KR100456466B1 - An apparatus for removing the foam in cleaning line of strip - Google Patents

Abstract

The present invention relates to a method and apparatus for removing bubbles generated in a steel plate cleaning line. In the method for removing bubbles generated in a circulating storage tank 111, the foam of the circulating storage tank 111 is washed with a washing liquid. In addition, the step of introducing into the parcel tank (11) having an internal space of a predetermined size; The blast blades 22 installed in the blast chamber 21 are rotated by the motor member 23 of the blast chamber 21 having the suction port 21a formed on the lower surface corresponding to the water surface of the defoaming tank 11. Driving to firstly blow bubbles forced into the blast chamber (21); The foam guided to the rear end side by the suction force of the suction blower 50 installed at the rear end of the defoaming tank 11 passes through the porous plates 36a and 36b installed at least one perpendicularly to the rear end of the defoaming tank 11. To secondary removal; Circulating and supplying the cleaning liquid from which the bubbles are removed in the defoaming tank (11) into the circulation storage tank (111) by circulating pump (19); including only alkaline bubbles generated during the cleaning of the steel sheet. It is possible to reduce the consumption rate of the cleaning solution and to prevent the surrounding environment and equipment pollution.

Description

Defoaming device of steel plate cleaning line {AN APPARATUS FOR REMOVING THE FOAM IN CLEANING LINE OF STRIP}

The present invention relates to a method and apparatus for removing bubbles generated in a steel sheet cleaning line. More specifically, the present invention relates to rolling oil, iron, and reaction products attached to the surface of a steel sheet during rolling and pickling in a cold rolling line of a steel mill. By detonating and recirculating alkaline foams generated during the process of cleaning iron ore gum (stearic acid soda), etc., the consumption rate of the cleaning solution can be reduced, and the surrounding environment and equipment pollution caused by the discharge of alkaline solution foam can be reduced. It is related with the defoaming apparatus of the steel plate cleaning line which can be prevented.

In general, the lines for producing cold-rolled products in cold mills of steel mills are hot dip galvanized line after pickling rolling and hot dip galvanizing, followed by continuous annealing line and zinc and tin electro galvanizing line and electrolytic plating. There are also Seokdo zinc plating line.

These processes must undergo a cleaning process to clean the surface of the steel sheet as shown in FIG. 1 (a) prior to surface treatment of the steel sheet, which is a foreign material such as rolling oil, hydraulic oil and iron powder on the surface of the steel sheet during cold rolling. 100 to 200mg / m ² is attached, and these deposits adversely affect the adhesion and corrosion resistance of the plating in the post-treatment plating process, and increase the porosity, so that the high temperature before annealing the steel sheet. Washing was performed using an alkaline solution (NaOH 1-5 wt%). In order to maximize the cleaning efficiency, the cleaning process is a combination of alkaline cleaning, electrolytic cleaning and brush cleaning.

That is, the alkaline cleaning during the cleaning process is slightly different depending on the characteristics of the cold rolling line, but the alkaline cleaning tank filled with alkaline solution of about 70-80 ℃ in the case of alkaline cleaning, which is the primary washing step, one-way ) Or by spraying the cleaning solution on the surface of the steel sheet.

In the case of the electrolytic cleaning, which is the secondary cleaning step, the steel sheet passes through a pair of electrodes 121 installed in the electrolytic cleaning tank 120 containing the alkaline cleaning liquid having high electrical conductivity, and the steel sheet to be electrolytically cleaned By applying a voltage to the electrode and the metal having good durability in the conductive and alkaline solution as another electrode, the rolling oil and fine iron powder strongly adhered to the surface of the steel sheet by the electrolysis of water are removed by an electrical method.

In addition, the steel sheet passed through the electrolytic cleaning tank 120 is passed to the drying chamber 150 to remove the foreign matter remaining on the surface of the steel sheet while passing through the transverse tank 140 containing the transverse solution, and then dry the surface of the steel sheet as hot air while A scrubber for scrubbing the upper and lower surfaces of the steel sheet as a plurality of brushes 131a and 132a between the alkaline cleaning tank 110 and the electrolytic cleaning tank 120 and between the electrolytic cleaning tank 120 and the transverse tank 140. 131 and 132 are disposed respectively.

On the other hand, the cleaning liquid used in the alkaline cleaning tank 110, the electrolytic cleaning tank 120 of the cleaning line as described above, as shown in Figure 1 (b), the cleaning liquid is the tank 110 ( The cleaning liquid is discharged to the circulating storage tank 111 through the discharge pipe 115 of 120, and the cleaning liquid stabilized by debris from the circulating storage tank 111 is circulated through the circulation pump 112 and the supply pipe 114. Bar 110 is re-supplied to 120, the supply pipe 114 is provided with a steam heat exchanger 113 for maintaining the proper temperature of the circulating supplied cleaning liquid in the resupply process for cleaning the steel sheet.

However, a large amount of bubbles are generated by saponification of the rolling oil, which is a foreign substance on the surface of the steel plate in the alkaline cleaning and electrolytic cleaning process, in the process of discharging the cleaning liquid into the circulation storage tank 111 and recycling the bubbles. Overflowing storage tank 111 is discharged to the outside through the overflow pipe 116, which acted as a main cause of polluting the surrounding equipment and water quality.

Accordingly, the most widely used method for removing bubbles generated in the cold rolling process is to suppress foam generation by adding a defoaming agent in a cleaning liquid at a constant concentration.

However, in the process of cleaning cold rolled products of steel mills, since the consumption of the cleaning liquid is very large and the characteristics of the rolled oil vary greatly depending on the production conditions of the steel sheet products, the cold rolled steel sheets are washed and commercialized at high speed. The conventional method of removing and suppressing an alkali foam by adding an antifoaming agent to (111) is not only difficult to select an appropriate antifoaming agent, but also has a large cost burden due to the need for continuous feeding.

These bubbles are defined as a type of colloidal state in which individual air bubbles are dispersed in a liquid phase, and are closely related to our lives, and thus, they have been raised as problems in paper dyeing and wastewater treatment. to be.

Therefore, mechanical defoamers have been proposed, mainly from Japanese steel companies.

That is, Fig. 2 (a) is a block diagram showing a defoaming apparatus using a conventional heat source, which is a defoaming method and defoaming apparatus of the metal strip degreasing apparatus of Japanese Patent Laid-Open No. 7-286291 (1995.10.31), the steel sheet is immersed Spiral pipes 117a and 117b to which a heating medium or a cooling medium are supplied are installed in a vertical alkaline washing tank 110 and an upper bubble layer of a circulating storage tank 111 through which the cleaning liquid is circulated, and the spiral pipe 117a is provided. By having the blower 119 connected to the supply line 118 which has 117b, foaming in the upper surface of the washing | cleaning liquid was suppressed.

In addition, Figure 2 (b) is a block diagram showing a defoaming apparatus having a conventional blast chamber, which is a defoaming apparatus of the coarse cleaning liquid of Japanese Patent Laid-Open No. 9-268393 (1997.10.14), the circulation storage tank 111 Continuously installed separate blast chambers (160a, 160b) for removing bubbles at the end of the overflow pipe 116, the bubbles generated in the outside to the outside, and the blast chambers (160a, 160b) of the Installing the blasting wire mesh 161 in each of the four stages in each interior space, and the foam suction blower 112 is installed at the rear end, and a method of blasting through the wire mesh while inhaling the generated foam was proposed. The remaining bubbles not blasted in the final wire mesh of the wire mesh 161 were removed by the spray line 162 installed in the rear blast chamber 160b to spray the antifoaming agent.

And, as disclosed in Japanese Patent Laid-Open No. 9-131502 (1997.5.20), a defoaming apparatus that detonates bubbles by rotating a rotating disk blade with a motor has also been proposed.

However, when the conventional defoaming apparatus and method as described above are employed and applied to the steel mill cold rolled product production process, there are various technical problems.

That is, in the case of the apparatus for blasting the bubbles generated by the spiral pipes 117a and 117b for providing a high temperature heating medium and a cooling medium in the foam layer, the cleaning liquid temperature conditions of about 70 to 80 ° C It is not easy to set the heating medium that can blow bubbles at the temperature conditions, there is a problem that can cause a secondary obstacle thereby.

In addition, in the case of the device for installing the rupture wire mesh 161 in the separate blast chamber (160a, 160b), it was confirmed that there is a problem of the limitation of the blast efficiency due to the large amount of foam generated during high-speed rolling, rotating disk blade In the case of the device to blow bubbles by rotating the motor as a motor there was a problem that the removal efficiency is low by removing only the foam in contact with the blade.

Accordingly, the present invention has been proposed to solve the conventional problems as described above, the object of which is to explode the bubbles in the circulating storage tank in which the circulating cleaning solution is stored to prevent the alkaline foaming solution from overflowing to the outside It is to provide a defoaming device of the steel sheet cleaning line to reduce the consumption of the cleaning liquid, to maintain a comfortable operating environment, and to prevent the corrosion of equipment due to alkaline foam.

Figure 1 (a) is a block diagram showing a general steel sheet cleaning line,

Figure 1 (b) is a state diagram circulating using the cleaning liquid in a general steel plate cleaning line,

2 (a) is a block diagram showing a defoaming apparatus using a conventional heat source,

2 (b) is a configuration diagram showing a defoaming apparatus having a conventional blast chamber,

3 is a block diagram showing a defoaming apparatus of the steel sheet cleaning line according to the present invention,

Figure 4 shows the rupture portion employed in the defoaming apparatus of the steel sheet cleaning line according to the present invention,

a) is a configuration diagram of the rupture part

b) is the operational state of the blasting part.

Explanation of symbols on the main parts of the drawings

10 ...... Main Unit 11 ..... Parcel Tank

12 ...... Level sensor 13 ..... Heater element

20 ...... first blast section 21 ..... blast chamber

22 ..... blast wings 23 ..... motor member

30 ..... 2nd blast part 31 ..... Injection nozzle

40 ..... Controller 50 ..... Blur

As a technical configuration for achieving the above object, the present invention,

Alkaline cleaning tank filled with a certain amount of cleaning liquid, an electrolytic cleaning tank, a transverse tank in which the transverse liquid is stored, a brush scrubber disposed between the tanks, and a circulating storage tank for circulating the cleaning liquid used in the tank. In the method of removing the contaminants attached, and remove the bubbles generated in the circulation storage tank,

Introducing the foam of the circulation storage tank into the defoaming tank having an internal space of a predetermined size together with a cleaning liquid;

Firstly blasting the bubbles forced into the blast chamber by rotationally driving the blast blades installed in the blast chamber by the motor member of the blast chamber having a suction port formed on the lower surface corresponding to the surface of the defoaming tank;

Removing the bubbles induced in the rear end side by the suction force of the suction blower installed at the rear end of the defoaming tank through the porous plate installed at least one perpendicularly to the rear end of the defoaming tank;

And circulating and supplying the cleaning liquid from which bubbles are removed in the defoaming tank into the circulation storage tank by a circulation pump.

In addition, the present invention,

Alkaline cleaning tank filled with a certain amount of cleaning liquid, an electrolytic cleaning tank, a transverse tank filled with the transverse liquid, a brush scrubber disposed between the tank and a circulating storage tank for circulating the cleaning liquid used in the tank, on the surface of the steel plate that proceeds in one direction An apparatus for removing adhered contaminants and removing bubbles generated in the circulation storage tank,

A main body connected to the circulation storage tank through a communication tube and having a defoaming tank having an internal space of a predetermined size so as to introduce bubbles together with the cleaning liquid of the circulation storage tank;

A blast chamber having a suction port on a lower surface corresponding to the water surface of the defoaming tank; and a motor member for rotating and driving the blast blades installed in the blast chamber to suck and blow the foam forced into the blast chamber, and to blow the blast chamber. A first wave width portion for discharging the cleaning liquid converted into water droplets through the discharge port of the yarn;

A suction blower is installed to communicate with the upper layer of the defoaming tank so as to form a negative pressure. The lower end is disposed so as to be spaced apart from the bottom surface of the defoaming tank by a second blast portion for removing the bubbles induced to the rear end by the suction force of the suction blower;

The measurement value of the level sensor for detecting the level of the cleaning liquid filled in the defoaming tank is received, the measurement value of the thermometer for measuring the temperature of the cleaning liquid of the defoaming tank is received, the circulation pump for supplying the cleaning liquid into the circulation storage tank By providing a defoaming device of the steel sheet cleaning line, characterized in that it comprises a controller for controlling the operation.

Hereinafter, the present invention will be described in more detail.

Figure 3 is a block diagram showing a defoaming apparatus of the steel sheet cleaning line according to the present invention, Figure 4 (a) (b) is a block diagram showing a blast portion employed in the defoaming apparatus of the steel sheet cleaning line according to the present invention.

The apparatus 1 of the present invention, as shown in Figures 3 and 4, the foam in the circulation storage tank 111 in which the cleaning liquid is temporarily stored to circulate the cleaning liquid of the alkaline cleaning tank 110 and the electrolytic cleaning tank 120. By being installed in communication with the circulation storage tank 111 to remove all without overflowing to the outside, such a device (1) is the main body portion 10, the first wave portion 20, the second wave width The unit 30 and the controller 40 and the like.

That is, the main body portion 10 into which the cleaning liquid is introduced in addition to the bubbles generated on the water surface of the circulation storage tank 111 is provided with a defoaming tank 11 having an internal space of a predetermined size, and the defoaming tank 11 Is communicated via a communication tube (11a) is connected to one end of the upper surface and one end of the circulation storage tank 111, the communication member (11a) is installed valve member (11b) to control the flow of the cleaning liquid containing foam do.

In addition, the defoaming tank 11 is provided with a level sensor 12 for measuring the level of the cleaning liquid to be filled in at any time to transmit the level value measured by the controller 40, the lower surface of the defoaming tank 11 The heater member for measuring the temperature of the cleaning liquid to be filled at this time and transmits the temperature value measured by the controller 40, while providing a heat source when the temperature of the cleaning liquid is lower than a predetermined temperature ( 13) equipped and configured. At this time, the drain valve 14 may be provided on the lower surface of the defoaming tank 11 so as to discharge the foreign matter deposited on the tank bottom surface to the outside.

In addition, the first blasting portion 20 for blasting only the bubbles introduced into the blast chamber 21 and converting them into water droplets is discharged to a predetermined size on the lower surface corresponding to the water surface of the defoaming tank 11. A blast chamber 21 having a suction port 21a extending a predetermined length to the lower portion, and the blast chamber 21 generates a suction force at the end of the suction port 21a, through which the foam on the surface of the defoaming tank 11 In order to forcibly suck the bay, it is equipped with the blast-blade 22 which rotates in one direction by the rotational driving force of the motor member 23, and is comprised.

In addition, the cleaning liquid in which the bubble expelled by the impingement of the bubble forcedly sucked into the blast chamber 21 through the suction port 21a and the blast blade 22 through the suction port 21a is converted into water droplets on the outer surface of the blast chamber 21. A plurality of outlets 21b for discharging the gas into the defoaming tank 11 are formed.

Here, the blade 22 is preferably provided in a rectangular plate shape so as to expand the contact area with the bubble to improve the bubble rupture rate.

In addition, the blast chamber 21 is provided in the accommodating part 20a that is formed at a predetermined depth on the upper surface of the tank 11 so as to reduce the distance between the surface of the cleaning liquid filled in the defoaming tank 11 and the suction port 21a. Is disposed, one side of the outer surface of the defoaming tank 11 may be connected to the blower 50 to form a negative pressure on the upper layer of the defoaming tank (11).

In addition, the second blasting portion 30 for secondarily removing the bubbles that could not be removed by the first blasting portion 20 may not be blown by the blast chamber 21 at the rear end of the defoaming tank 11. At least one or more perforated plates 36a and 36b having a plurality of holes of a predetermined size are vertically installed to remove bubbles.

Here, the upper ends of the porous plates 36a and 36b are integrally connected to the upper surface of the defoaming tank 11 so that unexploded bubbles do not overflow in the defoaming tank 11, and the lower end is a cleaning liquid. It is arranged to be spaced apart a certain height from the bottom surface of the parcel tank 11 to enable a smooth flow of.

Meanwhile, a plurality of antifoams are injected into the second blasting portion 30 so as to completely remove the unexploded bubbles as the antifoam while passing through the porous plates 32a and 32b disposed at the rear end of the antifoam tank 11. A spray line 32 having two spray nozzles 31 and equipped with the spray nozzle 31 at an end thereof is connected to an antifoam storage tank 33 in which a predetermined amount of antifoam is stored, and the antifoaming agent is provided in the spray line 32. The control valve 35a and the supply pump 35 are provided so that the defoaming agent of the storage tank 33 may be supplied smoothly.

Then, the controller 40 receives the level measurement value measured from the level sensor 12 and controls the operation of the motor member 21 based on this to force the suction of bubbles into the blast chamber 21. It controls the operation, and receives the temperature measurement value measured by the thermometer (13a) and controls the operation of the heater member 13 for providing a heat source to the defoaming tank 11 cleaning liquid based on this.

In addition, the controller 40 controls the operation of the supply pump 35 and the control valve 35a for supplying the defoaming agent in the defoaming agent storage tank 33 to the injection line 32, and the defoaming tank 11 Controlling the operation of the circulation pump 19 of the circulation pipe 19a for recirculating and supplying only the cleaning liquid from which bubbles are removed in the circulation storage tank 111.

In the case of removing bubbles using the apparatus of the present invention, first, a large amount of foam is provided on the upper surface of the cleaning liquid supplied into the alkaline cleaning tank 110 and the electrolytic cleaning tank 120 to remove contaminants attached to the steel sheet. The bubbles generated to greatly reduce the cleaning efficiency are supplied from the tanks 110 and 120 to the circulation storage tank 111 through the discharge pipe 115. In this process, a large amount of foam is formed on the water surface of the tank 111. Is generated, and the generated bubbles overflow into the defoaming tank (11) through the communication pipe (11a) provided between the tank (111) and the defoaming tank (11).

Accordingly, bubbles in the circulation storage tank 111 are continuously discharged into the defoaming tank 11 through the communication pipe 11a, which is a bubble discharge pipe, and a certain amount of cleaning liquid is also discharged to the defoaming tank 11. In addition, the amount of the cleaning amount introduced into the defoaming tank 11 together with the foam is controlled by the valve member 11b installed in the communication pipe 11a.

At this time, when the water level in the defoaming tank 11 reaches a position suitable for forcing the bubble into the blast chamber 21, the controller 40 rotates the blast blade 22 mounted in the blast chamber 21. By applying an external power source to the motor member 23 to drive the blade 22 in one direction, a suction force is generated in the blast chamber 21.

Subsequently, bubbles on the front surface of the surface of the defoaming tank 11 are introduced into the explosion chamber 21 through the suction port 21a corresponding to the surface of the defoaming tank 11 by the suction force generated in the explosion chamber 21. Forced suction, the bubble is forcedly blown by bursting and hitting the rotating portion of the blade 22 is converted into water droplets, the discharged through the formed water droplets penetrated through the outer surface of the blast chamber 21 by centrifugal force ( Externally discharged through 21b) and resupply into the parcel tank 11.

In addition, the fine bubbles, which are the rupture residues that are not ruptured primarily in the blast chamber 21 disposed at the front end of the defoaming tank 11, are provided with two-stage porous plates 36a installed at the rear end of the defoaming tank 11. It is exploded and removed while continuously passing through the holes of 36b.

In addition, the cleaning liquid in the defoaming tank (11) is always maintained at a constant temperature by the thermometer (13a) and the heater member 13 for recirculation use, the cleaning liquid in which the foam is removed in the defoaming tank (11) is transferred to the cleaning liquid The circulation pump 19 is re-supplied to the circulation storage tank 111 through the circulation pipe (19a).

On the other hand, in the abnormal operating conditions in which the production of the cold rolled steel sheet is made at a very high speed or a large amount of bubbles are generated according to the cleaning liquid forming conditions, the second foam detecting sensor installed near the porous plates 36a and 36b ( 42 is detected by the bubbles generated above a certain level, and when the detection signal of the second bubble detection sensor 42 is transmitted to the controller 40, the defoamer of the defoamer storage tank 33 in the controller 40 The feed pump 35 is operated to supply the gas into the defoaming tank 11 through the spray nozzle 31 of the spray line 32.

In addition, the circulation storage tank 111 is also provided with a first bubble detecting sensor 41 for detecting the occurrence of bubbles to control the operation of the motor member 23, respectively, the first bubble detecting sensor 41 is Installed in the circulation storage tank 111 is to detect the degree of foam generated in the interior space.

These sensors were used with a model 14LRF level switch from Great Lakes Instruments of the United States.

(Example)

In this embodiment, the solution used for the alkaline cleaning operation of the cold-rolled cleaning process is caustic soda (NaOH), and the alkaline solution is usually made at a concentration of 2 to 5% and used as a cleaning solution for each operating condition of cold rolled steel sheet manufacturing. Looking at the properties of the cleaning solution due to the contaminants on the cold rolled steel sheet measured in this embodiment as shown in Table 1 below, the generation of bubbles due to the saponification action containing a large amount of tallow.

Alkaline Cleaning Tank Cleaning Liquid Cleaning solution of electrolytic cleaning tank pH 13.6 14 SS 4220 ppm 810 ppm Turbidity 12.4 NTU 6.3 NTU oil 514ppm 14 ppm Surface tension 29.7 dyne / cm (70C) 30.8dyne / cm (80C) Electrical conductivity 79.6mS / cm 174.6mS / cm COD 930 ppm 300 ppm Temperature 70-80 70 ~ 80 ℃

Bubbles excessively discharged by the cleaning liquid circulated into the circulation storage tank 111 from the tanks 110 and 120 are collected into the defoaming tank 11 through the communication pipe 11a, and the blast width of the defoaming tank 11 is increased. The bubbles are forced into the chamber 21 and at the same time, the bubbles 22 are blown primarily by the vanes 22 installed therein, and the micro bubbles that have not been removed from the chamber 21 are secondarily formed by the second porous plate. The rinsing solution, which is blasted while passing, and the bubbles are removed, is supplied to the circulation storage tank 111 to be reused.

Here, the interval H between the water surface of the defoaming tank 11 and the suction port 21a is constantly maintained at 30 to 70 mm, and the horsepower of the motor member 23 is 0.4 kw, and the rotation speed is 3000 to 3600 rpm. It was confirmed that the most appropriate rupture occurred in the range.

In addition, as a result of examining the blasting characteristics of the porous plates 36a and 36b, when the porous plate having the through holes of 12 mm, 10 mm, 6 mm, and 3 mm was installed in the defoaming tank 11 and the wave behavior was examined, In the case of the perforated plate and the perforated plate of 10 mm, the rupture was about 60%, but a considerable amount of bubbles remained in the defoaming tank 11.

However, when the 6mm, 3mm perforated plate was installed in duplicate, it was confirmed that the bubbles in the primary network were finely blasted, and this was completely blown through the secondary network.

Therefore, as described above, the bubble forcedly sucked by the centrifugal force is first removed in the blast chamber 21, and the bubble is secondarily formed in the porous plates 36a and 36b through which 6 mm and 3 mm through holes are formed. As a result, the rear upper layer of the defoaming tank 11 is subjected to a negative pressure as a blower 50, and as a result, a large amount of bubbles formed in the upper portion of the cleaning liquid on the circulation storage tank 111 is smoothly transferred into the defoaming tank 11 And, the blasting while passing through the blast chamber (21), the residual air bubbles were confirmed to disappear by continuously passing through the 6mm porous plate and the 3mm porous plate, the cleaning liquid of the bubble is removed, the circulation pump for transport (19) By the it was confirmed that the transfer to the circulation storage tank (11).

According to the present invention as described above, the bubble generated in the circulation storage tank is forced into the blast chamber of the defoaming tank and at the same time, the foam is blown as the blast blades installed in the blast chamber to remove the foam first, and the remaining foam is the rear end. By removing the secondary by the porous plate installed in the, it is possible to prevent the contamination of the surrounding environment by the alkaline bubbles discharged from the outside in the circulation storage tank and to corrode the surrounding equipment.

In addition, it is possible to reduce the equipment maintenance cost by reducing the consumption of the cleaning liquid circulated in the steel plate cleaning line, and the effect of improving the cleaning efficiency in the cleaning line can be obtained by ensuring the circulating use of the clean cleaning liquid.

While the invention has been shown and described with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit or scope of the invention as set forth in the claims below. I would like to clarify that knowledge is easy to know.

Claims (10)

delete delete delete delete A brush scrubber 131 disposed between an alkaline cleaning tank 110 and an electrolytic cleaning tank 120 filled with a predetermined amount of washing liquid, a transverse tank 140 filled with a transverse liquid, and the tank 110, 120, 140. 132 and the circulating storage tank 111 for circulating the washing liquid used in the tank 110, 120 to remove contaminants attached to the steel plate surface in one direction, and generated in the circulating storage tank 111 In the device for removing bubbles, The main body portion which is connected to the circulation storage tank 111 and the communication tube (11a), and equipped with a defoaming tank (11) having an internal space of a predetermined size, together with the cleaning liquid of the circulation storage tank (111), the foam flows into the inside 10; A motor member 23 having a blast chamber 21 having a suction port 21a on the lower surface corresponding to the water surface of the defoaming tank 11 and rotating the blast blade 22 installed in the blast chamber 21. A first blasting portion 20 for sucking and blowing the foam forced into the blasting chamber 21 and discharging the washing liquid converted into water droplets through the outlet 21b of the blasting chamber 21; The suction blower 50 is installed in communication with the upper layer of the defoaming tank 11 so as to form a negative pressure, and at least one or more vertically perforated plates 36a and 36b are provided at the rear end of the defoaming tank 11, and the c. The upper end of the plate (36a, 36b) is integrally connected to the upper surface of the parcel tank 11, the lower end is arranged to be spaced apart from the bottom surface of the parcel tank 11 by the suction blower ( A second wave section 30 for removing bubbles induced to the rear end side by the suction force of 50); The measurement value of the level sensor 12 for detecting the level of the washing liquid filled in the defoaming tank 11 is received, the measured value of the thermometer 13a for measuring the washing liquid temperature of the defoaming tank 11 is received, Defoaming device of the steel sheet cleaning line, characterized in that it comprises a controller (40) for controlling the operation of the circulation pump (19) for supplying the washing liquid into the circulation storage tank (111). 6. The second wave section (30) is provided with an injection line (32) equipped with a plurality of injection nozzles (31) for discharging the antifoaming agent directly below the porous plates (36a, 36b). The spray line 32 is connected to an antifoam storage tank 33 in which a predetermined amount of antifoam is stored, and the control valve 35a and the antifoam of the antifoam storage tank 33 are smoothly supplied to the spray line 32. A defoaming device for a steel plate cleaning line, characterized in that the supply pump (35) is configured to connect. The second foam for controlling the supply of the antifoaming agent to the injection nozzle 31 by detecting the generation of bubbles above a certain level in the vicinity of the porous plates 36a and 36b at the rear end of the defoaming tank 11. A defoaming device for a steel sheet cleaning line, characterized in that the sensor 42 for sensing. The method of claim 5, wherein the blast chamber 21 is contained in the upper surface of the defoaming tank 11 so as to adjust the interval (H) between the cleaning liquid surface filled in the defoaming tank 11 and the suction port (21a). The defoaming apparatus of the steel plate cleaning line, characterized in that disposed in the receiving portion (20a). The steel sheet cleaning according to claim 5, wherein the circulation storage tank (111) is provided with a first bubble detecting sensor (41) for detecting the occurrence of bubbles and controlling the operation of the motor member (23). Defoamer of the line. delete