JPH0448876B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spray-type surface treatment method used for degreasing, cleaning, phosphate treatment, etc. of metal surfaces, and particularly to an energy-saving and water-saving surface treatment method.

As a pre-treatment method for degreasing metal products, phosphate treatment, etc., the tunnel-shaped booth is divided into multiple spray chambers, each spray chamber is equipped with a spray mechanism and a reservoir tank for spray liquid, and the objects to be treated are sprayed with chemicals. A method of washing and chemical conversion treatment is carried out while sequentially transporting the material from the treatment zone to the next water washing zone using a conveyor.

In this treatment method, in order to prevent the cleaning effect from decreasing due to an increase in the amount of chemicals brought into each washing zone, conventionally, fresh water is supplied to the final zone of each washing zone and overflows to the previous zone in order. Drainage was being carried out from the first cleaning zone following the chemical zone. For this reason, drainage is constantly generated,
It was necessary to treat this wastewater. As a countermeasure to this problem, a system has been proposed in which steam is discharged from the upper part of the chemical zone and evaporated to balance the amount of surplus water supplied. Although this method has certain effects, it has the following drawbacks.

The amount of evaporation must be adjusted according to the amount of surplus water, which is difficult to control and difficult to balance.

In order to discharge excess water through evaporation, a large exhaust capacity is required, but the amount of evaporation is insufficient and it is difficult to produce waste water.

As the essential feature is that steam is discharged directly above the chemical zone, it is impossible to prevent mist from being brought into the washing zone from the chemical zone, leading to uneven contamination of the object to be treated and high contamination of the washing water.

In addition, in the conventional method of actively creating surplus water using an overflow method, a liquid tank for evaporating excess water is attached to the tank in the most upstream chemical zone, and the liquid that overflows from the main tank in the chemical zone is heated and evaporated using a heater. It has also been proposed to exhaust the excess water from an exhaust duct connected to the evaporation tank, but this method also uses a large amount of water because it is based on generating excess water in an overflow manner, and it is difficult to dispose of the excess water. This is done in a dedicated evaporation liquid tank, which requires a special tank and heater, and a large-capacity exhaust fan, and the amount of evaporation needs to be adjusted according to the amount of excess water, making it extremely difficult to control. ,
Since this type of treatment requires continuous operation for 8 hours or more, there is a problem in that the balance is disrupted and excess wastewater is produced, or else the tank becomes empty.

The present invention eliminates the drawbacks of this type of system as described above, does not generate surplus water, and can efficiently save water with a small amount of displacement spray water.
It is an object of the present invention to provide an energy-saving and water-saving surface treatment method that can reliably prevent spray mist from being taken out to the subsequent zone, significantly reduce uneven contamination of the object to be treated, and can substantially eliminate wastewater with extremely little water contamination. It is something to do.

In order to achieve this objective, the present invention first creates surplus water in the final cleaning zone, supplies this in an overflow manner to the chemical tank, and evacuates the surplus water in the chemical zone, as in conventional systems. The amount of water taken out as vapor from the chemical zone and the amount of water that adheres to the surface of the workpiece and taken out is replenished, and from the next stage onwards, the amount of water corresponding to the decreased amount of water is also supplied, and the cleaning water is The supply method is to spray at the outlet side of each zone using a bypass pipe that branches from the spray pipe of the next washing zone.

Moreover, this spray amount is set at a specific ratio in relation to the amount of spray water in the next stage cleaning zone, and specifically, the amount of cleaning water sent to the spray room of each zone and the amount of spray water sent to the previous stage spray room. The ratio of the amount of washing water sent to the washing water is set in the range of 100: (1 to 0.1). This increases the water washing efficiency, minimizes the amount of chemical solution or washing water brought in from the front zone, eliminates the disadvantages of the surplus water supply system, and enables truly effective water-saving pretreatment.

Furthermore, one of the substantial features of the present invention is that the generated steam is sucked and exhausted in the chemical liquid zone or at an intermediate position between the chemical liquid zone and the next stage water washing zone. By arranging the suction position of the generated steam in the upper air portion, the flow of air and mist in each washing zone is directed toward the chemical liquid zone, and it is possible to reliably prevent the introduction of spray mist.

That is, the present invention provides a spray-type surface treatment method in which a metal surface is treated with an aqueous solution containing a chemical agent and then washed with water in multiple stages. The steam is sucked and exhausted, and the amount of water commensurate with the amount of evaporated water and the moisture adhering to the object to be treated is supplied by a bypass pipe branched from the spray piping of the next stage washing zone, and the ratio of the spray amount between the next stage and the water washing zone is maintained. (1 to 0.1): Replenish the spray to the outlet side of the chemical zone so that the amount of water is 100, and supply water corresponding to the decreased water volume in the washing zone to the bypass pipe branched from the spray piping of the next washing zone. The ratio of spray water amount to (1 to 0.1):
The process of replenishing the spray to the exit side of the front zone is repeated so that the amount of water is 100, and at the exit of the final zone, the amount of water corresponding to the decrease in the amount of water in the front stage is replenished by spraying, thereby significantly saving water and preventing contamination of the cleaning zone at the same time. can be achieved effectively.

Embodiments of the present invention will be described below based on the accompanying drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a spray-type degreasing chemical conversion treatment. In the drawing, 1 is a tunnel-shaped booth, and 2 is a conveyor for conveying the object A to be treated within the booth. The inside of the booth is divided into a plurality of spray zones, and in this embodiment, from the charging side of the processed material A, there are a preliminary degreasing zone 3A, a degreasing zone 3B, a first water washing zone 3C, and a second water washing zone 3.
D, 3rd washing zone 3E, chemical conversion zone 3F, 4th
A washing zone 3G, a fifth washing zone 3H, a sixth washing zone 3I, and a final washing zone 3J are formed.

Spray nozzles 4A-4J are provided in each of the zones 3A-3J, and liquid tanks 6A-4J are connected to the spray nozzles 4A-4J via pumps 5A-5J and feed pipes 9A-9J at the bottom.
6J is provided.

Each of the liquid tanks 6A, 6B, and 6F in the preliminary degreasing zone 3A, degreasing zone 3B, and chemical conversion zone 3F is provided with a chemical solution heating means (not shown) such as an immersion tube burner. The preliminary degreasing zone 3A and the degreasing zone 3B are connected by a passage pipe 7, and each end of a circulation system 26 including filters 23, 23', a pump 24, and a flotation tank 25 are connected. In addition, the feed pipe 9F of the chemical conversion zone 3F
A circulation system 28 equipped with a sludge filter 27 connects the liquid tank 6F and the liquid tank 6F.

The degreasing zone 3B, the first washing zone 3C, the second washing zone 3D, the chemical conversion zone 3F, the fourth washing zone 3G, the fifth washing zone 3H and the sixth washing zone 3I have a section behind the spray nozzle in each zone. That is, the replenishment spray nozzles 8B, 8C, 8D, 8F, 8G, 8H,
8I is inserted, and the replenishment spray nozzle 8B in the degreasing zone 3B moves backward through the first washing zone 3C by a bypass pipe 9C and connects the liquid tank 6C of the first washing zone 3C and the spray nozzle 4C with the feed pipe 9C. Similarly, the first water washing zone 3C
The replenishment spray nozzle 8C is connected to the feed pipe 9D of the second washing zone 3D by a bypass pipe 9d, and the replenishment spray nozzle 8D of the second washing zone 3D is connected to the feed pipe 9 of the third washing zone 3E by a bypass pipe 9e.
It is connected to E.

Further, the replenishment spray nozzle 8F at the exit position of the chemical conversion zone 3F is connected to the feed pipe 9G connecting the liquid tank 6G of the fourth washing zone 3G and the spray nozzle 4G by a bypass pipe 9g, and similarly, The replenishment spray nozzle 8G is connected to the feed pipe 9 of the fifth water washing zone 3H by a bypass pipe 9h.
H, the replenishment spray nozzle 9H in the fifth washing zone 3H is connected to the feed pipe 9I of the sixth washing zone 3I by a bypass pipe 9i, and the replenishment spray 8I in the sixth washing zone 3I is connected to the final washing zone 3J by a bypass pipe 9j. They are respectively connected to the feed pipes 9J.

As described above, in the present invention, makeup spray water is forwarded using a bypass pipe branched from the feed pipe, and the feed pipe is simply extended to connect the spray nozzle of the zone concerned and the reinforcing spray nozzle to the preceding zone. When these are written in series, good mist formation cannot be achieved because the amount of replenishing water is small. If configured as in the present invention, the pump pressure can be used efficiently to perform the spraying of the zone concerned and the make-up water spraying to the preceding zone under equal pressure conditions, thereby achieving the desired cleaning dilution effect. .

And each of the bypass pipes 9c, 9d, 9e,
9g, 9h, 9i, 9j have control valves 10C, 10D, 10E, 1 consisting of solenoid valves, etc.
0G, 10H, 10I, 10J are provided respectively, and the control valve 10C of the bypass pipe 9c
is activated by a signal from the level switch 11A installed in the liquid tank 6A of the pre-degreasing zone 3A, and the replenishment spray nozzle 8B supplies the amount of replenishment water so as not to generate surplus water.
It is now being supplied to In addition, the control valve 10D of the bypass pipe 9d is a level switch 11C provided in the liquid tank 6C of the first washing zone 3C.
Similarly, the control valve 10E of the bypass pipe 9e is connected to the level switch 11D provided in the liquid tank 6D in the previous stage, and the control valve 10G of the bypass pipe 9g is connected to the level switch 11D provided in the liquid tank 6F of the chemical conversion zone 3F.
The level switch 11F installed in and the bypass pipe 9
h is the level switch 11G of the liquid tank 6C in the previous stage,
The bypass pipe 9i is connected to the level switch 11 of the liquid tank 6H.
H and the bypass pipe 9j are respectively connected to the level switch 11J of the liquid tank 6J to automatically control the amount of makeup water sprayed so as not to generate surplus water.

On the other hand, fresh water supply spray nozzles 8E and 8J are provided at the exit position of the third flush zone 3E and the final flush zone 3J, respectively, and each supply spray nozzle 8E and 8J has external piping 12 and 1.
3 is connected to supply tap water, pure water, etc. And replenishment spray nozzle 8
In order to prevent surplus water from being generated in the third flush zone 3E and final flush zone 3J due to replenishment from E and 8J, an abnormally high water level activation valve 14A and an abnormally low water level activation valve are installed in the external pipes 12 and 13, respectively. 1
4B is provided, and the liquid tank 6E of the third washing zone 3E
It is electrically connected to a high water level level switch 15A and a low water level level switch 15B provided in the liquid tank 6J of the final washing zone 3J, respectively.

The abnormally high water level operation valve 14A is normally open, and is closed by a signal from the high water level switch 15A to stop the supply of the liquid and at the same time to issue an alarm. The abnormally low water level operating valve 14B is normally closed, and is opened in response to a signal from the low water level level switch 15B to supply makeup water and at the same time issue an alarm.

Further, air intake portions 16A and 17 are provided at intermediate positions between the degreasing zone 3B and the first washing zone 3C and between the chemical conversion zone 3F and the fourth washing zone 3G.
The intake sections 16A and 17A on the side closer to the degreasing zone 3B or the chemical conversion zone 3F are respectively connected to an exhaust duct 20 equipped with an eliminator 18 and a load fan 19. A return pipe 22 is provided leading to zone 3F.

The above-mentioned embodiment is merely an example of the present invention, and is applicable to a degreasing process alone, a chemical conversion process alone, a degreasing and chemical conversion process, etc., and may also be applied to an increase or decrease in the number of water washing steps, omission of preliminary degreasing, hot water washing before degreasing. Naturally, this also includes additional processes.

Furthermore, although the suction/exhaust section may be located above the chemical liquid zone, it is also preferable to provide it at an intermediate position between the chemical liquid zone and the next stage water washing zone as described above, and this provides a significantly greater effect.

Next, a situation in which the present invention was implemented using the above-mentioned apparatus will be explained.

In spray-type pretreatment such as painting and plating of metal products, the object to be treated A is generally placed on the conveyor 2.
It is suspended from the booth 1 and transported from the entrance to the exit of the booth 1 at a predetermined speed, and while passing through the pre-degreasing zone 3A and the degreasing zone 3B, a predetermined degreasing liquid is sprayed by the spray nozzles 4A and 4B, and then the first water washing zone. Washing water is sprayed by the spray nozzles 4C to 4E while passing through the third washing zone 3C to the third water washing zone 3E, and the chemical solution adhering to the object to be treated is washed away, and then the chemical conversion liquid is sprayed by the spray nozzle 4F of the chemical conversion zone 3F. A chemical film is formed by
Washing is performed by spraying washing water from spray nozzles 4G to 4J in the fourth washing zone 3G to final washing zone 3J.

What is important in such a process is to improve the cleaning effect. As a countermeasure against this, the conventional method includes liquid tanks 6B to 6E from degreasing zone 3B to third washing zone 3E, and liquid tanks 6F to 6J from chemical conversion zone 3F to final washing zone 3J in the drawing.
are sequentially connected with overflow piping, and fresh water is actively overflowed in the liquid tanks 6E and 6J of the third washing zone 3E and the final washing zone 3J to create surplus water, which is sequentially sent to the previous liquid tank, and then the degreasing zone. 3B, in the chemical formation zone 3F, the excess water was evaporated in a high temperature atmosphere and was forcibly evacuated. However, this causes various problems as described above.

In order to solve this problem, the present invention advances the washing water so that surplus water is not generated and at the same time the washing efficiency is improved. In other words, as is well known, in the degreasing zone 3B and the chemical conversion zone 3F, chemical liquid is sprayed under high temperature conditions, so the spray mist is vaporized and becomes steam whose volume has expanded approximately 1500 times, but the amount of steam generated is mainly Since it is determined by the temperature of the chemical solution used in the zone, the load fans 19 and 19' are set to a discharge volume that is greater than the temperature corresponding to this temperature, and the air volume is set at an intermediate position between the degreasing zone 3B and the first washing zone 3C, and between the chemical conversion zone 3F and the fourth washing zone. They are sucked and discharged at the intermediate position of 3G.

With this exhaust system, an amount of water corresponding to the evaporated amount in the degreasing zone 3B and the chemical formation zone 3F and an amount of water corresponding to the evaporated amount of the spray mist in the connected washing zone are discharged. Since the discharge rate of those water volumes is preset at the suction position, first
The amount of water corresponding to the evaporated amount of B (the amount obtained by subtracting the amount of exhausted steam on the washing zone side from the total amount of exhausted steam) is replenished from the first washing zone 3C in the next stage, and the reduced amount of water in the first washing zone 3C is compensated for. The appropriate amount of washing water is replenished from the second washing zone 3D in the next stage, and the amount of water commensurate with the decreased water amount in the second washing zone 3D is replenished from the third washing zone 3E, which is the final zone of the degreasing process. Fresh water is replenished to this zone only in the required amount so that no surplus water is generated, that is, in an amount corresponding to the discharge water meter in the degreasing zone 3B. In order to simplify the explanation, the amount of water that adheres to the object to be treated and is brought into the next zone is omitted, but the amount of water taken out is of course added to the amount of replenishment water.

However, if the advance replenishment of washing water from each of the subsequent zones and the replenishment of fresh water to the final zone are carried out directly into the liquid tank through water pipes, no improvement in cleaning efficiency can be expected. Therefore, the present invention
Replenishment spray nozzles 8B, 8C, 8D, 8G, 8 are provided at each outlet of each zone 3C, 3D, 3G, 3H, 3I except for the degreasing zone 3B and chemical conversion zone 3F.
H, 8I are arranged, and the respective supply spray nozzles are connected to the spray nozzle feed pipes 9C, 9 on the downstream side, respectively.
Connect D, 9E, 9G, 9H, 9I, 9J with bypass pipes 9c, 9d, 9e, 9g, 9h, 9i, 9j, and spray make-up water in a spray type under conditions of equal pressure with the spray nozzle in each zone. . Also,
Replenishment spray nozzles 8E and 8J are also arranged at the exits of the final zones 3E and 3J to supply fresh water in the form of mist.

As a result, in the degreasing zone 3B, after the chemical solution is sprayed by the spray nozzle 4B from the liquid tank 6B via the feed pipe 9B, the object A to be treated is transferred to the first washing zone 3C before entering the next first washing zone 3C. 3C
Washing water is sent from the liquid tank 6C via the bypass pipe 9c and is sprayed from the replenishment spray nozzle 8B in an amount corresponding to the amount of water evaporated in the degreasing zone. Since this spray is under a high pressure equal to that of the spray nozzle in the first washing zone, a good mist is formed despite the small amount of replenishment water, and as a result, a good mist is formed in the first washing zone 3.
The chemical solution is effectively diluted before entering C, and in that state is mist-cleaned by the spray nozzle 4C of the first water washing zone 3C.

Therefore, the present invention sets the ratio of the amount of washing water sprayed from the spray nozzle 4C of the first washing zone to the amount of washing water sprayed from the replenishment spray nozzle 8B to a specific range. The amount of water for washing the spray nozzle: the amount of water for washing the replenishment spray nozzle = 100: (1 to 0.1).

This range was set based on the knowledge of the inventor; if the ratio exceeds 100:1, the amount of water supplied will be greater than the amount of water that evaporates, and not only will it not be possible to achieve a substantial water saving process, but also the chemical solution The balance is disrupted, and even if other conditions are suitable, we cannot expect the synergistic effect. On the other hand, if the ratio is less than 100:0.1, the uneven contamination of the object to be treated will not be improved, and the degree of contamination of the washing water will increase, resulting in a decrease in quality, and in this case, the effects of the present invention cannot be achieved either.

Then, at the outlet of the first water washing zone 3C, the makeup water from the second water washing zone 3D is similarly sprayed by the makeup spray nozzle 8C according to the above ratio. This process is repeated in each zone thereafter, and fresh water is sprayed by the replenishing spray 8E at the outlet of the final washing zone 3E. Therefore, in the present invention, the supply of fresh water also serves as washing dilution in the final zone.
The amount of fresh water replenished at this time corresponds to the evaporated moisture in the degreasing zone 3B, and the amount of fresh water supplied is equivalent to the evaporated water in the degreasing zone 3B.
A and 15B control the amount of water in the liquid tank 6E.

Therefore, no surplus water is generated or discharged to the outside. Note that the same applies to the chemical conversion step, and the explanation will be omitted to avoid duplication, but the difference in this step is that the amount of adhering water brought in from the previous stage is offset by the amount of water waiting for the next stage.

The above is one of the features of the present invention, but simply placing a replenishment spray nozzle at the outlet of each zone and using it in conjunction with cleaning with the main spray nozzle will not allow the mist from the replenishment spray at the outlet to spread to the next zone. However, it is difficult to expect true improvement in water washing efficiency. However, in the present invention, as mentioned above,
The steam is exhausted from the degreasing zone 3B and the first water washing zone 3.
Since the degreasing is carried out at an intermediate position between the degreasing zone 3B and the fourth washing zone 3G, the steam generated in the degreasing zone 3B and the chemical converting zone 3F is
The spray curtains formed in these zones will suck and exhaust the air while encountering moderate resistance, and as a result, the inside air from the first washing zone 3C onwards and the fourth washing zone 3G onwards becomes negative pressure.
Air flows in the first water washing zone and the fourth water washing zone and the subsequent water washing zones are directed toward the degreasing zone and the chemical conversion zone, respectively.

Therefore, even if make-up water is sprayed at the outlet of each zone, the mist will not be carried over to the next zone, and the highly concentrated taken-out liquid attached to the object to be treated will be reliably washed away with the mist from the next zone. be able to. Introducing air from the ceiling of each zone by a fan only has the effect of reducing contamination of the conveyor by droplets, but is not effective in preventing mist from being introduced.

Next, specific examples of the present invention will be described.

EXAMPLES Degreasing and chemical conversion treatments were carried out according to the method of the present invention using the apparatus shown in FIG. The object to be treated is the surface area
0.15 m ² /piece of automobile parts were processed at a rate of 2000 pieces per hour. An alkaline degreasing agent was used as the degreasing agent, and a zinc phosphate type forming agent was used as the forming agent, and each was placed in a liquid tank, and the liquid temperature was controlled to 50° C. using an immersion tube burner.

Degrease the intake part with degreasing agent (chemical side): washing side = 6:4
The nominal capacity of the limit load fan is provided in the middle part between the degreasing zone and the first washing zone, and the middle part between the chemical conversion zone and the fourth washing zone so that the ratio is as follows.
155M ³ /min×140mmAq (degreasing process), 132M ³ /
Evacuation was performed at min x 160 mmAq (chemical formation process).

The amount of steam discharged from the suction section was approximately 230/H due to the relationship between the liquid temperature and the exhaust position, and the amount taken out due to adhesion of objects to be treated was 30/H.
Therefore, 220/H washing water was sprayed from the liquid tank of the first washing zone to the outlet of the degreasing zone via the bypass pipe and replenishment spray, and 30000/H spraying (100:0.7) was performed in the washing zone.
Similarly, 240/H was supplied to the outlet of the first flushing zone from the liquid tank of the second flushing zone using a bypass pipe and a replenishing spray nozzle, and to the outlet of the third flushing zone by a replenishing spray via external piping.
Tap water was sprayed at 240/H, and 30000/H (100:0.8) was also sprayed in the washing zone.

In addition, the amount of wastewater discharged from the intake part of the chemical conversion process is
At 180/H, the amount of water brought in due to adhesion and the amount of water taken out are offset, so 180/H washing water is sprayed from the liquid tank of the fourth washing zone to the outlet of the chemical conversion zone via the bypass pipe and replenishment spray to perform washing. In the zone, 26000/H spray (100:
0.7) was performed. The following equal amounts of washing water were sequentially sprayed from the latter liquid tank to the outlet of the former zone using a bypass pipe and a replenishment spray, and the washing zone was similarly sprayed at 26,000/h. The final water washing zone was sprayed with pure water at 180/h.

As a result of the above operations, the amount of replenishment water is 420
/H, which is about 1/20 or less than when fresh water is supplied in each zone, and 1/2 compared to the conventional method in which fresh water is left in excess in the final zone and is sent forward to an overflow or overspray system. ~1/3
It was below. Further, the amount of degreasing agent used was reduced by 1/3 to 1/4 or less, and the amount of chemical converting agent was reduced by 20 to 30% or more, and the degreasing state of the treated object and the state of the chemical conversion film were good.

This does not produce any excess water, and
Makeup water at an appropriate ratio is introduced from the next stage to the outlet of the previous stage to wash and dilute the adhering liquid on the surface of the workpiece, and the intake characteristics prevent the mist of make-up water from being brought into the next stage, resulting in no change in the chemical solution and stability. This is due to synergistic effects such as

According to the present invention as described above, in the spray type surface treatment method, the amount of water commensurate with evaporation in the chemical zone is sequentially replenished from the next stage onward, and the supply is carried out upstream by a bypass pipe branched from the spray piping in the downstream zone. The water should be sprayed on the outlet side of the side zone, and the ratio of the amount of make-up water to the amount of spray water in the next flushing zone should be (1).
~0.1): 100, which satisfies both the requirements for cleaning dilution efficiency of the liquid adhering to the surface of the workpiece and reducing the amount of chemical solution and cleaning water brought in from the front zone, and also the suction and exhaust position. Due to the synergistic effect of limiting the amount of water and forcing the airflow to go upstream by creating a negative pressure, the system uses the smallest amount of water without excess water, and also prevents spray mist from being carried out to the downstream stage and uneven contamination. An excellent effect can be obtained in that surface treatment can be performed at low cost with water washing efficiency.

[Brief explanation of drawings]

FIG. 1 is a longitudinal side view schematically showing the energy-saving and water-saving surface treatment method of the present invention. 3B... Degreasing zone, 3C... First washing zone, 3D... Second washing zone, 3E... Third washing zone, 3F... Chemical conversion zone, 3G... Fourth washing zone, 3H... Fifth washing zone. Zone, 3I...6th
Washing zone, 3J...Final washing zone, 4A~4
J...Spray nozzle, 6A~6J...Liquid tank, 8
B~8J...Replenishment spray nozzle, 9A~9J...
...Feed pipe, 9c to 9e, 9g to 9j...Bypass pipe, 16A, 17A...Intake part.

Claims (1)

[Claims] 1. Treat the metal surface with an aqueous solution containing a chemical agent,
Next, in a spray-type surface treatment method that performs multiple stages of water cleaning, the generated steam is sucked and exhausted in the chemical zone or at an intermediate position between the chemical zone and the next water washing zone, and this evaporated content and moisture attached to the object to be treated are removed. A bypass pipe branched from the spray piping of the next stage flushing zone is used to supply the amount of water corresponding to the amount of water sprayed in the next stage flushing zone, and the ratio to the spray water volume of the next stage flushing zone is (1 to 0.1):
The spray is replenished to the exit side of the chemical zone so that the amount of water is 100, and the amount of water commensurate with the decreased water amount in the washing zone is supplied through a bypass pipe branched from the spray piping of the next washing zone, and the amount of spray water is increased in proportion to the spray water amount in the next washing zone. This is an energy-saving water-saving system characterized by repeating the spray replenishment process to the exit side of the front zone so that the ratio is (1 to 0.1): 100, and then replenishing the water volume at the exit side of the final zone by spraying the amount of water commensurate with the amount of water reduced in the front stage. Surface treatment method.