JPS5880039A - Apparatus for controlling water quality - 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 The present invention relates to a water quality control device that detects when the quality of water in a tank has deteriorated and supplies water.

For example, a steam generator is a device in which an electric heater is installed in a tank in which water is poured, and a water supply device is installed to supply water into the tank.The electric heater heats the water and generates steam.

However, this steam generator has the problem that when the water evaporates, the components contained in the water precipitate as scale, degrading the quality of the water.As a result, scale adheres to the surface of the electric heater, causing heat dissipation from the heater. In addition, when a pool tap is used in the water supply mechanism, if scale adheres to the float, it will not work and water supply will be impossible.

Conventionally, as a countermeasure against the deterioration of water quality due to the formation of scale, a method has been used to periodically replace the water in the tank using a timer, but this method is not only uneconomical, but also causes the water to be discharged along with the water. The disadvantage is that the scale solidified in the pipes may cause clogging.

In response to this, the inventor of the present invention has conducted various studies and found that
Focusing on the fact that the specific resistance of water decreases when the water quality deteriorates, and by detecting this decrease in the specific resistance of the water, it can be determined that the water has reached a scale-producing condition. I found a way. In other words, a resistivity detection circuit is connected between a pair of electrodes installed in the tank so that a direct current flows through the water in the tank. When the electrical conductivity decreases and the electrical conductivity increases, the detection circuit captures the corresponding change in the resistance of the electrode and detects the change in the specific resistance of water, and the water supply mechanism supplies water to the tank to renew the water in the tank. This creates a clean condition where no scale is generated.

This method is excellent because it allows you to easily know the state of water scale formation in the tank using simple electrical means. In order to further improve the reliability of water resistivity detection using this method, the present inventors have conducted repeated research to solve problems that are obstacles to increasing this reliability.

Problems in increasing the reliability of water resistivity detection will be explained below.

As mentioned above, as discovered by the inventors of the present invention,
What is important in the method of detecting the decrease in the resistivity of water in a tank to determine the state of water scale generation is to accurately and easily detect the change in the resistivity of water when the water reaches a scale generation state. That's true. For this purpose, it is necessary to eliminate the factors that hinder this and to enable the detection circuit to accurately and easily detect changes in the specific resistance of water.

The equivalent circuit of the detection circuit, that is, the electrode circuit connected to the detection electrode in this detection method is shown in FIG.

That is, a detection electrode 8 and a power supply electrode 9 provided on the tank 1 are connected to a DC power supply E via an internal resistor Ti.

In this circuit, the inventor conducted an experiment to measure the change in the resistance ri of the electrode 8 with respect to the electrical conductivity (1/specific resistance) p of water using the voltage 6 between the electrodes 8 and 9 as a parameter. The results are shown in the diagram in Figure 5.
The electrode voltage is divided into 01 to esK, and the voltage is e! 11<8
2 < es. The results of this experiment revealed the following. That is, the electrode resistance rz of the electrode 8 is proportional to the specific resistance of water and inversely proportional to the electrical conductivity of water. Electrode resistance rX is inversely proportional to electrode voltage e4. Also, the electrode resistance r
When the specific resistance of water becomes smaller than a certain value (when the electrical conductivity becomes larger), the resistance change becomes much smaller and hardly changes due to the internal resistance Ti in the electrode circuit.

This will be explained based on the equivalent circuit shown in FIG.

The electrode voltage e< is expressed by the following formula.

Note that E is the power supply voltage of the electrode circuit. ζNow, from the diagram in Fig. 5, it can be seen that when the electrode voltage e( decreases, the electrode resistance rx increases, so the electrode resistance rz is rz −/ (1/
e7) ...(2), and substituting equation (1) into equation (2) yields 1 rx=/(τ+1). Therefore, when the specific resistance of water decreases (the electrical conductivity increases), the electrode resistance rz decreases accordingly and approaches zero, which satisfies the equation (2) above. Therefore, it can be seen that the electrode resistance rl converges to a certain value in a region where the specific resistance of water is small (if there is an internal resistance r in the electrode circuit). That is, in a region where the specific resistance of water is small (the electrical conductivity is large), the change in electrode resistance with respect to the specific resistance of water approaches zero. If the internal resistance r of the electrode circuit is zero, it will be inversely proportional to the power supply voltage E from equation (2) as rX=f(7).

Therefore, in a region where the specific resistance of water is small, there is almost no change in electrode resistance and it is difficult to detect it.

Furthermore, the inventor conducted an experiment in which changes in the electrode voltage e (and the current in the electrode circuit) were measured using the specific resistance of water as a parameter. The results of this experiment are shown in FIG. 6. The resistance was changed in multiple stages.The specific resistance x1 is the largest value when the water is clean, and below is the specific resistance X2 #X3
Insect resistance X4 is the smallest relatively in the water scale generation state. In this result, when the electrode voltage e( decreases, for example, the operating point i changes to the internal resistance ri
The electrode resistance rx at that time is determined by the intersection of the specific resistance of water and the resistivity I understand. In the region where the current flows through the electrode 8, the internal resistance ri
Therefore, the electrode resistance rx exhibits a very unstable value.

In this way, the internal resistance r is added to the electrode circuit that detects the specific resistance of water.
(If there is, when the water becomes scale-generated and the specific resistance of the water becomes small, there is almost no change in the resistance of the detection electrode 8, making it difficult to detect the change in the specific resistance of the water.

The present invention was made in view of the above-mentioned circumstances, and by detecting changes in the specific resistance of water, it is possible to detect when the water quality has reached a level where scale can occur, and to renew the water to improve the quality of the water. It is an object of the present invention to provide a water quality control device that can maintain water quality, satisfactorily prevent scale generation and the occurrence of accidents associated therewith, and in particular can easily and precisely change the resistivity of water.

In other words, the water quality control device of the present invention reduces the internal resistance in the detection circuit connected to the electrode that detects the specific resistance of water to maintain a constant voltage. By converting changes into large current changes and detecting them, scale generation can be effectively prevented.

Honjitsu 11 will be explained below.

The basic idea of the present invention will be explained.

As shown in Figure 6, from the characteristics shown by the results of an experiment conducted by the inventor in which changes in electrode voltage and current in the electrode circuit were measured using the specific resistance of water as one darameter, the internal resistance of the detection circuit was found to be rl. If the detection circuit is a large constant current type as shown in , for example, it is difficult to distinguish between the specific resistances X4 and X5 of water. Therefore, by reducing the internal resistance of the detection circuit as shown by r2, the specific resistances of water X4 and X5 can be clearly distinguished. That is, from the characteristics shown in FIG. 6, by setting the electrode voltage e4 to a constant voltage, the specific resistance of water
Large current for changes from 1 to X4! change can be obtained. It has been found that this allows a minute change in electrode resistance to be converted into a large, distinguishable change in current. Then, the specific resistance detection circuit is made to have a constant voltage by reducing its internal resistance, that is, by reducing the output impedance.
The resistivity of water is detected as a large change in current.

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

An embodiment in which the water quality control device of the present invention is applied to a steam generator (pan-shaped humidifier) will be described.

FIG. 1 shows the structure of the steam generator, and FIGS. 2 and 3 show the electric circuit.

In FIG. 1, 1 is a tank containing water 2. An electric heater 3 made of, for example, a sheathed heater is provided on the lower side of the inside of the tank 1.
The conductor connected to 4 is connected to @SK@. This electric heater 3 generates heat when energized, and heats the water 2 in the tank 1 to its boiling point to evaporate it. A water supply pipe 6 that is connected to a water supply source such as a water supply and supplies water 2 to the tank 1 is provided above the tank 1, and this water supply pipe σ has a water supply valve, that is, a water supply mechanism, such as a solenoid valve 7. It is a provision. This solenoid valve 7 controls the supply and stop of water to the tank 1 via the water supply pipe 6 by opening and closing operations. That is, the solenoid valve 1 not only supplies water to the tank 1 when the water 2 in the tank 1 is in a state where scale can occur, but also supplies water and adjusts the water level according to the water level in the tank 1 during normal times. It is something.

A pair of electrodes 8.9 for detecting the resistivity of the water 2 are disposed inside the tank 1. One electrode 8 is disposed above the electric heater 3, and the other electrode 9 is disposed above the electric heater 3. are provided at the same height as the electrode 8 with an interval between them, or
It is provided at a distance from the bottom. These electrodes 8, 9
A current is passed through both of them through the water 2 in the tank I, and for example, a resistivity detection circuit IC is connected to one electrode 8 to detect a change in the resistivity of the water 2. In other words, the water 2 is in a state where scale can occur. used for detection. Inside the tank 1 is a pair of electrodes 8. An electrode 10 is provided at the same height as or above the electrode 8, and this electrode 1a detects the normal water level of the tank I by passing an electromagnetic current through the water 2 between it and the other electrode 9, for example. It is used to adjust the These electrodes 8 to 10 are attached to the side wall of the tank 1 by screws so as to be electrically connected to the tank 1, and are connected to the DC power supply circuit 17, 18 through conductive wires (not shown) provided outside the tank 1. It is connected to the. Furthermore, a partition plate 1 is provided inside the tank 1 to separate the electric heater 3 and the electrodes 8 to 10. It is.

Inside tank I, there is a drain pipe (not shown) outside tank 1.
Over 70-pipe 12-AEF & kick foot connected to
When the water 2 in the tank 1 exceeds the set highest water level, it is discharged to the outside from the O-So flow pipe 12.

The electrical circuit associated with solenoid valve r and electrodes 8-10 will be described with reference to FIG. Solenoid valve 2 is contact point Jjm of electromagnetic contactor IJ
is connected to the AC power supply 14 via the electromagnetic contact 1xzz (
coil) is connected in series to the AC power supply 14 together with the contact 15 of the timer relay 15. Electrode 8 is a resistivity detection circuit! This resistivity detection circuit 16 is connected to the timer relay 15 and the control DC power supply circuit IT, 1g. The electrode 1o is connected to a water supply detector 1#, and this water supply detector 19 is connected to a timer relay 15 and a positive DC power supply circuit 17. The electrode 9 is connected to a negative DC power supply circuit 11FIC. In addition,
In the figure, 20 is a transformer.

The resistivity detection circuit 1g is used to set the resistivity of the water 2 inside the tank 1 in advance using the needle side lever, and when it reaches the lower limit value, it detects this and outputs a signal, and the circuit is made to have a constant voltage. Oh,
For example, it has a circuit configuration shown in FIG. That is,
The detection circuit shown in Figures 1 and 3 incorporates a Zener diode zD in order to stabilize the voltage. In FIG. 3, two circuits are connected between the power supplies, each consisting of a Zener diode zD, a variable resistor V for setting the internal resistance of the detection circuit, and resistors R1 and R2. Zener diode z5 is connected to detection electrode 8. operator,
The null amplifier OP consists of a differential amplifier, and this operation.

The Naruan fOP is connected to the connection point BK* between the resistor R1 and the resistor R2 as a reference voltage input terminal, and is connected to the connection point AK between the variable resistor vIE and the Zener diode Z as a measurement signal input terminal. Operation, Naruan fOP
The output end of is connected to timer relay 15. Also,
A feedback resistor RF is connected in parallel to the operating and null amplifier OP.

In the steam generator configured in this manner, the water 2 inside the tank 1 is heated and evaporated by energizing the electric heater 3 to generate heat.

Normal water level adjustment in tank 1 will be described. Luminous pressure is applied between the electrodes 10 and 1) by the DC power supply circuit 17°JIVC, and when the electrodes 1o and 9 are in the water z of the tank 1, a current flows between them via the water 2. tank 1
When the water 2 inside evaporates and the water level becomes lower than the electrode 10,
No current flows between the electrodes 10.9. Then, the water supply detector 19 operates, and the timer relay 15 linked therewith operates to close the contact 16a, thereby connecting the electromagnetic contactor 13 (the coil thereof) to the AC power supply 14 and connecting the contact 16a.
a closes. Therefore, the solenoid valve 1 opens and the water supply pipe 6
Water is then supplied to tank 1. On the other hand, the water level inside the water supply tank 1 rises above the electrode 10, causing the electrode 1
When a current flows between 0.9 and 0.9, the water supply detector 19 operates,
When the timer relay 15 opens the contact 161L after a certain period of time, the power supply from the AC power source 14 of the 13 electromagnetic contactors is cut off, and the contact 134 is opened. Therefore, the electromagnetic valve 7 is closed and the water supply to the tank 1 is stopped.

Furthermore, a case will be described in which the state in which scale is likely to occur in the water is determined by detecting a change in the resistivity of the water 2 inside the tank 1, and a picture book is sent to the tank 1. The electrodes 8 and 9 are located inside the water 2 of the tank 1, and a current flows between them through the water 2. The resistivity detection circuit 16 measures the resistivity of the water 2 based on the current flowing between the electrodes 8 and 9 in accordance with the resistance value of the water 2. Then, while water level adjustment is repeated as described above, the water 2 inside the tank 1 becomes concentrated, so that the specific resistance value of the water 2 decreases. Therefore, under constant voltage, the electrodes 8 and 9
In the meantime, the current flowing through the water 2 increases. When the resistivity value of the water 2 reaches the lower limit of the preset range and a scale can be generated, the resistivity detection circuit 16 operates and outputs a signal, which causes the timer relay 15 to operate and contact 1
5 is closed, solenoid valve 7 is opened and water is supplied to tank 1.

When the amount of water 2 inside this water supply tank 1 increases,
The specific resistance value of water 2 increases. When the resistivity value of the water 2 reaches the preset upper limit, the resistivity detection circuit 16 is activated and the timer relay 15 opens the contact 15a after a certain period of time (for example, 5 to 6 seconds). Valve 7 is closed and water supply to tank 1 is stopped. In this case, when the water 2 inside the tank 1 exceeds the upper limit water level, it is discharged from the overflow pipe 12 to the outside of the tank 1. In this way, when the water 2 inside the tank 1 reaches a state where scale can occur, that is, when scale is about to occur, the resistivity detection circuit 16 detects that the electrode 8
The solenoid valve 7 operates to supply water and make the water 2 scale-free. Therefore, the water inside the tank 1 can be automatically controlled to always be in a scale-free state, and the precipitation of scale in the water 2 can be prevented. As in this specific resistance detection method, it is also possible to control the specific resistance value around a certain specific resistance value without giving a range to the specific resistance value. Note that the electrodes 8 to 10 have a length of 4, for example.
The equivalent circuit of the detection circuit shown in FIG. 3 is shown in FIG. 8. Here, depending on the resistance setting of the variable resistor vl, the change in the diode zD
Distribute the voltage to. When the resistance of the electrode resistance rz is large, the Zener diode zD operates to ensure the Zener voltage E, and the electrode 8 is kept at a constant voltage.

That is, when 6s-E·□>Ez Vt+rx, the electrode voltage e4 is maintained at the Zener voltage E2.

The operation of the detection circuit will be explained below. The variable resistor V is set to a very low resistance value as an internal resistance.

When the water in the tank 1 is clean and the specific resistance of the water is large, the electrode resistance rz of the electromagnetic 8 is correspondingly large. Therefore, when the potential at the connection point A between the variable resistor vl and the Zener diode zD is high, the Zener diode zD becomes conductive. In this case, the voltage of the zener diode-PZD is high, and the voltage e of the electrode 8 is kept at a constant high voltage. Accordingly, the resistance rz of the electrode 8 also decreases.For this reason, the variable resistance vR and the Zener diode-PzD
The potential at connection point A decreases.

In addition, the voltage at the connection point A between the variable resistance V blade and the Zener diode zD is compared and measured using the voltage at the connection point B between the resistor r1 and the resistor r2 as a reference voltage. The specific resistance of the water that causes scale generation decreases, and when the voltage at the connection point decreases,
In a reliable state where Naruan 7'OP operates and a water supply command is issued, the part connected to Zener diode zD Nyoshimi pole 8 is held at a constant voltage, and the water becomes scaled and the specific resistance decreases. Sometimes, because the internal resistance of the detection circuit is small, a change in the quality of the water is detected as a change in the resistance of the electrode 8. That is, a change in the resistance of the electrode 8 when the specific resistance of water decreases can be detected as a large change in current.

For example, in Figure 6, when the specific resistance of water is X4, the internal resistance r
Since the resistance change is detected using the point where it intersects with 2 as the operating point, the resistance change can be converted into a large current change. Therefore,
It is possible to easily and precisely detect a change in the specific resistance of water when water scale is generated, and to reliably prevent water scale generation.

The specific resistance detection circuit 16 is not limited to the above-described circuit configuration, but it may be of any type as long as the internal resistance is small, the voltage is constant, and the resistance change of the electrode 8 is made to be a large current change.

For example, FIG. 4 shows the configuration of a detection circuit in which transistors are connected in emitter and seven-orer junctions. Note that the same parts as in FIG. 3 are designated by the same reference numerals, and their explanation will be omitted. In FIG. 4, the base of an NPN transistor Tr is connected to a resistor 5 (connection point with a resistor 7) connected between the power supplies, the collector of the transistor Tr is connected to a variable resistor viL, and the emitter and is connected to the resistor R5 connected to the negative power supply,
Furthermore, the emitter connection point of the transistor Tr is connected to the electrode 8. Next, a case will be described in which specific resistance of water is detected in this detection circuit. The potential ED at point D connected to the electrode 8 is the potential E0 at point 0 since this circuit is a pace grounding circuit, and the voltage ED excluding the pace emitter voltage mab of the transistor Tr is EDwt7. , -vb.

becomes. However, since voltage ma b0 remains approximately constant with respect to changes in collector current Ic, ED remains a constant value. Therefore, the electrode resistance rz of the electrode 8 changes on the curve of voltage e1t e2ze3 shown in FIG. Therefore, if the current flowing through the electrode 8 is lx, then the emitter current I of the transistor Tr is ED ■8 votes□ z .

The collector current of the transistor! . , if the current amplification factor is β, then Ie-(I.-Ib)1. (1-7) β〉00 hours, 1
1. '4:10, therefore, the variable resistance V! Therefore, the potential E at the connection point F between the collector of the transistor Tr and the variable resistor vl is: r) (The specific resistance decreases, d electrode resistance r8 becomes small, and the voltage Eν decreases.On the other hand, the potential Eo at the connection point G between the resistors R1 and R2 is taken as a reference voltage, and the connection point F When the voltage at the connection point y decreases due to a decrease in the specific resistance of the water, the voltage at the connection point y is activated and the timer relay 15 is activated. Outputs the signal.

The water supply valve in the steam generator of the present invention basically supplies water to the tank when the resistivity detection electrode and the resistivity detector detect that the water in the tank is in a state where scale generation is possible. This is the role of the director. In the embodiment described above, a water supply level detection electrode and a water supply level detector are provided to electrically detect the water supply level in the tank, and the water supply valve has the function of supplying water for normal water level adjustment.

However, K is not limited to this, and for example, a water level regulator such as a turn tap may be provided separately from the water supply valve to mechanically control the normal water level. The water supply valve is not limited to a solenoid valve, and may be any valve that operates in response to a signal from a resistivity detector. Further, the mechanism for supplying water to the tank is not limited to the water supply valve, and for example, a water supply pump may be used and driven to supply water. Furthermore, it is also possible to use the tank as a negative side electrode without providing a dedicated electrode as a negative side electrode.

Furthermore, the present invention is not limited to application to steam generators, but can also be used for water quality control in tanks in tanks, water quality control in cooling towers, water quality control of other industrial water, etc. It can be widely applied as a device that detects a state in which scale can occur by using resistance change and renews the water to keep the water in a good condition and prevent scale from occurring.

As explained above, the water quality control device of the present invention uses a simple electrical means that utilizes changes in the specific resistance of water to prevent scale formation in the water and maintain good water quality at all times, and in addition, It also prevents functional deterioration due to scale build-up on instruments installed inside the tank. Furthermore, there are no problems such as uneconomical costs or clogging of pipes, which would be caused by replacing the water in the tank at regular intervals to remove scale.

By reducing the internal resistance of the resistivity detection circuit that detects the specific resistance of water and making it a constant voltage, the amount of change in the signal current from the detection electrode is increased. When the resistivity of the water decreases, the resistivity of the water can be easily and precisely detected, and the water quality can be properly managed by ensuring reliable and stable renewal of the water.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional front view showing a steam generator which is an embodiment of the present invention, Fig. 2 is an electric circuit diagram of the same embodiment, and Figs. 3 and 4 are examples of different resistivity detection circuits. Fig. 5 is a diagram showing the relationship between the electrode resistance and the electrical conductivity of water with the electrode voltage in Δ rammeters, and Fig. 6 is a diagram showing the relationship between the electrode voltage and the electrical conductivity of water with the specific resistance of water in /9 rammeters. 7 and 8 are circuit diagrams showing the equivalent circuit of the husband undetected circuit. 1-tank, 2-water, 3... electric heater, 4...
Water supply pipe, 7 - Solenoid valve (water supply mechanism), 8, 9, 10...
- Electrode, 16... Specific resistance detection circuit, 19... Water supply level detector. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 15 Figure 3 Figure 15 J16rI! J t contact voltage (ej) Fig. 7

Claims (1)

[Claims] A tank containing water, a pair of electrodes that conduct a current through the water contained in the tank, and a pair of electrodes connected to one of these electrodes to measure the specific resistance of the water inside the tank and to calculate the ratio of this water. A resistivity detection circuit that outputs a signal when the resistance reaches a set value and detects a change in the resistivity of water at the electrode as a large current change by reducing the internal resistance, and a signal from this resistivity detection circuit. A water quality control device comprising: a water supply mechanism that operates to supply water to the tank.