JPH0322271Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a galvaneal furnace for producing alloyed galvanized steel strip, which has a uniform temperature distribution in the width direction of the furnace and reduces fuel costs.

(Prior art) Alloyed hot-dip galvanized steel strips are manufactured by heating the steel strip after plating to alloy the plated layer, but a vertical galvanized furnace is used for heating. ing.

This galvaneal furnace has openings at the bottom and top of the furnace, and the galvanized steel strip is moved inside the furnace wall from the bottom of the furnace body, which has a wind tunnel shape, to the top of the furnace. A burner (usually a gas burner) is provided to heat the hot-dip galvanized steel strip.

(Problem that the invention aims to solve) However, if an opening is provided at the bottom of the furnace body, which is shaped like a wind tunnel, the inside will become hot, and a large amount of air will be sucked in from there during operation. It was hot. As a result, the temperature inside the furnace was lowered by this air, and enough heat was released from the top of the furnace to still produce alloying, resulting in a low thermal efficiency of the furnace. Also, due to the difference in draft pressure, the temperature distribution in the width direction of the furnace becomes higher in the center, and the center of the alloyed hot-dip galvanized steel strip is alloyed more than the edges.
There were differences in the degree of alloying depending on the width direction.

Conventionally, in order to reduce the influence of such openings, doors were installed at the openings between the bottom and top of the furnace, and the area of the opening was made as narrow as possible. Pass lines etc. are not always constant, so if you make them too narrow,
Touching the door would cause scratches on the plating layer. Therefore, there is a limit to how narrow the area of the opening can be made.

(Means for solving the problems) In view of the above-mentioned problems with conventional galvanil furnaces, the present invention is an alloying method that has good furnace thermal efficiency and a uniform degree of alloying in the width direction. This provides a galvanized furnace capable of manufacturing hot-dip galvanized steel strips. A gas injection nozzle facing diagonally downward is arranged inside the upper part of the furnace, and the high-temperature combustion gas of the furnace is injected either singly or with air through the nozzle. By injecting the gas at the same time and sealing the top of the furnace with gas, air intake from the opening at the bottom of the furnace is reduced. That is, the present invention places a gas injection nozzle facing obliquely downward inside the upper part of the furnace, and connects the nozzle to the exhaust side of a blower whose intake side is connected to the high-temperature combustion gas section of the furnace or between the high-temperature combustion gas section and the atmosphere. The high-temperature combustion gas from the furnace is circulated through the upper part of the furnace, and the gas is sealed.

In this invention, it is preferable to connect the intake side of the blower only to the high-temperature combustion gas section of the furnace in terms of the thermal efficiency of the furnace and the temperature distribution in the width direction, but using high-temperature combustion gas alone may have a negative effect on the life of the blower and nozzle. be. In such cases, the intake side is connected to the hot combustion gas section of the furnace and to the atmosphere. In this case, the air mixing ratio may be up to 90% by volume.

The angle at which the gas injection nozzle is directed diagonally downward is 10 to 80 degrees, preferably 45 degrees with respect to the furnace wall.

The galvanil furnace of this invention can not only be used to alloy the galvanized steel strip, but also other galvanized steel strips (such as electroplated steel strips and vapor-deposited steel strips).
It can also be used for plating layer alloying.

Next, the present invention will be explained with reference to examples.

(Example) Figure 1 shows the part where the galvanil furnace of continuous hot-dip galvanizing equipment is installed.
After being plated in a galvanizing bath 2, it is pulled up from the galvanizing bath 2, and immediately after being pulled up, excess zinc adhering to it is removed by a gas wiping nozzle 3, resulting in a hot-dip galvanized steel strip 4. . After that, this hot-dip galvanized steel strip 4 enters a galvanic furnace 5,
The plating layer is alloyed. Like a conventional furnace, the galvanil furnace 5 has openings 6 at the bottom and top of the furnace, creating a wind tunnel shape inside, and a plurality of gas burners 7 facing each other on the furnace wall. There is. Inside the upper part of the furnace, a gas injection nozzle 8, which is a feature of the present invention, is embedded in the furnace wall. The gas injection nozzles 8 may be continuous slit-like ones or independent ones arranged in a straight line, but the tips thereof face diagonally downward and the bases communicate with the distribution pipe 9.

Figure 2 shows the gas injection nozzle 8 and the galvanic furnace 5.
This figure shows a circuit for circulating combustion gas, and the combustion gas is circulated by a blower 10. That is, an intake pipe 11 is connected to the intake side of the blower 10, and a combustion gas pipe 12 whose end is located in the high temperature combustion gas section of the galvaneal furnace 5 and an air pipe 13 whose end is located in the air are connected to the intake pipe 11. and a flow rate regulating valve 14 is attached to these, and an exhaust pipe 15 is connected to the exhaust side of the blower 10 and connected to the distribution pipe 9 by branching in the middle. And the exhaust pipe 15 has a sensor 16 for measuring gas temperature.
and a gas pressure measuring sensor 17 are attached, and these sensors are connected to the flow rate regulating valve 14 via a control device 18 so that the gas temperature and pressure in the exhaust pipe 15 are automatically controlled. Also exhaust pipe 15
A damper 19 for rectification and a pressure gauge 20 are attached to the branching part of the pressure gauge 20 so that the final pressure can be determined.

(Function) When the blower 10 is operated in the galvanic furnace 5 configured as described above, high-temperature combustion gas and air are sucked in from the combustion gas pipe 12 and the air pipe 13, respectively, and enter the intake pipe 11. . At this time, if the temperature and pressure of the exhaust pipe 15 are set to be constant using the control device 18, the flow rate adjustment valve 14 of the combustion gas pipe 12 and the flow rate adjustment valve 14 of the air pipe 13 are adjusted, and the exhaust pipe 15 The temperature and pressure of can be kept constant. Therefore, since high-temperature combustion gas is always injected diagonally downward from the gas injection nozzle 8, the upper part of the galvanic furnace 5 is sealed with gas.
Air suction from the lower opening of the galvanic furnace 5 is prevented.

(Effects) As described above, the galvanil furnace of the present invention has a gas injection nozzle facing diagonally downward arranged in the upper part of the furnace, circulates and injects high temperature combustion gas from there, and seals the upper part with gas. So,
Air intake from the lower opening is eliminated, the combustion efficiency of the furnace is improved, and the temperature distribution in the width direction of the furnace is also made uniform, so that the degree of alloying of the plated steel strip in the width direction can be made uniform. In fact, when the degree of improvement in thermal efficiency was measured in terms of fuel consumption during the production of alloyed hot-dip galvanized steel strip, it was found to have improved by 15 to 20%.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the part of continuous hot-dip galvanizing equipment in which the galvaneal furnace of the present invention is installed, and Figure 2 is a sectional view showing the part of the continuous hot-dip galvanizing equipment where the galvanil furnace of the present invention is installed. FIG. 2 is a circuit diagram showing a circuit for circulating gas. 1... Steel strip, 2... Galvanizing bath, 3... Gas wiping nozzle, 4... Hot-dip galvanized steel strip,
5... Galvanil furnace, 6... Opening, 7... Gas burner, 8... Gas injection nozzle, 9... Distribution pipe, 10... Blower, 11... Intake pipe, 12...
... Combustion gas pipe, 13 ... Air pipe, 14 ... Flow rate adjustment valve, 15 ... Exhaust pipe, 16 ... Gas temperature measurement sensor, 17 ... Gas pressure measurement sensor, 1
8... Control device, 19... Rectification damper, 20
...Pressure gauge.

Claims (1)

[Scope of utility model registration request] In a vertical galvanizing furnace that heats a plated steel plate to alloy the plated layer, a gas injection nozzle facing diagonally downward is placed inside the upper part of the furnace, and the intake side of the nozzle is connected to the high temperature combustion gas section of the furnace. Or a galvaneal furnace characterized in that it is connected to the exhaust side of a blower that is connected to the high-temperature combustion gas section and the atmosphere.