JPS60141820A - Heating device by alternate ejection of hot air - Google Patents

Abstract

PURPOSE:To heat uniformly many long-sized steel pipes, etc. and to prevent thermal warpage in the stage of subjecting the stel pipes to a heating treatment in a heating furnace by ejecting alternately hot air for heating from above and below. CONSTITUTION:Long-sized materials (m) to be heated such as many steel pipes and steel bars are passed by an endless chain conveyor 2a through the inside of a heating furnace. Plural upper ducts 3 and lower ducts 4 are disposed in the furnace 1. A going duct 5 having an upper going duct 5a and a lower going duct 5b is connected to a hot air generator 7. A blower 8 for circulation and a duct 9 for recirculation are connected to a returning duct 6. The hot air from the generator 7 enters first the duct 5a, then the upper ducts 3. The hot air is ejected from the many nozzles 3a to heat the steel pipes (m) and thereafter the hot air flows through the nozzles 4a of the lower ducts 4 and the duct 5a into the blower 8 and is again fed to the generator 7. The hot air is then ejected upward from below reverse from the above-mentioned method by changing over of the dampers in the respective ducts and such ejection is alternately changed over, by which the pipes (m) are uniformly heated.

Description

[Detailed description of the invention] Hot air is jetted alternately from the bottom to the bottom and from the bottom to the top in a furnace when performing heat treatment such as annealing and baking of materials to achieve uniform heat treatment. This invention relates to an alternating jet heating device.

1- 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 jet nozzles are installed at the top and bottom of the furnace body, respectively. A duct and a lower duct with a suction nozzle are installed,
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 and transferred to the external circulation system, so that the hot air is constantly kept inside the furnace body.
The material to be heated was heated by jetting it in one direction from the bottom to the bottom.

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. Because the jet nozzle in the duct always sprays air in one direction downwards, the material to be heated, such as a long steel pipe, may float up due to thermal warping in the longitudinal direction of the material during heating. This caused problems during conveyance, such as the heated material falling over onto the previous material.

2 - The present invention has been made to eliminate the above-mentioned drawbacks, and
The purpose is to produce hot air that heats the material being heated.
Heating is performed from the top to the bottom and from the bottom of the trench to the top at predetermined time intervals to even out the temperature distribution inside the furnace. The object of the present invention is to generally provide a hot air alternating jet type heating device which is capable of heat treatment and which is designed to improve heating efficiency.

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

(2) is the furnace body, with a material charging port 1a for charging the material to be heated M on one side wall and a material extraction port 1bi for extracting the material on the other side.
The horizontal feed type equipped with each type is shown. Reference numeral 2 denotes a material transfer device, and in this example, it shows an endless chain conveyor 2a that penetrates the inside of the furnace body 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. Reference numeral 3 denotes upper ducts arranged in parallel along the longitudinal direction of the upper part of the furnace body 1, and on the lower surface of each of the upper ducts, jet and suction nozzles; 3a directed downward are attached at predetermined intervals. There is. 4 is a lower duct arranged in parallel along the lower longitudinal direction of the furnace body, facing the upper duct, and on the upper surface of each of the lower ducts are jetting and suction units directed upward at predetermined intervals. A nozzle 4a is attached. 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 is connected to the upper outgoing duct 5a and the lower outgoing duct 5b. The upper outgoing duct 5a branches into -
1 partially communicates with each end of the duct 5, and a lower outgoing duct 51
) communicate with each end of the lower duct 4. Reference numeral 6 denotes a return duct disposed outside the furnace main body; one of the return ducts is connected to the input side of the hot air generator 70, and the other is connected to the outbound duct 5. In this example, the return duct 6 is bifurcated into an upper return duct 6a and a lower return duct 6b.
Although a case is shown in which the L section return duct is connected to the upper outbound duct 5a and the lower return duct is connected to the lower outbound duct 5b, the return duct 6 is not necessarily bifurcated as in this example. There is no need to branch out. 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 9f, and blows recovered hot air after heating the material M' (z) into the combustion chamber 7b. A recirculation pro-arry is connected to the return duct 6. Reference numeral 10 denotes a switching damper provided at a joint where the outbound duct 5, the return duct 6, the upper duct 3, and the lower duct 4 are connected to each other. The hot air flows between the lower ducts 4 from top to bottom,
Also, the jets are arranged to flow alternately from the bottom to the first one. In this example, the switching damper 10, upper outgoing duct 5a + lower outgoing duct) 5bt, upper return duct 6a and lower return duct)
It is arranged in four places of 6b.

Of these, both the upper and lower dampers 10a, 10b on the outbound side have levers 11a, 11) fixed to each shaft of the damper,
Lever 13 a + 1 fixed to vertically installed rod 12
3b are connected to each other via a link 14, and the lever 13b located below the rod 5-12 is connected to the lever 15a of the control motor 5. - Both the upper and lower dampers 10C, ]Ob on the inferior road side are also levers 110 fixed to each shaft of the dampers. lld and levers 13 c + 13 d fixed to another vertically installed rod 12' are linked together 14
The lever 13e located in the middle of the rod 12' is connected to the lever 15a of the control motor 15'.
Connect to. 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 at predetermined intervals. It has become.

However, the opening/closing conditions for the switching dungeons 10 installed at four locations are as follows: When the jet of hot air is directed downward from the top,
Damper 10a in 6b is open, damper 10a in upper return duct 6a is open, damper 10a in upper return duct 6a is open, damper 10a in lower return duct 5b is closed, and lower return damper is open
Set so that C is closed. When the hot air jet is directed upward from below, the damper 101 in the lower outgoing damper 5b
) is open, the damper in the two-part outgoing duct 5a]Oa is closed, and the damper in the upper rear duct 6a]Oc is open, and the damper in the lower return duct 6b is closed. Set it as follows.

Next, the operating state of the configuration described in -1- will be explained.

To describe the case where the flow of hot air blows out downward between the upper and lower decks 1-3 and 4 without being separated, 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, Upper outgoing duct 5a and lower outgoing duct 1
This brings us to 5b. However, the damper 10b in the lower outgoing dan) 5b is closed, which blocks the hot air, and the damper 10a in the outgoing dan) 5a is open, so the hot air passes through this and enters the upper duct. 3 each.

Since the damper 10c in 6a is closed, the hot air is blocked and the upper outgoing damper is closed.
All the hot gas that has passed through 5a is transferred to the upper duct 3 in the furnace main body l.
It flows out to the side. Then, each nozzle 3a of the upper duct 3 becomes a spout nozzle and spouts out downwards inside the furnace body.
The long steel pipes m that are sequentially sent by the chain conveyor 2a 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 lOd in the lower return duct) 6b is opened, and each damper 10b in the lower outbound duct 5b and the upper return duct 6a
+ ], Oc is closed, so the exhaust gas flows through the lower return duct 6b to the return duct 6, is strongly sucked by the recirculation blower 8, and then passes through the recirculation duct 9. The hot air then goes to the hot air generator 7 and is circulated. After a predetermined period of time has elapsed, the control motor 15.1
5' is reversed, and each of the four dampers toa, 1
0b.

The opening/closing conditions of ]Oc and ]Od are completely reversed, and hot air is now ejected from each nozzle 4a of the lower duct 4 in the furnace body 1 and blown onto the long steel pipe m to heat the steel pipe. Hot air is sucked from each nozzle 3a of the upper duct 3. 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 in the connecting part, and this acts as 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 blows out from the lower duct 4 toward the upper duct 3, and changes its vertical direction at predetermined time intervals to create alternating jets.
Become.

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 a furnace main body. When the upper duct and the lower duct, which have blowout and suction nozzles arranged at the upper and lower parts respectively, are connected to each other, hot air flows between the upper and lower ducts from the top to the bottom and from the bottom at the connection part. up 9
- Since it is a hot air alternating jet type heating device characterized by being equipped with a switching damper that generates an alternating jet flow, the hot air for heating the heated monthly air is directed downward from -L and from 1 point below to above. As a result of alternating switching at predetermined intervals, the temperature distribution inside the furnace becomes uniform, and the material to be heated can be heated in one direction ("
This has the excellent effect of preventing the occurrence of thermal distortion caused by heating from the top down.

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

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the invention. FIG. 2 is a perspective view showing the state of connection between the switching damper and the control motor, and FIG. 3 is a schematic explanatory view showing another embodiment. l...furnace body, 2...material transfer device, 3...' two-part duct, 4...lower duct, 5...outgoing duct, 6...
・Return duct, 7. Hot air generator, 8. Recirculation blower, 10. Switching damper.

Claims (1)

[Claims] 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. When the upper and lower ducts are connected to each other, a switching damper is provided at the connection part so that the flow of hot air alternately flows from top to bottom and from bottom to top between the upper and lower ducts. A hot air alternating jet heating device characterized by: