JP4957299B2 - Steel plate cleaning equipment - Google Patents

Description

  The present invention relates to a steel plate cleaning facility that is installed in a cold-rolled steel plate production line and cleans the rolling residue on the surface of the steel plate with a chemical.

  Rolled oil, iron powder, iron soap which is a reaction product thereof, and the like adhere to the surface of the cold-rolled steel sheet. The deposits become carbide in the post-annealing process and remain on the plate surface, which is harmful in use. For this reason, the surface of the cold-rolled steel sheet is subjected to an annealing process or a plating process after the surface is cleaned.

  The steel plate is cleaned by immersing the steel plate in a cleaning solution such as an alkaline solution. The cleaning liquid is stored in a line tank through which the cold-rolled steel sheet passes. There are the following two types of general equipment configurations of conventional cleaning equipment.

  One is a cleaning facility for circulating the cleaning liquid in the line tank 21 without having a circulation tank, as shown in FIG. 6, in order to reduce the initial construction cost. By circulating the cleaning liquid, the amount of new liquid (new clean cleaning liquid) used can be reduced, and the cost can be reduced. Since the cleaning liquid in the line tank 21 is carried away by the passing steel plate, a new liquid corresponding to the cleaning liquid (new clean cleaning liquid) is supplied to the line tank 21.

The other is a cleaning facility that has a line tank and a circulation tank, returns the cleaning liquid flowing out from the overflow duct provided in the line tank liquid surface portion to the circulation tank, and circulates the cleaning liquid. Examples of the cleaning equipment having a circulation tank include a cleaning equipment (see Patent Document 1) in which a filter medium tank is installed on the return pipe from the overflow duct of the line tank, and a defoaming by using both the overflow duct and the U-shaped pipe. Cleaning equipment (see Patent Document 2) that is trying to obtain the effect, a partition plate is installed in the circulation tank to which the cleaning liquid is returned from the overflow duct of the line tank, and the scum and sludge in the circulation tank are removed. A cleaning facility that supplies the removed cleaning liquid to a line tank (see Patent Document 3) is known.
Japanese Patent Laid-Open No. 9-263379 JP-A-4-371591 JP-A-6-122987

  In any of the cleaning facilities, the steel plate deposits are washed away in the line tank, so that scum is generated in the line tank and sludge accumulates. The scum is soap generated by the reaction between the rolling oil and the alkali of the cleaning liquid, and floats softly on the liquid level of the line tank. On the other hand, sludge is mainly iron and accumulates in the line tank.

  In the former cleaning facility, sludge and floating scum generated by cleaning accumulate in the line tank. When this amount increases, the foreign matter adheres again to the steel sheet, resulting in poor cleaning. In order to prevent this, it was necessary to frequently replace and clean the cleaning liquid in the line tank.

  In the latter cleaning equipment, even if the floating scum can be discharged from the line tank, the sludge accumulates at the bottom of the line tank. In order to remove sludge, the cleaning liquid in the line tank must be frequently replaced and cleaned.

  The steel plate passes through the line tank. How to keep the cleaning liquid in the line tank clean is important for producing high-quality steel sheets. Therefore, the present invention discharges both floating scum and sludge from the line tank and returns them to the circulation tank, so that the cleaning liquid in the line tank can always be kept clean and the steel plate having the cleaning liquid can fully exhibit the cleaning ability. To provide cleaning facilities.

  In order to solve the above problems, the invention according to claim 1 is directed to a line tank through which a steel plate to be cleaned passes, a circulation tank for supplying and circulating a cleaning liquid to the line tank, and a cleaning liquid in the circulation tank. A circulation pump for supplying the line tank to the line tank, a sludge accumulated in the line tank together with a cleaning liquid, a bottom piping system for returning to the circulation tank from a discharge port provided at the bottom of the line tank, A steel plate cleaning facility comprising an overflow piping system for returning a scum together with a cleaning liquid from an overflow port provided in a liquid surface portion of the line tank to the circulation tank.

  The invention according to claim 2 is the steel plate cleaning facility according to claim 1, wherein the cleaning facility is further connected to the circulation pump, and the sludge accumulated in the line tank by ejecting a cleaning liquid from a nozzle. The liquid supply header which collects the above in the discharge port is provided.

  According to a third aspect of the present invention, in the steel plate cleaning facility according to the second aspect, the side surface shape of the bottom of the line tank is formed in a V shape having a pair of inclined surfaces, and the liquid supply header is It is provided corresponding to each of the pair of inclined surfaces.

  According to a fourth aspect of the present invention, in the steel sheet cleaning facility according to any one of the first to third aspects, sludge and cleaning liquid are circulated from the discharge port at the bottom of the line tank to the bottom piping system. A bottom valve that can adjust the opening degree is provided so that the scum and the cleaning liquid can be returned to the tank and returned to the circulation tank from the overflow port of the line tank.

  The invention according to claim 5 is the steel sheet cleaning facility according to any one of claims 1 to 4, wherein the nozzle of the liquid supply header has a flow rate of 1 to 3 m / second and is 30 degrees from the horizontal direction. The cleaning liquid is jetted downward by 60 degrees.

  According to the first aspect of the present invention, since the scum and sludge in the line tank can be discharged from the line tank at the same time, the cleaning liquid in the line tank is kept clean. Therefore, the cleaning ability of the steel plate of the line tank can be maintained for a long time. Sludge and floating scum discharged from the line tank are accumulated in the circulation tank. Usually, since the capacity of the circulation tank is larger than that of the line tank, the periodic cleaning operation can be performed in a longer cycle than when the line tank is cleaned.

  According to the second aspect of the present invention, the sludge accumulated in the line tank can be collected at the discharge port and discharged.

  According to the third aspect of the present invention, sludge accumulated in the line tank can be efficiently collected at the discharge port.

  According to the fourth aspect of the present invention, the sludge and the floating scum can be discharged simultaneously from the line tank by adjusting the opening of the bottom valve.

  According to the invention described in claim 5, sludge accumulated in the line tank can be efficiently collected at the discharge port.

  Hereinafter, a steel plate cleaning facility according to an embodiment of the present invention will be described with reference to the accompanying drawings. The steel plate cleaning equipment includes a line tank 1 through which the steel plate passes, a circulation tank 2 provided off-line, a feed piping system 3 for supplying cleaning liquid from the circulation tank 2 to the line tank 1, and a line tank 1 to the circulation tank 2. And a return piping system 4 for returning the cleaning liquid. The cleaning liquid circulates between the line tank 1 and the circulation tank 2.

  The feed piping system 3 is provided with a circulation pump 7 that supplies the cleaning liquid in the circulation tank 2 to the line tank 1. Since the line tank 1 is disposed above the circulation tank 2, the cleaning liquid supplied to the line tank 1 is returned to the circulation tank 2 by gravity. The return piping system 4 has a bottom piping system 6 for returning the cleaning liquid from the discharge port 1 a at the bottom of the line tank 1 to the circulation tank 2, and a cleaning liquid from the overflow port 1 b provided in the liquid surface portion of the line tank 1 to the circulation tank 2. And an overflow piping system 5 to be returned. The bottom piping system 6 and the overflow piping system 5 join on the way. A bottom valve 8 whose opening degree can be adjusted is provided upstream of the joining position of the bottom pipe system 6.

  The circulation tank 2 is provided with a return port 2 a connected to the return pipe system 4 and a feed port 2 b connected to the feed pipe system 3. The circulation tank 2 is provided with a lower partition plate 9 that rises upward from the bottom and an upper partition plate 10 that hangs downward from the ceiling. The lower partition plate 9 and the upper partition plate 10 are arranged in this order from the return port 2a side to the feed port 2b side of the circulation tank 2.

  The cleaning liquid including the sludge 11 and the scum 12 is returned from the line tank 1 to the return port 2 a of the circulation tank 2. Since the sludge 11 is heavier than the cleaning liquid, it settles on the return port 2a side with respect to the lower partition plate 9. The supernatant liquid from which the sludge 11 has been removed moves to the feed port 2b side with respect to the lower partition plate 9. Since the scum 12 floats on the cleaning liquid, the scum 12 is captured on the return port 2 a side from the upper partition plate 10. The lower partition plate 9 and the upper partition plate 10 are arranged in order from the return port 2a to the feed port 2b because the settled sludge rises and moves toward the feed port 2b, or the captured scum foams. This is to prevent the movement toward the feed port 2b. In the circulation tank 2, the sludge 11 and the scum 12 in the cleaning liquid are removed by the upper and lower partition plates 9 and 10. The sludge 11 and the scum 12 are removed, and the cleaned cleaning liquid is supplied to the circulation pump 7 from the feed port 2b.

  Instead of providing upper and lower partition plates in the circulation tank, the circulation tank is divided into a dirty side and a clean side, and a filtration system that connects the dirty side and the clean side is provided separately from the circulation tank. The cleaning solution may be cleaned through a filtration system and returned to the clean side.

  The detergent used for the cleaning liquid is a simple alkali or a mixture of an alkali and a surfactant / chelating agent. The alkali stock solution and water for diluting the stock solution are supplied to the circulation tank 2. The concentration of the cleaning liquid in the circulation tank 2 is managed by a concentration meter and a concentration control device (not shown). The concentration control device controls the concentration of the cleaning liquid in the circulation tank 2 by adjusting the amount of the alkali stock solution and water supplied to the circulation tank 2. The temperature in the circulation tank 2 is managed by a thermometer and a temperature control device (not shown). The temperature control device operates a heat exchanger installed in the circulation tank 2 to control the temperature in the circulation tank 2.

  2 and 3 show the line tank 1. FIG. 2 is a perspective view of the line tank 1, and FIG. 3 is a side view of the line tank 1. As shown in FIG. 3, the line tank 1 is provided with a roll 13 for dipping the steel plate 14 in the cleaning liquid. The side surface shape of the bottom of the line tank 1 is formed in a V shape having a pair of inclined surfaces 1c. The inclined surface 1c is inclined by 10 to 20 degrees (15 degrees in this embodiment) with respect to the horizontal plane. As shown in FIG. 2, a discharge groove 1d is provided in the center of the V-shaped bottom. A discharge port 1 a is provided at the lower end of the line tank 1. The bottom of the discharge groove 1d has a downward slope toward the discharge port 1a. A bottom piping system 6 is connected to the discharge port 1a. An overflow port 1 b is provided in the liquid surface portion of the side wall of the line tank 1. The overflow port 1b is connected to the overflow piping system 5.

  A pair of liquid supply headers 15 is provided corresponding to each of the pair of inclined surfaces 1 c at the bottom of the line tank 1. The pair of liquid supply headers 15 are provided at the inlet and outlet ends of the steel plate of the line tank 1. The liquid supply header 15 is disposed above the inclined surface 1c and below the liquid surface. The liquid supply header 15 is elongated in parallel with the inclined surface 1c. In the liquid supply header 15, a plurality of nozzles 15 a arranged at equal intervals in a line along the longitudinal direction are opened. In this embodiment, the nozzle 15 a is formed by a hole opened in the pipe-shaped liquid supply header 15. The nozzle 15a faces 30 to 60 degrees downward (45 degrees downward in this embodiment) with respect to the horizontal direction. The cleaning liquid is sprayed downward by 30 to 60 degrees with respect to the horizontal direction. The feed pipe system 3 is connected to the feed header 15. When the circulation pump 7 of the feed piping system 3 is operated, the cleaning liquid in the circulation tank 2 is ejected from the nozzle 15a.

  As shown in FIG. 1, when the circulation pump 7 is operated, the cleaning liquid is ejected from the nozzle 15 a of the liquid supply header 15. The sludge 11 accumulated in the line tank 1 is collected at the center of the bottom by the flow of the cleaning liquid sprayed from the nozzle 15a. The cleaning liquid is always discharged from the bottom valve 8 to the circulation tank 2. The sludge 11 collected at the center of the bottom is returned to the circulation tank 2 together with the cleaning liquid. Since the opening of the bottom drain valve 8 is adjusted so that the cleaning liquid always flows from the overflow port 1b provided in the liquid surface portion of the line tank 1, the floating scum 12 is discharged from the overflow port 1b simultaneously with the discharge of the sludge. Is done. In order to discharge the cleaning liquid from the overflow port 1b, the opening degree may be adjusted so that the amount of the cleaning liquid discharged from the bottom valve 8 is smaller than the capacity of the circulation pump 7.

  Sludge 11 and floating scum 12 discharged from the line tank 1 are returned to the circulation tank 2. In the circulation tank 2, the upper and lower partition plates 9 and 10 are alternately arranged at the bottom and the ceiling, so that the sludge 11 and the floating scum 12 are collected in the circulation tank 2. The sludge 11 and the floating scum 12 once collected are rarely supplied to the circulation pump 7. For this reason, the cleaning liquid in the line tank 1 through which the steel plate passes is always kept clean, and an environment in which the ability can be sufficiently exhibited is maintained. Moreover, cleaning in the line tank 1 is also unnecessary.

  FIG. 4 is a graph showing the optimum range of the flow rate and angle of the cleaning liquid sprayed from the nozzle 15a of the liquid supply header 15. The nozzle 15a of the feed header 15 has a role of collecting the sludge 11 accumulated in the line tank 1 at the discharge port 1a. The inventor designed and manufactured the line tank 1 and experimented with the actual machine of the line tank 1 on the relationship between the flow rate and angle of the cleaning liquid sprayed from the nozzle 15 a and the collection effect of the sludge 11. As a result, it was found that when the flow rate was 1 to 3 m / second and the angle was 30 to 60 degrees, there was an aggregation effect of the sludge 11. However, if the flow velocity is too fast than the above-mentioned range, the sludge will rise, but if it is too slow, there will be no aggregation effect. If the angle is set too low (approaching in the horizontal direction), the cleaning liquid only flows above the sludge 11, and thus the sludge 11 cannot be collected. On the other hand, when the angle is turned downward (greater than 60 degrees), the cleaning liquid hits only the sludge 11 below the liquid supply header 15, so that the sludge 11 cannot be collected in the discharge port 1a.

  FIG. 5 shows another example of the line tank. The bottom of the line tank 1 of the above embodiment is formed in a V shape having a pair of inclined surfaces 1c, whereas the bottom of the line tank 17 of this embodiment is from the entry side to the exit side of the line tank 17. It is comprised from the one inclined surface 17c which becomes a downward slope toward it. If there is one inclined surface 17c, only one liquid supply header 15 is required. Depending on the shape of the bottom of the line tank 17, the liquid supply header 15 to be installed may be provided only on either the entry side or the exit side of the line tank 17.

  The degree of cleaning of the plate surface was compared between the steel plate that passed through the cleaning equipment of the present invention and the steel plate that passed through the conventional cleaning equipment. For the degree of cleaning of the plate surface, an L value, which is an index indicating the brightness of the color, was used. The larger the L value, the brighter and more beautiful the plate surface. As a result of comparison, the L value of the conventional cleaning equipment was 70 to 80, whereas the L value of the cleaning equipment of the present invention was 90, which significantly improved the degree of cleaning of the plate surface. Also, the line tank cleaning work was performed every month in the conventional cleaning equipment, but in the cleaning equipment of the present invention, the circulation tank cleaning work was performed every six months, and the cycle could be greatly extended.

The block diagram of the washing equipment of one embodiment of the present invention Perspective view of line tank Side view of line tank Graph showing the results of experiments on the optimum values of nozzle angle and flow velocity of the feed header Side view showing another example of line tank Configuration diagram showing conventional cleaning equipment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,17 ... Line tank 1a ... Discharge port 1b ... Overflow port 2 ... Circulation tank 3 ... Feeding piping system 4 ... Return piping system 5 ... Overflow piping system 6 ... Bottom piping system 7 ... Circulation pump 8 ... Bottom valve 11 ... Sludge 12 ... Scum 14 ... Steel plate 15 ... Supply header 15a ... Nozzle

Claims (5)

A line tank through which the steel plate to be cleaned passes;
A circulation tank for supplying and circulating cleaning liquid to the line tank;
A circulation pump for supplying cleaning liquid in the circulation tank to the line tank;
A bottom piping system for returning sludge accumulated in the line tank to the circulation tank from a discharge port provided at the bottom of the line tank together with a cleaning liquid;
A steel plate cleaning facility comprising: an overflow piping system for returning the scum in the line tank together with a cleaning liquid from an overflow port provided in a liquid surface portion of the line tank to the circulation tank. The cleaning equipment further includes
The steel sheet cleaning equipment according to claim 1, further comprising a liquid supply header that is connected to the circulation pump and collects sludge accumulated in the line tank by ejecting the cleaning liquid from a nozzle to the discharge port. The side shape of the bottom of the line tank is formed in a V shape having a pair of inclined surfaces,
The steel sheet cleaning equipment according to claim 2, wherein the liquid supply header is provided corresponding to each of the pair of inclined surfaces. In the bottom piping system,
A bottom valve that can adjust the opening so that sludge and cleaning liquid can be returned from the discharge port at the bottom of the line tank to the circulation tank, and scum and cleaning liquid can be returned from the overflow port of the line tank to the circulation tank. The steel plate cleaning equipment according to any one of claims 1 to 3, wherein the steel plate cleaning equipment is provided. 5. The steel sheet according to claim 1, wherein the nozzle of the liquid supply header sprays the cleaning liquid at a flow rate of 1 to 3 m / sec and downward from 30 to 60 degrees from the horizontal direction. Cleaning equipment.

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