embodiment, the gas amount regulator 27 is composed of a valve body that can fit into the branch pipe 26, and mechanically or electrically controls the valve opening. J: Can adjust 4 times.

Therefore, in this embodiment, the gas entering the sample gas cell is quickly replaced, so that a non-dispersive infrared gas analyzer with quick response can be obtained.

This situation is shown in FIG. Here, the sample gas flow rate refers to the gas flow rate flowing into the main pipe 30 from the probe 32, and the response time refers to the sample gas inlet 41 of the probe 82.
When switching gases, this is the 90% response time until the output of the analyzer 20 reaches a stable state. As can be clearly seen from FIG. 3, the response time of the analyzer of the present invention is less than % of that of the conventional apparatus which requires a separate sampling device. In particular, when the gas amount regulator 27 is fully opened in an apparatus equipped with a branch pipe, the response is approximately % of that of a conventional analyzer, and it can be seen that the response is significantly improved.

In the embodiment shown in FIG. 2, the Persil 28 for removing adhering dust attached to the main pipe, sample gas cell, filter, etc. upstream from the gas ejector nozzle 29 is installed in the main pipe upstream from the gas ejector nozzle 29. 30. By jetting pressurized fluid such as compressed air into the main pipe 30 through the persilo 28, attached dust is removed from the inside of the analyzer. Furthermore, when an abnormality occurs in the analyzer, pressurized fluid is ejected from the purge port to prevent the swarm gas from entering the analyzer, and also to prevent moisture in the sample gas from condensing within the analyzer. Preferably, by arranging the persilo 28 and the sample gas inlet 41 on a straight line, the efficiency of removing attached dust can be further improved.

Therefore, in an analyzer having such a purge port, during normal maintenance work, 1. <-Shiro 28
Since it is only necessary to eject pressurized fluid from the analyzer to remove attached dust and perform mechanical cleaning about once a year, maintenance and inspection work can be greatly simplified compared to conventional analyzers.

Another preferred embodiment of the present invention, shown in FIG. 4, connects the main pipe 80 and the sample gas cell 24 via branch pipes 26b, 26b spaced apart from each other when the sample gas cell 24 is installed horizontally in the main pipe 30. It is connected. Therefore, a part of the sample gas that has passed through the probe 32 and flowed into the main pipe 30 passes through the filter 25, passes through the upstream branch pipe 26b, flows into the sample gas cell, and flows into the downstream branch pipe 261, as shown by arrow B in the figure. ) to the main pipe 30. Note that it is preferable to arrange the gas amount regulator 27 near the filter 25 of the upstream branch pipe 26b so that the flow rate of the sample gas flowing into the sample gas cell 24 can be adjusted.

Furthermore, as in the embodiment shown in FIG. 2, it is possible to improve the efficiency of removing attached dust by aligning the Persil 28 with the sample gas inlet 41.

(Effects) As detailed above, according to the direct-coupled non-dispersive infrared gas analyzer of the present invention, the gas ejector as a sample gas suction device, the sample gas cell, and the sample gas flow path are integrated into an integrated structure directly connected to the flue. Therefore, pretreatment devices such as a pump for sucking sample gas and a drain pump for removing water, which are indispensable for conventional non-separating infrared gas analyzers, can be omitted. Furthermore, since the structure is directly connected to the flue, the sample gas flow path is shortened, and gas replacement in the sample gas cell is facilitated, thereby improving the responsiveness of the analyzer. Furthermore, by connecting a branch pipe equipped with a gas volume regulator to the sample gas cell, the response can be further improved, and by adjusting the gas volume regulator, the response time of the analyzer can be changed. Therefore, even if the pressure loss of the filter due to dust adhesion becomes large, the response time can be corrected, and the analyzer has a high degree of flexibility as it can always maintain a substantially constant response.

In addition, concave reflecting mirrors are placed in the sample gas cell so as to face each other and are spaced apart, and the infrared rays emitted from the light source are reflected multiple times between these mirrors, and then enter the infrared detector. Since the 't' configuration is adopted, the length of the sample gas cell can be shortened, and the analyzer can be made smaller and lighter. Furthermore, since a sufficient contact distance between the sample gas and the infrared rays can be ensured, measurement sensitivity is not impaired.

Further, by blowing out pressurized gas such as compressed air from the purge port, adhering dust adhering to the sample gas cell, filter, and main pipe can be easily removed, so maintenance and inspection work can be simplified.

By providing a heater around the sample gas flow path, it is possible to reliably prevent moisture in the sample gas from condensing. When an abnormality occurs in the analyzer, compressed air or the like is jetted out from the purge port to prevent the sample gas from entering the analyzer, thereby preventing moisture contained in the sample gas from condensing inside the analyzer.

Note that the present invention is not limited to the embodiments described above, and various modifications are possible. For example, a solenoid valve may be interposed in a conduit for supplying pressurized gas ejected from a purge port, and this solenoid valve It is also possible to open and close in response to a temperature signal from a sample gas cell, an abnormality signal from an analyzer, a check signal from an analyzer, or the like.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an embodiment of the direct-coupled non-dispersive infrared gas analyzer of the present invention, FIG. 2 is a schematic cross-sectional view showing another preferred embodiment of the analyzer of the present invention, and FIG. , a diagram showing a comparison of response times between the analyzer of the present invention and a conventional analyzer, FIG. 4 is a schematic cross-sectional view showing another preferred embodiment of the analyzer of the present invention, and FIG. 1 is a diagram schematically showing the configuration of a conventionally known analyzer. 2.7...Suction pump 3,4...Drain pot 5.6...Filter 8...Analysis section 20
,...Analyzer 21...Transmission window 22.28
．． 27...Reflector 24...Sample gas cell 25...Filter 26a, 26b,...
Branch pipe 27...Gas amount adjustment 8328...Persillo 2
9...Gas ejector nozzle 3o...Main 28 pipe 3
1... Heater 32... Probe 38.
...Sample gas return port 34...Infrared light source a5...Synchronous motor 3
6... Gas correlation filter 88... Concentrator 89...
・Infrared detector 40...Calibration gas tube 41...
Sample gas inlet

Claims (1)

[Claims] 1. A non-dispersive gas analyzer that measures the gas concentration of a specific gas by detecting changes in infrared rays absorbed by specific gas molecules contained in a sample gas, comprising: a sample gas inlet; A main pipe connected to the probe, a sample gas cell installed horizontally in the main pipe into which at least a portion of the sample gas flows, and a sample gas cell located downstream of the sample gas cell that sucks the sample gas by ejecting pressurized fluid. a gas ejector; the sample gas cell includes at least one transmission window for allowing infrared rays to enter and exit the sample cell; and at least one reflection window for multiple reflection of the infrared rays that have entered the sample gas cell. A direct-coupled non-dispersive infrared gas analyzer characterized by comprising a mirror. 2. The infrared gas analyzer according to claim 1, in which the sample gas cell and the main pipe downstream of the sample gas cell are communicated via a sample gas branch pipe for direct-coupled non-dispersive infrared gas analysis. Total. 3. The infrared gas analyzer according to claim 1, wherein the sample gas cell is connected to the main pipe through branch pipes separated from each other. 4. In the infrared gas analyzer according to claim 2 or 3, the branch pipe and the sample gas branch pipe are equipped with a gas amount regulator for adjusting the gas flow rate. Total. 5. In the infrared gas analyzer according to any one of claims 1 to 4, a purge port is provided in the main pipe upstream of the ejector, and purge gas is spouted from the purge port. A direct-coupled non-dispersive infrared gas analyzer that removes dust attached to the main pipe, sample gas cell, etc. 6. In the infrared gas analyzer according to any one of claims 1 to 5, heating for maintaining the sample gas flow path in the gas analyzer at a temperature equal to or higher than the dew point temperature of the sample gas. A direct-coupled non-dispersive gas infrared analyzer, wherein a means is provided in at least a portion of the flow path.