JPH0518387B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) This invention relates to a parallel dust collection type dust radiation monitor.

(Prior art) Conventionally, a parallel dust collection type dust radiation monitor that collects dust in parallel using a single common pump and measures radioactivity concentrations at multiple sampling points in parallel has been used.
A device as shown in FIG. 6 is known. In this case, sampling lines 2a, 2b, . . . , 2n are each connected in parallel to one pump 1. Each sampling line 2a, 2b,..., 2n includes filter paper 3a, 3b,..., 3n, dust collection section 4a, 4b,
..., 4n, and flow rate adjustment valves 5a, 5b, ..., 5n are provided. And each sampling line 2
The flow rates of a, 2b, . . . , 2n are adjusted in advance to be predetermined.

When measuring the radioactive concentration at multiple points, the pump 1 is driven to suck the sampling gas into each sampling line 2a, 2b,..., 2n, and each filter paper 3a is placed in the dust suction section 4a, 4b,..., 4n. , 3b, . . . , 3n to adsorb radioactive dust in a sampling gas, and continuously measure the radioactivity in the radioactive dust.

In such conventional parallel dust collection type dust radiation monitors, when the filter paper of one sampling line needs to be replaced, the dust collection section of that sampling line is opened to the atmosphere and the necessary replacement work is carried out. I have to.

Therefore, if such a replacement operation is performed, when one sampling line is replaced, that line will be opened to the atmosphere, causing a pressure change in the entire system, and the flow rate in other sampling lines will change.

However, dust radiation monitors count the radiation of radioactive substances in the dust adsorbed on filter paper, assuming that the flow rate of each sampling line is constant, and calculate the radioactivity concentration in the sampling gas. Therefore, there was a problem that the flow rate error directly became a measurement error in the measurement result, making it impossible to accurately measure the radioactivity concentration.

(Problems to be Solved by the Invention) The present invention has been made in view of such conventional problems, and even when it becomes necessary to replace the dust adsorption means of one sampling line, The purpose of the present invention is to provide a parallel dust collection type dust radiation monitor that can be operated without changing the flow rate in each sampling line.

[Structure of the Invention] (Means for Solving the Problems) The parallel dust collection type dust radiation monitor of this invention has the following features:
A flow switching valve is provided in each sampling line, and a bypass line through which sampling gas or atmosphere passes with a flow rate equal to the flow rate of the sampling gas flowing through each sampling line is connected to each flow switching valve to switch between the sampling line and the bypass line. It was made so that it could be done.

(Function) In the parallel dust collection type dust radiation monitor of the present invention, the sampling line and the bypass line can be switched by each flow path switching valve, so that when the flow rate of sampling gas flowing through one sampling line changes, switch to the bypass line using the flow path switching valve to prevent flow rate changes from occurring in the remaining sampling lines.

(Example) Hereinafter, an example of the present invention will be explained in detail based on the drawings. FIG. 1 shows an embodiment of the invention.
In this embodiment, for one common pump 11, n sampling lines 12a, 12
b,..., 12n are connected in parallel. Each sampling line 12a, 12b,..., 12n has a filter paper 13a, 13b,..., 13n, a dust collecting section 14a, 14b,..., 14n, and a flow rate adjustment valve 1.
5a, 15b,..., 15n, and further a flowmeter 16
a, 16b, . . . , 16n are provided. When measuring the radioactivity concentration, the pump 11
to each sampling line 12a, 12
Each filter paper 13a, 13b,..., 1 is sucked in sampling gas by b,..., 12n, and is continuously supplied to the dust suction section 14a, 14b,..., 14n.
3n adsorbs radioactive dust in the sampling gas, and continuously measures the radioactivity in the radioactive dust.

Sampling lines 12a, 12b,..., 12
Between the flow rate adjustment valves 15a, 15b,..., 15n of n and the flow meters 16a, 16b,..., 16n, there are flow path switching valves 17a, 17b,..., 17n, respectively.
is provided.

Each sampling line 12a, 12b,...,1
2n has respective dust collecting sections 14a, 14b,
..., bypass line 18a on the upstream side of 14n,
18b,..., 18n are connected. The bypass lines 18a, 18b, . . . , 18n are provided with bypass flow rate regulating valves 19a, 19b, . and each bypass line 18
The outlet side ends of a, 18b, . . . , 18n are connected to each of the flow path switching valves 17a, 17b, .

Note that the pump 11 is equipped with a pump bypass valve 20.
is provided.

The operation of the parallel dust collection type dust radiation monitor having the above configuration will be described next. Each sampling line 1
The flow rate of the sampling gas flowing to 2a, 12b,..., 12n is determined by the flowmeters 16a, 16b,..., 16.
The flow rate adjustment valve 15 is adjusted so that the flow rate of the sampling gas in each line becomes a predetermined amount.
Adjust a, 15b,..., 15n. Also, bypass flow rate adjustment valves 19a, 19b,
..., 19n is adjusted.

Normally, each flow path switching valve 17a, 17b,..., 17
n is the sampling line 12 as shown in FIG.
a, 12b,..., 12n side, and by operating the pump 11, each sampling line 12a, 12b,..., 12n is connected to the dust collecting section 14a, 14b,..., 14n, and the flow rate adjustment valve 15.
a, 15b,..., 15n, flow path switching valve 17a, 1
A sampling gas is passed through 7b, . . . , 17n at a constant flow rate.

During this operation, the dust collecting sections 14a, 14b,...,
14n, filter paper 13a, 13b,..., 13
n adsorbs radioactive dust in the sampling gas. Therefore, each filter paper 13a, 13b,..., 13
Continuously measure the radioactivity concentration of the dust adsorbed on n, and constantly monitor whether the radioactivity concentration at each sampling point has become abnormally high.

In continuous monitoring, for example, a case may occur in which the filter paper 13a in one sampling line 12a is used up and needs to be replaced. In such a case, as shown in FIG. 2, the flow path switching valve 17a is switched to the bypass line 18a side, and the sampling line 12a is connected to the bypass line instead of passing through the dust collection section 14a and flow rate adjustment valve 15a. Sampling gas is allowed to flow through 18a.

If the flow path is switched by the flow path switching valve 17a in this way, the specific sampling line 12
Even if it becomes necessary to open the air to the atmosphere for replacement or adjustment of the filter paper 13a and the dust collecting part 14a in a, a preset flow rate of sampling gas can also be passed through the bypass line 18a to this sampling line 12a. It will be possible.

Therefore, the other sampling lines 12b,...,
12n does not affect the flow rate therethrough.

After the work on a specific sampling line 12a is completed, the flow path switching valve 17a is switched to the sampling line 12a side again to close the bypass line 18a and allow a predetermined amount of sampling gas to flow through the original sampling line 12a. do.

In this way, each sampling 12a, 12b,
Bypass lines 18a, 18 for ..., 12n
b,..., 18n are provided, and flow path switching valves 17a, 17
b, ..., 17n allows the flow path to be freely switched, so that the dust collection sections 14a, 14b, ..., 1 can be changed freely for a specific sampling line.
Even if it becomes necessary to open the section 4n to the atmosphere, the bypass lines 18a, 18b,..., 18
The sampling gas can be flowed at a constant flow rate through the sampling line, and adjustment or replacement work can be performed while maintaining the flow rate of other sampling lines at a constant level.

FIG. 3 shows another embodiment of the invention.
The feature of this embodiment is that the bypass lines 21a, 21
b,..., 21n, and outside air intake filters 22a, 22b,..., 22 are located at one end of each bypass line.
n is provided and opened to the atmosphere, and the outside air intake flow rate is adjusted by bypass flow rate adjustment valves 19a, 19b, . . . , 19n. Note that the same parts as in the first embodiment are designated by the same reference numerals.

In this embodiment, for example, when it becomes necessary to replace the filter paper 13a of the sampling line 12a or adjust the dust collection section 14a, the flow path is switched to the bypass line 21a side by the flow path switching valve 17a, and the flow path is switched to the bypass line 21a side. The sampling line 12a is also allowed to pass outside air at a flow rate equal to the sampling gas flow rate before switching, so that necessary operations can be performed without affecting the flow rates of the other sampling lines 12b, . . . , 12n.

FIG. 4 shows still another embodiment of the present invention, in which flow meter transmitters 23a, 23b,..., 16n in the first or second embodiment are replaced with flow rate indicating transmitters 23a, 23b,..., 23n, each of these flow rate indicating transmitters 23a,
23b, .
a, 17b, . . . , 17n.

In the case of this embodiment, as shown in FIG.
The control unit 24 monitors the flow rate fluctuation based on the output signal of the sampling gas flow rate, and when a fluctuation occurs in the sampling gas flow rate, the flow path switching valve 17a, 1 of the corresponding channel is
7b, . . . , 17n are automatically switched.

Therefore, a certain sampling line 1
Even in the case where the filter paper 13a in the sampling line 12a becomes clogged and the flow rate of the sampling gas flowing into the sampling line 12a is extremely reduced, the control section 24 receives the flow rate output signal from the flow rate indication transmitter 23a and controls the flow path. The switching valve 17a is automatically switched to the bypass line 18a side.

As a result, even if unexpected problems such as filter paper switching, filter paper clogging, or damage occur, and flow rate fluctuations occur, only the abnormal channel is automatically switched to the bypass line, and the remaining channels are automatically switched to the bypass line. This means that radiation monitoring can be continued automatically and continuously without fluctuations in the flow rate.

Note that this invention is not limited to the above embodiments, and various modifications can be made within the scope of the technical idea described in the claims.

[Effects of the Invention] Since the present invention has the above configuration, when the sampling gas flow rate of a particular sampling line changes significantly, the flow path is switched to the bypass line side using the flow path switching valve, and the original predetermined flow rate is changed. Able to maintain flow. Therefore, there is an advantage that accurate radiation monitoring can be performed without changing the flow rate of other sampling lines.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of an embodiment of the present invention, Fig. 2 is a system diagram showing the operation of the above embodiment, Fig. 3 is a system diagram of another embodiment of the invention, and Fig. 4 is a system diagram of an embodiment of the invention. FIG. 5 is a flowchart showing the operation of the above embodiment, and FIG. 6 is a system diagram of a conventional example. 11...Pump, 12a, 12b,..., 12n...
Sampling lines, 13a, 13b,..., 13
n...Filter paper, 14a, 14b,..., 14n...Dust collecting section, 17a, 17b,..., 17n...Flow path switching valve, 18a, 18b,..., 18n...Bypass line, 21a, 21b,..., 21n...Bypass Lines, 23a, 23b,..., 23n...Flow rate indication transmitter, 24...Control unit.

Claims (1)

[Claims] 1. In a parallel dust collection type dust radiation monitor in which sampling gas is taken in by a common pump in a plurality of sampling lines, each sampling line includes a dust collection section, a dust adsorption means, a flow meter, and a flow meter. A parallel collection comprising: a path switching valve; a bypass line through which a gas having a flow rate equivalent to the flow rate of the sampling gas passing through the dust collection section is connected to the switching valve; and the sampling line and the bypass line can be switched. Dust type dust radiation monitor.