JPS5852514Y2 - Gas concentration continuous monitoring device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a continuous gas concentration monitoring device that separates continuous detection signals from an infrared continuous gas concentration detection device having a plurality of cells and monitors each cell.

The continuous gas concentration detection device using the infrared method according to the present invention electrically detects the proportion of light absorption by the gas, that is, the gas concentration, by passing infrared rays into the gas in the cell, and also continuously detects the gas concentration at multiple locations simultaneously. As shown in Figure 1, an infrared light source 1, a radiation mirror 2 that reflects the light from the light source 1 and converts it into parallel light, and an infrared light source 1 that is parallel to the light A plurality of cells 3 are arranged on the same circumference, each having a pipe shape, and a light passage hole 4 is provided in front of each cell 3, and one light passage hole 4 is bored at an opposing position of each cell 3. A light shielding rotary plate 6 rotating at a constant speed is provided behind the cells 3, and the light passing through each cell 3 sequentially through the light passing hole 4 of the light shielding rotary plate 6 is 1
It consists of a condensing mirror 7 that focuses light on a point, and an infrared detector (photoelectric conversion element) 8 provided at the focal position of the condensing mirror 7.

Further, the cell 3 is, for example, A-M, as shown in FIG.
- When the cells in 1 are arranged at equal intervals, the gas flow at each point to be monitored is introduced into cells B-L, and only the atmospheric gas, which does not contain the measurement gas, is introduced into cell A. It is configured to allow light to pass through the cell M, and to block the inside of the cell M so that the light does not pass therethrough (A and MU do not necessarily have to be cells).

In the gas concentration continuous detection device configured in this way,
When the light-shielding rotating plate 6 is rotated at a constant speed, an electric signal in which the detection outputs of each cell 3 (A-M) are continuous is obtained from the infrared detector as shown in FIG. 5a.

This electrical signal is subjected to amplification and other appropriate processing and is transmitted via a single cable 9 to a monitoring device remote from the detection location that issues instructions and alarms.

In addition, in detecting the gas concentration, when the target gas is not contained in the cell 3, the electric signal obtained from the infrared detector 8 is as shown by the solid line in Fig. 3, indicating that the target gas is contained. In some cases, the area becomes smaller as shown by the broken line in the figure depending on the degree of the change, so this can be done by comparing the areas of the two.

The present invention time-divides the detection signal sent continuously through one transmission path from the infrared continuous gas concentration detection device configured as described above into detection signals corresponding to each cell 3, and The present invention provides a continuous gas concentration monitoring device that monitors each cell.

As shown in Fig. 4, the continuous gas concentration monitoring device according to the present invention has a group of analog switches in which analog switches ASI to ASn are respectively provided in parallel with respect to the input, and detects signal missing portions of continuous input signals. A signal loss detection circuit 10 consisting of, for example, a Schmitt trigger circuit or a monostable multivibrator, which generates a single pulse, and a monostable multivibrator that operates based on the output pulse of this signal loss detection circuit 10. These monostable multivibrators are connected in cascade so as to operate sequentially in synchronization with the falling edge of each output using the IVOO output as a trigger pulse, and each output causes the analog switches ASI to A
Monostable multivibrator MM that closes each Sn
VI~MMVn and the analog switch ASI~
Integrators 111 to 11 that integrate each output of ASn, respectively.
n and each integrator 1 using the output of the integrator 111 as a reference signal.
Differential circuit 121-12m that compares the outputs of 12-11n
(m2n-1) and these differential circuit outputs to the alarm circuit 14.
and a zero span circuit 13 that sends data to the indicator 15.

In the figure, MSI to MSm indicate indication changeover switches by the indication instrument 15.

The operation of the gas concentration continuous monitoring device according to the present invention configured as described above will be explained below.

For light shielding of the continuous detection signal with a period T shown in FIG. The signal deletion detection circuit 10 detects the signal deletion portion caused by the cell M.
is detected.

In this case, as shown in FIG. 3, the sensitivity of the infrared detector 8 is set so that even if the cell 3 contains a gas with a concentration of 100%, the detection signal does not become zero.

This signal deletion detection circuit 10 (ri) determines that there is a signal deletion and issues a pulse signal when the signal does not disappear even after time T1 has elapsed since receiving the signal from the previous cell L.

As a result, the monostable multivibrator MMVO operates and emits a pulse signal with a time width T2 as shown in the figure.

Next, the output of this monostable multivibrator MMVO serves as a trigger to sequentially operate the cascaded monostable multivibrators (1)/fV1-MMVn in the next stage.

The respective outputs of these monostable multivibrators MMVI to MMVn are as shown in FIGS. 5C to 5F.

That is, each output pulse is output at a timing corresponding to each signal of cells B to L, and with a time width T3 sufficient to compensate for each signal.

Therefore, each of these monostable multivibrators ■■
Analog switch A is selected depending on the output of 1 to ■■n.
When SI to ASn are opened sequentially, each analog switch A
Detection signals of cells A to L are obtained at the outputs of SI to ASn, respectively.

In this case, n in the symbol ASn means a number corresponding to the number in cells A-Lt, that is, the 12th analog switch.

Further, fluctuations in the rotational speed of the light shielding rotary plate 6 can be tolerated within a range in which each detection signal does not deviate from the time constant T3 of the monostable multivibrators 1 to 2n.

In this way, one cable 9 is connected to the gas concentration continuous detection device.
From the continuous detection signal transmitted in the cell A- Each detection signal corresponding to L is time-divided and extracted.

Each of the separated detection signals is integrated by integrators 111 to 11n to obtain each signal area, and each is processed by differential circuits 121 to 12n using the output of integrator 111 (detection signal of cell A) as a reference. be compared.

This comparison using the differential circuits 121 to 12m is performed in order to eliminate measurement errors caused by the temperature of the atmosphere of the measurement gas. I try to remove disturbances that have the same effect on the cell.

At this time, if temperature and other effects on the detection signal of each cell can be ignored, the differential circuits 121 to 1
2m is omitted.

When comparing without using the detection signal of cell A as a reference, an electric signal serving as a reference is set in advance using a separate setting device, and this set signal is compared with the detection signal of each cell.

If the detection signal of cell A is not used as a reference and a reference signal setting device is provided, the gas concentration can be measured by introducing a measurement gas flow into each cell A.

Next, each output of the differential circuits 121 to 12m, that is, cell B
Signals proportional to the gas concentration in -L are sent to the alarm circuit 14 via the zero span circuit 13, and when each signal exceeds a preset reference level corresponding to the allowable gas concentration, a buzzer 17 etc. issues an alarm. Emitted.

Furthermore, by simultaneously operating the changeover switches MSI to MSm, the gas concentration detected by each cell BL can be sequentially instructed by the indicator 15.

As described above, the gas concentration continuous monitoring device according to the present invention uses detection signals that are continuously sent from a gas concentration continuous detection device using an infrared method having a plurality of detection cells through a single cable made up of a pair of wires. It is possible to separate the gas concentration into detection signals corresponding to each cell and simultaneously monitor the gas concentration at multiple locations for each cell, and the configuration of the transmission means button and monitoring means for the gas concentration detection signal is inexpensive. This is particularly advantageous when the gas concentration detection point and its monitoring point are far apart.

[Brief explanation of drawings]

Fig. 1 is a front sectional view showing an example of an infrared continuous gas concentration detection device according to the present invention, Fig. 2 is a perspective view of the cell portion of the device shown in Fig. 1, and Fig. 3 shows how the gas concentration FIG. 4 is a block diagram showing an embodiment of the present invention, and FIG. 5 is a time chart showing the operation timing of each part in the embodiment. 3...Cell (A-L), 6...Light shielding rotating plate, 8...Infrared detector, 9...
Transmission cable, 10, ... Signal deletion detection circuit, 1
11~11n...Integrator, 121~12m...
... Differential circuit, 13 ... Zero span circuit, 1
4...Alarm circuit, 15...Indication instrument,
16...Amplifier, 17...Buzzer, A
S1~ASn0.100. analog switch, MMVO
-MMVn =...monostable multivibrator.

Claims (1)

[Scope of utility model registration request] A cell that blocks infrared rays and a gas airflow at each location to be monitored are introduced, and cells that allow infrared rays to pass are installed in parallel in the introduction section of the gas airflow, and each of the cells is sequentially irradiated with infrared rays while at the same time gas flow is introduced. In a continuous gas concentration monitoring device, the gas concentration continuous monitoring device is equipped with a detection device that continuously sends out a gas concentration signal having a signal missing portion through a single cable by electrically detecting the absorption rate of light by the gas concentration. an analog switch group in which a plurality of electronic switches are respectively provided in parallel for the signal; a signal deletion detection circuit for detecting a signal deletion portion of the gas concentration signal; and a detection signal of the signal deletion detection circuit. A plurality of cascade-connected monostable multivibrators that operate synchronously and sequentially and control the opening and closing of the analog switch group, an integrator that integrates each output of the electronic switch, and an integrator that integrates the output of each of these integrators. The gas concentration signal sent through the cable is time-divided by the analog switch group, and the gas concentration of each cell is continuously monitored. Features: Continuous gas concentration monitoring device.