JP4575761B2 - Refractory material for inner wall of furnace and waste combustion melting furnace - Google Patents

Description

  The present invention relates to a refractory material for an inner wall of a furnace, and industrial waste such as waste (general waste such as municipal waste from homes and offices, waste plastic, car shredder / dust, electronic equipment, cosmetics, etc.) Combustion waste that includes flammable slag by heating the ash generated by incineration of materials, including combustible materials, etc., and using the refractory material for the inner wall of the furnace as the furnace wall material Related to melting furnace.

    Conventionally, waste is processed using, for example, a waste processing apparatus. In this waste treatment apparatus, for example, waste is transported to a pyrolysis reactor and pyrolyzed to become dry distillation gas and non-volatile pyrolysis residue, and the pyrolysis residue is introduced into the combustion melting furnace. It is melted and taken out as slag.

  For example, as one of the waste treatment equipment containing combustibles such as municipal waste and combustible waste such as municipal waste, the waste is put in a pyrolysis reactor and heated in a low-oxygen atmosphere for thermal decomposition, A pyrolysis gas (dry distillation gas) and a pyrolysis residue mainly composed of non-volatile components are generated, and the pyrolysis gas and the 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 the separation device and separated into combustible components mainly composed of pyrolytic carbon and non-combustible components such as metal, ceramics, gravel, etc. The pulverized combustible component and the above-mentioned pyrolysis gas are led to a combustion melting furnace and burned, and the resulting combustion ash is heated by the combustion heat to form molten slag. Flows down the furnace inner surface covered with refractory material And so as to cool and solidify and discharged to the outside through the discharge unit waste disposal apparatus has been known (KOKOKU 6-56253 Patent Publication).

  Refractory materials for furnace inner walls are used in industrial kilns, boilers, waste incinerators, etc. that require high-temperature treatment such as steel, non-ferrous metals, cement, glass, and ceramics. In use in an environment in contact with molten slag, it is necessary to consider severe high temperature corrosion involving molten slag as well as the gas phase environment such as oxygen partial pressure and alkali partial pressure.

In general, an oxide refractory is used when the oxygen partial pressure is high. In the case of oxide-based refractories in waste treatment that burns and melts in air, neutral refractories mainly composed of aluminum oxide Al ₂ O ₃ (alumina), or compound magnesia of alumina and magnesium oxide MgO (magnesia) Spinel MgAl ₂ O ₄ may be selected (Japanese Patent Laid-Open Nos. 2004-217517 and 2002-128573).

However, molten slag is low in basicity and coexists with oxidative gases such as chlorine and sulfur. In addition to the high solubility of refractory materials such as alumina and magnesia, the concentration of these dissolved components in the slag is increased. At this time, the viscosity does not increase particularly. Therefore, dissolution of these refractory materials into the slag continues and the refractory material is reduced in thickness, so that the corrosion resistance of the refractory material is deteriorated.
Japanese Examined Patent Publication No. 6-56253 JP 2004-217517 A JP 2002-128573 A

  An object of the present invention is for a furnace inner wall that is difficult to dissolve in molten slag and has improved corrosion resistance against molten slag even when the furnace inner wall is configured as a furnace wall for burning and melting waste to form slag. An object is to provide a refractory material and a waste combustion melting furnace using the refractory material as a furnace wall material.

The present invention is a refractory material comprising 95 to 99.5 % by weight of a refractory main material composed of aluminum oxide or magnesia spinel and 0.5 to 5 % by weight of a binder, comprising alkali aluminate (RAlO ₂ ; R = potassium, rubidium, cesium) in outer percentage with containing 5 to 25 wt%, the binder is summarized as alumina cement or aluminum lactate der Ru furnace inner wall refractory material. Here, the magnesia spinel includes MgAl ₂ O ₄ crystals, 5.7 to 38.5% by weight of MgO component, and 95% by weight or more of the total of MgO component and Al ₂ O ₃ component. .

  Further, the present invention is a melting furnace that heats the ash generated by incineration of waste to form molten slag, and a waste combustion melting furnace using the above-mentioned refractory material for the furnace inner wall as a furnace wall material. To do.

In the present invention, alkali aluminate (RAlO ₂ ; R = potassium, rubidium, cesium) is used, and this alkali aluminate contains an alkali element R having a large ionic radius, such as potassium, rubidium, and cesium. , The R cation-oxygen attractive force is small and the basicity of the system is increased when the refractory material is dissolved in the molten slag, so that the proportion of alumina acting as a network-forming oxide increases, and aluminum ions and oxygen ions Inorganic polymer chains are formed. For this reason, the viscosity of the molten slag increases, and the mass transfer rate from the refractory material to the molten slag decreases. Therefore, the corrosion resistance of the refractory material is improved.

As described above, according to the present invention, since the alkali aluminate (RAlO ₂ ; R = potassium, rubidium, cesium) is used, the inner wall of the furnace is used as the wall of the furnace for burning and melting waste to form slag. Providing a refractory material for the inner wall of a furnace that has improved slag viscosity and improved corrosion resistance against molten slag, and a waste combustion melting furnace using the refractory material as a furnace wall material It becomes possible to do.

The refractory material for an inner wall of the furnace of the present invention is a refractory material containing 95 to 99.5 % by weight of a refractory main material composed of aluminum oxide or magnesia spinel and 0.5 to 5 % by weight of a binder. Alkaline (RAlO ₂ ; R = potassium, rubidium, cesium) is contained in an outer coating of 5 to 25% by weight. Here, the magnesia spinel includes MgAl ₂ O ₄ crystals, 5.7 to 38.5% by weight of MgO component, and 95% by weight or more of the total of MgO component and Al ₂ O ₃ component. .

Magnesia spinel is composed of magnesia and alumina MgO: 23-60%,
Al ₂ O ₃ : Prepared by a method of firing a raw material mixture mixed so as to be in the range of 40 to 77%, or a method of melting the raw material mixture by an electric melting method, cooling, pulverizing, and sizing Is done.

As the binder, use the Alumina cement or aluminum lactate.

  Here, when content of alkali aluminate is less than 5 weight%, the effect of the viscosity improvement of molten slag is not expressed. On the other hand, if the content is more than 25% by weight, instability due to absorption of carbon dioxide or moisture appears, and practicality is lost.

  When the refractory material for a furnace inner wall according to the present invention thus formed is used as a furnace wall material for a furnace such as a waste combustion melting furnace, the inner wall surface is formed by using an amorphous or sintered product of the refractory material. May be configured.

  You may add a dispersing agent or a hardening regulator as needed.

  The curing modifier includes a curing accelerator and a curing retardant, and potassium carbonate and the like can be preferably used as the curing accelerator, and oxalic acid and boric acid and the like can be preferably used as the curing retardant.

Example 1
The base material is alumina and / or magnesia spinel, potassium aluminate is used as an additive, and aluminum lactate is used as a binder, and mixed, molded, and sintered in a composition such as Composition 1 to Composition 4 shown in Table 1, A round bar sample was prepared. This was immersed in an actual machine-collected slag having the composition shown in Table 3 and subjected to a corrosion test. After immersion at a predetermined temperature and time, the sample was cut, and the amount of corrosion was determined from the change in outer diameter before and after the experiment. As a result, the corrosion index as shown in Table 1 was obtained. Here, the corrosion index is represented by a relative value of the thinning amount of each sample, assuming that the thinning amount in the same corrosion condition in alumina sintered at the same temperature is 100. The smaller this index, the higher the corrosion resistance.

(Example 2)
The same test as in Example 1 was performed except that rubidium aluminate was used as the alkali aluminate. As a result, corrosion resistance as described in the column of composition 5 in Table 1 was obtained. This corrosion resistance is superior to the cases of alumina alone and magnesia spinel alone shown in Table 2, and is interpreted to be caused by the fact that this aluminate material has increased melt slag viscosity.

(Example 3)
The same test as in Example 1 was performed except that cesium aluminate was used as the alkali aluminate. As a result, corrosion resistance as described in the column of composition 6 in Table 1 was obtained. This corrosion resistance is superior to the cases of alumina alone and magnesia spinel alone shown in Table 2, and is interpreted to be caused by the fact that this aluminate material has increased melt slag viscosity.

(Comparative Example 1)
The same test as in Example 1 was performed except that the base material was alumina or magnesia spinel and no alkali aluminate was added. The results are shown in Table 2.

  From the comparison between Table 1 and Table 2, excellent corrosion resistance was observed in the samples to which alkali aluminate was added.

Claims (2)

A refractory material comprising 95 to 99.5 % by weight of a refractory main material composed of aluminum oxide or magnesia spinel and 0.5 to 5 % by weight of a binder, comprising alkali aluminate (RAlO ₂ ; R = potassium, rubidium, Cesium) is contained 5 to 25% by weight , and the magnesia spinel includes MgAl ₂ O ₄ crystals, 5.7 to 38.5% by weight of MgO component, and MgO component and Al ₂ O _A refractory material for a furnace inner wall , wherein the total of the _three components is 95% by weight or more, and the binder is alumina cement or aluminum lactate . A waste combustion melting furnace using a refractory material for a furnace inner wall according to claim 1 as a furnace wall material, wherein the ash content generated by incineration of waste is heated to form molten slag.