JP4205926B2 - Unshaped refractory for waste melting furnace and waste melting furnace lined with it - Google Patents

Description

【表２】

【表３】

カルボキシル基含有ポリエーテル系分散剤は、花王株式会社製のタイトロック（登録商標）Ｐ−１００を使用した。
【００４１】
各例は、表に示す不定形耐火物の配合組成物をミキサーにて混練した後、金属製の型枠に流し込んだ。流し込みの際には型枠に振動を付与し、施工体の充填を促進した。ついで、２４時間養生し、脱型後、１１０℃×２４時間乾燥して４０×４０×長さ１６０ｍｍの試験片を得た。試験方法以下のとおりである。
【００４２】
かさ比重：ＪＩＳ Ｒ２２０５に準じて測定した。
【００４３】
強度：試験片を更に１４００℃×３時間焼成後、ＪＩＳ Ｒ２５５３に準じた曲げ強さをもって測定した。
【００４４】
耐食性：ガス化溶融炉から排出したスラグ（質量比でＣａＯ／ＳｉＯ_２：０.７４）を侵食剤とし、１６５０℃×２０時間での回転侵食試験を行なった。侵食寸法を測定し、比較例１の侵食寸法を１００とした指数で示した。数値が小さいほど耐食性に優れていることを示す。
【００４５】
実機試験：一日あたりのごみ処理量が１００ｔのガス化溶融炉に内張りし、１２ヶ月間の使用後において、損耗速度（ｍｍ／月）を測定した。このガス化溶融炉の操業温度は１４００℃、そのスラグ成分は質量％で、ＳｉＯ_２：４２.８、ＣａＯ：３１.７、Ａｌ_２Ｏ_３：１２.４、Ｆｅ_２Ｏ_３：４.８、Ｎａ_２Ｏ：３.７、（ＣａＯ／ＳｉＯ_２：０.７４）であった。
【００４６】
試験結果が示すとおり、本発明の実施例はいずれも施工時の添加水量が少なく、しかも、かさ比重の測定値のとおり緻密な施工体を形成することができた。その結果、廃棄物溶融炉における耐火物使用時を想定した１４００℃での焼成後の強度および耐食性において、いずれも優れた効果を発揮している。
【００４７】
これに対し、比較例１および比較例２は分散剤が本発明とは異なり、しかもＣａ化合物を添加しておらず、施工時の流動性確保のために添加水量が多いことで施工体の緻密性に劣り、その結果、強度および耐食性が劣る。
【００４８】
比較例３はカルボキシル基含有ポリエーテル系分散剤を使用しているが、Ｃａ化合物の添加がないために施工時の流動性に劣り、流動性確保のため添加水量を多くしたことで強度および耐食性に劣る。
【００４９】
比較例４は、酸化クロム超微粉の使用量が少なく、添加水分量が少なくても緻密な施工体が形成できるが、クロミヤ不足で耐食性に劣る。比較例５は、酸化クロム超微粉の使用量が多すぎ、分散性に劣り、添加水量を多く必要とするために、強度および耐食性に劣る。
【００５０】
比較例６は消石灰を添加しているが、分散剤がポリアクリル酸ソーダであり、流動性に劣るために添加水分量が多くなり、緻密な施工体が得られず、強度および耐食性に劣る。比較例７はＣａ化合物としての消石灰の添加量が多すぎ、耐食性に劣る。
【００５１】
また、本発明の廃棄物溶融炉用不定形耐火物として、その優れた耐食性の効果はガス化溶融炉における実機試験結果において確認される。
【００５２】
【発明の効果】
廃棄物成分からのアルカリ、酸に起因した廃棄物溶融炉特有のスラグ成分に対し、本発明の耐火物は以上の実施例の試験結果が示とおり、優れた耐用性を発揮する。近年、都市ゴミ焼却炉、ガス化溶融炉等の廃棄物溶融炉はその高温操業によって耐火物の使用条件が過酷化しており、本発明はこれに対応できる耐火物として、その産業的価値はきわめて高い。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an irregular refractory for casting construction used as a lining in a waste melting furnace such as a gasification melting furnace or an ash melting furnace for volume reduction of waste, and a waste lining the amorphous refractory. Related to melting furnace.
[0002]
[Prior art]
The operating conditions of waste melting furnaces are becoming increasingly severe in order to suppress dioxin generation and further reduce the volume of waste. For example, the operation temperature of municipal waste incinerators has been increased from 800 to 1000 ° C. to 1000 to 1200 ° C., which is a higher temperature, for the purpose of suppressing dioxin generation. In recent years, the use of gasification melting furnaces that melt and reduce waste at ultrahigh temperatures such as 1400 to 1500 ° C. or 1600 ° C. or more has been expanded.
[0003]
For example, the components of slag generated in blast furnaces, molten metal containers and the like in the iron manufacturing industry are CaO / SiO ₂ : 1 to 4 by mass ratio, and the alkali content is 0.1 mass% or less. In the molten contents, the slag is a part that floats on the molten metal.
[0004]
On the other hand, the component of the slag of the waste melting furnace contains an alkali such as sodium and an acid such as chlorine derived from the waste component, and CaO / SiO ₂ : 0.3 to 1.5 by mass ratio, containing an alkali. The amount is 1 to 10% by mass. Moreover, most of the molten content is slag.
[0005]
The operation of the waste melting furnace is largely different from blast furnaces, molten metal containers, and the like because the slag component having a high alkali content and the molten content are substantially only slag. In particular, in the case of a gasification melting furnace operated at a temperature of 1400 ° C. or higher, the slag wear action is even more severe.
[0006]
Lined refractories for waste melting furnaces are roughly classified into regular refractories and irregular refractories. The construction of the regular refractory is a brickwork, requiring heavy labor and high technology. In recent years, therefore, lining with an irregular refractory has been widely used.
[0007]
Alumina-chromia or alumina-chromia-zirconia amorphous refractories have been proposed as the amorphous refractories for the waste melting furnace lining (for example, Patent Document 1 and Patent Document 2).
[0008]
In this irregular refractory material, alumina has corrosion resistance and volume stability, and chromia has slag penetration resistance. The chromia component is indispensable for the slag with high alkali content specific to waste melting furnaces from the viewpoint of preventing slag penetration.
[0009]
[Patent Document 1]
JP-A-8-48574 (page 1-3)
[0010]
[Patent Document 2]
JP 10-324562 A (page 1-5)
[0011]
[Patent Document 3]
JP 2000-335978 A (page 1-4)
[0012]
[Problems to be solved by the invention]
The irregular refractory for the waste melting furnace is added with a dispersing agent for imparting fluidity during construction in the same manner as other irregular refractories. On the other hand, chromium oxide ultrafine powder is mainly used as the chromia component, and an alumina-chromia solid solution is formed by reaction with the alumina component of the main aggregate. This alumina-chromia solid solution exhibits an effect of preventing slag penetration against slag generated in a waste melting furnace.
[0013]
However, the use of this ultrafine chromium oxide powder, in addition to the ultrafine particles of chromium oxide, increases the viscosity during construction of the amorphous refractory due to its surface properties, and a dense construction body cannot be obtained. The slag penetration resistance effect of the alumina-chromia is not sufficiently exhibited. As a result, this type of conventional amorphous refractory for a waste melting furnace is never satisfactory in its durability.
[0014]
The operating conditions of waste melting furnaces are becoming harsher, and the present invention responds to this, and in order to respond to this, in the amorphous refractories for waste melting furnaces that require the use of a large amount of ultrafine chromium oxide powder, the conventional materials are further The object is to provide a material with excellent durability.
[0015]
[Means for Solving the Problems]
The amorphous refractory for the waste melting furnace of the present invention is 5 to 35% by mass of ultrafine chromium oxide powder, with the balance being 100% by mass of the refractory raw material composition mainly composed of alumina aggregate and / or alumina-containing aggregate. One or two or more Ca compounds 0.01 to 1% by mass selected from slaked lime, lime, calcium carbonate, calcium chloride or calcium lactate, and a carboxyl group-containing polyether dispersant and binder are added on the outside It is characterized by.
[0016]
The amorphous refractory according to the present invention, when used as a lining of a waste melting furnace, forms a dense alumina-chromia sintered body as compared with a conventional material, and its durability is remarkably improved. The reason is considered as follows.
[0017]
Various dispersants are conventionally known for use in amorphous refractories. For example, organic dispersants such as general sodium polyacrylate are adsorbed on the surface of refractory fine powder during construction of irregular refractories, and an adsorption layer that repels fine particles is formed on the surface of refractory fine powder. However, in the amorphous refractory using chromium oxide ultrafine powder as described above, sufficient fluidity imparting effect cannot be obtained.
[0018]
On the other hand, the present invention uses a carboxyl group-containing polyether compound as a dispersant. The carboxyl group-containing polyether-based dispersant has a long ethylene oxide chain, and has a dispersing action due to a large steric repulsion effect of the long ethylene oxide chain. However, in the case of an amorphous refractory containing ultrafine chromium oxide powder, the adsorption rate to the chromium oxide particles is slow. Therefore, the steric repulsion of the ethylene oxide chain is sufficient by simply using a carboxyl group-containing polyether dispersant. It is not utilized and is inferior in the effect of imparting fluidity like other dispersants such as sodium polyacrylate.
[0019]
In the present invention, a Ca compound is further added together with the carboxyl group-containing polyether dispersant. The Ca compound elutes Ca ²⁺ ions in the solution and accelerates the adsorption rate to the chromium oxide particles, thereby promoting the steric repulsion of the ethylene oxide chain of the carboxyl group-containing polyether dispersant, and the flow of the amorphous refractory. Sexually improves.
[0020]
This carboxyl group-containing polyether-based dispersant is already known as an amorphous refractory dispersant, but in the present invention, it is low in an amorphous refractory containing a large amount of ultrafine chromium oxide powder in combination with a Ca compound. Construction with moisture becomes possible, and a dense construction body is obtained. As a result, the amorphous refractory according to the present invention forms a dense and strong alumina-chromia sintered body at a high temperature during use, and is used for slag containing alkali and chlorine such as sodium and chlorine peculiar to waste melting furnaces. Excellent corrosion resistance.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
In the amorphous refractory of the present invention, the chromium oxide ultrafine powder is not particularly different from that used in conventional amorphous refractories for waste melting furnaces. The purity is preferably 95% by mass or more of Cr ₂ O ₃ . The average particle diameter is, for example, about 0.1 to 10 μm as measured by a laser diffraction particle size measuring apparatus. More preferably, the average particle size is 0.5 to 5 μm.
[0022]
The ratio of the ultrafine chromium oxide powder is 5 to 35% by mass based on the total composition of the refractory raw material. More preferably, it is 10-30 mass%. If it is less than this, the slag penetration resistance is inferior, and the corrosion resistance effect of the present invention cannot be obtained.
[0023]
The aggregate is mainly composed of alumina aggregate and / or alumina-containing aggregate. Specific examples of the alumina aggregate are electrofused alumina, sintered alumina, bauxite and the like. Specific examples of alumina-containing aggregates are electrofused or sintered alumina-chromia and / or alumina-chromia-zirconia. If these aggregates are the same in terms of ingredients, the refractory waste material may be crushed and used.
[0024]
Alumina-chromia and alumina-chromia-zirconia have an effect of improving corrosion resistance depending on the chromia component contained in the aggregate itself. Further, as a supply source of the chromia component, an electrofused chromia may be combined with a part of the refractory aggregate.
[0025]
For the fine powder portion, calcined alumina that is easily available as fine powder may be used. Calcinated alumina is a fine powder obtained by firing aluminum hydroxide obtained by the Bayer method in a low temperature range. The proportion of the calcined alumina in the refractory raw material is preferably 25% by mass or less, more preferably 1 to 15% by mass. When the amount is too large, it is difficult to obtain a tightly packed structure from the balance of the particle size configuration of the entire amorphous refractory, which causes a decrease in corrosion resistance.
[0026]
The effect of the present invention can be obtained as long as the chromium oxide source is within a range in which ultrafine chromium oxide powder is limited in the present invention. More preferably, in the chemical component of the entire amorphous refractory composition including ultrafine chromium oxide powder, Cr ₂ O The ratio of ₃ is 10 mass% or more, More preferably, it is 20-90 mass%. When there are few chromia sources, it is inferior in the corrosion resistance with respect to the slag component peculiar to a waste melting furnace.
[0027]
The particle size of the above refractory aggregate is adjusted to a coarse particle, a medium particle, and a fine particle within the range so that the maximum particle size is, for example, about 5 to 10 mm so that a densely packed structure is obtained.
[0028]
For example, the chromium oxide ultrafine powder may be granulated or roughened to obtain a chromium oxide powder having a large particle size, and may be used as a chromia source together with the chromium oxide ultrafine powder essential for the present invention. However, it is not preferable in terms of economy because the cost is increased due to the trouble of granulating or roughening the chromium oxide powder.
[0029]
As long as the effects of the present invention are not impaired, zircon, zirconia, magnesia, dolomite, spinel, carbon and the like may be further combined as a refractory raw material. In order to improve the spalling resistance, for example, coarse particles having a particle size of 10 to 50 mm may be combined.
[0030]
The Ca compound is slaked lime, lime, calcium carbonate, calcium chloride or calcium lactate. These are all used as fine powder or ultra fine powder. Moreover, you may add in the state of lime milk.
[0031]
The addition amount of the Ca compound is 0.01 to 1% by mass, and more preferably 0.05 to 0.8% by mass, based on 100% by mass of the refractory raw material composition. If it is less, the effect of the present invention cannot be obtained in providing fluidity. A reaction product of Ca compound and chromia (CaCrO ₄ ) is a low-melting substance, and if the amount of Ca compound is large, the amount of the low-melting substance becomes excessive and the corrosion resistance is lowered.
[0032]
The carboxyl group-containing polyether dispersant may be used in either powder or liquid form. The liquid state is, for example, dispersed or dissolved in water or the like. The addition amount is not particularly different from the case of the dispersant in the conventional material, and is preferably 0.01 to 0.8% by mass, more preferably 0.05 to 0.6% by mass with respect to 100% by mass of the refractory raw material composition. %. When used in liquid form, this ratio is a solid content conversion value.
[0033]
When the amount of the carboxyl group-containing polyether dispersant is small, the effect of imparting fluidity is insufficient, and when too large, the workability is inferior due to the delay in curing.
[0034]
This carboxyl group-containing polyether dispersant can be obtained from commercially available products, for example, as Tight Rock (registered trademark) or Mighty (registered trademark) manufactured by Kao Corporation.
[0035]
Examples of the binder include alumina cement, phosphate, silicate, magnesia cement and the like. Alumina cement is preferable from the viewpoint of the strength of the construction body. The addition amount of the binder is preferably 1 to 10% by mass on the basis of 100% by mass of the refractory raw material composition.
[0036]
If necessary, the amorphous refractory of the present invention may further contain metal powders such as Al and Si, organic fibers, curing regulators, aluminum lactate, glass, and drying accelerators.
[0037]
For the construction, water is added to the above composition of the irregular refractory composition and added in an amount of about 3.5 to 6% by mass, followed by pouring using a mold. When pouring, filling is performed by applying vibration. Curing and drying after construction.
[0038]
Further, in addition to pouring directly into the furnace, the precast block that has been dried and poured into a mold at another place may be lined in the furnace.
[0039]
【Example】
Examples of the present invention and comparative examples thereof will be described below. At the same time, the test results of each example are shown. Table 1 shows the chemical component values of the alumina used in each example by X-ray fluorescence analysis (JIS R2216), Table 2 shows examples of the present invention, and Table 3 shows comparative examples.
[0040]
[Table 1]

[Table 2]

[Table 3]

Tight Rock (registered trademark) P-100 manufactured by Kao Corporation was used as the carboxyl group-containing polyether dispersant.
[0041]
In each example, the blended composition of the irregular refractories shown in the table was kneaded with a mixer and then poured into a metal mold. When pouring, the formwork was vibrated to promote the filling of the construction body. Subsequently, it was cured for 24 hours, and after demolding, it was dried at 110 ° C. for 24 hours to obtain a test piece of 40 × 40 × 160 mm in length. The test method is as follows.
[0042]
Bulk specific gravity: Measured according to JIS R2205.
[0043]
Strength: The test piece was further calcined at 1400 ° C. for 3 hours, and then measured with bending strength according to JIS R2553.
[0044]
Corrosion resistance: A rotary erosion test was conducted at 1650 ° C. for 20 hours using slag discharged from the gasification melting furnace (CaO / SiO ₂ : 0.74 in mass ratio) as an erodant. The erosion dimension was measured and indicated by an index with the erosion dimension of Comparative Example 1 being 100. It shows that it is excellent in corrosion resistance, so that a numerical value is small.
[0045]
Actual machine test: Lined in a gasification melting furnace with a daily waste treatment amount of 100 t, and measured the wear rate (mm / month) after 12 months of use. The operating temperature of this gasification melting furnace is 1400 ° C., and its slag component is mass%, SiO ₂ : 42.8, CaO: 31.7, Al ₂ O ₃ : 12.4, Fe ₂ O ₃ : 4.8. , Na ₂ O: 3.7, (CaO / SiO ₂ : 0.74).
[0046]
As the test results show, all of the examples of the present invention have a small amount of added water at the time of construction, and can form a dense construction body according to the measured value of bulk specific gravity. As a result, both the strength and the corrosion resistance after firing at 1400 ° C. assuming the use of the refractory in the waste melting furnace exhibit excellent effects.
[0047]
On the other hand, in Comparative Example 1 and Comparative Example 2, the dispersant is different from that of the present invention, and the Ca compound is not added, and the amount of added water is large in order to ensure the fluidity at the time of construction. Inferior in strength and as a result, inferior in strength and corrosion resistance.
[0048]
Comparative Example 3 uses a carboxyl group-containing polyether dispersant, but is inferior in fluidity at the time of construction because no Ca compound is added, and has increased strength and corrosion resistance by increasing the amount of water added to ensure fluidity. Inferior to
[0049]
In Comparative Example 4, although the amount of ultrafine chromium oxide powder used is small and a dense construction body can be formed even if the amount of added water is small, the corrosion resistance is poor due to insufficient chromia. In Comparative Example 5, the amount of ultrafine chromium oxide powder used is too large, the dispersibility is poor, and a large amount of added water is required, so that the strength and corrosion resistance are poor.
[0050]
In Comparative Example 6, slaked lime is added, but the dispersant is sodium polyacrylate, and since the fluidity is inferior, the amount of added water is increased, a dense construction body cannot be obtained, and the strength and corrosion resistance are inferior. In Comparative Example 7, the amount of slaked lime added as a Ca compound is too large, and the corrosion resistance is poor.
[0051]
In addition, as an amorphous refractory for a waste melting furnace of the present invention, the excellent effect of corrosion resistance is confirmed in the results of an actual machine test in a gasification melting furnace.
[0052]
【The invention's effect】
The refractory material of the present invention exhibits excellent durability as shown in the test results of the above examples against the slag component specific to the waste melting furnace caused by alkali and acid from the waste component. In recent years, waste melting furnaces such as municipal waste incinerators and gasification melting furnaces have become harsh due to their high-temperature operation, and the present invention has extremely high industrial value as a refractory that can cope with this. high.

Claims (5)

Chromium oxide ultrafine powder of 5 to 35% by mass, the balance being 100% by mass of refractory raw material mainly composed of alumina aggregate and / or alumina-containing aggregate, slaked lime, lime, calcium carbonate, calcium chloride or lactic acid An amorphous refractory for a waste melting furnace to which 0.01 to 1% by mass of one or more Ca compounds selected from calcium, a carboxyl group-containing polyether dispersant and a binder are added. The amorphous refractory for a waste melting furnace according to claim 1, wherein the alumina-containing aggregate is alumina-chromia and / or alumina-chromia-zirconia. The refractory material composition for waste melting furnace according to claim 1 or 2, wherein the refractory raw material composition further contains 25% by mass or less of calcined alumina. A waste melting furnace lined with an irregular refractory for a waste melting furnace according to any one of claims 1 to 3. The waste melting furnace according to claim 4, wherein the waste processing furnace is a furnace that generates clinker, ash, or slag having a component of CaO / SiO ₂ : 0.3 to 1.5 by mass ratio during operation. Furnace.