Monday, December 28, 2015
Bonded Again Fused Cast Alumina Block
Bonded again fused cast alumina block is a type of bonded again sintered refractory brick made of fused corundum clinker as the granular material and fused corundum or sintered corundum powder as the matrix.
When using fused brown corundum or white corundum as raw materials, the frits should be smashed and then processed by removing the ferro-silicon alloy and other impurities. White corundum should be processed by removing the flaky sodium aluminate crystals and other low-melting substances. The impurities are easy to be identified since they have low density and float in the surface of corundum frits.
There are a few harmful ingredients in the corundum which will cause poor sintering or cracking, so corundum should be pre-calcined before use. The residual ferro-silicon alloy is oxidized and decomposed into Fe2O3 and SiO2 at 500-1000℃ and Ti in the minerals can be oxidized into TiO2 (rutile), which can cause large volume expansion. After pre-calcining, the stress caused by those decomposition reactions and oxidation reactions can be eliminated during the pre-calcining process and cracks caused by the volume expansion of those impurities can be avoided during the sintering process.
Fused corundum block has large volume, so it should be smashed with drop hammers and other ways and then pulverized. The pulverized fused corundum is stored by size after screened. Fused corundum is hard and difficult to grind. Therefore it is wet ground by ball mills or vibration ball mills. The grain size can be less than 40μm or even 10μm. The iron in the granular material can be removed with electromagnets and the iron in the fine powder can be washed with acids.
The batching of granular materials should be according to the principles of tightly packing, multilevel ratio, less intermediate particles and more fine powder. This can improve the density and sintering of the products. The additives include aluminum phosphate, phosphoric acid, aluminum chromium phosphate, cellulose and pulp waste solution. Among them, he most promising is active phosphate. Recently, ammonium phosphate is on the trial and achieves good results. The mud should be mixed evenly with a moisture content of 3-4%. After high pressure molding, high dense bricks are obtained.
The fused cast alumina block has high purity. It is difficult to sintere and should be sintered at 1800℃. The type of the kilns used depends on the production scale. For small batch production, high-temperature batch kiln is better. For batch stable production, the small high-temperature tunnel kiln is used.
Zhengzhou Sunrise Refractory is a refractory supplier from China. We provide various refractory materials such as fused cast AZS, fused cast alumina block, silica brick, zircon brick, etc..
Sunday, December 27, 2015
The Cutting and Pre-Assembling of Fused Cast Alumina Block
The fuse cast alumina block is a kind of cast product with rough surface and big size tolerance. In actual use, in order to reduce the brick joints, factories machine it with diamond tools. This can save energy and prolong the service life of the furnace.
Fused cast alumina block can be divided into alpha-beta block, alpha block and beta block.
Alpha-beta fused cast Alumina Block is formed by the compact structure of alpha alumina and beta alumina crystals in a most ideal proportion which is approximately 50% and 50% respectively, where intertwined crystals of both materials result in a very dense structure. It has dense structure and no contamination to glass. It is the ideal refractory materials for channels, spouts and working ends of floating glass furnace.
Alpha fused cast alumina block is an ideal product for the lower temperature zones of the glass melting furnaces due to its high density, superior corrosion resistance and low blister potential. It is also an ideal material for Metallurgical Titanium Furnace because the superior thermal stability.
Beta fused cast alumina block comprises of a majority of beta alumina crystals and a slight portion of alpha alumina crystals in compact structure. Moreover, the intersected texture of large ß-alumina ensures great dimensional stability and great resistance against spalling. Its property of base saturation enables a higher resistance to alkali vapor, thus it has excellent thermal shock resistance and does not form molten droplets. It is the best material for molter crown, port crown, feeder channel, ect.
Recently, the mechanical processing technology of the refractory materials has seen development. The pre-assembling of the refractory materials has already been adopted aboard. After the products are processed, pre-assembled, numbered and accepted, it is transported from the factory. This can save the time of cold repair and hot repair.
Zhengzhou sunrise is a refractory supplier from China. We offers various refractory materials for glass furnaces, such as fused cast AZS, fused cast alumina block, fused cast high zircon block, etc..
Fused cast alumina block can be divided into alpha-beta block, alpha block and beta block.
Alpha-beta fused cast Alumina Block is formed by the compact structure of alpha alumina and beta alumina crystals in a most ideal proportion which is approximately 50% and 50% respectively, where intertwined crystals of both materials result in a very dense structure. It has dense structure and no contamination to glass. It is the ideal refractory materials for channels, spouts and working ends of floating glass furnace.
Alpha fused cast alumina block is an ideal product for the lower temperature zones of the glass melting furnaces due to its high density, superior corrosion resistance and low blister potential. It is also an ideal material for Metallurgical Titanium Furnace because the superior thermal stability.
Beta fused cast alumina block comprises of a majority of beta alumina crystals and a slight portion of alpha alumina crystals in compact structure. Moreover, the intersected texture of large ß-alumina ensures great dimensional stability and great resistance against spalling. Its property of base saturation enables a higher resistance to alkali vapor, thus it has excellent thermal shock resistance and does not form molten droplets. It is the best material for molter crown, port crown, feeder channel, ect.
Recently, the mechanical processing technology of the refractory materials has seen development. The pre-assembling of the refractory materials has already been adopted aboard. After the products are processed, pre-assembled, numbered and accepted, it is transported from the factory. This can save the time of cold repair and hot repair.
Zhengzhou sunrise is a refractory supplier from China. We offers various refractory materials for glass furnaces, such as fused cast AZS, fused cast alumina block, fused cast high zircon block, etc..
Monday, December 21, 2015
The Economy of Fused Cast Bricks in Glass Furnaces
Fused cast AZS block has been used in the checker work of the regenerator and the crown in the glass furnace.
Fused cast AZS block has excellent resistance to the erosion by fly ash to the checker brick in the regenerator, which is confirmed by its application in the burner. Fused cast AZS is durable than other bricks even it is only used in the upper layer of the checker work.
The performance of fused cast AZS block in the crown has been confirmed in the furnace with a small span. It shows excellent resistance. The new fused cast AZS crown structure as well as the insulation method developed by R.E.R from France has been used in the glass furnaces with a span of 11m and large furnaces. It is characterized by the use of light and firm magnetic structure and complete insulation with a 500mm insulation layer.
The limit temperature of silica brick crown is 1600℃, while the fused cast AZS block can be used safely in the 1680℃. AZS also has excellent corrosion resistance to fly ash and vapor of volatile components. Therefore, the temperature of the furnace can be increased to 100℃. Ina addition, there is a low risk of burning of materials. The crown is low, which increases the heat radiation and improve the melting rate and reduce the energy consumption.
Since 1965, the fused cast AZS crown has been used. The crown was initially built with common silica brick, mainly used in the glass fiber and borosilicate glass melting furnace. The fused cast AZS crown as well as the insulation method began to be actually used and its application was even expanded to large soda lime glass melting furnaces. In 1974, the structure was used in large cross-fired furnaces with a span of 11m. Besides, it is also used in the container glass furnace in France and can reduce 130 liters heavy oil per ton.
Zhengzhou Sunrise Refractory Co., Ltd. is a refractory supplier from China. We provide various refractories for glass furnaces, including fused cast AZS, fused cast alumina block, fused cast high zircon block, etc..
Fused cast AZS block has excellent resistance to the erosion by fly ash to the checker brick in the regenerator, which is confirmed by its application in the burner. Fused cast AZS is durable than other bricks even it is only used in the upper layer of the checker work.
The performance of fused cast AZS block in the crown has been confirmed in the furnace with a small span. It shows excellent resistance. The new fused cast AZS crown structure as well as the insulation method developed by R.E.R from France has been used in the glass furnaces with a span of 11m and large furnaces. It is characterized by the use of light and firm magnetic structure and complete insulation with a 500mm insulation layer.
The limit temperature of silica brick crown is 1600℃, while the fused cast AZS block can be used safely in the 1680℃. AZS also has excellent corrosion resistance to fly ash and vapor of volatile components. Therefore, the temperature of the furnace can be increased to 100℃. Ina addition, there is a low risk of burning of materials. The crown is low, which increases the heat radiation and improve the melting rate and reduce the energy consumption.
Since 1965, the fused cast AZS crown has been used. The crown was initially built with common silica brick, mainly used in the glass fiber and borosilicate glass melting furnace. The fused cast AZS crown as well as the insulation method began to be actually used and its application was even expanded to large soda lime glass melting furnaces. In 1974, the structure was used in large cross-fired furnaces with a span of 11m. Besides, it is also used in the container glass furnace in France and can reduce 130 liters heavy oil per ton.
Zhengzhou Sunrise Refractory Co., Ltd. is a refractory supplier from China. We provide various refractories for glass furnaces, including fused cast AZS, fused cast alumina block, fused cast high zircon block, etc..
Wednesday, December 16, 2015
Structure Types of Ceramic Fiber Lining
The ceramic fiber lining is mainly made up with ceramic fiber products such as ceramic fiber blanket, ceramic fiber module or ceramic fiber board. There are mainly two structure types of ceramic fiber lining: layer structure and tile stacking composite structure.
The layer-structure lining is built by putting ceramic fiber products on the steel sheet of the furnace wall layer by layer and then fixing them with heat-resistant steel anchors or in other ways. According to the lining material, the layer structure can be divided into two types: layer structure with ceramic fiber blanket and layer structure with ceramic fiber felt or board.
The layer structure with ceramic fiber blanket can be classified into butt type and lap type, according to the installation method of the hot face of the blanket. The felt or board is mostly installed in the butt type. Both the two types of layer structure can be classified into anchoring-nail-exposed style and anchoring-nail-embedded style according to the fixed way of anchoring nails.
The anchoring-nail-exposed structure is built by tilting the blanket, felt or board on the wall and then fixing it with anchoring nails, fast cards, rotary cards or nuts. Different materials can be used in the lining according to the temperature along the direction of the lining thickness. This structure can greatly reduce the construction cost, improve the insulation performance and is easy to construct and repair. The drawback is its poor resistance to wind erosion. Since the anchors are exposed in the hot face, when the temperature is high, it puts higher requirements on the anchors. The anchor itself is a heat conductor and the ceramic fiber board (blanket or felt) can generate volume shrinkage when use, which may cause gaps in the butt joints and weaken its insulation performance. Therefore, this structure is suitable to low-temperature heat treatment furnace.
The anchoring-nail-embedded style can avoid the exposing of the hot face of the anchoring nails, reduce the heat loss and improve the insulation performance. But it is difficult to overcome the poor resistance to wind erosion. Meanwhile, if it adopts ceramic-cup structure, the ceramic cup is brittle and expansive, which increases the construction difficulty and the cost. If it adopts sinking-hole structure, when the temperature changes, the sinking hole may generate shrinkage and cracks and damage the anchors. Therefore, it is only suitable to the insulation of the low temperature furnace wall.
Currently the tile stacking composite structure can be categorized into ceramic fiber module + tile structure and polycrystalline bar + module + tile structure (from hot face to cold face). Given the actual conditions such as the speed of the burner flame and the composition of the fuel gas, a layer of coating with good resistance to erosion and high temperature may be brushed on the hot face of the ceramic fiber lining. This coating can form a dense protective layer with good resistance to erosion and high temperature.
The thickness of the ceramic fiber lining is up to the structure of the heating devices (flat wall or curved wall), the thermal conductivity of the materials, the average temperature of the cold and hot face and allowed unit heat loss. The material should be selected by taking into consideration many factors including the maximum temperature, the working conditions, the fuel, the atmosphere and the pressure. The selection of the anchor should be based on the temperature of its location and whether it is in direct contact with fuel gas.
The installation arrangement ways of the modules can be divided into parquet floor type and soldier row type. The parquet floor type is a traditional installation arrangement way and was very popular a few years ago. However, with the development of the development of the applied technology of ceramic fiber module, research and practice have proved that, the parquet floor type has some drawbacks. Therefore, it is only used in the bar pasted structure of the hot face. Currently, most programs adopt the soldier row type.
The layer-structure lining is built by putting ceramic fiber products on the steel sheet of the furnace wall layer by layer and then fixing them with heat-resistant steel anchors or in other ways. According to the lining material, the layer structure can be divided into two types: layer structure with ceramic fiber blanket and layer structure with ceramic fiber felt or board.
The layer structure with ceramic fiber blanket can be classified into butt type and lap type, according to the installation method of the hot face of the blanket. The felt or board is mostly installed in the butt type. Both the two types of layer structure can be classified into anchoring-nail-exposed style and anchoring-nail-embedded style according to the fixed way of anchoring nails.
The anchoring-nail-exposed structure is built by tilting the blanket, felt or board on the wall and then fixing it with anchoring nails, fast cards, rotary cards or nuts. Different materials can be used in the lining according to the temperature along the direction of the lining thickness. This structure can greatly reduce the construction cost, improve the insulation performance and is easy to construct and repair. The drawback is its poor resistance to wind erosion. Since the anchors are exposed in the hot face, when the temperature is high, it puts higher requirements on the anchors. The anchor itself is a heat conductor and the ceramic fiber board (blanket or felt) can generate volume shrinkage when use, which may cause gaps in the butt joints and weaken its insulation performance. Therefore, this structure is suitable to low-temperature heat treatment furnace.
The anchoring-nail-embedded style can avoid the exposing of the hot face of the anchoring nails, reduce the heat loss and improve the insulation performance. But it is difficult to overcome the poor resistance to wind erosion. Meanwhile, if it adopts ceramic-cup structure, the ceramic cup is brittle and expansive, which increases the construction difficulty and the cost. If it adopts sinking-hole structure, when the temperature changes, the sinking hole may generate shrinkage and cracks and damage the anchors. Therefore, it is only suitable to the insulation of the low temperature furnace wall.
Currently the tile stacking composite structure can be categorized into ceramic fiber module + tile structure and polycrystalline bar + module + tile structure (from hot face to cold face). Given the actual conditions such as the speed of the burner flame and the composition of the fuel gas, a layer of coating with good resistance to erosion and high temperature may be brushed on the hot face of the ceramic fiber lining. This coating can form a dense protective layer with good resistance to erosion and high temperature.
The thickness of the ceramic fiber lining is up to the structure of the heating devices (flat wall or curved wall), the thermal conductivity of the materials, the average temperature of the cold and hot face and allowed unit heat loss. The material should be selected by taking into consideration many factors including the maximum temperature, the working conditions, the fuel, the atmosphere and the pressure. The selection of the anchor should be based on the temperature of its location and whether it is in direct contact with fuel gas.
The installation arrangement ways of the modules can be divided into parquet floor type and soldier row type. The parquet floor type is a traditional installation arrangement way and was very popular a few years ago. However, with the development of the development of the applied technology of ceramic fiber module, research and practice have proved that, the parquet floor type has some drawbacks. Therefore, it is only used in the bar pasted structure of the hot face. Currently, most programs adopt the soldier row type.
Monday, December 14, 2015
Melting methods of Fused Cast AZS Block
Fused cast AZS block is also called fusion cast AZS block and fused cast Al2O3-ZrO2-SiO2 block. AZS is the abbreviation of Al2O3, ZrO2 and SiO2.
Fused cast AZS block is composed of 50%-70% Al2O3, 20%-40% ZrO2 and a small amount of SiO2 and other components. Based on the ZrO2 content, it can be divided into AZS 33#, AZS36# and AZS 41#. The most commonly used is AZS 33#, which has a density of 3.1-3.4g/cm3 and maximum service temperature of 1700 degree.
Based on the position of the electrode, the melting methods of fused cast AZS can be classified into the reducing method and the oxidizing method. The electrode of the reducing method is inserted into the melt, while the electrode of the oxidizing method is over the liquid level.
Products made by different methods have different mineral composition as well as different proportions and different content of reducing substances (C, H) . All these will affect the exudation temperature exudation amount of glass phase.
Now most manufacturers adopt the oxidizing method, since it can reduce the carbon content to 0.003%-0.006% by long arc melting and blowing oxygen to the melt. Compared to the reducing method, it can produce fused cast AZS block with higher corrosion resistance to molten glass and higher exudation temperature.
Fused cast AZS block is composed of 50%-70% Al2O3, 20%-40% ZrO2 and a small amount of SiO2 and other components. Based on the ZrO2 content, it can be divided into AZS 33#, AZS36# and AZS 41#. The most commonly used is AZS 33#, which has a density of 3.1-3.4g/cm3 and maximum service temperature of 1700 degree.
Based on the position of the electrode, the melting methods of fused cast AZS can be classified into the reducing method and the oxidizing method. The electrode of the reducing method is inserted into the melt, while the electrode of the oxidizing method is over the liquid level.
Products made by different methods have different mineral composition as well as different proportions and different content of reducing substances (C, H) . All these will affect the exudation temperature exudation amount of glass phase.
Now most manufacturers adopt the oxidizing method, since it can reduce the carbon content to 0.003%-0.006% by long arc melting and blowing oxygen to the melt. Compared to the reducing method, it can produce fused cast AZS block with higher corrosion resistance to molten glass and higher exudation temperature.
Friday, December 11, 2015
Tuesday, December 8, 2015
Two Ways to Install the Ceramic Fiber Lining
There are three ways to install ceramic fiber lining: external thermal insulation, internal thermal insulation and intermediate thermal insulation. The intermediate thermal insulation, due to its drawbacks, is rarely used.
The ceramic fiber materials used to install the ceramic fiber linin include ceramic fiber board, ceramic fiber blanket and ceramic fiber module. The lining is generally 25-50mm, and 50-100mm is preferred.
1) External thermal insulation
The ceramic fiber board is pasted or anchored to the cold surface of the furnace walls. This structure simply needs low temperature fiber products or lightweight bricks.
2) Internal thermal insulation
Ceramic fiber board is pasted on the hot surface of the furnace walls. It has good thermal insulation performance in either batch or continuous furnaces. It can reduce the heat loss of the furnace wall and the regenerative loss.
3) Intermediate thermal insulation
The ceramic fiber layer is installed in the middle of the furnace wall.
The adhesives commonly used include agents made with Silica gel and water glass or mud formulated with Portland cement and sulphate.
Now most furnaces adopt the internal thermal insulation structure, since it has high thermal efficiency, good energy-saving effect and long service life. Of course, in some cases, the structure and construction method should be chosen based on the actual situation.
Zhengzhou sunrise refractory Co., Ltd. is a refractory supplier from China, specializing in various ceramic fiber materials for glass furnaces, such as ceramic fiber board, ceramic fiber blanket, ceramic fiber module, etc.
The ceramic fiber materials used to install the ceramic fiber linin include ceramic fiber board, ceramic fiber blanket and ceramic fiber module. The lining is generally 25-50mm, and 50-100mm is preferred.
1) External thermal insulation
The ceramic fiber board is pasted or anchored to the cold surface of the furnace walls. This structure simply needs low temperature fiber products or lightweight bricks.
2) Internal thermal insulation
Ceramic fiber board is pasted on the hot surface of the furnace walls. It has good thermal insulation performance in either batch or continuous furnaces. It can reduce the heat loss of the furnace wall and the regenerative loss.
3) Intermediate thermal insulation
The ceramic fiber layer is installed in the middle of the furnace wall.
The adhesives commonly used include agents made with Silica gel and water glass or mud formulated with Portland cement and sulphate.
Now most furnaces adopt the internal thermal insulation structure, since it has high thermal efficiency, good energy-saving effect and long service life. Of course, in some cases, the structure and construction method should be chosen based on the actual situation.
Zhengzhou sunrise refractory Co., Ltd. is a refractory supplier from China, specializing in various ceramic fiber materials for glass furnaces, such as ceramic fiber board, ceramic fiber blanket, ceramic fiber module, etc.
Thursday, December 3, 2015
What is Magnesium Silicate Insulation Board?
Magnesium Silicate Insulation Board is a new lightweight insulation material with low thermal conductivity, good insulation properties and heat resistance.
The Magnesium Silicate Insulation board is made of sepiolite matrix material (mainly magnesium silicate) by pulping, molding, forming and drying. Within the operating temperature range, it can be used for a long term without aging and deterioration. It is non-toxic and odorless.
The Magnesium Silicate Insulation board features with high structural strength, low deformation after sintering, fine heat-conducting property and damp-proof. Especially its physical performance is quite stable under high-temperature operation. The application of this board can promote the volume stability of the whole liner, reduce furnace surface temperature, eliminate operating force among bricks, so as to ensure furnace’s safety performance and effectively save the energy.
The shell temperature of test ladle that takes Magnesium Silicon Thermal Insulation Board as liner is much lower than that of common ladle, which averagely reduces 75℃, while the maximum temperature reduction will be about 120℃. Therefore, the board application will facilitate to eliminate the deformation of ladle shell materials, and greatly improve operation environment of ladle. The temperature drop rate of molten steel is smaller than that of common ladle, namely average 0.3~0.5℃/min. It indicates that the heat preservation of molten steel is quite great, which can not only save energy and heat losses, but also is beneficial for the constant temperature and rate during steel casting process to ensure the smooth continuous casting.
Magnesium Silicate Insulation Board is mainly used for metallurgy, building materials, furnace heat preservation, fireproof materials, etc. compared to other insulation materials, it is easy to install and cut and has no pollution to the environment, no irritation to skin and no loss during the construction.
The Magnesium Silicate Insulation board is made of sepiolite matrix material (mainly magnesium silicate) by pulping, molding, forming and drying. Within the operating temperature range, it can be used for a long term without aging and deterioration. It is non-toxic and odorless.
The Magnesium Silicate Insulation board features with high structural strength, low deformation after sintering, fine heat-conducting property and damp-proof. Especially its physical performance is quite stable under high-temperature operation. The application of this board can promote the volume stability of the whole liner, reduce furnace surface temperature, eliminate operating force among bricks, so as to ensure furnace’s safety performance and effectively save the energy.
The shell temperature of test ladle that takes Magnesium Silicon Thermal Insulation Board as liner is much lower than that of common ladle, which averagely reduces 75℃, while the maximum temperature reduction will be about 120℃. Therefore, the board application will facilitate to eliminate the deformation of ladle shell materials, and greatly improve operation environment of ladle. The temperature drop rate of molten steel is smaller than that of common ladle, namely average 0.3~0.5℃/min. It indicates that the heat preservation of molten steel is quite great, which can not only save energy and heat losses, but also is beneficial for the constant temperature and rate during steel casting process to ensure the smooth continuous casting.
Magnesium Silicate Insulation Board is mainly used for metallurgy, building materials, furnace heat preservation, fireproof materials, etc. compared to other insulation materials, it is easy to install and cut and has no pollution to the environment, no irritation to skin and no loss during the construction.
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