JPH11209850A - Heating furnace tube, and use of heating furnace tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating furnace tube capable of giving excellent coking resistance and capable of minimizing reduction in productivity due to decoking treatment and also to provide the use of the heating furnace tube. SOLUTION: The tube is a heating furnace tube used to pass fluids containing hydrocarbon or carbon monoxide and is constituted of a rare earth oxide grain dispersed type iron-base alloy containing, by weight, 19-26% Cr and 3-6% Al. As to the use of the heating furnace tube, a fluid containing hydrocarbon or carbon monoxide is passed through the heating furnace tube composed of a rare earth oxide grain dispersed type iron-base alloy containing, by weight, 19-26% Cr and 3-6% Al.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating furnace tube and a method of using the heating furnace tube, in which coking is a problem, such as a cracking tube (cracking tube) in an ethylene production apparatus.

[0002]

2. Description of the Related Art For example, in a cracking tube in an ethylene production apparatus as a heating furnace tube, carbon is deposited and deposited on the inner surface of the tube in a temperature range in which carbon deposition occurs in a gas atmosphere containing carbon such as hydrocarbons. The problem is the occurrence of so-called coking. That is, if caulking occurs on the inner surface of the heating furnace tube, there is a risk that the operation of the apparatus will be greatly hindered, such as overheating or blockage of the heating furnace tube, so the deposited carbon is burned in a high-temperature steam atmosphere. It is necessary to frequently carry out a so-called decoking process such as removal by removal, and in order to further perform the above decoking process, the operation of the apparatus must be temporarily stopped, resulting in a significant decrease in productivity. There was an inconvenience.

[0003]

In order to solve the above-mentioned inconvenience, a material in which 1 to 10% of Al is added to a ferritic alloy and an oxide film containing Al is formed on the surface,
A technique for forming a heating furnace tube using a material in which a high Al content layer is formed on the surface of a base metal alloy by aluminizing has been developed. However, in the above-mentioned conventional technology, although the improvement of the coking resistance is certainly recognized, the coking resistance is still insufficient to be adopted as a heating furnace tube in an actual industrial furnace. SUMMARY OF THE INVENTION An object of the present invention is to provide a heating furnace tube capable of obtaining extremely good coking resistance in view of the above-described circumstances and thereby preventing a decrease in productivity due to a decoking treatment as much as possible. An object of the present invention is to provide a method of using a heating furnace tube.

[0004]

SUMMARY OF THE INVENTION A heating furnace tube according to the present invention is a heating furnace tube used for flowing a fluid containing hydrocarbon or carbon monoxide.
It is composed of a rare earth oxide particle-dispersed iron alloy containing 3 to 6% by weight of Al.

A method of using a heating furnace tube according to the present invention is as follows: a heating furnace tube made of a rare earth oxide particle-dispersed iron alloy containing 19 to 26% by weight of Cr and 3 to 6% by weight of Al; A fluid containing hydrogen or carbon monoxide is circulated.

[0006]

Embodiments of the present invention will be described below. The heating furnace tube according to the present invention is, for example, a heating furnace tube used for flowing a fluid containing hydrocarbons or carbon monoxide, such as a decomposition tube in an ethylene production apparatus, and is an Al-added ferritic iron. Alloy-based rare earth oxide particle dispersed iron alloy, specifically C
r of 19 to 26% by weight and Al of 3 to 6% by weight,
It is characterized by being composed of an iron alloy dispersed with yttrium oxide particles.

FIG. 1 shows the resistance to coking, high-temperature oxidation, and mechanical properties of alloys of various compositions, including the yttrium oxide particle-dispersed iron alloy constituting the heating furnace tube of the present invention. 3 shows the results of examining high-temperature strength and ductility).

Here, the coking resistance is determined on the basis of a known carbon deposition experiment. That is, emery paper
Prepare a sample (4 x 10 x 45 mm) of each alloy whose surface has been finished with (No. 600) and oxidized with steam at 950 ° C, immerse each sample in a solid carburizing agent and carburize at 1100 ° C And 1100 ° C
Oxidation in the atmosphere at, followed by coking, and then repeating the process of decoking 10 times, examining the weight change before and after coking for each sample, and judging the degree of coking resistance based on the degree of this weight change. ing. The coking conditions were as follows: source gas: benzene (0.5
g / h), carrier gas: argon (16 Nml / min), added amount of S: 1 ppm or less, temperature: 800 ° C., time: 8 hours.

The high-temperature oxidation resistance, high-temperature strength, and ductility are determined by the conditions in which the heating furnace tube is placed, that is, by heating a fluid from the outer periphery by a burner or the like, flowing a high-temperature fluid inside, and constructing an apparatus. In view of the need for mechanical strength, it is a criterion for determining whether or not each alloy material can withstand practical use as a heating furnace tube.

Here, in the table of FIG. 1, ◎ indicates practically sufficient, and ○ indicates
Indicates that the sample can be used, Δ indicates that the sample is insufficient for practical use, and * indicates that the sample cannot be used. In the table of FIG.
Samples No. 8 to No. 15, i.e., an yttrium oxide particle-dispersed iron alloy containing 19 to 26% by weight of Cr and 3 to 6% by weight of Al are suitable for heating furnace tubes in view of coking resistance and other characteristics. It is shown that there is.

On the other hand, FIG. 2 shows a conventional heat-resistant austenitic alloy (high Ni high Cr steel) and an Fe-20Cr-5Al alloy, and one of the materials constituting the heating furnace tube of the present invention, Fe-
₃ shows the results of comparing the coking resistance with a 20Cr-5Al-Y ₂ O ₃ alloy, specifically the change in weight before and after coking.

The high-Ni high-Cr steel and the Fe-20Cr-5Al alloy are both melting materials, whereas Fe-20Cr-5Al-Y ₂ O constituting the heating furnace tube according to the present invention is used. _{The three} alloys are dispersion strengthened alloys manufactured by powder metallurgy.

[0013] The surface of each alloy was finished with emery paper (No. 600) and oxidized with steam at 950 ° C.
× 10 × 45 mm), immerse each sample in solid carburizing agent, carburize at 1100 ° C, oxidize in air at 1100 ° C,
Next, coking was performed, and the process of performing decoking was repeated 10 times, and the weight change before and after coking was examined for each sample. Here, the caulking conditions are
Source gas: benzene (0.5 g / h), carrier gas: argon (16 Nml / min), S addition amount: 1 ppm or less, temperature: 800
° C, time: 8h.

As shown in FIG. 2, the Fe-20Cr-5Al-Y ₂ O ₃ alloy constituting the heating furnace tube of the present invention has a greater caulking resistance than the Fe-20Cr-5Al alloy before and after coking. It is clear from this that the addition of yttrium oxide to the Fe-Cr-Al alloy contributes to a significant improvement in the coking resistance.

[0015] Also, from the comparison results of Samples No5 and No8 in Fig. 1, it is clear that the addition of yttrium oxide to the Fe-Cr-Al alloy contributes to a significant improvement in coking resistance. .

As is clear from the table of FIG.
A ferritic iron alloy containing 6% by weight and 3 to 6% by weight of Al shows relatively excellent coking resistance. In particular, FIG. the _{Fe-20Cr-5Al-Y 2} O 3 alloy showing a comparison result to an example, a sample of yttrium oxide particles distributed iron alloy of No8～ No15, the weight change before and after coking of about 1 mg / c
m ² or less and extremely low, and shows a good coking resistance.

Here, a material containing 28% by weight or more of Cr and 8% by weight or more of Al has a low ductility, specifically, a low elongation at break, and a material having a Cr content of 14% by weight or less has a high temperature range. Are inferior in oxidation resistance, and both have practical problems as materials for heating furnace tubes. Materials without yttrium oxide added to actual heating furnace tubes have low high-temperature strength. It is difficult to apply.

On the other hand, the yttrium oxide particle-dispersed iron alloys of Samples Nos. 8 to 15 to which yttrium oxide was added exhibited improved coking resistance and high-temperature strength. 26% by weight, 3-6 Al
It has been found that a rare-earth oxide particle-dispersed iron alloy containing by weight can be suitably used as a material for a heating furnace tube.

The heating furnace tube according to the present invention is made of a rare earth oxide particle dispersed iron alloy containing 19 to 26% by weight of Cr and 3 to 6% by weight of Al. The method of using the heating furnace tube according to the above is to flow a fluid containing hydrocarbon or carbon monoxide through the heating furnace tube made of the rare earth oxide particle dispersed iron alloy having the above-described composition.

As described above, the rare-earth oxide particle-dispersed iron alloy containing 19 to 26% by weight of Cr and 3 to 6% by weight of Al has extremely good coking resistance. In the heating furnace tube and the method of using the heating furnace tube according to the present invention, the occurrence of coking due to the operation of the apparatus can be suppressed as much as possible, and the interval of the decoking process can be significantly extended as compared with the conventional method. Becomes possible.

As described above, the ability to extend the interval of the decoking process greatly improves the productivity of the apparatus, reduces the cost of the decoking process, stops the operation of the apparatus during the decoking process, and The economic effects obtained by the present invention are extremely large, such as a reduction in thermal fatigue and an increase in life associated with the restart of operation.

In addition, in the decomposition pipe of the ethylene production apparatus, the wall temperature of the pipe exceeds 1000 ° C., and in some places reaches 1100 ° C. In a decomposition pipe made of heat-resistant austenitic metal, its melting point is lower than 1100 ° C. In contrast to the current situation that requires strict control of the operation of the apparatus because it is only about 150 to 200 ° C. higher, the rare earth oxide particle dispersed iron alloy constituting the heating furnace tube of the present invention has a melting point of Since the temperature is 1480 ° C., according to the present invention, while further improving safety,
It goes without saying that the operation of the device can be simplified.

Incidentally, since the heating furnace tube of the ethylene production apparatus is extremely long, the heating furnace tube according to the present invention is used only in a portion where caulking is particularly problematic.
In other parts, heating furnace tubes made of conventional materials are used, and by connecting them to each other, it is advisable from an economical viewpoint to construct the entire heating furnace tube.

On the other hand, the fluid flowing inside the heating furnace tube has S
It is well known that the addition of (sulfur) is effective in suppressing coking.

FIG. 3 shows a rare earth oxide particle dispersed iron alloy constituting the heating furnace tube of the present invention, that is, a rare earth oxide particle dispersed iron containing 19 to 26% by weight of Cr and 3 to 6% by weight of Al. The results of examining the effect of S on the coking resistance of the alloy and the austenitic heat-resistant alloy (25Cr-35Ni steel) constituting the conventional heating furnace tube are shown.

The coking conditions were as follows: raw material gas: 10
% Methane + hydrogen, additive: DMS (methyl sulfide): 0 ppm,
200 ppm (S = 100 ppm in terms of atomic weight), temperature: 900 ° C, 1000
° C, 1100 ° C, time: 5h.

In FIG. 3, the weight change due to coking of the rare earth oxide particle dispersed iron alloy under the condition of adding S is set to 1, and the coking resistance due to the difference in the material, the added amount of S, and the temperature is compared. Is shown.

As is evident from the table of FIG.
At a temperature of 1000 ° C., the addition of S reduces the weight change due to caulking in both the rare-earth oxide particle-dispersed iron alloy according to the present invention and the austenitic heat-resistant alloy as a comparative material (conventional material). .

On the other hand, under the temperature condition of 1100 ° C., in the rare-earth oxide particle-dispersed iron alloy according to the present invention, a decrease in weight change due to coking due to the addition of S is recognized, whereas a comparative material (conventional material) In the austenitic heat-resistant alloy, the weight change due to coking tends to increase due to the addition of S.

As described above, by adding 100 ppm of S in terms of atomic weight, the coking resistance of both the rare-earth oxide particle-dispersed iron alloy and the austenitic heat-resistant alloy can be improved at a temperature of 1000 ° C. or less. It is clear.

Therefore, in a heating furnace tube constructed by connecting a heating furnace tube of the present invention made of a rare earth oxide particle dispersed iron alloy and a heating furnace tube made of an austenitic heat-resistant alloy to each other, the inside of the heating furnace tube is constructed. Converting fluid to atomic weight
Add 100ppm or less of S, 1000 ℃ or less,
And rare earth oxide particles dispersed iron alloy according to the present invention is 47
By using at a temperature of 550 ° C. or more that does not cause brittleness of 5 ° C., good coking resistance is exhibited, and thus it can be suitably used in a hydrocarbon environment where coking tends to occur.

If the amount of S exceeds 100 ppm (in terms of atomic weight), problems related to corrosion of the heating furnace tube and problems related to the post-treatment of S occur, which is not industrially appropriate. The addition of S (sulfur) to the fluid flowing inside the heating furnace tube includes DMS (methyl sulfide) and DMDS which decompose at high temperatures.
(Methyl disulfide) can be suitably used, and a sufficient effect can be expected by further adding hydrogen sulfide gas.

As described above, the entire heating furnace tube in the ethylene production apparatus and the like is connected to the heating furnace tube made of the rare earth oxide particle dispersed iron alloy according to the present invention and the heating furnace tube made of the austenitic heat-resistant alloy. With this configuration, in other words, by using a heating furnace tube made of an austenitic heat-resistant alloy for a part of the entire heating furnace tube, it is possible to greatly reduce the cost of the apparatus.

Further, a heating furnace tube constructed by connecting a heating furnace tube made of a rare earth oxide particle dispersed iron alloy according to the present invention and a heating furnace tube made of an austenitic heat-resistant alloy has an atomic weight of 100 ppm or less. By allowing the fluid containing S to flow and using it in the temperature range of 550 ° C. to 1000 ° C., the occurrence of coking in the rare-earth oxide particle-dispersed iron alloy and the austenitic heat-resistant alloy can be suppressed as much as possible. In addition, the interval between the decoking processes can be greatly extended as compared with the related art.

As described above, the ability to extend the interval of the decoking process greatly improves the productivity of the apparatus, reduces the cost of the decoking process, stops the operation of the apparatus during the decoking process, and The economic effects obtained by the present invention are extremely large, such as a reduction in thermal fatigue and an increase in life associated with the restart of operation.

FIGS. 4 to 6 show a heating furnace tube constructed by connecting a heating furnace tube according to the present invention and a heating furnace tube made of a conventional material to each other, and a method of manufacturing the heating furnace tube. ing.

The heating furnace tube 1 shown in FIG.
One heating furnace tube element 10 made of a heating furnace tube according to the present invention, which is made of a rare earth oxide particle dispersed iron alloy containing 6% by weight and 3 to 6% by weight of Al, and an austenitic heat-resistant alloy The other heating furnace tube element 20
It is configured by bonding to each other by diffusion bonding via an insert metal.

Further, one heating furnace tube element 10 and the other heating furnace tube element 20 in the heating furnace tube 1 are connected to a short joint tube 30 made of an austenitic heat-resistant alloy of the same material as the other heating furnace tube element 20. Are connected to each other.

The other heating furnace tube element 20 includes:
Not only an austenitic heat-resistant alloy but also a rare earth oxide particle dispersed iron alloy of the same material as one of the heating furnace tube elements 10 can be used. Also, as the joint short tube 30, not only the austenitic heat-resistant alloy but also a rare-earth oxide particle-dispersed iron alloy of the same material as that of the one heating furnace tube element 10 can be used.

The heating furnace tube 1 described above is manufactured through the following working steps. First, one heating furnace tube element 10 having an outer diameter of 70 mm and a wall thickness of 5 mm and the other heating furnace tube element 20 having the same size (outer diameter of 70 mm and a wall thickness of 5 mm) as the one heating furnace tube element 10 are provided. The outer surface at each joint end
Grinding is performed over a range of 30 mm from the end face of each pipe element to finish to a surface roughness of 25S.

Next, the outer surface of the joining side end of one heating furnace tube element 10 finished as described above and the outer surface of the joining side end of the other heating furnace tube element 20 are provided with Ni- as insert metal. A film M of a 4% B alloy is formed to a thickness of 50 μm by electroplating. In addition, as the insert metal, for example, BNi brazing metal,
Commercially available amorphous metal products can be used.

Next, the joining side end of one heating furnace tube element 10 and the joining side end of the other heating furnace tube element 20 are respectively connected to the end of the short joint tube 30 by 30 mm.
Insert each. Here, the joint short pipe 30 has an inner diameter of 70 mm,
It has a thickness of 8 mm and a length of 60 mm, and its inner surface 30a is finished to a surface roughness of 25S. In addition, joint short pipe 3
At both ends of the outer circumference of 0, the diameter is reduced to about 10 ° toward the end.
Are formed. In addition, it is possible to form an insert metal film on the inner surface 30a of the joint short pipe 30 together with the joint-side ends of the heating furnace tube elements 10 and 20 described above. It is also possible to form a film of the insert metal only on the inner surface.

A joining-side end of one heating furnace tube element 10;
After the other end of the heating furnace tube element 20 on the joining side is inserted into the joint short pipe 30, the joint short pipe 30 is fastened by the fasteners 40 and 41 attached to the tapered surfaces 30 t and 30 t of the joint short pipe 30. Is shrunk and deformed in the radial direction, so that the joining-side end of each heating furnace tube element 10 and 20 and the inner peripheral surface 30a of the joint short pipe 30 are inserted into the plating layer M of the insert metal.
M is sandwiched and pressed, and they are fastened together by pressing.

The fasteners 40, 41 each have a ring shape, and tapered surfaces 40t, 41t of the same shape as the tapered surfaces 30t, 30t of the joint short pipe 30 are formed on the inner periphery thereof. Each tapered surface 30t of the joint short pipe 30, 3
By moving the joint short pipe 30 in a direction approaching each other in a state of being mounted at 0t, the joint short pipe 30 contracts in the radial direction.

The tapered surface 3 of the joint short pipe 30 described above is used.
Pressing means P for pressing the joint short pipe 30 to one of the heating furnace tube elements 10 and the other heating furnace tube element 20 is constituted by 0t and 30t and the fasteners 40 and 41.

After the one heating furnace tube element 10 and the other heating furnace tube element 20 and the joint short tube 30 are fastened to each other, the inside of each heating furnace tube element 10 and 20 is set to a vacuum degree of 0.0.
Exhaust until 01 Torr or less. Note that 10 in FIG.
Reference numerals A and 20A denote partition walls attached to seal the end openings of the heating furnace tube elements 10 and 20 when the insides of the heating furnace tube elements 10 and 20 are evacuated.

The interior of each heating furnace tube element 10, 20 is evacuated to prevent the oxidation of the coating M of the insert metal, and the fastening state between each heating furnace tube element 10, 20 and the joint short pipe 30 is reduced. You can check.

Further, since the heating furnace tube elements 10 and 20 are fastened via the joint short pipe 30, the centering (center axis alignment) of one heating furnace tube element 10 and the other heating furnace tube element 20 is performed. ) Is performed easily, and the inside and outside airtightness of each heating furnace tube element 10 and 20 is improved.

In order to prevent oxidation of the coating metal M of the insert metal, each of the heating furnace tube elements 10 and 20 is evacuated.
May be filled with an inert gas, and further, the inside of each heating furnace tube element 10, 20 may be filled with an inert gas without exhausting.

After evacuating the inside of each of the heating furnace tube elements 10 and 20, the insert metal film M is melted by high frequency heating from the inside of each of the heating furnace tube elements 10 and 20 by the inserted heater H. Temperature, and the temperature is maintained at this temperature for one hour, thereby promoting diffusion bonding (liquid phase diffusion bonding). Note that, instead of high-frequency heating, it is also possible to perform melting of the insert metal film M and diffusion bonding by infrared heating.

Here, when the heating furnace tube elements 10 and 20 are heated from the inside, the heating furnace tube elements 10 and 20 thermally expand in the radial direction, so that the fastening force by the pressurizing means P described above is reduced. Together, each heating furnace tube element 1 during heating
A decrease in the joining pressure between the 0, 20 and the joint short pipe 30 is prevented beforehand.

After the diffusion bonding is completed by maintaining the high temperature for one hour, the furnace is allowed to cool to room temperature, and the fasteners 40 and 41 are removed from the short joint tube 30, whereby the manufacturing process of the heating furnace tube 1 is completed. That is, as shown in FIG. 3, the completed heating furnace tube 1 has an appearance in which the joint short pipe 30 is fitted to a connection portion between one heating furnace tube element 10 and the other heating furnace tube element 20. It will be.

According to the heating furnace tube 1 configured as described above,
By using the other heating furnace tube element 20 partially made of an austenitic heat-resistant alloy, the cost of the apparatus can be significantly reduced.

The heating furnace tube 1 having the above-described structure is
By flowing a fluid containing 100 ppm or less of S in terms of atomic weight and using the fluid in a temperature range of 550 ° C. to 1000 ° C., one of the heating furnace tube elements 10 made of a rare earth oxide particle dispersed iron alloy, In the other heating furnace tube element 20 made of a heat-resistant alloy, the occurrence of coking can be suppressed as much as possible, so that the interval between the decoking treatments can be greatly extended as compared with the conventional case, which is extremely large. Economic effects can be obtained.

The heating furnace tube and the method of using the heating furnace tube according to the present invention are not limited to cracking tubes in ethylene production equipment, but also include various heating furnaces in which coking is a problem, such as a CCR device in an oil refinery plant. It goes without saying that the present invention can be applied very effectively to pipes.

[0056]

As described above in detail, the heating furnace tube according to the present invention is a heating furnace tube used for flowing a fluid containing hydrocarbons or carbon monoxide, and contains one Cr.
It is composed of a rare earth oxide particle dispersed iron alloy containing 9 to 26% by weight and 3 to 6% by weight of Al. Further, the method of using the heating furnace tube according to the present invention is as follows. The heating furnace tube made of a rare earth oxide particle dispersed iron alloy containing 19 to 26% by weight of Cr and 3 to 6% by weight of Al contains A fluid containing carbon oxide is circulated. Here, Cr is 19
Since the rare-earth oxide particle-dispersed iron alloy containing up to 26% by weight and 3 to 6% by weight of Al has extremely good coking resistance, the heating furnace tube and the heating furnace tube according to the present invention can be used. According to the method of use, the occurrence of coking due to the operation of the apparatus can be suppressed as much as possible, and the interval between the decoking processes can be greatly extended as compared with the related art. As described above, according to the heating furnace tube and the method of using the heating furnace tube according to the present invention, the interval of the decoking process can be extended as compared with the conventional method of using the heating furnace tube and the heating furnace tube. Thus, it is possible to prevent a decrease in productivity due to the decoking process.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the coking resistance, high temperature oxidation resistance, and mechanical properties of alloys of various compositions including a rare earth oxide particle dispersed iron alloy constituting a heating furnace tube according to the present invention. Table showing the results.

FIG. 2 shows the relationship between the Fe-20Cr-5Al-Y ₂ O ₃ alloy, which is one of the materials constituting the heating furnace tube according to the present invention, and the conventional austenitic heat-resistant alloy and Fe-20Cr-5Al alloy. , A graph showing a comparison of coking resistance.

FIG. 3 shows the effect of S on the coking resistance of the rare-earth oxide particle-dispersed iron alloy constituting the heating furnace tube according to the present invention and the austenitic heat-resistant alloy constituting the conventional heating furnace tube. A table showing the results of the examination.

FIG. 4 is an external perspective view of a main part of a heating furnace tube formed by connecting a heating furnace tube according to the present invention and a heating furnace made of a conventional material.

FIG. 5 is an external perspective view showing components and fasteners of a heating furnace tube formed by connecting a heating furnace tube according to the present invention and a conventional heating furnace.

FIG. 6 is a cross-sectional side view of a main part showing a configuration when a heating furnace tube according to the present invention and a conventional heating furnace are connected.

[Explanation of symbols]

 1 ... whole heating furnace tube, 10 ... one heating furnace tube element (heating furnace tube), 20 ... other heating furnace tube element, M ... coating of insert metal.

Continued on the front page (72) Inventor Keizo Hosoya 2-3-1 Minatomirai, Nishi-ku, Yokohama-shi, Kanagawa Prefecture JGC Corporation Yokohama Head Office (72) Inventor Hayashi Sasano 2205 Narita-cho, Oarai-machi, Higashiibaraki-gun, Ibaraki Prefecture JGC Corporation Inside the Technical Research Institute (72) Inventor Kenji Sato 2205 Narita-cho, Oarai-machi, Higashi-Ibaraki-gun, Ibaraki Prefecture Inside the Technical Research Institute (72) Inventor Toshikazu Nakamura 2205 Narita-cho, Oarai-machi, Higashi-Ibaraki-gun, Ibaraki (72) Inventor Shigen Ichimura 2205 Narita-cho, Oarai-machi, Higashiibaraki-gun, Ibaraki Pref.

Claims (6)

[Claims] 1. A heating furnace tube used for flowing a fluid containing a hydrocarbon or carbon monoxide, comprising rare earth oxide particles containing 19 to 26% by weight of Cr and 3 to 6% by weight of Al. A heating furnace tube comprising a dispersed iron alloy. 2. A further furnace tube element made of a refractory metal,
2. The heating furnace tube according to claim 1, wherein the heating furnace tube is connected by diffusion bonding via an insert metal. 3. A fluid containing 100 ppm or less of S in terms of atomic weight is allowed to flow, and 550.degree.
The heating furnace tube according to claim 2, wherein the heating furnace tube is used in a temperature range of ° C. 4. A Cr content of 19 to 26% by weight and an Al content of 3 to 6%.
What is claimed is: 1. A method for using a heating furnace tube comprising: flowing a fluid containing hydrocarbon or carbon monoxide through a heating furnace tube made of a rare earth oxide particle-dispersed iron alloy containing 1% by weight. 5. Another furnace tube element made of a refractory metal,
5. The method of using a heating furnace tube according to claim 4, wherein the heating furnace tube is used by being bonded by diffusion bonding via an insert metal. 6. A fluid containing 100 ppm or less of S in terms of atomic weight is allowed to flow, and 550 ° C. to 1000
The method for using a heating furnace tube according to claim 5, wherein the heating furnace tube is used in a temperature range of ° C.