JP2000131213A - Surface tension measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure a maximum bubble pressure with high reliability by measuring a differential pressure between a buffer part in midstream of piping of a large nozzle and a pressure pickup part near a tip part of a small nozzle. SOLUTION: One end of pressure pickup piping 19 is connected to a position within 30 cm from a tip part of a small nozzle 13, while the other end is connected to a differential pressure gauge 5 through a two-way solenoid valve 18. Thereby, though a piping pressure loss caused by a gas flow occurs within the small nozzle 13, a gas flow does not occur within the piping 19 so that no piping pressure loss occurs within the piping 19. A large nozzle 12 used for measuring a mean value of maximum pressures of bubbles has a larger diameter than the small nozzle 13 so that its piping pressure loss is remarkably small. Accordingly, by providing a buffer part 8 in midstream of piping connected to the large nozzle 12, an averaged pressure of the piping is introduced into the differential pressure gauge 5 so that a differential pressure between the averaged pressure and a pressure of the piping 19 is measured by the differential pressure gauge 5. A data processing part 16 takes in an output signal of this differential pressure, converts it into a surface tension, and displays the surface tension.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface tension measuring device used for measuring the surface tension of a liquid. More specifically, the present invention relates to an improvement of a surface tension measuring device using a maximum bubble pressure method, and more particularly to a measuring device suitable for measuring the surface tension of a liquid containing polymer particles, suspended matter, and the like.

[0002]

2. Description of the Related Art Surface tension measurement is indispensable for research and quality control of raw materials and products in the fields of manufacturing paints, coatings, papers, adhesives, fibers, beer, inks, chemicals, and the like. Measurement technology. Conventionally, the following methods are known as methods for measuring the surface tension of a single liquid.

1) Wilhelmy plate method 2) Dunois ring method 3) Static drop method 4) Dripping method 5) Capillary rise method 6) Liquid weight method 7) Maximum bubble pressure method 1) to 6 of the above methods ) Are used in laboratories but not in industrial processes.

Recently, in industrial processes, reactors,
The necessity of measuring the surface tension of a solution in a container or a pipe is increasing. Among the above measurement methods, the only measurement method that may be used for a process is the maximum bubble pressure method of 7). With the maximum bubble pressure method, at least two hollow nozzles having different diameters are provided in the liquid to be measured as shown in a schematic diagram of the measurement principle in FIG. 2, a gas is passed through the nozzle to form bubbles in the liquid,
This is a method for measuring the surface tension by measuring the pressure differential pressure between the nozzles at that time. The surface tension measuring apparatus using the maximum bubble pressure method is disclosed in US Pat. No. 4,416,148 and International Patent Publication WO 9
7/13138 and the like have been proposed.

[0005]

However, in the surface tension measuring device according to the above proposal, the piping distance between the tip of the nozzle of the probe inserted into the reaction vessel or the liquid in the vessel and the differential pressure gauge becomes long, and As shown in (1), there is a problem that an accurate maximum bubble pressure at the nozzle tip cannot be measured. i) The piping pressure loss becomes so large that an accurate maximum bubble pressure cannot be measured. ii) The zero point of the differential pressure gauge shifts due to the pipe pressure loss, and accurate measurement cannot be performed. In view of such a situation, the present invention uses the maximum bubble pressure method to accurately and reliably determine the maximum bubble pressure without being affected even if the distance between the nozzle tip and the differential pressure gauge becomes long. It is an object of the present invention to provide an industrially useful device capable of performing measurement with good quality.

[0006]

That is, the gist of the present invention is as follows.
A surface on which a plurality of nozzles having different diameters are provided in a liquid to be measured, bubbles are formed in the liquid by passing gas through the nozzles, and the surface tension is measured by a maximum bubble pressure method for measuring a pressure differential pressure between the nozzles at that time. In a tension measuring device, a buffer section provided in the middle of a large-diameter nozzle pipe, a pressure extraction section provided near a tip of a small-diameter nozzle, and a differential pressure gauge for measuring a pressure differential pressure between the buffer section and the pressure extraction section Surface tension measuring device, characterized by having:

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 3 shows an overall configuration diagram of a surface tension measuring device using a maximum bubble pressure method used in the present invention. That is, the surface tension measuring device of the present invention comprises (1) a probe, (2) a flow rate switching device, and (3) a data processing unit.
Details of each part will be described below.

(1) Probe section FIG. 4 shows a detailed structure of the probe. The probe section includes a probe mounting flange 11, a metal outer cylinder 17, a large nozzle 12, a small nozzle 13, and a bucket 14. The large nozzle 12 and the small nozzle 13 are each formed of a hollow metal tube or a glass tube having a different diameter, and the nozzle tips are set to have the same depth in the liquid to be measured.
A bucket 14 is provided outside the distal ends of the large nozzle 12 and the small nozzle 13 in order to reduce the influence of the rotation of the liquid to be measured. Large nozzle 1 in bucket 14
2. Except for the tip of the small nozzle 13, a flow hole is provided to facilitate the flow of the liquid to be measured. Large nozzle 1
The diameters of the small nozzle 2 and the small nozzle 13 are not particularly limited as long as the respective diameters are different. For example, the large nozzle has an inner diameter of 2 to 5 mmφ, and the small nozzle has a diameter of 0.5 to 2 mm.
For example, the large nozzle 12 has a diameter of 4 mmφ and the small nozzle 13 has a diameter of 1 mmφ.

A gas is passed through the large nozzle 12 and the small nozzle 13 to form bubbles in the liquid.
And the small nozzle 13 is measured, and the measured value is expressed as a function value of the surface tension as shown in the following equation (I). That is, in the small nozzle 13, the pressure at the time when the bubbles are detached from the nozzle tip is compared with the pressure of the large nozzle 12,
The differential pressure is measured. Also, the dynamic surface tension can be measured by changing the bubble cycle. P = P1-P2 = 2γ (1 / r1-1 / r2) (I) P1, P2: pressure applied to bubble r1, r2: radius of bubble γ: surface tension

(2) Flow switching device Pressure reducing valve 2 The pressure from a gas pressure source 1, for example, nitrogen gas, is reduced to the working pressure. Electronic Mass Flow Meters 3 and 4 The electronic mass flow meters 3 and 4 automatically adjust the mass flow rate of the gas flowing through the nozzles 12 and 13, for example, nitrogen. For setting the gas mass flow rate, a flow rate according to the measurement conditions from the data processing unit 16 can be set.

The differential pressure gauge 5 measures the differential pressure between the nozzles 12 and 13, and its output is connected to the interface 15 and converted into a voltage signal proportional to the differential pressure. Two-way solenoid valves 6, 7 The two-way solenoid valves 6, 7 are valves for opening / closing gas, for example, nitrogen gas, flowing in the lines of the nozzles 12, 13. Buffer Tank 8 The buffer tank 8 is a tank for averaging pressure changes on the nozzle 12 side.

(3) Data processing unit 16 and interface 15 The data processing unit 16 has the following functions. Data capture The differential pressure signal from the differential pressure gauge 5 is read, converted to surface tension, and displayed. The following modes are available in the control device for changing the set value of the mass flow meter and controlling its output sequence.・ Stop mode ・ Calibration mode ・ Measurement mode Automatic measurement and manual measurement

According to the operation of each mode, the operation is performed to automatically perform the valve switching operation under the control of the data processing unit 16. The interface 15 is an electric circuit for converting a signal of the differential pressure gauge 5 into a voltage signal. The above-described method for measuring the pressure difference between the large nozzle 12 and the small nozzle 13 has a problem as described above.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a differential pressure measurement is performed using an apparatus as shown in FIG. That is, the pressure extraction pipe 19 is set within 30 cm from the tip of the small nozzle 13.
And the other end is attached to the differential pressure gauge 5 via the two-way solenoid valve 18. The inner diameter of the pipe 19 may be generally 1 mm or more, preferably 2 to 5 mm.
mm. By doing so, the small nozzle 13
Gas, for example, nitrogen gas flows inside the pipe, causing a pipe pressure loss, whereas there is no gas flow in the pipe 19, so that no pipe pressure loss occurs.

The large nozzle 12 has a small nozzle 1
Since the diameter is larger than 3, the pipe pressure loss is extremely small, and its purpose is to measure the average of the maximum bubble pressure of the bubbles. Therefore, by providing the buffer section 8 in the middle of the pipe connected to the large nozzle 12, the pressure is averaged and introduced into the differential pressure gauge 5, and the differential pressure gauge 5 measures the pressure differential pressure with the pipe 19. Is done.

The operation of the measurement mode automatic measurement in each measurement mode will be described. The gas of the gas pressure source 1, for example, nitrogen gas is set to a predetermined pressure by the pressure reducing valve 2, and the gas adjusted by the mass flowmeters 3 and 4 passes through the two-way solenoid valves 6 and 7 to the large nozzle 12 and the small The solution is blown into the solution to be measured from the nozzle 13 to form a bubble at the nozzle tip. On the other hand, the pressure at the time when the bubble at the tip of the nozzle becomes maximum is measured by the differential pressure gauge 5,
The output signal at this time is taken into the data processing unit 16, converted into surface tension, and displayed.

[0017]

According to the present invention, when measuring the maximum bubble pressure method, even if the distance between the nozzle tip and the differential pressure gauge becomes long, the maximum bubble pressure can be accurately and reliably measured without being affected by the distance. It is an industrially useful surface tension measurement device that can measure well.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a surface tension measuring device of the present invention.

FIG. 2 is a schematic diagram showing the principle of surface tension measurement by the maximum bubble pressure method.

FIG. 3 is an explanatory diagram of a surface tension measuring device using a maximum bubble pressure method.

FIG. 4 is an explanatory view showing the structure of a probe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas pressure source 2 Pressure reducing valve 3 Electronic mass flow meter 4 Electronic mass flow meter 5 Differential pressure gauge 6 Two-way solenoid valve 7 Two-way solenoid valve 8 Buffer tank 9 Metal piping 10 Metal piping 11 Probe mounting flange 12 Large nozzle 13 Small Nozzle 14 Bucket 15 Interface 16 Data processing device 17 Metal outer cylinder 18 Two-way solenoid valve 19 Piping

Claims (1)

[Claims] 1. A plurality of nozzles having different diameters are installed in a liquid to be measured, bubbles are formed in the liquid by passing a gas through the nozzles, and a maximum bubble pressure method is used to measure a pressure differential pressure between the nozzles at that time. In a surface tension measuring device for measuring surface tension, a buffer section provided in the middle of a large-diameter nozzle pipe, a pressure extraction section provided near the tip of a small-diameter nozzle, and a pressure difference between the buffer section and the pressure extraction section A surface tension measuring device comprising a differential pressure gauge for measuring pressure.