JPS5837949Y2 - Vertical heat treatment furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vertical strip continuous heat treatment furnace using multiple radiant tube burners.

For continuous heat treatment of strip (metallic steel strip),
There is a vertical heat treatment furnace that uses a large number of radiant tube burners.

In this system, a metal steel strip running in a wavy manner in a furnace is heated by radiant heat from a large number of radiant tube burners, and a conventional device is shown in Fig. 1.

In the figure, 1 is a plenum chamber, 2 is a metal steel strip, 3 is a burner in this example, a radiant tube, 4 is an exhaust gas header, 17 is an exhaust gas duct, 18 is a valve, and 19 is a roll.

The metal steel strip 2 is indirectly heated and heat-treated by radiant heat from a large number of burners 3 provided near the metal steel strip 2 which is guided by each roll 19 and runs in a wave shape.

Each of these burners 3 has a structure as shown in FIG.

In the figure, 5 is a bent tube (radiant tube), 6 is fuel for the pilot frame, air mixed gas header,
7 is a main gas header, 8.9 is a gas cock, 10 is a flexible hose, 4 is an exhaust gas header, 12 is a telescopic pipe, 20 is a pilot gas injection pipe, 21 is a main gas injection pipe, and 22 is a furnace wall.

Arrow 14 indicates the inflow of air, and 15 indicates the flow of combustion exhaust gas.

A mixed gas header 6 supplies a mixed gas to a pilot gas injection pipe 20 via a flexible hose 10 to create a pilot frame for main gas injection.

The main gas, which becomes combustion gas, is supplied from the main gas header 7 to the gas cock 8. The gas is supplied to the main gas injection pipe 21 via the flexible hose 10 and the like.

Air is required for the main gas to burn, and there are two types of air supply methods: a forced type and a suction type.

The push-in type creates positive pressure inside the radiant tube 5, so
If there is a gas leak in the tube, air may enter the furnace.

Therefore, a suction type is generally used, which is carried out by an exhaust gas header 4.

That is, when the exhaust gas header 4 is made to have a negative pressure by a blower (not shown), the combustion exhaust gas in the tube 5 is sucked into the header 4, and surrounding air is accordingly moved to the heat exchange section 11. as shown by the arrow 14. Connecting pipe 13, injection pipe 2 of tube 5
0.21 flows into the tube 5 via a certain inlet end path, thus providing air supply.

As shown in FIG. 1, combustion exhaust gas is sucked into an exhaust gas duct 11 attached to the center of each header, guided to a plenum chamber 1, sucked by a blower (not shown), and discharged to a chimney.

By the way, this combustion exhaust gas has a high temperature of about 700°C to 800°C, and the total length of the exhaust gas header 4 is 1.
It is also 7 to 18 meters long.

Since high-temperature gas tends to rise, the part of the exhaust gas header that connects the burners below the duct 17 has an effective exhaust function, and therefore combustion air flows into the burners below that are connected to the header part. Easy to do.

On the other hand, the part of the header that connects the burners above the duct 17 has an opposite direction of natural movement of high-temperature gas and the suction direction of the gas, making the exhaust operation unsmooth. It becomes difficult for combustion air to flow into the upper burner.

Therefore, even if the air-fuel ratio is planned to be 1, the air-fuel ratio of the lower burner will be 1.3, for example, and that of the upper burner will be 0.9, causing an imbalance in the combustion state of the burners, causing red heat and combustion in the exhaust gas header. This may cause problems such as insufficient main air suction pressure.

Furthermore, when the exhaust gas header becomes 17 to 18 m long, it becomes difficult to absorb thermal expansion due to its structure.

This invention was made with the purpose of dealing with this problem, and is a continuous vertical strip in which a large number of radiation tube burners are arranged vertically, and multiple rows of radiation tube burners are arranged horizontally. In a heat treatment furnace, the header that connects the exhaust parts of each burner in the vertical direction is divided into two parts, one end of an exhaust gas duct is connected to the center of each of the upper and lower headers, and the other end of these ducts is exhausted by a blower. It is characterized by being commonly connected to the plenum chamber.

Next, the present invention will be explained in detail based on examples.

FIG. 3 is a schematic perspective view showing an embodiment of the present invention.

The details of each burner section, etc. are the same as described with reference to FIG. 2 and the like.

The difference is that the header 4 is divided into two parts, an upper part 4a and a lower part 4b, and these central parts are connected to two exhaust gas ducts (17a).
, 17b to the plenum chamber 1.

The combustion method of the burner 3, the exhaust method of combustion exhaust gas, etc. are almost the same as described above, and the exhaust gas flows in the direction of the arrow in the figure.

By the way, in the present invention, the header is divided into two parts and each part is shortened, so the above-mentioned problem of matching or mismatching the natural movement direction of high-temperature gas and the suction direction, that is, the draft problem, is considerably alleviated. Gas flows uniformly to each burner, and each burner burns uniformly.

This draft problem is similar to that of a chimney; the shorter it is, the less the draft difference will be, and vice versa if it is longer.

FIGS. 4 and 5 show specific examples of the present invention.

Of these, FIG. 4 shows the piping part of the wall of the heat treatment furnace 12, and each exhaust gas header 4a, 4b is set as a set of three, and each exhaust gas duct l-17a, 17a', 17a
", 17b, 17b', 17b".

Each of these exhaust gas ducts leads to a plenum chamber 1 shown in FIG.

The reason for dividing the burner in this way is that during heat treatment, the temperature at the furnace outlet of the metal steel strip is measured using a thermometer (not shown), and the combustion of the burner is controlled based on this measured value to bring the steel strip to the desired temperature. This is to make this control easier.

An exhaust gas blower 26 is connected to the blemish chamber 1 via a duct 27 or the like, and the exhaust gas is sucked by the blower and radiated into the atmosphere through a chimney 23.

In the figure, 24 is a damper, and 25 is a telescopic tube.

Further, 42 is a main gas pipe group, which runs parallel to the exhaust gas duct and is guided to each burner.

Further, 41 is a gas and air supply pipe for the pilot frame, and 40 is a mixer thereof.

As explained in detail above, according to the present invention, variations in the air-fuel ratio of the burners are reduced, and each burner performs uniform combustion, so that uniform heat treatment can be applied to the metal steel strip that is the object to be treated. .

[Brief explanation of drawings]

Fig. 1 is a schematic side view of a conventional vertical heat treatment furnace, Fig. 2 is a sectional view showing details of the burner, Fig. 3 is a schematic perspective view showing an embodiment of the present invention, and Figs. 4 and 5 are FIG. 1 is a schematic perspective view showing a specific example of the present invention. In the figure, 1 is a plenum chamber, 3 is a burner, 11 is an exhaust gas header, 16 is a header, and 17 and 17' are exhaust gas ducts.

Claims (1)

[Scope of utility model registration request] In a vertical strip continuous heat treatment furnace in which a large number of radiation tube burners are arranged vertically and multiple burner rows are arranged horizontally, the header that connects the exhaust part of each burner in the vertical direction is divided into two. A vertical heat treatment furnace characterized in that one end of an exhaust gas duct is connected to the center of each of the upper and lower headers, and the other ends of these ducts are commonly connected to a plenum chamber that is exhausted by a blower.