JPH0585819B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heating device for a liquid bath in metal surface treatment equipment.

[Conventional technology]

Metal surface treatment processes such as degreasing, film formation,
In processes such as hot water washing, painting, and water resistance treatment, it is necessary to heat a tank containing processing liquid to a predetermined temperature. When heating such a liquid tank, conventional methods include placing a heating coil or heating panel inside the liquid tank and supplying the heating medium from a hot water boiler or steam boiler, or heating the liquid tank directly from the outer periphery. An open flame method was used.

[Problem that the invention seeks to solve]

However, when heating a liquid tank using the above-mentioned heating means, limescale and sludge adhere to the heat exchangers such as heating coils and heating panels, and the bottom of the tank, so that the heat transfer effect is limited for a short period of time. It will drop significantly over time, and the fuel ratio will deteriorate. In addition, maintenance is extremely troublesome and costly as it is necessary to frequently remove scale and sludge, and the operation rate must be interrupted due to the removal of scale and sludge, which unnecessarily reduces the operating rate. There was a problem.

[Means for solving problems]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heating device for a liquid tank that can solve the above-mentioned problems and can reliably prevent a decrease in heat transfer efficiency without causing lime scale or sludge to adhere to the heater or the bottom of the tank.

In order to achieve this objective, the present invention changes the conventional idea, and instead of directly heating the liquid in a liquid tank,
A heating means is installed in the spray chamber leading to the liquid tank, and a circulation circuit is adopted in which the liquid led from the liquid tank is sprayed, brought into contact with the heating means, and then flows into the liquid tank to prevent limescale and sludge from adhering. The liquid is then heated.

In other words, the present invention is characterized in that a spray chamber is provided above the liquid tank, a conveyor for transporting the object W to be treated is provided above the spray chamber, and a sprayer for spraying the liquid onto the object W is provided in the spray chamber. In metal surface treatment equipment in which a nozzle mechanism is installed and connected to a liquid tank via circulation piping, a heat medium is supplied from an external heat medium supply means into the spray chamber at a level above the liquid level of the liquid tank. A metal surface treatment equipment characterized in that a receiving heat exchanger is installed horizontally, and the working liquid sprayed onto the workpiece from a spray nozzle mechanism is brought into contact with the heat exchanger and flows down into a liquid tank. Liquid tank heating device.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the liquid tank heating device according to the present invention, and shows a case where the device is applied to equipment for spraying a treatment liquid onto an object to be treated. In the drawing,
Reference numeral 1 denotes a liquid tank, which accommodates cleaning liquids such as chemical conversion treatment agents, degreasing agents, hot water washing liquids, and water resistance treatment agents. A spray chamber 2 is provided at the upper part of the liquid tank 1, and communicates with the liquid tank 1 through at least a portion such as the lower part. 3 is a spray nozzle mechanism arranged in the spray chamber 2.

Reference numeral 5 denotes a circulation pipe, which is connected at one end to the liquid tank and at the other end to the spray nozzle mechanism 3, with a pump P interposed and connected in the middle.

Reference numeral 6 denotes a heating means for the liquid, more specifically a heat exchange section, through which a heat medium such as hot water, steam, or hot air flows. In the present invention, the heat exchanger 6 is disposed in a spray chamber whose level is higher than the liquid level in the liquid tank 1, so that the liquid sprayed from the spray nozzle mechanism 3 comes into contact with the heat exchanger 6. The heat exchanger 6 is connected to a heat medium supply means 7, such as a boiler.

The heat exchanger 6 is generally an inverted bent pipe, a lattice type,
It is suitable to have a structure that allows the liquid to pass through, such as a grating shape.

Figures 2 to 4 show an embodiment in which the present invention is applied to spray-type pretreatment equipment for metal products, which includes a chemical liquid zone 4A and a plurality of cleaning zones 4B, 4C, 4D, and 4E following this. It is made up of
Each of these zones has liquid tanks 1a, 1b, 1c,
1d and 1e are provided, and a tunnel-shaped spray chamber 2 is provided above the liquid tank. A conveyor 8 is installed above the spray chamber 2, and the workpiece W is transported at a predetermined speed.

Circulation piping 5a is provided in the liquid tanks 1a to 1e of each zone.
5e are provided, and the pumps P ₁ to _{P 5} supply the liquid to the spray nozzle mechanisms 3a to 3e in the spray chamber.

A heat exchanger 6 is disposed horizontally in the lower area of the spray chamber above the liquid tank of the chemical liquid zone 4A.
One end is connected to a heat medium supply means 7 such as a hot water boiler.

FIG. 5 further shows another embodiment of the present invention, in which circulation piping 5a to 5 of cleaning zones 4B to 4E are shown.
Bypass pipes 9b to 9e are provided in e, and each of these bypass pipes extends to the outlet of the front stage zone (boundary zone for liquid draining), and spray nozzles 10b to 10e are provided at the tip. Further, a fresh water pipe 11 is led to the outlet of the final zone, and a replenishment spray nozzle 12 sprays fresh water.

Control valves 13b to 1, such as electromagnetic valves, are provided in each of the bypass pipes 9b to 9e, respectively.
3e, the control valve 13b in the first cleaning zone 4B is operated by a level switch 14a provided in the liquid tank 1a of the chemical zone 4A, and the control valve 13c in the second cleaning zone 4C is operated in the first cleaning zone 4B. It is operated by a level switch 14b provided in the liquid tank 1b of zone 4B, and the bypass pipe 9 is operated in the same manner.
d is the level switch 14c of the liquid tank 1c in the previous stage;
The bypass pipes 9e are respectively connected to the level switches 14d of the preceding medicine tank 1d. In order to prevent excess water from forming in the new water pipe 11 of the final cleaning zone 4E, water level adjustment valves 15, 15 are operated by the high water level and low water level level switches 14e, 14e' provided in the liquid tank 1e. ' is provided.
With the above configuration, the amount of washing water sent to the spray chamber of each washing zone and the amount of washing water sent to the preceding spray room are automatically controlled to be in the range of 100 to (1 to 0.1), thereby improving the water washing efficiency. and minimize the amount of liquid brought in from the front zone.

On the other hand, a heat exchanger 6 is installed horizontally in the lower area of the spray chamber of the chemical zone 4A, and one end of the heat exchanger 6 is led to an external heat medium supply means 7.

A hot air blowing section 16 having an arbitrary structure such as a slit shape is provided at the entrance of the chemical liquid zone 4A, so that a high temperature gas curtain is formed.
A waste heat pipe 18 led from other heating equipment 17 such as a baking furnace and a drying furnace is connected to this hot air blowing section 16. If necessary, waste heat from a heating source 17' of the heat medium supply means 7 may be introduced into the waste heat pipe 18 as shown.

Further, a suction/exhaust section 19 is provided near the chemical zone 4A, preferably at an intermediate position between the chemical zone 4A and the first cleaning zone 4B, and the suction/exhaust section 19 is an exhaust duct equipped with a gas-liquid separator 20 and a load fan 21. 22.

It should be noted that the present invention is of course applicable to the so-called single-tank type, and in the embodiment shown in FIG. 1, the same hot air blowing section 16 and suction/exhaust structure as in the embodiment shown in FIG. Of course it is possible.

[Effect]

Since the present invention has the above-described configuration, during operation, the heat medium supply means 7 is connected to the heat exchanger 6.
While supplying a heat medium to the spray nozzle mechanism 3, the pump P is driven to take out the liquid from the liquid tank 1 and supply it to the spray nozzle mechanism 3.

The atmospheric temperature in the spray chamber 2 is raised by the heat exchanger 6, and in this state, the liquid is jetted from the spray nozzle mechanism 3 into the spray chamber 2 and falls in a shower shape. In the embodiment shown in FIG. 1, a heat exchanger 6 is disposed in this falling area, so that the shower-like dispersed liquid comes into contact with the heat exchanger 6, is heated, and flows into the liquid tank 1. By repeating this operation, the liquid in the liquid tank is heated. In addition, when the hot air blowing part 16 is provided in the spray chamber 2, the liquid is heated even more rapidly.

Once the temperature of the solution has risen to a certain level in this way, the object to be treated W is loaded by means such as a conveyor, and the object to be treated W is transported through the spray chamber 2 and used by the spray nozzle mechanism 3. Liquid is sprayed.

The sprayed liquid always comes into contact with the heat exchanger 6 and is heated before flowing down into the liquid tank 1. On the other hand, since there is no still water around the heat exchanger 6 and the sprayed liquid comes into contact with it, Limescale and sludge are constantly physically washed away, making it difficult for limescale and sludge to adhere even after long-term operation. As a result, stable heat transfer efficiency is maintained, energy is saved, and the complicated work of removing sludge is reduced, greatly improving workability and operating costs.

Further, by providing the heat exchanger 6 in the spray chamber 2, the atmospheric temperature of the spray chamber increases as described above, and therefore the amount of water saturation in the air increases.
Therefore, the liquid is turned into a mist by the nozzle, and the evaporation rate becomes faster. Therefore, if the present invention is applied to the evaporation means, efficient heating of the liquid tank and effective evaporation of excess water can be achieved at the same time.

When applied to a continuous surface treatment equipment as shown in Fig. 5, the object to be treated is always cleaned by the cleaning liquid from the next stage on the outlet side, and hot air is introduced from the inlet side and the spray chamber of chemical zone 4A is used. The arrangement of the heat exchanger 6 in the chemical zone and the suction exhaust from the chemical zone outlet side significantly reduce the drop in chemical temperature in the chemical zone, and extremely effective water evaporation is carried out, thereby producing excess water. Surface treatment can be performed easily and with high water washing efficiency.

〔Effect of the invention〕

According to the present invention described above, the spray chamber 2 is provided above the liquid tank 1, the conveyor 8 for transporting the object W to be processed is provided above the spray chamber 2, and the spray chamber 2 is provided with a spray chamber 2 for transferring the object W to be processed. In a metal surface treatment equipment of the type in which a spray nozzle mechanism 3 for spraying is arranged and connected to a liquid tank 1 through a circulation piping 5, an external A heat exchanger 6 that receives the heat medium from the heat medium supply means 7 is installed horizontally, and the liquid sprayed onto the workpiece W from the spray nozzle mechanism 3 is brought into contact with the heat exchanger 6 and transferred to the liquid tank 1. Since the processing liquid is made to flow down, when the processing liquid for treating the workpiece W is ejected from the spray nozzle mechanism 3, the spray liquid is supplied with heat medium from the external heat medium supply means 7 before falling into the liquid tank 1. It comes into contact with the heat exchanger 6 receiving the supply, is heated, and is returned to the liquid tank 1. Therefore, even if the machining liquid has a property that sludge tends to form, the sludge is constantly washed off from the heat exchanger 6.
Therefore, due to its simple structure, it is possible to obtain good heat transfer efficiency without causing limescale or sludge to stick to the heating means or the bottom of the tank.It also reduces the complicated work associated with sticking of sludge, and simplifies maintenance. Excellent effects such as cost reduction can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing an embodiment of a liquid bath heating device according to the present invention, and FIG. 2 is a plan view showing an embodiment in which the present invention is applied to a silver group surface treatment line.
FIG. 3 is a sectional view taken along the line of FIG. 2, FIG. 4 is a partially cutaway side view thereof, and FIG. 5 is a sectional view showing another embodiment in which the present invention is applied to a metal surface treatment line. be. DESCRIPTION OF SYMBOLS 1... Liquid tank, 2... Spray room, 3... Spray nozzle mechanism, 5... Circulation piping, 6... Heat exchanger, 7... Heat medium supply means, W... Treated object.

Claims (1)

[Claims] 1 A spray chamber 2 is provided in the upper part of the liquid tank 1, a conveyor 8 is provided in the upper part of the spray chamber 2 to transfer the object W to be processed, and a spray nozzle mechanism 3 is provided in the spray chamber 2 to spray the liquid onto the object W to be processed. In this metal surface treatment equipment, heat is supplied from an external heat medium supply means 7 to the spray chamber 2 at a level above the liquid level of the liquid tank 1. A heat exchanger 6 that receives a medium supply is installed horizontally, and the liquid sprayed from the spray nozzle mechanism 3 onto the object W to be treated is brought into contact with the heat exchanger 6 and flows down into the liquid tank 1. A heating device for a liquid tank in metal surface treatment equipment, characterized by: