JPH03211226A - Fused salt washing device for hot temperature steel plate - Google Patents

Abstract

PURPOSE:To obtain a cooled steel plate having uniform quality, a little strain, good shape and a little remained fused salt by injecting washing water and gas from upper and lower parts after injecting the fused salt from upper and lower faces of the high temp. steel plate conveyed with a roller table. CONSTITUTION:The high temp. steel plate 14 is conveyed with the conveying roller table composing of plural rollers 13. The fused salt supplied from a fused salt bath 16 with pumps 10, 11 is injected from nozzles of cooling nozzle headers 1, 2 set at upper and lower parts in the conveying roller table onto the upper and lower faces of this steel plate 14. By this method, the above high temp. steel plate 14 is uniformly cooled. A fused salt washing device is set in downstream of this cooling device, if necessary, plural devices are set in series, to wash and remove the fused salt stuck to the surface of cooled steel plate 14. This washing device has constitution for injecting circulated washing water or new washing water from water injecting nozzles 18a, 18b, 20a, 20b for washing the fused salt with a water pump 22 from a water vessel 27 and gas from gas injecting nozzles 19, 20. By this method, the cooled steel plate having uniform temp. distribution, stable shape, and a little of variation in the quality in the plate and the remained fused salt, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a molten salt cleaning apparatus for high temperature steel plates using a molten salt jet stream as a cooling medium.

(Conventional technology) In recent years, in the plate manufacturing process, research has been actively conducted on temper cooling processes that combine controlled rolling and controlled cooling immediately after rolling, with the aim of reducing alloying elements, saving heat treatment, and developing new steel types. The online controlled cooling system has already been put into practical use and is in production.

As such a cooling device, for example,
A method and device for cooling a thick steel plate that can be cooled online in a not-so-wide area, disclosed in Japanese Patent Publication No. 415; , A cooling method and apparatus for producing a thick steel plate with good flatness, which can be assembled immediately after the cooling process is completed.■ Direct impingement of the upper surface cooling water flow on both ends of the steel plate in a shielding tank disclosed in Japanese Patent Application Laid-Open No. 58-32511. prevent,
Cooling method and device for obtaining a steel plate with small distortion, ■ Japanese Patent Application Laid-open No. 5
There is a uniform cooling device disclosed in Japanese Patent Publication No. 9-16617, which performs cooling while being constrained by a plurality of upper and lower rollers, and has a drainer provided for each cooling unit. All of these cooling methods and devices use water (boiling liquid) as a cooling medium.

Furthermore, recently, these cooling methods and their cooling devices have not yet been able to sufficiently solve the problem of distortion after cooling, and it takes a lot of time and money to straighten it. No. 62-54507,
It is described that before cooling, the surface of a hot steel plate to be cooled is formed with substantially uniform roughness in the width direction of the plate to achieve uniform cooling.

On the other hand, an example of using molten salt as a cooling medium is
JP-A-104433 discloses an apparatus for continuous heat treatment of metal strips comprising the steps of preheating, heating, soaking, and cooling, which utilizes the sensible heat of the strip in a cooling tank as a heat source for the preheating tank; There is a cooling device disclosed in Japanese Patent No. 59-162229 that uses a refrigerant heated to a high temperature by the sensible heat of a metal strip to raise the temperature of gas in a heat transfer tube to remove water adhering to the metal strip. In both of these methods, the material to be cooled is immersed in a molten salt bath to cool or heat it.

(Problems to be Solved by the Invention) Regarding cooling devices for high-temperature W4 plates, there are many techniques that use water as a refrigerant as described above, but they are still insufficient in terms of temperature control and shape control.

In other words, a steel plate subjected to controlled rolling is forcedly cooled from a high temperature range of around 750 to 850°C to an arbitrary temperature below 600°C, but the steel plate is cooled uniformly without cooling the entire steel plate while maintaining the shape of the steel plate during cooling. Since it is necessary to stop cooling at a predetermined temperature, research, development, and improvement of various cooling control methods and devices during cooling are continuing. Research is also being conducted on methods to uniformly cool the material by controlling the surface properties and roughness of the material to be cooled. However, no method or device for cooling high-temperature steel sheets using a refrigerant such as molten salt has been found other than the method and device for cooling a high-temperature steel plate using an immersion method such as the metal strip described above.

All of the conventional cooling techniques mentioned above have the following problems.

Namely, ■Japanese Patent Application Publication No. 51-61415, ■Japanese Patent Application Publication No. 54-124864, and ■Japanese Patent Application Publication No. 58-32511.
The devices described in Japanese Patent Application Laid-Open No. 59-16617 all have fundamental problems because they use water, which is a boiling type cooling medium, as the cooling medium. When a cooling medium that causes a boiling phenomenon is used to cool a hot steel plate, the temperature, water volume, impingement pressure, water flow type, etc. from the cooling medium side can be changed during the cooling phenomenon from the side of the material to be cooled. It is strongly influenced by temperature imbalance before cooling, shape, surface texture (scale and surface roughness), etc. These effects combine to cause variations in the cooling rate within the hot steel plate, resulting in
It is well known that the temperature immediately after cooling becomes uneven and the shape of the steel sheet becomes unstable, resulting in variations in material quality and defective shapes. Because of this problem with the basic cooling phenomenon, no matter how much we devise cooling methods and equipment, it is impossible to fundamentally solve the problem.As a result, the straightening process of the steel plate after cooling requires a lot of effort and cost. It is said that Also, when the steel plate manufactured in this way is cut into strips for processing,
There is also the problem that bending occurs again.

In order to solve these problems,
In Publication No. 07, etc., control is performed from the side of the cooled material, that is,
Attempts are being made to form the surface of the steel plate to a nearly uniform roughness to achieve uniform cooling. However, as long as water is used as a cooling medium, the basic boiling cooling phenomenon remains the same, so there are subtle differences in the roughness formed on the surface of the steel sheet and the scale distribution generated before cooling begins after rolling. (It is difficult to make the surface texture of the material uniform no matter how you adjust it.) This causes variations in the boiling phenomenon during cooling.
There will be variations in the cooling rate. As a result, the temperature after cooling becomes non-uniform and the shape of the steel sheet becomes unstable, making it impossible to eliminate variations in material quality and defective shape.

As described above, using water, which is a boiling type cooling medium, as a cooling medium has too many problems in terms of material and shape for stable cooling.

Therefore, it is conceivable to use a non-boiling type cooling medium that does not cause boiling while cooling the high-temperature steel plate. Molten salt is often used as the non-boiling cooling medium. ■Unexamined Japanese Patent Publication 1973-
104433, Japanese Patent Application Laid-Open No. 59-162229, etc., the material to be cooled is immersed in a molten salt tank to heat or cool it. When cooled by immersion in the steel plate, the temperature of the upper part of the bath increases due to convection in the molten salt bath, and heat transfer is smaller at the upper end of the steel plate than at the lower end, resulting in non-uniform cooling. Furthermore, if immersion cooling is performed horizontally, heat transfer will be different between the upper and lower surfaces, resulting in poor shape due to variations in material. Moreover, even if gas is blown into these and the molten salt bath is stirred, uneven cooling is unavoidable even though heat transfer may increase slightly.

The present invention has been made in view of the above points, and it is possible to uniformly cool the steel plate without pre-treating the high-temperature steel plate, and without overcooling even if there are temperature variations in the high-temperature steel plate before cooling. We provide a molten salt cleaning device for high-temperature steel plates, which aims to achieve uniform temperature distribution after cooling, stabilize the shape of the steel plate, reduce material variation within the steel plate, and significantly reduce the straightening rate.

(Means for Solving the Problems) The present invention is a molten salt cleaning device disposed on the rear surface of a cooling device in which a molten salt injection mechanism for cooling high temperature steel plates is disposed above and below a roller table for conveying high temperature steel plates, comprising: A plurality of water jet nozzles and gas jet nozzles for cleaning molten salt adhering to the surface of the cooled steel plate are provided at the upper and lower parts of the roller table for conveying the steel plate cooled by the cooling device, respectively, facing the cooled steel plate. This is a molten salt cleaning equipment for high temperature steel plates. Furthermore, the present invention provides a molten salt cleaning device disposed on the rear surface of a cooling device in which a molten salt injection mechanism for cooling high temperature steel plates is disposed at the upper and lower parts of a roller table for conveying high temperature steel plates, the molten salt cleaning device disposing the molten salt on the surface of the cooled steel plate. A plurality of cleaning water jet nozzles and gas jet nozzles are provided at the top and bottom of the roller table for conveying the steel plate cooled by the cooling device, facing the cooling steel plate, and the conveying roller is arranged so that the molten salt cleaning water can be recovered. A molten salt cleaning apparatus for high temperature steel plates, comprising a molten salt cleaning water circulation tank disposed at the bottom of the table and a molten salt cleaning water circulation path disposed so as to be usable by the molten salt injection mechanism for cooling high temperature steel plates. and
In this case, it is preferable to connect a plurality of molten salt cleaning devices for high-temperature steel sheets in series.

(Function) First, the cooling phenomenon of high-temperature steel sheets will be explained by comparing the case of cooling with molten salt (non-boiling type cooling medium) and the case of cooling with water (boiling type cooling medium).

In the case of water cooling in which water is injected onto the surface of a high-temperature steel plate, the cooling water cools the high-temperature steel plate while boiling. Its cooling curve is slow cooling,
After passing through three stages of rapid cooling and slow cooling, the boiling curve is composed of a film boiling region, a transition boiling region, a nucleate boiling region, and a non-boiling region from high temperature to low temperature, respectively. In other words, the cooling curve and boiling curve are in the high temperature region...film boiling region (stable state covered by a vapor film), and the intermediate temperature region...transition boiling region (unstable state in which vapor film boiling and nucleate boiling coexist). Low temperature range: Nucleate boiling range (maximum heat flux): Non-boiling range (below 100°C). However, the temperature range is affected by the flow type of cooling water, water temperature, flow rate, pressure, surface properties of the material to be cooled (scale adhesion amount and nature, roughness, etc.), size, etc.

Therefore, approximately 700
If it is necessary to start cooling from a temperature of ℃ or higher and stop it at an arbitrary temperature of about 300 to 600℃ (equivalent to a medium temperature range),
Cooling is stopped in the transition boiling region where the cooling capacity rapidly changes, and this transition boiling region is a temperature region that is sensitively affected by the cooling water side and the cooled material side.

As described above, when a boiling type cooling medium such as water is used, precise and careful temperature control is required for controlled cooling of high-temperature steel sheets, and a fundamental solution cannot be achieved.

Therefore, if a non-boiling type cooling medium (for example, molten salt) that does not boil even in high, medium, and low temperature ranges is used for such controlled cooling, the steel plate can be reliably heated to a temperature close to the cooling stop temperature. Steel plates are the most stable material because they can be cooled, do not become overcooled, and can stop cooling with a uniform temperature distribution. In addition, since boiling does not occur, uneven cooling is small, and the shape of the steel sheet is stable during and after cooling.

As a result of basic research using molten salt for controlled cooling of high-temperature steel sheets, the inventors of the present invention found that molten salt does not boil within the controlled cooling temperature range of high-temperature steel sheets. The entire surface of the steel plate was wetted with molten salt, the steel plate was cooled without any boiling phenomenon, and the shape of the cooled steel plate was good. A high-temperature steel plate with a temperature of approximately 700°C or higher is cooled to 0.
When performing a cooling stop at a temperature of 0 to 300℃, approximately 20
Nitrates used in the temperature range from 0 to 600 °C (e.g.
Sodium nitrate [NaNOs] or potassium nitrate [
The simple salt of KNO□l or sodium nitrate [NaN0
s] and potassium nitrate (a mixed salt of KNOsl or a mixed salt of nitrate and sodium nitrite [NaN02]), etc., is desirable. It does not boil, it is stable even when used repeatedly for cooling, it can be transported through piping with a pump, etc., and injected from a cooling nozzle, except that it is a high-temperature fluid, and it can be injected from a cooling nozzle. This is because the steel plate can be easily cleaned with water, and the cooling device can be constructed from ordinary steel. However, nitrates are classified as dangerous substances, so care must be taken when handling them. Note that the melting point temperature of these nitrates changes depending on the mixing ratio. The melting point is NaN0i: 31 for a single salt.
0℃, KNol: 338℃, depending on the mixing ratio 21
The temperature can be lowered to 8°C. Therefore, it can be used up to a molten salt injection temperature of about 250°C. If a molten salt jet stream with a lower temperature is required, a melting point of about 140°C can be obtained by adding about 50% NaNOx to NaNOx and KNO, and the molten salt jet temperature can be lowered to 200°C. It is also possible to use the temperature at about ℃.

Although nitrate is used as an example here, a non-boiling cooling medium may also be used instead.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail along with their effects with reference to the drawings.

FIG. 1 shows an example in which the high-temperature steel plate molten salt cleaning apparatus of the present invention is arranged together with a high-temperature steel plate cooling apparatus in front thereof, and FIG. 2 shows an example in which the high-temperature steel plate molten salt cleaning apparatus is arranged in multiple stages.

In the cleaning device of the present invention, the cleaning water containing molten salt used for cleaning can be sprayed by the water pump 22 through the water pipe 29 and from the spray nozzle 28 toward the bath surface of the molten salt bath 16. ing. However, the cleaning water circulation system of the molten salt cleaning apparatus shown in FIGS. 1 and 2, which is not sprayed while the high-temperature steel plate is being cooled, uses a water tank 27 provided at the bottom of a roller table composed of a large number of rollers 13.
Open the wash water switching valve 30 and turn the washing water switching valve 31 on.
is closed, the water pump 22 is started and the water is sent from the water suction pipe 23 to the water supply pipes 24, 25, 29, and the cleaning water jet nozzles 18a, 18b, which are disposed at the upper and lower parts of the steel plate 14.
It is injected toward the steel plate 14 from 20a and 20b. The sprayed washing water 26 on the upper surface of the steel plate is discharged from both ends of the steel plate 14 and collected in a water tank 27, and the sprayed washing water on the lower surface of the steel plate is directly collected in the water tank 27 and is circulated through the pump 22 again. When the content of molten salt increases, the repeatedly used cleaning water is removed by opening the cleaning water switching valve 31, closing the cleaning water switching valve 30, starting the water pump 22, and discharging the water from the water suction pipe 23 to the front. The water is sent to the water pipes 24, 25 of the cleaning device and the water pipe 29 of the cooling device, which are arranged in the same manner, and used to control the temperature of the cleaning water or the molten salt of the cooling device.

The molten salt cleaning device in the arrangement shown in FIG. 1 is a cooling device for high temperature steel plates and a molten salt cleaning device for high temperature steel plates of the present invention installed on the rear side thereof. Opposing the steel plate 14 at the upper and lower parts of the roller table, the inlet side is inclined in the advancing direction of the steel plate 14 to provide a cleaning water jet flow and the gas reverse jet stream, and the outlet side is inclined in the forward moving direction of the steel plate 14. A plurality of water tanks 27 are provided with a plurality of spray nozzles that spray a cleaning water jet stream and a gas jet stream, and are arranged at the bottom of the roller table for conveying the steel plate. It is used to completely clean and remove molten salt remaining on the board surface. The gas injection muzzles 19, 21 disposed on the inlet and outlet sides are cleaning water jet nozzles 18a, 18, which play the role of preventing backflow and outflow of the cleaning water jet.
b, 20a, and 20b are for cleaning molten salt remaining on the cooling steel plate, and each may be arranged in multiple stages.
Cleaning water jet nozzles 18a, 18b.

20a and 20b are predetermined (100 to 500fflI11
), the cleaning water 26 collides with each other, and the upper surface of the cooling steel plate is discharged from both ends of the plate into the water tank 27, while the lower surface remains in the water tank 27. It falls within 27 seconds. The cleaning water dropped into the water tank 27 and collected is pumped up again by the pump 22 and used as a cleaning water jet. Cleaning water jet nozzle 1
8a, 18b, 20a, and 20b each show two rows of gas jet nozzles 19 in FIGS. 1 and 2, but they may be arranged in one row or in two or more rows. .21 is installed only above the cooling steel plate, and serves both to prevent backflow of washing water and to dry the cooling steel plate. Since there is no water in the lower part, it can be easily dried without using a gas jet. In this way, it is possible to reuse the same water jet for cleaning, but as the frequency of use increases, the content of molten salt in the cleaning water increases, and there is a risk that the molten salt will remain on the cooling steel plate, so the water tank 27 is As shown in Figure 2, the washing water switching valve 30.
It is also possible to advance the zone through which the cleaning water is sent, and as the cleaning zone moves closer to the cooling device, the cleaning water can be used as cleaning water with a higher molten salt content. The final cleaning of the cleaning equipment always provides fresh water and can also eliminate residual molten salts. Furthermore, the cleaning water used in rough cleaning can be sprayed into the cooling device installed in the front with a spray nozzle 28 or the like and used to control the temperature of the molten salt in the cooling device, or can be used to remove water and recover the molten salt. . The distance from the cleaning device to the cooling device should be close to the top where the cooled steel plate is transported, but it is also desirable to set it at least the maximum length of the steel plate to be cooled.The reason for this is that This is because when cleaning is performed immediately after cooling, if a large amount of cleaning water were to enter the molten salt tank of the cooling device through the upper surface of the steel plate, a steam explosion would occur, which would be very dangerous. Therefore, it is necessary to avoid cooling and cleaning the same steel plate at the same time.

Next, cleaning water jet nozzles 18a, 18b, 20a.

The angle of inclination of the gas jet nozzle 20b and the gas jet nozzle 19.21 is 30 degrees or more and 60 degrees with respect to the vertical direction of the steel plate to be cleaned.
If it is less than 30 degrees, the cleaning water will bounce back and scatter even if a gas jet is applied, and if it exceeds 60 degrees, the distance of the jet will be large and it will not be effective unless the nozzle is brought close to the steel plate. In the case of cleaning water jets, a large number of flat spray nozzles are arranged so that the collision part jets are jetted in an unbroken curtain shape parallel to the width direction of the steel plate. 5-3.0kg/
Inject at a pressure in the range of cm"-G. In that case, the injection flow rate is 50 to 300 I2/m/m of injection header length.
+++in, the flow rate of the cleaning water increases or decreases depending on the state of molten salt adhering to the steel plate. Injection pressure of 0.5kg/c is -G
If it is less than 3.0 kg/cm, sufficient force will not be obtained to remove molten salt adhering to the steel plate surface.
- G is not preferable because it is disadvantageous in terms of cost. Note that the water jet nozzle for cleaning may be a slit nozzle. In the case of a primary gas jet flow, both the one person exit side are used to prevent backflow of cleaning water and to prevent drying. Therefore, the inlet side is in front of the cleaning water jet nozzle 18, and the outlet side is in the rear of the cleaning water jet nozzle 20, respectively. The nozzle may be a continuous through hole or an intermittent slit nozzle in the longitudinal direction of the ladder pipe, or may be a continuous gas curtain jet). The nozzle width of the slit nozzle is 0.5~3.0+nm, and the gas injection pressure is 0.1kg/
A range of cm'-G to 1.0 kg/cm"-G is appropriate. If the nozzle width is less than 0.51, even if the gas injection pressure is increased, the mass will be small and the power to remove leaking cleaning water will be insufficient. If the thickness exceeds 3.0 mm, the gas injection flow rate becomes too large, resulting in large cost losses.The gas injection pressure is 0.1 kg/cm"-6 If it is less than 1.0k, it will not have enough power to remove leaking washing water and the drying power will be weak.
g/cm'' - G exceeds the risk of washing water scattering and being unfavorable from a cost perspective.It is desirable to keep the distance between the zero-order steel plate and the nozzle close from the standpoint of molten salt removal efficiency, but warping of the cooling steel plate, etc. 300±20011 on steel plate to avoid the influence of
The nozzle may be installed within the range of IIll, and the nozzle may be lowered by a lifting device when the steel plate begins to pass.

The arrangement relationship between the cleaning water jet nozzle 18 and the gas jet nozzle 19 on the inlet side of the cleaning device is such that the gas jet nozzle 19 is installed in front of the cleaning water jet nozzle 18, and the cleaning water jet nozzle 19 is installed in front of the cleaning water jet nozzle 18 on the cleaning device outlet side. Arrangement relationship between the nozzle 20 and the gas jet nozzle 21 The jet nozzle 21 is installed behind the cleaning water jet nozzle 20, and the interval between each is 100 to 500 mm depending on the size of the ladder pipe to the jet nozzle. If the zero interval, which should be in the range of , exceeds 500 mm, the effect of the gas jet flow will decrease.

With this configuration, each injection pressure can be reduced, reducing running costs, reducing the amount of molten salt deposited on the cooling steel plate, reducing the amount of molten salt carried out, and making it easier to clean the deposited molten salt. effective.

The steel plate cooled in this way had such good flatness that no warping appeared in measurements, and was hardly affected by scale generated on the surface of the high-temperature steel plate.

Regarding the materials of the main parts of the molten salt cleaning device of the present invention, in the case of molten salts such as nitrates to be cleaned in the present invention, problems related to corrosion are particularly small (although construction with ordinary steel may be sufficient). , but not limited to, molten salt resistance
Any material may be used as long as it is durable. Also, from the viewpoint of the environment during cleaning, it is desirable to construct a hood or the like above the molten salt cleaning equipment to perform exhaust treatment.

Although molten salt cleaning is performed on a transport roller table, cooling may be performed while being transported on rollers, in a stationary state, or while being reciprocated.

The cooling bag shown on the left side of Figure 1! is used to heat the molten salt to a predetermined temperature and use a molten salt pump 10.11 (not shown) to cool the high-temperature steel plate 14 that has retained rolling heat after rolling or has been heated for the purpose of cooling. The molten salt removal pump was started, and the molten salt jet streams from the upper and lower jet cooling nozzle headers 1.2 and the molten salt jet nozzles 6a, 6b, 8a, and 8b were set to predetermined flow rates and jetted. That is,
The molten salt was sent to upper and lower main pipes 3 and 4 in the tank by pumps 10 and 11, distributed and supplied to upper and lower cooling nozzle headers 1 and 2, and injected from the nozzles. The heater 5 in the header 1 was previously energized to generate heat to a set molten salt temperature to dissolve the molten salt accumulated at the bottom of the header 1 and the molten salt in the injection nozzle. Similarly, a molten salt jet stream and a gas jet stream were injected from nozzles at the inlet and outlet sides. In the case of this example, the molten salt contains nitrate (NaN0z+KNOs mixed salt: 5
0+50wt%) was used. When a predetermined molten salt injection flow rate is set, a steel plate 14 (thickness 20 mm, width 1000+ mm, length 40
00 mm) was inserted from the inlet side of the cooling device, and continuous cooling was performed while reciprocating on the roller with a molten salt jet stream at a constant jet flow rate set at a temperature of 300°C.

The type of molten salt injection nozzle used for cooling was a pipe nozzle, the jet type was a rod laminar flow, and the nozzle distance was 1000 mm at the top and 100+ nm at the bottom from the high-temperature steel plate surface. The molten salt injection flow rate is 701/rrl”・win (
Upper part: Lower flow rate is 700 at the upper part! , /rr? −
The cooling time was approximately 40 seconds, and the cooling end temperature was approximately 375°C. During this time, temperature fluctuations in the molten salt caused by cooling of the high-temperature steel plate were controlled by a heater or heat exchange equipment installed in the molten salt tank. The upper and lower molten salt injection flow rate ratios are determined by the type and arrangement of the installed injection nozzles, the distance between the injection nozzles and the steel plate, and the like. In addition, the molten salt temperature, injection flow rate (flow rate control is performed at a constant injection flow rate or by continuously increasing or decreasing the injection flow rate in a stepwise manner), cooling time, etc. are determined based on the cooling start temperature based on the information from the thermometer 17. and the required material (for example, control of strength and control of the formation ratio of ferrite structure and bainite structure in the thickness direction of the steel sheet), and is controlled by the operation control device 12. In addition, the molten salt injection nozzles 6a, 6b, 8a, and 8b that prevent molten salt from flowing out of the cooling device are flat spray nozzles, and the injection pressure is 1.0 kg/cm2-G and the flow rate is 9
0I2/rn-min, gas injection nozzles 7a, 7b.

9a and 9b are slit nozzles, and the nozzle width is 2IIll.
I, the injection pressure was set to Q, Ikg/cm''-G, and the inclination angles of these nozzles were all set to 45 degrees with respect to the vertical direction of the steel plate 14.

When the time approaches for cooling to end in this way,
Predetermined amounts of gas jet flow and cleaning water jet flow of the molten salt cleaning device shown in the right side of FIG. 1 or FIG. 2 are injected in advance, and the steel plate 14 that has been cooled is extracted from the cooling device
Molten salt adhering to the steel plate was cleaned by passing through one cleaning device. A cleaning water jet nozzle 18a is installed in the cleaning device.
.

18b, 20a, and 20b are flat spray nozzles (two rows arranged on both the inlet and outlet sides), the injection pressure is 1.5 kg/cm"-G, and the flow rate is 12042/cm"-G.
In m-win, the gas jet nozzle 19.21 is a slit nozzle, the nozzle width is 2 mm, and the injection pressure is 0.2 kg/
cm''-G, and the inclination angles of these nozzles were all set at 45 degrees with respect to the vertical direction of the steel plate 14.

As a result, it is possible to stably obtain a good plate shape with excellent flatness during cooling and cleaning of high-temperature steel plates, and to obtain a cooled steel plate that is homogeneous and has good material quality, and has no residual molten salt. was completed.

(Effects of the Invention) According to the present invention, a cooled steel plate free of residual molten salt, which is made of a homogeneous material, has a good plate shape with small distortion, and is free of residual molten salt can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the molten salt cleaning apparatus of the present invention, and FIG. 2 is a diagram showing an embodiment arranged in multiple stages. l... Ladder to upper injection cooling nozzle, 2... Ladder to lower injection cooling nozzle, 3... Upper main piping, 4...
Lower main piping, 5... Heater for dissolving molten salt, 6a. 6b... Molten salt injection nozzle, 7a, 7b... Gas injection nozzle, 8a, 8b... Molten salt injection nozzle, 9a. 9b... Gas injection nozzle, 10... Upper molten salt pump, 11... Lower molten salt pump, 12... Operation control device, 13... Conveyance roller, 14... Steel plate,
15...19...Gas jet flow nozzle, 20a, 2
0b...Cleaning water jet nozzle, 21...Gas jet nozzle, 22...Water pump, 23...Water suction pipe, 2
4.25 Water pipe, 26...-washing water, 27... Water tank,
28... Spray nozzle, 29... Water pipe, 30.
31...Washing water switching valve.

Claims (3)

[Claims] (1) A molten salt cleaning device installed at the rear of a cooling device in which a molten salt injection mechanism for cooling high-temperature steel plates is installed above and below a roller table for conveying high-temperature steel plates, and the molten salt cleaning water adhered to the surface of the cooled steel plate. A molten salt cleaning apparatus for a high-temperature steel plate, characterized in that a plurality of jet nozzles and gas jet nozzles are provided at the upper and lower parts of a roller table for conveying the steel plate cooled by the cooling device, respectively, facing the cooling steel plate. (2) A molten salt cleaning device installed at the rear of the cooling device, which has a molten salt injection mechanism for cooling high-temperature steel plates installed above and below the roller table for conveying high-temperature steel plates, which cleans the molten salt that has adhered to the surface of the cooled steel plate. A plurality of water jet nozzles and gas jet nozzles are provided at the upper and lower portions of the roller table for conveying the steel plate cooled by the cooling device, facing the cooling steel plate, and the conveying roller table is configured to be capable of recovering water for molten salt cleaning. A molten salt cleaning device for a high temperature steel plate, comprising a molten salt cleaning water circulation tank disposed at a lower portion and a molten salt cleaning water circulation path disposed so as to be usable by the molten salt injection mechanism for cooling the high temperature steel plate. (3) A molten salt cleaning device for a high temperature steel plate, characterized in that a plurality of the molten salt cleaning devices for a high temperature steel plate according to claim 2 are connected in series.