JPH0211680B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for cooling a liquid in an electrolytic cell in an aluminum surface treatment apparatus comprising a plurality of anodizing electrolytic cells.

The object to be treated, such as aluminum material for building materials, is immersed in an anodizing electrolytic bath (hereinafter referred to as the electrolytic bath), and the anode of the power supply device is connected to the object to be treated, and the cathode is connected to the cathode plate to supply power. In anodizing equipment that performs electrolytic treatment, the temperature of the treatment liquid in the electrolytic cell increases due to Joule heat and oxidation heat generated during electrolytic treatment. And to prevent temperature rise,
The electrolyte undergoes heat exchange with cold water obtained from a refrigerator, and the temperature is always adjusted to, for example, 20°C ± 1°C.

By the way, to explain the conventional method with reference to Fig. 1, in the example shown, there are five electrolytic cells 1 _A , 1 _B , ... 1 _E , and the electrolytic solution with a liquid temperature of 21°C overflows and is discharged from each electrolytic cell. are collected in an overflow tank 9 via piping 5, and then each liquid circulation pump 7 _{A to E} and each heat exchanger 4 _{A to E} are arranged for each electrolytic cell.
The liquid was cooled by water and returned to each electrolytic cell _{1A to E} at a liquid temperature of 19°C. The numbers in parentheses for piping 5 in the figure illustrate the liquid temperature.

However, in recent years, in large-capacity production equipment, if there is a heat load of 600,000 Kca/Hr per electrolytic cell, a liquid circulation pump of about 300,000 Kca/Hr is required for a temperature difference of 2°C, and the liquid circulation pump is required to circulate the liquid through a heat exchanger to the electrolytic cell. The pump height for blowing out is approximately 20M (2Kg/cm ² )
Therefore, the motor capacity is 30Kw, and if there are 5 electrolyzers, the total motor capacity is 150Kw.

The present invention eliminates the increase in power costs as described above, and also
The purpose is to reduce equipment costs and stabilize the coating performance of the treated material, and the details will be explained below with reference to the drawings.

FIG. 2 shows an arrangement of five electrolytic cells having the same capacity as the electrolytic cell shown in FIG. 1. In the figure, 1 _{A to E} indicate the electrolytic cell 1 having five cells. The electrolytic solution discharged from each of the electrolytic cells 1A _{to 1E} , for example, at a liquid temperature of 21.degree. C., is collected in one cooling mixing tank 2 via a pipe 5. As will be described later, during steady state operation, the temperature of the liquid in the cooling mixing tank 2 has dropped to 19°C, so a portion of the electrolyte in the cooling mixing tank 2 is pumped to one heat exchanger 4 by the pump 3. pump it to
The liquid temperature is lowered to 14° C. (supercooled) and the liquid is sent into the cooling mixing tank 2. Through this operation, the liquid temperature in the cooling mixing tank remains almost constant even though the electrolyte at 21°C always flows into cooling mixing tank 2 during operation.
It can maintain a temperature of 19℃. As a result of experiments, it was possible to obtain a uniform temperature in the cooling mixing tank 2 by natural stirring without particularly providing a stirring device.

To explain in detail with reference to FIG. 3, a temperature sensor 10 connected to a temperature controller 8 is inserted into the cooling mixing tank 2, and the heat exchanger receives instructions from the temperature controller 8. The flow rate on the cold water side of 4 is automatic valve 11.
Adjusted by. For example, the electrolytic solution is supercooled to 14°C in the heat exchanger 4 using cold water cooled to 7°C (not shown) and returned to the mixing tank 2, so that 21
Despite the inflow of electrolyte at ℃, mixing tank 2
The temperature of the liquid inside the tank is constantly maintained at 19°C.

In addition, 7℃ cold water is heated to 12℃ by heat exchange with the electrolyte.
℃, cooled again, and circulated.

As explained above, the electrolytic solution in the cooling mixing tank 2 whose temperature is adjusted to a constant temperature of 19°C is directly returned to each electrolytic tank 1 _A to E by the five liquid circulation pumps 7 _{A to E} for each tank. be done. As a result, the electrolytic cell can always maintain a liquid temperature of 20℃±1℃. Note that the numbers shown in parentheses for the pipe 5 indicate the liquid temperature.

As mentioned above, instead of controlling each electrolytic cell individually, by collectively cooling the liquid in the cooling mixing tank 2 where liquid from multiple electrolytic cells gathers, the liquid is circulated to each electrolytic cell 1 with the liquid temperature in the tank at 19 ° C. If you blow it out with pump 7,
The capacity of the motor 9 of the 300,000/Hr liquid circulation pump is reduced by the amount that does not pass through each heat exchanger 4, and the pump head becomes approximately 1M (1Kg/cm ² ), which is approximately 18MKw. Therefore, if there are 5 electrolytic cells, it becomes 90KW. Even if we add the 22Kw of pump 3 that pumps to the one heat exchanger, it is only 112Kw, which is a difference of 38Kw compared to the conventional method, making it possible to save 4 million yen in annual electricity costs. In addition, the temperature controller 8 and heat exchanger 4 can be placed in one place, resulting in a reduction in equipment costs.Furthermore, there is no variation in the temperature of each electrolytic cell _{1A to E} due to centralized control of the electrolyte, so the processing material can be It was possible to achieve effects such as uniform coating performance.

[Brief explanation of drawings]

FIG. 1 is a flowchart for cooling an electrolyte according to a conventional method. FIG. 2 is a flow chart for cooling an electrolytic solution according to the present invention. FIG. 3 is an explanatory diagram of a flowchart of a temperature controller and a heat exchanger. 1 _A~E ...Each electrolytic cell, 6...Average liquid temperature, 2...
Cooling mixing tank, 7 _A~E ...Each liquid circulation pump, 3...
Pump, 8... Temperature controller, 4... Heat exchanger, 9...
Overflow tank, 4 _{A to E} ...Each heat exchanger, 10
...Temperature sensor, 5...Electrolyte piping.

Claims (1)

[Claims] 1. In an aluminum surface treatment apparatus consisting of a plurality of anodizing electrolytic cells, the electrolytic solution discharged from each electrolytic cell is collected in a cooling mixing tank, and a part of the electrolytic solution in the cooling mixing tank is The liquid is sent under pressure to a heat exchanger via a pump, supercooled, and returned to the cooling mixing tank to lower the average liquid temperature, and on the other hand, via a liquid circulation pump, directly from the cooling mixing tank to each electrolytic tank. A liquid cooling method for an electrolytic cell characterized by returning the electrolyte.