JPH112552A - Flow measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a discharge valve so as to miniaturize a flow rate measuring device and simplify control mechanism. SOLUTION: A flow rate measuring device for measuring the flow rate of a liquid sample by detecting the supply of the liquid sample in the quantity corresponding to known volume within a given time is provided with a measuring tube 11 supplied with the liquid sample from the upper end, a connecting tube 14 connected to the lower end of the measuring tube 11, a discharge tube 15 connected to the upper end of the connecting tube 14, and level gauges 12, 13 fitted to the measuring tube 11 so as to detect the liquid level of the liquid sample. A connection part between the connecting tube 14 and the discharge tube 15 is arranged in a higher position than the level gauge 13 positioned higher than the level gauge 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the flow rate of a liquid sample used in a wet gas analyzer or the like.

[0002]

2. Description of the Related Art FIG. 6 schematically shows a conventional flow rate measuring device for measuring the flow rate of a liquid sample (absorbing liquid) having absorbed a gas. In the figure, 101 is a measuring tube provided in a flow path of a liquid sample to be measured, and 102 is a measuring tube 1
Reference numeral 103 denotes a level meter for detecting the sample liquid level below the measuring tube 101, reference numeral 103 denotes a level meter for detecting the sample liquid level above the measuring tube 101,
4 is a discharge valve arranged below the level meter 102, 105
Is a controller that calculates and measures the flow rate of the liquid sample based on the output signals of the level meters 102 and 103, and controls the opening of the discharge valve 104 to discharge the liquid sample after the flow rate measurement. In addition, as the level meters 102 and 103, for example, the liquid level of the sample is optically detected based on the refractive index of light.
A system that sends this to the outside as an electric signal is used.

[0003] The operation of the above prior art will be described first.
The liquid sample is supplied into the measuring pipe 101 with the discharge valve 104 closed, and the liquid level of the sample is detected by the level meter 102 at the low position. Thereafter, the liquid level in the measuring tube 101 gradually rises, and the level meter 103 at the high position detects the sample liquid level. During this time, the controller measures the time Δt until the sample liquid level reaches the level meter 103 at the low position from the level meter 102 at the high position. On the other hand, since the volume V of the tube including the measuring tube 101 between the level meter 102 and the level meter 103 is known, the flow rate of the liquid sample can be obtained by dividing the volume V by the time Δt. After measuring the flow rate in this manner, the controller 10 prepares for the next measurement.
5, the discharge valve 104 is opened, and the liquid sample is discharged.

[0004]

However, since the above-mentioned prior art requires the discharge valve 104, the size of the apparatus tends to be large, and when the discharge valve 104 fails, the flow rate is repeatedly determined. There were inconveniences that could not be measured. Further, since the controller 105 has a function of controlling the opening and closing of the discharge valve 104, the circuit configuration is complicated. Accordingly, an object of the present invention is to provide a flow rate measuring device capable of performing a series of operations of measuring and discharging a flow rate of a liquid sample without using a discharge valve.

[0005]

According to a first aspect of the present invention, a liquid sample is connected to a first tube supplied from an upper end and a lower end of the first tube. A second pipe, a discharge pipe connected to an upper end of the second pipe, and at least one level meter attached to the first or second pipe for detecting a liquid level of the liquid sample. And a connecting portion between the second pipe and the discharge pipe is arranged at a higher position than the highest one of the level meters. Here, the first or second tube acts as a measuring tube, and by detecting the liquid level of the liquid sample accumulating in the measuring tube with a level meter, the amount of the liquid sample corresponding to a known volume is obtained. Measure the accumulation time and measure the flow rate.
When the liquid surface of the liquid sample reaching the connection between the second tube and the discharge tube becomes lower than the liquid surface in the first tube, the liquid sample is discharged from the connection by the so-called siphon principle. The liquid sample in the measuring tube is automatically discharged from the discharge tube due to the negative pressure generated at the time of the discharge in the tube direction.

According to a second aspect of the present invention, there is provided the first tube to which the liquid sample is supplied from the upper end, and the second and third tubes connected to the lower end of the first tube. , A discharge pipe connected to the upper end of the third pipe, and at least one level meter attached to the second or third pipe for detecting the liquid level of the liquid sample, The connecting portion between the body and the discharge pipe is arranged at a higher position than the highest one of the level meters. Here, the second or third pipe acts as a measuring pipe, measures the flow rate according to the same principle as in the first aspect of the present invention, and reaches the connecting portion between the third pipe and the discharge pipe. When the liquid level of the liquid sample becomes lower than the liquid level in the first tube, the liquid sample is automatically discharged from the discharge pipe by the siphon principle.

According to a third aspect of the present invention, in the flow rate measuring device according to the second aspect, when the liquid sample contains gas, the gas is sucked from the upper end of the second tube. Gas-liquid separation is performed smoothly. For this reason, since there is no possibility that the formation of the negative pressure is hindered by the bubbles, the discharge of the liquid sample is facilitated. Further, measurement errors caused by air bubbles mixed into the level meter can be avoided.

Further, by making the pressure at the upper end of the first tube equal to the outlet pressure of the discharge tube, the liquid sample can be smoothly discharged.

Further, as set forth in claim 5, the thickness of the vicinity of the connecting portion between the discharge pipe and the preceding pipe is formed smaller than the thickness of the preceding pipe of the connecting section. This makes it difficult for air to enter the vicinity of the connecting portion when the liquid sample is discharged, thereby facilitating the formation of a negative pressure and further facilitating the discharge of the liquid sample.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention.
It is a schematic structure figure showing an embodiment. In FIG.
11 is a measuring tube as a first tube into which the liquid sample flows,
Reference numeral 14 denotes a connecting pipe as a second pipe connected to the lower end of the measuring pipe 11 and folded back by 180 degrees, and 15 denotes a discharge pipe connected to the upper end of the connecting pipe 14 and turned back by 180 degrees. The measuring tube 11 is a measuring tube main body 1 to which a liquid sample is supplied.
1A, a level meter 12 for detecting a sample liquid level below the measuring pipe main body 11A, and a level meter 13 for detecting a sample liquid level above the measuring pipe main body 11A. Level meter 12,
Numeral 13 denotes a sensor for detecting the liquid surface of the sample by optical means as in FIG. 6, and is connected to arithmetic means (not shown) corresponding to a conventional controller. Also, the connecting pipe 14
The connecting portion between the and the discharge pipe 15 is arranged at a position higher than the level meter 13 at the high position.

Next, the operation of this embodiment will be described. When the liquid sample is supplied to the measuring tube 11, the sample accumulates from the connection between the measuring tube 11 and the connecting tube 14, and the sample liquid level reaches the measuring position of the level meter 12 at a low position. The level meter 12 detects this liquid level and sends a signal to the calculating means. Then, the liquid level in the measuring pipe main body 11A is changed to the connecting pipe 14.
It rises with the liquid level in the inside and reaches the measurement position of the level meter 13 at a high position. The level meter 13 detects this liquid level and sends a signal to the calculating means in the same manner as described above. The calculating means measures the time Δt until the sample liquid level reaches the level meter 13 at the high position from the level meter 12 at the low position, based on the liquid level detection signals from the level meters 12 and 13. In addition, level meter 1
Since the volume V of the tube body including the measuring tube main body 11A between the tubes 2 and 13 is known, the flow rate of the liquid sample can be obtained by dividing the volume V by the time Δt. Note that even if the flow velocity of the liquid sample fluctuates, its cycle is assumed to be sufficiently longer than the flow measurement cycle.

Thereafter, when the sample liquid level in the measuring pipe 11 further rises above the level L1 shown in FIG. 1, the liquid level in the connecting pipe 14 becomes lower than the level L1 through the connection with the discharge pipe 15. Therefore, the pressure balance is lost due to the so-called siphon principle, and the liquid sample in the connecting pipe 14 and the measuring pipe main body 11A is discharged from the discharge pipe 15. Then, the liquid sample starts to accumulate inside the measuring pipe 11 and the connecting pipe 14 again. After the flow rate is measured in the same manner as described above, the liquid sample is automatically discharged from the discharge pipe 15 when the liquid level reaches the level L1. You. By repeating this operation, the flow rate measurement and discharge of the liquid sample can be performed periodically.
The sample can be automatically discharged without using a conventional discharge valve.

Note that it is not always necessary to arrange two level meters, and for example, a structure in which only the high level meter 13 is arranged may be used. That is, when using only the level meter 13 at the high position, the measuring pipe 11 and the connecting pipe 14 start supplying the liquid sample from an empty state, and from that point on, the level meter 1 is started.
The time Δt until the liquid surface of the sample is detected is measured by 3. In this case, since the volume V of the measuring pipe 11 and the connecting pipe 14 located below the level meter 13 is known, the flow rate of the sample is obtained from the volume V and the time Δt.
However, when only one level meter is used, the volume of the connecting portion between the measuring pipe 11 and the connecting pipe 14 is also used for the flow rate measurement. Becomes an error with respect to the volume V by that much,
If possible, two level gauges 12 and 13 at the high position and the low position
It is desirable to use

FIG. 2 shows a second embodiment of the present invention. In the embodiment of FIG.
In the case where the liquid sample descends along the tube wall of the measuring tube 11, there is a risk that the level meters 12 and 13 may erroneously recognize the liquid sample as a liquid surface. Therefore, in the second embodiment, the position of the measuring tube 11 is changed so as not to make an erroneous detection due to a sample traveling down the tube wall.

That is, in FIG. 2, reference numeral 16 denotes an inflow pipe into which the liquid sample flows, 11 denotes a measuring pipe connected to the lower end of the inflow pipe 16 and is turned back by 180 degrees, and 15 denotes an upper end of the measuring pipe 11. It is a discharge pipe folded 180 degrees. The measuring pipe 11 is provided with a measuring pipe main body 11A, a low level meter 12 and a high level meter 13 in the same manner as described above, and a connecting portion between the measuring pipe 11 and the discharge pipe 15 is provided at a high position. It is arranged at a position higher than the level meter 13.

In this embodiment, when a liquid sample is supplied to the inflow tube 16, the sample accumulates from the connection between the inflow tube 16 and the measuring tube 11, and the liquid level in both tubes 16, 11 gradually increases. Going up. The flow rate of the sample remains unchanged in that it is determined by the time required for the liquid surface to reach the position of the level meter 13 from the position of the level meter 12 in the measuring tube 11 and the volume between them, but in this embodiment, Since the sample does not travel down the wall of the measuring tube 11, there is no fear that the level meters 12 and 13 mistakenly detect the sample adhering to the tube wall as the liquid level as described above. Therefore, the measurement accuracy of the flow rate can be improved as compared with the first embodiment.

When the liquid surface of the liquid sample reaches the level L1, the liquid sample is discharged from the discharge pipe 15 as in the first embodiment. In this embodiment, as in the first embodiment, one level meter may be used, but in this case, if all of the sample remains at the connection between the inflow pipe 16 and the measuring pipe 11 without being discharged, That amount can cause measurement errors.

Next, an embodiment of the invention described in claim 2 will be described. FIG. 3 is a schematic configuration diagram of this embodiment, and corresponds to a structure in which the inflow pipe 16 in FIG. 2 is connected to the connection between the measurement pipe 11 and the connection pipe 14 in FIG. That is, the flow measuring device shown in FIG. 3 includes an inflow pipe 16 as a first pipe, a measuring pipe 11 as a second pipe connected to a lower end thereof and parallel to the inflow pipe 16, A connecting pipe 14 as a third pipe body connected to the section and parallel to the measuring pipe 11, and connected to the upper end of the connecting pipe 14, 18.
And a discharge pipe 15 turned back at 0 degrees. Here, the measuring pipe 11, the connecting pipe 14, and the inflow pipe 16 do not necessarily need to be connected at the same place as shown in FIG.
It is also possible to connect the connecting pipe 14 to the connecting section between the measuring pipe 11 and the measuring pipe 11 via an appropriate pipe, or to connect the inflow pipe 16 to the connecting section between the measuring pipe 11 and the connecting pipe 14 via an appropriate pipe. good. In short, it is sufficient that the lower end of the inflow pipe 16 is directly or indirectly connected to the measuring pipe 11 and the connection pipe 14. In addition, 12,
Reference numeral 13 denotes a level meter arranged above and below the measuring tube main body 11A. 1, the connecting portion between the connecting pipe 14 and the discharge pipe 15 is arranged at a position higher than the level meter 13 at a high position.

Here, the upper end of the measuring pipe 11 is open to the atmosphere or connected to a gas pump (not shown). This is because, for example, in a wet gas analyzer, when measuring the flow rate of a liquid sample in a state where the sample gas is mixed without being absorbed by the absorbing liquid, the gas is removed by suction from the upper end of the measuring tube 11. This is a structure for performing separation. At this time, although omitted in FIG. 3, by connecting the inflow pipe 16 and the measuring pipe 11 at a position higher than the level L1 of the connection portion between the connection pipe 14 and the discharge pipe 15,
Bubbles in the liquid sample can be prevented from entering the measuring tube 11A.

Also in this embodiment, the flow rate of the sample can be measured by the level meters 12 and 13 on the same principle as in the above-described embodiment. After the flow rate measurement, when the liquid level in the inflow pipe 16 and the measuring pipe 11 exceeds the level L1, the sample in the connection pipe 14 is discharged to the outside via the discharge pipe 15, and then the inflow pipe 16 The sample in the measuring tube 11 is discharged to the outside via the connecting tube 14 and the discharging tube 15.

According to this embodiment, since the sample inflow pipe 16 and the measuring pipe 11 are separated, erroneous detection of the liquid level by the level meters 12 and 13 can be prevented as in the embodiment of FIG. The effect can be obtained, and a path for sucking and removing gas from the liquid sample can be secured at the upper end of the measuring tube 11. Of course, also in this embodiment, the flow rate can be measured by one level meter in principle.

Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 4 shows a structure that embodies the configuration shown in FIG. 3 and further enables separation of gas mixed in the liquid sample. In FIG. 4, an inflow pipe 1 is provided on a substrate 171.
61, the measuring pipe 111, the connecting pipe 141, and the discharging pipe 15
1 is integrally formed, and a glass tube having a connecting pipe 113 connecting the measuring pipe 111 and the inflow pipe 161 and an overflow pipe 114 communicating with the inflow pipe 161 is fixed. In addition, 111A is a measuring pipe main body, 1
Reference numerals 21 and 131 denote level meters at a low position and a high position, respectively.
12 is a gas suction pipe connected to the upper end of the measuring pipe 111,
Reference numeral 115 denotes a sample supply pipe. Here, the gas suction pipe 112
Is connected to a gas pump (not shown), and the overflow pipe 114 and the discharge pipe 151 communicate with the inside of the same drain vessel (not shown) and are kept at the same pressure. Reference numeral 174 denotes a substrate on which the head amplifiers of the level meters 121 and 131 are mounted, and 172 and 173 light L to indicate when the level meters 121 and 131 detect the liquid level.
ED.

The inflow pipe 161 whose upper end is connected by the connecting pipe 113 and the measuring pipe 111 are connected at the lower end. The lower end of FIG.
The distal end of the connecting pipe 141 juxtaposed on the front side of FIG.
As shown in FIG. 4 (B), it goes around the back side so as to be orthogonal to the plane formed by the inflow pipe 161 and the measuring pipe 111, and is connected to the discharge pipe 151. In addition, the pipe wall is formed to be thick from the upper end of the connecting pipe 141 to almost the entire length of the discharge pipe 151. In other words, in this portion, a small-diameter portion 142 in which the inner diameter of the pipe is smaller than other portions is provided. Has formed. The provision of the small-diameter portion 142 makes it difficult for air to enter into the liquid sample when the liquid sample is discharged from the discharge tube 151 by the action of the siphon. Is smoothly discharged.

Next, FIG. 5 shows an overall configuration of a gas analyzer using the flow rate measuring device of FIG. 4, for example, an analysis for measuring the concentration of hydrogen chloride in exhaust gas passing through a flue 201 of a refuse incinerator. It is an example of a total. In FIG. 5, reference numeral 202 denotes a heating conduit for taking in exhaust gas, 203 denotes a gas absorbing section for contacting and absorbing the exhaust gas with the absorbing liquid sent from the absorbing liquid tank 204 by a pump 205, and 206 denotes a measuring cell having a chloride ion electrode as a sensor. , 207 are flow rate measuring devices shown in FIG. 4 (which also have a function as a gas-liquid separator),
208, a trap for storing the liquid sample discharged from the flow rate measuring device 207; 209, a dehumidifier for dehumidifying gas sucked from the gas suction pipe 112 of the flow rate measuring device 207;
210 is a gas pump for sucking this gas, and 211 is a pump for discharging the liquid sample in the trap 208. In the drawing, pumps 205 and 211 connected by broken lines
Are linked, and the amount of liquid sent from the pump 211 is larger than the amount of liquid sent from the pump 205 because water in exhaust gas is also discharged in addition to the absorbing liquid. In this embodiment, the purpose of gas-liquid separation and discharge of the absorbing liquid having absorbed the gas is to prevent formation of a negative pressure from being hindered by mixing of bubbles into the absorbing liquid. This gas-liquid separation also makes it possible to separately measure the flow rate of the exhaust gas and the flow rate of the absorbing liquid that come into contact with the absorbing liquid.

The overall operation of the above gas analyzer will be described. The absorbing solution having absorbed the exhaust gas in the gas absorbing section 203 is sent as a liquid sample to the measuring cell 206, and the chloride ion concentration is measured by the chloride ion electrode. Is done. Then, a value obtained by converting the chloride ion concentration into a hydrogen chloride concentration is indicated and recorded. After the measurement, the liquid sample is supplied to the flow measuring device 207 with the gas not absorbed in the absorbing liquid mixed therein, and the flow measuring and discharging operations are repeated at a predetermined cycle. The gas mixed in the liquid sample is supplied to the dehumidifier 2
The liquid sample sucked and removed by the gas pump 210 via the pipe 09 and degassed is sent from the discharge pipe 151 to the trap 208, and then discharged by the pump 211 together with the moisture dehumidified by the dehumidifier 209. As shown in FIG. 5, the overflow pipe 114 and the discharge pipe 151 of the flow rate measuring device 207 communicate with each other via the internal space of the trap 208 and are kept at the same pressure. Will be smoothly discharged to the trap 208.

[0026]

As described above, according to the first or second aspect of the present invention, the siphon is constituted by the second or third pipe and the discharge pipe. This eliminates the need to provide a device, thereby reducing the size of the device and eliminating accidents such as failure of the discharge valve and liquid leakage. In addition, since a control mechanism for the discharge valve is not required, the circuit can be simplified.

Further, according to the third aspect of the present invention, when the flow rate measuring device is applied to a gas analyzer, gas-liquid separation can be performed.
It becomes possible to individually measure the flow rates of the gas and the absorbing liquid, and to collect the absorbing liquid. Further, according to the invention described in claim 4 or 5, it is possible to smoothly discharge all the liquid sample after the flow rate measurement, which contributes to improvement of measurement accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of the invention described in claim 1;

FIG. 2 is a schematic configuration diagram showing a second embodiment of the invention described in claim 1;

FIG. 3 is a schematic configuration diagram showing an embodiment of the invention described in claim 2;

FIG. 4 is a front view (FIG. 4A) and a side view (FIG. 4B) of a main part showing an embodiment of the invention described in claim 2;

5 is an overall configuration diagram of a gas analyzer to which the embodiment of FIG. 4 is applied.

FIG. 6 is a schematic configuration diagram showing a conventional technique.

[Explanation of symbols]

 11, 111 Measuring tube 11A, 111A Measuring tube main body 12, 13, 121, 131 Level meter 14, 141 Connecting tube 15, 151 Discharge tube 16, 161 Inflow tube 112 Gas suction tube 113 Communication tube 114 Overflow tube 115 Sample supply tube 142 Thin portion 171, 174 Substrate 172, 173 LED 201 Flue 202 Heating conduit 203 Gas absorption unit 204 Absorbent tank 205, 211 Pump 206 Measurement cell 207 Flow rate measurement device (gas-liquid separation device) 208 Trap 209 Dehumidifier 210 Gas pump

Claims (5)

[Claims] 1. A flow rate measuring apparatus for detecting a supply of a liquid sample in an amount corresponding to a known volume within a predetermined time and measuring a flow rate of the liquid sample, wherein the liquid sample is supplied from an upper end portion. A first pipe, a second pipe connected to a lower end of the first pipe, a discharge pipe connected to an upper end of the second pipe, and a first or second pipe. At least one level gauge for detecting a liquid level of the liquid sample, wherein a connection portion between a second pipe and the discharge pipe is higher than the highest one of the level meters. A flow measuring device, wherein the flow measuring device is arranged at a position. 2. A flow rate measuring apparatus for measuring the flow rate of a liquid sample by detecting that an amount of a liquid sample corresponding to a known volume has been supplied within a predetermined time, wherein the liquid sample is supplied from an upper end portion. A second pipe, a second pipe, a third pipe connected to a lower end of the first pipe, a discharge pipe connected to an upper end of the third pipe, and a second or third pipe. At least one level meter attached to the tube for detecting the liquid level of the liquid sample, wherein a connection between the third tube and the discharge pipe is provided at the highest position of the level meters. A flow measurement device characterized by being arranged at a higher position than the above. 3. The flow rate measuring device according to claim 2, wherein the liquid sample contains a third gas when the liquid sample contains gas.
Connecting the first pipe and the second pipe at a position higher than the connection between the pipe and the discharge pipe, and sucking gas from the upper end of the second pipe. Flow measurement device. 4. The flow measuring device according to claim 1, wherein the pressure at the upper end of the first pipe is equal to the pressure at the outlet of the discharge pipe. 5. The flow rate measuring device according to claim 1, wherein the thickness near the connecting portion between the discharge pipe and the preceding pipe is
A flow measuring device characterized in that it is formed to be thinner than the wall thickness of the tube at the preceding stage of the connecting portion.