JPS62167457A - Method and apparatus for measuring concentration of salt component of water - Google Patents

Abstract

PURPOSE:To make it possible to accurately and rapidly adjust and hold the concn. of the salt component of a laver forming stock material, by detecting the concn. of the salt component of the water mixture in a water mixture conditioning tank by a concn. sensor using a constant voltage oscillation modulation signal. CONSTITUTION:A power source circuit 8 receives the current of a commercial frequency to supply the same not only to the AC power source of each circuit but also to a DC constant voltage power source through a rectifier circuit 8a and a constant voltage circuit 8b. An oscillation/modulation circuit 9 receives DC constant voltage and obtains predetermined high frequency output by an oscillation circuit 9a such as a monostable multivibrator. In this case, frequency is fixed or made variable. A standard level is adjusted by a standard level adjusting circuit 9b having a resistor and a condenser etc. so as to obtain high frequency output equilibrated positively and negatively. This frequency output is applied to the electrodes 24, 25 of a concn. sensor 5 and a concn. sensor 5 is operated to input said output to a concn. control circuit 10 through a temp. correcting thermistor 26 operated by a water temp., is necessary.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a method for detecting the salinity concentration of water used for adjusting the seaweed concentration of raw material for seaweed cutting supplied to a seaweed cutting machine. The present invention relates to a measuring method and an apparatus for carrying out the method.

[Prior art and its problems]

Traditionally, when making nori sheets, adding a small amount of salt to the raw materials for nori sheets improves yield, color, and gloss, but if there is too much salt, the seaweed may absorb moisture during storage, or
It is known that salt may precipitate during subsequent processing and impair quality.

In addition, a large amount of seaweed raw material must be continuously supplied to the seaweed machine at all times, and in order to maintain the salinity within the specified range, the salinity of the water that is mixed with the seaweed raw material and adjusted to the concentration must be It is required to constantly measure the concentration while supplying it accurately and in large quantities.

Conventionally, the common method for measuring the salinity concentration of water was to measure the change in electrical conductivity between electrodes using a direct current, but when measuring salinity, air bubbles due to electrolysis adhere as time passes. or errors may occur due to changes in water temperature.
It was difficult to make accurate measurements. In order to improve this problem, there is a device that uses a very small direct current to perform precise measurements, but it is extremely expensive.

[Purpose of the invention]

In view of the above-mentioned points, the present invention enables accurate and continuous measurement of salt concentration, maintains the salinity of seaweed raw material within a specified range, and does not interfere with large-scale supply. The purpose is to make it possible to properly and quickly adjust and maintain the salt concentration of raw materials, and to obtain an economical device for this purpose.

[Structure of the invention]

The present invention generates a predetermined high frequency signal from an oscillation modulation circuit in response to a DC constant voltage power supply, adjusts the reference level of the output high frequency signal to produce a high frequency output signal with positive and negative balance,
applying this output signal to an electrode of a concentration sensor in water;
Alternatively, there is a method for measuring the salinity concentration of water, which is characterized in that the output signal of the concentration sensor is outputted through a temperature correction circuit that operates depending on the water temperature, and a power supply circuit that provides a DC constant voltage power supply; An oscillation modulation circuit that receives a constant voltage and generates a predetermined high-frequency signal using an oscillation circuit, a reference level adjustment circuit that adjusts the reference level of the output signal of the oscillation modulation circuit, and a high-frequency signal that is immersed in water to be measured and passes through the adjustment circuit. This water salinity measuring device is characterized in that it is equipped with a concentration sensor having a pair of electrodes that receive water, or in which a temperature correction element that senses water temperature is incorporated into the concentration sensor.

〔Example〕

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

Figure 7 shows a flow sheet of the method and apparatus for adjusting the concentration of seaweed as raw material for seaweed cutting, in which raw seaweed is minced by cutting it into small pieces using a mincing machine, and the seaweed is thoroughly washed with water. After removing salt and impurities, the minced seaweed is processed into a blender to create a mixture of seaweed and water.
That is, a seaweed mixture is prepared, and this seaweed mixture is temporarily stored in a seaweed mixture stirring tank while being stirred. The concentration can also be adjusted in the stirring tank as needed. In this case, the water is
Mixed water with a certain concentration added with a slight amount of salt.

A pump (P3) is installed from the mixed water adjustment tank that stores and adjusts the mixed water.
) to the blender, and water required for concentration adjustment is supplied by a pump (P4). Fresh water is pumped from the freshwater tank and seawater is pumped from the seawater tank to the mixed water adjustment tank (P.
, ), (P, ).

The mixed water adjustment tank is equipped with a concentration sensor that detects the salinity concentration and a water level sensor that detects the water level in the tank.The mixed water control device has a concentration control circuit that operates in response to the concentration sensor output, and a concentration control circuit that operates in response to the output of the water level sensor. A water level control circuit that operates based on the concentration control circuit, a drive circuit that operates in response to the output of the concentration control circuit, and a drive circuit of the mixed water control device that operates in response to the output of the concentration sensor and the water level sensor. (P□) and (P,) are operated to control the supply amount of fresh water and seawater, and therefore the supply amount and salinity of mixed water. The seaweed mixture from the blender is fed to the seaweed mixture stirring tank,
The seaweed mixture stirred and adjusted in this stirring tank is supplied to a seaweed machine.

Figure 8 shows an embodiment of the salinity adjustment device for mixed water mixed with seaweed raw material, in which the mixed water adjustment tank (1) has fresh water from the fresh water tank (2), fresh water from the seawater tank (3) They are installed so that seawater is sent and stored by pumps (P) and (P2), respectively.

The mixed water adjustment tank (1) includes a stirrer (4) for stirring the mixed water stored in the tank, a concentration sensor (5) for detecting the salt concentration of the mixed water, and a preset water level in the tank. A water level sensor (6) is installed which operates and issues a signal when the high water level (H level) and low water level (L level) are reached. The mixed water control bag rR (7) includes a power supply circuit (8), an oscillation modulation circuit (9), and a concentration control circuit (10).
), water level control circuit (14), first drive circuit (15),
Second drive circuit (16), display circuit (17), indicator light (
18), an alarm circuit (19), and an alarm buzzer (20). The concentration control circuit (10) consists of a rectifier (11), an amplifier circuit (12), and a signal discriminator (13). The outputs of the first and second drive circuits (15) and (16) drive a pump (pzL (Pi)) which is a means of supplying fresh water and sea water, and fresh water is supplied from the fresh water tank (2) and the sea water tank (3), respectively. , seawater is supplied to the mixed water adjustment tank (1).Valves (V□) and (V2) are placed in the supply channels of freshwater and seawater as means to adjust the supply amount of each, and the supply amount per hour is adjusted. Seaweed and water are supplied to the mixing machine (21), but the water is pumped from the mixing water adjustment tank to the pump (P
,) powered by.

The seaweed mixture is supplied from the mixer (21) to the seaweed mixture stirring tank (22), and if it is necessary to adjust the seaweed concentration here, water for adjustment is supplied from the mixing water adjustment tank (1) to the pump (P4).
) powered by The seaweed mixture stirred and adjusted in the seaweed mixture stirring tank (22) is supplied to the seaweed machine as a raw material for seaweed cutting.

FIG. 1 shows an embodiment of the concentration sensor according to the present invention, in which electrodes (24) are arranged at a predetermined interval within an insulating cylinder (23).
(25), its tip protrudes into the cylindrical body (23), and its base is embedded in the cylindrical body, with a signal line (24a),
(25a) is derived. One of the electrodes, e.g. (25)
is a temperature compensation circuit (such as a thermistor) for the sensor output.
26).

FIG. 2 shows an embodiment of the concentration measuring circuit according to the present invention.

The power supply circuit (8) supplies AC power to each circuit of the control device, and also supplies AC power to each circuit of the control device through a rectifier circuit (8a) and a constant voltage circuit (8b).
Supplies DC constant voltage power.

The power supply circuit (8) receives commercial frequency alternating current, rectifies it, and once converts it to direct current, but a constant voltage circuit is incorporated in this process, so that a constant voltage alternating current can be obtained when high frequency is generated in the subsequent stage. In the range of ±20% voltage fluctuation on the power supply side, there is no effect on the secondary side and concentration measurement is stabilized.

The oscillation modulation circuit (9) receives a DC constant voltage and obtains a predetermined high frequency output using an oscillation circuit (9a) such as an astable multivibrator. The output waveform at this output end point A is the third
Shown in Figure (a). In this case, the frequency may be fixed or variable. Further, the reference level is adjusted by a reference level adjustment circuit (9b) including a resistor, a capacitor, etc., so as to obtain a high frequency output with positive and negative balance. The output waveform at this output end point B is shown in FIG. 3(b). This frequency output is applied to the electrodes (24) and (25) of the concentration sensor to activate the concentration sensor (5). The output of the concentration sensor (5) is input to the concentration control circuit (10).

The reasons for using a balanced high frequency wave as a power source for the concentration sensor are that if a direct current component is included, the mixed water will electrolyze and the generated gas will adhere to the electrodes, causing measurement errors. This is because the temperature-concentration (water resistance value) characteristics are more stable than in measurements, and measurement errors due to temperature changes can be reduced.

FIG. 4 shows an example of temperature-water resistance value characteristics. Salinity concentration 0
．． The characteristics of the water resistance value measured by high frequency measurement and commercial frequency measurement are shown for the case of 0.05 to 3%, and it can be seen that in both cases, the degree of change in the resistance measurement value is smaller and more stable with high frequency measurement. It has been confirmed that good results can be obtained when the frequency of this high-frequency power source is about 1 kHz or higher, and even if it is lower than that, at least measurement is possible, although there are differences in the degree of change. Additionally, if the power supply voltage fluctuates, the current value and therefore the apparent detected salinity concentration value will fluctuate for the same resistance value, making accurate detection impossible and making proper control impossible. A constant voltage circuit for the power supply is required for proper control.

The input signal to the concentration control circuit (10) is a rectifier (11),
The signal is processed by the amplifier circuit (12) and compared with a preset concentration reference value in the signal discriminator (13) to determine whether the concentration is within the reference value range. In this case, for example, 5-level signals (S), (S2)...(S,
), and if it is within the standard value range, it is called [good J (S3), and if it is on the "dark" side of the standard value range, it is called "dark J (S2)", or "dark J (sl)" depending on the degree of the concentration difference. , the "light" side is "thin" (S4), "light" (
S, ).

These five levels of signals are each supplied to a display circuit (17), and one of them is displayed by discrimination. Depending on this signal (Sl) ~ (Ss), the indicator light, ~
The status of the detected concentration of mixed water is displayed by lighting either of L and L. That is, Ll, L,...Ls are each "
Displays ``excessive'', ``dense'', ``good'', ``light'', and ``poorly treated''. In addition, there is also a ``dense'' signal (S) or a ``low treatment'' signal (S).
5) is activated, the alarm circuit (19) is activated and the alarm buzzer (20) is sounded, indicating that the mixed water concentration is
Let them know that they are being treated poorly or poorly.

The "dark" signal (Sl) and the "dark" signal (S2) are the first
The drive circuit (15) is activated, and the "thin" signal (S
4) and the “low treatment” signal (S5) are sent to the second drive circuit (
16) is activated. The first drive circuit (15)
It receives and outputs the "concentration" signal (S2) and the "concentration" signal (Sl), drives the pump (Pl), and supplies fresh water from the fresh water tank (2). Moreover, the second drive circuit (16)
It receives and outputs the "thin" signal (S4) and the "thin" signal (S,), and drives the pump (Pl) to move the seawater tank (3)
Supply more seawater. The supply of fresh water and seawater continues until the above signal is lost. At a “good” signal (S,),
Both drive circuits (15) and (16) stop, and the pump (P
l) and (Pl) both stop.

The water level sensor (6) has a high water level electrode (6a) for detecting a high water level (H level) and a low water level electrode (6b) for detecting a low water level (L level). When the water level falls below the L level, both drive circuits (15) and (16) are operated to simultaneously drive the pumps (p 1 ) and (p z ) to simultaneously supply fresh water and seawater. During this time, the signal from the concentration sensor is ignored, and the concentration is roughly adjusted by adjusting the valves (Vi) and (vz) so that the supply ratio of freshwater and seawater matches the standard concentration.

The valve (V□L (Va)) is generally adjusted manually, but it can also be controlled by an electric signal or the like as a power method.

When the water level reaches the H level, both freshwater and seawater are stopped being supplied, and from this point on, the concentration control circuit (10) makes a distinction based on the signal from the concentration sensor (5), and finely adjusts the concentration using the method described above.

During this time, the mixed water is pumped (P3), (P,) to the blender (21) or the seaweed mixture stirring tank (22), respectively.
The water level is gradually lowered. As soon as the water level falls below the L level, both drive circuits (15) and (16) are activated to simultaneously supply fresh water and seawater, and the above steps are repeated. In view of the above operation, the concentration sensor (5) should be installed at a position below the L level.

Figure 8 shows concentration and water level control in the mixing water control device;
An example of a drive circuit is shown.

(101) and (102) are control power supply terminals, (103
) are water level detection signals, low water level detection signal (103a) (normally closed contact), high water level detection signal (103b) (normally closed contact)
Connect the power terminal (
101) and (102). In addition, the self-holding contact (mal) of the auxiliary relay (m) is signaled (103a).
Connect in parallel with The auxiliary relay (m) is the water level control circuit (
104) and its auxiliary normally closed contact (maz)+
(ma□) are connected in series with a freshwater pump (P□) and a seawater pump (Pl), respectively, and are connected to power terminals (101).

(102) Connect between. (105) and (106) are the salt concentration detection signals, (tOS) is the operating signal when the rich side is detected, and (106) is the operating signal when the thin side is detected. ma, ),
(ma,) is connected in parallel with nine. Although these circuits are configured as contact circuits, it is of course possible to configure them as non-contact circuits.

To explain the operation of the above circuit, the low water level signal (10
When 3a) is activated, the auxiliary relay (m) is activated and the pump (
Pi) and (Pl) are driven, and the high water level signal (103b
) operates, the auxiliary relay (m) opens and the pump (P
Stop driving of the engineering L (P,).

On the other hand, when the “concentration” or “concentration” signal is activated, the pump (
P) is driven and if the same signal is lost, it will stop. Also,
When the "concentration" and "overconcentration" signals are activated, the pump (Pl) is driven, and when the signal is lost, the pump (Pl) is stopped.

Next, the operation of the thermistor will be explained. Figure 8 shows the internal details of the amplifier circuit (12), (111)
, (112) is a power supply terminal to which DC power is applied, and (1
12) side is the ground side. (113) is an amplifier with an input terminal (H3a), a reference voltage input terminal (113b),
It has an output terminal (113c). Input terminal (113a)
The concentration sensor output is input to the rectifier (11). Terminal (111).

(112), an adjustment resistor (114), a reference voltage dividing resistor (115), and a reference voltage fine adjustment resistor (116) are connected in series, and a thermistor (2
6) Connect. The thermistor (26) is connected to the concentration sensor (5
), and its terminals (26a), (26
b) is lead-connected to the amplifier circuit (12). Voltage dividing resistor (
115) The amplifier's reference voltage input terminal (11
3b). The amplification factor adjustment circuit connects the voltage dividing terminal (1
A fine adjustment resistor (118) connected between the reference voltage input terminal (113b) and the reference voltage input terminal (113b)
It consists of a resistor (119) and a capacitor (120) inserted in parallel between the amplifier output terminal (113c) and the amplifier output terminal (113c). A floating voltage suppression resistor (121) is connected between the output terminal (113c) and the terminal (112).

Therefore, the action of the thermistor will be explained. The concentration of the mixed water is determined by measuring the resistance value between the electrodes using the concentration sensor (5), but as the water temperature rises, the resistance value decreases and the signal voltage value given to the amplifier input terminal (113a) increases. rises. Therefore, the output signal voltage value of the amplifier (113) increases, and the concentration value apparently moves upward toward the "dense" side due to the rise in water temperature.

The resistance of the thermistor decreases as the water temperature rises.

The potential at the reference voltage dividing point (115a) increases, and the potential at the amplifier reference voltage input terminal (113b) increases. This increase in the potential of the reference voltage input reduces the potential difference between the input terminal (113a) and the reference voltage input terminal (113b), thereby compensating for the increase in the amplifier input voltage due to the water temperature rise.

Even when the water temperature decreases, compensation can be made in the same way.As described above, the output signal voltage of the amplifier is prevented from fluctuating due to changes in the water temperature.

As mentioned above, if the salt concentration is too high, it will harm the quality of the seaweed product, so it must be managed so as not to exceed the permissible limit.For example, the set standard value Nα is set to 95% of the permissible value Nm, and a control range of plus or minus ( Standard value range width) ΔN is 5%
The upper limit of the management width is Nα+ΔN=100%.

As described above, the control range is determined, and when the concentration falls below the lower limit control value, a seawater supply command is issued, and when the concentration increases and reaches the lower limit control value, a stop command is issued. Additionally, if the concentration exceeds the upper limit control value, a command is issued to supply fresh water.

When the concentration drops to the upper limit control value, a stop command is issued.

Note that the setting reference value Nα is set using a fixed impedance or a variable impedance built into the device, but it is made so that it cannot be adjusted arbitrarily.

How to set the standard value is determined by industry consensus, but generally the allowable value Nm is considered to be around 0.2%, in which case the standard value Nα will be 0.19%, which is the difference between freshwater and seawater. If the ratio of the supply amount in simultaneous supply is determined assuming that the salt content of seawater is 3%, for example, it will be A+B, that is, fresh water and 2'S water = 14:1.

〔Effect of the invention〕

As described above, according to the present invention, the salt concentration of the mixed water in the mixed water adjustment tank is detected by a concentration sensor using a constant voltage oscillation modulation signal, or via a temperature correction circuit based on the temperature of this mixed water. By using a constant voltage as the signal power source for the concentration sensor, it is possible to prevent measurement errors caused by fluctuations in the power supply voltage, and it is possible to use an oscillation modulation signal such as a high frequency signal with balanced polarity as the concentration sensor power source. This prevents measurement errors due to the influence of electrolyzed gas on the electrodes of the concentration sensor, and the temperature correction circuit prevents measurement errors due to temperature fluctuations in the mixed water, making it possible to accurately and continuously measure detected salinity values. can be detected.

If the present invention is applied, when adjusting the salinity concentration of the mixed water of freshwater and seawater supplied to the mixed water adjustment tank (1), it is possible to The salinity can be adjusted quickly by continuously supplying seawater, and even if a large amount of mixed water is used, mixed water with the appropriate salinity can be continuously supplied, and the appropriate salinity obtained in this way can be adjusted continuously. If mixed water with a certain concentration is used for blending with seaweed in the blender (21) and for adjusting the concentration of seaweed in the seaweed mixture in the seaweed mixture stirring tank (22), It can maintain the salt concentration within an appropriate range at all times and can continuously supply a large amount.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a concentration sensor showing an embodiment of the present invention, FIG. 2 is a concentration measurement circuit diagram according to the present invention, FIG. 3(a) is an output waveform at point A in FIG. 2, and FIG. b) is the output waveform at 8 points in Figure 2, Figure 4 is the temperature (water temperature) - water resistance value characteristic diagram, Figure 5 is the concentration, water level control and drive circuit diagram in the mixing water control device, and Figure 6 is the diagram. 7 is a flow sheet of a method and apparatus for adjusting the salinity concentration of a seaweed mixture, and FIG. 8 is a block diagram showing an example of the apparatus for adjusting the salinity concentration of a seaweed mixture. (1); Mixed water adjustment tank (2): Fresh water tank (3):
Seawater tank (4): Stirrer (5): Concentration sensor
(6): Water level sensor (7): Mixed water control device (8
): Power supply circuit (9): Oscillation modulation circuit (10):
If! ! Degree control circuit (11): Rectifier (
12) : Amplifier circuit (13) : Signal discriminator (1
4): Water level control circuit (15): First drive circuit (
16): Second drive circuit (17): Display circuit
(18): Indicator light (19): '1 signal circuit
(20) : FF alarm buzzer (21) : Compounding machine
(22): Seaweed mixture stirring tank (23): Insulating cylinder (24), (25): Electrode (26)
: Temperature correction circuit (pz), (p2), (pa), (p,) : Pump (
vz), (vz): Valve L-L,: Indicator light

Claims (1)

[Claims] 1. Generate a predetermined high frequency signal from an oscillation modulation circuit by receiving a DC constant voltage power supply, adjust the reference level of the output high frequency signal to make a high frequency output signal with positive and negative balance, and convert this output signal into A method for measuring the salinity concentration of water, characterized in that the salt concentration is applied to an electrode of a concentration sensor in water. 2. The method for measuring the salinity concentration of water according to claim 1, characterized in that the output signal of the concentration sensor is outputted through a temperature correction circuit that is operated depending on the water temperature. 3. A power supply circuit that provides a DC constant voltage power supply, an oscillation modulation circuit that receives a DC constant voltage from the power supply circuit and generates a predetermined high frequency signal using an oscillation circuit, and a reference level adjustment that adjusts the reference level of the output signal of the oscillation modulation circuit. 1. An apparatus for measuring salinity of water, comprising: a circuit; and a concentration sensor having a pair of electrodes that are immersed in water to be measured and receive a high-frequency signal that has passed through the adjustment circuit. 4. The water salinity concentration measuring device according to claim 3, wherein the concentration sensor incorporates a temperature correction element for sensing water temperature.