JP3188262B1 - Salt spray test equipment - Google Patents

Abstract

[PROBLEMS] To test so that the variation in temperature distribution in a test tank and the variation in salt concentration and specific gravity of a sampled liquid are within a certain range, and the temperature in the test tank can be quickly raised to the test temperature. Heating the tank. SOLUTION: A steam generator and a means for spraying generated steam to a bottom portion in a test tank are attached to the test tank, and the steam is supplied into the test tank at a constant rate, so that the test can be performed without lowering the humidity. The salt spray test is performed while maintaining the temperature in the tank constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a salt spray test apparatus used for a corrosion test.

[0002]

2. Description of the Related Art In a salt spray test, a test is performed by spraying a corrosive liquid to corrode a test object. In detail, the etching is performed by spraying the corrosive liquid together with saturated air from a spray nozzle as a mist from a spray tower into a test tank, and allowing the mist to naturally drop from above and contact a test piece arranged in the tank. Then, corrosion of the test piece is promoted by the mist. The salt spray test apparatus used in the test has a spray nozzle provided in a test tank, and is configured to send saturated air to the spray nozzle to suck up and spray the salt solution.

In the salt spray test, JIS Z 2
As specified in 371: 2000, the temperature in the test chamber must remain at 35 ± 2 ° C. during the test.
In the conventional salt spray test apparatus, the test tank was heated by a heater method. There are four types of heater systems.

[0004] One is a type in which a heater is directly placed in a test tank. In addition, the second is Japanese Patent Publication No. 40-254.
As described in No. 00, a heater is placed in a corrosion solution before spraying to heat the corrosion solution. On the other hand, the third is the Japanese Utility Model Publication No. 56-122942
As described in JP-A-4-23919, two test tanks were used.
This type is a heavy tank and a heater is inserted into the gap between the tanks. The fourth type is a type in which a test tank is doubled, water is supplied between the tanks, and water is heated by a heater, as described in Japanese Utility Model Publication No. 58-8361 and Japanese Utility Model Application Publication No. 64-36063. It is.

The salt damage test apparatus described in Japanese Utility Model Laid-Open No. 52-114087 is connected to a humidifying spray connected to a steam generator at the upper part of a test tank, a cooler and a heater connected to a refrigerator. The temperature and humidity are adjusted by a heater. Since the above method does not result in natural convection, it cannot be applied to the salt spray test.

[0006]

In the type in which the heater is directly inserted into the test tank, there is a problem that the salt concentration of the spray mist rises in the test tank due to evaporation of water near the heater. In the type in which the corrosion liquid is heated by putting a heater into the corrosion solution before spraying, the salt concentration of the spray solution increases before spraying due to evaporation of water near the heater and condensation of water due to heat radiation from the test tank wall. There was a problem. In the type where the test tank is a double tank and a heater is inserted into the gap between the tanks, and in the case where the test tank is a double tank and water is inserted between the tanks and the water is heated by the heater, the temperature of the test tank is reduced to the test temperature. There are problems that it takes time to raise the temperature and that the cost of producing a test tank is high.

[0007] The salt concentration of the spray mist is required to be within a certain range depending on the specific gravity of the collected liquid. JIS
As specified in Z 2371: 2000, the specific gravity of the spray liquid collected at the time of spraying is 25 ° C.
It must be 1.029 or more and 1.036 or less. When the specific gravity is within the above range, the salt concentration is 50 ±
It is said to be 5 g / L.

However, in the above-mentioned conventional type in which a heater is directly placed in a test tank, a spray liquid having a specific gravity of 1.0323 at 25 ° C. before spraying, that is, a salt concentration of 50 g / L, is collected after spraying. The liquid has a problem that the salt concentration is 6.6 wt%, that is, 66 g / L, in other words, the specific gravity is 1.048.

[0009] If the salt concentration and specific gravity of the collected spray liquid are out of the specified range, the reliability of the test results may be affected.

On the other hand, the temperature rise rate is slow in the conventional double tank type described above. For example, in a type in which the test tank is a double tank, water is supplied between the tanks, and the water is heated by a heater, the temperature is 20 ° C. 48 minutes to increase from
There was a problem that it took one and a half hours to raise the temperature from 5 ° C. to 50 ° C., and it took time to start the test.

That is, in the conventional salt spray test apparatus, the test tank is heated uniformly evenly in a short time and the test temperature is maintained without increasing the test tank production cost, and the salt concentration of the sampled liquid is within the specified range. There was a problem that it was not possible to do so, and the reliability of the test could be reduced.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to reduce the cost of producing a test tank while keeping the salt concentration within a specified range and the uniformity of temperature distribution in the test tank. It is an object of the present invention to provide a salt spray test apparatus capable of rapidly heating a test tank.

[0013]

The salt spray test apparatus of the present invention comprises: (a) a steam generator for generating steam, and (b) a steam inlet connected to the steam generator and penetrating through the bottom of the test tank. (C) maintaining the temperature in the test tank within a certain range and maintaining the salt concentration of the sampled liquid within a certain range,
It is characterized by having means capable of ejecting water vapor from the steam inlet into the test tank toward the bottom and / or side surface of the test tank.

[0014] Means for allowing steam to be ejected from the steam inlet toward the bottom and / or side surface of the test tank from the steam inlet into the test tank is provided with the steam inlet as a starting point, and It is preferable that the at least one pipe is provided below the inside of the test tank and has a plurality of holes facing downward and / or in the side direction of the test tank so as to blow water vapor toward the bottom surface.

The pipe is preferably cylindrical or plate-shaped.

[0016] The steam generated by the steam generator is sent to each of the pipes through the steam inlet connecting the steam generator and the inside of the test tank. Alternatively, saturated steam is supplied into the test tank from a plurality of holes in the side direction of the test tank toward the bottom of the test tank.

The temperature of the steam in the steam generator is 100 ° C.
However, as the steam flows into the steam inlet, the pipe, and the hole, heat is released through the pipe, and the temperature of the steam decreases.

Further, a means capable of jetting steam from the steam inlet into the test tank toward the bottom and / or the side of the test tank is provided in contact with the steam jetted upward from the steam inlet. And, so that the jet direction of the steam can be directed to the lower and side directions of the test tank,
A plate provided above the steam inlet may be used.

The steam generated by the steam generator is jetted from the steam inlet connecting the steam generator and the inside of the test tank, contacts the plate and dissipates heat, and changes the jetting direction from upward to downward and to the side. Turning to the direction, it is supplied into the test tank as saturated vapor toward the bottom of the test tank.

In place of the above-mentioned plate, a box without a bottom surface may be provided so that the steam jetted upward from the steam inlet contacts the box and the jet direction of the steam is directed downward and to the side of the test tank. You may be able to.

Further, the temperature distribution in the test tank varies within 0.5 ° C., and the specific gravity of the sampled liquid is 25 ° C.
Is preferably 1.029 or more and 1.036 or less.

It is preferable that the amount of water vapor supplied from the steam generator into the test tank is equivalent to the amount of water vapor lost due to condensation in the test tank.

Further, it is preferable to have a filter for purifying water supplied to the steam generator.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the drawings by the following embodiments.

FIG. 1 is a schematic front view, partially cut away, showing an example of a configuration of a salt spray test apparatus to which the present invention is applied. FIG.
The apparatus of Example 1, which is one configuration example shown in FIG.
0) is heated by steam supplied from a steam generator (1) through a steam pipe (3), kept at a test temperature, and sprayed with a salt solution supplied from a solution supply tank (13) using a float. A nozzle (8) is sprayed as a mist from a spray tower (9) together with air saturated with an air saturator (7) into a test tank (10), and a test piece (11) placed in the tank is sprayed. This is a salt spray test device (12) that is subjected to a corrosion test by allowing the mist to fall naturally from above and contact the mist, and the sprayed mist is collected by a collector (15). The steam supplied into the test tank (10)
It is configured not to directly contact the test piece (11).

FIG. 2 is a perspective view of a main part in the test tank according to the first embodiment of the present invention shown in FIG. FIG. 3 shows Embodiment 1 of the present invention.
FIG. 4 is a perspective view of a main part of a steam supply part of FIG. In the first embodiment, the steam is supplied from the steam generator (1) to the steam inlet (2).
And a steam pipe (3) provided below the test tank (10), and a plurality of downwardly directed steam jets provided on the pipe (3) so as to blow steam toward the bottom of the test tank (10). It flows to the outlet (4) and is fed into the test tank (10). The steam generator (1) is provided with a water filter (6) for purifying water supplied to the steam generator. An exhaust port (14) is provided directly below the spray tower.

When the steam flows through the pipe (3), the heat of the steam is transmitted to the pipe, and is radiated into the test tank (10) through the pipe.

In the first embodiment shown in FIGS. 1 and 2, the steam pipe (3) has a cylindrical shape. However, the steam pipe (3) may have any other shape as long as it functions as a heat radiating medium. .

The spray mist is supplied to the test tank at a rate of 300 mL / hour during the test. Therefore, during the test, the inside of the test tank is saturated with the spray mist and the steam supplied from the steam generator, and the relative humidity is 98% RH or more. On the other hand, the inside of the test tank is maintained at the test temperature of 35 ± 2 ° C. Therefore, the temperature inside the test chamber is generally higher than the outside temperature,
In addition, since it is in a saturated state, dew forms on the inner wall of the test tank. Therefore, when steam is not supplied, the salt concentration of the spray mist increases, and the specific gravity of the sampled liquid becomes 1.036 or more at 25 ° C., which exceeds the specified range. However, by supplying the same amount of water vapor as the amount of dew condensation on the inner wall of the test tank, an increase in salt concentration can be prevented.

In terms of temperature, the heat in the test tank is radiated to the outside air through the walls of the test tank due to the temperature difference from the outside air temperature. Then, the water is heated by a steam generator to form steam, and the heated steam is passed through the pipe to give heat through the wall of the pipe, and heat is also given by jetting a part of the steam into the test tank.

The present invention has a structure in which the temperature and the humidity are not controlled separately, but are associated with each other, in other words, interfere with each other, and can be controlled together. Applicants also refer to the temperature and humidity controlled together as interference temperature and interference humidity.

As the test tank, a single tank made of a heat-insulating resin is used.

In the first embodiment, a 1 kW heat is applied to the steam generator.
Use one bottle. The temperature in the test chamber rises to the test temperature
After ascending, 20 seconds is one cool of heater on / off
Turn on for 5 seconds and off for 15 seconds. then
In addition, the amount of heat per hour given to water from the heater is
From Equation 1, it is 900 kJ / hour. In Equation 1, Q ₁
(KJ / hour) is equivalent to 1 hour given from heater to water.
A (kW) is the heater capacity, a (second) and b
(Sec) is the time to turn on the heater and the time to turn it off
Time.

[0034]

(Equation 1)

The heater is controlled by a PID control method based on the temperature in the test chamber obtained by a sensor inserted into the test chamber.

The water filter (6) removes impurities contained in the water supplied to the steam generator, so that an unnecessary amount of heat is not required.

In Embodiment 1, water at 23 ° C. is supplied to the steam generator at a rate of 0.3 kg / hour. Since the specific heat of water at 100 ° C. is 4.21 kJ / kg · K, the heat quantity per hour necessary for warming the supplied water to 100 ° C. is 97 kJ / hour based on Equation 2. In Equation 2, Q ₂ (kJ / hour) is the amount of heat per hour required to warm the supplied water to 100 ° C., y (kg / hour) is the amount of water per hour supplied, and c (kJ / kg)・ K) is 10
Specific heat of water at 0 ° C.

[0038]

(Equation 2)

The steam generator has a surface area of 0.256 m²so
Yes, wall thickness is 15mm and thermal conductivity is 0.029W /
(MK) stainless steel, so the outside air temperature is 2
At 3 ° C, of the amount of heat
The amount of lost heat radiated around the air generator is as shown in Equations 3 and 4.
To 98 kJ / hour. In Equation 3, Q₃(KJ
/ Hour) is the amount of heat released around the steam generator per hour.
Calorific value, κ₁[W / (m ²・ K)] from inside the steam generator
Heat transfer rate to the outside air through the wall, F₁(M ²) Is a wall
Surface area, ΔT₁(K) is the temperature inside the steam generator and the outside air temperature
And the temperature difference. In Equation 4, α₁[W / (m²・
K)] is the heat transfer coefficient of air in the steam generator, α₂[W /
(M²· K)] is the heat transfer coefficient of the outside air, L₁(M) is
Wall thickness, λ₁[W / (m · K)] is the thermal conductivity of the wall
You. Note that empirically, α₁Is 582W / (m²・ K),
α₂Is 4.93W / (m²・ K)
I have.

[0040]

(Equation 3)

[0041]

(Equation 4)

The steam of 0.3 kg / hour generated by the steam generator flows from the steam generator to the steam inlet and the pipe. A part thereof is supplied into the test tank as water vapor, and serves to heat the test tank, keep the humidity constant, and keep the salt concentration constant. The remaining water vapor is condensed in the pipe and gives only heat to the test tank, and serves to keep the temperature constant.

On the other hand, in Example 1, a test tank made of vinyl chloride resin having a total surface area of 3.82 m ² , a thickness of 5 mm, and a thermal conductivity of 0.163 W / (m · K) When the test is carried out using the formula (1), the amount of heat radiated from the wall of the test tank during the test at 35 ° C. when the outside air temperature is 23 ° C. is 702 kJ / hour from Formulas 5 and 6.
In Equation 5, Q ₄ (kJ / hour) is the amount of heat per hour radiated to the outside air through the test chamber wall during the test, κ
₂ [W / (m ² · K)] is the heat transfer rate from the inside of the test tank to the outside air through the wall, F ₂ (m ² ) is the surface area of the wall, Δ
T ₂ (K) is the temperature difference between the temperature inside the test tank and the outside air temperature. In Equation 6, α ₁ [W / (m ² · K)] is the heat transfer coefficient of the air in the test tank, L ₂ (m) is the wall thickness, and λ ₂ [W
/ (M · K)] is the thermal conductivity of the wall. It has been empirically found that α ₁ is 582 W / (m ² · K).

[0044]

(Equation 5)

[0045]

(Equation 6)

Furthermore, the amount of heat radiated because the saturated air at 35 ° C. which flows into the test tank at 0.3 kg / hour is exhausted from the exhaust port to the outside air at 23 ° C. is 3.6 kJ / hour. .

Therefore, the heat radiation from the test tank wall and the heat radiation from the exhaust are obtained by subtracting the amount of heat lost from the wall of the steam generator and the amount of heat consumed by heating the water from the amount of heat provided by the heater, that is, It is almost the same as the amount of heat given to the test tank from the generator.

Therefore, the temperature in the test tank is kept constant by the steam generator.

In Example 1, the inner diameter of the steam pipe was
13mm, outer diameter 18mm, total length 1.51m, heat transfer
When using pipes with a conductivity of 0.163 W / (m · K)
If the heat is radiated into the test chamber through the pipe wall for 1 hour,
The amount of heat (kJ / hour) of the pipe was
Since the temperature in the test tank is 35 ° C,
J / hour. In equation 7, Q₅(KJ / hour) is
The amount of heat per hour radiated into the test chamber through the wall,
κ₃[W / (m²・ K)] through the pipe wall from inside the pipe
Heat transfer rate moving into the test tank, L₃(M) is the piping wall
Overall length, ΔT₃(K) is the temperature difference between the pipe and the test tank.
You. In equation 8, r₁(M) is the inner diameter of the pipe, r ₂(M) is distribution
Outer diameter of tube, α₃[W / (m²・ K)] is the air
Heat transfer coefficient, λ₃[W / (m · K)] is the thermal conductivity of the pipe wall
It is. Note that empirically, α₃Is 23.3 W / (m²・
K).

[0050]

(Equation 7)

[0051]

(Equation 8)

On the other hand, the amount of water was supplied at a rate of 0.3 kg / hour because the salt concentration of the sampled liquid was 6.6 wt% in a type in which the heater was directly inserted into the test tank without a steam generator. The water content of the 5% salt solution
It was found that the weight was reduced by 7 kg / hour.

Of the 0.3 kg / hour steam generated by the steam generator, the portion other than the dew condensation in the pipe is supplied to the test tank as steam.

Here, the amount of water per hour condensed in the pipe is as follows: the latent heat of condensation of water at 100 ° C. is 2263 kJ /
Since it is kg, it is 0.23 kg / hour from Expression 9. In Equation 9, K (kg / hour) is the amount of water per hour for dew condensation, and q is the latent heat of condensation of water at 100 ° C.

[0055]

(Equation 9)

Therefore, the steam supplied to the test tank is calculated by subtracting the dew condensation from the steam generated by the steam generator. In the above case, the amount of water vapor supplied into the test tank is 0.07 kg / hour.

Therefore, under the above conditions, the reduced steam is supplemented by the steam sent from the steam generator to the test tank.

FIG. 4 is a characteristic diagram showing the change over time in the test chamber temperature of Example 1 and Comparative Example 1 of the present invention, and compares the results obtained by measuring the time required for the test chamber temperature to rise. Comparative Example 1 is a conventional type in which the test tank is a double tank, water is supplied between the tanks, and the water is heated by a heater. FIG. 5 is a diagram showing the positions of the temperature measurement points. The temperatures were measured at five points a to e in the figure. In Example 1, the time required to raise the temperature inside the test tank from the outside air temperature to the test temperature was shorter than in Comparative Example 1.

FIG. 6 is a perspective view of a main part of a second embodiment of the present invention. In the second embodiment, instead of the steam pipe in the first embodiment, the steam coming in from the steam inlet above the steam inlet (2) is brought into contact with the steam above the steam inlet (2), and the jet direction of the steam is changed to the lower side and the side of the test tank. A plate (5) that can be oriented is provided. The plate (5) is held by a support bar provided on the bottom surface of the test tank.

A part of the water vapor that has come into contact with the plate (5) is condensed on the lower surface of the plate and radiates heat into the test tank. In order to prevent the water vapor supplied into the test tank from directly contacting the test piece, the jet direction of the water vapor is directed downward and to the side of the test tank.

FIG. 7 is a partially cutaway perspective view showing a third embodiment of the present invention. In the third embodiment, instead of the plate of the second embodiment, a hollow box (16) having no bottom surface is provided above the steam inlet, and the water vapor jetted upward from the steam inlet contacts the box (16). It is provided so that the jet direction of the steam can be directed to the lower side and the side direction of the test tank.

In Examples 2 and 3, the time required to raise the temperature in the test tank to the test temperature was about the same as that in Example 1.

FIG. 8 is a spray amount distribution chart of Example 1, Example 2, Example 3, and Comparative Example 2 of the present invention. FIG. 8 (a)
8B is a spray amount distribution diagram of the first embodiment, FIG. 8B is a spray amount distribution diagram of the second embodiment, FIG. 8C is a spray amount distribution diagram of the third embodiment, and FIG. Comparative Example 2 is a conventional type in which a heater is directly placed in a test tank. Here, the numerical value in the circle indicates the amount of collection per hour (mL) for each 80 cm ^{2 of} horizontal collection area.
/ Hour).

Further, Table 1 shows the variation in the temperature in the tank, the average spray amount and the spray distribution, the measured salt concentration of the sampled liquid, the measured specific gravity, and the measured specific gravity in Example 1 and Comparative Example 2 of the present invention. It is a comparison list of the calculated salt concentration. The measured salt concentration is a value obtained by measuring the salt concentration of the collected liquid using a digital salt concentration meter. The specific gravity of the collected liquid was measured using Bohr's specific gravity meter, and was converted to a specific gravity at 25 ° C. Further, the salt concentration was calculated from the specific gravity from the explanatory diagram 2 of JIS Z 2371: 1994.

[0065]

[Table 1]

In Example 1, the specific gravity measured value of the collected liquid and the salt concentration calculated from the specific gravity measured value conformed to the rule that the specific gravity measured value was 1.029 or more and 1.036 or less at 25 ° C. The salt concentration calculated from the specific gravity measurement is
5.0 ± 0.5 wt%, that is, within the range of 50 ± 5 g / L. The spray distribution was within the specified range of 1.5 ± 0.5 mL / hour. Further, the variation of the temperature distribution was smaller than that of Comparative Example 2. On the other hand, in Comparative Example 2, the specific gravity exceeded 1.045, and the specific gravity could not be measured. Further, both the spray distribution and the temperature distribution were worse than those in Examples 1, 2 and 3.

The salt concentration and specific gravity of the collected liquid of Comparative Example 1 were the same as those of Example 1, and the temperature variation and the spray distribution were the same as those of Comparative Example 2. Further, the heater capacity was 3.0 kW in Comparative Example 1, and 1.5 kW in Comparative Example 2.
On the other hand, in the first, second, and third embodiments, the required amount of heat is small, so that only 1.0 kW is required. That is, from the viewpoints of shortening the time until the start of the test, uniformity of temperature and spraying, salt concentration and specific gravity, and required calorific value, Examples 1, 2 and 3 are conventional types. It can be said that it is overall better than Example 1 and Comparative Example 2.

[0068]

As described above, in the salt spray test apparatus of the present invention, the steam generator and the steam inlet, and the means for ejecting steam toward the bottom and / or the side of the test tank are provided. Since the temperature in the test tank is heated by using the temperature, the test temperature can be maintained while keeping the humidity in the test tank constant. Therefore, the test can be performed while keeping the salt concentration of the spray mist constant. For this reason, the salt concentration and the specific gravity of the collected liquid can be set within the specified ranges.
Further, the uniformity of the salt concentration can be improved. Further, the uniformity of the temperature distribution in the test tank can be improved. Therefore,
The reliability of the corrosion test can be improved.

Further, the salt spray test apparatus of the present invention has the above-described structure, so that the temperature can be raised quickly and the required heat quantity is smaller than that of the conventional type. Further, there is no need to use a double test tank, and the test tank production cost is low.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing an example of a configuration of a salt spray test apparatus to which the present invention is applied, partially cut away.

FIG. 2 is a perspective view of a main part in a test tank according to the first embodiment of the present invention.

FIG. 3 is a perspective view of a main part of a steam supply part according to the first embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a change over time in a test tank temperature in Example 1 and Comparative Example 1 of the present invention.

FIG. 5 is a view showing a position of a temperature measurement point.

FIG. 6 is a perspective view of a main part of a second embodiment of the present invention.

FIG. 7 is a perspective view of a main part of a third embodiment of the present invention, partially cut away.

FIG. 8 is a spray amount distribution diagram of an example of the present invention and Comparative Example 2.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 steam generator 2 steam inlet 3 steam pipe 4 steam outlet 5 plate 6 water filter 7 air saturator 8 spray nozzle 9 spray tower 10 test tank 11 test piece 12 salt water spray test device 13 solution supply tank 14 exhaust port 15 sampling 16 boxes

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 17/00 JICST file (JOIS)

Claims (5)

(57) [Claims] (1) a steam generator for generating steam;
(B) a steam inlet connected to the steam generator and penetrating the bottom of the test tank; (c) keeping the temperature in the test tank within a certain range, and keeping the salt concentration of the sampled liquid within a certain range. A salt water spray test apparatus having means capable of jetting steam from the steam inlet into the test tank toward the bottom and / or the side surface of the test tank so as to keep the temperature of the test chamber. 2. A means for discharging steam from the steam inlet into the test tank toward a bottom and / or a side surface of the test tank, wherein the means starts from the steam inlet and starts the test tank. 2. One or more pipes provided below the inside of the test tank, the plurality of pipes having a plurality of holes facing downward and / or in the side direction of the test tank so as to blow water vapor toward a bottom surface of the test tank. The salt spray test apparatus according to the above. 3. The method according to claim 1, wherein the means for discharging steam from the steam inlet into the test tank toward a bottom and / or a side surface of the test tank includes a steam jetted upward from the steam inlet. A plate or a box without a bottom provided above the steam inlet so that the steam can be directed downward and to the side of the test tank in contact with the test tank. 2. The salt spray test apparatus according to 1. 4. The method according to claim 1, wherein the amount of steam supplied from the steam generator into the test tank is equivalent to the amount of steam lost due to condensation in the test tank. Salt spray test equipment. 5. The salt spray test apparatus according to claim 1, further comprising a filter for purifying water supplied to the steam generator.