JP2007131495A - Refractory material, and waste incinerating/melting furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refractory material improved in corrosion resistance to slag generated by incinerating and melting waste materials, and to provide a waste incinerating/melting furnace using the refractory material. <P>SOLUTION: The refractory material contacting the melted slag in a waste incinerating/melting furnace comprises 95-99 mass% of a refractory main material composed of aluminum oxide or zinc spinel and 5-1 mass% of a binder, and further includes potassium aluminate of 0.5-25 mass% in an external percentage as an additive. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention incinerates general waste such as municipal waste from homes and offices, industrial waste such as waste plastic, car shredder dust, electronic equipment and cosmetics, that is, waste containing combustibles. In particular, the present invention relates to a refractory material that constitutes an inner surface of a waste combustion melting furnace that heats the generated ash to form molten slag, and a waste combustion melting furnace that uses the refractory material for the inner wall of the furnace.

  As one of the processing equipment for waste including municipal solid waste and combustible waste such as plastic, waste is put in a pyrolysis reactor and heated in a low-oxygen atmosphere for thermal decomposition and thermal decomposition. Gas (dry distillation gas) and pyrolysis residue mainly composed of non-volatile components are produced, and the pyrolysis gas and pyrolysis residue are separated in a discharge device, and the pyrolysis residue is further removed under an inert atmosphere. After cooling with a cooling device, it is supplied to a separation device and separated into combustible components mainly composed of pyrolytic carbon, and non-combustible components such as metal, ceramics, and gravel, and the combustible components are pulverized and powdered. The pulverized combustible component and the above-mentioned pyrolysis gas are introduced into a waste combustion melting furnace and burned, and the resulting combustion ash is heated by the combustion heat to form molten slag. Flowing down the furnace inner surface covered with refractory material Is discharged from the discharge portion to the outside and so as to cool and solidify waste disposal apparatus has been known (e.g., see Patent Document 1.).

  On the other hand, refractory materials are used in industrial kilns, boilers, waste incinerators and the like that require high-temperature treatment such as steel, non-ferrous metals, cement, glass, and ceramics. When using this refractory material, when using it in an environment where it comes into contact with molten slag, it is necessary to consider not only the gas phase environment such as oxygen partial pressure and alkali partial pressure, but also severe high-temperature corrosion involving molten slag. There is a need to.

In general, oxide-based refractories are used under conditions where oxygen partial pressure is high, but in the case of oxide-based refractories in waste treatment that burns and melts with air, aluminum oxide (Al ₂ O ₃ : Neutral refractory mainly composed of alumina is selected (for example, see Patent Document 2).

However, the molten slag obtained by melting the ash content of the waste treatment apparatus has a low basicity and a high solubility of refractory components such as alumina and magnesia because of the coexistence of oxidizing gases such as chlorine and sulfur. . In addition, even if these molten components dissolve in the slag and the concentration in the slag increases, the viscosity of the slag does not increase particularly, so the dissolution of these refractory components into the slag continues. There is a problem of progressing to.
Japanese Patent Publication No. 06-56253 JP 2004-217517 A

  The present invention has been made in order to solve the above-described problems. The purpose of the present invention is to provide a refractory material that constitutes the inner wall of a waste combustion melting furnace that burns and melts waste and the like to form slag. An object of the present invention is to provide a refractory material and a waste combustion melting furnace capable of suppressing the progress of melting of the refractory material by preparing the slag to have a high viscosity when it is melted in the molten slag.

  In order to achieve the above object, the refractory material of the present invention includes 95 mass% to 99 mass% (95 wt% to 99 wt%) of a refractory main material composed of aluminum oxide or zinc spinel, and 5 mass. % To 1 mass% (5 wt% to 1 wt%) of a refractory material, and 0.5 mass% to 25 mass% (0.5 wt% to 25 wt%) added as an outer shell The material includes potassium aluminate.

This zinc spinel contains ZnAl ₂ O ₄ crystal, contains 39 mass% to 49 mass% (39 wt% or more and 49 wt% or less) of ZnO component, and the total of ZnO component and Al ₂ O ₃ component is 95 mass% or more. There is something.

  That is, in a refractory material constituting a furnace inner wall such as a furnace that burns and melts waste to form slag, the refractory main material is 95 mass% to 99 mass%, and the binder is 5 mass% to 1 mass%.

  In the refractory material thus prepared, the potassium ion-oxygen attractive force is small, and the basicity of the system is increased upon dissolution in the molten slag. Therefore, the proportion of alumina acting as a network-forming oxide is high. Thus, aluminum ions and oxygen ions form inorganic polymer chains. Therefore, the viscosity of the molten slag increases and the mass transfer rate decreases. Therefore, the corrosion resistance of the refractory material is improved.

  And, potassium aluminate is used as an additive. Here, when the content of potassium aluminate is less than 0.5 mass% on the basis of the total amount of the refractory main material and the binder, the viscosity of the molten slag Improvement effect does not appear. On the other hand, if the content is more than 25 mass%, the instability due to absorption of carbon dioxide or moisture appears and the practicality is lost.

  When the waste combustion melting furnace is formed using the above-mentioned refractory material as a furnace wall material for the furnace wall in contact with the melt, the corrosion resistance against the molten slag can be improved.

  According to the refractory material and the waste combustion melting furnace of the present invention, in a waste combustion furnace that burns and melts waste to form slag, the corrosion resistance of the refractory material constituting the furnace inner wall to the molten slag can be improved. In addition, by adding potassium aluminate to the refractory main material, the potassium ion-oxygen attractive force in the molten slag is small, and the basicity of the system can be increased when the potassium aluminate is dissolved in the molten slag. The proportion of alumina acting as a network-forming oxide is increased, the viscosity of the molten slag can be increased, and the corrosion resistance of the refractory material can be increased.

Hereinafter, embodiments of the refractory material and the waste combustion melting furnace according to the present invention will be described.
First, an embodiment of the refractory material according to the present invention will be described. This refractory material is a refractory material containing 95 mass% to 99 mass% of a refractory main material composed of aluminum oxide or zinc spinel, and 5 mass% to 1 mass% of a binder. As an additive of 0.5 mass% to 25 mass%, potassium aluminate (KAlO ₂ ) containing elemental potassium having a large ionic radius is included.

  And this aluminum oxide adjusts an electromelted product, a sintered product, etc. to a coarse grain, a medium grain, a fine grain, etc. as needed, but calcined alumina may be used. This aluminum oxide is the main component of the refractory material, and α-alumina (corundum) is used as the crystal phase, so that the mechanical strength is high and the thermal conductivity is relatively high.

On the other hand, the zinc spinel contains ZnAl ₂ O ₄ crystals, contains 39 mass% or more and 49 mass% or less of the ZnO component, and has a total of 95 mass% or more of the ZnO component and the Al ₂ O ₃ component. It can be produced by a solid phase reaction with aluminum oxide powder. This zinc spinel, like aluminum oxide, is the main component of the refractory material. This material is characterized by a cubic crystal structure and high heat-resistant spalling properties.

  In addition to the above-mentioned aluminum oxide or refractory main material composed of zinc spinel, a refractory material such as aluminum lactate, alumina cement, phosphate, and the like are added and mixed to increase the strength, The fireproof main material is 95 mass% to 99 mass%, and the binder is the remaining%, that is, 5 mass% to 1 mass%.

In the present invention, potassium aluminate (KAlO ₂ ) containing elemental potassium having a large ionic radius is used as the additive. The amount of this additive is 0.5 mass% or more and 25 mass% or less as an outer shell.

  Here, if the content of potassium aluminate is less than 0.5 mass%, the effect of improving the viscosity of the molten slag is not expressed, and if it is more than 25 mass%, anxiety due to absorption of carbon dioxide or moisture Qualitative appears and practicality disappears.

  In addition, in order to reduce the influence of the workability of the irregular refractory and the ambient temperature at the time of construction, a dispersant and a curing regulator may be added as necessary. These can be added by mixing in advance in a mixture of a refractory main material and a binder, or by dissolving or suspending in a water added during kneading.

  And this dispersing agent is preferably about 0.02 mass% to 0.2 mass% as an outer shell with respect to the total amount of the refractory main material and the binder, and the curing modifier is also a refractory main material. It is preferable that the outer shell is approximately 0.05 mass% to 0.2 mass% with respect to the total amount of the binder.

  The above fireproof main material, binder, additive and the like are mixed in a predetermined ratio, and then put into a mold and molded into a predetermined shape. This molded body is cured and dried. Thereafter, the compact is put into a heating furnace (firing furnace), heated and sintered at 1400 ° C. to 1700 ° C., and the sintered product is cooled to obtain a shaped refractory.

  Moreover, when using as an irregular refractory material, the powder which mixed said fireproof main material, binder, additive, etc. in a predetermined ratio is used. When forming the inner wall of the furnace using this amorphous refractory, the powder of the amorphous refractory added with water and kneaded is poured into a mold provided on the furnace wall to form the inner wall of the furnace. Curing and drying. Then, this furnace inner wall is heated at 1200-1400 degreeC with a combustion burner etc., and a furnace inner wall is baked.

Then, the refractory material produced by the above manufacturing method, since in addition 0.5mass% ~25mass% potassium aluminate containing large becomes elemental potassium ion radius refractory main member of (Kalo ₂₎ in outer percentage Since the attractive force between potassium ions and oxygen in the molten slag is small, the basicity of the system increases during dissolution of potassium aluminate in the molten slag, and the proportion of alumina acting as a network-forming oxide increases. Increased viscosity. This increases the corrosion resistance of the refractory material.

  Next, a waste combustion melting furnace using this refractory material will be described. The waste combustion melting furnace shown in FIG. 1 is a melting furnace used in the following waste combustion melting system.

  In this waste combustion melting system, waste including municipal solid waste and other combustible materials such as waste plastic is placed in a thermal decomposition reactor and heated in a low oxygen atmosphere for thermal decomposition. By this pyrolysis, pyrolysis gas (dry distillation gas) and pyrolysis residue mainly composed of nonvolatile components are generated. This pyrolysis gas and pyrolysis residue are separated in a discharge device.

  After this pyrolysis residue is cooled by a cooling device under an inert atmosphere, it is supplied to a separation device to produce a combustible component mainly composed of pyrolytic carbon and a non-combustible component such as metal, ceramics, and gravel. To separate. The combustible component is pulverized to form a powder, and the pulverized combustible component and the pyrolysis gas are guided to a waste combustion melting furnace and burned. The combustion ash generated by this combustion is heated by the combustion heat to form molten slag. The molten slag flows down the furnace inner surface covered with a refractory material, and is discharged from the discharge portion to the outside to be cooled and solidified.

  In the waste combustion melting furnace 1 shown in FIG. 1, the combusted combustible component F is introduced into the waste combustion melting furnace 1 from the inlet 21 and the pyrolysis gas G is introduced from the gas inlet 22. In addition, combustion air A is introduced from the air supply port 23. Then, the combustible component F and the pyrolysis gas G are mixed with the air A and combusted, and the combustion ash generated by this combustion is heated by the combustion heat to form molten slag C. The molten slag C flows down along the furnace inner surface covered with the refractory material, and is discharged from the discharge portion 24 to the outside and solidifies by cooling.

  In the waste combustion melting furnace as shown in FIG. 1, the furnace inner wall portion (cross hatched portion) with which the molten slag comes into contact is formed using the above refractory material. In this case, the furnace inner wall may be formed by stacking shaped refractories obtained by sintering refractory materials into a predetermined shape, and this refractory material may be used as a powdered castable refractory or kneaded clay refractory. It may be used as an indeterminate refractory, etc., and after the furnace inner wall is formed by casting or the like, the furnace inner wall may be fired by heating.

  By forming the portion of the inner wall of the furnace in contact with the molten slag of the waste combustion melting furnace 1 with the refractory material having the above-described configuration, the corrosion resistance against the molten slag of the inner wall of the waste combustion melting furnace 1 can be improved.

  Next, the corrosion test performed for evaluating the performance of the refractory material having the above-described configuration will be described. The base material is zinc spinel and zinc spinel + alumina, potassium aluminate is used as an additive, and aluminum lactate is used as a binder, and the mixture shown in Table 1 is mixed, molded, and sintered. 1-4 round bar-shaped samples (φ10 mm × 75 mm) were prepared.

  This was immersed in an actual machine-collected slag having the composition shown in Table 3 and subjected to a corrosion test. After dipping at a predetermined temperature and time, the round bar-shaped sample was cut, and the amount of corrosion was determined from the change in the outer diameter before and after the experiment. As a result, a thinning amount as shown in Table 1 was obtained.

  On the other hand, in the same manner as shown in Table 2, single oxide alumina was used to produce a round bar sample of a comparative example (φ10 mm × 75 mm) together with a binder, and immersed and corroded in the same actual machine collected slag having the composition shown in Table 3. Went. As a result, a thinning amount as shown in Table 2 was obtained.

  From the comparison of Tables 1 and 2, corrosion resistance superior to that of single oxide alumina was recognized in the sample in which potassium aluminate was added to the composite oxide / zinc spinel.

It is a figure which shows the waste combustion melting furnace of embodiment which concerns on this invention.

Explanation of symbols

1 Waste Combustion Melting Furnace 21 Input Port 22 Gas Input Port 23 Air Supply Port 24 Discharge Port A Combustion Air C Molten Slag F Combustible Component G Pyrolysis Gas

Claims (2)

  95 mass% to 99 mass% of a refractory main material composed of aluminum oxide or zinc spinel, and 5 mass% to 1 mass% of a binder, and 0.5 mass% to 25 mass on the outside % Refractory material containing potassium aluminate as additive. A waste combustion melting furnace using the refractory material according to claim 1 as a furnace wall material for a furnace wall in contact with a melt.

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