JPH0820817A - Radiation heating tube - Google Patents

Abstract

PURPOSE:To obtain a radiation heating tube, in which the deformation and the crack can be prevented without casting defect and the wt. can be reduced by making the thickness thinner and the temp. control and the heat efficiency in a heating furnace can be improved. CONSTITUTION:In the radiation heating tube for heating the inner part of the heating furnace with the radiating heat generated while combustion gas (g) flows in the tube body 21 by introducing the combustion gas (g) into the tube body 21 from one end part of the tube body 21 arranged in the heating furnace, the tube body 21 is assembled with one or more of U-shape tube parts 22a-22c and one or more of straight tube parts 13a, 13b, 14a, 14b. The U-shape tube parts 22a-22c are connected with plural tube members 24, 24... by rounding the sheet materials made of a thin heat resistant alloy and butt-welding both end parts under communicating condition, and the straight tube parts 13a, 13b, 14a, 14b are cast tubes made of the heat resistant alloy. By this constitution, the radiation heating tube having easy handling at the time of fitting or at the time of changing, is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is arranged in a heating furnace,
The present invention relates to a radiant heating tube that heats the inside of a heating furnace by radiant heat generated while the introduced combustion gas flows in the tube body.

[0002]

2. Description of the Related Art FIG. 2 shows, for example, Japanese Patent Laid-Open No. 3-22651.
It is a perspective view which shows the state which the conventional radiant tube (radiant heating tube) shown by the 9th publication was arrange | positioned in the heating furnace. In the figure, 1 is filled with non-oxidizing gas, such as RX gas, and carburizing gas. Heating furnace, 2 is placed in heating furnace 1
It is a tube body (tube body) having a vent portion (U-shaped tube portion) 2a. The tube body 2 is composed of a cast tube made of an iron-based alloy, and is generally produced by centrifugal casting or static casting. In FIG. 2, 3 is a heating furnace 1.
It is a mesh conveyor which is arranged inside and is movable in a predetermined direction. This radiant tube, as shown in Figure 3,
The support 5 fixed to the outside of the U vent portion 2a is supported by abutting on a support fitting 6 fixed to one inner wall of the heating furnace 1, and the vicinity of the U vent portion 2a is suspended by a wire 7. . As shown in FIG. 4, this radiant tube burns gas by a burner 9 provided at one end of the tube body 2, and the radiant heat generated while the combustion gas g flows in the tube body 2 The inside of the heating furnace 1 is heated.

This radiant tube has a high temperature atmosphere in the heating furnace 1 (900 to 9 in the case of being used for carburizing).
Since it is arranged at 50 ° C, which is about 1150 ° C in the case used for sintering treatment, the tube body 2 is softened by heat and its own weight creep causes it to be indicated by a chain double-dashed line in FIG. Such deformation occurs, and in some cases, there is a problem such as damage. Therefore, the conventional radiant tube is composed of a cast tube having excellent heat resistance.

FIG. 5 is a vertical sectional view showing a conventional W-type radiant tube (radiant heating tube). In the figure, 11 is arranged in a heating furnace and three U vent portions (U
Tube body (tube body) formed by connecting and disposing the straight tube portions) 12a to 12c, the straight tube portions 13a and 13b, and the straight tube portions 14a and 14b so as to form a W shape, and 15 and 16 are U vent portions 12a. ~ 12c and a support fixed to the outside of the straight pipe portion 13b, 17 is a flange provided around the openings of the straight pipe portions 13a and 13b, 18 is a burner bang extending from the flange 17b toward the vicinity of the flange 17a, and 19 is It is a bellows. U vent parts 12a to 12c and straight pipe part 1
3a, 13b, 14a and 14b are mainly composed of Fe and N
It is composed of a cast pipe made of an iron-based alloy containing a predetermined amount of i and Cr, and is generally produced by centrifugal casting or static casting. This radiant tube has a straight pipe portion 13a.
Combustion gas g is introduced into the straight pipe portion 13a from one end of the heating furnace, and the inside of the heating furnace is heated by the radiant heat generated while the combustion gas g flows in the tube body 11.

[0005]

By the way, in each of the conventional radiant tubes, since the tube bodies 2 and 11 are formed by casting tubes, casting defects are likely to occur, and there is a risk of deformation and cracking. Since the wall thickness is large and the minimum wall thickness is limited to about 8 mm, the weight increases,
There is a problem that the bending moment generated at a high temperature becomes large and it is easily deformed. In addition, since the heat capacity of the tube bodies 2 and 11 themselves is large, the thermal efficiency is poor, and the temperature followability due to temperature rise / fall is poor and it is difficult to control the temperature in the heating furnace. There is a problem that heat is absorbed by the tube bodies 2 and 11 and the heat efficiency is poor. In addition, since it is heavy, it is inconvenient to handle when mounting or replacing.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to prevent deformation and cracks without casting defects, and to reduce the weight by reducing the wall thickness. It is an object of the present invention to provide a radiant heating tube which can improve temperature control and thermal efficiency in the furnace and which can be easily handled during installation and replacement.

[0007]

In order to solve the above problems, the present invention employs the following radiant heating tube. That is, the radiant heating pipe according to claim 1 comprises a pipe main body having one or more U-shaped pipe portions and one or more straight pipe portions,
The character tube portion is formed by connecting a plurality of pipe members formed by rolling a thin plate made of a heat-resistant alloy and butt-welding both ends in a communicating state, and the straight pipe portion is a cast pipe made of a heat-resistant alloy. It is characterized by that.

The radiant heating pipe according to claim 2 comprises a pipe main body having one or more U-shaped pipe portions and one or more straight pipe portions, and the U-shaped pipe portion is made of a thin heat-resistant alloy. The plate material is rounded into a substantially semicircular shape in cross section, and the end portions along the longitudinal direction of a pair of pipe members that are curved so that one end portion along the longitudinal direction is on the outside are butt-welded together. The straight pipe portion is a cast pipe made of a heat-resistant alloy.

A radiant heat generating tube according to a third aspect is the radiant heat generating tube according to the first or second aspect, characterized in that the straight pipe portion is formed by rolling a plate material made of a thin heat-resistant alloy and butt-welding the ends thereof. I am trying.

The radiant heating tube according to claim 4 is the radiant heating tube according to claim 1,
The radiant heating tube according to 2 or 3 is characterized in that the plate material is a nickel-based alloy containing nickel as a main component.

The radiant heating tube according to claim 5 is the radiant heating tube according to claim 1,
The radiant heating tube described in 2 or 3 is characterized in that the plate material is an iron-based alloy containing iron as a main component.

[0012]

In the radiant heating pipe according to the first aspect of the present invention, the U-shaped pipe portion is connected in a communicating state with a plurality of pipe members formed by rolling a plate material made of a thin heat-resistant alloy and butt-welding both ends thereof. By doing so, there is no possibility of causing a casting defect as in the conventional case. Further, since the wall thickness is thin and the weight is small, the bending moment generated at high temperature is small. Further, since the heat capacity of the U-shaped tube portion itself becomes small, the thermal efficiency, the temperature follow-up property due to the temperature rise / fall, and the temperature controllability in the heating furnace are improved. In addition, the small weight facilitates handling during installation and replacement.

In the radiant heating pipe according to the second aspect of the present invention, the U-shaped pipe portion is formed by rolling a plate material made of a thin heat-resistant alloy into a substantially semicircular cross section, and one end portion along the longitudinal direction is the outside. Since the end portions along the longitudinal direction of the pair of curved pipe members are butt-welded to each other, there is no possibility of causing a casting defect as in the conventional case. Further, since the wall thickness is thin and the weight is small, the bending moment generated at high temperature is small. Further, since the heat capacity of the U-shaped tube portion itself becomes small, the thermal efficiency, the temperature follow-up property due to the temperature rise / fall, and the temperature controllability in the heating furnace are improved. In addition, the small weight facilitates handling during installation and replacement. Further, since the ends of the pair of pipe members may be butt-welded together, the number of welding points is reduced and the welding process is shortened.

In the radiant heating pipe according to the third aspect of the present invention, the straight pipe portion may be formed by rolling a plate material made of a thin heat-resistant alloy and butt-welding the ends thereof, so that a casting defect may occur in the entire radiant heating pipe. Disappears. In addition, since the entire wall thickness is thin and the weight is small, the bending moment of the entire radiant heating tube at high temperature is small. Also, thermal efficiency,
The temperature followability associated with temperature rise / fall and the temperature controllability in the heating furnace are further improved. In addition, handling at the time of mounting or replacement becomes easier.

In the radiant heating tube according to the present invention, the plate material is a nickel-based alloy containing nickel as a main component, so that a non-oxidizing gas such as RX gas or a carburizing gas of a tube member using the plate material is used. Corrosion resistance and heat resistance are improved.

In the radiant heating tube according to the fifth aspect, since the plate material is an iron-based alloy containing iron as a main component, the heat resistance of the tube member using the plate material is improved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the radiant heating tube of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical cross-sectional view showing a W-shaped radiant tube (radiant heating tube). In the figure, 21 is arranged in a heating furnace and three U vents (U
Tube body (tube body) 22a to 22c, straight tube portions 13a and 13b, and straight tube portions 14a and 14b arranged and connected in a W shape, and 23 is a straight tube portion 13a, 1
It is a support provided between 4a.

The U vent portion 22a (22b, 22c) is
For example, Cr is 22% by weight, W is 14% by weight, and Mo is 2%.
A plurality of pipe members each having a thin plate member made of a Ni-based alloy, which is contained in a weight percentage, are rounded into a cylindrical shape and both ends thereof are butt-welded, and the openings at both ends of the cylindrical shape are inclined at a predetermined angle θ with respect to an axis line. , 24, ... Are connected in a communicating state so that the overall shape is a substantially semi-annular shape.

In this radiant tube, the U vents 22a to 22c are formed by rolling a thin plate material made of a Ni-based alloy into a tube so that it is less likely to be corroded by a non-oxidizing gas such as RX gas or carburizing gas, and heat resistance is improved. The property is improved. Further, as compared with the conventional casting pipe, there is no possibility of causing a casting defect, and there is no possibility of causing deformation or cracking due to the casting defect. In addition, since the wall thickness is thin and the weight is small, the bending moment generated at high temperature becomes small and it becomes difficult to deform. Further, since the heat capacity of the U-shaped tube portion itself is reduced, the thermal efficiency in the U-shaped tube portion is improved, the temperature followability accompanying the temperature rise / fall is improved, and therefore the temperature controllability in the heating furnace is improved. . Further, since the weight is small, handling at the time of mounting or replacement becomes easy, and workability is improved.

As described above, according to the radiant tube of this embodiment, the U vent portions 22a to 22c are connected to N
Since a plurality of pipe members 24, 24, ..., Which have been butt-welded at both ends and which are formed by rolling a thin plate material made of an i-based alloy into a cylindrical state, are connected in a communicating state, the U vent portions 22a to 22c are provided.
It is possible to improve corrosion resistance and heat resistance to non-oxidizing gas such as RX gas and carburizing gas. Further, as compared with the conventional casting pipe, there is no possibility of causing a casting defect, there is no possibility of causing deformation or cracking due to the casting defect, and the reliability of the U vent portions 22a to 22c can be improved. Further, the wall thickness is thin and the weight is small, the bending moment generated at a high temperature can be reduced, and the deformation can be made difficult. Also, the U vent portion 22a to
The heat capacity of 22c itself becomes small, the thermal efficiency in the U-shaped tube portion, the temperature followability with temperature rise / fall and the temperature controllability in the heating furnace are improved, and more energy saving and more accurate temperature control can be performed. it can. Further, the weight is small, the handling at the time of mounting or replacement can be facilitated, and the workability can be improved.

In this embodiment, the U vent portions 22a ...
22c has a structure in which a plurality of pipe members 24, 24, ..., Which are formed by rounding a thin plate material into a cylindrical shape and butt-welded at both ends, are connected in a communicating state, the U vent portions 22a to 22c are thin plate materials. May be rounded into a substantially semicircular cross section, and the end portions along the longitudinal direction of a pair of pipe members curved so that one end portion along the longitudinal direction thereof is on the outside may be butt-welded together. . In this case, since the ends of the pair of pipe members may be butt-welded together, the number of welded portions can be reduced in addition to the effect similar to that of the U vent portions 22a to 22c, and the welding process can be shortened. It is possible to achieve the effect.

The composition of the U vents 22a to 22c is a Ni-based alloy containing 22% by weight of Cr, 14% by weight of W and 2% by weight of Mo. However, the composition is not limited to this composition. Of course, Ni-based alloys having other compositions may be used. In addition to the above Ni-based alloy, for example, SUS31
Even if an iron-based alloy such as stainless steel such as 0S is used, U
The heat resistance of the vent parts 22a to 22c can be improved.

Further, only the U vent portions 22a to 22c are formed into a plurality of pipe members 24, 24, ... Which are made by thinly rolling a thin plate material into a cylindrical shape and butt-welding the both ends, but are connected in a communicating state. However, the straight pipe portions 13a, 13b, 14
Alternatively, a and 14b may be obtained by rolling a thin plate material into a cylindrical shape and butt-welding both ends. In this case, the U vent part 2
In addition to the same effects as 2a to 22c, it is possible to prevent the occurrence of casting defects in the entire radiant tube. Since the entire wall thickness is thin and the weight is small, the bending moment of the entire radiant tube at high temperature can be reduced, and the entire radiant tube can be made difficult to deform. Thermal efficiency,
It is possible to further improve the temperature followability with temperature rise / fall and the temperature controllability in the heating furnace. It is possible to achieve excellent effects such as easier handling at the time of mounting or replacement.

[0024]

As described above, according to the radiant heating tube of the first aspect of the present invention, the U-shaped tube portion is formed by rolling a plate material made of a thin heat-resistant alloy and butt-welding both ends thereof. Since it is configured to connect a plurality of pipe members in a communication state, there is no risk of casting defects compared to conventional casting pipes,
There is no risk of deformation or cracking due to casting defects, and the reliability of the U-shaped pipe portion can be improved. Further, the wall thickness is thin, the weight is small, the bending moment generated at a high temperature is small, and it is difficult to deform. Further, the heat capacity of the U-shaped tube portion itself becomes small, and the thermal efficiency in the U-shaped tube portion, the temperature followability due to temperature rise / fall, and the temperature controllability in the heating furnace are improved, resulting in more energy saving and higher temperature accuracy. Can manage. Also,
The weight is small, handling at the time of mounting or replacement can be facilitated, and workability can be improved.

According to the radiant heating tube of the second aspect, the U-shaped tube portion is formed by rolling a plate material made of a thin heat-resistant alloy into a substantially semicircular cross section, and one end portion along the longitudinal direction thereof. Since the end portions along the longitudinal direction of the pair of pipe members that are curved to the outside are butt-welded together, there is no risk of deformation or cracking due to casting defects, and the U-shaped pipe portion The reliability can be improved. Further, the wall thickness is thin, the weight is small, the bending moment generated at a high temperature is small, and it is difficult to deform. Also,
The heat capacity of the U-shaped tube itself becomes smaller, improving the thermal efficiency in the U-shaped tube, the temperature followability associated with temperature rise / fall, and the temperature controllability in the heating furnace, resulting in more energy saving and more accurate temperature management. It can be carried out. Further, the weight is small, the handling at the time of mounting or replacement can be facilitated, and the workability can be improved. Furthermore, the number of welding points can be reduced, and the welding process can be shortened.

According to the radiant heat generating tube of claim 3, since the straight pipe portion is formed by rolling a plate material made of a thin heat-resistant alloy and butt-welding the ends thereof, a casting defect is formed on the entire radiant heat generating tube. There is no risk of deformation or cracking due to
The reliability of the radiant heating tube as a whole can be improved.
In addition, the overall thickness is thin and the weight is small, the bending moment generated at high temperature is small, and it is possible to make the entire radiant heating tube more difficult to deform. In addition, the heat capacity of the radiant heating tube as a whole is reduced, and the thermal efficiency, the temperature followability accompanying temperature rise and decrease, and the temperature controllability in the heating furnace are improved,
More energy saving and more accurate temperature control can be performed. In addition, the weight of the entire radiant heat generating tube is small, and handling at the time of mounting or replacement can be further facilitated,
Workability can be further improved.

According to the radiant heating tube of the fourth aspect, since the plate material is a nickel-base alloy containing nickel as a main component, a non-oxidizing gas such as RX gas or carburizing of a tube member using the plate material is used. Corrosion resistance and heat resistance to gas can be improved.

According to the radiant heating tube of the fifth aspect, since the plate material is an iron-based alloy containing iron as a main component, the heat resistance of the tube member using the plate material can be improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a W-shaped radiant tube (radiant heating tube) according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a heating furnace using a conventional radiant tube.

FIG. 3 is a side view showing a conventional radiant tube installation structure.

FIG. 4 is a partially cutaway plan view showing a conventional radiant tube.

FIG. 5 is a vertical cross-sectional view showing a conventional W-type radiant tube.

[Explanation of symbols]

 13a, 13b, 14a, 14b Straight pipe part 21 Tube main body (tube main body) 22a-22c U Vent part (U-shaped pipe part) g Combustion gas

Claims (5)

[Claims] 1. A furnace in which a combustion gas is introduced into the tube body from one end of a tube body arranged in the furnace, and the radiant heat generated while the combustion gas flows in the tube body A radiant heat generating tube for heating, wherein the tube main body includes one or more U-shaped tube portions and one or more straight tube portions, and the U-shaped tube portion is formed of a thin heat-resistant alloy plate material. A radiant heat generating pipe, characterized in that a plurality of pipe members formed by rolling and butt-welding both ends are connected in a communicating state, and the straight pipe portion is a cast pipe made of a heat-resistant alloy. 2. The inside of the heating furnace by radiant heat generated while introducing combustion gas into the tube body from one end of the tube body arranged in the heating furnace and flowing through the inside of the tube body. A radiant heat generating tube for heating, wherein the tube main body includes one or more U-shaped tube portions and one or more straight tube portions, and the U-shaped tube portion is formed of a thin heat-resistant alloy plate material. The end portions along the longitudinal direction of a pair of pipe members that are rounded to have a substantially semicircular cross section and that are curved so that one end portion along the longitudinal direction thereof is on the outside are butt-welded together, and The radiant heat generating tube, wherein the tube portion is a cast tube made of a heat-resistant alloy. 3. The radiant heating pipe according to claim 1, wherein the straight pipe portion is formed by rolling a plate material made of a thin heat-resistant alloy and butt-welding the ends. 4. The radiant heating tube according to claim 1, wherein the plate material is made of a nickel-based alloy containing nickel as a main component. 5. The radiant heating tube according to claim 1, wherein the plate member is made of an iron-based alloy containing iron as a main component.