JP2018177570A - Anchor brick - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anchor brick which has sufficient hot strength, is prevented from breaking, and can be used for a long time even when used in a ceiling structure of a heating furnace in which the temperature inside the furnace reaches 1300 to 1400 ° C. Offer. SOLUTION: An anchor brick composed of a poured fireproof material and a metal fiber dispersed in the poured fireproof material is 20, and the content of the metal fiber operates from an end portion of the anchor brick 20 on the back surface side. It changes continuously or stepwise so as to decrease in the length direction toward the end on the surface side, and the content of the metal fiber at the end on the back surface side is 4 to 8% by mass. Anchor brick 20 having a metal fiber content of 1% by mass or less at the end on the working surface side. [Selection diagram] FIG. 1 (a)

Description

  The present invention relates to an anchor brick used in a ceiling structure of a kiln such as a furnace.

  In the ceiling structure of a furnace such as a heating furnace, the anchor brick is held at one end of the inner side surface of the casing, and embedded in a monolithic refractory layer formed laminated on the inner side and used. Prevent falling of refractory.

  However, since the anchor brick is held inside the casing by, for example, a hanger hardware, when the thermal stress from the inside of the furnace or the stress due to vibration is applied, a crack occurs in the held portion and it is finally broken. As a result, there is a problem that the roof can not support the monolithic refractories, and the ceiling may be dropped.

  Then, the technique for preventing breakage of an anchor brick is conventionally proposed.

  In Patent Document 1 (Japanese Patent Application Laid-Open No. 62-245082), a member for adjusting the upper and lower positions of the hanger hardware is inserted between the hanger hardware supporting the anchor brick and the suspension pipe in the kiln furnace ceiling. There is disclosed a method of preventing breakage and removal of anchor bricks by suspending loads from the anchor bricks by equalizing the load applied to each anchor brick. However, the method disclosed in Patent Document 1 has a problem that the construction becomes complicated because it is necessary to adjust the anchor bricks with members so that the lower surfaces of the anchor bricks are aligned at a predetermined horizontal position.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 10-310478) contains 2 to 5% by weight of a stainless steel fiber having a length of 10 to 30 mm and is manufactured using a low cement castable and is not used for a refuse incinerator ceiling Firing anchor bricks are disclosed, and it is described that the inclusion of stainless steel fibers improves the material of the anchor bricks, greatly improves the hot strength, and suppresses the occurrence of cracks during operation. . However, although the anchor brick disclosed in Patent Document 2 is sufficiently effective when used in a refuse incinerator with an in-furnace temperature of 900 to 1000 ° C., the in-furnace temperature reaches 1300 to 1400 ° C. It has been found that when used in a heating furnace, the structure of the anchor brick weakens and reduces the hot strength.

Japanese Patent Application Laid-Open No. 62-245082 Japanese Patent Application Laid-Open No. 10-310478

  Therefore, the object of the present invention is to have sufficient hot strength and prevent breakage even when used in the ceiling structure of the furnace where the temperature in the furnace reaches 1300 to 1400 ° C., and it is used for a long time Is to provide a possible anchor brick.

  The inventors of the present invention have developed an anchor brick structure which is generated when an anchor brick containing metal fiber as disclosed in Patent Document 2 is used at the ceiling of a heating furnace whose temperature in the furnace reaches 1300 to 1400 ° C. The cause of vulnerability was considered as follows.

  In a ceiling structure such as a heating furnace, when the heating furnace is in operation, the environmental temperature on the working surface side (in-furnace temperature) is about 1300 to 1400 ° C., and the environmental temperature on the back side is about 60 ° C. The temperature of the anchor brick at that time is 1000 ° C. or higher on the working surface side and about 600 ° C. on the rear surface side. If the working surface anchor brick continues to be heated to 1000 ° C. or more, it is considered that the metal fibers contained in the anchor brick will be oxidized, and as a result, the structure of the anchor brick will be weakened with the passage of time and heat It is thought that it may reduce the in-between strength.

  The present inventors focused attention on the occurrence of a temperature gradient from the working surface side (inside of the furnace) to the back side (suspended side), and as a result of keen research, metal fibers as disclosed in Patent Document 2 were The anchor brick is configured so that the amount of metal fiber added decreases continuously or gradually from the back side to the working surface instead of the uniformly contained anchor brick, and the temperature is 1000 ° C. or more on the working surface By reducing the metal fiber content of the heated part as much as possible, it is possible to avoid the weakening of the tissue due to oxidation, and maximize the effect of metal fiber addition in the part to which stress is applied by the hanger etc. on the back side. Having found what can be done, the present invention was conceived.

  That is, the anchor brick of the present invention comprises a cast refractory and metal fibers dispersed in the cast refractory, and the content of the metal fiber is from the end on the back side of the anchor brick to the working surface Continuously or gradually changing so as to decrease in the longitudinal direction toward the end of the fiber, and the content of the metal fiber at the end on the back side is 4 to 8% by mass; Content of the said metal fiber in the edge part by the side of a surface is characterized by being 1 mass% or less.

  The anchor brick has at least three regions in which the content of the metal fiber is different in the length direction of the anchor brick, and the content a of the metal fiber in the region A on the end side on the back side is 4 to 8% by mass The content b of the metal fiber in the region B on the end side of the working surface is 1% by mass or less, and the content of the metal fiber in the region between the region A and the region B is More than b% by weight and less than a% by weight are preferred.

  The region A preferably includes a region which is 600 ° C. ± 100 ° C. in use, and the region B preferably includes a region which is 1000 ° C. or more in use.

  The metal fibers preferably have a cross-sectional maximum diameter of 0.2 to 1.5 mm and a length of 20 to 35 mm.

  The cast refractory preferably comprises refractory aggregate, refractory fine powder, alumina cement and a dispersant.

  The anchor brick of the present invention can prevent the weakening of the brick structure due to the oxidation of the metal fiber on the working surface side (furnace inside), so the hot strength at any location in the longitudinal direction of the anchor brick There is no drop in the weight, and the effect of metal fiber addition can be maximized. Therefore, it is suitable for use of the ceiling part of the heating furnace in which a furnace temperature reaches 1300-1400 degreeC.

It is a perspective view which shows typically an example of ceiling structures, such as a heating furnace etc. which used the anchor brick of this invention. It is sectional drawing of the ceiling structure shown to Fig.1 (a). It is a perspective view showing an anchor brick of the present invention typically. It is a perspective view which shows typically another example of ceiling structures, such as a heating furnace using the anchor brick of this invention. It is sectional drawing of the ceiling structure shown to Fig.3 (a). It is an anchor brick of this invention, Comprising: It is a schematic cross section which shows a mode that content of a metal fiber is changing to (a) continuous and (b) in steps. It is sectional drawing which shows the example of the shape ((a) mountain shape, (b) waveform, and (c) dog bone shape) of the metal fiber which can be used with the anchor brick of this invention. It is a schematic cross section of (a) 2 steps | paragraphs and (b) 3 steps | pieces of anchor bricks produced in the Example.

  Hereinafter, modes for carrying out the present invention will be described.

[1] Ceiling Structure of Heating Furnace etc. The anchor brick of the present invention is used by being embedded in a monolithic refractory layer in a ceiling structure such as a heating furnace, and supports and fixes the monolithic refractory layer. A ceiling structure 10 such as a heating furnace comprises an anchor brick 20 and a monolithic refractory 30 surrounding the anchor brick, as shown in FIGS. 1 (a) and 1 (b). The monolithic refractory 30 is supported and fixed to the casing 40 by the upper end portion 21 being held by the anchor metal 50 provided on the inner side surface of the ceiling portion of the casing 40 formed of iron skin or the like. The anchor brick 20 is a pillar having a groove 22 formed in a direction orthogonal to the longitudinal direction as shown in FIG. 2 and when the anchor brick 20 is used by being embedded in the monolithic refractory 30, The fixed refractory 30 bites into the groove 22 to hold the fixed refractory 30 and prevent it from falling off.

  Fig.3 (a) and FIG.3 (b) show an example of the ceiling structure 11 of a heating furnace etc. which do not have the casing formed of iron skin etc. FIG. Instead of being held by the anchor metal 50 provided on the inner side surface of the ceiling portion of the casing 40, the anchor brick 20 is suspended and supported by a wire 70 or the like on a beam 60 provided on the ceiling portion of a heating furnace or the like.

  As described above, when used for a ceiling structure such as a heating furnace, the temperature of the anchor brick is 1000 ° C. or more on the working surface side and about 600 ° C. on the back surface side. Generally, in cast refractories using a hydraulic binder, the hydraulic binder decomposes from 300 ° C. or higher to form fine pores, and when the temperature rises to 1000 ° C. or higher, the matrix portion is sintered, and fine Express their strength while reducing various pores. Therefore, at about 600 ° C., the hydraulic binder in the matrix is decomposed to have fine pores but the sintering is not in progress. Therefore, since the back surface side portion at around 600 ° C. is in a non-sintered state, its strength is lower than that of the working surface side being sintered.

[2] anchor brick
(1) Configuration The anchor brick of the present invention comprises a cast refractory and metal fibers dispersed in the cast refractory, and the content of the metal fiber is operated from the end on the back side of the anchor brick It is characterized in that it changes continuously or stepwise so as to decrease in the longitudinal direction toward the end on the surface side.

  Since the metal fiber significantly accelerates oxidation in a temperature environment of 1000 ° C. or more, it is preferable to reduce the amount of metal fiber contained in the portion of the working surface side to a temperature of 1000 ° C. or more as much as possible. As mentioned above, since the matrix contained in the cast refractory is sintered at a temperature of 1000 ° C. or higher on the working surface side and high strength is developed, even if the amount of metal fiber added is reduced It can maintain practical strength. The content of the metal fibers in the working surface side, in particular, the portion where the temperature at the time of operation is 1000 ° C. or more, is 1% by mass or less. If the content exceeds 1% by mass, the hot strength may be reduced due to the oxidation of the metal fiber, and the anchor brick may be broken. The content of the metal fiber is more preferably 0.5% by mass or less. The metal fiber may not be contained in the portion where the temperature at the time of operation is 1000 ° C. or more.

  On the other hand, since the temperature on the back side of the anchor brick is about 600 ° C. and oxidation of metal fibers does not occur, a sufficient amount of metal fibers can be contained to improve the hot strength of the anchor brick. Content of the metal fiber of a back side, especially the part of temperature 600 degreeC +/- 100 degreeC at the time of operation | use shall be 4-8 mass%. If the content is less than 4% by mass, the hot strength is low and there is a risk of breakage from the portion held by the hanger hardware, and if it exceeds 8% by mass, the amount of water required for kneading increases and the hot strength decreases May be broken from the part held by the hanger hardware.

  Furthermore, since the anchor brick is held by the anchor metal 50 or the wire 70 at the back side portion as described in FIGS. 1A and 3A, stress concentrates on the holding portion, and the portion Cracks are likely to occur from Thus, the strength of the cast-in refractory is low, and the effect of the metal fiber is particularly exhibited in the portion on the back side where the stress is concentrated.

  The content of the metal fiber may be continuously changed from the back surface side 120a to the operation surface side 120b as shown in FIG. 4A, and as shown in FIG. 4B, the back surface side 220a The region A, the region M, and the region B may be changed stepwise in the order from the region A to the operation surface 220b. Although FIG. 4B shows the anchor brick 220 in which the content of the metal fiber 223 is changed in three steps, as described later, it may be changed in two steps, or in four or more steps. It may be changing.

  When the content of the metal fiber changes continuously, from the end on the back side (the end that will be the back side during use) to the end on the working surface side (the end that becomes the working side during use) Preferably, the metal fiber content is reduced monotonously (e.g., linearly).

  When the content of the metal fiber changes stepwise, it may be two steps of high content and low content, but it is preferable to change by three or more steps. For example, when the content of the metal fiber is changed in three steps, as shown in FIG. 4B, the content a of the metal fiber in the region A on the end side of the back side 220a, the end of the operation side 220b Preferably, the content c of the metal fiber in the region B on the part side and the content b of the metal fiber in the region M between the region A and the region B satisfy the relationship a> b> c . Similarly, in the case of four or more stages, it is preferable that the metal fiber content be reduced stepwise from the end on the back side to the end on the working surface side.

  Even when the content of the metal fiber changes continuously or stepwise, the content of the metal fiber at the end on the back side is 4 to 8% by mass, and the metal at the end on the working surface side The content of the fiber is 1% by mass or less. Here, the content of the metal fiber at the end on the back surface side or the working surface side is the amount included in the region between the end surface and the position at 10% in the length direction from the end surface.

(2) Cast Refractory The cast refractory constituting the anchor brick is preferably made of the same material as the monolithic refractor surrounding the anchor brick in order to reduce the thermal stress from the inside of the furnace. As an example, castable refractory surrounding the anchor brick For A1 ₂ 0 ₃ -SiO ₂ quality plastic refractories, using the pouring refractory of the same material.

  The refractory formulation used for the cast refractory preferably comprises refractory aggregate, refractory fines, alumina cement and a dispersant.

  As the refractory aggregate, substantially spherical electromelted and sintered products used for general cast refractories can be used, and the particle size thereof is 10 mm or less. The composition is selected from the group consisting of alumina, bauxite, kayanite, andalusite, mullite, chamotte, rhodolite, silica stone, alumina-magnesia spinel, magnesia, zircon, zirconia, silicon carbide, graphite, carbon, pitch and the like. And, if necessary, two or more can be used in combination.

  Similarly, the refractory fine powder is at least one selected from the group consisting of amorphous silica fine powder, silica fine powder, alumina fine powder, magnesia fine powder, titania fine powder, mullite fine powder, zirconia fine powder, chromia fine powder, silicon carbide fine powder, carbon fine powder and the like. It is a species, and two or more species are used in combination as needed. In addition, the fireproof fine powder here is a particle | grain of 200 mesh or less, ie, 0.074 mm or less, by a JIS standard sieve.

  As the alumina cement, a high purity high alumina cement having a CaO content of less than 30% by mass and containing calcium aluminate as a main component is used.

  The dispersant is not particularly limited, but inorganic dispersants such as tripolyphosphate, hexametaphosphate, ultrapolyphosphate, acidic hexametaphosphate, polyacrylate, sulfonate, polycarboxylic acid Use an organic dispersant such as a system.

  In addition to the above-mentioned constitution, a thickener, a hardening control agent, an explosion-cracking agent, etc. can be added to the refractory composition in addition to the above-mentioned composition to the cast refractory, in the range which does not inhibit the effect of the invention. .

(3) Metal fiber Any metal fiber may be used as long as it is generally used for cast refractories, as long as the effect of the present invention is not impaired. In particular, if highly oxidation resistant metal fibers are used, the anchor brick of the present invention can be either a fired brick or an unfired brick. By incorporating metal fibers in the cast-in refractory, it is possible to significantly improve the hot strength of the anchor brick and to suppress the occurrence of cracking during operation.

  The metal fiber has a maximum cross-sectional diameter of 0.2 to 1.5 mm. If the cross-sectional maximum diameter is less than 0.2 mm, the effect of improving the hot strength of the anchor brick can not be obtained, and if it exceeds 1.5 mm, the flowability of the cast refractory decreases, and the fillability at the construction becomes worse. The length of the metal fiber is more preferably 20 to 35 mm. If the length is less than 20 mm, the effect of dispersing or suppressing cracks at less than 1000 ° C. can not be obtained, and if the length is more than 35 mm, the metal fibers tend to be entangled during kneading, and the flowability of cast refractory decreases It is not preferable because the resulting organization becomes fragile.

  The type of metal fiber is not particularly limited, and any metal fiber generally used for cast refractories can be used. For example, heat resistant alloys, heat resistant steels, stainless steels, high tensile steels, carbon steels may be mentioned, and they contain one or more elements such as Cu, Al, Mo, Ti, Nb, Be, N, B, etc. Special alloy steel etc. are also mentioned. As comparatively easy to obtain, SUS310S, SUS304, SUH446, SUS430, etc. which are standardized by JIS can be mentioned.

  As the shape of the metal fiber, any of linear and curvilinear shapes (eg, chevron, corrugation, dog bone shape, etc.) as shown in FIG. 5 can be used as long as the effects of the present invention are not impaired.

  The present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

(1) Experimental Example A refractory aggregate, refractory fine powder, alumina cement and metal fiber were blended to prepare a cast refractory consisting of 65 mass% of Al ₂ O ₃ and 35 mass% of SiO ₂ in chemical composition. The metal fiber was made of SUS304 and used in a linear form having a maximum diameter of 0.5 mm and a length of 15 mm.

  The cast refractory was kneaded with water in the amount shown in Table 1, cast into a 40 × 40 × 160 mm mold, molded for 24 hours at normal temperature, removed from the frame and dried at 110 ° C. for 24 hours. The obtained molded product was dried and then heated at 600 ° C. and 1000 ° C. for 3 hours, and then the physical properties were measured. The test method of each test is described below.

(1-1) Residual line change rate
It measured based on JIS R2654.

(1-2) Bulk specific gravity
It measured based on JIS R2655.

(1-3) Thermal conductivity
It was measured in accordance with JIS R 2251-1 (heat ray method: orthogonal method).

(1-4) Hot bending strength
It measured based on JISR2553.

※ 耐火性原料100質量％に対する外割添加水量

※ The amount of externally added water added to 100% by mass of refractory material

(2) Example and Comparative Example Example 1
Using the cast refractories of Experimental Example 3 and Experimental Example 6 produced in the experimental examples, as shown in FIG. 6A, the amount of metal fibers in the region A of 100 mm from the working surface side 300b is 1 mass% (experiment Anchor brick 300 (width 125 mm) of the shape shown in FIG. 2 which is the cast refractory of Example 3 and the amount of metal fiber in the region B of 100 mm to 350 mm is 8% by mass (cast refractory of Experimental example 6) And a length of 350 mm), and as shown in FIG. 1 (a), it was installed on the ceiling of the heating furnace.

Example 2
Using the cast refractories of Experimental Example 2, Experimental Example 4 and Experimental Example 6 prepared in the experimental examples, as shown in FIG. 6 (b), the amount of metal fiber in the region a of 50 mm from the working surface side 400b is 0.5 Mass% (the poured refractory of Experimental Example 2), the amount of metal fibers in the region b of 50 mm to 200 mm is 3 mass% (the poured refractory of Experimental Example 4), the region c of 200 mm to 350 mm An anchor brick 400 (125 mm in width, 350 mm in length) having the shape shown in FIG. 2 and having a metal fiber content of 8% by mass (the cast refractory of Experimental Example 6) is produced, as shown in FIG. Installed on the ceiling of the heating furnace.

Comparative Example 1
Using the cast fire resistances of Test Examples 2 and 4 instead of the cast refractories of Test Example 3 and Test Example 6, the amount of metal fibers in the region A is 0.5% by mass (the cast refractories of Test Example 2) An anchor brick is produced in the same manner as in Example 1 except that the amount of metal fiber in the region B is 3% by mass (the cast refractory of Experimental Example 4), and the ceiling of the heating furnace as shown in FIG. Installed in

Comparative example 2
Using the cast fire resistances of Test Examples 2 and 7 instead of the cast refractories of Test Examples 3 and 6, respectively, the amount of metal fiber in the region A is 0.5% by mass (the cast refractories of Test Example 2) An anchor brick is produced in the same manner as in Example 1 except that the amount of metal fiber in the region B is set to 10% by mass (the cast refractory of Experimental Example 7), and as shown in FIG. Installed in

Comparative example 3
Using the cast refractory of Experimental Example 4 instead of the cast refractory of Experimental example 3, the amount of metal fibers in region A is 3% by mass (the cast refractory of Experimental example 4) and the amount of metallic fibers in region B is 8 An anchor brick was produced in the same manner as in Example 1 except that it was made by mass% (the poured refractory of Experimental Example 6), and was installed on the ceiling of the heating furnace as shown in FIG. 1 (a).

  A portion of the ceiling portion after the cast refractories used in each region of the anchor bricks of Examples 1 and 2 and Comparative Examples 1 to 3 and the heating furnace having the anchor bricks installed on the ceiling portion for about one year The side surface of each anchor brick was exposed by disassembling, and visual inspection was performed, and those without breakage were evaluated as ○, and those with breakage observed were evaluated as ×. The results are shown in Table 2.

注(1)：金属ファイバー量の数値の下に記載した実験例は、流し込み耐火物の実験例番号を示す。
注(2)：２段のアンカーれんがは稼動面側から領域A及びBの構成であり、３段のアンカーれんがは稼動面側から領域a、b及びcの構成である。

Note (1): The experimental example described under the numerical value of the metal fiber amount shows the experimental example number of the cast refractory.
Note (2): The two-tiered anchor brick has the configuration of areas A and B from the working surface side, and the three-tiered anchor brick has the configuration of areas a, b and c from the working surface side.

  As is apparent from Table 2, the anchor bricks of the present invention, Examples 1 and 2, use appropriate amounts of metal fibers at each site, so breakage is not observed at any site. And the addition effect of metal fiber was able to be exhibited to the maximum.

  On the other hand, Comparative Example 1 in which the metal fiber on the back side was less than 4% by mass was broken from the portion held by the hanger metal because of the low hot strength. In Comparative Example 2 in which the metal fiber on the back side was more than 8% by mass, the portion held by the hanger metal was broken because the amount of kneading water was large and the hot strength was lowered. In Comparative Example 3 in which the metal fiber on the working surface side is more than 1% by mass, the metal fiber is oxidized during use and the hot strength is lowered, so the working surface side is broken.

1 ・ ・ ・ Ceiling structure
2 ・ ・ ・ Ceiling structure
20 ・ ・ ・ Anchor brick
21 ... top end
22 ・ ・ ・ Groove
23 ・ ・ ・ metal fiber
30 ··· Undefined refractory
40 ... casing
50 ・ ・ ・ Anchor metal
60 ・ ・ ・ Hanging pipe
70 · · · Hanger hardware
120, 220 ... anchor brick
120a, 220a ... back side
120b, 220b ... active side
122, 222 ... groove
123, 223 ... metal fiber
300, 400 ... anchor brick
300a, 400a ... back side
300b, 400b ... working side

Claims (5)

  An anchor brick comprising a cast refractory and metal fibers dispersed in the cast refractory, wherein the content of the metal fiber is from the end on the back side of the anchor brick to the end on the working surface side The metal fiber content in the back end is 4 to 8% by mass so as to decrease in the longitudinal direction, and the end on the working surface side Content of the said metal fiber in a part is 1 mass% or less, The anchor brick characterized by the above-mentioned.   In the anchor brick according to claim 1, it has at least three fields where contents of said metal fiber differ in the length direction of said anchor brick, and said metal fiber in field A of the end by the side of said back side Content a of the metal fiber is 4 to 8% by mass, the content b of the metal fiber in the area B on the end side of the working surface side is 1% by mass or less, and between the area A and the area B Content of the said metal fiber in area | region of b is more than b mass% and less than a mass%, The anchor brick characterized by the above-mentioned.   The anchor brick according to claim 2, wherein the region A includes a region that is 600 ° C. ± 100 ° C. in use, and the region B includes a region that becomes 1000 ° C. or more in use.   Anchor brick according to claims 1 to 3, characterized in that said metal fibers have a maximum cross-sectional diameter of 0.2 to 1.5 mm and a length of 20 to 35 mm.   The anchor brick according to any one of claims 1 to 4, wherein the cast refractory comprises a fireproof aggregate, a refractory fine powder, an alumina cement and a dispersant.

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