JPH1183000A - Materials for melting part of waste combustion ash - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To provide a ash melting slag of a member for a melting portion of a waste combustion ash constituting a furnace inner surface constituting a furnace inner surface by heating an ash generated by burning a combustion material based on the waste to form a molten slag. To improve corrosion resistance against SOLUTION: A member for a melting portion of a waste combustion ash constituting an inner surface of a furnace which heats an ash generated by burning a combustion material based on a waste to form a molten slag, wherein the melting portion member is a spinel. It is characterized by comprising a refractory material of a type compound MCr ₂ O ₄ (M is Mg or divalent Fe).
Since the spinel-type compound refractory is thermodynamically stable and highly compatible with an alkali element, erosion of the refractory by molten slag containing the alkali element from the beginning can be suppressed.

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.). Etc., a member for the melting part of waste combustion ash constituting the inner surface of a melting furnace which forms slag by heating ash generated by incineration of a material containing a combustible material, a method of reforming the member and a waste treatment apparatus It is about.

[0002]

2. Description of the Related Art As one of treatment apparatuses for waste including general waste such as municipal solid waste and combustibles such as waste plastics, the waste is put into a thermal decomposition reactor and heated in a low oxygen atmosphere to heat the waste. Decomposes to generate a pyrolysis gas (dry distillation gas) and a pyrolysis residue mainly composed of non-volatile components. The pyrolysis gas and the pyrolysis residue are separated in a discharge 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 above-mentioned pyrolysis gas are introduced into a combustion melting furnace and burned, and the resulting combustion ash is heated by the combustion heat to form a molten slag, and the molten slag is formed. The slag flows along the inner surface of the furnace covered with refractory material. And, waste is discharged to the outside so as to cool and solidify processing apparatus is known from the discharge portion (KOKOKU 6-56253 Patent Publication). The high-temperature flue gas (approximately 1200 ° C.) generated in the combustion melting furnace is recovered heat energy by a heat exchanger provided at the subsequent stage, and is further collected by a dust collector, and finally becomes clean exhaust gas. From the chimney. Refractories are used in industrial kilns, boilers, waste incinerators, etc. that require high-temperature treatment, such as steel, non-ferrous, cement, glass, and ceramics. In use in an environment that comes into contact with molten slag, it is necessary to consider severe high-temperature corrosion involving the molten slag as well as the gas-phase environment such as oxygen partial pressure and alkali partial pressure. In general, when the oxygen partial pressure is high, an oxide refractory is used.
In the above case, a basic refractory is used. In the case of 1 or less, a neutral or acidic refractory is used. In the case of oxide refractories in incineration of refuse which is burned and melted with air, the slag basicity is often 1 or less, and a neutral refractory mainly composed of Al ₂ O ₃ is selected.

[0003]

The molten slag obtained by melting the above ash has a higher content of alkali elements such as Na and K than steelmaking slag and other molten materials. Therefore, in the case of a Si-containing refractory material such as Al ₂ O ₃ —SiO ₂ and Al ₂ O ₃ —SiC, Si that is present or generated from the beginning
O ₂ reacts with the alkali in the ash molten slag to produce a low melting alkali silicate. Since this compound is fluidized, the refractory material gradually loses its thickness. On the other hand, in the case of an Al ₂ O ₃ refractory material or ceramics, so-called β-alumina is formed, and the melting point is lowered. Therefore, the life of the refractory material is shortened.

[0004] It is an object of the present invention to provide a ash melting slag of a member for a melting portion of a waste combustion ash which constitutes a furnace inner surface which forms a furnace slag by heating an ash generated by burning a combustion product based on the waste. The purpose is to improve the corrosion resistance to corrosion.

[0005]

In order to achieve the above-mentioned object, the invention according to claim 1 of the present invention comprises an inner surface of a furnace which heats ash generated by burning a combusted material based on waste to form a molten slag. The member for the melting portion of the waste combustion ash is characterized in that the member for the melting portion is made of a spinel-type compound represented by the following formula (1).

[0006]

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When the ash is heated (about 1300 ° C.) to form a molten slag, the member that comes into contact with the slag is made of a Cr-containing spinel type compound.
The following effects can prevent severe erosion. Cr ₂ O ₃ has a large surface tension with the 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 layer in contact with the refractory material decreases. Cr ₂ O ₃ alone tends to have a high solubility in alkali-containing slag because of its nature as an acidic oxide, but a spinel-type substance that is an equimolar compound with a basic oxide such as MgO is used. With this configuration, the solubility in the slag containing alkali does not increase so much.

[0008] Representative examples of the spinel-type compound substance having such properties include 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 does not need to be 1: 1 (constant ratio), but MgO · nAl ₂ O _{3 at} 1300 ° C.
By analogy with the above case, the ratio of Cr ₂ O ₃ is 50 to 58 mol%.
Can form a spinel type structure (nonstoichiometric). In the case of the following equation (4), this ratio is 0.714 ≦ β ≦ 1
Is equivalent to 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 both in an arbitrary ratio.

[0009]

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[0010] Further, as the metal element at the 6-coordinate position in the spinel structure, at least half or more are Cr and the rest are A
Let it be 1 or trivalent Fe. The spinel-type compound in which Cr in the six-coordinate position occupies more than half of the stoichiometric compound effectively suppresses erosion by molten slag containing a high concentration of an alkali element in both the stoichiometric and nonstoichiometric compounds for the above-mentioned reason. it can.

The invention of claim 2 of the present application is directed to the invention of claim 1, wherein not only the spinel-type compound single phase but also
As the member for the fusion zone, the spinel-type compound SP and a corundum-type compound COR represented by the following formula (2) are used.
Phase mixture (1-η) · SP + η · COR (where 0 <
η <1.0). Corundum type compound COR, chromium oxide alone, chromium oxide-rich chromium oxide-aluminum oxide solid solution, and the like are included. The corundum type compound reacts with the MO component in the raw material refuse in the vicinity of the operating surface during use, generates a compound represented by the following formula (3), and improves corrosion resistance.

[0012]

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[0013]

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[0014] The invention according to claim 3 of the present invention relates to the application of the present spinel type compound as, for example, an amorphous refractory.
A means for improving the sinterability of the matrix portion is provided. That is, a refractory material close to the present system has been proposed (JP-A-9-71477).
The raw material is an electrofused refractory material, and fine powder indispensable for improving sinterability is difficult to obtain easily, and even if obtained, the cost is high. According to the method of this section, it is sufficient for the solid phase reaction,
Since a temperature at which sintering is not so strong can be selected, fine powder can be obtained at low cost by light pulverization.

[0015] The invention described in claim 4 of the present application is claim 1 or 2.
In the invention described above, as a material before use in the material for the fusion zone member, a material in which 5% by weight or more and 40% by weight or less of metal Cr are mixed is formed as a film on the surface of the metal member. I do. 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 amount of the Cr metal powder to be added is 40% by weight or more of the whole composition, local expansion may be increased due to an oxidation reaction during use, so the content is set to 40% by weight or less.
Further, when the content is 5% by weight or less, the film lacks conformability with a metal member and the film is easily peeled off. Thereby, the durability of the metal material as a structural member for supporting the refractory is improved by forming the molten slag corrosion resistant film on the surface.

According to a fifth aspect of the present invention, when the ash produced by burning a combustion product based on a waste is heated into molten slag, the divalent metal M or M is previously contained in the waste.
Was added containing compound represented by the following formula (3) (wherein M according to claim 1 or 2 is reacted with refractory material Cr ₂ O ₃ content constituting the melting furnace inner surface either Mg or a divalent Fe Or a mixed state of any ratio of the two), in particular, MCr ₂ O ₄ .

[0017]

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Further, the invention according to claim 6 of the present application is characterized in that when the ash produced by burning the combustion material based on the waste material is heated into molten slag, the waste material contains a divalent metal M or M 2 -containing compound is added, and Cr ₂ constituting the inner surface of the melting furnace
A method for reforming a member for a melting portion of waste combustion ash, which comprises reacting with a refractory containing O ₃ to generate a spinel-type compound represented by the above formula (3).

According to these inventions, when heating the ash to form a molten slag, the M component (Mg) added in advance is used.
Alternatively, Fe) reacts with the Cr ₂ O ₃ component in the refractory to form a spinel type compound (MCr ₂ O ₄ ) on the surface of the refractory, and acts as a protective film for the molten slag.

According to a seventh aspect of the present invention, there is provided a member for a melting portion of a waste combustion ash constituting an inner surface of a furnace which heats an ash generated by burning a combustion product based on the waste to form a molten slag. The material according to any one of claims 1 to 5 is characterized in that the material according to any one of claims 1 to 5 is used as a material for a protective material of a thermocouple which is provided at a portion of the member for the fusion zone and measures a temperature. Addition of a component other than Cr at the 6-coordinate position in the spinel-type compound represented by the following formula (5) makes the total amount of the additive element Al and trivalent Fe lower the amount of Cr so as not to impair the corrosion resistance. Do not exceed the range.

[0021]

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[0022] The invention according to claim 8 of the present application provides a pyrolysis reactor for pyrolyzing waste to produce a pyrolysis gas and a pyrolysis residue, and a cooling device for cooling the pyrolysis residue in an inert atmosphere. And a separation device for separating the cooled pyrolysis residue into a combustible component and a non-combustible component, and burning the pyrolysis gas and the combustible component at a temperature at which ash is melted to convert the non-combustible component into molten slag. In a waste treatment apparatus provided with a combustion and melting furnace discharged from a discharge unit and a heat exchanger that recovers heat of a high-temperature gas generated in the combustion and melting furnace by exchanging heat with air, the furnace inner surface of the combustion and melting furnace is removed. The constituent member is the member for a fusion zone according to any one of claims 1 to 5 or 7. Thereby, the durability of the combustion melting furnace is improved, so that the operation efficiency of the apparatus can be improved.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

It was molded by (Example 1) Cr ₂ O ₃ and MgO filled with powder in a mixing ratio of 79:21 in a weight ratio to the mold hydrostatic pressing method. The molded body was heated at 1600 ° C. for 5 hours in an air atmosphere. The obtained solid phase reaction product was confirmed to be picrochromite by X-ray diffraction. This was pulverized by an ordinary ball mill, classified, mixed with powders of various sizes together with a sintering aid, sulfamic acid, pressed and sintered to obtain a test body. Sintering was performed at 1700 ° C. for 3 hours.

A cube was cut out from this sintered body as a test sample, and the test piece was cut in a N ₂ + 5% O ₂ +1000 ppm HCl atmosphere.
After immersion in ash molten slag at 50 ° C. for 20 hours, the amount of erosion was measured. For comparison, an Al ₂ O ₃ sintered body and Al
Per ₂ O ₃ -SiC sintered body was subjected to erosion test under the same conditions. These experimental conditions simulate the molten slag environment of a refuse incinerator. Table 1 shows the obtained results. Table 2 shows the chemical composition of the ash molten slag. According to this, picrochromite MgCr ₂ O ₄ sintered body, which is a spinel-type compound having Cr at the 6-coordinate position, is made of Al ₂
It can be seen that, compared to the O ₃ sintered body and the Al ₂ O ₃ —SiC sintered body, the corrosion resistance is excellent even in an environment where the ash generated by incineration of the refuse is heated to form a molten slag.

[0025]

[Table 1]

[0026]

[Table 2]

On the surface of the iron member, a film was formed by spraying a mixture of picromite and 20% by weight of metal Cr, and an erosion test was carried out.
r was changed to Cr ₂ O ₃ or spinel type compound MCr ₂ O ₄ , and the corrosion resistance was good.

(Embodiment 2) Next, an example of a waste treatment apparatus provided with a member for a melting portion of waste combustion ash according to the present invention will be described with reference to FIG. In the waste treatment apparatus of the present embodiment, waste 50a such as municipal waste is crushed to a size of 150 mm square or less by, for example, a crusher such as a biaxial shearing method, and is charged into the charging section 50 by a conveyor or the like. Is done. The waste 50 a charged into the charging section 50 is supplied into the pyrolysis reactor 52 via the screw feeder 51. In this example, a horizontal rotary drum is used as the thermal decomposition reactor 52, and the inside of the thermal decomposition chamber in the drum is kept in a low oxygen atmosphere by a seal structure (not shown).

The waste 50a is thermally decomposed in the pyrolysis reactor 52, and its heat source is heated by a high-temperature air heater 1 which is a heat exchanger disposed downstream of a combustion melting furnace 53 described later. a heated air 8 g (heat medium) supplied through a heated air line L ₁ is. With 8 g of the heated air, the inside of the pyrolysis reactor 52 is maintained at 300 to 600 ° C., usually 450 ° C.
It is maintained at about ° C.

Furthermore, waste 50a heated by the heated air 8g is thermally decomposed to the pyrolysis gas G _1, becomes the pyrolysis residue 54 consisting mainly of non-volatile components, it is sent to the discharge device 55 Separated. The pyrolysis gas G ₁ separated by the discharge device 55 is supplied from above the discharge device 55 to the burner 56 of the combustion melting furnace 53 via the pyrolysis gas line L ₂ . Pyrolysis residue 54 discharged from discharge device 55
Is cooled to about 80 ° C. in an inert atmosphere by a cooling device 57 to be described later.

Thereafter, the cooled pyrolysis residue 54 is
For example, it is supplied to a known single or combined separation device 58 such as a magnetic separation type, an eddy current type, a centrifugal type or a wind separation type, where the fine combustible component 58d (including ash) and iron, rubble, etc. The non-combustible component 58c is separated into the non-combustible component 58c, and is collected and reused in the container 59.

Further, the combustible component 58d is mainly composed of pyrolytic carbon.
are milled below m becomes powder carbon, combustible component line L ₃ a via is supplied to the burner 56 of the burning melting furnace 53, pyrolysis gas G ₁ supplied from the pyrolysis gas line L ₂
It is burned in a high temperature range of about 1,300 ° C. with the supplied combustion air 61e from the air line L ₄ by the blower 61 and.

The ash generated by the combustion becomes molten slag 53f due to the heat of combustion, adheres to the inner wall of the combustion furnace 53, flows down the inner wall, and discharges the cylindrical discharge portion 71 from the bottom discharge port 62. Then, it falls into the water tank 63 and is cooled and solidified. The combustion melting furnace 53 includes a combustible component 58d such as carbon.
Is burned at a high temperature of about 1300 ° C., and the unburned portion including the ash is melted, and the molten slag 53f and the high-temperature flue gas G are melted.
₂ and generate Combustion exhaust gas G ₂ is, per second 2 to 3 m, so the temperature 1000 to 1100 ° C. in a gas stream, is heat recovered by the heat transfer tube of the hot air heater 1 provided in the furnace downstream.

Here, the combustion melting furnace is formed of the member for the melting portion of the waste combustion ash according to the present invention. In this example, it is formed of a spinel type compound refractory material. That is, the molten slag contains a high concentration of an alkali element such as Na or K, but is formed of a material having high corrosion resistance to the alkali element.

The flue gas G _{2 that} has passed through the high-temperature air heater 1 is recovered by a waste heat boiler 64 via a flue gas line L ₅ , removed by a dust collector 65, and further purified by an exhaust gas purifier. After harmful components such as chlorine are removed at 66, the exhaust gas G ₃ is discharged into the atmosphere from the chimney 68 via the induction blower 67 as clean low-temperature exhaust gas G ₃ . The steam generated by the waste heat boiler 64 is used for power generation by a generator 69 having a steam turbine. Part of the clean exhaust gas G ₃ is fan 7
0 is supplied to the cooling device 57 by a gas line L ₆ through.

Next, the operation will be described. Cr at 6 coordination position
Since the spinel-type compound refractory represented by the above formula (3) having thermodynamic stability is thermodynamically stable and has high compatibility with an alkali element, erosion due to this kind of molten slag generated in the combustion melting furnace 53 is suppressed. Can be suppressed. Therefore, the durability of the combustion melting furnace is improved, and the operation efficiency of the waste treatment device can be improved.

Although the combustion melting furnace was described in Example 2 as being made of a spinel-type compound refractory from the beginning, even if the spinel-type compound was not initially formed, Cr ₂ O was used as a refractory material. with those containing _3, possible to add the Mg and Fe in advance waste, may be simultaneously spinel compound producing a molten slag is produced.

In the above, the present invention has been described in detail with reference to the illustrated embodiments. However, the present invention is not limited to only those embodiments, and various modifications can be made without departing from the spirit of the present invention. It goes without saying that a wide variety of modifications can be made.

[0039]

According to the present invention, according to the present invention, the ash of the member for the melting portion of the waste combustion ash constituting the furnace inner surface which forms the furnace inner surface by heating the ash generated by burning the combustion material based on the waste to form a molten slag Corrosion resistance to molten slag can be improved.
In the present invention, the addition of a component other than Cr to the 6-coordinate position in the spinel-type compound has effects of increasing the ease of producing the present compound and reducing the production cost.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a waste disposal apparatus according to the present invention.

[Explanation of symbols]

 53 Combustion melting furnace 53f Molten slag

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F23G 5/46 ZAB F23G 5/46 ZABZ F23J 1/00 F23J 1/00 B // B09B 3/00 B09B 3/00 303D (72 ) Inventor Naoyuki Nishimura 3-1-1, Tamano, Tamano-shi, Okayama Mitsui Engineering & Shipbuilding Co., Ltd.

Claims (8)

[Claims] Claims: 1. A member for a melting part of a waste combustion ash constituting an inner surface of a furnace that heats an ash generated by burning a combustion material based on a waste to form a molten slag, wherein the member for a melting part is: A member for a melting part of waste combustion ash, comprising a spinel compound represented by the following formula (1). Embedded image 2. The two-phase mixture (1-η) of the spinel-type compound SP and a corundum-type compound COR represented by the following formula (2) as the member for a fusion zone.
A member for a melting portion of waste combustion ash, comprising SP + η · COR (where 0 <η <1.0). Embedded image 3. The spinel-type compound according to claim 1 or 2, synthesized from a single raw material or a composite raw material containing the constituent elements Mg, Fe, Cr, and Al by a solid-phase reaction,
A method for producing a member for a molten portion of waste combustion ash, which comprises pulverizing the powder, shaping and firing the powder. 4. The material according to claim 1, wherein 5% by weight of metal Cr is used as the pre-use state in the material of the member for the fusion zone.
A member for a melting portion of waste combustion ash, characterized in that a mixture of not less than 40% by weight is coated on the surface of a metal member as a film. 5. When heating the ash produced by burning the combustion material based on the waste material into molten slag, a divalent metal M or an M-containing compound is added to the waste material in advance, The following formula (3) according to claim 1 or 2 (where M is either Mg or divalent Fe, or both) by reacting with the refractory containing Cr ₂ O ₃ constituting the inner surface of the melting furnace. (A mixed state in an arbitrary ratio) is produced by producing a spinel-type compound represented by the formula (1): Embedded image 6. When heating the ash produced by burning the combustion material based on the waste material into molten slag, a divalent metal M or a compound containing M is added to the waste material in advance, A method for modifying a member for a melting portion of waste combustion ash, comprising reacting with a refractory containing Cr ₂ O ₃ constituting an inner surface of a melting furnace to generate a spinel-type compound according to claim 5. 7. A member for a melting part of a waste combustion ash constituting an inner surface of a furnace which heats an ash generated by burning a combustion material based on the waste to form a molten slag, the part of the member for the melting part A member for a molten portion of waste ash, characterized in that the material according to any one of claims 1 to 5 is used as a material of a protective material of a thermocouple provided in the thermocouple for measuring a temperature. 8. A pyrolysis reactor for pyrolyzing waste to produce a pyrolysis gas and a pyrolysis residue; a cooling device for cooling the pyrolysis residue in an inert atmosphere; A separation device for separating the decomposition residue into a combustible component and an incombustible component, and a combustion device in which the pyrolysis gas and the combustible component are burned at a temperature at which ash is melted, and the unburned component is discharged from a discharge portion as molten slag. In a waste treatment apparatus including a melting furnace and a heat exchanger that recovers heat of a high-temperature gas generated in the combustion melting furnace by exchanging heat with air, a member constituting a furnace inner surface of the combustion melting furnace is claimed. A waste treatment apparatus, which is a member for a fusion zone according to any one of 1 to 5 or 7.