JP2003161434A - Combustion furnace with a furnace wall lined with corrosion resistant heat resistant cast steel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustion furnace having the high clinker preventive function, having high strength at a high temperature, and using high oxidation resistant, corrosion resistant, and heat resistant cast steel in a furnace wall having a structure of an inorganic fire resistant heat insulating material lined with corrosion resistant heat resistant steel. <P>SOLUTION: The furnace wall has the structure of the inorganic fire resistant heat insulating material lined with the corrosion resistant heat resistant steel. The corrosion resistant heat resistant cast steel is characterized by the composition composed of 0.10 to 0.40 wt.% of carbon, 18 to 26 wt.% of Cr, 0.5 to 6.0% of Ni, 1.5 to 5.5 wt.% of Al, 0.5 wt.% or less of Mn, 2.5 wt.% or less of Si, and a residual part of Fe substantially. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a furnace wall having a structure in which a corrosion-resistant heat-resistant steel is lined in an inorganic refractory heat insulating material, and a corrosion-resistant heat-resistant cast steel having a high clinker prevention function and high strength at high temperature is used for the furnace wall. Relating to a lined combustion furnace.

[0002]

2. Description of the Related Art In a waste incinerator that incinerates waste such as municipal solid waste to reduce its volume, and at the same time recovers energy and useful resources, components such as plastics that increase the combustion temperature have recently been treated. Further, in order to suppress the production of harmful substances such as dioxins generated by combustion, it is necessary to control the combustion temperature to operate at a high temperature. Due to these factors, in the internal structure of the incinerator, various problems have occurred in the conventionally used heat-resistant and high-temperature corrosion-resistant furnace wall material.

FIG. 3 shows a stoker-type incinerator 41 as an example of the waste incinerator. The waste 45 is supplied from the charging hopper 50, and comes into contact with the primary air 46 on the stoker 43 to burn and thermally decompose. Further, the vaporized combustion components come into contact with the secondary air 47 in the secondary combustion section 44 and are further burned, and the high temperature combustion exhaust gas is radiated by the heat recovery section 49 and discharged to the outside. The combustion residue (ash) falls into the receiving tank 48 and is taken out. Here, 42 is a furnace wall, which is composed of a fireproof / heat insulating material and a structural material that supports it.

FIG. 2 is an overall view showing the furnace wall of the stoker type combustion furnace. Reference numeral 31 is a part of the hopper, to which waste fuel is supplied, and is sent inside by a pusher 32 provided at the lower part of this part. Reference numeral 33 is a combustion section that burns on the stoker. Reference numeral 44 is the above-mentioned secondary combustion portion, and 34 is an ash extraction portion from which still high temperature ash falls. Reference numeral 5 is a refractory material that constitutes the furnace wall, and although not shown, it is supported by a structural material and is inside (on the fire side) via a heat insulating material.
Affixed to. This refractory insulation varies depending on the temperature inside the furnace, but the most fire-resistant, clinker-resistant, and highly heat-conductive material is silicon carbide ceramic brick. Even with this, the consumption of the brick due to oxidation is severe, and corrosion of 10 mm to 40 mm is observed in several months.

When the combustion temperature exceeds 1000 ° C., the clinker (ash) produced by the combustion is melted, and the reaction is adhered and deposited on the surface of the furnace wall. This phenomenon is most noticeable near the melting point of the clinker, and above that, the oxidative wear of the furnace material itself becomes more severe. These phenomena may make operation impossible due to the growth of deposits, which causes obstacles such as faster consumption of refractory materials. Furthermore, such problems as a decrease in operating rate and an increase in maintenance costs have been brought about by stopping operation and repairing.

[0006] In order to improve these, a furnace wall structure is lined with a cast steel plate that does not adhere to clinker and does not grow, but the cast steel material used therefor has not always been found to be satisfactory. There is a strong demand for a casting material having high clinker adhesion performance, corrosion resistance, and high strength.

For example, in Japanese Patent No. 2997869, the components are C: 0.1 to 0.4% by weight and Si: 0.2 to 1.2.
% By weight, Mn: 1.0-10.0% by weight, Cr: 22.
A heat-resistant cast steel material having 0 to 27.0% by weight, Ni: 3.0 to 6.0% by weight, the balance being substantially Fe, and Mn + Ni in the component being at least 6.0% by weight, which is suitable for the above-mentioned use. Is disclosed.

Further, Japanese Patent Laid-Open No. 2000-199621 discloses that
Ingredients: C: 0.05-0.4% by weight, Si: 0.1
2.0% by weight, Mn: 1.0 to 2.2% by weight, Cr: 2
2.0 to 28.0% by weight, Ni: 4.0 to 12.0% by weight, Al 0.3 to 1.5% by weight, the balance being substantially Fe and at least 28.0% by weight of Ni + Cr + Mn in the component.
The above heat-resistant cast steel materials and the like are disclosed as materials suitable for the above applications.

The technical idea of these heat-resistant cast steel materials is that by adding Mn to Ni / Cr heat-resistant and corrosion-resistant cast steel as a base, a basic oxide is formed by exposure to a high-temperature oxidizing atmosphere which is the use condition of the cast steel. It is said that Al2O3 having high resistance to oxidation and corrosion is generated by generating Al and adding Al. As a result, the basic clinker does not easily react with the surface of the cast steel containing the basic Mn oxide, and the Mn oxide is easily peeled off from the surface of the cast steel. I'm going to fall.

The applicant of the present application, on August 5, 1992, has another purpose of the incinerator, that is, various materials such as grate materials, nozzles, burners, etc., which are required to have heat resistance, corrosion resistance, and wear resistance. As a material for high temperature parts, its composition is C: 0.8-2.
0% by weight, Cr: 15.0 to 30.0% by weight, A1.
5 to 5.0% by weight, Si: 1.0 to 4.0% by weight, N
i: 0.5 to 6.0% by weight, rare earth metal: 0.01 to
We applied for a heat-resistant cast steel material with 0.5% by weight and the balance being substantially Fe, and obtained the patent No. 2923130.

The present inventors have reexamined these conventional heat-resistant cast steel materials, and have tried to develop a casting material which has a higher clinker adhesion preventing performance and is also suitable for corrosion-resistant and high-strength furnace wall coating material. , Carried out an earnest research.

In the first place, in order to study the mechanism of clinker exfoliation and oxidative corrosion resistance of the above-mentioned prior art, when the target cast steel was exposed to a high heat / high corrosive atmosphere in a furnace, oxides were formed on the surface of the cast steel alloy. Layers generate. FIG. 4 is a schematic diagram illustrating the situation, but the oxide layer on the cast steel alloy 1 is composed of two layers. The surface layer is a relatively brittle, oxide layer 5 made of an oxygen permeable oxide and made of Fe2O3, M
It is an unstable substance having a low density and rich in nO, and has a property of collapsing and peeling off when the clinker 8 is fused. On the other hand, the oxide layer 6 is a layer containing Cr2O3, Al2O3, SiO2, etc., and is expected to exhibit a protective function because it is impermeable to oxygen.
Was characteristically contained in a relatively large amount of 1.0 to 10.0% by weight or 1.0 to 2.2% by weight. When such a large amount of Mn is present, a large amount of MnO is also generated in the oxide layer 6 of FIG. 4 as indicated by reference numeral 7, so that the oxide layer 6 becomes extremely porous. Therefore, since the adhesion strength of the film is lowered, when the clinker adheres and the layer 6 also falls off when peeled off, the clinker adhesion preventing function is improved, but this layer 6 that is expected to be impermeable to oxygen disappears. Oxidation and corrosiveness is remarkably reduced in the part. In addition, the porous physical characteristics of the layer 6 itself deteriorate the dense protection property and increase the oxygen permeability, so that the function of preventing oxidative corrosion is deteriorated and the wear due to oxidative corrosion becomes severe. That is, when used as a lining material for an incinerator, the rate of wear is remarkable.

[0013]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above conventional problems, and has a high clinker prevention function in a furnace wall having a structure in which a corrosion resistant heat resistant steel is lined with an inorganic refractory heat insulating material, An object of the present invention is to provide a combustion furnace characterized by using a corrosion resistant heat-resistant cast steel having high strength at high temperature and high oxidative corrosion resistance.

[0014]

In a combustion furnace of the present invention, in a furnace wall having a structure in which a corrosion-resistant heat-resistant steel is lined with an inorganic refractory heat insulating material, the corrosion-resistant heat-resistant cast steel is carbon; 0.10 to 0.4.
0% by weight, Cr; 18 to 26% by weight, Ni; 0.5 to
6.0%, Al; 1.5 to 5.5% by weight, Mn; 0.5
It is characterized in that the composition is such that weight% or less, Si; 2.5 weight% or less, and the balance substantially Fe.

An essential requirement for a furnace wall lining material suitable for the purpose of the present invention is that the clinker physically fused to the surface is caught by the outermost layer of the film, and the film becomes brittle, so that the film is collapsed and peeled off. That is, the high-temperature oxygen is blocked by the dense oxygen-impermeable oxide film of the second layer, and further, it has a protective function of preventing the internal alloy from being attacked. In addition, at a high temperature of more than 1000 ° C., the lining material plate using the material is provided with strength and toughness that are not easily deformed even when exposed to some thermal stress.

The inventors of the present invention sought and studied a composition satisfying these requirements and arrived at the cast steel alloy composition of the present invention. That is, it was found that the first layer indicated by reference numeral 5 in FIG. 4 which has a clinker adhesion preventing function can sufficiently exfoliate the clinker due to the structure of Fe2O3. The concentration of Mn, which causes disadvantages, is suppressed as much as possible, but the concentration is such that the benefit of imparting alkalinity to the film remains.

The amount of C is appropriate within the range of the present invention in order to maintain high temperature toughness, and Ni and Cr have the basic composition as heat resistant / corrosion resistant steel. A further feature of the present invention is that the ratio and content of Al and Si are adjusted, whereby the oxygen impermeability of the film made of oxides of Al, Si, and Cr in the second layer is greatly improved. And increased high temperature strength.

Further, in the combustion furnace of the present invention, in the furnace wall having a structure in which an inorganic refractory heat insulating material is lined with a corrosion resistant heat resistant steel, the corrosion resistant heat resistant cast steel is carbon; 0.10 to 0.40% by weight, C
r; 18 to 26% by weight, Ni; 0.5 to 6.0%, A
l; 1.5 to 5.5% by weight, Mn; 0.5% by weight or less,
Si; 2.5 wt% or less, rare earth metal; 0.1 to 0.4
The composition is characterized in that the composition is composed of wt% and the balance is substantially Fe.

Furthermore, the addition of a rare earth element has the effect of increasing the high temperature strength, and Nb or Ta is particularly preferable.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to examples. However, the dimensions, shapes, materials, relative positions, etc. of the products described in the present embodiment are not intended to limit the scope of the present invention thereto unless otherwise specified, and are merely illustrative examples. Absent.

(Production of test material) Examples 1 to 3 and Comparative Example 1
In order to obtain the test material of ~ 3
It was manufactured by casting in a mold of kg. The test material was heat-treated by holding it at 1150 ° C. for 24 hours. As a result of analysis, the chemical composition of the obtained sample was the percentage shown in Table 1.

[0022]

[Table 1]

Examples 1 to 3 of the test materials in the above table are cast steel alloys having the composition of the present invention, in which the ratio and content of Al and Si are changed, and Comparative Example 1 is a prior art example. , A composition disclosed in Japanese Patent No. 2997869 with reduced C and Si contents, Comparative Example 2 is a prior art example,
It is the patent No. 2997869 itself. In Comparative Example 3, a conventional heat-resistant Ni-Cr cast steel was added with an amount slightly exceeding the upper limit of the Mn content of the present invention.

(Manufacturability test) In casting the test material,
The presence or absence of defects in the obtained ingot was inspected by visual inspection, and the results are shown in Table 2.

[0025]

[Table 2]

(High Temperature Corrosion Test) (1) A test piece of a high temperature oxidative corrosion test material was dried in air at a temperature of 900 ° C. and 1000 ° C.
The increase in weight was measured by holding at four stages of 1 ° C, 1100 ° C and 1200 ° C for 200 hours. The results are shown in Table 3. (2) The test piece of the high temperature chlorinated corrosion test material was buried in the actual ash and the atmosphere in the atmosphere was changed to HC.
1 at 550 ° C as an acidic atmosphere with a concentration of 1000 ppm
The weight loss was measured by holding for 00 hours. The results are shown in Table 3.
Shown in. (3) The test piece of the high-temperature sulfide corrosion test material was embedded in synthetic ash, the atmosphere was kept as dry air at 900 ° C. for 100 hours, and the weight reduction amount was measured. The results are shown in Table 3.

[0027]

[Table 3]

(Reactivity with Clinker, Peelability Test) On the furnace wall of the test plant, an inner lining plate having a structure to be described later was applied to each of the test materials, a test was carried out for 50 hours, and the results were observed. The exposure temperature was approximately 1200 ° C.
The results are shown in Table 4.

[0029]

[Table 4]

(Fracture toughness) A Charpy impact test piece was prepared by providing a 2 mm V notch on a plate material having a specified size cut out from a test material, and an impact fracture test was carried out at 0 ° C and 600 ° C.
The results are shown in Table 5.

[0031]

[Table 5]

(Comparative Examination) Examples 1 to 3 in the high temperature corrosion test
All of the test materials are 900 ° C. higher than the test materials of Comparative Examples 1 to 3.
The results were remarkably excellent under all other conditions except the oxidation test in dry air. In addition, the clinker reactivity and the peeling property were excellent in all three examples of the examples in spite of the reduced Mn, indicating that the peeling effect of Fe2O3 was sufficient. Further, in terms of fracture toughness, the composition having an extremely large amount of Al showed inferior numerical values even in the examples, but other than that, the toughness at high temperature (600 ° C.) was superior to the comparative example.

(Example of Construction of Furnace Wall of Test Plant) FIG. 1 shows an example of construction of a furnace wall having a structure in which a corrosion-resistant heat-resistant steel is lined in an inorganic refractory heat insulating material which is a combustion furnace of the present invention. Cast corrosion-resistant heat-resistant steel of each example. The (test material) was lined with a fireproof heat insulating material as shown in the figure. Corrosion resistance heat resistant steel plate 1 is approximately 350 x 240 mm
The test material is a cast steel plate having a size of 30 mm and a thickness of 30 mm. Counterbores for fixing means as shown in the above figure are made at the four corners of this rectangular plate, and as shown in the following figure, the inside of the refractory heat insulating material 3 is abutted to allow the bolt 2 to penetrate through the pipe 9 to the support structure 4 and the nut. I crimped it and fixed it.

[0034]

As described in detail above, according to the present invention, in a furnace wall having a structure in which a corrosion resistant heat-resistant steel is lined with an inorganic refractory heat insulating material, it has a high clinker preventing function and high strength at high temperature and high oxidation resistance. It has become possible to provide a combustion furnace characterized by using corrosive, corrosion-resistant, heat-resistant cast steel.

[Brief description of drawings]

FIG. 1 is a plan view and a cross-sectional view showing a construction example of a furnace wall having a structure in which a corrosion-resistant heat-resistant steel is lined in an inorganic refractory heat insulating material which is a combustion furnace of the present invention.

FIG. 2 is an overall schematic view showing a furnace wall of a stoker type combustion furnace.

FIG. 3 is a conceptual diagram of a stoker incinerator.

FIG. 4 is a schematic diagram illustrating how a clinker adheres and how oxygen permeates.

[Explanation of symbols]

1 Corrosion resistant heat resistant steel plate 2 volt 3 Fireproof insulation 4 Support structure 5 Oxide layer 6 Oxide layer 7 MnO 8 clinker 9 pipes Part of 31 hopper 32 pushers 33 Stalker 34 Ash outlet 41 stoker incinerator 42 Furnace wall 43 Stalker 44 Secondary combustion section 45 waste 46 primary air 47 Secondary air 48 receiving tank 49 Heat recovery unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F27D 1/00 F27D 1/00 D (72) Inventor Hiroshi Nishimura 5-4-6, Shiba, Minato-ku, Tokyo F term in Mitsubishi Heavy Industries Environmental Engineering Co., Ltd. (reference) 3K065 AA01 AB01 AC01 BA09 FA02 FA12 FB13 FC06 4K051 AA00 AB03 BB00

Claims (3)

[Claims] 1. In a furnace wall having a structure in which a corrosion-resistant heat-resistant steel is lined with an inorganic refractory heat insulating material, the corrosion-resistant heat-resistant cast steel is carbon; 0.10 to 0.40 wt%, Cr; 18 to 26 wt%, Ni; 0. 0.5 to 6.0%, Al; 1.5 to 5.5% by weight, Mn; 0.5% by weight or less, Si; 2.5% by weight or less, and the balance being substantially Fe. Combustion furnace with corrosion resistant heat resistant cast steel lined inside the furnace wall. 2. In a furnace wall having a structure in which a corrosion resistant heat resistant steel is lined with an inorganic refractory heat insulating material, the corrosion resistant heat resistant cast steel is carbon; 0.10 to 0.40 wt%, Cr; 18 to 26 wt%, Ni; 0. 0.5-6.0%, Al; 1.5-5.5% by weight, Mn; 0.5% by weight or less, Si; 2.5% by weight or less, rare earth metal; 0.1-0.4% by weight A combustion furnace having a furnace wall lined with corrosion-resistant heat-resistant cast steel, the balance of which is substantially Fe. 3. A combustion furnace in which the corrosion-resistant heat-resistant cast steel is lined in a furnace wall, wherein the rare earth metal is Nb or Ta.