JPH0772105A - Detector for solution concentration - Google Patents

Abstract

PURPOSE:To provide a solution concentration detector of high accuracy and reliability, and capable of continuously controlling a concentration without generating clogging, etc. CONSTITUTION:The solution concentration detector comprises a main body 10 for covering a solution surface 2 and forming a air-sealed space, and also for making up the correlation between concentrations in the liquid phase and in the gas phase, of a solute within the air-sealed space, a gas agitating means 20 for agitating the atmospheric gas 3 within the main body 10, and a gas concentration detecting means 30 for detecting the concentration in the atmospheric gas 3 agitated by the gas agitating means 20, and the concentration in the liquid phase is detected from the concentration in the gas phase detected by the gas concentration detecting means 30 on the basis of the correlation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solution concentration detecting device, and more particularly to a solution concentration detecting device capable of continuously controlling the concentration of a solution without sampling.

[0002]

2. Description of the Related Art Generally, for measuring the concentration of solute in a solution, for example, the concentration of alcohol in an aqueous alcohol solution,
A method using a hydrometer is known. However, this method is difficult to (a) continuously measure the concentration. (b)
If there is a solvent other than water, it is necessary to remove the water. (c) Temperature control is required. There are various problems. In addition to the above method, there is a method using gas chromatography (FID), but this method has a problem that the apparatus is very expensive, the analysis takes time, and continuous measurement is difficult.

Both of the above-mentioned methods are suitable for performing concentration control while sampling in a timely manner, but have the disadvantage that continuous concentration control is difficult. On the other hand, a solution concentration detecting device shown in FIG. 7 is known as a method of continuously controlling the concentration. This solution concentration detecting device is provided with an alcohol permeable film 61 at the tip, a probe 62 having a sensor built therein, and a main body 63 connected to the probe 62 and having an arithmetic control unit. Then, when the sensor output is input to the main body 63, the arithmetic control unit calculates the alcohol concentration in the solution based on the sensor output, and displays this value on the LCD 64 or the like.

[0004]

As described above, there is an apparatus using a permeable membrane as a solution concentration detecting apparatus capable of continuous concentration control. However, this solution concentration detecting device has a major problem that it is necessary to periodically replace the permeable membrane, and the permeable membrane often causes clogging, which makes continuous concentration control impossible.

Therefore, an object of the present invention is to provide a highly accurate and reliable solution concentration detecting device which does not require sampling and which does not cause clogging and which enables continuous concentration control.

[0006]

In order to achieve the above object, the present invention has an opening, and the opening is closed with a solution to form an airtight space containing an atmospheric gas in a liquid phase of a solute in the solution. A main body that forms a predetermined correlation between the concentration and the concentration in the gas phase, a gas stirring unit that stirs the atmospheric gas in the main unit, and the gas phase in the atmospheric gas that is stirred by the gas stirring unit A gas concentration detecting means for detecting the concentration, and a concentration in the liquid phase is detected from the concentration in the gas phase detected by the gas concentration detecting means based on the correlation. .

[0007]

In the present invention, since the main body having the opening and closing the opening with the solution to form the airtight space containing the atmospheric gas, the concentration of the solute in the solution in the liquid phase and the evaporation concentration in the main body are provided. It is possible to constantly maintain a predetermined correlation with and. Further, since the atmospheric gas in the main body is agitated by the gas agitating means, the evaporation concentration can be reached quickly. Here, the evaporation concentration is the concentration in the vapor phase when the concentration in the liquid phase and the concentration in the vapor phase of the solute are at or near the equilibrium state at ambient temperature.

[0008] Therefore, by always providing the main body, the evaporation concentration in the main body can be made to correspond to the concentration in the liquid phase without sampling, and even if the concentration of the solution changes, by stirring, Since the vapor concentration corresponding to the change is immediately responded, the continuous concentration control with high accuracy and reliability can be performed.

[0009]

The present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an explanatory perspective view showing an appearance and a control system of an embodiment of the present invention, FIG. 2 is an explanatory front view showing the same configuration and control system, and FIG. 3 is a liquid phase concentration and a gas phase concentration. And FIG. 4 is an explanatory diagram showing the relationship between temperature, concentration in gas phase and concentration in liquid phase, and FIG. 5 is a relationship diagram between temperature after correction and concentration in gas phase. Explanatory diagram, Figure 6
Is an explanatory diagram of response speed characteristics, and FIG. 7 is a front view explanatory diagram of a conventional example.

A solution concentration detecting device E according to an embodiment of the present invention has an opening 14, and the opening 14 is closed with a solution 1 to form an airtight space containing an atmospheric gas 3 to form a liquid phase of a solute in the solution 1. A main body 10 that forms a predetermined correlation between the medium concentration and the gas phase concentration, a gas stirring unit 20 that stirs the atmosphere gas 3 in the main unit 10, and an atmosphere that is stirred by the gas stirring unit 20. The gas concentration detecting means 30 for detecting the concentration in the gas phase of the gas 3 is provided, and the concentration in the liquid phase is detected from the concentration in the gas phase detected by the gas concentration detecting means 30 based on the correlation. It was done like this.

Therefore, since a permeable membrane or the like is not used, there is no possibility of inconvenience such as interruption of measurement due to unexpected clogging, and the reliability of continuous concentration control can be greatly improved. .

The structure and operation of this embodiment will be described in detail below. In this example, the solution 1 is an aqueous solution of ethyl alcohol consisting of ethyl alcohol as a solute and water as a solvent. The atmospheric gas 3 that covers the entire liquid surface 2 is air.

In the present embodiment, a main body 10 floating on the liquid surface 2,
It is composed of a gas stirring means 20 for stirring the air 3 in and out of the main body 10 by flowing it in and out, and a gas concentration detecting means 30 for detecting the gas phase concentration of the air 3 in the main body stirred by this means 20. .

First, the upper end 12 of the main body 10 is closed,
The lower end portion 13 has a cylindrical airtight member 11 made of resin and having an opening 14. In addition, a float 15 is attached to the midway of the airtight member 11 so as to surround the outside and the position of the float 15 can be adjusted.
Is attached. With this configuration, when the main body 10 is floated in the solution 1, the main body 10 is submerged in the liquid by the stable weight 16 up to the position of the float 15, and is held in an upright and stable posture by the stable weight 16. Therefore, by adjusting the position of the float 15, by adjusting the depth of sinking, so that it is possible to adjust the ratio of the volumes of the gas phase V _a of the liquid phase V _l of the body 10 as appropriate It has become. Since the body 10 of the above-described structure, when floated in a solution 1, by adjusting the volume of the gas phase V _a, the liquid phase concentration and the gas phase concentration of the solute (evaporation concentration)
It is possible to set a predetermined correlation between and.

The gas stirring means 20 comprises a pump 21, an outflow passage 22 connected to the suction side of the pump 21, and an inflow passage 25 connected to the discharge side of the pump 21. One end of the outflow passage 22 is connected to the pump 21 via a flexible tube 23, and the other end of the outflow passage 22 is at the upper end 1 of the main body 10.
2 is attached to the main body 10 by airtightly passing through the main body 10.
It has an opening inside. Further, a flow rate control valve 24 is provided in the middle part.

Further, one end of the inflow passage 25 is the pump 21.
Is connected to the discharge side via a flexible tube 26. An inflow path 25 extending from this connecting portion penetrates the upper end 12 of the main body 10 in an airtight manner, is attached to the main body 10, and extends through the main body 10 into the solution 1 near the opening 14,
A filter unit 27 is provided on the other end side below the liquid surface 2. The filtration unit 27 has a diameter of 100 μm to 300 μm.
A filter plate 27b having a large number of μm through holes 27a is provided. 28 is a flow control valve.

When the pump 21 is operated, the main body 1
The air 3 in 0 is sucked out together with the vapor of ethyl alcohol, which is a solute, and flows out, reaches the filtering unit 27 through the outflow passage 22, the pump 21, and the inflow passage 25, and is ejected as bubbles 27c to eject the solution 1 It is discharged into the main body 10 with stirring.

The gas concentration detecting means 30 is a gas sensor 3
1, a temperature sensor 33 and a control device 35. The gas sensor 31, which is a catalytic combustion type gas sensor, is mounted in the main body 10 and detects the concentration of ethyl alcohol vapor in the vapor phase in the main body 10. The temperature sensor 33 is provided in the main body 10 near the gas sensor 31, and detects the temperature of the air 3 near the gas sensor 31 (sometimes referred to as ambient temperature).

The control device 35 is connected to the gas sensor output detection circuit 36 to which the gas sensor 31 is connected, the temperature correction circuit 37 connected to the gas sensor output detection circuit 36 and the temperature sensor 33, and the temperature correction circuit. Three
7, a display circuit 39, and an arithmetic control circuit 38 to which a pump drive circuit 40 is connected.

The gas sensor output detection circuit 36 drives the gas sensor 31, detects the sensor output to detect the gas phase concentration of ethyl alcohol, and outputs this concentration to the temperature correction circuit 37 as a gas phase concentration signal. The temperature correction circuit 37 detects the temperature of the atmospheric gas 3 in the main body 10 based on the sensor output from the temperature sensor 33, and corrects the temperature of the gas phase concentration of alcohol input from the gas sensor output detection circuit 36 ( (See FIG. 5) The corrected gas phase concentration signal is output to the arithmetic and control circuit 38.

The arithmetic control circuit 38 is a control unit (not shown),
A liquid phase concentration of ethyl alcohol in the solution 1 is provided by using a data stored in advance in the storage unit based on a corrected gas phase concentration signal input from the temperature correction circuit 37, which includes a calculation unit, a storage unit, and the like. Is calculated and stored, and is output to the display circuit 39 as a liquid phase concentration signal of ethyl alcohol. The arithmetic control circuit 38 also drives the pump 21 via the pump drive circuit 40. Although not shown, the display circuit 39 includes, for example, a display device composed of an LCD, a continuous recording device using recording paper as shown in FIG. 6, and the like, and based on the input liquidus concentration signal of alcohol. Display solution concentration and record at the same time.

The overall operation of this embodiment will be described. When the pump 21 operates and the flow of the air 3 as the atmospheric gas is in a steady state, the air 3 in the main body 10 passes through the outflow passage 22.
Together with the vapor of ethyl alcohol flow out at a constant outflow rate, reach the filtering section 27 through the inflow path 25, and are ejected into the solution 1 as bubbles, and the solution 1 is stirred in the main body 10 again. Is released to. Under such an operation, the outputs of the gas concentration sensor 31 and the temperature sensor 33 are input to the control device 35, the input values are arithmetically processed, and the liquid phase concentration of ethyl alcohol is calculated and stored in the storage unit. With
The solution concentration is displayed on the LCD of the display circuit 39 and is simultaneously recorded in the recording device.

Next, the operation of each part will be described in more detail. When the inner volume of the main body 10 is 1000 ml and the vapor phase volume V _a is 900 ml, the concentration of ethyl alcohol in the liquid phase and the concentration in the gas phase are set. The correlation with (evaporation concentration) is as shown in FIG. In the main line diagram, the horizontal axis represents the concentration of ethyl alcohol in the liquid phase in%, and the vertical axis represents the concentration in the gas phase in%. The ambient temperature is 20 ° C. As shown, a high correlation is maintained.

Further, the above correlation is at an ambient temperature of 20 ° C., but when the ambient temperature changes, the above relation changes. This is because the evaporation concentration of ethyl alcohol changes depending on the ambient temperature. FIG. 4 is a graph showing the relationship between the ambient temperature and the concentrations of ethyl alcohol in the gas phase and liquid phase, where the horizontal axis is the ambient temperature in ° C. and the vertical axis is the gas phase concentration in%. a is a case where the concentration of ethyl alcohol in the liquid phase is 5.0%, and curve b has a concentration of 10.
The curve c is the case where the same concentration is 15.0%, and the curve d is the case where the same concentration is 20.0%.

As shown in the figure, the concentration in the vapor phase (evaporation concentration) changes with temperature for the same concentration in the liquid phase, but by correcting the temperature, it should be corrected to a constant value as shown in FIG. You can In this figure, the horizontal axis is the ambient temperature in ° C,
The vertical axis represents the concentration in the gas phase in%. The curve e shows the case where the concentration of ethyl alcohol in the liquid phase is 5.0%, and the curve f shows the case where the concentration is 10.0%. , Curve g is for the same concentration of 15.0%. For the same concentration in the liquid phase, the values are almost the same regardless of the temperature. Figure 6
In the diagram showing the response speed of this example, the horizontal axis represents time in minutes and the vertical axis represents concentration in the gas phase in%. The case where the concentration of the aqueous ethyl alcohol solution is 20% and the temperature is ambient is shown. A few seconds after the start of operation, a steady state is reached and the evaporation concentration is obtained.

When the main body forming the airtight space is floated in the solution as in the present embodiment, even if the liquid level changes, it can follow this and keep the gas phase volume constant at all times. Because it is possible, stable measurement is possible. Further, since the bubbles are formed, the solution is stirred, and the change in the concentration can be quickly followed.

In the present embodiment, an ethyl alcohol aqueous solution has been described as an example, but the present invention is not limited to this aqueous solution and may be a solution of another solvent or solute in which the present invention can be carried out. Further, the main body may be fixed and provided without floating.

[0029]

As described above in detail, according to the present invention, since the main body having the opening and closing the opening with the solution to form the airtight space containing the atmospheric gas, the liquid of the solute in the solution is provided. A predetermined correlation can always be formed and maintained between the in-phase concentration and the evaporation concentration in the main body. Further, since the atmospheric gas in the main body is agitated by the gas agitating means, the evaporation concentration can be reached quickly. Here, the evaporation concentration refers to the concentration in the gas phase when the concentration in the liquid phase and the concentration in the gas phase of the solute are in an equilibrium state or a state close thereto at ambient temperature.

Therefore, by always providing the above-mentioned main body, the evaporation concentration in the main body can be made to correspond to the concentration in the liquid phase without sampling, and even if the concentration of the solution changes, by stirring, Since the vapor concentration corresponding to the change is immediately responded, the continuous concentration control with high accuracy and reliability can be performed.

[Brief description of drawings]

FIG. 1 is an explanatory perspective view showing an appearance and a control system of an embodiment of the present invention.

FIG. 2 is an explanatory front view showing the same configuration and control system.

FIG. 3 is a diagram for explaining the correlation between the liquid phase concentration and the gas phase concentration.

FIG. 4 is an explanatory diagram showing the relationship among ambient temperature, gas phase concentration and liquid phase concentration.

FIG. 5 is an explanatory diagram showing a relationship between the ambient temperature and the concentration in the gas phase after the correction.

FIG. 6 is an explanatory diagram of response speed characteristics.

FIG. 7 is a front view explanatory diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Solution 3 Atmosphere gas (air) 10 Main body 14 Opening 15 Float 20 Gas stirring means 30 Gas concentration detection means

Claims (3)

[Claims] 1. An opening is formed, and the opening is closed with a solution to form an airtight space containing an atmospheric gas, and a predetermined correlation is formed between the concentration in the liquid phase and the concentration in the gas phase of the solute in the solution. The main body, a gas stirring means for stirring the atmospheric gas in the main body, and a gas concentration detecting means for detecting the concentration in the gas phase in the atmospheric gas stirred by the gas stirring means. A solution concentration detector characterized in that the concentration in the liquid phase is detected from the concentration in the gas phase detected by the detecting means based on the correlation. 2. The solution concentration detecting device according to claim 1, wherein the main body has a float and floats in the solution. 3. The gas stirring means is characterized in that the atmospheric gas in the main body is caused to flow out from one side and is circulated from the other side, and at the time of the inflow, the atmospheric gas is ejected into the solution in the form of bubbles. Alternatively, the solution concentration detection device according to claim 2.