JPS63124932A - Method and device for measuring fine particle in air-bubble containing liquid - Google Patents

Abstract

PURPOSE:To accurately count fine particles in liquid which contains air bubbles by raising the pressure of the liquid to be measured so that gas dissolved in the liquid is more than gas produced by the decomposition of the liquid to be measured. CONSTITUTION:An inlet valve 2 and an outlet valve 4 are closed and a by-pass valve 6 is opened to supply the liquid to be measured through by-pass piping 7. The discharge valve 13 of a pressurized container 10 is closed and the pressure valve 11 is opened to inject pressure liquid into the pressurized container 10. At this time the pressure application speed of the pressure liquid is so controlled that the increase speed of the amount dissolved gas increasing with the pressure and the decrease speed of air bubble capacity are faster than the production speed of gas produced by the decomposition of materials in the liquid to be measured, thereby counting particles by using light or an ultrasonic wave. Consequently, fine particles in the liquid are measured securely and smoothly without detecting the air bubbles.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for measuring the number of fine solid particles contained as impurities in a liquid substance.

[Conventional technology]

In recent years, high-purity liquid chemicals and ultrapure water are required in the electronic industry such as LSI manufacturing processes and IPt in the pharmaceutical industry, and the measurement of the number of fine particles in these liquids has become important. ing.

For example, in the LSI manufacturing process in the electronics industry, the presence of fine particles (solid particles) in the ultrapure water and liquid chemicals used increases the incidence of defective products. Water and liquid chemicals are required. Note that the term "fine solid particles" as used herein refers to a particle size of 01 to 10 μm, and "high purity" refers to a liquid containing several to several thousand solid particles in 1 ml of liquid.

When refining or using such high-purity liquid substances, it is necessary to constantly measure the number of fine particles contained as impurities.

By the way, there are two methods for measuring fine particles in liquid, depending on the person: a direct inspection method and a method using a particle counter.

(a) Direct inspection method In this method, liquid is passed through a membrane filter, fine particles are collected on the membrane filter, and the particles are observed using an optical or electron microscope. For a given substance, each particle size is counted, and then the calculated value is converted into the number of fine particles per unit liquid hanging from the area of the membrane filter, the area of the field of view of the microscope, and the amount of filtrate. This method is considered to be the most reliable as it identifies and counts fine particles.

However, in this method, the temperature is
There are many error factors such as the contamination of fine particles, fine particles added to the membrane filter itself, and individual differences in the person making the measurement. In order to reduce these errors, it is necessary to filter a large amount of liquid, but with expensive liquids or liquids with high viscosity, it is not possible to perform many filtrations, and it is necessary to perform highly refined measurements. It is not possible.

Furthermore, since the measurement is performed by wobbling the liquid, online, real-time measurement is not possible, and it cannot be used as a line monitor in a liquid purification device or at a location where liquid is used.

(b) Method using a particle counter This method involves passing light or ultrasonic waves through a liquid and automatically measuring the particles electrically.The following methods are available.

b) Light blocking method This is a method in which parallel light is passed through a liquid and light blocking by fine particles is detected as a decrease in received light^1.The minimum measurable fine particle diameter is 1 μm, which is required in the LSI manufacturing industry. It can be used to measure fine particles (0.1 to 0.2 μTrL).

Mouth) Laser light scattering method A method in which a laser beam is passed through a liquid and the light scattered by fine particles in the liquid is electrically detected and measured.The minimum measurable fine particle diameter is 0.5 μm. However, one that can measure 0.1 μm has been developed.

c) Ultrasonic method This is a method in which ultrasonic waves are emitted into a liquid, and the ultrasonic echoes reflected by minute particles in the liquid are received and counted.

The above-mentioned method using a particle counter allows measurement online and in real time, and is therefore often used as a line monitor in liquid purification equipment or locations where liquid is used.

[Problem that the invention seeks to solve]

However, in the conventional measurement method using a particle counter, all objects that reflect light or ultrasonic waves are detected, so the direct inspection method has a problem in that the number of objects to be measured is 81. . especially,
In the case of a liquid containing bubbles, even the bubbles are counted, resulting in an error in the measured value and, therefore, it is not possible to perform accurate measurements.

Therefore, in order to prevent the air bubbles in the liquid from flowing into the measuring part of the particle counter, some devices are known that have a bubble separating part or the like installed at the front stage of the particulate counter. For example, in the case of hydrogen peroxide, nitric acid, etc.
While light or ultrasonic waves are irradiated for a certain period of time (for example, 20 seconds) to stabilize counting, bubbles are formed in the liquid, so there is a problem that the number of microparticles cannot be accurately counted to 1. there were.

The present invention has been made in view of the above circumstances, and its purpose is to reliably eliminate fine particles in liquids that contain bubbles, particularly in liquids that generate bubbles when substances in the liquid decompose. A method and equipment for measuring fine particles in a bubble-containing liquid that can be measured smoothly and with good measurement accuracy. Our goal is to provide the following.

[Means for solving problems]

In order to achieve the above object, the method of the present invention measures fine particles using light or ultrasonic waves while increasing the pressure of the liquid to be measured stepwise or continuously. While measuring fine particles, the pressure of the liquid to be measured is adjusted so that the amount of dissolved gas that increases due to the rise in pressure of the liquid to be measured is greater than the amount of gas generated in the liquid to be measured. . It is desirable to once reduce the pressure of the liquid to be measured before increasing the pressure of the liquid to be measured.

Further, the first device of the present invention includes a measurement container having an inlet and an outlet and an open top for containing a liquid to be measured, and a measurement container sealed in a sealed state. The pressurized container is equipped with a pressure pipe for supplying pressurized fluid.

Furthermore, in the second device of the present invention, the sealed storage tank containing the liquid to be measured is provided with liquid inlet and outlet pipes at its bottom, and connected to a pressure regulating gas pipe through which gas flows at the top. It is preferable that a particle counter is provided at the lowest part of the liquid outlet pipe, and that a liquid level adjustment tank for setting the liquid level of the liquid to be measured is connected.

[For production]

In the method and apparatus for measuring fine particles in a liquid containing bubbles of the present invention, when measuring fine particles in a liquid to be measured using light or ultrasonic waves, the solution of gas Fl'i'A
The generation of bubbles in the liquid is prevented by increasing the pressure of the liquid to be measured stepwise or continuously so that t is larger than the amount of gas generated due to decomposition of substances in the liquid to be measured. and compress the bubble volume to reduce the bubble particle size, prevent the bubbles from being detected by a particle counter, and improve measurement accuracy.

〔Example〕

Hereinafter, an actual IM example of the present invention will be explained based on FIGS. 1 to 6.

1 and 2 show an example of the fine particle measuring device of the present invention, with FIG. 1 being a plan sectional view and FIG. 2 being an elevational sectional view. In these figures, numeral 1 indicates hydrogen peroxide solution,
This is a measurement container that stores a liquid to be measured such as nitric acid, and this measurement container 1 includes an inlet pipe 3 having a large mouth valve 2 and an outlet valve 4
and the outlet pipe 5 are connected to each other, and the upper part of the measuring part 31 is open. A bypass pipe 7 having a bypass valve 6 is connected between the inlet pipe 3 on the upstream side of the large mouth valve 2 and the outlet pipe 5 on the downstream side of the outlet valve 4. Furthermore, a pair of laser oscillating sections 8 and a laser receiving section 9 are disposed facing each other on the side of the measuring container 1 with the measuring container 1 in between. Fine particles are counted by Furthermore, this measurement container 1 is housed inside a pressurized container 10, and this pressurized container 10
A pressure pipe 12 having a pressure valve 11 and a discharge pipe 14 connected to a discharge valve 13 are connected to the bottom of the pipe. This pressurized piping 12 is for supplying pressurized fluid into the pressurized container 10, and the pressurized fluid may be the same liquid as the liquid to be measured, ultrapure water, clean nitrogen gas, or other fluid. Use a dust-free gas. In addition, when using a liquid as the pressurized fluid, as shown in FIG. A gas inlet pipe 16 having a gas population valve 15 for supplying gas, and a gas inlet pipe 16 for use when the amount of gas in the pressurized container 10 becomes excessive.
The gas vent valve 17 is connected to the right gas outlet pipe 18.

Further, in FIG. 2, reference numerals j319 and 20 indicate a pressure gauge and a pressure regulator installed in the inlet pipe 3 and the discharge pipe 14, respectively. Furthermore, as the pressurized fluid, it is most desirable to use the same liquid as the liquid to be measured in order to prevent contamination of the liquid to be measured.

Next, a case will be described in which an example of the method of the present invention is implemented using the fine particle measuring device configured as described above.

Normally, when measurement is not being performed, the liquid to be measured is transferred to the inlet piping 3, the artificial valve 2, the measuring container 1, the outlet valve 4,
It is made to flow to the outlet pipe 5 so that the liquid to be measured in the measurement container 1 is constantly replaced.

Next, when measuring fine particles in the liquid to be measured, the inlet valve 2 and the outlet valve 4 are closed, the bypass valve 6 is opened, and the liquid to be measured is allowed to flow through the bypass pipe 7.

In this state, close the discharge valve 13 of the pressurized container 10,
Pressure valve 11 is opened to inject pressurized fluid into pressurized container 10 . In this case, if a liquid is used as the pressurized fluid,
Operate so that the liquid level does not reach the upper end of the measuring container 1. In addition, the rate of pressurization by the pressurized fluid is faster than the rate of gas generation due to decomposition of the substance in the liquid to be measured in the measurement container 1, and the rate of increase in the amount of gas dissolved and the volume of bubbles that increase due to pressurization. Control is performed to increase the rate of decrease. To explain this state with reference to FIG. 3, the pressure within the measurement container 1 increases with time and reaches the maximum usable pressure at time t2. Along with this, the amount of dissolved gas increases until time t3, and then maintains a constant value, so at time t
From o to tl, the amount of gas dissolved exceeds the amount of gas generated. Therefore, by performing the measurement during this period, no bubbles will be generated in the liquid to be measured, and an accurate 31 count can be obtained.

After measuring fine particles in the liquid to be measured in this way, the pressure valve 11 and the discharge valve 13 are opened to return the pressure inside the pressure vessel 10 to the pressure before pressurization and discharge the liquid. Valve 13
Close. Next, the artificial valve 2 and the outlet valve 4 are closed, the bypass valve 6 is closed, and the liquid to be measured is allowed to flow into the measurement container 1. In this case, if the pressure inside the measurement container 1 (pressurized container 10) decreases too much due to the opening/closing operation of the outlet valve 13, there is a risk that the liquid to be measured may seep out from inside the measurement container 1.
The pressure in the artificial pipe 3 is measured by a pressure gauge 19''c, and the opening and closing of the discharge valve 13 is controlled by pressure 1!Ii[+20] so that the pressure in the measurement container 1 becomes the same as that in the pressure gauge 19''c.

An example implemented to confirm the above effects will be described based on FIG. 4. In this example, nitrogen gas is used as the pressurized fluid, and 31%
Semiconductor T-chestnut grade hydrogen peroxide solution is distributed, and the number of dust particles in this liquid is determined by He-Ne (helium-neon).
Measured by laser. The measurement results are shown in Table 1.

In addition, 21 in the figure is a pressure cylinder.

Table 1 As is clear from Table 1, pressure 3Kg/cri, 5K
When pressurized to g/ci, no air bubbles are generated within the time required for measurement (approximately 20 seconds) and the number of dust particles can be accurately measured, whereas when no pressure is applied, or when the pressure I K'
If pressurized to j/ci or I K! J/
When measuring after leaving the CTI under pressure for 1 minute, the number of detected dust increased, indicating that not only impurities (solid particles) but also air bubbles were counted.

Moreover, FIG. 5 shows another example of the fine particle measuring device of the present invention, and the reference numeral 30 in the figure is an inlet head tank;
An L-shaped inlet pipe 31 and a U-shaped pressurizing pipe 32 are connected to the bottom of the inlet head tank 30, respectively. An outlet head tank 33 is connected to this pressurizing pipe 32, and a pair of emitting part 34 and a wave receiving part 35 are connected to the lowest part of the pressurizing pipe 32, and a laser or A particle counter 36 that counts fine particles using ultrasonic waves is installed. Further, an outlet head tank piping 37 is connected to the outlet head tank 33 with its upper end inserted into the interior thereof, and a gas separation tank 38 is connected to the lower end of the outlet head tank piping 37. ing. An outlet pipe 39 for transferring the liquid to be measured to the point of use is connected to the gas separation tank 38, and a gas vent pipe 40 is arranged between the gas separation tank 38 and the outlet head tank 33. There is. Further, a gas pressure equalization pipe 41 is connected to the top of both head tanks 30, and a gas inlet pipe 44 is connected to both ends of the gas pressure equalization pipe 41 via a gas population valve 42 and a gas outlet valve 43, respectively. and a gas outlet pipe 45 are connected.

When measuring fine particles in a liquid to be measured using the fine particle measuring device configured as described above, the liquid to be measured is supplied to the inlet head tank 30 via the inlet piping 31. As a result, the liquid to be measured that has entered the inlet head tank 30 flows into the pressurizing pipe 32 after separating the bubbles contained therein. Then, at the bottom of the pressurizing pipe 32, the liquid to be measured is pressurized to the maximum, and the number of fine particles is continuously measured by the fine particle counter 36 in a state in which no air bubbles are contained inside.

The liquid to be measured then rises and enters the outlet head tank 33 , overflows and is introduced into the gas separation tank 38 via the outlet head tank piping 37 . and,
Here, the liquid to be measured from which the gas has been separated is supplied to the point of use via the outlet pipe 39.

Furthermore, FIG. 6 shows another example of the fine particle measuring device of the present invention, and this fine particle measuring device has a head tank 5.
An inlet pipe 51 and a pressurizing pipe 52 are connected to the bottom of the head. A gas exhaust pipe (suction pipe) 56 is connected to the top of the tank 50. In addition, in the figure, 5
7.58 is a limit switch for controlling the liquid level of the liquid to be measured in the head tank 50.

In the fine particle measuring device configured as described above, the liquid to be measured flows from the inlet pipe 51 to the head tank 5.
Introduced within 0. In this case, inside the head tank 50,
By suctioning gas through the gas discharge pipe 56, a reduced pressure state is maintained, thereby separating and removing air bubbles in the liquid to be measured.

Next, the liquid to be measured from which air bubbles have been separated and removed is supplied to the point of use after the number of fine particles is measured at the lowest part of the pressurizing pipe 52. Therefore, the liquid to be measured is most pressurized,
The number of fine particles can be counted continuously in the absence of air bubbles.

In the above embodiment, the higher the pressure when pressurizing the liquid to be measured, the less bubbles will be generated. Pressure pressure rise speed and maximum operating pressure are as follows:
As shown in FIG. 3, it may be selected as appropriate within a range in which bubbles are not generated within the measurement time (t+-to).

〔Effect of the invention〕

As explained above, the present invention provides a method for measuring fine particles in a liquid to be measured using light or ultrahigh waves, etc., when the amount of dissolved gas is generated due to decomposition of a substance in the liquid to be measured. Since the pressure of the liquid to be measured is increased stepwise or continuously so that it becomes greater than the gas h1,
By suppressing the generation of air bubbles in the liquid and compressing the air bubble volume to reduce the air bubble particle size and prevent air bubbles from being detected by a particle counter, it is possible to prevent air bubbles from forming in liquids, especially liquids containing air bubbles. It is possible to reliably and smoothly measure fine particles in liquids, where substances decompose and generate bubbles, improve measurement accuracy, and offer an excellent ability to perform online and real-time measurements. have an effect.

[Brief explanation of the drawing]

1 and 2 show an example of the fine particle measuring device of the present invention, in which FIG. 1 is a plan sectional view, FIG. 2 is an elevational sectional view,
Fig. 3 is a characteristic diagram explaining the present invention in detail, Fig. 4 is a schematic configuration diagram showing an example carried out to confirm the effects of the present invention, and Fig. 5 is another example of the fine particle measuring device of the present invention. FIG. 6 is a schematic diagram showing another example of the fine particle measuring device of the present invention. 1...Measurement container, 2...Inlet valve, 3.
...Inlet piping, 4...Outlet valve, 5...
...Outlet piping, 8...Laser oscillation section, 9.
...Laser light receiving part, 10 ... Pressure vessel, 12 ... Pressure piping, 30 ... Inlet head tank, 31 ... Inlet Piping, 32...
... Pressure piping, 33 ... Outlet head tank, 3
6...Particle counter, 41...Gas pressure equalization pipe, 50...Head tank, 51...
...Inlet piping, 52... Pressure piping, 55...
...Particle counter, 56... Gas discharge pipe (suction pipe).

Claims (5)

[Claims] (1) In a method for measuring fine particles in a bubble-containing liquid in which the number of fine particles in a liquid to be measured is measured using light or ultrasound, the pressure of the liquid to be measured is increased stepwise or continuously. While measuring fine particles in the liquid to be measured, the amount of dissolved gas that increases due to the upper pressure limit of the liquid to be measured is generated due to decomposition of substances in the liquid to be measured. A method for measuring fine particles in a bubble-containing liquid, characterized in that the pressure of the liquid to be measured is adjusted so that the pressure of the liquid to be measured is greater than the amount of gas. (2) Measurement of fine particles in a bubble-containing liquid according to claim 1, wherein the pressure of the liquid to be measured is once reduced before increasing the pressure of the liquid to be measured. Method. (3) In a device for measuring fine particles in a bubble-containing liquid that includes a built-in particle counter that counts fine particles in a liquid to be measured using light or ultrasound, there is an inlet and an outlet for containing the liquid to be measured. and a measuring container with an open top, and a pressurized container that seals the measuring container, and the pressurized container is provided with a pressure pipe for supplying pressurized fluid. A device for measuring fine particles in a bubble-containing liquid. (4) In a device for measuring fine particles in a bubble-containing liquid that includes a built-in particle counter that counts fine particles in a liquid to be measured using light or ultrasonic waves, the sealed storage tank containing the liquid to be measured, A bubble-containing liquid comprising a liquid inlet/outlet pipe provided at the bottom thereof and a pressure regulating gas pipe connected to the upper part thereof for circulating gas, and the above-mentioned particle counter is provided at the lowest part of the liquid inlet/outlet pipe. Fine particle measuring device inside. (5) A device for measuring fine particles in a bubble-containing liquid according to claim 4, characterized in that a liquid level adjustment tank for setting the liquid level of the liquid to be measured is connected to the liquid outlet pipe. .