JPH02243797A - Electrodeposition coating device utilizing heat pump - Google Patents

Abstract

PURPOSE:To drastically improve the heat efficiency in the whole device by providing a heat pump respectively on the pretreating tank side and electrodeposition tank side of the electrodeposition coating device and efficiently combining both heat pump cycles. CONSTITUTION:When a material to be treated is washed with hot water, degreased and chemical conversion-treated in the pretreating tank B in the electrodeposition coating device, a processing soln. is heated, and an increase in the temp. of a coating soln. is cooled and controlled by the reaction heat when the material is electrodeposition-coated in the electrodeposition tank A. In this device, the pretreating tank B is heated by the solidification heat of a first heat pump C using a refrigerating load for cooling the electrodeposition tank A as a heat source, a loss in the latent heat of the low-temp. vapor liberated from the tank B is used as the heat source for a second heat pump D, and the tank B is heated by the condensation heat of the second heat pump D. Consequently, the condensation heats of both heat pumps C and D are equalized in a hot-water tank E, a two-stage compression mechanism is substantially obtained between both heat pumps, and the heat efficiency in the electrodeposition coating device is drastically improved.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to an electrodeposition coating device using a heat pump,
In particular, the present invention relates to an electrodeposition coating apparatus that effectively utilizes the heat of evaporation and condensation in a heat pump cycle to control the temperature of a pretreatment process tank and an electrodeposition tank.

``Prior Art'' Conventionally, in electrodeposition coating equipment, in order to enable smooth and quick pretreatment in pretreatment steps such as hot water washing, degreasing, and chemical conversion treatment, the treatment liquid for pretreatment has been used at a concentration of 50 to 50%. It is necessary to control the heating to 0'0, and on the other hand, in the electrodeposition tank, the coating process is applied to the object to be coated after the pretreatment is completed while electricity is applied to the coating solution, so the temperature tends to rise. If left as it is, proper coating treatment will not be possible, so it is necessary to control the cooling of the coating liquid in the electrodeposition tank to a temperature of about 25 to 30°C.

Conventionally, such heating control and cooling control were performed using independent (cold) heat sources, but since using such independent heat sources is not rational in terms of thermal efficiency, evaporation control in the heat pump cycle Heat (cooling) and heat of condensation (
Electrodeposition coating equipment has been proposed that effectively utilizes heating to control the temperature of an electrodeposition tank and a pretreatment tank. (Tokuko 1980
-33914, etc.) In order to operate such a system smoothly, it is necessary to maintain the heat balance between the evaporation side and the condensation side of the heat pump cycle.

In this case, ideally the objects to be coated placed in the pre-treatment tank and the electrodeposition tank are the same, in other words, the heat capacity to be heated/cooled is constant, so the object to be coated before being placed in the pre-treatment tank is If it is possible to maintain the temperature of the body, or in other words, the temperature of the electrodeposition bath at the same level as the environmental temperature, the heat absorption and heat absorption capacity between the evaporation side and the condensation side will be the same, and the evaporation side and the condensation side will easily It is possible to maintain the heat balance between the sides, but in reality, the environmental temperature is not only maintained at around 20 to 25 degrees Celsius (indoor air conditioning temperature), which is lower than the temperature of the electrodeposition tank, but also The temperature difference between the pretreatment tank and the environment temperature is several steps larger than the temperature difference between the electrodeposition tank and the environment temperature, and furthermore, since the tower tank is an open tank, the temperature difference with the environment temperature causes Heat loss increases further.

For this reason, the amount of heat absorbed on the pretreatment tank side is several orders of magnitude larger than that on the electrodeposition tank side, which inevitably creates an extremely large thermal imbalance between the two tanks. In this case, it was necessary to provide a boiler as an auxiliary heat source on the side of the pretreatment tank. (Special Publication No. 81-60818) "Problem to be Solved by the Invention" However, as mentioned above, it is not rational to use an independent heat source such as a boiler, even as an auxiliary heat source, from the standpoint of thermal efficiency. For this reason, even if a heat pump cycle is applied to the electrodeposition coating system, the overall thermal efficiency will be unsatisfactory.

In addition, in terms of load fluctuations, in the above-mentioned known electrodeposition coating equipment, cooling of the electrodeposition liquid and heating of the pretreatment liquid (chemical liquid and degreasing liquid) are performed by one heat pump unit, so it is difficult to cope with the load. There may be cases where it cannot be cut.

In view of the drawbacks of the prior art, it is an object of the present invention to provide an electrodeposition coating device that effectively combines two heat pump cycles without using an independent auxiliary heat source such as a boiler, thereby significantly improving thermal efficiency. purpose.

``Means for Solving the Problems'' As shown in FIG. 1, the present invention is designed to heat the pretreatment tank B side, where the amount of heat absorbed is several orders of magnitude larger than the electrodeposition tank A side. It is the same as the above-mentioned known technology in that it performs auxiliary heating instead of using only the condensation heat of the first pump C, which uses the refrigeration load to be cooled as a heat source, but unlike the above-mentioned known technology as an auxiliary heat source. Without using a boiler, a second heat pump D is provided which uses the condensation heat of both the first heat pump C and the pretreatment tank to heat the pretreatment tank. By using the latent heat loss of the low-temperature steam etc. radiated from the pre-treatment tank B, which corresponds to an approximately intermediate temperature of the temperature inside the processing tank, there is substantially no difference between the first and second heat pumps C and D. It is characterized by being set to have a stage compression configuration.

That is, the present invention focuses on the temperature difference between the pretreatment tank B and the environmental temperature, in other words, by making the environmental temperature substantially function as an intercooler, the low temperature steam radiated from the pretreatment tank B is The latent heat loss of the heat pump is made to correspond to approximately the intermediate temperature of the two-stage compressor, thereby creating a substantially two-stage compression configuration between the first and second heat pumps C and D. .

In addition, E is a hot water tank for storing the condensation heat of both the heat pumps C and D.

"Function" The present invention effectively utilizes the heat loss caused by the temperature difference between the pretreatment tank and the ambient temperature, in other words, the ambient temperature functions as an intercooler to take a two-stage compression structure. Because of this configuration, the driving load of the second heat pump D can be reduced, and the second heat pump D can transfer heat loss on the condenser side of the first heat pump C to the second heat pump without using a special heat source. D is efficiently recovered and the thermal energy cycle is essentially closed, thereby achieving significant energy savings.

In addition, since the electrodeposition solution is cooled only by the first heat pump C, and the pretreatment solution is heated by combining the condensation heat of both heat pumps C and D, there is an imbalance in terms of heat loss. The heat balance between the electrodeposition tank and the pretreatment tank 3 can be easily maintained.

That is, to explain more specifically, since the low-temperature steam is around 40°C, which is higher than the control temperature of the electrodeposition liquid, it can function as an intermediate temperature, and thereby the second heat pump D
The compression load is small, so the power consumption is small, and a large amount of latent heat energy can be obtained at the time of liquefying the vapor, making it possible to create a vehicle that can obtain sufficient condensation heat as auxiliary energy for pretreatment tank B. be.

In addition, in the present invention, by setting the condensation heat of both the heat pumps C and D to be the same, the energy load capacity supplied to the pretreatment tank B is stabilized, thereby reducing the heat load on the pretreatment tank B side. Even when fluctuations occur, it is possible to accurately control the heating temperature.

"Embodiments" Hereinafter, preferred embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, and relative arrangements of the components described in this example are not intended to limit the scope of this invention, but are merely illustrative examples. It's nothing more than that.

FIG. 2 shows a schematic diagram of an electrodeposition coating apparatus according to an embodiment of the present invention. To briefly explain its configuration, 1 is an electrodeposition tank, 2 is a chemical conversion tank, and 3 is a degreasing tank, as is known in the art. The paint liquid or processing liquid stored in these tanks is transferred to heat exchanger 4. ．． It is configured such that it can be cooled or heated by cold water (warm water) stored in the cold water tank 18 or the hot water tank 9 through the pipes 8 and 7, respectively.

Reference numeral 5 designates a first heat pump unit, which is configured to be able to cool the cold water that has exchanged heat with the paint liquid on the side of the evaporator 30 through the heat exchanger 4 on the side of the electrodeposition tank 1, and then returns it to the cold water tank 18. After heating the hot water led from the low temperature tank 10 of the hot water tank 8 on the low temperature side on the condenser 31 side, part of it is led to the high temperature tank 1 of the hot water tank 9, while the other hot water is passed through the heat exchanger 6. After exchanging heat with the chemical liquid through the tank 9, the liquid is introduced into the low temperature tank 10 of the hot water tank 9.

Reference numeral 8 denotes a second heat pump unit that guides the low temperature steam radiated from the chemical conversion tank 2 and the degreasing tank 3 to the evaporator 32 side, and generates condensation heat using the latent heat loss as a heat source.
The hot water introduced from the low temperature tank 10 of the hot water tank 8 is heated and then returned to the high temperature tank 11 of the hot water tank 9.

On the other hand, the degreasing liquid in the degreasing tank 3 is configured to be able to exchange heat with the hot water led from the high temperature tank 11 of the hot water tank 9 via the heat exchanger 7, and the hot water after the heat exchange is returned to the low temperature side hot water tank 9. be done.

Reference numeral 12 denotes an outside air heat exchanger for absorbing load fluctuations in the tanks 8 and 9, which function as a heating tower and a cooling tower, respectively.

Next, the effect based on the actual cooling will be explained.

The paint liquid in the electrodeposition tank 1 is circulated through a pipe line 34 by a pump 13, and is heated by a heat exchanger 4 to exchange heat with the cold water cooled by the evaporator 30 of the first heat pump unit 5 to reach a temperature of 27°C±.
Cooled to 1°C. Alternatively, heat may be exchanged directly between the liquid in the evaporator 30 and the electrodeposition tank 1 without intervening cold water. On the other hand, the hot water heated by the condenser 31 of the heat pump unit 5 is heat exchanged with the chemical liquid in the chemical conversion tank 2 circulating through the pipes 41-44 by the pump 14 in the heat exchanger 6, thereby heating the chemical liquid. The water is maintained at 50°C ± 1'0, and is led to the high temperature tank 11 of the hot water tank 8 through a pipe 42 and stored as hot water at 58°C.

Further, the degreasing liquid in the degreasing tank 3 is circulated through the pipe line 3B by the pump 19, and is heated by the heat exchanger 7 by exchanging heat with the hot water pumped up by the pump 16 from the high temperature tank 11 of the hot water tank 8. The temperature is maintained at ±1°C.

On the other hand, since the processing liquids in the chemical conversion tank 2 and degreasing tank 3 are maintained at 50°C ± 1°C, which is higher than the environmental temperature, they become low-temperature steam and evaporate, and the low-temperature steam is transferred to the intake fan 2.
0.21, the water is sucked into the pipe 52 and introduced as a heat source for the second heat pump unit 8, and the heat pump unit 8 is operated to pump the 53°C hot water from the cold tank 10 of the hot water tank θ by the pump 22 to 58°C. It is heated to °C and led to a high temperature tank 11 of a hot water tank 9. The hot water tank 8 is divided into a high temperature water tank 11 and a low temperature water tank 10 on the return side by a partition.

If the temperature of the hot water in the high temperature tank 11 of the hot water tank 9 rises to 60°C or higher, or if the temperature of the cold water tank 18 rises above the specified temperature (approximately 20°C), the outside air heat exchanger 12 is When the heat exchanger 1 is operated as a cooling tower and the temperature of the cold water drops considerably below the temperature of the cold water in the cold water tank 18,
2 to operate as a heating tower.

"Effects of the Invention" As described above, according to the present invention, thermal efficiency can be significantly improved by effectively combining two heat pump cycles without using an independent auxiliary heat source such as a boiler.

Further, in the present invention, the electrodeposition liquid is cooled only by the first heat pump,
In addition, since the pretreatment liquid is heated by combining the condensation heat of both heat pumps, the heat balance between the electrodeposition tank 1 and the pretreatment tank, which is unbalanced in terms of heat loss, can be easily maintained. In addition, the second heat pump does not require the use of a special heat source. Energy saving can be achieved.

It has various effects such as

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of the present invention, and FIG. 2 is a schematic diagram of an electrodeposition coating apparatus according to an embodiment of the present invention. A, 1: Electrodeposition tank B, 2, 3: Pretreatment tank C95: 1st
Heat pump D, 8: Second heat pump patent applicant 2 Co., Ltd. Maeyo Seisakusho

Claims (1)

[Scope of Claims] 1) In an electrodeposition coating apparatus that effectively utilizes the heat of evaporation and condensation in a heat pump cycle to control the temperature between the pretreatment process tank and the electrodeposition tank, the electrodeposition tank is cooled. The latent heat loss of the low-temperature steam radiated from the pretreatment process tank heated by the condensation heat of the first heat pump whose heat source is the refrigeration load is the second
A heat pump characterized in that the heat pump is used as the heat source of the heat pump, and the pretreatment process tank is heated with the condensation heat of the second heat pump, so that a substantially two-stage compression configuration is created between the first and second heat pumps. 2) The electrodeposition coating apparatus according to claim 1, wherein the condensation heat of both heat pumps is set to the same temperature.