JPH06347401A - Infrared gas analyzer - Google Patents

Abstract

PURPOSE:To provide an infrared gas analyzer, which is compact and easy to be handled, with a low heat generation value of its light source. CONSTITUTION:Whose main body 14, makes opening/closing action straightly a shutter 11, is provided in its usually closed condition between a light source 8 and a cell 1 or between a cell 1 and a detector 10. When a power source is supplied to the light source 8 and a surface temperature of the light source 8 reaches a high temperature condition, which is suitable for measurement of constituent gas to be measured, the shutter 11 is opened, and then, the shutter 11 is closed after the lapse of a predetermined time, and at the same time, the power source supply to the light source 8 is cut off.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an infrared gas analyzer.

[0002]

2. Description of the Related Art FIG. 8 shows the structure of a conventional infrared gas analyzer. In this figure, 71 and 72 are measuring cells and comparison cells which are arranged in parallel with each other. However, both ends of each of the cells 71 and 72 are sealed with cell windows made of an infrared light transmissive material. The sample gas is supplied to the measurement cell 71 as shown by the arrow, and the comparison cell 72 is filled with a comparison gas such as zero gas that does not absorb infrared light. 73 are cells 71 and 7
A light source arranged on one end side of No. 2 irradiates the cells 71 and 72 with infrared light.

The detectors 74 and 75, which are arranged on the other ends of the cells 71 and 72, respectively, are infrared ray detectors that receive infrared light that has passed through the cells 71 and 72. 74 is provided with a bandpass filter 74a on its front surface, which passes infrared light in the characteristic absorption band of only the component gas to be measured (for example, CO ₂ ),
The detector 75 corresponding to the comparison cell 72 is provided with a bandpass filter 75a on its front surface, which passes infrared light having a wavelength where there is no absorption band for the measurement target component gas. A chopper 76 is arranged between the cells 71 and 72 and the detectors 74 and 75, and is driven by a motor (not shown).

In the infrared gas analyzer configured as described above, the light source 73 is turned on to emit infrared light into the cells 71 and 7.
When the sample gas is supplied to the measuring cell 71 while the chopper 76 is being rotated while irradiating the sample 2, the detectors 74 and 75 output detection signals, and these signals are processed by an arithmetic processing unit (not shown). By doing so, the concentration of the component gas to be measured can be obtained.

[0005]

However, in the above-mentioned conventional infrared gas analyzer, the light source 73 is always made to emit light and emit heat so as to have a temperature suitable for the measurement of the component gas to be measured before the measurement. Since the chopper 76 is rotated, it requires a considerable amount of time and power for preparation time before measurement and stabilization. That is, the conventional infrared gas analyzer should be called an energy consumption type. In addition, heat generated by causing the light source 73 to emit light or rotating the motor as described above causes the detector 7 to generate heat.
4 and 75, which causes the detector output to be affected by temperature drift. Further, since the chopper 76 is provided in addition to the light source 73, the cells 71 and 72, and the detectors 74 and 75, there is also a disadvantage that the entire configuration of the infrared gas analyzer becomes large.

The present invention has been made in view of the above matters, and an object thereof is to provide an infrared gas analyzer which is small in heat generation of a light source, compact, and easy to handle.

[0007]

To achieve the above object, the present invention provides a light source for irradiating the cell with infrared light at one end side of the cell to which the sample gas is supplied.
A detector that receives infrared light that has passed through the cell is provided at the other end of the cell, and in an infrared gas analyzer that measures the concentration of the measurement target component gas in the sample gas, between the light source and the cell or with the cell. Between the detector and the detector, a shutter whose main body opens and closes linearly is always closed, and power is supplied to the light source, so that the surface temperature of the light source is suitable for measuring the component gas to be measured. The shutter is opened when the temperature becomes high, and the shutter is closed after a lapse of a predetermined time, and at the same time, the power supply to the light source is turned off.

[0008]

In the infrared gas analyzer of the above construction, when the temperature of the light source is at a temperature suitable for measuring the component gas to be measured, the closed shutter is opened and closed for the time required for the measurement. At the same time as the shutter closing operation, the light emission of the light source is stopped. The time when the shutter is open, that is, the infrared light from the light source is irradiated to the cell within the measurement time, and the infrared light passing through the cell is provided with a sample signal element and a comparison signal element, for example. The light is received by the dual type pyrosensor, and the concentration of the component gas to be measured in the sample gas is obtained based on the difference between the outputs from the both elements.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 and FIG. 2 show an embodiment of the present invention. First, in FIG. 1, reference numeral 1 is a cylindrical cell made of a corrosion-resistant material such as stainless steel, and infrared light is provided at both ends thereof. It is sealed with cell windows 2 and 3 made of a transparent material, and an inlet 4 and an outlet 5 for sample gas are opened. The sample gas is introduced into the cell 1 through the introduction port 4 and is drawn out of the cell 1 through the introduction port 5 by an appropriate suction pump (not shown). In addition, 6 and 7 are flanges formed at both ends of the cell 1.

Reference numeral 8 denotes a light source which is provided at one end side of the cell 1 and emits infrared light, which is relatively small and has a light emission temperature change characteristic as shown in FIG. 5, for example. Reference numeral 9 is a light source holder. Reference numeral 10 denotes a detector provided on the other end side of the cell 1, which is composed of, for example, a dual type pyrosensor, and a measurement interference filter 10A and a comparison interference filter 10B (not shown) are described later on the two light receiving surfaces thereof. The cells are arranged so as to face the cell window 3 through the shutter 11 and to be arranged in a direction (direction perpendicular to the paper surface) orthogonal to the moving direction of the shutter 11 (the direction of the double arrow in the figure). Reference numeral 12 is a shutter holder, and 13 is a detector holder.

As the shutter 11, it is preferable that the shutter 11 is always closed and the movable portion thereof moves linearly when a signal is input. There is an "electromagnetic wave interrupting device" (Japanese Patent Application No. 4-193127) filed as of date.

FIGS. 6 and 7 schematically show the structure of the most basic double solenoid type electromagnetic wave interrupting device 30 of the electromagnetic wave interrupting devices according to the above patent application. Is a self-holding solenoid, which comprises fixed iron cores 33 and 34, coils 35 and 36 wound in the same direction, movable iron cores 37 and 38, and permanent magnets 39 and 40, respectively. These self-holding solenoids 31, 32 are arranged in a straight line with each other.

In this embodiment, for example, in the self-holding solenoid 31, the N pole is close to the movable iron core 37 so that the polarities of the magnetic poles of the permanent magnets 39 and 40 are opposite to each other. In 32, the S pole is arranged so as to be close to the movable iron core 38. Reference numeral 41 is a base frame for mounting and holding the self-holding solenoids 31, 32 in a predetermined positional relationship.

42 is the self-holding solenoid 31, 32
It is held by being connected to the movable iron cores 37 and 38 by a shielding portion provided between. The shield portion 42 is made of a material that shields electromagnetic waves such as light, for example, plastic, iron, aluminum, stainless steel, lead (effective for X-rays, etc.), and has an opening 44 in a part of the shield portion 43. . That is, the movable iron cores 37 and 38 and the shield 4
One movable body 45 is formed by 2. In addition,
Reference numeral 46 is a dual type pyrosensor including, for example, two light receiving elements 46a and 46b.

The electromagnetic wave interrupting device 3 configured as described above.
At 0, as shown in FIG. 7, the self-holding solenoid 3
1,32 coils 35 and 36 are connected in parallel to each other,
When these certain DC pulse signals (one-shot signals) are given to the coils 15 and 16, each self-holding solenoid 3
Magnetic fields in the same direction are generated in the coils 1 and 32.

Now, when the movable iron cores 37, 38 are in the positions shown by the solid lines in the figure and the light is reaching the detector 46, the DC power source 47 is connected as shown by the solid lines. Then, in the self-holding solenoid 31, a force that attracts the movable iron core 37 to the permanent magnet 39 side acts, and in the self-holding solenoid 32, a force that repels the movable iron core 38 from the permanent magnet 40 side acts. Then, the movable body 45 moves in the direction of the arrow indicated by the solid line, which moves the shielding portion 42 in the same direction, so that the detector 46 in the light receiving state is in the light shielding state. Then, in the self-holding solenoid 31, the movable iron core 37 is attracted to the permanent magnet 39 and holds that state.

On the other hand, when the movable iron cores 37, 38 are at the positions shown by the phantom lines and the detector 46 is in the light-shielded state, when the DC power supply 47 is connected as shown by the phantom lines, the self-holding solenoids 31, 32 are shown. , The movable body 45 moves in the direction of the arrow shown by the phantom line, and the shielding portion 42 moves in the same direction, so that the detector 46 in the light-shielded state receives light. It becomes a state. And
In the self-holding solenoid 32, the movable iron core 38 is attracted to the permanent magnet 40 and holds that state.

As described above, by inputting control signals of the same polarity to the coils 35 and 36, the movable iron cores 37 and 3 are
Since the movable body 45 composed of 8 and the shield portion 42 can be moved, the detector 46 can be switched from the light receiving state to the light shielding state or the opposite state. Then, if pulse-like control signals having different polarities are alternately applied to the coils 35 and 36, it can be used as a shutter or a chopper.

Therefore, in the infrared gas analyzer according to the above-described embodiment of the present invention, the electromagnetic wave interrupting device 30 operating under the above-described operation principle is further developed and applied.
A shutter 11 as shown in FIG. 1 is provided between the cell 1 and the detector 10. That is, in this figure, 14 is the shutter body, which corresponds to the movable body 45 in FIGS. 6 and 7. Further, 15 and 16 are the shutter body 14
Self-holding solenoids provided at both ends of the. Further, as shown in FIG. 2, two openings 14A and 14B are formed substantially in the center of the shutter body 14. The size of these openings 14A, 14B and the distance between them are matched to those of the filters 10A, 10B of the detector 10.

FIG. 3 is a diagram schematically showing an example of a circuit configuration in the infrared gas analyzer.

Next, the operation of the infrared gas analyzer having the above structure will be described with reference to FIGS. 4 and 5.

First, before starting the measurement, the shutter 1
1 is in a closed state. That is, the openings 14A and 14B of the shutter main body 14 are the filters 10 of the detector 10.
It is at a position different from A and 10B, and the light to the detector 10 is blocked.

When the button is operated to turn on the power in the above state (see FIG. 4B), the light source 8 emits light. At this time, the pump operates to supply the sample gas into the cell 1. The surface temperature of the light source 8 is almost 0 ° C. before the power is turned on, but when the power is turned on, the surface temperature of the light source 8 rises as shown by a curve I in FIG. At this time, the infrared light from the light source 8 passes through the cell 1 and proceeds toward the detector 10, but the shutter 1
Since 1 is closed, the infrared light does not enter the detector 10.

When the surface temperature of the light source 8 reaches a high temperature state suitable for measuring the component gas to be measured, for example, around 400 ° C., the shutter 11 operates and the shutter body 14
Moves, the openings 14A and 14B move to the positions of the filters 10A and 10B of the detector 10, and the shutter 11 is opened (see FIG. 4A).

The shutter 11 is opened for a time required for measuring the component gas to be measured, for example, for about 1 second, and then closed [see FIG. 4 (a)]. At the same time when the shutter 11 is closed, the power supply to the light source 8 is stopped [Fig.
(B)], the generation of infrared light stops.

The surface temperature of the light source 8 depends on the shutter 1
The temperature rises even after the opening of 1, and further rises slightly even when the power is not supplied, and when the peak (for example, about 410 ° C.) is exceeded, the temperature falls as shown by the curve II in FIG. In order to cope with the next measurement, it is desirable that the surface temperature of the light source 8 be lowered to near room temperature, but it may be about 50 ° C.

Although one measurement cycle is made up of the above steps, the control of such a measurement cycle is as follows.
This is performed in the microprocessor circuit 51 shown in FIG. That is, the time from when the light source 8 is turned on to when the surface temperature thereof reaches a temperature suitable for measurement can be set in advance by using a light emission temperature change characteristic graph as shown in FIG. Therefore, the desired operation can be performed by inputting the operation program of steps 1 to 3 into the microprocessor circuit 51 in advance.

The present invention is not limited to the above-described embodiments, but can be implemented with various modifications. For example, in the above-described embodiment, the intermittent measurement is performed, but a circuit that can be freely set such that the setting time of the one measurement cycle is 1 to 60 minutes is provided, and intermittent measurement and continuous measurement can be performed by switching the switch. Alternatively, the selection may be made alternatively.

The structure of the cell part may be a two-cell type having two cells. As the detector 10,
A thermistor type other than the pyro sensor, a thermal type sensor such as a thermoelectric stack, various semiconductor sensors, and a pneumatic type sensor such as a condenser microphone type sensor may be used.

By providing a plurality of sensors and an interference filter, it is possible to simultaneously detect a plurality of component gases to be measured. Further, the interference filter is generally provided immediately before the detector, but it may be provided between the light source 8 and the cell 1 or between the cell 1 and the shutter 11.

The shutter 11 may be provided between the light source 8 and the cell 1.

[0033]

As described above, in the infrared gas analyzer of the present invention, unlike the conventional infrared gas analyzer, the light source is turned on once without turning on the light source or rotating the chopper. By operating, for example, indoor CO ₂
Can be measured. Then, chopping can be performed by moving the shutter back and forth a plurality of times as needed, so that intermittent measurement or continuous measurement can be performed. Further, since the light source is turned on for a shorter time than the conventional one and the shutter operation time is also extremely short, the amount of heat generated is small. Therefore, the influence of temperature on the detector is greatly reduced, highly accurate measurement can be performed, and the energy consumption can be greatly suppressed.

The infrared gas analyzer of the present invention is compact and easy to handle, can be easily operated by anyone, and can easily measure, for example, the CO ₂ concentration at home or in the office. .

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an infrared gas analyzer according to the present invention.

FIG. 2 is a diagram showing an example of components of a shutter used in the infrared gas analyzer.

FIG. 3 is a block diagram showing an example of a control relationship in the infrared gas analyzer.

FIG. 4 is an operation explanatory view of the infrared gas analyzer.

FIG. 5 is a diagram showing emission temperature change characteristics of a light source used in the present invention.

FIG. 6 is a perspective view showing a configuration of an electromagnetic wave interrupting device that serves as the infrared gas analyzer.

FIG. 7 is a cross-sectional view schematically showing a main part of the electromagnetic wave interrupting device.

FIG. 8 is a diagram showing a configuration of a conventional infrared gas analyzer.

[Explanation of symbols]

1 ... Cell, 8 ... Light source, 10 ... Detector, 11 ... Shutter,
14 ... Shutter body.

Claims (1)

[Claims] 1. A light source for irradiating the cell with infrared light is provided on one end side of the cell to which the sample gas is supplied,
A detector that receives infrared light that has passed through the cell is provided at the other end of the cell, and in an infrared gas analyzer that measures the concentration of the measurement target component gas in the sample gas, between the light source and the cell or with the cell. A shutter whose main body opens and closes linearly is always provided between the detector and the detector, and power is supplied to the light source, whereby the temperature of the light source is suitable for measuring the component gas to be measured. An infrared gas analyzer characterized in that when the temperature becomes high, the shutter is opened, and after a lapse of a predetermined time, the shutter is closed and at the same time the power supply to the light source is turned off.