KR100723120B1 - Apparatus for alkali foam removal in strip cleaning process and its method - Google Patents

Abstract

The present invention provides an alkali foam removing device and a method of cleaning a steel plate using a liquid solution of the alkaline solution foam and recirculating without external discharge.

The present invention is a defoaming tank unit connected to the alkaline solution tank via a connecting pipe to receive the alkali bubbles therein; A blasting unit provided inside the defoaming tank unit for converting the alkali foam into an alkaline solution by centrifugal force; An alkaline solution temporary storage tank connected to the defoaming tank unit through an overflow pipe to temporarily store an alkaline solution obtained from foam; A transfer unit for returning the alkaline solution from the alkaline solution temporary storage tank to the alkaline solution tank; And a control unit for driving the blasting unit according to the bubble level of the defoaming tank unit and automatically controlling the alkali solution from the alkaline solution temporary storage tank to the alkali solution tank according to the level of the alkaline solution temporary storage tank. It provides an alkali defoamer of steel sheet cleaning line.

According to the present invention, it is possible to efficiently remove alkali bubbles, condense and convert them into an alkali solution, and recover the entire amount thereof to obtain an effect of reuse.

Alkaline solution, foam, steel plate cleaning line, alkali defoamer, defoaming tank part

Description

Apparatus for Alkali Foam Removal in Strip Cleaning Process and Its Method}

1 a) is a process chart showing a steel plate cleaning line according to the prior art,

        b) is a process structural diagram showing a structure in which the cleaning solution is circulated and used according to the conventional art.

2 is a structural diagram showing a defoaming apparatus according to the prior art,

         a) a diagram using a heat source,

         b) is a block diagram with a blast chamber.

3 is a schematic diagram of a process for implementing an alkali foam removing device and a method for cleaning a steel sheet according to the present invention.

Figure 4 is a side view showing the structure of the rupture portion provided in the alkali defoamer of the steel sheet cleaning line according to the present invention.

5 is a block diagram showing the defoaming pumps of the rupture portion provided in the alkali defoamer of the steel sheet cleaning line according to the present invention,

         a) is an external side view, b) is a sectional drawing.

  <Description of the symbols for the main parts of the drawings>

1 .... Alkali foam removing device of steel sheet cleaning line according to the present invention

10 .... parcel tank part 20 .... blast part

22 .... Parcel pump 26 .... Centrifugal vanes

32 .... buffer space part 34 .... coolant supply pipe

36 .... spray nozzle 43,53 .... coolant coil

50 .... Alkaline Solution Temporary Storage Tank 53 .... Cooling Water Coil

60 .... conveying section 62 .... pneumatic conveying pump

66 .... pneumatic line 70 .... washing section

76 .... drain tube 80 .... control unit

82 .... 3-level sensor 86 .... 2-level sensor

200 .... Conventional cleaning process diagram 210 .... Alkaline cleaning tank

220 .. Electrolytic cleaning tank 221 .... Electrode

231a, 232a ... Brush 231,232 ... Scrubber

240 .... Transverse tanks 260a, 260b .... blast chamber

261 .... Wire Mesh 262 .... Spray Line

B .... Automatic Control Valve

The present invention relates to an apparatus and method for removing alkali bubbles generated in a steel sheet cleaning line, and more particularly, rolling oil, iron, and reaction attached to the surface of the steel sheet during the rolling and annealing of the steel sheet in a cold rolling line of a steel mill. It is possible to improve the cleaning effect, reduce the treatment cost, and prevent water pollution by liquefying a large amount of alkaline solution bubbles generated during the cleaning process using alkaline solution for the product stony gum (soda stearate). The present invention relates to an alkali defoamer of the steel sheet cleaning line, and a method thereof.

In general, in the cold-rolled product production line of the steel mill cold-rolled hot-rolled steel sheet, followed by hot dip galvanizing line and continuous annealing line, galvanized line and electrolytic galvanized zinc plating Line, etc.

In these processes, before the surface is treated, foreign materials such as rolled oil, hydraulic oil, and iron adhered to the surface of the steel sheet in the pickling, cold rolling, and iron powders are adhered to 100 to 200 mg / m². Treatment In the plating process, etc., it adversely affects the adhesion of the plating and the resistance of corrosion, and increases the porosity, so it is cleaned by using a high temperature alkaline solution (NaOH 1 ~ 5wt%) prior to annealing the steel sheet. Done.

In order to maximize the cleaning efficiency, the cleaning process is a combination of alkali cleaning, electrolytic cleaning, and brush cleaning.

That is, the cleaning process 200, as shown in Figure 1, Alkaline cleaning is slightly different depending on the characteristics of the cold rolling line, but the alkaline cleaning tank of 70 ~ 80 ℃ in the case of alkaline cleaning as the first cleaning step It is deposited in 210 or by cleaning by spraying the cleaning liquid on the steel plate surface.

In the case of the electrolytic cleaning, which is the second cleaning step, the steel sheet passes between the electrode devices 221 installed in the electrolytic cleaning tank 220 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 to the other electrode, which has a good durability in the conductive and alkaline solution, the rolling oil and fine iron powder strongly adhered to the surface of the steel sheet by electrolysis of water are removed in an electrical manner. .

In addition, the steel sheet passed through the electrolytic cleaning tank 220 is passed to the drying chamber 250 to remove the foreign matter remaining on the surface of the steel sheet while passing through the transverse tank 240 in which the transverse solution is contained, and then to dry the surface of the steel sheet as hot air to proceed to the drying chamber 250. On the other hand, between the alkali cleaning tank 210 and the electrolytic cleaning tank 220, between the electrolytic cleaning tank 220 and the transverse tank 240, the upper and lower surfaces of the steel sheet a plurality of brushes (231a, 232a) As scrubbers (231) (232) are each disposed.

On the other hand, the cleaning solution used in the alkaline cleaning tank 210 and the electrolytic cleaning tank 220 of the cleaning line as described above, as shown in Figure 1 (b), the cleaning liquid is the tank 210 ( The cleaning solution is discharged to the alkali solution tank 211 through the discharge pipe 215 of 220, and the cleaning solution stabilized by the foreign matter in the alkali solution tank 211 through the circulation pump 212 and the supply connection pipe 214. It is supplied to tanks 210 and 220 for reuse.

In this process, the steel sheet is provided with a steam heat exchanger 213 for maintaining an appropriate temperature of the cleaning liquid circulated to the supply connection pipe 214 in the resupply process for cleaning.

However, in the process of discharging and recycling the cleaning liquid into the circulation storage tank 211, a large amount of bubbles are generated by the saponification action of the rolled oil, which is foreign matter adhered to the steel plate surface of the alkali cleaning and electrolytic cleaning process. The foam is discharged to the outside through the overflow pipe 216 overflows the alkaline solution tank 211, which acts as a main cause of polluting the surrounding equipment and water quality.

At this time, the flow rate of the alkaline cleaning liquid recovered and introduced into the circulation storage tank 211 depends on the annealing speed, and in general, when the annealing operation is performed in excess of the annealing speed, the cleaning liquid containing an excessive amount of foam becomes an alkaline solution tank ( 211), the proper level is exceeded.

Therefore, the hot cleaning liquid containing a large amount of foam overflows through the overflow pipe 216 and is discharged to the outside.

Among the conventional methods for removing bubbles generated as described above, the most widely proposed method is to suppress foaming by adding a defoaming agent in a predetermined concentration.

However, in the process of cleaning cold rolled products of steel mills, since the consumption of the cleaning liquid is very large due to washing and commercializing the cold rolled steel sheets at high speed, and the characteristics of the rolling oil also vary greatly depending on the steel sheet product production conditions, the circulation storage tank The conventional method of removing and suppressing the alkali foam by adding an antifoaming agent into the (211) is not only difficult to select an appropriate antifoaming agent but also has a large cost burden depending on the need for continuous feeding.

Therefore, mechanical defoaming apparatuses to improve this have been conventionally proposed. That is, Fig. 2 (a) is a block diagram showing a conventional defoaming apparatus using a heat source, which is a "defoaming method and defoaming apparatus of a metal strip degreasing apparatus" of Japanese Patent Laid-Open No. 7-286291 published on October 31, 1995, Spiral pipes 217a and 217b are installed as a heating medium or a cooling medium in the upper bubble layer of the vertical alkaline cleaning tank 210 in which the steel plate is immersed and the alkaline solution tank 211 in which the cleaning liquid is circulated. By having the blower 219 connected to the supply line 218 having 217a) and 217b, it was possible to suppress foaming on the upper surface of the cleaning liquid.

FIG. 2 (b) is a block diagram showing a defoaming apparatus having a conventional blast chamber, which is a defoaming apparatus for a strong cleaning solution of Japanese Patent Laid-Open No. 9-268393 published on October 14, 1997, in the alkaline solution tank. A separate blast chamber 260a, 260b for continuous bubble removal is installed in series at the end of the overflow pipe 216 where the generated bubbles are discharged to the outside, and a bubble suction blower 212 is provided at the rear end thereof. It is proposed to install and blow through the wire mesh 261 while sucking the bubbles generated in the blast chamber (260a, 260b).

In addition, this conventional technique is to spray and remove the antifoaming agent by the spray line 262 is installed in the trailing blast chamber 260b for the remaining bubbles not ruptured in the final wire mesh in the wire mesh 261.

As another conventional technique, as described in Japanese Patent Application Laid-open No. Hei 9-131502 with a letter of May 20, 1997, a defoaming device for detonating 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 a steel mill cold rolled product production process, there are various technical problems.

That is, in the conventional defoaming apparatus having a spiral pipe (217a, 217b) for providing a high temperature heating medium and a cooling medium in the foam layer, the apparatus that blows bubbles, the cleaning liquid temperature conditions for the best cleaning efficiency is about 70 ~ 80 It is not easy to set a heating medium that can blow bubbles at a temperature of ℃. Therefore, there is a problem that can cause secondary failures thereby.

In addition, in the case of the apparatus for installing the rupture wire mesh 261 in the separate blast chambers (260a, 260b), a problem with the limitation of the blast efficiency due to the large amount of foam generated during high-speed rolling was confirmed, the rotating disk blade In the case of blowing bubbles by rotating the motor as a motor, only the bubbles contacting the blades were removed, thereby causing a problem of low removal efficiency.

Therefore, in order to improve these problems, Korean Patent No. 10-0471600 receives a large amount of bubbles discharged to the outside by overflowing from the alkaline solution tank 211 that maintains a high temperature as a separate defoaming tank and blasts through a centrifugal force blasting part. It has been limited to a device that can be liquefied and supplied and recycled to the alkaline solution tank (211).

However, the amount of the alkaline cleaning liquid containing a large amount of foam recovered and introduced into the alkali solution tank 211 depends on the annealing rate of the steel sheet, and when the annealing operation is performed in excess of the annealing rate, an excessive amount of excess As the cleaning solution containing the foam is recovered to the alkali solution tank 211, the proper level of the alkali solution tank 211 is exceeded.

Therefore, when a high temperature cleaning liquid containing a large amount of foam is supplied to a defoaming tank equipped with a centrifugal force blasting device through a foam discharge connector and the foam is to be removed and recovered, excess solution of the abnormal operation supplied with foam is supplied. As a result, it is supplied above the level of the rupture solution, which is a proper operating condition of the centrifugal force blasting device, and thus causes a problem in the operation of the centrifugal force blasting part.

In order to solve this problem, the conventional centrifugal force blasting apparatus has a problem of adjusting the bubble inlet level, and at the same time, the instability of the water level on the alkaline solution tank basically causes the instability of the cleaning chemical concentration in the alkaline cleaning operation, As a result, the lowering of the cleaning efficiency increases the defect rate of the product and causes complex problems in the process.

Therefore, the present invention has been proposed to solve the conventional problems as described above, the object of which is that the excess foam and solution flows into the alkaline solution tank in accordance with the increase or decrease of the annealing rate, the alkaline foam solution is discharged overflow to the outside In this case, the present invention provides an alkali foam removing device and method for cleaning a steel sheet, which can stably blow bubbles to recover a solution, thereby reducing external discharge of the cleaning liquid and maintaining a comfortable operating environment.

Another object of the present invention is to provide an apparatus and method for removing alkali foam in a steel sheet cleaning line, which can prevent external corrosion of the cleaning liquid to prevent facility corrosion due to alkaline foam and improve the durability by protecting the equipment. .

The present invention as a technical configuration for achieving the above object, in the apparatus for removing alkali bubbles generated in the steel sheet cleaning line,

A defoaming tank part connected to the alkaline solution tank through a connecting pipe to receive alkali foam therein;

A blasting unit provided inside the defoaming tank unit for converting the alkali foam into an alkaline solution by centrifugal force;

An alkaline solution temporary storage tank connected to the defoaming tank unit through an overflow pipe to temporarily store an alkaline solution obtained from foam;

A transfer unit for returning the alkaline solution from the alkaline solution temporary storage tank to the alkaline solution tank; And

And a control unit for driving the blasting unit according to the bubble level of the defoaming tank unit and automatically controlling the alkali solution from the alkaline solution temporary storage tank to the alkali solution tank according to the level of the alkaline solution temporary storage tank. It provides an alkali defoamer of the steel plate cleaning line characterized in that.

And the present invention is preferably the defoaming tank unit to increase the rupture throughput according to the amount of foam when a large amount of foam and a solution is instantaneously supplied therein, and in conjunction with the defoaming tank so that the solution level does not increase above a certain level It provides an alkali foam removing device of the steel sheet cleaning line, characterized in that it further comprises a buffer space portion to secure a free space on one side of the part.

In addition, the present invention is a method for removing alkali bubbles generated in the steel sheet cleaning line,

Introducing bubbles of the alkali solution tank into the defoaming tank section having a predetermined internal space;

Detonating and converting the alkali bubbles in the defoaming tank into an alkali solution so as to remove the bubbles introduced into the defoaming tank;

Moving the alkaline solution from the defoaming tank part to an alkaline solution temporary storage tank when the alkali solution reaches a predetermined level;

Cooling the alkali solution in the defoaming tank portion and the alkaline solution temporary storage tank to stabilize foaming of the solution; And

It provides a method for removing alkali bubbles of the steel sheet cleaning line, comprising the step of: returning the alkaline solution in the alkaline solution temporary storage tank back to the alkaline solution tank.

And the present invention preferably further comprises the step of temporarily storing a large amount of foam and solution in the free space of the buffer space in accordance with the abnormal cleaning operation of the steel sheet to the defoaming tank unit further comprises the step of storing Provides a method for removing alkaline bubbles in lines.

In addition, the present invention preferably further comprises the step of adjusting the bubble removal rate in the defoaming tank portion by controlling the operation of the blast portion in accordance with the foam solution level of the defoaming tank portion, alkaline foam removing method of the steel sheet cleaning line. To provide.

And the present invention preferably further comprises the step of blasting the foam in the buffer space by spraying the coolant by automatically detecting the excess state when the foam is excessively introduced into the buffer space portion from the defoaming tank portion It provides a method for removing alkali bubbles in the cleaning line.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

3 is a block diagram showing an overall alkali foam removing device 1 of the steel sheet cleaning line according to the present invention.

Alkaline defoaming device (1) of the steel sheet cleaning line according to the present invention, as shown in Figure 3, alkali to receive the bubbles of the alkaline cleaning tank 210 and the electrolytic cleaning tank 220 to store without overflowing to the outside The defoaming tank part 10 provided in communication with the solution tank 211 is provided.

That is, the defoaming tank part 10 into which the bubbles generated on the water surface of the alkali solution tank 211 flows into the interior through the connecting pipe 12 has a defoaming tank having a predetermined internal space.

And the defoaming tank part 10 has a blast part 20 for converting the alkali foam into an alkaline solution by centrifugal force therein, the blast part 20 is the upper side of the defoaming tank part 10 Centrally located, there are a number of defoaming pumps 22.

The blast part 20 has a partition wall part 24 in which defoaming pumps 22, preferably three defoaming pumps 22 are arranged, as shown in FIGS. 4 and 5, wherein the partition part The defoaming pumps 22 which consist of centrifugal pumps are arrange | positioned inside 24.

The defoaming pumps 22 of the blasting portion 20 each have centrifugal vanes 26 built therein, and a suction port 29a is formed at the center of the casing 28 where the centrifugal vanes 26 rotate, and the casing ( A discharge port 29b is formed on the outer circumferential side of 28. When the defoaming pumps 22 operate, suction force is generated at the inlet port 29a in the center of the centrifugal blade 26 to suck the internal foam of the defoaming tank unit 10. , While being discharged in a condensed state into the alkaline solution through the outlet 29b while passing through the centrifugal blade 26.

Preferably, the three defoaming pumps 22 of the blast part 20 are mounted to the defoaming tank part 10, and the two defoaming pumps 22 operate according to the foam level of the defoaming tank part 10. Alternatively, three units are operated, and this operation setting is made through the controller 80 to be described later.

And the alkali foam removing device 1 of the steel sheet cleaning line according to the present invention, when the foam in the defoaming tank unit 10 is excessively supplied to one side of the defoaming tank unit 10, the buffer room is temporarily buffered and stored The buffer space part 32 which is a space is formed.

A cooling water supply pipe 34 and a spray nozzle 36 are disposed at the upper side of the buffer space part 32 to deflate the alkali bubbles by supplying the cooling water to the excess alkali bubbles introduced into the buffer space part 32. It is.

The defoaming tank section 10 also forms a plurality of, preferably three port, overflow pipes 38 at their mid-height points, the bottom surface 39 of which is inclined to one side to form the drain pipes 40. The coolant coil 43 is installed on the inclined bottom surface 39 so that the coolant circulates from the outside.

The cooling water coil 43 is for lowering the temperature of the defoaming tank unit 10. The alkali foam and the alkali solutions are typically maintained at 70 to 80 ° C., but at higher temperatures, the alkaline foam is released from the alkali solution. More actively generated.

Therefore, the temperature of the alkali solution is lowered to an appropriate temperature in order to prevent the further generation of such alkaline bubbles, and the temperature of the cooling water circulated through the cooling water coil 43 is about 20 ° C.

And the alkali foam removing device 1 of the steel sheet cleaning line according to the present invention is provided with an alkaline solution temporary storage tank 50 is connected through the overflow pipe 38 to temporarily store the alkali solution obtained from the foam.

The alkaline solution temporary storage tank 50 is composed of a tank having an internal space of a predetermined size, and receives the alkaline solution through the overflow pipe 38 in the defoaming tank part 10.

The alkaline solution temporary storage tank 50 has a cooling water coil (not shown) at the bottom thereof, and lowers the temperature of the alkali solution contained therein to an appropriate temperature to prevent generation of alkali bubbles.

The present invention also includes a transfer unit 60 for returning the alkaline solution from the alkaline solution temporary storage tank 50 to the alkaline solution tank 211.

The transfer unit 60 is provided with a plurality of pneumatic transfer pumps 62, mounted on a pipe 64 connecting the alkaline solution tank 211 from the alkaline solution temporary storage tank 50, pneumatic Line 66 may be connected to achieve opening and closing of the operation.

When the pneumatic transfer pumps 62 are operated, the transfer unit 60 supplies an alkali solution from the alkaline solution temporary storage tank 50 to the alkali solution tank 211.

In addition, the transfer unit 60 further includes a cleaning unit 70 for preventing the blockage of the pipes of the pneumatic transfer pump 62.

The washing unit 70 is such that the temperature of the alkaline solution in the pneumatic transfer pump 62 and the transfer pipe 64 is lowered while the pneumatic transfer pumps 62 transfer the alkaline solution and then wait for the next operation. When the alkaline solution is deposited, the pneumatic transfer pump 62 and the transfer pipe 64 may be blocked.

Therefore, in order to prevent this, after the operation of the pneumatic conveying pump 62, the washing water is supplied to the pneumatic conveying pump 62 and the conveying pipe 64 to automatically clean the inside thereof. The cooling water pipe 72 and the valve B are connected to the inlet pipe 62a, and a drain pipe 76 is formed at the outlet side of the transfer pump 62.

And the alkali foam removal device 1 of the steel sheet cleaning line according to the present invention drives the rupture unit 20 according to the foam level of the defoaming tank unit 10, the level of the alkaline solution temporary storage tank 50 In accordance with the control solution 80 for automatically transferring the alkali solution from the alkaline solution temporary storage tank 50 to the alkali solution tank 211.

The control unit 80 is made of a field facility control computer or a PLC (Programmable Logic Controller), and automatically controls the alkali foam removing device 1 of the steel sheet cleaning line according to the present invention according to a preset program.

The control unit 80 is provided with a three-stage level sensor 82 inside the defoaming tank unit 10 to drive the blasting unit 20 according to the foam level of the defoaming tank unit 10. It is connected to the three-stage level sensor 82 to automatically control the defoaming pumps 22 of the blast part 20.

That is, when the level of the alkali solution in the defoaming tank part 10 is detected by the lowest detection part 84a of the said three level sensor 82, only two of the said three defoaming pumps 22 are operated.

That is, when the level of the alkaline solution is detected in the lowermost detection section 84a, this means that there is not much alkali solution in the defoaming tank section 10, so that the amount of foam to be removed is relatively small, so that the two defoaming pumps 22 Operate.

However, when the alkali solution is detected in the intermediate laurel detection unit 84b, the intermediate level detection unit 84b corresponds to the level of the overflow tube 38 of the defoaming tank unit 10 so that the alkali solution is in the defoaming tank unit 10. Since it means that the alkaline solution to the temporary storage tank (50) side, it is determined that the considerable amount is located inside the defoaming tank unit 10 to operate the three defoaming pumps 22 of the blasting unit 20.

In this case, the alkaline bubbles present in large quantities in the defoaming tank section 10 are all converted into the alkaline solution at one time by the three defoaming pumps 22.

If an alkali solution is then detected at the topmost level detection section 84c, this is the movement of the alkali solution from the defoaming tank section 10 toward the alkaline solution temporary storage tank 50, while at the same time the buffer space section 32 Foam enters the side, and it is determined that the alkali solution level in the defoaming tank part 10 has reached a dangerous level.

When the uppermost level is reached, a risk level may also affect the operation of the defoaming pump 22. In such a case, the emergency overflow pipe 38 is opened to emergency discharge of the alkaline solution to the outside, and a separate storage tank is provided. Store the alkali solution in (not shown). At the same time, from the cooling water nozzle 36 provided in the buffer space portion 32, the cooling water is injected into the buffer space portion 32 to remove excess alkali bubbles.

In this way, the controller 80 discharges the alkali solution appropriately according to the alkali solution level of the defoaming tank unit 10.

In addition, the controller 80 automatically controls to transfer the alkaline solution from the alkali solution temporary storage tank 50 to the alkali solution tank 211 according to the level of the alkaline solution temporary storage tank 50.

To this end, the controller 80 includes a two-stage level sensor 86 for detecting the level of the alkaline solution temporary storage tank 50. The second level sensor 86 is connected to the solution transfer pump 62 through the control unit 80, and the solution level in the alkaline solution temporary storage tank 50 is detected by the high level detection unit 88a. In this case, the transfer pump 62 is operated to transfer the alkali solution from the alkali solution temporary storage tank 50 to the alkali solution tank 211.

When the solution level of the alkaline solution temporary storage tank 50 is lowered and detected by the low level detection unit 88b, the operation of the transfer pump 62 is stopped.

Through this process, the controller 80 automatically controls the alkali solution from the alkali solution temporary storage tank 50 to be transferred to the alkali solution tank 211.

Reference numerals B are automatic control valves, which are electrically automatic valves electrically connected to the controller 80 and automatically opened and closed remotely.

Alkaline foam removing method of the steel sheet cleaning line of the present invention using the alkali foam removing device (1) of the steel sheet cleaning line according to the present invention configured as described above is as follows.

In the method for removing alkali bubbles generated in the steel sheet cleaning line according to the present invention, first, the foam of the alkali solution tank 211 is introduced into the defoaming tank part 10 having an internal space of a predetermined size.

In this process, the alkali bubbles of the alkali solution tank 211 are introduced into the defoaming tank part 10 through the connecting pipe 12.

Then, the step of detonating the alkali bubbles in the defoaming tank unit 10 to remove the bubbles introduced into the defoaming tank unit 10 is converted into an alkaline solution.

This uses centrifugal defoaming pumps 22 provided in the blasting part 20, and the defoaming pumps 22 are two defoaming pumps when the level of the alkali solution is small in the defoaming tank part 10. When the (22) are in operation and the level of the alkaline solution is high, the three defoaming pumps 22 are operated to effectively remove bubbles in the defoaming tank section 10 and to condense the alkali solution.

In addition, the present invention is made to move to the alkaline solution temporary storage tank 50 from the defoaming tank unit 10 when the alkali solution is a predetermined level.

Since the overflow tubes 38 are mounted at a constant height of the defoaming tank part 10, the alkali solution from the defoaming tank part 10 is transferred to the alkali solution temporary storage tank 50 through the overflow pipes 38. It is moved to the side.

In the above process, the defoaming tank unit 10 and the alkaline solution temporary storage tank 50 are cooled to stabilize the bubble generation of the alkaline solution.

In this stabilization step, the cooling water is circulated through the cooling coils 43 and 53 provided on the bottom surface of the defoaming tank unit 10 and the alkaline solution temporary storage tank 50, thereby preventing overheating of the alkaline solution. It is to prevent the occurrence of excessive alkali bubbles.

In addition, the present invention comprises the step of condensing and converting the alkali foam into an alkali solution in such a way that the alkali solution is stored in the alkali solution temporary storage tank 50 and returned to the alkali solution tank 211.

This process operates the transfer pumps 62 of the transfer unit 60, the operation of the transfer pumps 62 in accordance with the signal of the two-stage level sensor 86 provided in the alkaline solution temporary storage tank (50) It is done automatically.

On the other hand, the present invention preferably when the large amount of foam and solution is instantaneously supplied to the defoaming tank unit 10 according to the abnormal cleaning operation of the steel sheet, temporarily storing it in the free space of the buffer space 32 Includes adding.

That is, when the alkali solution is supplied from the alkali solution tank 211 to the defoaming tank part 10 or more, the alkali bubbles are filled to the buffer space part 32 provided on one side of the defoaming tank part 10. It is to be able to handle the excess tank foam 10 is suddenly introduced into the defoaming tank 10.

In addition, the present invention preferably further comprises the step of adjusting the bubble removal rate in the defoaming tank unit 10 by controlling the operation of the blasting unit 20 according to the foam solution level of the defoaming tank unit 10. That is, a three-stage level sensor 82 is provided inside the defoaming tank unit 10, which detects the alkali solution level of the defoaming tank unit 10 by its height, and controls the blasting unit through the control unit 80. By operating the centrifugal defoaming pumps 22 of 20, the alkaline bubbles in the defoaming tank section 10 are efficiently condensed into an alkaline solution.

In the present invention, when foam is excessively introduced into the buffer space portion 32 from the defoaming tank portion 10, the foamed buffer portion 32 is blasted by automatically detecting an excess state and spraying cooling water. Includes additional steps.

In this case, when the three-stage level sensor 82 provided inside the defoaming tank unit 10 detects the alkali solution level at the uppermost stage, the coolant spray nozzle 36 provided in the buffer space 32 is provided. Condensation conversion of the alkali bubbles located in the buffer space portion 32 into the alkali solution by spraying the cooling water to the side. At this time, three of the defoaming pumps 22 of the blast part 20 are operated to condense alkali bubbles into an alkali solution.

Hereinafter will be described in more detail with reference to the working effect of the present invention.

(Example)

In the case of the alkali cleaning process of the cold-rolled steel washing process used in the present embodiment, the alkali solution uses caustic soda (NaOH), and the alkali solution is usually made at a concentration of 2 to 5% to prepare the cleaning solution for each manufacturing operation condition of the cold rolled steel sheet. Was to use.

Looking at the properties of the cleaning solution due to the contaminants on the cold rolled steel sheet measured in the present embodiment as shown in Table 1 below, because it contains a large amount of oil and fat was very large foaming due to the saponification action.

 Table 1

Alkaline cleaning solution: pH 13.6, Turbidity 12.4 NTU, SS 4220ppm, COD 930ppm,

Oil 514ppm, surface tension (70 ℃) 29.7dyne / cm,

Conductivity 79.6mS / cm, Temperature 70 ~ 80 ℃

      Electrolytic Cleaning Solution: pH 14, Turbidity 6.3NTU, SS 810ppm, COD 300ppm,

Oil 14ppm, surface tension (80 ℃) 30.8dyne / cm,

Electrical Conductivity 174.6mS / cm, Temperature 70 ~ 80 ℃

In order to test the present invention, bubbles generated excessively on the alkali solution tank 211 for alkali antifoaming on the alkali cleaning line of the continuous annealing line in the steel mill are supplied to the defoaming tank part 10 through the connecting pipe 12. In the blast part 20 in the defoaming tank part 10, the foam was blown by the centrifugal force type defoaming pumps 22.

In this case, it was possible to process by two centrifugal defoaming pumps 22 at the rolling speed of less than 350mpm in the cold rolling cleaning process, but it was confirmed that the foam overflowed at the rolling speed of 350mpm or more and three centrifugal defoaming pumps 22 By operating the horizontal installation was able to blast the bubbles smoothly.

In addition, the cooling of the alkali solution by the cooling coils 43 and 53 confirmed that the alkali solution can be easily transferred to the alkali solution tank 211 without generating any bubbles.

In the case of the centrifugal defoaming pump 22, the interval between the surface of the residual oil cleaning liquid in the defoaming tank unit 10 and the suction port 29a of the centrifugal defoaming pump 22 during the blasting operation is detected by the level sensor 82. The level of the alkaline solution was 200-100 mm in the low condition, and 100 mm-30 mm in the high condition.

Therefore, a typical defoaming action was performed at a solution level of approximately 30 to 200 mm from the suction side of the centrifugal defoaming pump 22. At this time, the motor horsepower of the centrifugal defoaming pump 22 is 0.4kw, the rotation speed was confirmed that the most suitable rupture occurs in the range 3000 ~ 3600rpm.

As described above, according to the present invention, the alkali bubbles generated during the alkali cleaning process of the cold rolled steel mill are efficiently removed, condensed and converted into an alkaline solution, and the entire amount is recovered and reused to reduce the external discharge of the cleaning solution, The effect which can be kept comfortable is obtained.

In addition, the present invention can reduce the external discharge of the cleaning liquid as described above to prevent the corrosion of the equipment can be obtained to protect the equipment and improve the durability.

While the invention has been shown and described with respect to specific embodiments thereof, it has been described by way of example only to illustrate the invention, and is not intended to limit the invention to this particular structure. Those skilled in the art will appreciate that various modifications and changes of the present invention can be made without departing from the spirit and scope of the invention as set forth in the claims below. Nevertheless, it will be clearly understood that all such modifications and variations are included within the scope of the present invention.

Claims (12)

In the device for removing alkali bubbles generated in the steel sheet cleaning line, A defoaming tank part connected to the alkaline solution tank through a connecting pipe to receive alkali foam therein; A blasting unit provided inside the defoaming tank unit for converting the alkali foam into an alkaline solution by centrifugal force; An alkaline solution temporary storage tank connected to the defoaming tank unit through an overflow pipe to temporarily store an alkaline solution obtained from foam; A transfer unit for returning the alkaline solution from the alkaline solution temporary storage tank to the alkaline solution tank; And And a control unit for driving the blasting unit according to the bubble level of the defoaming tank unit and automatically controlling the alkali solution from the alkaline solution temporary storage tank to the alkali solution tank according to the level of the alkaline solution temporary storage tank. Alkaline defoaming device of the steel sheet cleaning line. The method of claim 1, wherein the defoaming tank unit is to increase the rupture throughput in accordance with the amount of foam when a large amount of foam and solution is instantaneously supplied therein, and in conjunction with the defoaming tank unit so as not to increase the solution level above a certain level Alkaline foam removing device of the steel sheet cleaning line, characterized in that it further comprises a buffer space portion to secure a free space on one side. According to claim 1, wherein the rupture portion is provided with three defoaming pumps mounted on the defoaming tank, two defoaming pumps are operated when the foam level of the defoaming tank is low, 3 when the foam level is high Alkaline defoaming device of the steel sheet cleaning line, characterized in that the stand is to operate. The apparatus of claim 1, wherein the defoaming tank part has a bottom surface inclined toward one side, and a coolant coil is installed on the inclined bottom surface. According to claim 1, wherein the alkaline solution temporary storage tank alkali defoaming apparatus of the steel sheet cleaning line, characterized in that the bottom surface has a cooling water coil. The apparatus of claim 1, wherein the conveying part comprises a plurality of pneumatic conveying pumps, and further comprising a washing part for preventing the conveying pump and the conveying pipe from being blocked. The method of claim 6, wherein the washing unit is connected to the cooling water pipe and the valve to the inlet pipe of the transfer pump, the drain pipe is formed on the outlet side of the transfer pump to wash the water after the operation of the pneumatic transfer pump and the transfer pipe Alkaline foam removing device of the steel sheet cleaning line, characterized in that the supply to the side to wash the inside. 3. The steel sheet cleaning line according to claim 2, wherein the buffer space part is disposed at an upper side thereof with a cooling water supply pipe and a spray nozzle to deflate the alkali bubbles by supplying the cooling water to the excess alkali bubbles introduced into the buffer space part. Alkaline defoamer. In the method for removing alkali bubbles generated in the steel sheet cleaning line, Introducing bubbles of the alkali solution tank into the defoaming tank section having a predetermined internal space; Detonating and converting the alkali bubbles in the defoaming tank into an alkali solution so as to remove the bubbles introduced into the defoaming tank; Moving the alkaline solution from the defoaming tank part to an alkaline solution temporary storage tank when the alkali solution reaches a predetermined level; Cooling the alkali solution in the defoaming tank portion and the alkaline solution temporary storage tank to stabilize foaming of the solution; And And returning the alkaline solution in the alkaline solution temporary storage tank back to the alkaline solution tank. 10. The steel sheet cleaning line according to claim 9, further comprising: temporarily storing a large amount of foam and a solution in the free space of the buffer space part according to the abnormal cleaning operation of the steel sheet into the defoaming tank part. How to remove alkali bubbles. 10. The method of claim 9, further comprising adjusting the bubble removal rate in the defoaming tank by controlling the operation of the blasting part according to the bubble solution level of the defoaming tank. 10. The steel sheet cleaning according to claim 9, further comprising the step of blasting the foam in the buffer space part by automatically detecting an excess state and injecting cooling water when the foam is excessively introduced from the defoaming tank part to the buffer space part. How to remove alkaline foam from the lines.

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