JPH0457750B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water treatment device that electrochemically treats water.

This type of water treatment device removes or prevents scale from adhering to water pipes or prevents rust by passing an electric current between electrodes immersed in water to be treated. The effect of preventing scale adhesion or rust is proportional to the amount of current applied according to Faraday's law. Therefore, when treating water of a certain quality at a constant flow rate, by passing a constant current between the electrodes. Good processing can be performed.

FIG. 1 is a diagram showing the circuit configuration of a conventional water treatment device, and in this example, a constant current circuit is incorporated in order to flow a constant current between electrodes. 1 is a DC power supply, and 2 and 2' are a pair of electrodes immersed in the water to be treated. Reference numeral 3 denotes a current control means consisting of a transistor or the like, and is used to control the current flowing from the DC power supply 1 to the electrodes 2 and 2'. 4 is _an error amplifier, _{E 1} is a reference power supply, and R ₁ is a resistor. The control means 3 is activated, so that a constant current flows between the electrodes 2, 2'.

However, when a water treatment device having such a configuration is applied to a circulating cooling water system, the following problems occur.
In other words, in a circulating cooling water system, the amount of water that evaporates into the atmosphere changes depending on the amount of cooling water loaded, so the concentration of the cooling water changes, and therefore the concentration of scale components in the cooling water changes depending on the amount of cooling water loaded. It fluctuates. Therefore, the amount of excess scale components to be removed will vary even if the amount of circulating water is constant. Furthermore, city water, industrial water, or the like is generally used as supplementary water for cooling water, but the quality of these waters is usually not constant at all times but changes seasonally. In this way, the amount of scale components to be removed varies depending on changes in the cooling water load and the quality of the make-up water, but the method of flowing a constant current between electrodes 2 and 2' has a poor ability to remove scale components. Since it is always constant, fluctuations in the amount of scale components will cause excess or deficiency in removal ability.
If the removal capacity is insufficient, the quality of the circulating water will deteriorate and scale failure will occur, rendering the installation of the water treatment device useless. On the other hand, if the removal capacity becomes excessive, the current continues to flow and the quality of the water improves, but the conductivity of the water decreases, causing an increase in the voltage between the electrodes 2 and 2'. If the voltage increases abnormally, reactions such as electrolysis of water occur, which may generate gas or cause corrosion, and there is also a risk that the DC power supply 1 will break down withstand voltage. Also, the magnitude of the current flowing between electrodes 2 and 2' is
When installing a water treatment device in a circulating cooling water system where the cooling water is of poor quality because it is designed to treat cooling water with standard water quality (water that contains scale components in an amount that does not cause any risk of scale failure). It was necessary to replace the cooling water with standard water at the time of installation. If water treatment were to be carried out without replacing the cooling water, it would take a long time for the water quality to reach standard water quality, and there was a risk of scale failure occurring during that time.

The present invention was developed under these circumstances, and it is possible to always perform good water treatment, and it does not cause electrolysis of water, causing corrosion or gas generation. The purpose of this project is to provide a water treatment system that does not require

The present invention is characterized by detecting the current flowing between the electrodes in a water treatment apparatus that performs water treatment by passing a DC current between a pair of electrodes immersed in water to be treated using a DC power source. a current detection circuit; a voltage detection circuit that detects the voltage between the electrodes; an output terminal of the current detection circuit and an output terminal of the voltage detection circuit are connected to one input terminal; , an error amplifier connected to a reference power source that generates a preset reference voltage, and a current that is provided between the DC power source and the electrode and controls the current flowing between the electrodes according to the output voltage of the error amplifier. A control means is provided, and when the voltage between the electrodes is below a predetermined voltage, the output voltage of the current detection path is higher than the output voltage of the voltage detection circuit, and when the voltage between the electrodes exceeds the predetermined voltage, the output voltage of the voltage detection circuit is The point is that the output voltage is greater than the output voltage of the current detection circuit.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a circuit diagram showing an embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate the same or equivalent parts. Reference numeral 5 denotes a current detection circuit for detecting the current flowing between the electrodes ₂ and ₂ '. It consists of a first buffer amplifier 51 whose ends are connected. 6 is electrode 2, 2'
This is a voltage detection circuit for detecting the voltage between
In this example, it consists of a resistor R ₃ connected in parallel to the electrodes 2 and 2', and a second buffer amplifier 61 whose input ends are connected to both ends of this resistor R ₃ , respectively. Reference numeral 7 denotes an error amplifier, and one input terminal of the error amplifier 7 is connected to the output terminals of each of the first buffer amplifier 51 and the second buffer amplifier 61. Further, the other input terminal of the error amplifier 7 is connected to a reference power source _E2 that generates a preset reference voltage,
The output end of the error amplifier 7 is connected to the current control means 3. Regarding the ratings of the circuit components of the current detection circuit 5 and voltage detection circuit 6, when the voltage between the electrodes 2 and 2' is below a predetermined voltage,
The output voltage of the first buffer amplifier 51 is higher than the output voltage of the second buffer amplifier 61, and the electrode 2,
2' exceeds a predetermined voltage, the output voltage of the second buffer amplifier 61 changes to the first buffer amplifier 5.
The output voltage is selected to be greater than the output voltage of 1. Here, the magnitude of the above-mentioned predetermined voltage is, for example, the magnitude of the voltage between the electrodes 2, 2' when the water to be treated interposed between the electrodes 2, 2' is in a standard water quality state.

Next, the operation of the embodiment will be explained. First, if the water to be treated between the electrodes 2 and 2' contains a large amount of scale components and is of poor quality that is inferior to the standard water quality state, the conductivity of the water to be treated is high and the electrodes 2, 2'2' voltage is lower than the predetermined voltage.
Therefore, the output voltage of the first buffer amplifier 51 is higher than the output voltage of the second buffer amplifier 61, and the output voltage of the first buffer amplifier 51 is input to the error amplifier 7, and the output voltage of the first buffer amplifier 51 is inputted to the error amplifier 7. , a voltage corresponding to the difference between the input voltage and the reference voltage is output.
The current control means 3 is activated by the output voltage of the error amplifier 7, and the current flowing between the electrodes 2 and 2' is controlled so that the difference between the input voltage of the error amplifier 7 and the reference voltage becomes zero. That is, the current flowing between the electrodes 2 and 2' is controlled to be a constant current. In this way, as the current flows through the water to be treated, the removal of scale components in the water to be treated progresses.
As the electrical conductivity of the water to be treated decreases, the voltage between the electrodes 2 and 2' increases. When the water to be treated reaches the standard water quality state, the voltage between the electrodes 2 and 2' exceeds a predetermined voltage, so the output voltage of the second buffer amplifier 61 is higher than the output voltage of the first buffer amplifier 51. The output voltage of the second buffer amplifier 61 is input to the error amplifier 7. As a result, the current control means 3 is activated and the current between the electrodes 2 and 2' is controlled so that the difference between the input voltage of the error amplifier 7 and the reference voltage becomes zero. In this case, the current is controlled so that the voltage between the electrodes 2 and 2' becomes a constant voltage. The voltage between the electrodes 2 and 2' when shifting from constant current control to constant voltage control needs to be set below the water decomposition voltage, thereby avoiding water electrolysis. Furthermore, when switching to constant voltage control, the current flowing between electrodes 2 and 2' decreases, but at this time the water to be treated is of good quality, so even a small current can effectively remove scale. work. Note that the water decomposition voltage referred to herein is a voltage that includes activation overvoltages due to electrodes and other overvoltages. FIG. 3A is a characteristic diagram showing the relationship between the voltage between electrodes 2 and 2' and the current flowing between electrodes 2 and 2' for the water treatment device of the embodiment, and FIG. 3B is a characteristic diagram of the conventional water treatment device shown in FIG. It is a characteristic diagram which shows the same relationship about a water treatment device. In the figure, V ₀ is the water decomposition voltage. As can be seen from Figure 3A and B, as the scale components are removed, the conductivity of the water decreases, and the voltage between electrodes 2 and 2' increases, the water quality improves with the conventional method. However, in the example, the current decreases before reaching the water decomposition voltage and is maintained at a predetermined voltage. Water electrolysis does not occur.

According to the above embodiment, constant current control is performed while the water to be treated is of poor quality with many scale components, and constant voltage control is performed when the water to be treated is of standard water quality with few scale components. As a result, a large current necessary to improve water quality flows for treated water with many scale components, whereas a small current flows for treated water with few scale components, so the scale components due to energization are reduced. The removal ability automatically follows the amount of scale components in the water to be treated. As a result, even when performing water treatment in a circulating cooling water system, there is no excess or deficiency in the scale component removal ability due to fluctuations in the amount of scale components due to changes in the cooling water load, etc., so good water treatment can always be performed. There is no risk of scale failure, and since water electrolysis does not occur, there is no corrosion or gas generation. Furthermore, after the water to be treated is of good quality, the current is reduced, so power consumption is small, which reduces running costs and saves energy. In addition, in the past, when installing a water treatment device to cooled hydrogen that had become of poor water quality, it was necessary to replace the cooling water with one of standard water quality, but according to the above embodiment, until the cooling water reaches standard water quality, The scale component is rapidly removed by passing a current higher than the flow rate,
After the cooling water reaches the standard water quality state, the current can be reduced by shifting to constant voltage control, and the water quality can be quickly changed from poor water quality to good water quality without replacing the cooling water.

Next, an experimental example in which water treatment was performed using the water treatment apparatus according to the present invention will be explained. Figure 4 shows that the flow rate of cooling water was 90 tons per hour, and a water treatment device was installed in a circulating cooling water system that used city water as make-up water. This is a graph showing the results when performing the following. 1 to 3 in the diagram
are the scale component concentration (Ca(HCO ₃ ) ₂ concentration),
and power consumption and hydrogen ion concentration (PH). The concentration of scale components is approximately at the beginning of water treatment.
It was 130mg/, but after that it rapidly decreased to about 40mg/ at the end of July, and has remained at approximately this value since then. On the other hand, the middle term for power consumption in July is
Although it exceeded 0.8Kwh, it decreased rapidly after that, reached 0.1Kwh at the end of July, and has remained at approximately this value since then. From this result, it is understood that the cooling water, which had poor water quality before the start of water treatment, quickly changed to good water quality by operating the water treatment equipment, and also that the cooling water had good water quality. It can be seen that after the current is reached, the current decreases and power consumption can be reduced. The hydrogen ion concentration was maintained between approximately 7 and 8 from the start of the water treatment and thereafter, and was approximately constant, indicating that water was not electrolyzed.

As described above, according to the present invention, constant current control is performed while the water to be treated is of poor quality with many scale components, and constant voltage control is performed when the water to be treated is of good quality with few scale components. As a result, a large current necessary to improve the water quality flows for treated water with poor quality, and a small current necessary for effective removal of scale components flows for high quality treated water. Therefore, there is no excess or deficiency in the ability to remove scale components due to fluctuations in the amount of scale components. Therefore, it is possible to always perform good water treatment and there is no risk of scale failure.
Moreover, since water electrolysis does not occur, corrosion and gas generation do not occur. Therefore, it can be suitably used, for example, for water treatment in a circulating cooling water system.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing a conventional water treatment device, Figure 2
The figure is a circuit diagram showing a water treatment device according to an embodiment of the present invention, and FIGS. 3A and 3B are current-voltage characteristic diagrams of the water treatment device of the embodiment and current-voltage characteristics of a conventional water treatment device, respectively. 4 are graphs showing the results of Examples of the present invention. 1... DC power supply, 2, 2'... Electrode, 3... Current control means, 5... Current detection circuit, 6... Voltage detection circuit, 51, 61... Buffer amplifier, 7... Error amplifier, E ₂ ...Reference power supply, _R2 , _R3 ...Resistance.

[Claims]

1 Electrodeposition is carried out by supporting a pair of electrolytic type gauges with their tips abutting each other in an electrolytic bath, and when the desired electrodeposited layer is obtained, it is taken out and cut at the butt part, An electroforming method for tubular objects such as bushings, which is characterized by finishing each piece to the product dimensions.