JPS63250595A - Activated-carbon rare-gas adsorption-capacity test apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to the noble gas adsorption of activated carbon filled in an activated carbon type rare gas hold-up device that adsorbs and removes rare gases from radioactive gaseous waste. This invention relates to an activated carbon noble gas adsorption test device for testing the performance of activated carbon.

(Prior art) In nuclear couplants, especially boiling water nuclear power plants,
Radioactive rare gases such as krypton and xenon generated in the nuclear reactor are extracted from the turbine condenser to the gaseous FN waste treatment system. After being subjected to delayed attenuation processing using a rare gas bold-up device, it is released into the atmosphere.

However, it is necessary to confirm that this activated carbon rare gas hold-up device has sufficient delay performance.
The adsorption capacity of activated carbon is tested periodically before and after plant startup.

The conventional method for testing activated carbon's rare gas adsorption capacity was to use an activated carbon rare gas test device as shown in Figure 2 to measure the concentration of radioactive Kr-85 as a tracer. .

That is, the tracer Kr-8 is supplied from the Kr gas supply device 3 of the activated carbon rare gas adsorption capacity testing device 2 to the upstream side of the activated carbon rare gas holding up tower 1 disposed in the gaseous waste treatment system.
A constant amount of Kr gas containing 5 is injected into the system in a pulsed manner through valve 4. The injected K-85-containing gas is carried by the air flowing through the system and passes through the activated carbon rare gas hold up towers 1 while being sequentially held up.Meanwhile, each activated carbon rare gas hold up tower 1.1・・・
The gas passing through each group is sampled into the ionization chamber 7 by the sampling pump 6 by sequentially opening and closing the valves 5.5... from the outlet side of the sample gas.
The change in W4 degree over time is measured by the radiation measuring device 8.

The adsorption capacity of activated carbon is evaluated using systematic meteor f (m3/h), K
At the time th (h) when the r-85 concentration reaches its peak, compare the value of the dynamic adsorption coefficient K (m'/1on) obtained from the activated carbon M M (ton) using the following formula [I] with the reference value. This is done by

K=thi/M・・・・・・・・・・・・［I］However, since the conventional method uses a radioactive isotope called K r-85 (RI>) as a tracer, the test @ device uses RI. As a result, the use of R1 is subject to various restrictions such as the establishment of radiation control areas and radioactive leakage countermeasures.As a result, in addition to prolonging the test period and increasing test costs, especially before plant startup, This had the disadvantage of imposing restrictions on plant construction and testing, which had a negative impact on the plant construction period and cost.

In addition, the concentration of Kr-85 used in the test is higher than the extremely small rare gas concentration during actual plant operation in order to increase detection sensitivity, and it is also in line with the nuclear facility's policy of suppressing RI emissions. It was undesirable.

In view of these circumstances, an activated carbon noble gas adsorption capacity testing device as shown in FIG. 3 using non-radioactive krypton has been proposed (for example, Japanese Patent Laid-Open No. 60-2}8064).

That is, in FIG. 3, on the upstream side of the activated carbon rare gas holding up tower 1, a non-radioactive gas whose flow rate is adjusted by the regulating valve 11 is supplied in a pulsed manner from the krypton supply device 10 of the activated carbon rare gas adsorption capacity testing device 7i9. After that, each activated carbon rare gas hold up tower 1.1.
The sampling pump 6 sequentially opens and closes the valves 5, 5, and so on from the outlet side of the sample gas supply pipe 12.
A sample gas is introduced into the sampler 14, and the valve 13 is periodically opened to sample the sample gas into the sampler 14.The sample gas sampled by the sampler 14 is injected into the sample inlet of the gas chromatography 15, and the Kr concentration is analyzed.

In addition, the reference numeral 16 in the figure is a carrier gas supply device that supplies carrier gas to the gas chromatography 15.

In this method, gas sampling and Kr151 degree analysis by chromatography are performed in batch processing, but in the concentration range where the adsorption form is tlenary type, the time-concentration curve becomes a Gaussian distribution, so each time The data obtained by sampling is fitted to a Gaussian distribution to determine the time th at which the Kr concentration reaches its peak, and the adsorption capacity of activated carbon is evaluated using the formula [I].

(5F, the problem that Akira is trying to solve) In order to improve the accuracy of the test, it is necessary to regulate the sampling interval,
It is also important to automate the test so that accurate measurements can be made even at random sampling intervals. In the method of batchwise measuring KrjM using non-radioactive Kr using gas chromatography as described above, it goes without saying that the greater the number of data points, that is, the shorter the sampling interval, the better the accuracy of the test. The interval depends on the time required for gas chromatography analysis.

In other words, gas chromatography passes an analyte gas through a long and narrow column filled with an adsorbent such as activated carbon.
Taking advantage of the fact that the hold amplifier time differs depending on the type of gas, the analyte is separated into each individual gas, and a detector at the column outlet detects the characteristic of thermal conductivity, etc., and calculates the retention time and peak of each peak. The type and concentration of gas are determined from the height. However, one analysis ends after all the gas components in the injected sample gas have passed through the column, so if the sample gas contains gas components with long retention times, the analysis time will be longer, and therefore the sampling time will be longer. The interval will also become longer.

In an activated carbon noble gas adsorption test in a gaseous waste treatment system of an atomic couplant, clean air, such as instrument air, is normally flowed through the system. The composition of air is 78% N2
．． 2}% 02.0.9% Ar, 0.03X CO2 and the weight of Ne, He, etc. If you add `` to this and apply it to gas chromatography, a chromatogram as shown in Figure 4 will be obtained. That is, in Fig. 4, the horizontal axis t
represents time (retention time), and the vertical axis represents the detected peak height. The peak of K' is detected as the peak already shown in the figure, and appears immediately after the peak a of N2 and 02.

On the other hand, as shown by C in the figure, the peak of CO2 appears much later than the peak of Kr and other air composition gases, so
For one gas chromatography analysis, the CO2 detection end time (Te3) should be used.

Therefore, it is necessary to set the sampling interval to T c 2 or more. In other words, the sampling interval 1゛ is Tc2
In the case shown in FIG. 5 described below, the peak ``'' is not detected in the 12th sampling, which overlaps the peak ``b' of ``, even though the peak of CO2 is obtained by the first sampling.

As mentioned above, in one gas chromatography unit, C0
In order to avoid interference due to the peak of 2, it is necessary to set the sampling interval to Tc2 or more, and it has been difficult to shorten the sampling interval and improve the accuracy.

Furthermore, when automating a testing device and increasing sampling frequency, it is important to automate a series of sampling operations and eliminate operational errors caused by complicated operations in order to improve testing accuracy.

In the activated carbon rare gas adsorption capacity test device indicated by the reference numeral 9 in FIG. In order to inject into the gas chromatography 15 against the pressure of , it is necessary to inject under pressure using, for example, a piston mechanism. Furthermore, the sampler 14 requires a backflow prevention mechanism from the gas chromatography 15 side and an am shade for cleaning residual gas in the sampler 14 in preparation for the next sampling, making the structure complex and the operations complicated. .

If multiple gas chromatographs are added to this equipment, the number of operating parts will increase, making it more complex.If a series of sampling operations is to be automated, there will be many operating parts, making control complex, which increases the cost of the test equipment. be.

[Structure of the Invention] (Means for Solving the Problems) As a means for solving the above problems, as shown in FIG. 1, a plurality of gas chromatographs 15a and 15b are provided,
A sample gas meter 22 whose inlet side is connected to the sample gas supply pipe 12 and the carrier gas introduction pipe 18 and whose outlet side is connected to the sample gas discharge pipe 19 and the sample gas transfer pipe 20 via a six-way switching valve 2}; Sample gas transfer tube 2 on the side
0, the carrier gas introduction branch g23, the multi-way switching valve 24 whose outlet side is connected to the sample injection ports of the plurality of gas chromatographs 15a and 15b, the hexagonal switching valve 2} and the multi-way switching valve 24 at regular intervals, A rotary sampling device 26 is provided which includes a controller 25 that switches the gas chromatographs 15a and 15b, and a sampling pump 6 is provided in the sample supply pipe 12.

The setting time for switching the six-way switching valve 2} and the multi-way switching valve 24 is expressed by the following formula [1].

T=T^/n ・・・・・・・・・・・・・・・［1］
TA: Time required for one gas chromatography analysis (Tc2 or more) n: Number of gas chromatographs In addition, the controller 25 is provided with a limer function.

(Operation) The operation of the above means will be explained using a case where gas chromatography is 2-white as an example.

In Figure 1, the sample gas is
The six-way switching valve 2} is continuously sent to the sample gas meter 22 as shown by the solid line, and the inside of the sample gas meter 22 is cleaned and gas replaced.

On the other hand, the carrier gas is continuously supplied to the gas chromatographs 15a and 15b from the sample gas transfer pipe 20 and the carrier gas introduction branch pipe 23 via the four-way switching valve 24.

At each interval set in the controller 25, the six-way switching valve 2
} is switched as shown by the dotted line for a certain period of time required to send the gas in the sample gas meter 22 to the gas chromatographs 15a and 15b, and the sample gas in the sample gas meter 22 is switched to the carrier gas. is transported to the gas chromatograph 15 via the four-way switching valve 24.
a, 15b.

The four-way switching valve 24 is switched at the same time as the six-way switching valve 2} at intervals set in the controller 25, and the solid line and dotted line flow paths shown in the figure are alternately configured, so that the sample gas is transferred to the gas chromatographs 15a and 15b. Supplied alternately.

At the same time, the gas chromatographs 15a and 15b are also reset alternately by a signal from the controller 25, and a new analysis is started.

Since sample gas is alternately supplied to the gas chromatographs 15a and 15b at intervals of (TA/2) by the four-way switching valve 24, the time for one analysis of one gas chromatograph is TA/2X2 = T8. secured, C
02 peaks do not overlap, and the K' peak is detected.

On the other hand, since the sampling interval is the switching interval TA/2 of the six-way switching valve, it is 172 in the case of one gas chromatograph.

As another function, the sampling pump 6 increases the pressure of the sample gas supplied to the automatic sampling device 26;
Suppressing pressure fluctuations during sampling due to the pressure difference between sample gas and carrier gas, gas chromatography 15a
, 15b from being impaired.

(Example) An example of the present invention will be described below with reference to FIG.

In FIG. 1, a pipe 27 connected to the upstream system piping of the activated carbon rare gas holding up tower 1 is connected to the clipping supply device 10 of the activated carbon rare gas adsorption capacity testing device 28 via a valve 11. A regulating valve 11 is provided in the middle.

On the other hand, activated carbon rare gas hold up tower 1.1...
A pipe 29 branches from each tower outlet pipe and is connected via a valve 5 to a sample gas supply pipe 12 of an activated carbon rare gas adsorption capacity testing device 28. A sampling pump 6 is provided in the middle of the sample gas supply pipe 12, and the downstream end of the sampling gas supply pipe 12 is connected to port A of the six-way switching valve 2.
It is connected to the. Port B of the six-way switching valve 2} is connected to a sample gas discharge pipe 19 and communicates with the downstream system piping of the activated carbon rare gas hold up tower 1. Further, ports C and D of the six-way switching valve 2 are connected to each other via a sample gas meter 22, and port E is connected to the carrier gas supply device 16 via a carrier gas supply pipe 18.
Ports F are each connected to sample gas transfer tubes 20. The sample gas transfer pipe 20 is connected to port a of the four-way switching valve 24, the carrier gas introduction branch pipe 23 is connected to port b, and the gas chromatograph 15 is connected to ports C and d, respectively.
a and 15b are connected.

The six-way switching valve 2} is driven by a motor or an electromagnetic coil, and as shown by the solid line in FIG.
It is possible to switch between a state in which EF communicates (normal state) and a state in which A-B, C-F, and DE communicate as shown by dotted lines (sampling state).

Like the four-way switching valve 24, it is driven by a motor or an electromagnetic coil, and there is a state in which a-C1b-d communicate as shown by the solid line (state 1), and a-d as shown in the dotted line.
, b and c are in communication (state 2).

The six-way switching valve 2} and the four-way switching valve 24 are respectively switched by the controller 25 as follows.

The switching interval of the six-way switching valve 2} from the normal state to the sampling state is set by the controller 25 (TA/2>
Further, the return from the sampling state to the normal state is also performed by a timer function provided in the controller 25.

The four-way switching valve 24 changes to state 1-state at the same time as the six-way switching valve 2 switches from the normal state to the sampling state! r32
Alternatively, switching from state 2 to state 1 is performed.

The controller 25 is also provided with a mechanism that alternately issues a reset signal to either the gas chromatography 15a or the gas chromatography 15b in conjunction with the switching of the six-way switching valve 2 to the sampling state.

This controller 25 can be configured by a combination of a timer, a switch, and a relay mechanism, or a combination of a timer and an electric sequence circuit, but a programmable controller using a microprocessor or the like is also suitable.

Next, the operation of the embodiment will be explained.

Activated carbon type rare gas with air flowing: 1 - Open valve 4 in the upstream system piping of Rudoup tower 1 and inject non-radioactive Kr in pulse form from krypton supply device 10 through pipe 27 for a fixed period of time, for example, 5 minutes. do.

The flow rate of Kr is adjusted to a constant flow rate by a regulating valve 11. K
Since the system side is operated at a negative pressure of about 1100 nIl1 g, the injection of r can be easily performed by using a container capable of maintaining an appropriate pressure in the krypton supply device 10, such as a cylinder equipped with a regulator.

The injected gas is diluted and transported by the air flowing through the system, and then the activated carbon rare gas holding up tower 1.1...
・The time distribution of the concentration is expanded and guided downstream, but the gas passing through each group is sampled from the pipe 29 by sequentially opening valves 5.5 and 5 as the gas passes through. The sample gas is guided to the sample gas supply pipe 12 by the pump 6, but at this time, the pressure is increased to above atmospheric pressure by the sampling pump 6, and the sample gas is sent to port A of the six-way switching valve 2.

When the six-way switching valve 2} is in the normal state, the sampling gas flows through the path A-D→22→C-B, cleans the inside of the sample gas meter 22, replaces the gas, and is discharged from the sampling gas exhaust pipe 19. Ru.

On the other hand, the carrier gas is supplied from the carrier gas supply device 16 to the carrier gas supply pipe 18 and the port E of the six-way switching valve 2}, and is sent to the sample gas transfer pipe 20 via the path E→F, and then to the port of the four-way switching valve 24. supplied to a. When the four-way switching valve 24 is in state ii, the gas is discharged to the exhaust pipe 19 through the gas chromatography 15a along route a-0.

At the same time, the carrier gas is supplied from the carrier gas supply branch pipe 23 to port b of the four-way switching valve 24, and from b→d
The exhaust pipe 1 passes through the gas chromatography 15b along the route of
It is discharged at 9.

From this state, when a switching signal is sent to the six-way switching valve 2} every time set in the controller 25, the six-way switching valve 2}
is in the sampling state, and the sample gas is 12→A-
The flow bypasses the sample gas quantifier 22 on the route D→19, and a fixed amount of sample gas is sampled in the sample gas quantifier 22, which is then passed through 18-E-
It is carried to the four-way switching valve 24 by the carrier gas flowing along the path D→22→CF→20.

The four-way switching valve 24 simultaneously switches the six-way switching valve 2
! Switched from AI to state 2, a-+d-15b
The gas is transported to the gas chromatograph 15b via the route , and simultaneously analyzed by the gas chromatograph 15b which is reset by a signal from the controller 25.

On the other hand, the carrier gas flows through the gas chromatography 15a along the path 23→b→C→15a.

The return from the sampling state to the normal state is performed after a certain period of time has elapsed using the timer of the controller 25, and this sampling time varies depending on the capacity of the sample gas meter 22 and the carrier gas flow rate, but in general gas chroma!
・For graphics, a sample amount of several degrees Celsius is sufficient, and approximately one minute is appropriate.

After returning to normal state, the carrier gas is 18-E→F→
Gas chromatography 1 along the route 20→a→b→15b
When the next switching signal is sent from the controller 25 to the six-way switching valve 2, the sample gas in the column is guided to the detection section and the concentration analysis is performed. The gas is subjected to gas chromatography 1 using Chiyariya gas along the route 18 → E-D → 22 → C → F-+ a-(-+l).
5a, and K';d degree analysis is performed.

On the other hand, the carrier gas flows through the gas chromatography 15b along the path 23→bd, and analysis continues.

By continuously repeating the above series of operations, 2
One cycle of sample gas injection, analysis, and reset (time is TA) is TA/2.
This is repeated alternately with a time difference of .

Therefore, while securing the time necessary for one analysis for one gas chromatography unit, the sampling interval can be reduced to T.
A/2, that is, 172 times compared to when one gas chromatography unit is used.

Although FIG. 1 shows an example in which two gas chromatographs are installed, three or four gas chromatographs can be installed by using a six-way switching valve or a multi-way switching valve such as a six-way switching valve instead of the four-way switching valve 24. Alternatively, more gas chromatographs can be used in one automatic sampling device, further shortening the sampling interval at low cost.

When using 0 gas chromatographs, theoretically,
The sampling interval is T^/n, that is, 1/ in the case of one device.
It is possible to make n. As mentioned above, the Kr peak detected by gas chromatography analysis is fitted to a Gaussian distribution, the Kr concentration distribution is determined, the time h at which the Kr concentration reaches its peak is determined, and the activated carbon concentration is determined by equation [I]. The adsorption ability is evaluated, but data from about 10 points is required for accuracy.

The retention time of each gas varies depending on the length of the gas chromatography column, adsorbent, and carrier gas flow rate, but in general, TK1 = 9 minutes, TK 2 = 10 minutes,
Tc1=20 minutes, Tc2=about 22 minutes6, so 2
In the case of single-stage gas chromatography, the sampling interval is about 12 minutes.

On the other hand, the width of the Krfi degree distribution at the outlet of each unit of the activated carbon rare gas holding up tower in the -fi BWR atomic coupler is approximately 3 hours at the first tower exit and 10 hours at the final tower exit, so the two gas In the case of chromatography, at least 10 data points can be obtained from each column.

Furthermore, in a type in which a large number of smaller activated carbon rare gas hold up towers are installed, the width of the Kr concentration distribution is smaller than the above value. In this case, in the case of two gas chromatographs, the number of data points may be unstable. In such a case, three or four gas chromatographs may be used to further shorten the sampling time.

[Effects of the Invention] According to the activated carbon rare gas adsorption capacity test device according to the present invention, the sampling interval can be shortened, and automation is possible due to the simple design and configuration of the sampling section.

Therefore, it is possible to provide an activated carbon rare gas adsorption capacity test device using non-radioactive krypton that has improved test accuracy, is low cost, has high operability, and is highly reliable.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing an embodiment of the activated carbon rare gas adsorption capacity test @ device according to the present invention, Fig. 2 is a system diagram showing an activated carbon rare gas adsorption capacity test device using conventional radioactive rare gas, 3
The figure is a system diagram showing a conventional activated carbon rare gas adsorption capacity test device using non-radioactive rare gas, and FIGS. 4 and 5 are characteristic diagrams showing examples of chromatograms obtained by gas chromatography. 1...Activated carbon rare gas holding up tower 2.9...Activated carbon rare gas adsorption capacity test device 3.16...
・Carrier gas supply device 4.5.13.17... Valve 6... Sampling pump 7...
...Electric layer box 8...Radiation measuring device 10...Krypton supply device 11...
...Adjustment valve 12 ...Sample gas supply pipe 14 ...
......Sampler 15......Gas chromatography 18...
......Carrier gas introduction pipe 19...
...Sample gas discharge pipe 20...Sample gas transfer pipe 2}...Six-way switching valve 22...Sample gas quantitative meter 23・・・
...Carrier gas introduction branch pipe 24...
...Multi-way switching valve 25...Controller 26...Automatic sampling device 27...
...Administrative applicant Toshiba Corporation Representative Patent attorney Satoshi Suyama - Figure 1

Claims (2)

[Claims] (1) In order to test the rare gas adsorption ability of the activated carbon filled in the activated carbon rare gas hold-up tower, there is an air supply means on the upstream side, a non-radioactive krypton supply means on the inlet side of the activated carbon rare gas hold-up tower, and an activated carbon type rare gas hold-up tower. On the outlet side of the rare gas hold-up column, there is a gas chromatograph as a means for measuring the concentration of rare gas, a carrier gas supply device as a means for transferring sample gas to the gas chromatography, and a sampling device for supplying sample gas to the gas chromatography in a batch manner. Activated carbon rare gas adsorption capacity test device characterized in that the sampling device is provided with a switching mechanism, and one sampling mechanism controls the gas amount and supply interval of sample gas to a plurality of gas chromatographs. Rare gas adsorption capacity test device. (2) The activated carbon rare gas adsorption capacity test device according to claim 1, wherein the switching mechanism is a multi-way switching valve having {(number of gas chromatographs)×2+2} ports.