JPH08136053A - Heating equipment of pickling tank - Google Patents

Abstract

PURPOSE: To settle the problem of corrosion of a burner nozzle and others due to acid vapor by connecting a hot air jet nozzle to the lower end of a downcomer pipe of a pickling tank and also by connecting the upper end of the downcomer pipe and a hot air producing device with a flow passage interrupting means interposed between them. CONSTITUTION: A hot air producing device 3 equipped with a gas burner 1 and a pickling tank 4 are installed as separate bodies, and a downcomer pipe 5 of the pickling tank 4 and the hot air producing device 3 are connected with a flow passage interrupting means 8 interposed between them. Thereby flowing of gas between them can be interrupted completely by a distance between them and by the flow passage interrupting means 8 after stoppage of an operation of the gas burner 1 and the possibility that acid vapor flows onto the hot air producing device 3 side from the hot air jet nozzle 6 side and corrodes a gas burner nozzle and others is eliminated. Since an air compressor 2 is used for supply of combustion air to the gas burner 1, besides, hot air can be jetted from small holes 6c of hot air jet nozzles 6 disposed in the bottom part of the pickling tank 4 and thereby the efficiency of acid pickling can be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device for a pickling tank for cleaning metal products and plastic products before painting.

[0002]

2. Description of the Related Art Generally, a cleaning liquid in a pickling tank is preheated to about 60 to 70 ° C. in order to improve a cleaning effect. As a heating device conventionally used for this, as shown in FIG. The type gas heater 21 is immersed in the liquid of the pickling tank 4, the type which uses an electrothermal sheath heater 22 as shown in FIG. 2B, and the steam type heat exchanger 23 which is used as shown in FIG. There are things to use. However, in any case, since it is necessary to use a corrosion-resistant metal for the immersion part, the cost becomes high, and scale or sludge easily adheres to the surfaces of the heater 22 and the heat exchanger 23 due to the acid solution,
Therefore, there is a drawback that the thermal efficiency decreases rapidly,
Further, since the sludge adhered portion is easily heated locally, there is a problem that it is easily damaged by burnout.

[0003]

As a more efficient method of liquid heating than in the prior art, as shown in FIG. 6, the combustion cylinder 25 of the burner 24 is immersed in the liquid, and the combustion is completed in the combustion cylinder 25. There is a submerged combustion type gas burner 24 in which the generated combustion gas passes through the perforated baffle plate 26 to rise in the liquid as fine bubbles. This method has the advantages of high heat efficiency because exhaust gas and liquid directly exchange heat, and there is no concern about sludge, but when this method is used in the pickling tank 4, acidic vapor is generated after the operation is stopped. There is a problem that it goes up inside 25 to corrode burner nozzles and the like, and there is also a problem that the gas burner 24 and the baffle plates 26, 27 take up space so that it becomes an obstacle when putting in and out the object to be cleaned in and out of the tank. . In view of the above-mentioned problems, the present invention has an object to solve the problem of corrosion of a burner nozzle or the like due to acid vapor in a method of directly exchanging heat with combustion exhaust gas.

[0004]

As shown in FIGS. 1 (a) and 1 (b), a pickling tank heating apparatus according to the present invention comprises a gas burner 1 and an air compressor 2 for supplying combustion air to the gas burner 1. The provided hot air generator 3 is installed in the vicinity of the pickling tank 4 and at a slight distance from the pickling tank 4, and is provided at the lower end of the hanging pipe 5 vertically extending along the inner wall of the pickling tank 4. A flow path blocking means 8 for preventing the backflow of the acidic vapor when the hot air is stopped is provided in the middle of the connection pipe 7 that connects the hot air jet nozzle 6 and the upper end of the hanging pipe 5 and the hot air generator 3. For example, a manual butterfly valve) is installed.

[0005]

According to the structure of the present invention, the hot air generator 3 provided with the gas burner 1 and the pickling tank 4 are installed as separate bodies, and the hanging pipe 5 of the pickling tank 4 and the hot air generating apparatus 3 are provided in the flow path. Since the gas burner 1 is connected through the shutoff means 8, the gas flow between the two can be completely shut off by the distance between the gas burner 1 and the flow path shutoff means 8 after the operation of the gas burner 1 is stopped. There is no fear that acidic vapor will flow into the hot air generator 3 side and corrode the gas burner nozzle, etc.
Further, since the air compressor 2 is used to supply the combustion air to the gas burner 1, the hot air can be jetted from the pores 6a of the hot air jet nozzle 6 arranged at the bottom of the pickling tank 4 against the water pressure. As a result, the upper opening of the pickling tank 4 can be widely opened for taking in and out the object to be cleaned, and the bubbles can be discharged at a deep place to enhance the heat exchange efficiency with the liquid, and the liquid bubbles The pickling efficiency can be improved by stirring the.

[0006]

1 (a) shows an embodiment of a hot air generator 3 used in a pickling tank heating apparatus according to the present invention. The hot air generator 3 directly burns combustion exhaust gas as hot air. In addition to a gas burner 1 and an air compressor 2 for supplying a high-pressure premixed gas to the gas burner 1, a control valve for air and fuel, a premixer, a blower for supplying secondary air, etc. Is provided. The hot air generator 3 configured in this way is installed separately from the pickling tank 4 and at a slight interval between the two. Also pickling tank 4
As shown in FIG. 2B, a hanging pipe 5 is vertically installed along the inner wall, and a header 6 a is provided at the lower end of the hanging pipe 5.
The hot air jet nozzle 6 having the pores 6c arranged in line in the pipe 6b is connected through the pipe 6b, and the upper end of the hanging pipe 5 and the hot air generator 3 are connected by the connection pipe 7. A manual butterfly shutoff valve is provided as means 8 for shutting off the flow path in the middle of the process.

In this embodiment, the cleaning liquid heating temperature is 60 to 7
The hot air blowing temperature is set to 800 to 1000 ° C., the depth of the pickling tank 4 is about 1 m, and the hot air maximum pressure is about 3,000.
Although it is 0 mmAq, the air pressure of the compressor is 6,000 mmAq, the connecting pipe 7 is made of stainless steel, and the hanging pipe 5 and the hot air jet nozzle 6 are easily used as consumables. It is replaceable and uses inexpensive materials. In addition, a manual shutoff valve is used as the flow path shutoff means 8, and the hot air generator 3
Immediately after the operation is stopped, the flow path is shut off by the shutoff valve 8 to prevent the acid vapor from flowing back through the heated pipes 5, 6 and 7 from the pickling line tank 4.

Since a relatively low pressure exhaust gas of about 0.3 atm passes through the connecting pipe 7, airtightness is not required so much as a flow path blocking means, and therefore, as shown in FIGS. 2 to 4. Even a relatively simple structure can sufficiently achieve the purpose. In the embodiment shown in FIG. 2, the ends of both connecting pipes 7a and 7b facing each other with a slight distance are attached and detached by a sliding sleeve 9.
When removing the sleeve 9 from the high temperature connecting pipe 7b, the sleeve 9 can be easily slid by hitting the flange portion 9a with a hammer. In addition, the embodiment of FIG.
The connection pipe 7 is provided with an air vent 10, which is opened and closed by a sliding sleeve 9. Further, in the embodiment of FIG. 4, the flow path blocking means 8 is provided with a case 11 and a flap plate 12.
It is configured such that the air vent hole 10 on one side of the connecting pipe 7b is opened and at the same time the end portion of the other connecting pipe 7a is closed, and one piece of the flap plate 12 closes the air vent hole 10. At times, hot air passes through the ventilation holes 13 provided in the other piece. Reference numeral 14 is a handle that is also used for hanging.

[0009]

According to the present invention, as described above, the hot air generator 3 having the gas burner 1 and the pickling tank 4 are separately provided, and the hanging pipe 5 and the hot air generator 3 of the pickling tank 4 are provided. Since they are connected via the flow path blocking means 7, the flow of gas between them can be completely blocked by the flow path blocking means 8 after the operation of the gas burner 1 is stopped. Since there is no risk that the steam of the above will flow into the hot air generator 3 side and corrode the gas burner nozzle etc., there is an advantage that a highly durable device can be provided, and an air compressor for supplying combustion air to the gas burner 1 is provided. Since 2 is used, hot air can be jetted from the pores of the hot air jet nozzle 6 arranged at the bottom of the pickling tank 4 against water pressure, whereby the top opening of the pickling tank 4 is cleaned. Putting things in and out Therefore, there is an advantage that the heat exchange efficiency with the liquid can be improved by releasing the bubbles from a deep place, and the liquid can be stirred by the bubbles to improve the pickling efficiency. Further, there is an advantage that the amount of water evaporation is increased by agitation of the bubbles, and the liquid concentration can be prevented from lowering due to the introduction of water from the hot water washing process.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, in which (a) is a side view and (b) is a partially cutaway perspective view.

FIG. 2 is a vertical sectional view showing an embodiment of the flow path blocking device used in the present invention.

FIG. 3 is a vertical perspective view showing another embodiment of the above.

[Fig. 4] Fig. 4 shows still another embodiment of the above, in which (a) is a perspective view and (b) is a longitudinal sectional view.

5A, 5B and 5C are schematic vertical sectional views showing various conventional examples.

FIG. 6 is a vertical cross-sectional view showing another conventional example.

[Explanation of symbols]

 1 gas burner 2 air compressor 3 hot air generator 4 pickling tank 5 hanging pipe 6 hot air jet nozzle 7 connecting pipe 8 flow path blocking means

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Satoshi Minami 4-1-2, Hiranocho, Chuo-ku, Osaka City Osaka Gas Co., Ltd. (72) Inventor Masao Kawamoto, 8-chome, Onoue-cho, Naka-ku, Yokohama Katsura Seiki Co., Ltd.

Claims (1)

[Claims] 1. A hot air generator comprising a gas burner and an air compressor for supplying combustion air to the gas burner is installed near the pickling tank and at a slight distance from the pickling tank. The hot air jet nozzle is connected to the lower end of the hanging pipe vertically extending along the inner wall of the pipe, and the flow path blocking means is interposed in the middle of the pipe connecting the upper end of the hanging pipe and the hot air generator. Pickling tank heating device.