JP2007131498A - Matrix material for refractory material, refractory material, and waste incinerating/melting furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a matrix material for refractory improved in corrosion resistance of a refractory composing a furnace inner wall to the melted slag generated by incinerating and melting waste, and to provide the refractory and a waste incinerating/melting furnace. <P>SOLUTION: The matrix material for refractory comprises an oxide material composed of a (non)stoichiometric spinel single phase (magnesia-spinel single phase), and contains tetravalent oxides of ≥0.1 mass% and <1 mass% as a solid solution component. The magnesia-spinel single phase includes a spinel crystal only as the crystal phase identified by an X-ray analysis, and the MgO ingredient content in magnesia-alumina binary expression is within the range of ≥7 mass% and ≤39 mass%. <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. A refractory material matrix material used as a refractory material constituting the inner surface of a waste combustion melting furnace that heats the generated ash to form molten slag, a refractory material containing the refractory material matrix material, and this refractory material The present invention relates to a waste combustion melting furnace to be used.

  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, consider the severe high-temperature corrosion involving molten slag as well as the environment on the gas phase side such as oxygen partial pressure and alkali partial pressure. There is a need to.

In general, oxide-based refractory materials are used under conditions of high oxygen partial pressure, but in the case of oxide-based refractory materials for waste treatment that burns and melts with air, magnesia-alumina composite system is used. A mixed refractory material of magnesia spinel (MgAl ₂ O ₄ ) -magnesia has been proposed (see, for example, 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 order to increase the corrosion resistance of the refractory material to these molten slag and oxidizing gas, a matrix material having high physical and chemical durability is required. That is, the single oxide component of alumina or magnesium is different from the oxide (magnesia spinel) in which the thermal expansion characteristics are combined, and has problems such as low volume stability and easy cracking, and silica component in ash. There is a problem that it easily reacts with alkali components and SOx content in exhaust gas. Therefore, damage and wear such as partial peeling of the refractory material and intrusion of molten slag are likely to occur, resulting in a problem that wear of the refractory material such as spalling and melting continuously proceeds.
Japanese Examined Patent Publication No. 6-56253 JP 2001-158661 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 the furnace in contact with the molten slag in a waste combustion melting furnace that burns and melts waste to form slag. It is an object of the present invention to provide a suitable refractory matrix material, a refractory material including the refractory matrix material, and a waste combustion melting furnace using the refractory material.

  The matrix material for a refractory material of the present invention for achieving the above object is composed of a magnesia spinel single phase containing a spinel crystal as a crystal phase and having an MgO component content in the range of 7 mass% to 39 mass%. A matrix material for a refractory material, which is configured to contain a tetravalent metal oxide as a solid solution component in an amount of 0.1 mass% to less than 1 mass%.

  The matrix material for a refractory material includes one or more of titanium oxide, zirconium oxide, tin oxide, and hafnium oxide as the tetravalent metal oxide.

  In the matrix material for refractory material prepared as described above, it is a highly symmetrical phase called cubic, and it is a single phase, so the temporal and spatial temperature fields such as temperature rise and fall, local combustion, etc. There is no variation in thermal expansion characteristics during fluctuations, and stability is high.

  In addition, since the tetravalent metal oxide is contained as a solid solution component, the cation vacancy concentration in the crystal is high, the diffusion coefficient is increased, and the sintering behavior when the powder is raised from a normal temperature state to a high temperature state, The final density of the sintered body increases.

  Therefore, damage factors such as mechanical damage and physical penetration of molten slag are reduced. Here, the addition rate of the tetravalent metal oxide is 0.1 mass% or more and less than 1 mass%, and is within the formation range of the solid solution.

  Moreover, since the matrix material for refractory materials prepared as mentioned above is a complex oxide with high stability at the time of chemical erosion of molten slag, mass transfer into the molten slag is suppressed. Therefore, the corrosion resistance of the refractory material is improved.

And the refractory material of this invention for achieving said objective is comprised including said matrix material for refractory materials. The refractory material having this configuration is a refractory material in which mass transfer into the molten slag is suppressed, that is, a refractory material excellent in corrosion resistance.Furthermore, the waste combustion melting furnace of the present invention for achieving the above object is When the refractory material including the matrix material for the refractory material is used 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 matrix material for a refractory material and the refractory material of the present invention, in a waste combustion melting furnace for combusting and melting waste to form slag, it consists of a spinel single phase containing tetravalent metal oxide in a concentration within the solid solution limit. By applying a sample to the matrix part of a refractory material, the corrosion resistance with respect to the molten slag of the refractory material containing this matrix material for refractory materials can be improved.

  Further, according to the waste combustion melting furnace of the present invention, the refractory material including the matrix material for the refractory material is used to constitute the inner wall of the waste combustion melting furnace, so the molten slag of the waste combustion melting furnace Corrosion resistance to can be improved.

  Hereinafter, embodiments of the matrix material for refractory material, the refractory material, and the waste combustion melting furnace according to the present invention will be described.

  First, an embodiment of a matrix material for a refractory material according to the present invention will be described. This matrix material for a refractory material is a matrix material for a refractory material that includes a spinel-type crystal as a crystal phase and is composed of a magnesia spinel single phase having a MgO component content in the range of 7 mass% to 39 mass%. It is comprised so that a valence metal oxide may be contained as a solid solution component in an amount of 0.1 mass% (wt%) or more and less than 1 mass%.

  That is, an oxide material composed of a stoichiometric or non-stoichiometric spinel single phase and containing a tetravalent oxide as a solid solution component is applied to a matrix material for a refractory material. As the tetravalent metal oxide, any one or two or more of titanium oxide, zirconium oxide, tin oxide, and hafnium oxide can be used. The addition rate of this tetravalent metal oxide is 0.1 mass% or more and less than 1 mass%, and is within the formation range of the solid solution.

  Here, the magnesia spinel single phase includes only spinel crystals as crystal phases identified by X-ray analysis, and the content of MgO component in the magnesia-alumina binary display is in the range of 7 mass% to 39 mass%. Say.

  Since this matrix material for refractory materials is a highly symmetrical phase called cubic, and it is a single phase, there is a variation in thermal expansion characteristics when temporal and spatial temperature fields fluctuate, such as temperature rise and fall and local combustion. There is no stability.

  Moreover, since tetravalent metal oxide is contained as a solid solution component, the cation vacancy concentration in the crystal is high, the diffusion coefficient is increased, and the sintering behavior when the powder is raised from the normal temperature state to the high temperature state is reduced. The final density of the body is increased. Therefore, damage factors such as mechanical damage and physical penetration of molten slag are reduced.

  Moreover, since the matrix material for refractory materials prepared in this way is a complex oxide with high stability at the time of chemical erosion of molten slag, mass transfer into the molten slag is suppressed. Therefore, the corrosion resistance of the refractory material including the matrix material for refractory material is improved.

  The matrix material for the refractory material is a component constituting the fine part (particle size is 0.1 mm or less) to the fine part of medium grain (0.1 mm to 1 mm), whereas the coarse part and coarse grain ( The particle component constituting 1 mm or more) is called aggregate. For the aggregate, fused alumina, fused spinel, fused zirconia or the like is used. The refractory material has a refractory main material composed of the matrix material and the aggregate as a basic component. A refractory material is formed by blending a binder for imparting bonding and strength, a dispersant, a curing retarder, and the like.

  The above-mentioned matrix material for refractory material, binder, additive and the like are mixed at 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 fixed refractory material.

  Moreover, when using as an amorphous refractory material, the powder which mixed said refractory material matrix material, a binder, an additive, etc. in a predetermined ratio is used. When forming the furnace inner wall using this irregular refractory material, the powder of the irregular refractory material added with water and kneaded is poured into a mold provided on the furnace wall to form the furnace inner wall. 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.

  And since the refractory material manufactured by the above manufacturing method contains a matrix material for refractory material, which is a complex oxide that is highly stable during chemical erosion of molten slag, the material from the refractory material into the molten slag Movement is suppressed. Therefore, the corrosion resistance of the refractory material is improved.

  Next, a waste combustion melting furnace using a refractory material including the matrix material for the 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 1 as shown in FIG. 1, a 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 refractory materials obtained by sintering the refractory materials into a predetermined shape, and this refractory material may be used as a powdered castable refractory material or a kneaded clay refractory material. The inner wall of the furnace may be formed by casting or the like, and then heated to fire the inner wall of the furnace.

  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.

  As test specimen compositions, those shown in Examples 1 to 6 in Table 1 were prepared, pressure-molded, heated to 1600 ° C. in order to cause a solid-phase reaction in the atmosphere, and a stoichiometric spinel or non-stoichiometric spinel was used. Produced. The compounding ratio of magnesia to alumina is a magnesia-alumina phase diagram, and the composition region is selected so that a single phase with a specific ratio or non-stoichiometric spinel is generated. This was pulverized into a fine powder. A part of this was inspected by the powder X-ray method, and it was confirmed that it was a spinel single phase.

  The pulverized powder was classified to a particle size of 0.5 mm or less, and after molding, sintered in the atmosphere at 1400 ° C. to 1600 ° C. The phase state after sintering was also confirmed.

  This was cut out to produce a relative density measurement sample (φ10 mm × 5 mm) and a round bar sample (φ10 mm × 75 mm) for corrosion resistance evaluation. This relative density was measured by the Archimedes method. Further, in the corrosion resistance evaluation, a test was performed in which corrosion was performed by immersing in actual machine-collected slag having the composition shown in Table 3.

  In this corrosion test, after immersing at 1400 ° C. for 20 hours, a round bar sample was cut, and the amount of corrosion wear was determined from the change in the outer diameter before and after the experiment. As a result, corrosion wear as shown in Table 1 was obtained.

On the other hand, as comparative examples, the following three types were produced by composition control. (1) Stoichiometric spinel single phase not containing tetravalent metal oxide, (2) Nonstoichiometric spinel single phase not containing tetravalent metal oxide, (3) Spinel and tetravalent metal oxide Two-phase coexistence system.
(1) was prepared by adjusting the raw materials so as to be a stoichiometric spinel.
(2) was selected and synthesized so that the alumina content in the magnesia-alumina binary display would be 75 mass% to 80 mass% so as to be in the non-stoichiometric spinel single phase region.
(3) was synthesized by adjusting the tetravalent metal oxide to an excessively high ratio to a specific ratio spinel produced separately.

  These were previously identified by X-ray analysis. Then, it shape | molded on the same conditions as an Example, and sintered. The sintered sample was cut out to produce a relative density measurement sample (φ10 mm × 5 mm) and a round bar sample (φ10 mm × 75 mm) for corrosion resistance evaluation. Moreover, a part was cut out from the sintered sample, and the phase state was also confirmed. This round bar-like sample was subjected to a corrosion test immersed in an actual machine-collected slag in the same manner as described above. The results are shown in Table 2.

  From the comparison of Table 1 and Table 2, the corrosion resistance was compared. As a result, in the sample containing the tetravalent metal oxide at a concentration within the solid solution limit, the corrosion resistance superior to the sample not containing the tetravalent metal oxide and the sample containing excessive tetravalent metal oxide was recognized. .

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 (4)

  A matrix material for a refractory material composed of a magnesia spinel single phase containing a spinel type crystal as a crystal phase and having an MgO component content in a range of 7 mass% to 39 mass%, and a tetravalent metal oxide as a solid solution component As a matrix material for a refractory material, containing 0.1 mass% or more and less than 1 mass%.   2. The matrix material for a refractory material according to claim 1, wherein the tetravalent metal oxide includes one or more of titanium oxide, zirconium oxide, tin oxide, and hafnium oxide.   A refractory material comprising the matrix material for a refractory material according to claim 1 or 2. A waste combustion melting furnace using the refractory material according to claim 3 as a furnace wall material of a furnace wall in contact with the melt.

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