JPH0250966B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is designed to blow hot air from top to bottom and from bottom to top in a furnace when heat treating materials such as long steel pipes or bars, such as annealing or baking. The present invention relates to a hot air alternating jet heating device that enables uniform heat treatment by alternating hot air jets.

In a conventional circulating hot blast furnace, the material to be heated is conveyed sequentially from the charging end to the extraction end on the side wall of the furnace body using a chain conveyor, etc., while an upper duct with a jet nozzle and an upper duct with a jet nozzle are installed at the upper and lower parts of the furnace body. A lower duct with a suction nozzle is provided, and hot air is supplied from an external hot air generating furnace to the upper duct, and hot air after heating the material to be heated is sucked from the lower duct, transferred to an external circulation system, and then heated to the furnace. Inside the main body, hot air was always jetted in one direction from top to bottom to heat the material to be heated.

However, in this conventional circulating hot blast furnace, when heat-treating long steel pipes or bars for the purpose of annealing or baking internal rust-preventing paint, the material to be heated, which is charged horizontally into the furnace, is placed in the upper part. Since the jet nozzle in the duct always sprays water in one direction from top to bottom and heats the material, the material to be heated, such as a long steel pipe, may cause floating phenomena due to thermal warping in the longitudinal direction of the material during heating. This caused problems during conveyance, such as the heated material falling onto the previous material.

The present invention has been made to solve the above-mentioned drawbacks, and its purpose is to alternately switch the hot air for heating the heated material from top to bottom and from bottom to top at predetermined intervals. A hot air alternating jet type that prevents thermal distortion of the material to be heated by heating to even out the temperature distribution inside the furnace, making uniform heat treatment possible and improving heating efficiency. An object of the present invention is to provide a heating device to the general public.

An embodiment of the present invention will be described below with reference to the drawings.

Reference numeral 1 denotes a furnace body, which is of a horizontal feed type and has a material charging port 1a for charging the material to be heated M on one side wall, and a material extraction port 1b for extracting the material from the other side wall. Reference numeral 2 denotes a material transfer device, and in this example, it is an endless chain conveyor 2a that penetrates the inside of the furnace body 1 from the outside of the material loading port 1a and emerges from the material extraction port 1b, and carries one long steel pipe m. It is equipped with a melon 2b for feeding one melon. 3 is an upper duct arranged in parallel along the upper longitudinal direction inside the furnace body 1;
Ejection and suction nozzles 3a facing downward are attached to the lower surface of each of the upper ducts at predetermined intervals. A lower duct is provided, and upwardly directed jetting and suction nozzles 4a are attached at predetermined intervals on each upper surface of the lower duct. Reference numeral 5 denotes an outgoing duct arranged outside the furnace body 1, one of which is connected to the outlet side of the hot air generator 7, and the other connected to the upper outgoing duct 5a midway.
The upper outgoing duct 5a communicates with each end of the upper duct 5, and the lower outgoing duct 5b communicates with each end of the lower duct 4. Reference numeral 6 denotes a return duct disposed outside the furnace body 1, one of which is connected to the inlet side of the hot air generator 7, and the other connected to the outbound duct 5. In this example, the return duct 6 is the upper return duct 6.
A and a lower return duct 6b are branched into two branches, and the upper return duct is connected to the upper outbound duct 5a, and the lower return duct is connected to the lower outbound duct 5b. It is not necessarily necessary to branch into two as in this example. 7
is a hot air generator, and in this example, the flame of a burner 7a is combusted in a combustion chamber 7b. The recirculation blower 8 is connected to the hot air generator 7 via a recirculation duct 9, and blows recovered hot air after heating the material M to be heated into the combustion chamber 7b. In this example, a recirculation blower 8 is connected to the return duct 6. Reference numeral 10 denotes a switching damper provided at a joint where the outgoing duct 5, the incoming duct 6, the upper duct 3, and the lower duct 4 are connected to each other, and the hot air flows between the upper duct 3 and the lower duct 4 from top to bottom. Also, the jets flow alternately from the bottom to the top. In this example, the switching dampers 10 are arranged at four locations: an upper outgoing duct 5a, a lower outgoing duct 5b, an upper return duct 6a, and a lower return duct 6b. The upper and lower dampers 10a, 10b on the outgoing side are connected via a link 14 to levers 11a, 11b fixed to each shaft of the damper and levers 13a, 13b fixed to a vertically installed rod 12. A lever 13b located below the rod 12 is connected to a lever 15a of the control motor 15. On the other hand, both the upper and lower dampers 10c, 10b on the return trip side also have levers 11c, 11d fixed to each shaft of the dampers, and another vertically installed rod 1.
The levers 13c and 13d fixed to the rod 12' are connected via a link 14, and the lever 13e located halfway on the rod 12' is connected to the control motor 1.
5' is connected to the lever 15a. Each control motor 15, 15' is connected to a control unit (not shown) equipped with a timer (not shown), so that the motor 15, 15' is reversed and rotated by a predetermined angle every predetermined time. It's summery.

Therefore, the opening/closing conditions for the switching dampers 10 installed at four locations are such that when the jet of hot air is directed downward from above, the damper 10a in the upper outgoing duct 5a is open, the damper 10b in the lower outgoing duct 5b is closed, and The damper 10d in the lower return duct 6b is set to be open, and the damper 10c in the upper return duct 6a is set to be closed. When the hot air jet is directed upward from below, the damper 10b in the lower outgoing duct 5b is open, the damper 10a in the upper outgoing duct 5a is closed, the damper 10c in the upper return duct 6a is open, and the lower return duct is open. The damper 10d in the damper 6b is set to be closed.

Next, the operating state of the above configuration will be explained.

First, we will discuss the case where the flow of hot air blows out from top to bottom between the upper and lower ducts 3 and 4. The high-temperature hot gas generated by the combustion of the burner 7a of the hot air generator 7 passes through the outgoing duct 5, and passes through the upper This leads to the outgoing duct 5a and the lower outgoing duct 5b. However, the damper 10b in the lower outgoing duct 5b is closed, which blocks the hot air, and the damper 10a in the upper outgoing duct 5a is open, so that hot air flows through it to each of the upper ducts 3. Sent.
Furthermore, since the damper 10c in the upper return duct 6a is closed, the hot air is blocked here, and all the hot gas that has passed through the upper outbound duct 5a flows out to the upper duct 3 side in the furnace main body 1. . Each nozzle 3a of the upper duct 3 serves as a jet nozzle and jets water downward into the furnace body 1, and the chain conveyor 2a
The long steel pipes m that are sent in sequence are heated. Each nozzle 4a of the lower duct 4 acts as a suction nozzle to suck the hot gas after heating the long steel pipe m, and the sucked hot gas is discharged through the lower duct 4 to the lower return duct 6b. .
The damper 10d in the lower return duct 6b is opened, and the lower return duct 5b and the upper return duct 6a are opened.
Since the dampers 10b and 10c in the inner part are closed, the exhaust gas flows to the return duct 6 through the lower return duct 6b, is strongly sucked by the recirculation blower 8, and is transferred to the recirculation duct 9. The air passes through the hot air generator 7 and is circulated. Then, after a predetermined period of time has elapsed, the control motors 15, 1
5' is reversed, and each of the four dampers 10a,
The opening/closing conditions of 10b, 10c, and 10d are completely reversed, and this time hot air blows out from each nozzle 4a of the lower duct 4 in the furnace body 1 and blows onto the long steel pipe m to heat the steel pipe. Hot air flows into upper duct 3
The air is sucked from each nozzle 3a. Thereafter, the hot air is alternately jetted from top to bottom and from bottom to top in the furnace body 1 at predetermined intervals.

FIG. 3 shows another embodiment of the present invention, and the main difference is that only one switching damper 10 is installed at the connection part, and this acts like a three-way valve. The point is that the return duct 6 is connected to the inlet side of the hot air generator 7 without branching into two.
However, when the switching damper 10 is in the position shown by the solid line as shown in the third figure, hot air is blown out from the upper duct 3 toward the lower duct 4, and when the switching damper 10 is in the position shown by the broken line, the operating state is as follows. The hot air is ejected from the lower duct 4 toward the upper duct 3, and the hot air is alternately jetted by changing its vertical direction at predetermined time intervals.

As can be seen from the above description, this invention includes an outgoing duct connected to the outlet side of a hot air generator equipped with a recirculation blower, a return duct connected to the inlet side of the hot air generator, and an upper part of the furnace body. The upper duct and the lower duct, each having a blowout/suction nozzle located at the lower part, are connected to each other, and the hot air flows between the upper and lower ducts from top to bottom and from bottom to top at the connection part. This hot air alternating jet heating device is characterized by being equipped with a switching damper that allows the hot air to heat the material to be heated to flow from top to bottom and from bottom to top for a predetermined period of time. As a result of alternating cycles, the temperature distribution inside the furnace is uniform, and the thermal distortion caused by unidirectional heating (heating from top to bottom) of the material to be heated, which is conventional, can be prevented from occurring. be effective.

Therefore, uniform heat treatment of the material to be heated becomes possible, which not only improves the properties of the product but also improves heating efficiency.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the present invention, FIG. 2 is a perspective view showing a state in which a switching damper and a control motor are connected, and FIG. 3 is a schematic explanatory diagram showing another embodiment. DESCRIPTION OF SYMBOLS 1...Furnace body, 2...Material transfer device, 3...Upper duct, 4...Lower duct, 5...Outbound duct, 6...Return duct, 7...Hot air generator, 8...Recirculation blower, 10...Switching damper.

Claims (1)

[Claims] 1. An outgoing duct connected to the outlet side of a hot air generator equipped with a recirculation blower, a return duct connected to the inlet side of the hot air generator, and jetting and suction nozzles arranged at the upper and lower parts of the furnace body, respectively. The upper duct and the lower duct having the A hot air alternating jet type heating device characterized by: