JP2002267120A - Method for repairing surface of material of molten part of waste burnt ash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a life of a furnace by repairing by using a high corrosion resisting material when the heat resisting material of a molten part of which the inner wall surface of a furnace is formed is damaged by molten slag, in a melting furnace to produce molten slag by heating burnt ash of a burning substance containing waste. SOLUTION: In a fire-resisting material 1 of which the inner surface of the molten part of a melting furnace where waste burnt ash is heated to form molten slag is formed, when the surface of the material 1 is damaged by the molten slag 2, a mixture material consisting of a spinel type compound MCr2 O4 (M is Mg or bivalent Fe) or a mixture material consisting of the compound, chromia, and zirconia are used as a repair material 4 and repair is effected by a spraying method. The spinel type compound, chromia, and zirconia are all thermodynamically stable, and high in compatibility with alkali and sulfur and corrosion of a heat resisting material can be suppressed by ash molten slag containing the elements in high concentration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to industrial waste such as waste (general waste such as municipal waste from homes and offices, waste plastic, car shredder dust, waste office equipment, electronic equipment, cosmetics, etc.). And ash produced by incineration of flammable substances (including combustibles) by heating to form a molten slag.

[0002]

2. Description of the Related Art As an example of an apparatus for treating general waste such as municipal solid waste and combustibles such as waste plastics, the waste is put into a thermal decomposition reactor and heated under a low oxygen atmosphere. The pyrolysis gas (pyrolysis gas) and a pyrolysis residue mainly composed of non-volatile components are generated, the pyrolysis gas and the pyrolysis residue are separated in an exhaust device, and the pyrolysis residue is further purified. After cooling with a cooling device under an active atmosphere, it is supplied to a separation device and separated into a combustible component mainly composed of pyrolytic carbon and a non-combustible component such as metal, pottery, and gravel. Pulverized into a powder, the pulverized combustible component and the pyrolysis gas are introduced into a combustion melting furnace to be burned, and the resulting combustion ash is heated by the combustion heat to form a molten slag. Along the inner surface of the furnace covered with refractory material Beat, waste disposal apparatus that is cooled and solidified was discharged to the outside through the discharge unit is known (see Japanese Patent Kokoku 6-56253).

[0003] The high-temperature flue gas (about 1200 ° C) generated in the combustion melting furnace is recovered heat energy by a heat exchanger provided at the subsequent stage, further collected by a dust collector, and finally cleaned up. And released into the atmosphere from the chimney.

[0004] In industrial kilns, boilers, waste incinerators, and the like that require high-temperature treatment, such as steel, non-ferrous, cement, glass, and ceramics, refractories and ceramics with high heat resistance are used. In the use in an environment that comes into contact with the molten slag, it is necessary to consider severe high-temperature corrosion involving the molten slag as well as the gas phase environment such as the oxygen partial pressure and the alkali partial pressure.

In general, when the oxygen partial pressure is high,
Oxide-based heat-resistant materials are used. As a guide for selecting corrosion resistance, a basic material is used when the slag basicity is 1 or more, and a neutral or acidic heat-resistant material is used when the slag is 1 or less. . In the case of oxide-based heat-resistant materials from refuse incineration that burns and melts with air, slag basicity is often 1 or less,
A neutral heat-resistant material mainly composed of Al ₂ O ₃ is selected.

[0006]

As described above, molten slag obtained by melting waste combustion ash has a higher content of alkali elements such as Na and K than steelmaking slag and other molten materials. Therefore, Al ₂ O ₃ —SiO ₂ , A
l ₂ O ₃ -SiC, when the Si-containing refractory material such, either initially present or is generated SiO _2, reacts with an alkali in the ash molten slag, alkali silicate having a low melting point is generated.

[0007] Since this compound is fluidized, the thickness of the refractory gradually decreases. On the other hand, in the case of a high Al ₂ O ₃ refractory material or ceramics, it reacts with components such as alkali, sulfur and chlorine in the ash molten slag to lower the melting point. Therefore, the life of the refractory material or ceramics is shortened.

SUMMARY OF THE INVENTION An object of the present invention is to provide a melting furnace in which a combustion ash component of a combustion product including waste is heated to form a molten slag. To provide a repair method in the event that it occurs.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a material for melting a waste combustion ash which constitutes a furnace inner surface of a furnace which heats the combustion ash of a combustion product containing the waste into molten slag. On the surface, the surface is treated with a spinel-type compound (Mg _1-α Fe _σ ) _β (Cr _1-γ-σ Al _γ F
e _σ ) ₂ O _{4 is} repaired by a spraying method as a repair material.

According to the above-mentioned repair method, when the ash is heated (about 1300 ° C.) to form a molten slag, the surface of the member that comes into contact with the slag is constructed of a spinel type compound. , Can avoid severe erosion.

[0011] Cr ₂ O ₃ has a large surface tension with molten slag and is hardly wet. Therefore, penetration of the molten slag is suppressed. Cr ₂ O ₃ increases the viscosity of the liquid phase upon dissolution in the molten slag. Therefore, the mass transfer rate in the slag boundary phase in contact with the heat-resistant material is reduced. Since Cr ₂ O ₃ alone is an acidic oxide, its solubility in alkali-containing slag tends to be high. However, a spinel-type substance that is an equimolar compound with a basic oxide such as MgO. When constituted, the solubility in the alkali-containing slag is suppressed.

A typical example of a spinel compound having such properties is picrochromite MgCr ₂ O.
₄ and chromite FeCr ₂ O ₄ . At this time, the molar ratio between MO and Cr ₂ O ₃ in the spinel type compound is
The ratio does not need to be 1: 1 (constant ratio), and a spinel structure can be formed when the ratio of Cr ₂ O ₃ is in the range of 50 to 58 mol% by analogy with the case of MgO.nAl ₂ O ₃ at 1300 ° C. Specificity). This ratio corresponds to 0.714 ≦ β ≦ 1 in the expression of M _β Cr ₂ O ₄ .

Here, the metal element M at the 4-coordinate position in the spinel structure may be either Mg or divalent Fe, or a mixed state of the two at an arbitrary ratio.
Further, as the metal element at the 6-coordinate position in the spinel structure, at least half or more are Cr, and the remainder is Al or trivalent Fe. Such a spinel-type compound in which Cr at the 6-coordinate position occupies half or more can effectively suppress erosion by molten slag containing a high concentration of an alkali element in both stoichiometric and nonstoichiometric compounds.

Further, the present invention provides the spinel type compound
Not only one phase but also a corundum type compound (Cr
_1-ε-ζAl_εFe_ζ)₂O₃(However, 0 ≦ ε, 0
≦ か ら, 0 ≦ ε + ζ <0.5)
It is characterized by repairing by spraying method using the material as repair material
And The corundum type compound is used near the operating surface during use.
Reacts with the MO component in the raw material waste to produce spinel-type compounds
M_β(Cr_1-γ-δAl _γFe_σ)₂O₄Produces
As a result, the corrosion resistance of the member is improved.

Further, the present invention is characterized in that not only the spinel-type compound single phase but also a material consisting of a two-phase mixture of the spinel type compound and zirconia is repaired by a spraying method as a repairing material. When the surface is repaired in this way, when the ash is heated (about 1300 ° C.) to form a molten slag, a member that comes into contact with the slag is covered with the Cr-containing spinel-type compound and zirconia to avoid severe erosion. it can.

Further, the present invention provides not only a single phase of the spinel type compound but also a corundum type compound COR.
-Phase mixture (1-η-θ) · S with zirconia ZR
P + η · COR + θ · R (where 0 <η <1, 0 <θ
It is characterized in that the material composed of <0, 5) is repaired by a spraying method as a repair material.

[0017] By such a repair, the effects of the second and third aspects are superimposed, and as a result, the durability of the member is improved. However, if the proportion of the added zirconia exceeds 50% by weight, the zirconia is combined with various silicates in the molten slag, and the durability is lowered.

Further, the present invention is characterized in that the repair material contains 40% by weight or less of metallic Cr in a non-oxidized state. During use, near the operating surface, the metal Cr reacts with the MO component in the raw material and oxygen in the gas phase to generate the spinel compound MCr ₂ O ₄ , thereby improving the corrosion resistance. However, if the Cr metal powder to be added exceeds 40% by weight of the whole composition, the local expansion may increase due to an oxidation reaction during use, so the content is set to 40% by weight or less.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Test Example 1 As shown in FIG.
As Example 1, a repair material 4 having a thickness of 10 mm was formed by spraying a single phase of picrochromite on the surface of a refractory material 1 composed of alumina-chromia. This repair material 4 was examined for its protection against the reaction with the molten slag 2 such as ash and the reduction of the wall thickness under the environment of the corrosive gas 3 simulating the melting part of the refuse incinerator.

As Comparative Example 1, N ₂ + 5% was used for a test piece having a repair material obtained by repairing the surface of a refractory made of alumina-chromia by a spraying method using an alumina-chromia material and the test piece of Example 1 above. O ₂ +1000 ppm HC
I was immersed in ash molten slag at 1450 ° C. for 20 hours under 1 atmosphere to give corrosion wear. After the test, the amount of erosion was measured and compared.

Table 1 shows the results. Table 2 shows the chemical composition of the ash molten slag. According to these, the test piece having the repair material repaired by the spraying method using the spinel type compound according to the present invention has a higher ash content generated by refuse incineration than the test piece having the repair material repaired by the spraying method using the alumina-chromia material. In an environment in which slag was heated to form a molten slag, the amount of wall thinning in Example 1 was not more than 1/5 of that in Comparative Example 1, and it can be seen that it was excellent in corrosion resistance.

[0022]

[Table 1]

[0023]

[Table 2]

It is to be noted that metal Cr is added to the surface repairing member.
The same erosion test was performed with 0% by weight mixed.
Metal Cr near the surface was changed to Cr ₂ O ₃ or spinel type compound MCr ₂ O ₄ .

<Test Example 2> As Example 2, alumina-
A mixture of picrochromite and 5% of chromia and 15% of zirconia was added to the surface of a refractory material made of chromia and sprayed in the same manner as in FIG.
And a test piece having the repair material repaired by the spraying method using the same alumina-chromia material as in Comparative Example 1 was subjected to corrosion and wear in the same manner as in Test Example 1. And the amount of erosion was measured and compared. Table 3 shows the results. Example 2 was slightly as small as 0.9 mm in comparison with the thickness reduction of 6.5 mm in Comparative Example 1, indicating that sufficient corrosion resistance was obtained.

[0026]

[Table 3]

Next, the operation will be described. Spinel-type compounds,
M_β(Cr_1-γ-δAl_γFe_σ) ₂O₄, And di
Ruconia refractories are thermodynamically stable and
Since it is highly compatible with re-elements, it is produced in a combustion melting furnace.
Erosion due to this type of molten slag can be suppressed. Also,
The addition of luconia improves the sinterability of Cr-containing compounds
You. Therefore, the durability of the repair material is improved, and
The operation efficiency of the material processing apparatus can be improved.

In Example 1, the protective layer was formed of a spinel compound, M _β (Cr _{1 -γ - δ} Al _γ Fe _σ ) _{2 from the beginning.}
Although the one formed of O ₄ has been described, even if the spinel-type compound is not formed at first, a material containing Cr ₂ O ₃ is used as the protective layer, and the M
g or Fe may be added so that the spinel-type compound is generated simultaneously with the generation of the molten slag.

[0029]

According to the present invention, there is provided a melting furnace for heating combustion ash of a combustion product including waste to form a molten slag.
Damage to the furnace wall due to the molten slag of the molten material constituting the furnace inner surface is repaired by spraying a Cr-containing spinel compound or a mixture of this compound and components such as chromia and zirconia by spraying. It is possible to extend the life of the battery.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of repairing the surface of a melting furnace according to the present invention.

[Explanation of symbols]

 1 Refractory materials such as ceramics 2 Molten slag 3 Corrosive gas 4 Repair materials

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F27D 1/00 F27D 1/00 N 1/16 1/16 A (72) Inventor Masakata Hashimoto Tamano, Okayama 3-1-1 Ichitama Mitsui Engineering & Shipbuilding Co., Ltd. Tamano Works Co., Ltd. F-term (reference) 3K061 AA24 AC01 AC13 BA01 NB28 3K065 AA11 AB03 AC01 AC03 BA05 4G033 AA01 AA02 AA07 AA09 AB09 BA02 4K051 AA00 AB03 BE01 LA11

Claims (5)

[Claims] 1. A spinel type compound SP represented by the following formula (1) is provided on a surface of a molten material constituting an inner surface of a melting furnace for generating a molten slag by heating a combustion ash of a combustion product including a waste. A method for repairing the surface of a molten material of a waste combustion ash, which comprises spraying the repaired material as a repair material. (Equation 1) 2. A spinel-type compound SP represented by the following formula (1) is provided on a surface of a molten portion material constituting an inner surface of a melting furnace which generates a molten slag by heating a combustion ash of a combustion product including a waste. , A corundum type compound C represented by the following formula (2):
Two-phase mixture with OR (1-η) .SP + η.COR
A method for repairing the surface of a molten material of a waste combustion ash, wherein a material comprising (0 <η <1) is sprayed as a repair material to repair the material. (Equation 2) 3. A spinel-type compound SP represented by the following formula (1) is provided on a surface of a molten portion material constituting an inner surface of a melting furnace for generating a molten slag by heating a combustion ash of a combustion product including a waste. A method for surface treatment of a molten material of waste combustion ash, which comprises spraying a material consisting of 0.1 to 50% by weight of zirconia as a repair material to repair the material. (Equation 3) 4. A spinel-type compound SP represented by the following formula (1) is provided on a surface of a molten portion material constituting an inner surface of a melting furnace for generating a molten slag by heating a combustion ash of a combustion product containing waste. , A corundum type compound C represented by the following formula (2):
Three-phase mixture of OR and zirconia ZR (1 + η-θ)
SP + η COR + θ ZR (where 0 <η <1,
0 <θ <0.5). A method for repairing the surface of a molten material of a waste combustion ash, comprising spraying a material comprising 0 <θ <0.5) as a repair material. (Equation 4) 5. The method of claim 1, wherein the repair material contains 40% by weight or less of metallic Cr in a non-oxidized state. A method for repairing the surface of ash melted parts.