JPH0344652B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method and apparatus for measuring impurities in a liquid, and in particular, to a method and an apparatus for measuring impurities in a liquid, and in particular to measuring the particle size and number of fine particles in a liquid, or the amount of salts in a liquid. This invention relates to a method and device suitable for measurement.

[Background of the invention]

Conventionally, among the devices that directly measure the particle size and number of fine particles in liquid online, the laser scattering method is capable of measuring the smallest particle size, but the smallest particle size that can be measured is about 0.5μ, and it is The following particle size measurements are not possible. On the other hand, it is well known that airborne particle measuring instruments that use laser scattered light can measure particles as small as 0.1μ in the air.

By the way, a standard particle aerosol generator using polystyrene latex spherical standard particles manufactured by Dow Chemical Company for instrument calibration of airborne particulate measuring instruments (for example, Otsuka et al., "Measurement of Particulate Matter in Pollution Measurement", Hitachi Review) vol56, No.11 (1974-11),
(See page 1089), but even if such devices and equipment are combined, particle size can be measured, but particle size distribution and number cannot be measured. The reason for this will be explained using the device flow of a conventional aerosol generator shown in FIG. Since the purpose of this aerosol generator is to calibrate an airborne particle measuring device, it is sufficient to vaporize a liquid containing standard particles of known particle size and suspend the particles in a gas. In this device, first, a liquid 100 in which standard particles are suspended is poured into an atomizer 1.
A part of the mist 110 is mixed with the clean gas 120 of the diluter 20, and then externally heated using the heater 35 in the vaporizer 30 to vaporize the mist. The gas 130 in which particles in the liquid are suspended in the gas is sent to the airborne particle measuring device 40. In this case, however,
In order to measure the particle size distribution and number of fine particles in liquid,
There are the following problems.

(1) Since droplets adhere to the inner wall of the atomizer 10, the amount of atomization cannot be accurately determined. (2) Since a portion of the atomized liquid is sent to the vaporization chamber to be vaporized, it is difficult to measure the amount of vaporized liquid. (3) Since atomized droplets are transported, their adhesion to the inner wall of the pipe cannot be prevented. (Four)
Since the droplets are vaporized in the vaporization chamber by external indirect heating, the highest temperature is on the inner heated wall surface, so the droplets evaporate most on the wall surface, making it impossible to prevent fine particles from adhering to the wall surface.

As a result of the above, the number and particle size distribution of fine particles in the liquid fed into the aerosol generator do not match the number and particle size distribution of fine particles suspended in the gas exiting the apparatus. Therefore, the particle size distribution and number of particles in a liquid cannot be determined by simply combining an airborne particle measuring device and a known aerosol generator.

The present invention was made to solve the above-mentioned problems, and in the course of its research and study, it was found that the present invention can also be used to measure the amount of salts in a liquid.

[Purpose of the invention]

Therefore, the object of the present invention is to provide a method for measuring impurities in a liquid that includes a liquid atomization and simultaneous vaporization step, which makes it possible to measure the particle size and number of fine particles in a liquid, or to measure the amount of salts in a liquid. and equipment.

[Summary of the invention]

The method of the present invention was developed based on the fact that fine particles with a small particle size can be measured in gas rather than in liquid. That is, in the present invention, the fine particles in the liquid are suspended in the gas by atomizing the liquid and simultaneously bringing the liquid into contact with a high-temperature gas to vaporize the liquid, and the particle size and number of the fine particles are measured in the suspended state. In addition, if the liquid contains salts, the liquid can be vaporized in the same manner as above to suspend the salts in the gas in the form of fine particles, and the particle size and number of the salt particles can be measured in the suspended state. Therefore, it measures the amount of salts in the liquid.

Furthermore, unlike conventionally known standard particle aerosol generators, the device of the present invention (1) minimizes the transportation time of droplets after atomization, and (2) prevents vaporization of droplets through a heat transfer wall. (3) In order to completely vaporize the atomized droplets, the device is inserted between the liquid supply device and the airborne particulate analyzer, and supplies high-temperature gas. The invention is characterized in that it is equipped with a liquid atomization simultaneous vaporizer that receives liquid atomization. In other words, in order to atomize and vaporize the liquid almost simultaneously,
Preheated gas is fed into a liquid atomization and simultaneous vaporizer.

The main points of the present invention will be explained using FIG. The basic flow difference between the present invention and an example using a conventional aerosol generator is that in an example using a conventional standard aerosol generator, a liquid is atomized, a part of it is mixed with a gas, and then it is vaporized. However, in the present invention, the liquid and preheated high-temperature gas are introduced into a simultaneous atomization vaporizer, and the liquid is atomized and brought into contact with the high-temperature gas at the same time. The point is that the entire amount is evaporated.

The vaporization mechanism of droplets is that, in the example using a conventional standard aerosol generator, the droplets are sent into the vaporization chamber and vaporized by external indirect heating. becomes the largest amount, and the fine particles adhere to the wall surface. on the other hand,
In the present invention, since the droplets are suspended in a high-temperature gas in the form of a mist and are simultaneously heated and vaporized directly by the high-temperature gas, the fine particles do not adhere to the wall surface and are all suspended in the air.

Regarding transportation, in an example using a conventional standard aerosol generator, the fine particles in the liquid are transported in the form of droplets, so the droplets adhere to the inner wall of the tube, but in the present invention, the liquid is By keeping the area where it is transported as short as possible and vaporizing it immediately after atomization,
Since the particles are transported in the form of dry particles, they do not adhere to the inner wall of the tube.

[Embodiments of the invention]

An embodiment of the present invention will be described in detail with reference to FIG. 1, taking as an example the measurement of fine particles in water. As shown in the figure, in addition to the atomizing simultaneous vaporizer 31 and the laser scattering light type airborne particle measuring device 40, the gas 120 system includes a filter 51, a heater 61, a gas flow rate detector 52, and a gas flow rate adjustment device. There is a container 53. The liquid supply system includes a liquid supply device 71 that samples a fixed amount of liquid from the main pipe 1 through which the liquid to be measured flows, a liquid flow rate regulator 73, and a liquid flow rate detector 72. Furthermore, there is a controller 80 that controls the amount of gas and liquid.

The carrier gas 120 for heating and evaporating the liquid and transporting the dried particles is filtered by a filter 51 to remove particles from the gas, and then its flow rate is adjusted by a regulator 53 and passed through a flow rate detector 52 to a heater 61.
and enters the atomization/co-vaporizer 31 as a high-temperature gas 121. On the other hand, the sample liquid 100 is in the main pipe 1
A portion of the liquid is sampled by the liquid supply device 71, the flow rate is adjusted by the regulator 73, and then the flow rate detector 72
It enters the atomizer 31 through the Atomization simultaneous vaporizer 31
At the same time as the liquid 100 is atomized into water droplets, it comes into direct contact with the high-temperature gas 121, and the water droplets evaporate in the high-temperature gas, and the entire amount of water droplets is vaporized.
Dry particulates are transported in a state suspended in gas, and part or all of them are detected by the airborne particulate meter 4.
0, and the particle size, particle size distribution, and number of particles are measured. All of the above operations can be performed continuously.

Next, the atomizing and simultaneous vaporizer 31 will be described in more detail. Methods of atomizing liquid include (1) atomizing liquid;
High-pressure nozzle method, in which the liquid is pressurized to 40 to 60 kg/cm ² and sprayed from a nozzle; (2) the rotating disk method, in which the liquid collides with a disk rotating at high speed to atomize the liquid; (3) liquid is sprayed using high-speed gas. There is a two-fluid nozzle method that atomizes the particles, as well as (4) the ultrasonic atomization method, and (5) the high electric field method.

The high electric field method (5) has technical unknowns and safety issues, and the high pressure nozzle method (1) has difficulty generating small particles. Therefore, the remaining three methods can be applied as methods for atomizing the liquid, but considering the point of the present invention, which is to bring the liquid into direct contact with high-temperature gas immediately after atomization to evaporate it, the two fluids in (3) are applicable. The nozzle method is the best. Other methods require a process of atomization using external energy (high-speed rotation, ultrasonic waves) and a process of evaporation by contacting with high-temperature gas, and it is not easy to perform both processes at the same time, but the two-fluid nozzle method By using the high-speed gas used for atomization (atomization) as a heated high-temperature gas, there is an advantage that atomization and evaporation through contact with the high-temperature gas can be performed in the same process.

The effect of using a two-fluid nozzle is that the liquid is atomized and comes into contact with high-temperature gas, which improves heat exchange efficiency and promotes evaporation.As the atomization accompanies evaporation, the diameter of the generated fine water droplets becomes smaller. etc.

FIG. 4 shows an embodiment of a simultaneous atomizing vaporizer 31 suitable for the present invention using a two-fluid nozzle 200. The high temperature gas 121 enters the gas chamber 222 from the gas inlet 221.
enters the nozzle, is narrowed down by the nozzle port 231, and becomes high speed.
The liquid 100 coming out of the liquid nozzle port 212 through the liquid inlet 211 is atomized and atomized, and at the same time, heat is applied to the water droplets by direct contact to evaporate them. Therefore,
In the atomizing simultaneous vaporizer 31', the high-temperature gas gives heat to water droplets and is cooled, and the water droplets are humidified by evaporation. The particles originally present in the liquid 100 are transported in a suspended state in the high-temperature gas, and the suspended particles are sampled together with the gas from the gas sample port 251, which goes to the airborne particle measuring device 40, and the remaining particles are It is discharged from the outlet 241 as exhaust gas.

The next important thing about the simultaneous atomizing vaporizer 31 is that the vaporized gas has high humidity, so when it is cooled, the vaporized water vapor condenses and water droplets are generated. It is necessary to maintain the temperature above the gas temperature after vaporization. For this purpose, it is necessary to insulate the outer surface of the atomizing and simultaneous vaporizer 31 with a heat insulating material 261, or to proactively install a heater 262 in some cases to heat it.

The key point in measurement is to vaporize and evaporate the entire amount of the liquid atomized by the simultaneous atomization vaporizer 31, and it is important to set the flow rate ratio of gas and liquid and the temperature and humidity conditions of the heated gas. . Therefore, various experiments were conducted using the atomizing simultaneous vaporizer 31 shown in FIG. 4, and appropriate flow rate ratios and heating gas conditions were determined.

Figure 5 shows the vaporization rate X (%) defined by the following formula when atmospheric air is used as a carrier gas.
and the weight flow rate ratio F _w /F _g of gas and liquid are shown using the heater input of the heater as a parameter.

Evaporation rate X = vaporization amount (g/h)/atomization amount (g/h)
×100 Increasing the heater input will increase the vaporization rate, but the vaporized gas temperature at the outlet of the vaporizer will increase, so
Practically speaking, the limit is about 150w, so in order to vaporize the entire amount (vaporization rate 100%), Figure 5 shows that it is desirable that the weight flow ratio of gas and liquid, _Fw / _Fg , be 6wt% or less. Recognize.

F _w : Liquid flow rate (Kg/h) F _g : High temperature gas flow rate (Kg/h) The lower limit of the weight flow rate ratio Fw/Fg is based on the increase in carrier gas usage and heater input, and the decrease in the number of fine particles in the liquid. Considering the upcoming increase in measurement time, 0.5 wt% or more is practically appropriate.

Next, various experiments were conducted to optimize the conditions for the high-temperature gas sent to the atomizing and simultaneous vaporizer 31. Figure 6 shows the relationship between the flow rate ratio F _w /F _g and the temperature T of the high-temperature gas necessary to vaporize the entire amount of liquid, and Figure 6 shows the relationship between the flow rate ratio F _w /F _g and the relative humidity R of the high-temperature gas. It is shown in Figure 7. As a result, the high temperature gas temperature T required to vaporize the entire amount is approximately proportional to the flow rate ratio, but the minimum flow rate ratio is
Since it is 0.5wt%, it was found that the temperature must be at least 40°C or higher, and that the relative humidity R also needs to be at most 20% or less from the relationship of the minimum flow rate ratio.

To set the above measurement conditions, specifically,
Regarding the flow rate ratio F _w /F _g, the flow rates of liquid and gas are detected by detectors 72 and 52 as shown in the embodiment of FIG. did. The high temperature gas conditions are generally set by detecting the temperature and humidity of the high temperature gas and controlling the heater input, but it is difficult to accurately measure the humidity of the high temperature gas. However, by detecting the gas flow rate and liquid flow rate, it is possible to easily calculate the heater input required to obtain high temperature gas at the desired temperature and humidity. Detector 7 detects the flow rate of gas and liquid
2 and 52, the necessary heater input was calculated by the controller 80 based on the value, and the heater input of the heater 61 was adjusted.

Note that the airborne particle measuring device is preferably a measuring device that uses laser scattered light. An example of such a measuring device is shown in Yasuo Mukaiita, "On the Monitoring and Measurement of Submicron Aerosol Particles", magazine "Air Conditioning and Refrigeration", January 1984 issue, pages 79-81.

The above explanation uses fine particles in liquid as an example, but soluble impurities such as salts can be measured in the same way in the form of fine particles, and if the liquid contains both fine particles and soluble impurities, these impurities can be measured all at once.

〔Effect of the invention〕

According to the present invention, since the entire amount of the liquid can be vaporized without adhering to the inner wall of the pipe, it is possible to accurately measure particles or salts in the liquid. Furthermore, since the liquid is vaporized and measured, the particle size and number of smaller particles or the amount of salts can be continuously measured compared to the case where the liquid is measured as it is.

[Brief explanation of drawings]

FIG. 1 is a flow sheet of an example of the present invention, FIG. 2 is a flow sheet of an example using a conventional aerosol generator, and FIG. 3 is a comparison chart of an example using a conventional aerosol generator and the present invention. Figure 4 is a cross-sectional view of a simultaneous atomizing vaporizer using two liquid nozzles, Figure 5 is a diagram showing the relationship between vaporization rate, weight flow rate ratio of liquid and gas, and heater input, and Figure 6 is a diagram showing the relationship between high temperature gas temperature and heater input. A diagram showing the relationship between the weight flow rate ratio and FIG. 7 is a diagram showing the relationship between the high temperature gas relative humidity and the weight flow rate ratio. DESCRIPTION OF SYMBOLS 1... Main piping of the liquid to be measured, 31... Atomization simultaneous vaporizer, 40... Airborne particulate measuring device, 51... Filter, 61... Heater, 80... Controller, 200
...Two-fluid nozzle.

Claims (1)

[Claims] 1. A liquid is atomized and at the same time brought into contact with a high-temperature gas to vaporize it so that impurities in the liquid are suspended in the gas as fine particles, and the fine particles are suspended in the gas. A method for measuring impurities in a liquid, characterized by measuring the particle size or particle size and number of particles. 2. When the liquid is water, the method for measuring impurities in a liquid according to claim 1, wherein the temperature of the high-temperature gas used is 40°C or higher, or the relative humidity is 20% or lower. 3 Weight flow rate ratio of liquid and high temperature gas (liquid/high temperature gas)
is from 0.5wt% to 6wt%
The method for measuring impurities in a liquid according to item 1 or 2. 4. Claims 1, 2, or 3 in which a liquid is continuously sampled, and the liquid is continuously atomized and simultaneously brought into direct contact with a high-temperature gas to vaporize it.
Method for measuring impurities in liquid as described in section. 5 comprising a liquid supply device, a high-temperature gas supply device, an airborne particle measuring device, and a liquid atomization simultaneous vaporizer inserted between the liquid supply device and the high-temperature gas supply device, The co-vaporizer receives a liquid and a high-temperature gas from the liquid supply device and high-temperature gas supply device, respectively, atomizes the liquid, and at the same time vaporizes the liquid by bringing it into contact with the high-temperature gas. A device for measuring impurities in a liquid, characterized in that impurities in the liquid are suspended in the gas as fine particles, and the gas with the fine particles suspended is sent to the airborne particle measuring device. 6. The device for measuring impurities in a liquid according to claim 5, wherein the liquid atomization and simultaneous vaporizer uses two-fluid nozzles connected to the liquid supply device and the high-temperature gas supply device, respectively. 7. The device for measuring impurities in a liquid according to claim 5 or 6, wherein the airborne particle measuring device is a measuring device using laser scattered light. 8. A flow rate detector and a flow rate regulator are provided in the supply liquid flow path from the liquid supply device and the supply gas flow path from the high-temperature gas supply device, as set forth in claim 5, 6, or 7. Device for measuring impurities in liquid. 9. Impurities in the liquid according to any one of claims 5 to 8, wherein the liquid atomization simultaneous vaporizer is equipped with a container that insulates or heats the gas in which the fine particles are suspended. measuring device.