JP3097820B2 - How to clean the flowing ammeter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow ammeter for controlling the amount of an ionic coagulant added in water treatment and / or sludge treatment, and more particularly to the structure described in claim 1 or 2. The present invention relates to a method for cleaning a flowing ammeter having a characteristic.

[0002]

2. Description of the Related Art Coagulation processes in water treatment and sludge treatment (for example, polymer coagulation in a belt press or centrifugal dehydrator,
Alternatively, an ionic coagulant is frequently used in the coagulation and sedimentation step in a water purification plant, and a flow ammeter measurement value (hereinafter referred to as a flow current value) is used as an index as a method of controlling the injection amount, and the value becomes a predetermined value. A method for controlling the injection amount has been proposed ( Japanese Patent Laid-Open No. 4-83600 and others). Compared with the solid (or turbidity) proportional method which has been widely used so far, this method can control the coagulant injection amount to the optimum amount for the properties of the sample and does not cause excess or deficiency of the coagulant. This is an excellent method having effects such as always maintaining the coagulation process well and preventing waste of the coagulant.

However, if the flow ammeter is used continuously for a long period of time, the control target value of the flow ammeter is set to
Even when the "predetermined value such as near zero" claimed in the description of -193801 was used, a phenomenon that the addition of the ionic coagulant was not always in a satisfactory state occurred. As a result of investigating the cause, it was found that some contamination occurred in the probe portion such as the piston, the inner surface of the cylindrical container or the electrode of the flow ammeter, and the zero point or the sensitivity was changed.

Conventionally, in order to prevent this type of contamination, a cleaning fluid (usually, industrial water or tap water) is passed directly to a sample chamber or a probe at an appropriate time interval, and the probe is moved up and down by a piston of a flow ammeter. It has been clarified that the inside should be stirred and washed (Japanese Patent Application No. 7-53680). If the contamination is significant and normal cleaning is not effective, it is necessary to disassemble the probe part and immerse and clean it in an oxidizing agent solution such as acid / alkali or sodium hypochlorite. At the time of this cleaning, the manufacturer strictly commented that the disassembled probe should not be handled roughly and that gas should not be allowed to flow through the probe in order to avoid wear due to direct contact between the piston and the inner wall of the cylindrical container. ing.

[0005]

However, in the current situation of the washing of the flowing ammeter as described above, it is necessary to frequently supply the washing liquid, and during that time, the operation of the dehydrator and the like must be stopped. If the performance is not restored sufficiently, the coagulation / dehydration process is not stable. Disassembly of the probe is extremely troublesome. Therefore, there is a demand for a cleaning method capable of maintaining the performance of the flowing ammeter by effective cleaning.

[0006]

The present invention was devised as a result of studying various cleaning methods as means for solving the above problems. That is, (1) a cylindrical container 11 for holding the fluid A to be measured inside, and a pair of electrodes 12 disposed in the cylindrical container 11 so as to be spaced apart from each other in the longitudinal direction.
A and 12B, and a piston 14 that reciprocates in its length direction inside the cylindrical container 11 to cause a fluid A to be measured to flow to generate a flowing current between the pair of electrodes 12A and 12B, One end is directly attached to a position that does not affect the measurement result of the cylindrical container 11, and a supply pipe 11A that supplies the fluid A to be measured to the inside of the cylindrical container 11, and the measurement result of the cylindrical container One end is directly attached to a position that does not affect the flow, a discharge pipe 11B that discharges the fluid A to be measured from the inside of the cylindrical container 11 to the outside, and one end is directly attached to the cylindrical container 11, In a flow ammeter 10 having a cleaning medium supply pipe 16 for supplying a cleaning medium to the inside of the cylindrical container 11, the cleaning medium and the cleaning medium are continuously or intermittently reciprocated by a piston 14. The method of cleaning streaming current meter and introducing the liquid C1 and gas C2 Te. Or
(2) The cylindrical container 21 for measuring a flowing current is accommodated in the internal space of the external container 28, and the cylindrical container 21 and the external container 28 are connected by a supply pipe and a discharge pipe, and the measurement in the cylindrical container is performed. A cleaning medium supply pipe for directly supplying a cleaning medium to one end of the cylindrical container 21 in the flow ammeter 20 in which the fluid A is retained by the external container 28 via the supply pipe 26A and the discharge pipe 26B. 26
Is provided to clean the cylindrical container 21 with the external container 28.
The method for cleaning a flowing ammeter according to the above (1), wherein the method is carried out without any intervention.

A liquid and a gas are used together as a cleaning medium, and a gas-liquid multiphase flow containing fine bubbles is generated between the piston and the cylindrical container under the vertical movement of the piston, thereby performing extremely effective cleaning. is there. In the presence of liquid and gas,
When the gas-liquid multi-phase flow is generated extremely efficiently, the cleaning is completed by a half-reciprocal (forward or backward) vertical movement of the piston. The vertical movement of the piston is preferably performed continuously even during the cleaning, but the movement speed and the like need not necessarily be the same as during the measurement, and may be intermittent. As described above, in the past, it was supposed that gas was not allowed to flow in the probe when cleaning the flowing ammeter, but even if the cleaning method of the present invention was carried out, there was no hindrance to the measurement of the flowing current after cleaning. There is no problem at all even if the flowing ammeter is used for a considerably long time while adopting the cleaning method described above.

[0008]

According to the present invention, with decreasing viscosity of the fluid due to the formation of the gas-liquid mixed flow, the flow rate increases and uniformity diffusion of fluid flowing between the piston inner wall Ji live, effective cleaning results. Furthermore, generation and destruction of fine bubbles from the influent gas by the pressure variation caused by the vertical movement of the piston Ri Do that occurs violently, in which further increase the washing effect.

FIG. 1 is a sectional view showing the entire configuration of a flowing ammeter 10 according to one embodiment of the present invention. The flow ammeter 10 shown in FIG. 1 includes a cylindrical container 11, electrodes 12A and 12B, a driving device 13, a piston 14, an ammeter 15, and a connection line 15.
a, 15b, cleaning medium supply pipe 16, on-off valve 17a,
17b and 17c. Measurement sample A is supplied from supply pipe 1
1A, and is discharged from the discharge pipe 11B. At the time of cleaning, a cleaning liquid C1 and a gas C2, which are cleaning media, are used.
Is appropriately sent from the lower part of the cylindrical container 11.

The phenomena occurring in the flowing ammeter are as follows. In FIG. 1, the measurement sample A flows into the gap between the cylindrical container 11 and the piston 14 by the vertical movement of the piston,
The particles in the sample A are adsorbed on the surface of the cylindrical container 11 or the piston 14. Due to the flow of the fluid flowing through the gap between the cylindrical container 11 and the piston 14, charges on the surface of the adsorbed particles are transferred, and a streaming potential is generated between the electrodes. Due to the long-term inflow of the sample, the contaminated components in the sample remain adsorbed on the surfaces of the cylindrical container 11 and the piston 14, causing a change in the gap distance, a change in the charge state of the surface, etc., and the contamination proceeds. Then, the generated streaming potential measurement value changes. When this situation is reached, the on-off valves 17a, 17b, 17
c is opened and closed, and the cleaning medium flows into the cylindrical container 11 from the cleaning medium supply pipe 16. The flowing cleaning medium rises in the gap between the cylindrical container 11 and the piston 14. During that time, the cleaning medium cleans the cylindrical container 11, the piston 14, and the electrodes 12A and 12B by the behavior described above, and is discharged from the cleaning medium 11B.

The method for introducing the cleaning gas is arbitrary. For example, in one example, the on-off valves 17a, 17b, and 17c are simultaneously opened to supply the cleaning medium (liquid and gas) to the cleaning medium supply pipe 1.
6 and simultaneously supplied into the probe as a gas-liquid multiphase fluid. As another example, a cleaning medium supply pipe 16 may be separately provided to separately supply a cleaning liquid and a gas. At this time, a thin nozzle may be provided as a supply pipe. Most preferably, the gas is used simultaneously with the liquid. It is also good to ventilate for a short time after the liquid is washed for a predetermined time. It is necessary to be careful as it leads.

[0012] Repeated cleaning is effective. The gas-liquid multi-phase flow and the liquid washing are repeated for a short time (for example, 5 times every 5 seconds), and finally, the liquid washing is continued for 10 seconds, and then the washing process (total 1 minute) is completed and the process proceeds to the measurement process. Good.
The liquid preferably used in the present invention is water, and the gas is air. It is even better to rinse with water only after the combined use of water and air. In this way, rinsing with only water after the combined use of water and air can completely eliminate the concern that fine bubbles remain.

FIG. 2 is a sectional view showing the overall configuration of a flowing ammeter 20 according to another embodiment of the present invention. A flowing ammeter 20 shown in FIG. 2 is a cylindrical inner container 21 for measuring a flowing current.
The measurement sample A flows through the supply pipe 26A via the external container 28, and is discharged from the discharge pipe 26B via the external container 28 to fill the internal container 21. In the cylindrical inner container 21 for measuring the flowing current,
The electrodes 22A and 22B are installed, and the space is filled with the measurement sample A as described above, and the piston 24 immersed therein is driven up and down by an external driving device 23 to move the electrodes 22A and 22B Is measured by the ammeter 25. However, at the time of cleaning, the cleaning liquid C1 and the gas C2, which are cleaning media, are supplied to the on-off valve 27a,
27b and 27c are opened and closed, and the cleaning medium flows into the cylindrical internal container 21 from the cleaning medium supply pipe 26 provided directly at the lower end of the internal container 21. While supplying the cleaning medium in the same manner as for cleaning, the piston 24 is moved up and down to clean the inside. As described above, the method for cleaning a flowing ammeter of the present invention is also effective for a dual-structure flowing ammeter having an outer container and an inner container.

[0014]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 A cationic polymer was added to digested sludge discharged from an municipal sewage treatment plant and dewatered by a centrifugal dehydrator. The separated liquid from the centrifugal dehydrator was used as a flowing ammeter sample. Here, the single-structured flow ammeter shown in FIG. 1 was used. At the time of washing, a washing medium was allowed to flow into the flow ammeter from below the probe via an electromagnetic valve. The opening and closing of the solenoid valve was appropriately set for time. Also, a gas inflow valve is installed in the cleaning medium piping,
Cleaning gas could be flowed in as appropriate.

Tap water and air were used as the cleaning medium, and the time intervals for cleaning were set as follows. That is, after washing with air and water simultaneously was repeated 5 times, water washing was performed for 10 seconds for 5 seconds, and after repeating this 5 times, water washing was performed for 10 seconds. The time required for one washing was 1 minute in total, and this was repeated every predetermined time. FIG. 3 shows the results of recording the change with time of the output of the flow ammeter while keeping the sludge flow rate and the polymer flow rate constant. In the case of no washing (upper stage), the output greatly changed, and in the case of water washing (middle stage), the output greatly changed immediately after washing, and thereafter gradually changed to a saw-like curve as a whole. In the present invention (lower), although the output changes only during cleaning, it returns to the original value after cleaning, indicating that the measured value is stable as a whole. Table 1 shows the results of examining the output stability by changing the water passage time and the washing interval. In the conventional method, the time during which a stable output is obtained is extremely short, and the effectiveness of the present invention has been recognized.

[0017]

[Table 1]

[0018]

The present invention is a method for increasing the detergency of a cleaning fluid by injecting a gas, which has been strictly prohibited until now, into the probe, and using the vertical movement of the liquid, gas and piston together. Micronization of bubbles, uniform dispersion,
The contact (cleaning) area is increased, and an ultrasonic cleaning effect due to the generation and destruction of air bubbles is generated, so that it can be quickly and uniformly washed to every corner, thereby improving the efficiency of cleaning. As a result of the present invention, the sensitivity fluctuation of the flow ammeter can be sufficiently suppressed,
By controlling the flocculant by the flow ammeter, stable operation of the dehydrator is ensured, and the zero / span adjustment of the flow ammeter becomes unnecessary, so that the maintenance and management become easy.

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of a flowing ammeter according to the present invention.

FIG. 2 is a schematic view of another example of the flowing ammeter of the present invention.

FIG. 3 is a curve showing a change with time of the output of a flowing ammeter according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Flowing ammeter 11 Cylindrical container 11A Supply pipe 11B Discharge pipe 12A Electrode 12B Electrode 13 Driving device 14 Piston 15 Ammeter 16 Cleaning medium supply pipe 17a On-off valve 17b On-off valve 17c On-off valve 20 Flowing ammeter 21 Cylindrical inner container 22A Electrode 22B Electrode 23 Drive 24 Piston 25 Ammeter 26 Cleaning medium supply pipe 26A Supply pipe 26B Discharge pipe 27a Open / close valve 27b Open / close valve 27c Open / close valve 28 External container A Measurement sample C1 Cleaning liquid C2 Gas

Continuation of the front page (72) Inventor Ikue Yagishita 11-1 Haneda Asahimachi, Ota-ku, Tokyo Ebara Corporation (56) References JP-A-60-1770757 (JP, A) (JP, U) Japanese Utility Model Showa 59-189153 (JP, U) Japanese Utility Model Showa 55-80738 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 27/38 341 G01N 27 / 26

Claims (2)

(57) [Claims] 1. A cylindrical container 11 for holding a fluid A to be measured therein, a pair of electrodes 12A and 12B disposed in the cylindrical container 11 so as to be spaced apart from each other in a longitudinal direction thereof, Reciprocating in its length direction inside the container 11,
By causing the fluid A to be measured to flow, the pair of electrodes 1
Piston 14 for generating a flowing current between 2A and 12B
A supply pipe 11A having one end directly attached to a position that does not affect the measurement result of the cylindrical container 11 and supplying a fluid A to be measured to the inside of the cylindrical container 11;
One end is directly attached to a position that does not affect the measurement result of the cylindrical container, and the fluid A to be measured is transferred to the cylindrical container 1.
1 and a cleaning medium supply pipe 16 having one end directly attached to the cylindrical container 11 and supplying a cleaning medium to the inside of the cylindrical container 11. A method for cleaning a flowing ammeter, wherein a liquid C1 and a gas C2 are introduced as a cleaning medium in the flowing ammeter 10 while the piston 14 is continuously or intermittently reciprocated. 2. A cylindrical container 21 for measuring a flowing current is accommodated in an internal space of an external container 28, and the cylindrical container 21 and the external container 28 are connected by a supply pipe and a discharge pipe. The supply pipe 26 is used to hold the fluid A to be measured.
A and a cleaning current supply pipe 26 for directly supplying a cleaning medium to the inside of one end of the cylindrical container 21 in the flowing ammeter 20 performed by the external container 28 through the discharge pipe 26B. The method for cleaning a flowing ammeter according to claim 1, wherein the cleaning of the container (21) is performed without passing through the external container (28).