JP2876206B1 - How to control and prevent carburization and metal dusting - Google Patents

Abstract

An object of the present invention is to reduce or prevent carburizing and metal dusting at low cost and easily in a plant component that performs a reaction or the like using a high-temperature carburizing gas. SOLUTION: A metal member having a surface strain applied in advance to a contact surface of a carburizing gas in a plant component device is used. This surface strain is applied by at least one of grinding, shot peening, rolling, forging, and pipe expansion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to suppression of carburization and metal dusting in plant components such as reactors, heat exchangers and gas heaters for performing reactions and heat exchange using high-temperature carburizing gas. It concerns prevention methods.

[0002]

2. Description of the Related Art Carburizing gas containing hydrocarbons, carbon dioxide, carbon monoxide, etc. is used in various plant equipment such as an anchor carbide (iron carbide) manufacturing apparatus, a direct reduction iron making furnace, a styrene monomer manufacturing apparatus, and an ethylene cracking furnace. The member exposed to the atmosphere at a high temperature of 450 to 1000 ° C.
There is a problem that it is damaged by carburization and metal dusting. Metal dusting means that metals and alloys are decomposed into dust in a carburizing atmosphere to reduce corrosion. Specifically, carburization proceeds, and fine metal powder dust and carbon are formed, and these are blown off by a gas flow or the like, causing pits and abrasion loss.

[0003] As methods for suppressing and preventing the above carburizing and metal dusting, the following three points are mainly known. (1) Use a material of a high Ni-Cr alloy, or use a diffusion treatment of Al or Cr or a coating material of a high Ni-Cr alloy. (2) A stable chromium oxide film is formed on the surface. (3) Add a small amount of hydrogen sulfide to the reaction gas.

As a technique for preventing carburization, Japanese Utility Model Application Laid-open No.
No. 4543 discloses a heat-exchange tube having a cone made of a corrosion-resistant and heat-resistant superalloy provided at a hot gas upstream end of a heat-exchange tube, and a carburization inhibiting layer formed on an outer surface of the cone. A hot-gas quenching device that prevents carburization and erosion of the steel is disclosed. In addition, 60-37055
Japanese Unexamined Patent Publication (Kokai) No. H11-175686 discloses a structure for preventing cracking of a blast furnace steel in which a sprayed metal for preventing carburization is provided on the inner surface of the blast furnace steel so as to prevent carburization even if a thermal load is directly applied to the steel. Japanese Utility Model Application Laid-Open No. 59-169347 discloses a shaft having a key groove formed by applying a carburizing agent for preventing carburization during high-temperature heating to a key groove processing portion and carburizing and quenching. .

[0005]

The above conventional method (1)
In contrast, it is very effective to increase the content of Ni or Cr, but there is a problem that it is expensive. Diffusion treatment of chromium and aluminum is also effective as a technique for suppressing carburization and metal dusting.
There is a problem that it cannot be applied to large members. The conventional method (2) has a problem that a method of stably producing a chromium oxide film on an actual machine is very complicated, and it is very difficult particularly in the case of on-site construction. The use of hydrogen sulfide in (3) is extremely effective,
Not applicable due to safety and process issues. Further, the technology described in the above publications uses a corrosion-resistant and heat-resistant superalloy, a sprayed metal or a carburizing agent for a metal member that is susceptible to carburization. No technical idea of applying a surface strain to a member in advance is disclosed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a metal member in contact with a high-temperature carburizing gas in advance by applying surface strain (plastic working or plastic strain) to reduce cost. Another object of the present invention is to provide a method for suppressing and preventing carburizing and metal dusting easily and easily.

[0007]

In order to achieve the above-mentioned object, a method for suppressing and preventing carburizing and metal dusting according to the present invention is described in detail. (Plastic strain) is used. In the above method, the surface strain (plastic strain) is determined by grinding, shot peening, rolling,
It is added by at least one of forging and expansion. Shot peening is a processing method in which hard small particles (abrasive grains) such as metal and sand are accelerated, and the accelerated small particles collide with a processing surface to perform a surface hardening treatment. Also,
Grinding refers to grinding using a cutting tool such as a bite or cutter such as a shaper or lathe, or processing using abrasive grains such as a grinder. When a force is applied to a metal to deform it to a certain degree or more, the metal has a property (plasticity) that keeps almost the same shape even after removing external force, and surface strain is applied by using the various means described above.

Further, the method for suppressing and preventing carburizing and metal dusting according to the present invention provides a method in which a metal member that comes into contact with a high-temperature carburizing gas in a component of a plant is subjected to surface treatment by grinding or shot peening in advance. Is added. In this case, surface distortion can be applied by local construction. In addition, the method for suppressing and preventing carburizing and metal dusting according to the present invention is characterized in that grinding and shot peening are performed on any of the welded heat affected zone and the welded metal zone of the welded structural material in contact with the high-temperature carburizing gas in the component equipment of the plant. The surface strain is added in advance by any one of the above processing processes. Further, the method for suppressing and preventing carburizing and metal dusting according to the present invention includes applying a surface strain to a cast material contacted with a high-temperature carburizing gas in a component of a plant by grinding or shot peening in advance. It is characterized by.

In the method of the present invention, the term "carburizing gas" refers to a gas containing at least one of hydrocarbon, carbon dioxide and carbon monoxide. Usually, it contains the above three components, and often contains hydrogen, water vapor, and the like. Also, “high temperature” refers to 450 to 1000 ° C.,
Usually, it is often the case of 500 to 900 ° C.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications. . The present invention is a method for suppressing or preventing carburization and metal dusting by applying strong working (plastic working) to the surface (inner surface) of a metal material or a metal member to leave surface strain (plastic strain). Specifically, carburizing and metal dusting are performed by mechanically applying strong working to the surface of a metal material or metal member by rolling, forging, grinding such as grinder grinding / shaper grinding, shot peening, pipe expansion processing, etc. Suppress or prevent.

When a rolled material or a forged material is used, a cold-worked material is more preferable than a hot-worked material for carburization resistance and metal dusting. It is necessary to add grinding such as grinder grinding and shaper grinding and strong mechanical processing such as shot peening. In the case of a cast material, grinding such as grinder grinding and shaper grinding and strong mechanical processing such as shot peening are performed instead of using the casting surface as it is. In the case of a welded structural material, grinding such as grinder grinding and shaper grinding and strong mechanical processing such as shot peening are applied to the weld heat affected zone and the welded metal zone. In particular, even if a rolled material or a forged material is used, if the surface distortion has been removed by heat during welding, the above-described strong machining of the surface is performed.

[0012]

EXAMPLES Examples and comparative examples are shown below to further clarify the features of the present invention. Example 1, Comparative Example 1 3 mm thick and 10 m wide from the heat affected zone of SUS310S
Two test pieces having a length of 20 mm and a length of 20 mm were collected. Then, the surface of one test piece was ground with a shaper to add a plastic working part (surface ground material), and the surface of the other test piece was ground with a shaper. Two types of treated test pieces, one with the processed part removed (surface buffing abrasive), were prepared and prepared. These treated test pieces were kept at 700 ° C. for 100 hours in a carburizing atmosphere of a carburizing gas composed of 60 vol.% Of methane gas, 35 vol.% Of hydrogen, and the balance being carbon monoxide, carbon dioxide, steam and ethane. Thereafter, the carburized depth was measured by observing the cross-sectional structure. 1 and 2 show the cross-sectional microstructures of the test piece after carburizing and metal dusting in Example 1, and FIGS.
Shows the cross-sectional microstructure of the test piece after carburizing and metal dusting in Comparative Example 1. FIG. 5 shows the carburized depth of the surface abrasive in Example 1 and the surface buff abrasive in Comparative Example 1.

From FIG. 1 to FIG. 5, in the surface abrasive in Example 1, a plastic strain (strain line indicated by an oblique line on the surface in FIG. 2) is formed on the surface, so that the carburizing depth is 1
Although it is as small as about 8 μm, in the surface buffing abrasive in Comparative Example 1, since the plastic strain on the surface is polished and removed, it can be seen that the carburizing depth is as large as about 70 μm.
Thus, it was apparent that the carburized depth of the heavily worked material (Example 1) was significantly shallower than that of the unstrained material (Comparative Example 1). Further, by suppressing carburization, metal dusting can be suppressed.

[0014]

As described above, the present invention has the following effects. (1) In a plant component that performs a reaction or the like using a high-temperature carburizing gas, low-cost and easy carburizing or metal dusting is performed by applying surface strain (plastic strain) to the contact surface of the gas in advance. Can be suppressed or prevented.

[Brief description of the drawings]

FIG. 1 is an optical microscope photograph (100 × magnification) showing a cross-sectional microstructure of a metal test piece after carburizing and metal dusting in Example 1 of the present invention.

FIG. 2 is an enlarged photograph of FIG. 1 (magnification: 400 times).

FIG. 3 is an optical microscope photograph (100 × magnification) showing a cross-sectional microstructure of a metal test piece after carburizing and metal dusting in Comparative Example 1.

FIG. 4 is an enlarged photograph of FIG. 3 (magnification: 400 times).

FIG. 5 is a graph showing the results of Example 1 and Comparative Example 1, and showing the difference in carburizing depth between the surface ground material and the surface buff abrasive.

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kenichi Yajima 3-1-1, Higashikawasaki-cho, Chuo-ku, Kobe Kawasaki Heavy Industries, Ltd. Kobe Plant (56) References JP-A-3-107148 (JP, A) Kaihei 6-182427 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C12D 7/06 B23P 9/00 C23C 8/00-8/22 B24C 1/10

Claims (5)

(57) [Claims] 1. A method for suppressing and preventing carburizing and metal dusting, comprising using a metal member having a surface strain applied in advance to a contact surface of a carburizing gas in a plant component. 2. The method according to claim 1, wherein the surface strain is ground, shot peened,
The method for suppressing and preventing carburizing and metal dusting according to claim 1, wherein the method is applied by at least one of rolling, forging, and expanding. 3. A method for suppressing and preventing carburizing and metal dusting, wherein a surface strain is previously applied to a metal member in contact with a carburizing gas in a plant component by grinding or shot peening. . 4. A method in which surface distortion is applied in advance to any one of a welded heat affected zone and a welded metal portion of a welded structural material contacted by a carburizing gas in a plant constituent device by any one of grinding and shot peening. Characteristic method of controlling and preventing carburizing and metal dusting. 5. A method for suppressing and preventing carburizing and metal dusting, wherein a surface strain is preliminarily applied to a cast material contacted by a carburizing gas in a plant constituent device by one of a grinding process and a shot peening process. .