JPS5934964B2 - Electrode type sludge interface meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a pair of detection electrodes is formed from an electrochemically relatively noble metal and a base metal, and the pair of detection electrodes are separated from each other by a predetermined distance. A galvanic battery is formed by placing it in a liquid, and the pair of detection electrodes of this battery are electrically connected by an external circuit to make this battery system a closed circuit battery system, and the voltage of this closed circuit battery system is or detect current,
The present invention relates to an electrode type sludge interface meter that detects a change in the interface between the liquid and the sludge in the liquid from the detected voltage or current.

Figure 1 shows the basic configuration of the electrode type sludge interface meter.

'This electrode type sludge interface meter is known from Japanese Patent Laid-Open No. 71392/1983. In the figure, the cathode electrode 2 is an electrode made of an electrochemically relatively noble metal such as stainless steel, and the anode electrode 3 is an electrode made of a base metal such as iron such as tag tile cast iron. An electrode system 1 consisting of 2 and 3 is immersed in a sedimentation tank 4. Then, when a load resistor 5 is connected externally to form a closed circuit,
Dissolved oxygen is reduced in the stainless steel electrode 2, and iron hydroxide and iron oxide are dissolved in the tag tile cast iron electrode 3 due to dissolution of iron.
In response to these electrochemical reactions, a current path is formed in a closed circuit consisting of the cathode electrode 2, the anode electrode 3, and the load resistor 5, and a voltage drop occurs across the load resistor 5. By the way, this voltage is the effective acid on the electrode surface.
5. Highly dependent on elementary concentration.

That is, for example, the dissolved oxygen concentration in the water 6 of the sedimentation tank 4 reaches 10- from the number 1. On the other hand, dissolved oxygen in the sludge T is almost zero, and the rate of oxygen replenishment toward both electrodes 2 and 3 is also considered to be slower than in water 6. The effective oxygen concentration on the surface becomes substantially zero. For this reason, the voltage that drops across the load resistor 5 is 0.3 V or more when both electrodes 2 and 3 are in water 6, and is 0.1 V or less when both electrodes 2 and 3 are in sludge 7, and is clearly A significant difference arises. Therefore, the sludge 7 is connected to both electrodes 2,
3 is buried, it is detected as a voltage drop, and this voltage change is amplified by the conversion circuit 8 and the level is indicated to the measuring device 10, and the contact of the relay 9 is activated to send the sequence circuit 11.
A sludge signal is then supplied to the sludge valve 12, and the sludge 7 is discharged.

In addition, 13 is a sludge pump. During this sludge removal, a considerable amount of water flow is generated, so that the sludge 7 adhering to the surfaces of both electrodes 2 and 3 is removed by the water flow. However, when used for a long period of time, the surfaces of both electrodes 2 and 3 become contaminated with sludge 7, so even though both electrodes 2 and 3 are present in water 6, the generated voltage decreases, making it difficult to accurately The disadvantage was that accurate interface detection could not be obtained. In view of the above-mentioned points, the present invention aims to provide an electrode-type sludge interface meter that is easy to handle and maintain, which can prevent the drop in generated voltage due to contamination of the electrode surface, which is a drawback of the conventional technology, and maintain interface detection accuracy. purpose. According to the present invention, in the electrode-type sludge interface meter of the type mentioned at the beginning, when removing sludge adhering to the surface of a pair of detection electrodes, the external circuit is switched. This is achieved by applying a DC voltage to the pair of detection electrodes such that the detection electrode made of a noble metal has a negative potential and the detection electrode made of a base metal has a positive potential. According to the present invention, a DC voltage is applied to a pair of detection electrodes such that the detection electrode made of a noble metal has a negative potential and the detection electrode made of a base metal has a positive potential. Hydrogen gas and oxygen gas are generated at the electrodes, and the sludge adhering to the surfaces of both electrodes is effectively removed by this gas generation.

A changeover switch is provided and the external circuit is changed over by operating the changeover switch.

The changeover switch may be operated manually or periodically by a control device. Next, examples of the present invention are based on the drawings,
Explain in detail.

FIG. 2 shows a schematic configuration diagram of an embodiment of the present invention.

In the figure, parts having the same functions as in FIG. 1 are designated by the same reference numerals. Normally, the electrode system 1 consisting of both electrodes 2 and 3 operates as a galvanic cell type battery system to perform measurements. On the other hand, when attempting to remove sludge adhering to the surfaces of both electrodes 2 and 3, when the changeover switch 16 is switched in response to a signal from the control device 15, the constant voltage power supply unit 1
4 supplies a direct current with a polarity such that the anode electrode 3 made of tagtar cast iron has a positive potential and the cathode electrode 2 made of stainless steel has a negative potential. With this applied current,
Both electrodes 2 and 3 operate as an electrolytic system, and on the surface of the cathode electrode 2, a reaction occurs to reduce dissolved oxygen and generate hydrogen gas. On the surface of the anode electrode 3, an iron dissolution reaction and an oxygen generation reaction occur. At this time, due to gas generation at both electrodes 2 and 3, the sludge adhering to the surfaces of both electrodes 2 and 3 is effectively removed. According to the inventor's experiment, for example, after both electrodes 2 and 3 are immersed in sludge 7 with a concentration of 4% suspended matter, both electrodes 2 and 3 are gently pulled up into water 6. When a DC current of the above polarity having a current density of 500 μNi is applied by the constant voltage power supply section 14, the electrode 2
The sludge adhering to , 3 became scaly and peeled off in about 15 minutes. Also, 1000ttA/c! Similarly, at the current density of N2, the sludge adhering to electrodes 2 and 3 was completely removed in about 5 minutes. On the other hand, when the above-mentioned electric current was not applied and natural peeling was performed, it took about one day for the sludge 7 to be completely removed. Therefore, if the sedimentation tank 4 is drained every 4 hours, the electrode system 1 will operate for 5 hours to remove the sludge 7 attached to the surfaces of the electrodes 2 and 3 as an electrolytic system. About 15 minutes is enough, so
During the remaining time, the interface detection operation between the water 6 and the sludge 7 can be continued using the electrode system 1 as a battery system.

In this way, the selection of the battery system or electrolytic system operating time is determined by the switching signal time by the control device 15. It should be noted that the tagtar cast iron anode electrode 3 can be used for a long time because iron oxide (rust) generated on the surface is easily peeled off and sludge is easily removed together with the iron oxide compared to a normal iron anode electrode.

As explained above, according to the present invention, a polarity DC voltage that gives a positive potential to the power sword electrode and a negative potential to the anode electrode is applied to both electrodes by manual operation or a switching signal from the control device. , both electrodes are switched from a battery system to an electrolytic system, and the sludge adhering to the surface is easily peeled off by the physical action of the gas generated on the surfaces of both electrodes, preventing a drop in the generated voltage due to contamination on the surfaces of both electrodes, and reducing the interface Since detection accuracy can be maintained over a long period of time, it is extremely effective as an electrode-type sludge interface meter that is easy to handle and maintain.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the principle structure of an electrode type sludge interface meter, and FIG. 2 is a schematic diagram showing an embodiment of the present invention. 1: Electrode system, 2: Cathode electrode, 3: Anode electrode, 4
: Sedimentation tank, 5: Load resistance, 6: Underwater, 7: Sludge, 8: Conversion circuit, 9: Relay, 10: Measuring instrument, 11: Sequence circuit, 12: Sludge valve, 13: Sludge pump, 14 : Constant voltage power supply section, 15: Control device, 16: Changeover switch.

Claims (1)

[Claims] 1. A pair of detection electrodes is formed from an electrochemically relatively noble metal and a base metal, and the pair of detection electrodes are placed in a liquid with a predetermined distance from each other. to form a galvanic battery, electrically connect between the pair of detection electrodes of this battery by an external circuit to make this battery system a closed circuit battery system, and detect the voltage or current of this closed circuit battery system. In the sludge interface meter that detects a change in the interface between the liquid and the sludge in the liquid from the detected voltage or current,
When removing sludge adhering to the surface of the pair of detection electrodes,
The external circuit is switched to apply a DC voltage to the pair of detection electrodes such that the detection electrode made of a noble metal has a negative potential and the detection electrode made of a base metal has a positive potential. Electrode type sludge interface meter. 2. In the interface meter according to claim 1, a changeover switch is provided in the external circuit, and when removing sludge adhering to the surfaces of the pair of detection electrodes, the changeover switch is operated to set a constant voltage. An electrode type sludge interface meter characterized in that a DC output voltage of a source is applied to a pair of detection electrodes. 3. In the interface meter according to claim 2, a control device is provided, and when removing sludge adhering to the surfaces of the pair of detection electrodes, the changeover switch is periodically activated by an output signal of the control device. 1. An electrode-type sludge interface meter which is operated to periodically apply a DC output voltage of a constant voltage source to a pair of detection electrodes.