JPH07111440B2 - Measuring method of gas flow - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas flow measuring method.

The term "measurement of gas flow" as used herein means not only measurement of gas flow velocity but also measurement by visualization of gas flow distribution.

[0003]

2. Description of the Related Art Seeding particles used for measuring a gas flow using an optical measuring device such as a gas velocity measuring device using a laser measuring device include SiO ₂ and TiO ₂ . ₂ , porous particles such as SiC (average particle diameter of 0.5 to 150 μm) were used. Examples of the method of measuring the gas flow velocity using the laser measuring device include a method using a laser Doppler velocity meter, a phase Doppler velocity meter, or the like. In this case, particles having an average particle diameter of about 0.5 to 10 μm were used.

As another example of the gas flow measuring method, the gas flow is measured by taking a photograph of the distribution of seeding particles using an instantaneous and powerful light source such as a flash lamp or a pulse laser. There is a method of measuring. In this case, the average particle size is 5 to 150 μm.
Some particles were used.

Examples of the porous particles include those produced by the coprecipitation method and those utilizing natural products.

Electron micrographs of typical seeding particles conventionally used are shown in FIGS.
(FIGS. 3 and 4 are white carbon, FIGS. 5 and 6 are TiO ₂ ,
7 and 8 are talc, FIGS. 9 and 10 are TiO ₂ + talc, FIGS. 11 and 12 are samples taken from Kanto Loam, and FIGS.
4 is a photograph of white fused alumina. However, such seeding particles, as clearly shown in the photograph, have the following defects 1 to 5 and increase the gas flow measurement error.

1) Since the seeding particles have an indeterminate shape, the scattering cross section of light to be detected by the photodetector differs depending on the direction of the particles at the time of light detection. 2) The particle size distribution of the particles is wide and the light scattering cross-section is different for each particle, and relatively large particles scatter light simultaneously in two or more light interference fringes.

3) Since the apparent specific gravity of the particles is heavy, the particles do not sufficiently follow the gas flow.

4) Since the particle size distribution is wide and the apparent specific gravity is also distributed, the followability of the particles to the gas flow varies, and the gas flow cannot be quantitatively evaluated.

5) There are irregularities on the surface of the particles, the particles are caught by each other and agglomerate to increase the effective particle size.

As a conventional method of mixing seeding particles into a gas fluid, for example, a method of blowing seeding particles extruded by a screw feeder with an air stream or after suspending the seeding particles in a solvent, There is a method of spraying with a sonic humidifier.

However, in any of the above methods, the amount of seeding particles supplied was not constant, resulting in a measurement error.

[0013]

[Means for Solving the Problems] Therefore, in order to solve the above problems, the following means were taken.

That is, the measuring method according to the first invention is
This is a method of using ceramic porous spherical particles having a diameter of 0.5 to 150 μm as seeding particles in a gas flow measuring method using an optical measuring device.

Among the above measuring methods, in the gas velocity measuring method using a laser measuring device such as a laser Doppler velocity meter, it is preferable to use spherical particles having a diameter of 0.5 to 10 μm. Among them, the diameter is 1.5-2.
It is further preferred to use spherical particles of 5 μm.

In the method of measuring the gas flow using photography, it is preferable to use spherical particles having a diameter of 5 to 150 mμm. Among them, diameter 30-100
It is further preferred to use spherical particles of μm.

It is preferable that the seeding particles are hollow spherical particles.

It is preferable that the seeding particles are made of SiO ₂ .

It is preferable that 70% or more of the seeding particles have a particle diameter within a range of an average particle diameter of ± 50%.

The seeding particles are preferably produced by the reverse micelle method.

In this case, an aqueous solution containing the seeding particle raw material is extruded from a porous glass membrane having a substantially uniform pore diameter or a polymer membrane having pores having a substantially uniform pore diameter into an organic solvent to prepare reverse micelles having uniform diameters. More preferably, the seeding particles are produced by forming.
As an example, in the case of producing SiO ₂ particles, sodium silicate or the like is used as the seeding particle raw material.

It is preferable to supply the seeding particles to the laser measuring device by a measuring wheel type powder feeder.

[0023]

If the seeding particles used for measuring the gas flow using the optical measuring device are spherical, the scattering cross section of the light to be detected by the photodetector is It is constant regardless of. Further, since there is no unevenness that causes a catch on the surface, two or more seeding particles do not flow in the fluid while aggregating. These can improve the measurement accuracy of the gas flow.

If the seeding particles are hollow spherical particles, the apparent specific gravity becomes small and the gas flow is easily followed. Thereby, the measurement accuracy of the gas flow can be further improved. The hollow spherical seeding particles have higher measurement accuracy than the spherical seeding particles, and the difference between the two is remarkable especially in a high-speed fluid.

The thickness of the shell in the hollow spherical particles is not particularly limited, but is 1/3 to 1/10 of the diameter of the particles.
Is preferred. If it is less than 1/10, it is easily broken in the fluid, and if it exceeds 1/3, the effect of being hollow cannot be obtained so much.

The material of the seeding particles is not particularly limited as long as it is white and chemically stable, and alkaline earth metal carbonates such as calcium carbonate and barium carbonate; calcium silicate, magnesium silicate, copper oxide and the like. Alkaline earth metal silicates; examples thereof include metal oxides such as SiO ₂ , iron oxide, and alumina. Of these, SiO ₂ is preferable because it is inexpensive and has excellent heat resistance. If it has excellent heat resistance, it can be sufficiently used even in a high temperature fluid without being destroyed.

It is desirable that the particle size distribution of the seeding particles is narrow, but if the particle size of 70% or more of the seeding particles is within the range of the average particle size ± 50%, a substantially uniform light scattering cross-sectional area is obtained. Can be obtained. Further, the behavior of the seeding particles in the air flow, in other words, the easiness of following the gas flow is substantially constant. Further, even if the sample data rate increases, the average effective data rate does not decrease. That is, for example, in a gas velocity measurement method using a laser Doppler velocity meter, conventionally, even if the seeding particle supply amount is increased to increase the number of data per unit time (sample data rate), the average effective data is increased. The rate drops and the sample data rate does not increase much. However, using the method of the present invention, the sample effective data rate can be easily increased because the average effective data rate does not decrease to a particle concentration higher than the conventional one.

When the reverse micelle method is adopted when producing the seeding particles, it is possible to easily produce the spherical or hollow spherical porous seeding particles at low cost.

Further, when a reverse micelle is produced, when an aqueous solution of a reactant is extruded into an organic solvent from a porous glass membrane having a substantially uniform pore size or a polymer membrane having pores having a substantially uniform pore size, Further, it is possible to obtain particles having a uniform particle diameter, in other words, a narrow particle diameter distribution, which is more desirable as a seeding particle.

If the seeding particles are supplied to the laser measuring device by a measuring wheel type powder feeder, the supply amount can be quantitatively supplied, and the improvement of the measurement accuracy becomes more remarkable. Since the measurement accuracy is low in the conventional method, it is necessary to set the condition of the measurement unit to maintain the measurement accuracy for each measurement. However, since this method is not necessary in this method, many measurements can be performed within a fixed time.

In the method of measuring the gas flow using photography, the distribution of seeding particles at the time of supply can be made constant, so that the particle distribution after that, that is, the gas distribution can be measured accurately. .

[0032]

According to the present invention, the accuracy of gas flow measurement is significantly improved.

[0033]

EXAMPLES In order to further clarify the present invention, examples will be given below.

Example 1 SiO _{2 having an} average particle size of 1.5 μm and a standard deviation of 0.3 μm
Using a porous hollow spherical seeding particle (the thickness of the shell of which is ⅕ of the diameter of the particle), the feeding test was performed using a measuring wheel type powder feeder and a screw feeder.

Both the measuring wheel type powder feeder and the screw feeder could be supplied with high accuracy, but if the measuring wheel type powder feeder is used, seeding particles of 0.3 ±
It was possible to supply to the laser measuring device with an accuracy of 0.01 g / min, and it was possible to obtain a supply accuracy about 5 times higher than that of the screw feeder. In the measurement of the gas flow velocity using the laser measuring device, if the accuracy of supplying the particles to the measuring device is high, it is easily predicted that the measuring accuracy obtained by the gas flow velocity measuring device is also high.

Comparative Example 1 Cohesive average particle diameter of 1.5 μm which has been conventionally used
Using a seeding particle made of SiO _{2 of} No. 3, a feeding test was performed using a measuring wheel type powder feeder and a screw feeder. With the measuring wheel system, the seeding particles were aggregated and the seeding particles could not be supplied.

The feeding accuracy of the seeding particles by the screw feeder is 0.3 ± 0.14 g / min. Compared with Example 1, it is better to use spherical seeding particles for the laser measuring device. It was found that the supply accuracy was high. In the measurement of the gas flow velocity using the laser measuring device, if the accuracy of supplying the particles to the measuring device is high, it is easily predicted that the measuring accuracy obtained by the gas flow velocity measuring device is also high.

Reference Example 1 and Comparative Example 2 Non-aggregating average particle diameter of 5 μm, which has been conventionally used.
Using the seeding particles of TiO _{2 of} No. 3, a feeding test was performed using a measuring wheel type powder feeder (Reference Example 1) and a screw feeder (Comparative Example 2). Supply accuracy is 0.3 ± 0.02g /
min, 0.3 ± 0.08 g / min, and it was found that the measuring accuracy of the measuring wheel type powder feeder was excellent.

Example 3 70% of the particles had an average particle diameter of 1.5 μm ± 0.4.
Using hollow spherical seeding particles (the thickness of the shell is 1/5 of the diameter of the particles) made of SiO ₂ within the range of μm, the velocity of the air flow in the cylinder measured by the laser measuring device is It was measured (average flow velocity about 20 m / min).

1. Measuring device Fiber type laser Doppler velocimeter (specification) Laser: He-Ne laser Laser power 8 mW x 2 Lens diameter: 55 mm 2. Measurement conditions Measurement center frequency: 20 MHz Bandwidth: ± 16 MHz Effective sample number: 5,000 Signal gain: 24 dB Photomal voltage: 760 V The results are shown in Table 1.

[0041]

[Table 1]

As is clear from Table 1, even if the sample data rate is increased, the average effective data rate, which is one of the representative indexes showing the measurement accuracy, does not decrease so much, and the measurement accuracy is higher than that of Comparative Example 3. You can see that is getting better.

Example 4 90% of the particles had a particle size in the range of 1 to 5 μm, and S
hollow sphere of seeding particles consisting iO ₂ (shell thickness 1/5 the diameter of the particles) used The experiment was conducted in the same manner as in Example 3. The results are shown in Table 2.

[0044]

[Table 2]

As is clear from Table 2, the average effective data rate is inferior because the seeding particles have a wider particle size distribution than in Example 3, but a stable effective data rate was obtained even at a high sample data rate. .

Comparative Example 3 Wet method white carbon (average primary particle diameter 0.2 μm) shown in FIGS.
m, average aggregate particle diameter (effective particle diameter) 6 μm, manufactured by Nippon Silica Industry Co., Ltd., NIPSIL SS-50F), and the same experiment as in Reference Example 1 was performed. The results are shown in Table 3.
Described in.

[0047]

[Table 3]

As is apparent from Table 3, the average effective data rate was lower than those of Examples 3 and 4, and the extremely high sample data rate resulted in an extremely low result.

It can be easily predicted that the same results as above can be obtained by using the conventional seeding particles as shown in FIGS. 3 to 14 instead of using the white carbon.

Example 5 Measurement accuracy when spherical seeding particles were used,
In order to examine the measurement accuracy when using hollow spherical seeding particles by changing the velocity of the gas fluid in the laser measuring device (at low speed and at high speed), 70% of the particles had an average particle diameter of 2 The same experiment as in Example 3 was conducted using spherical particles in the range of 0.5 ± 0.7 μm (see FIGS. 1 and 2). The results are shown in Table 4.

[0051]

[Table 4]

As is clear from Table 4, in both cases, high measurement accuracy was obtained at low speed and high speed.
Particularly at high speed, the hollow spherical seeding particles had higher measurement accuracy than the spherical seeding particles.

Example 6 and Comparative Example 4 Average particle diameter 5 μm and particle specific gravity 6 which have been conventionally used
g / cm ³ seeding particles for fluid visualization made of TiO ₂ (corresponding to Comparative Example 4), having an average particle diameter of 30 μm and a particle specific gravity of about 1 g / cm ³ having almost the same average fluid following behavior as the seeding particles. Using SiO ₂ porous spherical particles (corresponding to Example 6, 72% is in the range of particle diameter ± 50%), a fluid visualization experiment was conducted by a photography method. As a result, the average amount of reflected light per particle in the porous spherical particles was about 20 times that of the conventional particles.

In addition, in the width of the flow of particles in the laminar flow region, the porous spherical particles are about 0.
It was 8 to 0.5 times.

When the average fluid following behavior is almost the same, if the average reflected light amount, that is, the signal amount is larger, and the spread width of the particle flow in the laminar flow region is narrower,
As a matter of course, it is easily inferred that the measurement accuracy of the gas flow is high.

Further, even if the conventional seeding particles as shown in FIGS. 3 to 14 were used instead of the seeding particles used in Comparative Example 4, the same result as above was easily obtained. Can be predicted.

Example 7 and Comparative Example 5 Further, instead of using the SiO ₂ porous spherical particles having an average particle diameter of 30 μm, Si having an average particle diameter of 100 μm was used.
For visualizing a TiO ₂ fluid using O ₂ porous spherical particles (corresponding to Example 7, 72% is in the range of particle diameter ± 50%) and having substantially the same fluid following behavior. The same visualization experiment as described above was performed using seeding particles (corresponding to Comparative Example 5).

The SiO ₂ porous spherical particles having an average particle diameter of 100 μm were superior in both the average reflected light amount and the spread width of the particle flow in the laminar flow region.

[Brief description of drawings]

FIG. 1 is an electron micrograph of particles used in Example 5 (magnification: 2,000 times).

FIG. 2 is an electron micrograph of particles used in Example 5 (magnification: 10,000 times).

FIG. 3 is an electron micrograph of particles used in Comparative Example 3 (magnification: 10,000 times).

FIG. 4 is an electron micrograph of particles used in Comparative Example 3 (magnification: 50,000).

FIG. 5 is an electron micrograph of particles (TiO ₂ ) used conventionally (magnification: 10,000 times).

FIG. 6 is an electron micrograph of particles (TiO ₂ ) used conventionally (magnification: 50,000).

FIG. 7 is an electron micrograph of conventionally used particles (talc) (magnification: 1,000 times).

FIG. 8 is an electron micrograph of particles (talc) used conventionally (magnification: 10,000 times).

FIG. 9 is an electron micrograph of conventionally used particles (TiO ₂ + talc) (magnification: 10,000 times).

FIG. 10 is an electron micrograph of conventionally used particles (TiO ₂ + talc) (magnification: 50,000).
Times).

FIG. 11 is an electron micrograph of conventionally used particles (collected from Kanto Loam) (magnification: 10,
000 times).

FIG. 12 is an electron micrograph of conventionally used particles (collected from Kanto Loam) (magnification 50,
000 times).

FIG. 13 is an electron micrograph of conventionally used particles (white fused alumina) (magnification: 2,000 times).

FIG. 14 is an electron micrograph of conventionally used particles (white fused alumina) (magnification: 10,000).
Times).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Ikeda 111-1 -205 Miyasaka, Ninata, Ninya, Nada Ward, Kobe City, Hyogo Prefecture

Claims (9)

[Claims] 1. A method of measuring a gas flow by an optical measuring device using porous ceramic particles as seeding particles, wherein the seeding particles are spherical particles having a diameter of 0.5 to 150 μm. Measuring method of gas flow. 2. A method for measuring a gas flow velocity using a laser measuring device such as a laser Doppler velocity meter, wherein the seeding particles are spherical particles having a diameter of 0.5 to 10 μm. 1. The method for measuring the gas flow according to 1. 3. A gas flow measuring method for measuring a gas flow by taking a photograph of a distribution of seeding particles using an instantaneous and powerful light source such as a flash lamp or a pulse laser. The gas flow measuring method according to claim 1, wherein the ding particles are spherical particles having a diameter of 5 to 150 μm. 4. The gas flow measuring method according to claim 1, wherein the seeding particles are hollow spherical particles. 5. The gas flow measuring method according to claim 1, wherein the seeding particles are made of SiO ₂ . 6. The gas flow according to claim 1, wherein 70% or more of the seeding particles have an average particle size of ± 50%. Measuring method. 7. The seeding particle is produced by a reverse micelle method, according to claim 1.
The method for measuring the flow of gas according to item. 8. A reverse micelle is formed by extruding an aqueous solution containing a seeding particle raw material from a porous glass membrane having a substantially uniform pore diameter or a polymer membrane having pores having a substantially uniform pore diameter into an organic solvent to form reverse micelles. The gas flow measuring method according to claim 7, wherein the seeding particles are manufactured. 9. The measuring wheel type powder feeder supplies the seeding particles to an optical measuring device such as a laser measuring device.
The method for measuring the gas flow according to any one of 1.