JP2702523B2 - Processing solution thermostat - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an improvement of a thermostatic apparatus for maintaining a thermostat of a pretreatment liquid in a chemical conversion treatment by a dipping method performed before painting a surface of an automobile body or the like. About.

(Prior Art) Conventionally, for example, in order to impart rust resistance to a steel plate of an automobile body or the like and enhance coating film adhesion, a chemical conversion treatment of the steel plate is performed before electrodeposition coating or the like. This chemical conversion treatment uses a pretreatment liquid containing phosphate as a main component, and as shown in FIG. 2, a main tank 101 is filled with a pretreatment liquid 102, and a transport path 103 provided above the main tank 101 is provided. When the object 105 placed on the hanger 104 passes through the container, the substrate is generally immersed in the main bath processing liquid 102 to be processed. At this time, this treatment liquid is heated and used in order to efficiently and uniformly finish the surface treatment. That is, the processing liquid is led from the outlet pipe 107 of the overflow tank 106 arranged in parallel to the main tank 101 to the passage of the heat exchanger 108, heated by the high-temperature fluid circuit 109 formed in the other passage, and passed through the inlet pipe 110. It is returned to the main tank 101 and circulated.

On the other hand, at the time of this surface treatment, sludge such as a phosphate compound is generated in the treatment liquid, and the sludge is mixed into the overflow tank 106, enters the outlet pipe 107, and adheres to the inner wall of the passage of the heat exchanger 108. There was a problem. For this reason, in order not to lower the efficiency of heat exchange, the line was periodically stopped and washed with an acid such as nitric acid to dissolve the sludge.

Although not a heat exchanger for such an immersion treatment liquid, an apparatus as disclosed in, for example, JP-A-61-122497 is also known as a cleaning apparatus for a single heat exchanger of another apparatus. In this case, the high-temperature gas passing through the heat exchanger is rapidly cooled by heat exchange and turned into steam, and corrosive condensed water containing harmful components accumulates in the passage pipe, and the harmful components adhere to the inner wall and have an adverse effect. Is to collect the condensed water accumulated in the inside, detect the concentration of a specific component in the collected water, and when the concentration exceeds a certain value, automatically wash the washing by flowing a washing liquid.

(Problems to be Solved by the Invention) However, in the case of the conventional thermostat of the coating pretreatment liquid, it is necessary to deactivate the line in order to clean the heat exchanger, and to disassemble and clean with an acid such as nitric acid. Since the work has to be performed manually, it takes a lot of man-hours and involves risks. Furthermore, forgetting to wipe off after pickling has caused corrosion and the like. Further, even in the apparatus as disclosed in JP-A-61-122497, the point that the apparatus must be deactivated during cleaning is the same as the conventional pretreatment liquid constant temperature apparatus.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a method in which a processing liquid is derived from a liquid tank filled with a chemical conversion processing liquid and is returned to the liquid tank again. Liquid circulation line having a plurality of heat exchangers arranged in a manner capable of switching the flow paths, a cleaning circuit connected to the processing liquid circulation line, and a ventilation and water passage circuit. In the constant temperature device, air and water are selectively supplied to the treatment liquid circulation pipe, and a water supply pipe is provided,
In addition, a discharge pipe for discharging sludge and the like together with the air and water by supplying air and water to the ventilation and water pipe is provided so as to be connected to the ventilation and water pipe.

(Operation) When it is necessary to wash one heat exchanger, a chemical conversion treatment can be performed using another heat exchanger, and there is no need to stop the line. In addition, the washing work can be surely washed by sequentially passing the washing liquid, air and water,
If air is flowed at the end, there is no need to wipe off the cleaning liquid. Further, a combination having a high scraping effect such as a gas-liquid two-phase flow is also possible.

(Example) An example of the processing liquid constant temperature apparatus of the present invention will be described with reference to the attached drawings.

FIG. 1 shows a system diagram of a coating pretreatment apparatus using a constant temperature apparatus of the present invention. FIG. 1 (A) shows a pipe diagram of the constant temperature apparatus, and FIG. 1 (B) shows a solenoid valve provided in the pipe. FIG. 5 is an explanatory diagram showing connection of only one heat exchanger side in a control circuit to be performed.

The workpiece 1 is placed on a hanger 3 moving on a transport path 2, passes through a processing solution 5 on a main tank 4, and is subjected to surface treatment.
The processing liquid 5 is used at an elevated temperature. For this reason, a constant temperature device 7 is connected to the main tank 4 and an overflow tank 6 provided adjacent to the main tank 4.

The constant temperature device 7 includes a processing liquid circulation circuit 10 for circulating the processing liquid 5 and a cleaning liquid circuit for supplying nitric acid as a cleaning liquid.
20 and a ventilation / water passage circuit 40 capable of selectively supplying compressed air and industrial water. The solenoid valves, pumps, etc. provided in these circuits 10, 20, 40 are controlled by a control circuit 50 shown in FIG. Automatically controlling.

The processing liquid circulation circuit 10 is configured by connecting the overflow tank 6 and the main tank 4, and a discharge pump 12 is provided in the middle of a discharge pipe 11 connected to the overflow tank.
Branches into two inlet connection pipes 13a and 13b, and each solenoid valve 14
a and 14b are connected to the inlets A of the respective heat exchangers 15a and 15b. That is, the processing liquid circulation circuit 10 is provided with two heat exchangers 15a and 15b in parallel, and their flow paths can be switched. The heat exchangers 15a, 15b are connected to hot water passages 16a, 1
The treatment water from the inlet A to the outlet B can be heated by the hot water. Further, the outlet B is connected to respective outlet connection pipes 17a and 17b, and after passing through the solenoid valves 18a and 18b, is combined into one introduction pipe 19. The introduction pipe 19 is connected to the main tank 4, and the processing liquid is connected thereto. It is configured to circulate.

The cleaning liquid circuit 20 includes a cleaning tank 21 for storing nitric acid used as a cleaning liquid. The cleaning tank 21 includes a pump 22 and an electromagnetic valve.
The supply pipe 24 of the cleaning liquid provided with 23 is connected to the supply pipe 24. The supply pipe 24 branches into two branch supply pipes 25a and 25b.
6a and 26b, the heat exchanger 15
Outlet connection pipes 17a, 17 between the outlet B of the a, 15b and the solenoid valves 18a, 18b
Each is connected to b. On the other hand, on the inlet connection pipes 13a and 13b side of the processing liquid circulation circuit 10, the solenoid valves 14a and 14b and the inlet A of the heat exchanger are connected.
Between them, branch discharge pipes 28a and 28b provided with solenoid valves 27a and 27b are connected, connected to one discharge pipe 29 and returned to the washing tank 21. Further, a pipe 31 provided with an electromagnetic valve 30 is connected to the supply pipe 24 between the pump 22 and the electromagnetic valve 23 in the circuit configured to circulate the cleaning liquid in this way, and a neutralization tank 33 having a stirring device 32 is provided. On the other hand, a neutralizing agent composed of caustic soda in a neutralizing agent tank 34 can be fed into the neutralizing tank 33 by a pump 35.

On the other hand, the ventilation / water passage circuit 40 is provided with a water passage pipe 42 having an electromagnetic valve 41.
Then, a single vent pipe 44 having an electromagnetic valve 43 is provided, and then branched into branch vent / water pipes 45a and 45b, and electromagnetic valves 46a and 46b are provided respectively and connected to the outlet connection pipes 17a and 17b. . This connection point is selected between the connection points between the solenoid valves 18a and 18b and the branch supply pipes 25a and 25b of the cleaning liquid circuit 20 described above. In addition, ventilation / flow pipes 47a, provided with solenoid valves 48a, 48b also at the inlet connection pipes 13a, 13b,
47b is connected between the solenoid valves 14a and 14b and the branch discharge pipes 28a and 28b of the washing liquid circuit 20. Each of the ventilation / water pipes 47a and 47b is connected to a single discharge pipe. 49
Connected to

The control circuit 50 is provided for automatically controlling the treatment liquid circulation circuit 10, the cleaning circuit 20, and the ventilation / water passage circuit 40 as described above, and for automatically cleaning the heat exchangers. Fifteen
b) a pressure gauge 51 attached to the processing liquid circulation circuit near the inlet A and the outlet B, and a controller 52 for controlling an electromagnetic valve or the like based on a difference between the pressure P1 on the inlet side and the pressure P2 on the outlet side. Are connected to the respective solenoid valves as shown in FIG. FIG. 2B shows the connection on only one heat exchanger 15a side.

An example of an outline of the operation of the processing liquid constant temperature apparatus configured as described above is as follows.

When the sludge adheres to the passage on the side of the heat exchanger 15a and the inner diameter is reduced, a pressure difference is generated between A and B, a signal detected by the pressure gauge 51 is sent to the controller 52, and automatic cleaning is started. First, in order to close the processing liquid circulation circuit on the heat exchanger 15a side, the solenoid valve 14a of the inlet connection pipe 13a and the solenoid valve 18a of the outlet connection pipe 17a are closed. Next, the electromagnetic valves 43, 46a, 48a of the ventilation / water passage circuit 40 are opened, and the processing liquid remaining in the pipeline is discharged from the discharge pipe 49 by air. Then the above solenoid valve
When closing 43, 46a, 48a, the solenoid valves 23, 26a, 27a of the cleaning liquid circuit 20
Is opened, and the pump 22 is operated to circulate the nitric acid in the washing tank 21 to dissolve and wash the sludge that adheres. When the pickling for a predetermined time is completed, the remaining solenoid valve 2 is left, leaving the solenoid valve 27a.
The solenoid valves 43 and 46a are opened by closing the valves 3 and 26a, and the remaining acid is pumped to the washing tank 21 by ventilation. After that, when the solenoid valve 43 is closed to terminate the ventilation, the solenoid valve 41 of the water pipe 42 is opened to wash with water, and this is also sent to the washing tank 21. Finally, the solenoid valves 41 and 27a are closed except for the solenoid valve 46a, and the solenoid valves 43 and 48a of the ventilation pipe 44 are opened to discharge all the residue from the discharge pipe 49 by air.

On the other hand, the nitric acid in which the sludge in the cleaning tank 21 is dissolved is sent to the neutralization tank 33, neutralized by stirring together with the caustic soda sent from the neutralizing agent tank 34, and discharged out of the system.

It should be noted that it is also possible to adopt a cleaning method that simultaneously performs ventilation and water passage in the ventilation / water passage circuit and has a high scraping effect as a gas-liquid two-phase flow.

During this time, the other heat exchanger 15b is operating normally, and the constant temperature of the processing solution in the main tank is maintained.

(Effects of the Invention) The present invention is configured such that the cleaning liquid, air, and water can be selectively supplied to the passages of the plurality of heat exchangers arranged in parallel as described above. Can be performed without stopping the line as in the prior art. In addition, since the washing can be performed automatically and easily, the number of man-hours can be reduced, and it is not necessary to directly handle dangerous chemicals such as nitric acid, which is effective for disaster prevention.

Also, the present invention provides a ventilation and water supply pipe for selectively supplying air and water to the treatment liquid circulation pipe, and supplies the air and water to the ventilation and water supply pipe together with the air and water. The exhaust pipe for discharging sludge etc. is provided so as to be connected to the ventilation and water passage pipes, so that air and water are ventilated to the treatment liquid circulation pipe and supplied to the water pipe, so that sludge is mixed with air and water. Can be discharged from the discharge pipe, and the inside of the heat exchanger can be washed while maintaining the temperature of the processing liquid stably without stopping the work of heating the processing liquid.

[Brief description of the drawings]

FIG. 1 shows a system diagram of a coating pretreatment apparatus using a constant temperature apparatus of the present invention. FIG. 1 (A) shows a pipe diagram of the constant temperature apparatus, and FIG. 1 (B) shows a solenoid valve provided in the pipe. FIG. 2 is an explanatory diagram showing a connection on one heat exchanger side in a control circuit to be performed, and FIG. 2 is a system diagram showing a conventional example. In the figure, 1 is an object to be processed, 4 is a main tank, 5 is a processing liquid, 7 is a thermostat, 10 is a processing liquid circulation circuit, 15a and 15b are heat exchangers, 2
0 is a washing liquid circuit, 21 is a washing tank, 40 is a ventilation / water passage circuit, 42
Is a water pipe, 44 is a vent pipe, 49 is a drain pipe, 50 is a control circuit, 10
1 is a main tank, 108 is a heat exchanger, and 109 is a high-temperature fluid circuit.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masuri Masao 2-6-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo In-house Daiki Co., Ltd. (72) Inventor Susumu Yoshida 2-6-Nishishinjuku, Shinjuku-ku, Tokyo No. 1 Daiki Co., Ltd. (56) References JP-A-60-194083 (JP, A)

Claims (1)

(57) [Claims] 1. A heat exchanger comprising a plurality of heat exchangers disposed in parallel and switchable in the middle of a circulation pipe for drawing out a processing liquid from a liquid tank filled with a chemical conversion processing liquid and returning the processing liquid to the liquid tank again. A processing liquid circulation line having a vessel, a cleaning circuit connected to the processing liquid circulation line, and a ventilating, a constant temperature apparatus for processing liquid provided with a water passage circuit, wherein the processing liquid circulation line has air, and A vent and a water pipe are provided for selectively supplying water, and a discharge pipe for discharging sludge and the like together with the air and the water by supplying the air and water to the water and the water pipe is provided with a vent and a water pipe. A constant temperature device for a processing liquid, which is provided so as to be connected.