aluminabricks, Author at RS Kiln Refractory Bricks

Refractory spray paint is used to spray new linings and can also be used to repair furnace pipes. Spraying construction method of Rongsheng high-temp refractory coating. It is an effective unshaped refractory material that is easy to construct, extends the service life of the kiln, and reduces the consumption of refractory materials. The material composition of refractory spray paint is basically similar to that of refractory castables of the same type. The difference is that the critical particle size of refractory aggregate is smaller, generally 3~5mm, and is constructed using spraying methods. The dosage of refractory powder, ultrafine powder, and binder is relatively large, generally 35~45%.

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Spraying Process of Refractory Coating

Spraying is carried out using a spray machine or spray gun. The material obtains considerable speed with the help of compressed air and is sprayed onto the sprayed surface through the nozzle, forming a strong spray layer. The key technologies of refractory spray coatings are mainly adhesion, bonding, strength, and sintering. This is also the basic characteristic that the material should have, otherwise the service life of the spray coating will be reduced. These characteristics are not only related to the quality of the material itself, but also affected by the spraying equipment, construction technology, and the state of the sprayed body.

The particles of refractory spray paint cannot be larger than 5mm. Because when it is larger than 5mm, the spray gun will be blocked and normal construction will not be possible. During construction, the refractory spray coating is sprayed 40-50mm into the pipe, and the spray coating can be quickly formed. Generally speaking, the rebound rate of refractory spray coatings produced by refractory spray coating manufacturers is 10%.

In refractory spray coatings, medium and fine particles can greatly improve the adhesion rate, but will increase peeling during drying. Coarse particles can make the repair layer more stable, but too many coarse particles will lead to a high rebound rate and increase the amount of material used. Therefore, the particle gradation must be reasonable and cannot exceed 5mm. Because it exceeds 5mm, the spray gun cannot spray. Reasonable gradation can best improve the construction and use performance of spray coatings.

High-Temperature Refractory Coatings

Refractory spray coatings are divided into light spray coatings and heavy spray coatings. The materials selected according to different use environments include corundum, high alumina, mullite, clay, SiC, magnesium, etc. Mainly used in hot blast furnaces, heating furnaces soaking furnaces, blast furnaces, flues and chimneys, etc. However, lightweight refractory spray coatings are relatively more expensive than heavy refractory spray coatings.

The density of heavy refractory spray paint is generally 1.6-1.8g/cm3. However, there are different requirements in different furnace pipelines. Especially the sintering machine pipes must be made much better than other parts. In other words, this part needs to use refractory spray paint with a density of 2.2g/cm3. Of course, the price of refractory spray paint for sintering machines will be much higher than that of refractory spray paint for other parts.

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What is Refractory Coating?

(1) Heavy refractory spray paint

The bulk density of heavy refractory spray coatings is generally greater than 1.8g/cm3. Refractory aggregates and powders generally use aluminum silicate materials, with a critical particle size of 5 or 10 mm. Particle composition: 3~5mm is about 30%, 1~3mm is about 30%. Less than 1mm is about 40%. The binding agent is aluminate cement and water glass, plus additives. Generally, semi-dry method or false dry method is used for construction.

Main properties of heavy refractory castables. The medium temperature strength of CA-50 cement spray coating is reduced. However, water glass and phosphate spray coatings increase with the increase of heating temperature, and their bulk density is slightly lower than the same type of refractory castables produced by vibration molding.

In recent years, medium-heavy refractory spray coatings with a bulk density of 1.8~2.1g/cm3 have been developed. That is, on the basis of heavy materials, 3% to 6% expanded perlite or 5% to 20% porous light clinker is added. It is mainly used on the heat insulation layer of kilns and has good heat preservation effect.

(2)Lightweight refractory spray coating

There are many varieties of lightweight refractory spray coatings, mainly including clay, ceramsite, perlite and other refractory spray coatings. Lightweight refractory spray paint is mainly used for the thermal insulation layer of kilns, and can also be used for the working layer of tubular heating furnaces, flues and chimneys.

The critical particle size of refractory aggregate for lightweight refractory spray paint is 5mm. The particle gradation is: 3~5mm, about 19%~30%. 0.6~3mm is about 8%~14%. 0.088~0.60mm is about 30%~40%, and less than 0.088mm is about 25%~35%.

The main properties of lightweight refractory spray coatings. During the spraying construction process of refractory spray paint, the original particle gradation will be greatly changed due to the rebound and scattering of refractory aggregates and the splashing of refractory powder. Therefore, when the aggregate size requirements of the refractory spray coating are certain, in order to make the aggregate gradation of the actual spray coating meet the requirements, the original gradation before spraying must be adjusted to meet the requirements after spraying.

coating material — refractory spray coating

Spraying construction of Rongsheng Refractory Spray Coating

Before spraying paint, test spraying should be carried out in accordance with the construction instructions provided by the manufacturer for the brand of spray paint. To determine the appropriate parameters, such as wind pressure, water pressure, etc.

Several commonly used spray coatings

(1) When spraying clay materials at room temperature, the aggregate particle size should be below 3.5mm. When the spray paint lacks viscosity, 2% clay should be added to improve its construction performance.
(2) When spraying high-aluminum materials at room temperature, additives should be added to prevent falling and increase the density of reinforced metal parts.
(3) When lightweight insulation materials are used for spraying, lightweight aggregates with higher strength should be used, and appropriate amounts of asbestos and clay should be added. Aggregates with low strength, brittle under pressure and friction, or elastic aggregates are not suitable for spraying. The volume density of lightweight thermal insulation spray paint should be between 0.7~1.3t/m3.

Reinforcement metal parts

Spraying construction must be reinforced with metal supports. Metal supports should have the characteristics of simple shape, small size, and reliable performance. Generally, it should be made of round steel.

When the thickness of the spray coating is 35~75mm, metal mesh should be used for reinforcement. The diameter of the metal mesh is Φ3.2~4.2mm, and the mesh size should be 1.5 times the thickness of the spray coating. And it is fixed on the furnace wall by welding, binding, and crimping.

When the spray thickness is more than 100mm, round steel of 4~8mm should be used to make V-shaped or Y-shaped metal parts and welded to the furnace shell.

The installation distance of metal parts: the side wall part should be 3 times the thickness of the spray coating, and the top part should be 1.5~1.8 times the thickness of the spray coating. The distance from the front end of the metal anchor to the surface of the spray coating should be 50mm for the side wall and 25~30mm for the ceiling.

Process inspection before spraying

The following process inspections should be carried out before spraying refractory spray paint:

(1) Before spraying, the installation position, spacing size, and welding quality of the metal supports should be checked and cleaned.
(2) When there is a fixed steel wire mesh on the support frame, check whether the anchoring quality of the steel wire mesh meets the requirements. The upper, lower, left, and right sides of the steel wire should overlap one grid. The overlap shall not exceed three layers and the fasteners shall be oriented toward the non-working layer.
(3) Check the sprayed surface. There should be no floating rust, dust accumulation, oil stains, or water immersion on the sprayed surface.

Spraying operations and adjustments

Refractory spray paint is sprayed onto the sprayed surface with a spray gun. Materials constructed by spraying are called refractory spray paint. Spraying is carried out using spray machines and spray guns. The refractory spray paint uses compressed air or mechanical pressure in the pipeline to obtain sufficient pressure and flow rate. Spray onto the sprayed surface through the nozzle to form a solid spray layer.

The spraying methods of refractory spray coatings are divided into three categories: wet method, dry method, and flame method. When constructing refractory spray coatings, appropriate construction plans for high-temperature coatings and refractory coatings can be specified based on actual working conditions. To extend the service life of the kiln lining.

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Mar 8 2024

How to Choose Honeycomb Ceramic Regenerator?

In recent years, honeycomb regenerative furnaces have developed very rapidly. Since the regenerator can be miniaturized and integrated with the burner, and each burner maintains its independence, it becomes a regenerative burner. It truly achieves extreme waste heat recovery and ultra-low NOX emissions. The energy-saving effect brought by regenerative combustion technology is very obvious. It can absorb the heat of high-temperature flue gas to the maximum extent and avoid heat waste. Honeycomb ceramic regenerator is the key and core component of regenerative high-temperature combustion technology.

RS Honeycomb Ceramic Regenerator for Sale

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How to Choose the Honeycomb Ceramic Regenerator?

The selection of a honeycomb ceramic regenerator is very critical. Improper selection will cause blockage, burning, collapse, and other phenomena during use, causing the furnace temperature to rise slowly, failing to reach the temperature, and in serious cases causing furnace shutdown accidents. It affects production and increases gas consumption.

Therefore, when selecting a honeycomb body, in addition to considering the rapid cooling and rapid heating resistance of the honeycomb ceramic regenerator, load softening temperature, compressive strength, thermal expansion coefficient thermal shock resistance, and other indicators. The heat release characteristics of the honeycomb ceramic regenerator also need to be considered. It is necessary to select a honeycomb ceramic regenerator made of materials with a large specific surface area, large blackness, large heat capacity, and fast thermal conductivity. In this way, the honeycomb ceramic heat storage body absorbs and releases heat faster and more, and can effectively absorb the heat of the flue gas. Significantly increase the preheating temperature of gas and air, increase the combustion temperature of the heating furnace, and achieve the purpose of reducing gas consumption.

Silicon Carbide Honeycomb Ceramic Regenerator

The silicon carbide honeycomb ceramic regenerator is an improvement based on the formula of the corundum-mullite honeycomb ceramic regenerator. A certain amount of high-purity silicon carbide is added to improve the performance of the original honeycomb ceramic regenerator. Silicon carbide honeycomb ceramic regenerator combines the advantages of silicon carbide, zirconium chromium corundum, and other materials. It has the characteristics of good antioxidant, slag resistance, high-temperature resistance, high blackness, and fast thermal conductivity. Its high-temperature strength can be maintained up to 1600°C, making it the material with the best high-temperature strength among ceramic materials. Due to its fast thermal conductivity and high blackness, it has better energy-saving properties than a corundum-mullite honeycomb ceramic regenerator. According to relevant customer usage statistics, the use of silicon carbide honeycomb ceramic regenerators can significantly reduce the exhaust temperature of exhaust gas and reduce gas energy consumption by more than 5-10% compared with other honeycomb ceramic regenerators. Silicon carbide honeycomb ceramic regenerator is mainly used as the heat exchange medium for high-temperature regenerative industrial kilns above 1250°C.

Large Holes Honeycomb Ceramic Regenerator

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Large Holes and Big Eyes Honeycomb Ceramic Regenerator

The hole shapes of honeycomb ceramic regenerators often include square holes, round holes, hexagonal holes, etc., and the hole spacing is usually between 3-6mm. Among them, the hexagonal hole surface layout is more uniform and the structure is more stable. It is currently the most commonly used hole type. In addition to matching the medium pressure, flow rate, burner combustion capacity, and other factors, the selection of hole type and aperture should also pay attention to the actual medium quality conditions. For exhaust gas with high dust content, the hole diameter and wall thickness should be appropriately increased. Choose a honeycomb ceramic regenerator with large holes and large eyes to reduce the clogging and corrosion hazards caused to the honeycomb ceramic regenerator.

The honeycomb ceramic regenerator with large holes and large eyes is mainly used to deal with the harsh working environment of some industrial furnaces and the high dust content in the flue gas. During use, the small holes of the honeycomb ceramic regenerator often become blocked. After the small holes of the honeycomb ceramic regenerator are blocked, not only will its heat storage and smoke exhaust performance be significantly reduced. It also causes smoke exhaust and uneven heating of the honeycomb ceramic heat storage body, which is prone to cracks and aggravates its damage. In regenerative industrial furnaces with harsh working environments and high dust content in flue gas, the use of honeycomb ceramic regenerators with large holes and large eyes can effectively avoid clogging the small holes of conventional honeycomb ceramic regenerators.

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RTO Incinerator Honeycomb Ceramic Regenerator

The honeycomb ceramic regenerator of the RTO incinerator has the characteristics of high softening temperature under load, small expansion coefficient, strong resistance to rapid cooling and rapid heating, and long service life. The basic principle of an RTO incinerator is to oxidize organic waste gas at high temperatures (>760℃) to generate CO2 and H2O. The use of honeycomb ceramic regenerators can maximize the recovery and reuse of heat energy, with a heat recovery rate greater than 95%. The geometric characteristics of the RTO honeycomb ceramic regenerator are generally made into columnar regenerators with dimensions of 150mm×150mm×150mm and 150mm×150mm×300mm and are integrated into the RTO regenerator. The number of holes in the cross-section of a piece of packing that airflow passes through is called the hole density, also expressed by the number of holes per square inch (CSI). Usually from 13×13 (number of holes 169) to 60×60 (number of holes 3600).

The greater the hole density, the larger the surface area per unit volume, which can provide a larger heat transfer area and thereby improve the heat transfer efficiency. The organic waste gas is heated to above 760°C, causing the VOC in the waste gas to oxidize and decompose into carbon dioxide and water. The high-temperature gas generated by oxidation flows through the special ceramic heat storage body, causing the ceramic body to heat up and “storage heat”. This “heat storage” is used to preheat the subsequent incoming organic waste gas. This saves fuel consumption for exhaust gas heating.

The honeycomb ceramic regenerator of the RTO incinerator should be divided into two or more zones or chambers. Each regenerator goes through the procedures of “heat storage-heat release-cleaning” in turn, starting over and over again and working continuously. After the regenerator “releases heat”, part of the clean exhaust gas that has been processed should be introduced immediately, and the regenerator should be cleaned to ensure that the VOC removal rate is above 95%. Only after cleaning is completed can the “heat storage” program be entered.

Honeycomb Ceramic Regenerator from Rongsheng

Corundum Mullite Cordierite Honeycomb Ceramics

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Honeycomb ceramic regenerator is the key material of regenerative industrial kilns, and it is the heat exchange medium of regenerative industrial kilns. The honeycomb ceramic regenerator absorbs and stores the heat from the waste gas in the industrial kiln, and then uses the stored heat to heat the air and fuel. This not only increases the calorific value of the fuel, lowers the emission temperature of exhaust gas, and saves energy, but also reduces the emissions of CO2 and NOX, which is helpful for environmental protection. The cross-sectional holes of honeycomb ceramic regenerators mainly have square, regular hexagonal, and circular three-hole structures. Moreover, the pores are straight channel structures that are parallel to each other. This structure greatly reduces the resistance of the pores to flow through and greatly improves the single-hole volume heat transfer efficiency of the honeycomb ceramic regenerator. The main materials of the honeycomb ceramic regenerator of the RTO incinerator are dense cordierite, high alumina, corundum mullite, chromium corundum, zirconium corundum, silicon carbide, etc. Contact us for a free quote.

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Feb 2 2024

Corundum Castable that is Resistant to High Temperatures and Slag Erosion

Corundum castable is a high-grade castable in a series of unshaped refractory materials. It has a stable crystal structure has more stable performance in high-temperature sintering processes, and is suitable for use in high-temperature areas lined with various kilns. Corundum castable that is resistant to high temperatures and slag erosion. Refractory castables made of this material can better reflect its fire resistance and wear resistance at high temperatures. Its thermal shock resistance can also achieve better performance at high temperatures, and its performance is reliable and reliable during high-temperature operation of the kiln.

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High-Grade Corundum Castable

Corundum castable is used in high-temperature parts of industrial kilns between 1400℃ and 1650℃. It is produced using bauxite clinker and corundum with an aluminum content of more than 90% as aggregate, using micro-powder technology and pure calcium aluminate cement. This kind of corundum refractory castable has high strength, high volume density, and strong high-temperature stability. Used in high-temperature parts of industrial kiln linings, it has strong resistance to slag erosion, wear resistance, and high-temperature gas erosion resistance.

Performance Characteristics of Corundum Castables

Corundum castables have high-energy effects of high temperature resistance and corrosion resistance, and can still maintain stable performance under long-term use. It can be combined with silicon carbide, mullite, andalusite, sillimanite, etc. to make composite refractory castables. It can be used in high-temperature furnace lining parts in different atmospheres.

The high-temperature main crystal phase of corundum castable is corundum refractory castable. It is a refractory castable prepared with special high-alumina bauxite clinker or fused brown corundum as aggregate, adding refractory powder, pure calcium aluminate cement binder, silica powder, and admixtures. Usually, the pouring method is used for construction. It can be cast into a complete lining, or prefabricated blocks of castable materials customized by the manufacturer can be spliced on-site for use.

Corundum Castable Refracotry for the C F B Boiler — Corundum Castable Refractory of Slag Corrosion Resistance

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Product Features of Corundum Castables

(1) High compressive strength and strong lining stability at high temperatures.
(2) The volume density is high, and the overall lining has strong resistance to slag erosion and permeability.
(3) Strong resistance to erosion by solid particles, dust, and high-temperature gases.
(4) Low mechanical wear resistance.
(5) Not affected by reducing gases such as H2 and CO.

Corundum Castable Product Uses

The use temperature of corundum castable is 1600-1700℃, and it is mainly used as lining material for various high-temperature kilns and high-temperature structures. Such as the outer lining of the impregnation tube of the molten steel vacuum degassing device, the lining of the spray metallurgy, and the argon-blowing integral spray gun. The lining body of the electric furnace top triangular area and the LF furnace cover. High-temperature wear-resistant lining for catalytic cracking reactors in the petrochemical industry. High-temperature wear-resistant lining for circulating fluidized beds and power plant boilers.

How to Improve the High-Temperature Slag Corrosion Resistance of Corundum Castables?

The development trend of dense refractory castables requires the calcium aluminate cement content to be reduced as much as possible while maintaining good green strength and high-temperature mechanical properties. The key technology is to increase the packing density between particles. The above purpose can be effectively achieved by adding micron powder, submicron powder, or even nano-alumina powder. The reasons are:

1) Reduce the CaO content in the castable and reduce the low melting phase generated at high temperatures. It can significantly improve the high-temperature mechanical properties of castables.
2) Promote sintering at medium temperature and increase the medium temperature strength of castables.
3) Reduce the total amount of water added and increase the density of the castable.

Corundum Refractory Castable — Corundum Castable Refractory Lining Materials

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In terms of comprehensive cost performance, the role of alumina micropowder cannot be ignored. Its particle morphology, size, particle size distribution and specific surface area will have a great impact on the performance of the castable. In particular, the particle size distribution plays an important role in filling the pores between aggregates and increasing the packing density. Research has found that using composite micropowders with different particle size distributions can significantly increase the packing density. Reducing water consumption is beneficial to mechanical properties such as high-temperature flexural resistance and post-thermal shock strength. Li Wenping studied the influence of alumina powder particle size on the properties of castables. It was found that as the particle size of the micropowder decreases, the flowability and setting time of the castables both show an increasing trend.

More importantly, alumina micro-powder can promote the formation reaction of the CA6 phase of calcium aluminate cement at high temperatures, thereby significantly improving the high-temperature properties of castables. Pinto et al. found that the particle size of alumina powder decreased. It can nearly double the flexural strength of castables containing 1% (mass fraction) CAC cement and promote the formation of the CA6 phase. Auvray et al. discovered the optimization of alumina micro-powder and the in-situ generation of CA6. Ceramic bonding can be formed in the castable, which significantly improves the high-temperature elastic modulus of the castable. Specifically,

1) As the alumina fine powder content increases and the corundum fine powder content decreases, the normal temperature performance and high-temperature performance of the castable samples after heat treatment at different temperatures are improved to varying degrees. After being treated at 1600°C, the normal temperature flexural strength, normal temperature elastic modulus, and elastic modulus at 1400°C can be increased by 53.9%, 47.9%, and 40.4% respectively.
2) Adding too much micro powder is detrimental to the thermal shock stability of the castable. The more the amount of alumina powder is added, the residual flexural strength retention rate of the sample after thermal shock decreases with the increase in the amount of alumina powder. After three water-cooling thermal shocks, the residual flexural strength retention rate of the material decreased from 18.45% to 11.97%.
3) As the content of aluminum oxide powder increases, the slag erosion resistance of the castable gradually increases, and the thickness of the permeable layer decreases from 2.9mm to 2.1mm. The higher content of micro-powder will make the pore diameter of the castable smaller, promote the interpenetration and bonding of plate-like CA6 in the original layer, and make the matrix bonding closer. It is beneficial to improve the slag resistance performance of castables.

To purchase high-quality corundum castable refractory lining materials, please contact us.

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Copper Metallurgy Refractory Industrial Refractory

Jan 17 2024

Magnesium Chromium Refractory Bricks for Outokumpu Flash Smelting Furnace

As environmental protection becomes increasingly stringent, the copper metallurgical industry is facing severe challenges. Today, there are two main copper metallurgical methods: the fire method and the wet method. Among them, the fire method plays a major role, and the lining is mainly made of alkaline refractory bricks.

There are many types of pyrometallurgical furnaces. At present, the main pyrometallurgical copper smelting equipment in the world includes flash furnaces, reverberatory furnaces, blast furnaces, Noranda furnaces, and ISA furnaces (Osmet furnaces). There are more than ten kinds of smelting equipment such as Vanukov furnaces, Mitsubishi furnaces, Tenient furnaces, electric furnaces, silver furnaces, and so on. Most processes have problems such as low production capacity, high cost, high energy consumption, and serious pollution. Seriously restricting the development of the copper metallurgical industry.

Legend: Outokumpu flash smelting furnace

Outokumpu Flash Smelting Furnace

Since the advent of Outokumpu in Finland in 1949, flash smelting has gradually replaced the reverberatory furnace and blast furnace through continuous improvement, improvement, and development. Today it has become a competitive smelting technology used in today’s copper metallurgy and is generally considered the standard clean copper smelting process.

Currently, more than 50% of global blister copper production is produced using this technology. Due to the mature flash smelting process, it has a high degree of automation, large production capacity, low energy consumption, and good environmental protection. At present, most of the newly built or renovated and expanded copper smelting enterprises in the world adopt the flash smelting process.

Flash Furnace Structure

Outokumpu flash smelting uses oxygen-rich air or hot air at 723~1273K as the oxidizing gas. A down-spray concentrate nozzle is installed at the top of the reaction tower. The dry concentrate and flux are sprayed into the reaction tower at high speed with oxygen-rich air or hot air and are suspended in the tower. During the downward movement of the material, an oxidation reaction occurs with the oxygen in the airflow, releasing a large amount of heat. The temperature in the reaction tower is maintained above 1673K. The material reacts rapidly (2~3s) at high temperatures, and the resulting melt settles into the sedimentation tank. Complete the matte-making and slag-making reactions, and carry out clarification and separation.

Refractory Materials for Outokumpu Flash Smelting Furnace

Outokumpu flash smelting furnace consists of a reaction tower, sedimentation tank, and rising flue. The operating temperature in the tower is 1400~1500℃. Its work is subject to high temperatures, chemical erosion, and charge erosion, and is easily damaged. Generally, alkaline refractory bricks are used.

The top of the tower is suspended and built with fired magnesia-chromium hanging bricks, with a thickness of about 400mm. The lining around the spray nozzle and burner can be integrally rammed with magnesia-chromium refractory ramming material with a Cr2O3 content of 20%. First, install the finned cooling water pipe on the furnace shell. Lay a 20mm thick insulation board or refractory fiber felt, and then pound the magnesia-chromium refractory ramming material layer. Finally, the working layer is built with cast magnesia chromium bricks. The working layer of the tower wall 1m close to the top of the tower is allowed to be built with fired magnesia chrome bricks. The materials and structure used on the top of the sedimentation tank are the same as those on the top of the tower.

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Water-cooled copper sleeves are installed in the slag line area of the pool wall to protect the lining body and are all built with fused magnesia-chromium bricks, while the remaining pool walls are built with fired magnesia-chromium bricks. The total thickness of the anti-arch furnace bottom of the sedimentation tank is about 1800mm. First, 20mm thick asbestos boards or insulation boards are laid against the furnace shell, and 3 layers of clay insulation bricks and 1 layer of clay bricks are laid vertically. Then pound a layer of magnesia-chromium refractory ramming material about 100mm thick. Then use fired magnesia-chromium refractory bricks to build the working layer. The rising flue is on the other side of the sedimentation tank and consists of side walls, sloping end walls, sloping tops, and flat tops. It is mainly built with ordinary fired magnesia chromium bricks.

The lining at the lower part of the inclined end wall is easily corroded, and water-cooled copper sleeves need to be buried to increase the service life. The lining body where the sedimentation tank vault meets the reaction tower and rising flue. Steel beams are used to bear the load and water-cooled copper sleeves with fins are installed, and the working layer is integrally poured with magnesia-chromium refractory castables. Its service life is much longer than that of bricks.

Under normal operating conditions, the service life of the refractory brick lining of a flash smelting furnace is generally 3 to 10 years. During this period, 1 to 3 medium and minor repairs are required.

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Dec 14 2023

Heat Storage Area Per Unit Volume of Hot Blast Furnace Checker Bricks

Refractory material manufacturer’s explanation of the heat storage area per unit volume of hot blast furnace checker bricks. Modern blast furnaces use regenerative hot blast furnaces, which are huge blast furnace blast heating facilities built up of checkered bricks. As a carrier of high-temperature heat, the working principle of checker bricks is to first burn gas, use the generated high-temperature flue gas to heat the checker bricks in the regenerator, and then pass the cold air through the hot checker bricks to be heated. The hot blast furnace alternately performs combustion and air supply, so that the blast furnace continuously obtains warm air. Therefore, improving the heat transfer efficiency of hot blast furnaces is of great significance to increasing the air temperature.

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Heat Storage Area Per Unit Volume of Hot Blast Furnace Checker Bricks

To improve the heat transfer efficiency of the hot blast stove, the hot blast stove checker bricks must have excellent thermal properties. Using checker bricks in the design and increasing the thermal area of the checker bricks is an important technical measure to improve the heat transfer capacity. Comparison of the heat storage areas of several typical checker bricks below.

Traditional 7-hole lattice brick. The grid hole diameter is 43mm and the heat storage area is 38.1m2/m3.
7-hole grid bricks. The diameter of the grid holes is 30mm, and the heat storage area is 47.08m2/m3.
19-hole grid brick. The grid hole diameter is 30mm and the heat storage area is 48.6m2/m3.
31-hole grid brick. The diameter of the grid holes is 25mm, and the heat storage area is 58.1m2/m3.
37-hole grid brick. The diameter of the grid holes is 20mm, and the heat storage area is 68.7 m2/m3.

The practice has proved that under basically the same conditions, the air temperature of a large blast furnace can be increased by 38°C when using 19-hole bricks with a diameter of 30mm compared with traditional 7-hole bricks with a diameter of 43mm. Using 31-hole bricks with a diameter of 25mm in small and medium-sized blast furnaces can increase the air temperature by 19°C compared with 9-hole bricks.

RS Refractory Material Manufacturer is a powerful refractory material manufacturer. The quality of our refractory products is reliable and guaranteed. And our comprehensive customer service can also provide reliable quality assurance for our refractory products. The description of the heat storage area per unit volume of hot blast furnace checker bricks can better help companies purchase suitable regenerator checker bricks.

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Application and requirements of checker bricks in hot blast furnace regenerator

Choose the appropriate size and thickness of checker bricks. When choosing the shape of checker bricks and the type of checker bricks, the following conditions and requirements should be considered:

① The quality of refractory materials.
② The degree of gas cleaning.
③ Different temperature conditions between the upper and lower parts of the hot blast furnace checker bricks.
④ It has high heat transfer efficiency and can increase the hot air temperature in a guaranteed amount.

Selection of checkered bricks for hot blast furnace regenerator

The regenerator of the hot blast stove is a space filled with checker bricks. Its main function is to use the internal checker bricks to exchange heat with high-temperature flue gas and combustion air. Therefore, as a heat storage and heat transfer medium, checker bricks should have a large heating area, high thermal conductivity, and quality to facilitate heat exchange and heat storage.

The main method to increase the heating area is to increase the number of holes in the checker bricks per unit area, so the number of holes in the checker bricks in the regenerator tends to increase. To improve the thermal conductivity of the material, black silica bricks are commonly used in Europe as checker bricks inside the regenerator. Because the iron oxide content in black silica bricks is high, it has high density, high thermal conductivity, strong heat storage capacity, and high heat exchange efficiency. Therefore, the upper part of the regenerator is made of siliceous check bricks, the middle part of the regenerator is made of low-creep high alumina bricks, mullite bricks, sillimanite, andalusite bricks, etc., and the lower part of the regenerator is generally made of clay bricks.

Modern regenerative hot blast stoves can basically be divided into two major types. The hood-type check bricks have a constant cross-section throughout the entire height, and the multi-section check bricks have varying cross-sections. The latter can be divided into three types, namely checkered bricks with alternating cross-sections, core-filled bricks, and brick wall surfaces with different roughness. Checkered bricks are available in a variety of shapes, such as square, rectangular, round, hexagonal, etc.

Rongsheng Checker Bricks for Glass Kilns — Rongsheng Checker Bricks

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1) Multi-section checkered bricks. It was more commonly used in the past. The checkered bricks of hot air stoves are also of this type. The points of multi-section grid bricks are as follows.

(1) When the quality of the refractory material is poor, the upper checker bricks are easily damaged due to high temperature. This difficulty can be overcome by increasing the diameter and thickness of the upper checker bricks. Increasing the checker brick diameter reduces heat transfer and therefore prevents the upper checker bricks from overheating. Increasing the thickness of the checker bricks can reduce the average temperature of the checker bricks so that the load softening point of the refractory bricks is not exceeded, which prevents the checker bricks from softening and deforming. To protect the checker bricks from having sufficient compressive strength, the thickness of the upper checker bricks should generally not be less than 50~60 mm.

By taking the above two measures, the wind temperature will not drop too much. Weakening the heat transfer effect of the upper checker bricks also means slowing down the cooling of the upper checker bricks themselves. Therefore, towards the end of the air supply stage, the outlet hot air temperature drops less. Additionally, thin bricks heat up quickly and cool down quickly. Therefore, increasing the thickness of the upper checker bricks can reduce the fluctuations in the temperature of the checker bricks themselves and the blast temperature.

(2) The temperature of the lower checkered bricks is low, the convective heat transfer effect is weakened, and the radiation heat transfer effect is also very small. Therefore, reducing the diameter of the lower checker bricks increases the airflow velocity accordingly, which can significantly improve the lower convection heat transfer effect. In addition, corrugated checker bricks and checker brick cores can also be used in the lower part. This not only increases the heating surface and reduces the diameter of the checker bricks, but also promotes turbulence in the airflow, which is conducive to convective heat transfer.

The lower checkered bricks should not be too thick. Because in the continuous alternation between the air supply period and the heating period of the hot blast stove, the temperature of the center of the lower checker brick rarely fluctuates and does not play a heat storage role. At the same time, thinning the lower checker bricks can also increase the heating area of the lower checker bricks. Therefore, the brick thickness of the lower checkered bricks is generally only 25~40 mm.

Generally speaking, when using ordinary clay bricks, multi-section checker bricks are in line with the temperature conditions and heat transfer laws in the furnace. And it can make the blast temperature drop less. However, it makes the cleaning operation of checkered bricks very difficult and prone to clogging.

2) Covered segmented checkered bricks. Recently, due to the continuous improvement of the quality of refractory materials and to avoid the difficulty of dust-cleaning operations, more and more cover-type checker bricks have been used. Although it does not comply with the rules of heat transfer, due to the use of high refractory materials, the entire checker brick can be made of smaller checker bricks and thinner brick thicknesses, which can also increase the heat transfer coefficient to make up for the shortcomings.

With the improvement of gas depressurization work, the checker bricks can be gradually reduced. At present, China generally uses 80×80 mm checkered bricks. To ensure sufficient mechanical strength, the thickness of checker bricks should not be less than 50 to 60 mm.

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Construction of Checkered Bricks for Hot Blast Furnace

Before laying checkered bricks in a hot blast stove, the grates and supports must be inspected. When inspected by the wire drawing method, the surface flatness deviation of the upper surface of the grate should be 0~5mm. The allowable deviation between the center line of the grate grid holes and the designed position should be 0~3mm.

The shape and size deviation of checker bricks should be accepted according to the relevant provisions of the current industry standard “High Alumina Bricks for Hot Blast Stoves” YB/T5016. Before construction, the usage plan should be determined based on the random inspection records of the dimensions of the checker bricks. Porous lattice bricks with tongues on the upper and lower sides should be layered according to height.

The grid hole at the center point of the regenerator should be used as the benchmark for determining the horizontal cross-center line control line of the brick grid on each layer. Each layer of grid bricks should be laid according to this horizontal cross-center line, and the grid holes should be kept vertical. During brick grid construction, wooden scales can be used to control the brick grid at the same time. During construction, a central control line should be established inside the surrounding furnace walls. The misalignment between the upper and lower brick grids should not exceed 5mm.

The surface of the brick grid should be smooth. The displacement of the brick grid holes to the furnace grate grid holes should not exceed 10mm, the complete number of grid holes should be counted and concealed engineering records should be filled in.

Expansion joints should be left between the surrounding checkered bricks and the furnace wall according to design regulations and should be fixed with wooden wedges.

Anti-scaling measures should be taken during construction and the grid holes must not be blocked. After the brick lattice is laid, it should be cleaned and the lattice holes should be inspected. If the bright light of the electric lamp can pass through the grid hole, or if the inspection steel drill lowered from above with a rope can pass through the full height of the grid hole, the grid hole should be considered qualified. The number of blocked holes should not exceed 3% of the number of complete holes in the layer brick grid. When using porous lattice bricks with upper and lower groove tongues for construction, the hole-blocking rate of the brick lattice does not need to be an inspection item.

When the brick lattice uses porous lattice bricks with groove tongues on the upper and lower floors, the upper and lower floors should be built with staggered joints and expansion joints should be left between bricks according to design regulations. The surrounding checkered bricks should be pre-processed and the arrangement diagram should be drawn in sequence.

To purchase hot blast stove regenerator checker bricks, heat storage hole bricks, and high thermal conductivity bricks, please contact us. We can provide high-quality refractory lining material products for high-temperature industrial furnaces. Our perfect customer service can provide long-life refractory materials for your high-temperature industrial furnace linings to save production costs.

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Nov 21 2023

Multifunctional Ceramic Fiber Refractory Material

Stability and safety in high-temperature environments are critical to many industries. To protect equipment and personnel, fire-resistant and fireproof materials play an important role. Among them, ceramic fiber, as a multi-functional fire-resistant, and fire-proof material, has the potential to be widely used. RS refractory material manufacturer can provide ceramic fiber material products for the insulation layer of high-temperature industrial equipment, including ceramic fiber blankets, ceramic fiber wool, ceramic fiber boards, etc.

Ceramic Fiber Blanket for High-Temperature Kiln

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Definition of Ceramic Fiber and Finished Product Types

Ceramic fiber is a refractory material in the form of long fibers made of inorganic materials. According to different production processes and material compositions, ceramic fibers can be divided into the following types of finished products.

Ceramic fiber felt: Ceramic fiber felt is a soft material made of ceramic fibers through spinning and other processes. It has excellent thermal insulation and sound absorption properties and is widely used in construction, aerospace, home appliances, and other fields.

Ceramic fiber yarn: Ceramic fiber yarn is made from ceramic fiber through a spinning process. It has high-temperature resistance and electrical insulation properties and is commonly used as insulation material in the fields of electronics, power, and aviation.

Ceramic fiber rope: Ceramic fiber rope is a rope-like product made of high-temperature refractory materials. Mainly made of ceramic fiber and organic fiber. Mainly used for sealing and filling industrial equipment, pipes, and furnaces.

Ceramic fiber board: Ceramic fiber board is a hard board made of ceramic fibers through pressing and sintering processes. It has high mechanical strength and earthquake resistance and is widely used in high-temperature insulation equipment and hearthstone structures.

Ceramic fiber paper: Ceramic fiber paper is a thin sheet material made of ceramic fibers through a wet papermaking process. It has excellent flexibility and corrosion resistance and is widely used in chemical industry, metallurgy, shipbuilding, and other fields.

Special-shaped ceramic fiber: Special-shaped ceramic fiber refers to products in which ceramic fibers are made into different shapes through special processing methods. Compared with traditional fiber boards or fiber blankets, ceramic fiber special-shaped shapes are more flexible and moldable and can be made into various complex shapes and sizes according to actual needs.

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Advantages of Ceramic Fiber

As a fire-resistant and fireproof material, ceramic fiber has many unique advantages.

High-temperature resistance. Ceramic fiber can maintain stability at extremely high temperatures, resist damage to materials caused by high-temperature environments, and protect the safety of equipment and personnel.

Excellent thermal insulation properties. Ceramic fiber has low thermal conductivity and high thermal insulation performance, which can effectively reduce heat transfer and provide good thermal insulation protection.

Corrosion resistance. Ceramic fiber has good corrosion resistance to corrosive media such as acids and alkalis, extending its service life.

Lightweight and flexible. Compared with metal materials, ceramic fibers are lighter and more flexible, easier to process and install, and reduce the conclusion part. Next is the application of ceramic fibers on different occasions.

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Application of Ceramic Fiber on Different Occasions

Due to their superior properties, ceramic fibers play an important role in many different fields.

Metallurgical industry. Ceramic fiber boards are widely used in high-temperature kilns and furnace structures in the metallurgical industry to provide effective thermal insulation protection.

Aerospace. Ceramic fiber yarn is used as electrical insulation material in the aerospace field for the insulation protection of circuit boards, cables, and sensors.

Chemical Industry. Ceramic fiber paper is often used as a lining material for acid and alkali containers in chemical plants to provide corrosion resistance and high-temperature resistance protection.

Power Industry. Ceramic fiber yarns and plates play an important role in power equipment and are used in electrical insulation materials and high-temperature insulation equipment.

Car manufacturer. Ceramic fiber felt is widely used in automobile exhaust systems to reduce heat transfer, improve engine efficiency, and reduce chassis temperature.

Fire protection field. As a fire-resistant and fire-proof material, ceramic fiber is widely used in firewalls, fire doors, and fire-proof clothing of buildings to provide reliable fire protection.

Ceramic Fiber Refractory Materials

As a multifunctional fire-resistant and fireproof material, ceramic fiber plays an important role in various fields. Different types of ceramic fiber finished products, such as yarn, felt, board, and paper, have the advantages of high-temperature resistance, excellent thermal insulation properties, corrosion resistance, and being lightweight and flexible. They are widely used in metallurgy, aerospace, chemical industry, electric power, automobile manufacturing, and fire protection fields. By providing effective thermal insulation protection, corrosion resistance, and fire protection, ceramic fiber materials provide a reliable solution for stability and safety in high-temperature environments. In the future, with the further development of technology, ceramic fiber materials will continue to play an important role in various fields, bringing greater convenience and safety to different industries.

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Oct 31 2023

What are the Reasons Why Refractory Bricks Can Resist High Temperatures?

Refractory bricks are inorganic non-metallic materials with a refractory degree of not less than 1580°C. It is a basic material for high-temperature technology, a structural material for masonry kilns and other equipment, and a functional material for manufacturing certain high-temperature containers and components or their special functions. The successful use of refractory bricks under high temperatures must have a good organizational structure, thermal properties, mechanical properties, and usability. That is to say, it has high refractoriness, load softening temperature, thermal shock resistance, and chemical erosion resistance so that it can withstand various powerful chemical changes and other effects, and meet the use requirements of thermal equipment and components. So, why can refractory bricks withstand high temperatures? RS Refractory Materials Manufacturer, a powerful refractory brick manufacturer, ensures that the refractory bricks can withstand high temperatures based on the raw materials of the refractory bricks and the characteristics of the molding and sintering process of the refractory bricks as inorganic non-metallic materials.

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Raw materials for refractory bricks

The raw materials used in the production of refractory bricks are generally natural ores. Refractory bricks with different properties are made by processing raw materials such as bauxite, silica, and magnesite. Such as aluminum-silicon refractory bricks, siliceous refractory bricks, and magnesia refractory bricks.

Aluminum-silicon refractory bricks are produced using bauxite as raw material. Its main component is alumina. Hydrated alumina containing impurities is an earthy mineral that is insoluble in water and soluble in sulfuric acid and sodium hydroxide solutions. It is mainly used for smelting aluminum and making refractory materials. Because the refractoriness of high-alumina clinker is as high as 1780°C, it has strong chemical stability and good physical properties. The bauxite is purified at high temperature to produce a corundum main crystal phase with an alumina content greater than 90%, which can produce ultra-high temperature refractory bricks – fused zirconium corundum bricks.

The raw material of silica refractory bricks is silica, and its main component is SiO2. The higher the content, the higher the refractory degree. The most harmful impurities are Al2O3, K2O, Na2O, etc. Silica bricks are made from natural silica as raw material, plus an appropriate amount of mineralizing agent to promote the conversion of quartz in the body into tridymite. It is slowly fired at 1350-1430°C in a reducing atmosphere. It has high-temperature strength and the load softening temperature is 1620℃.

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Magnesite is the main raw material for making magnesite refractory bricks. Its basic component is MgO. Magnesium oxide has high refractory insulation properties. It can be transformed into crystals after being burned at high temperatures above 1000°C and becomes sintered magnesia when the temperature rises to 1500-2000°C. Then it can be made into magnesia bricks or magnesia ramming materials after being crushed to a certain particle size or powder. Magnesia refractory bricks are alkaline refractory bricks, which have strong energy resistance to alkaline slag but cannot resist the erosion of acidic slag. The refractoriness is above 2000℃, but its load softening point is only 1500℃, and its thermal shock stability is poor.

Refractory bricks are inorganic non-metallic materials

Inorganic non-metallic materials, organic polymer materials, and metallic materials are listed as the three major materials. Common inorganic non-metallic materials are characterized by high compressive strength, hardness, high-temperature resistance, and corrosion resistance. In addition, ceramics have excellent corrosion resistance, and refractory materials have excellent properties in heat protection and insulation. These are incomparable to metal materials and polymer materials. However, compared with metal materials, it has low breaking strength and lacks ductility. Compared with polymer materials, they have higher density and complex manufacturing processes.

Forming and sintering of refractory bricks

The production process of refractory bricks is through mineral crushing-raw material mixing-mechanical molding-high temperature firing. This process finally produces a product that can withstand high temperatures. The sintering temperature of the green body passing through the high-temperature tunnel kiln will be higher than the load-softening temperature of the product. Generally, the sintering temperature is above 1500℃, the refractoriness is above 1770℃, and the high-temperature resistance is good. Refractory bricks are mainly used to build kiln linings such as steelmaking electric furnaces, glass furnaces, and cement rotary furnaces.

To summarize, there are three main reasons why refractory bricks can resist high temperatures. ① The raw minerals used in refractory bricks have high refractoriness. ② As an inorganic non-metallic material, the level of its use is determined by the level of raw materials. ③ The finished body has passed through a high temperature of over 1500°C in a high-temperature tunnel kiln, so the refractory bricks can resist high temperatures and are suitable for use in high-temperature kiln linings.

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Performance advantages of low porosity refractory bricks

Clay refractory products are extremely versatile and are made of high-quality raw materials. It is an indispensable refractory material for various industrial kilns. Low-porosity clay bricks were originally designed and widely used in hot blast stoves and glass kiln regenerators. Nowadays, it is widely used in lime kilns due to its good density and good resistance to chemical corrosion, especially alkali corrosion.

Low-porosity clay bricks are refractory products made from high-quality burnt gemstones as the main raw material, and their performance has been fully upgraded. The performance advantages of low porosity refractory bricks include.

Strong corrosion resistance.
Low porosity and high density.
High mechanical strength.
Strong anti-penetration ability.
High strength and high fire resistance.
The organization is dense.
Good thermal shock stability and resistance to peeling.

RS refractory brick manufacturer

RS Refractory Brick Manufacturer is a powerful manufacturer of refractory brick production and sales. Our refractory brick products have an annual output of 60,000 tons, and the quality is reliable and guaranteed. We have also made certain breakthroughs in thermal insulation material products. It has contributed a small step forward for energy-saving and heat preservation of high-temperature industrial furnaces. Our RS company can provide comprehensive refractory services for high-temperature industrial furnaces. Our professional technical team can also provide suitable solutions for the lining of high-temperature industrial furnaces. Material design and construction of refractory linings, and turnkey refractory projects. Contact us to get a free quote and samples.

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Oct 8 2023

Construction and Repair of Regenerator Checker Bricks

With the advancement of the times, reducing consumption and improving production efficiency have always been the primary goals of major enterprises. In the field of high-temperature industry, regenerative industrial grid bricks are widely recognized and accepted as a heat-carrying and heat-storage body with many superior thermal properties such as strong heat exchange capacity, large heat storage area, smooth ventilation, and low resistance. Checker bricks are a heat transfer medium used in blast furnaces hot blast furnace regenerators, coke oven regenerators, glass kiln regenerators, etc. Checker bricks are usually arranged in an orderly manner in the regenerator. It plays the role of heat storage during the “burning period”. During the “air supply period”, the cold air is heated into hot air through convective heat exchange and radiation heat exchange.

Basic characteristics of regenerator checker bricks

It has a plurality of transparent holes parallel to the side surfaces, as well as positioning protrusions and positioning grooves located on the two parallel surfaces.
Good volume stability, excellent creep performance under high-temperature load, high density, and low porosity. Modern blast furnace hot blast stoves usually adopt a checkered brick regenerator structure.

Checker Bricks for Blast Furnace — Construction of Checker Bricks in Hot Blast Stove

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Construction of Checker Bricks in Hot Blast Stove Regenerator

(1) The regenerator checker bricks usually use seven-hole checker bricks. During masonry construction, each layer should be arranged in a staggered manner, and the upper and lower grid holes should be aligned.

(2) The checkered bricks around the edges of the masonry and at the joints of the walls should be pre-processed according to the designed dimensions before masonry. During construction, the processed checker bricks will be laid in sequence according to the construction drawings. Be careful not to process checker bricks in the furnace. When building the wall of an internal combustion hot blast furnace with the furnace shell as the guiding surface, checker bricks can be processed appropriately in the furnace while taking protective measures.

(3) Before laying checkered bricks, the cross center lines should be drawn at the four angular directions of 0°, 90°, 180° and 270° of the wall masonry. Then pull out two rows of masonry center lines on both sides of the 90° and 270° lines, with the center column being the first row of masonry center lines.

(4) The checkered bricks on the first floor should be dry laid and laid in advance. The bricks can be laid formally after the center grid position is verified to be accurate and qualified. After the masonry is completed and it is confirmed that the surface flatness of the masonry meets the requirements, the second layer of checkered bricks will be laid.

(5) Each layer of checkered bricks is controlled according to the three rows of masonry center lines pulled out from the fence. Starting from the center line of each layer of checker bricks, lay the cross row of center bricks first. Then build the bricks along the four angles in the direction of the furnace wall.

(6) Allowable deviation of expansion joints between adjacent checker bricks

1) Clay checker brick: 4mm;
2) High alumina checker brick: 8mm;
3) Silica checker brick: 12mm.

Use yellow cardboard or foam plastic board to fill the expansion joint tightly. Before filling, process the board according to the reserved size and thickness of the expansion joint. Then when the checker bricks are being laid, the expansion joint plates are tightly attached to the sides of the checker bricks. Carry out simultaneously, build, and paste at the same time.

(7) After the first layer of checker bricks is completed, the processed checker bricks at the edge positions are laid in sequence. And check to confirm compliance.

(8) The expansion joint between the checker bricks and the furnace wall should be reserved according to the design and construction requirements. Use wooden wedges to wedge the expansion joint tightly.

(9) After the checker bricks are laid, clean the construction area. Check the hole position and smoothness of the grid holes again. If the electric light can pass through the grid hole or the inspection tool passes through the full height of the grid hole, the grid hole will be regarded as qualified.

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Coke Oven Regenerator Checker Brick Construction Process

After the furnace body is completed, blow air to clean the secondary grooves on the roof of the regenerator. Mark the control line between the central partition wall and the sealing wall on the regenerator wall.
Blow the checker bricks clean with compressed air and start preparing to lay the checker bricks.
When the first layer of checker bricks is dry-layed, check the location and stability of the checker bricks before dry-laying the lower layer of checker bricks.
The checkered bricklayer after the second layer should be stepped back from the central partition wall to the furnace head.
Always check whether the holes of each layer of checker bricks are unobstructed, and the upper and lower checkerboard bricks should be aligned.
Yellow cardboard can be used to maintain the width and stability of the gap between the grid bricks and the regenerator wall and non-flammable materials must not be used for the padding.
After the dry-laying of checker bricks in each regenerator is completed and the inspection is qualified, the construction of the regenerator sealing wall begins.
The regenerator walls and checker bricks of divided regenerator coke ovens should be constructed alternately in sections. Before each section of checkered bricks is dry-layed, the section should be sealed or partitioned, and the wall grooves should be cleaned. During the dry-laying process of checker bricks, pay attention to prevent refractory mortar from falling into the lower checker bricks. Once the dry-laying is completed and inspected to be qualified, immediately cover it with a protective board. The protective board should be set firmly and tightly, close to the wall of the regenerator to prevent refractory mud from leaking into the checker bricks.

Hot Repair Method of Checker Bricks for Glass Kiln Regenerator

After long-term high-temperature operation of the glass melting furnace, the refractory brick for the glass kiln lining and various equipment used have aged to varying degrees. In particular, the checker bricks in the regenerator were seriously damaged and blocked, seriously affecting the atmosphere in the glass-melting furnace. This situation not only increases energy consumption but also causes a large number of quality problems in the glass products produced. Therefore hot repair of checkered bricks is by far the most effective way.

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Thermal repair process of checker bricks in the regenerator

Hot repair preparation

Before hot repair, a specific hot repair plan must be developed. Equipment, tools, and checkerboard tiles should be ready for use. During hot repair, the ratio of raw and clinker should be adjusted, the pulling amount and pressure in the kiln should be controlled, and the temperature should be controlled to ensure the normal production needs of the furnace.

Replacement of checker bricks

After opening the regenerator, first clean out the old checkered bricks that have worn out inside. Special attention should be paid when dismantling old checker bricks, as the heat storage gradually decreases and the working conditions in the kiln change. The fire exchange should be manually controlled according to the situation and adjusted in time to ensure the hot spot temperature and melting.

Laying out new checkered tiles. The material of the regenerator grid bricks is the same as the original regenerator grid structure. It mainly uses three types: clay bricks, magnesia chrome bricks, and high-purity magnesia bricks. Layer clay bricks, magnesia chrome bricks, and high-purity magnesia bricks from bottom to top. Seal the thermal chamber door and withdraw the water tank. Seal the water tank door.

After the checker bricks in the regenerator are replaced and the door is sealed, it is very important to perform reasonable heating operations and monitor the temperature in the regenerator. During the entire heating process, the principle of “slow heating and no cooling” should be followed.

The effect of thermal repair of checkered bricks in regenerator

After the hot repair of checker bricks in the regenerator, the heat in the regenerator will be stable and the heat energy consumption will be reduced. Glass defects and frying time caused by material problems have been greatly reduced, and fuel consumption has been reduced.

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Aug 30 2023

Chemical Composition of Silicon-Aluminum Refractory Bricks

Aluminate-silicate refractory products are refractory products whose basic chemical composition is alumina and silica. According to the content of alumina, can be divided into three types: clay, high alumina, and semi-silicon. In addition to the main components, silicon-aluminum refractory bricks products also contain impurities such as Fe2O3, TiO2, CaO, Na2O, and K2O. The presence of these impurities will greatly reduce the refractoriness of the product. Rongsheng refractory manufacturers have rich experience in production and sales and will show you the chemical composition of silicon-aluminum refractory bricks.

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Chemical Composition of Silicon-Aluminum Refractory Bricks

Chemical composition is the basis of refractory materials, and the chemical composition of refractory materials is usually divided into two parts according to the content and function of each component. That is, the main component accounts for the absolute majority, and the secondary component accounts for a small amount. Subcomponents are the accompanying inclusions in raw materials and special additives (additions) in process manufacturing.

(1) Principal components. The main component is the component that constitutes the main body of the refractory and is also the basis for determining the characteristics of the product. If you know the main components in the chemical composition, it is easy to know the refractory body.

In addition to the main component of the refractory material made of special raw materials is close to 100%, the silicon-aluminum refractory material made of natural raw materials will inevitably be mixed with a certain number of inclusions. Therefore, the minimum value of the main component is stipulated in the quality regulations of refractory materials.

Even if the composition of the material is above the specified value, the type and quantity of the impurity components and the structure of the product still greatly affect the performance of the refractory brick. For example, when the impurity aluminum content in the production of silica bricks exceeds 1%, although the main component content (SiO2) is above the specified value, the performance of the product will still deteriorate. Therefore, the main component of refractory bricks is only one of the measures to ensure the quality of products, and this alone is not enough.

(2) Subcomponents. In addition to the main components, silicon-aluminum refractory bricks products usually contain a small amount of impurity components. In recent years, with the continuous development of industrial production, the requirements for the use of refractory materials are getting higher and higher. Therefore, the restrictions on the impurity components in the products are becoming more and more strict.

Rongsheng Silica Bricks for Sale — Silica Bricks

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Most of the impurity components in the material act as flux at high temperatures, which seriously reduces the refractory performance of refractory bricks. It is therefore generally considered a hazardous ingredient. Therefore, it should be avoided to exceed the specified limit in actual production. As for the mechanism of the flux effect on the impurity components in the material, there are two views.

1) A low-melting liquid phase is generated due to a chemical reaction.

2) Although the product is not necessarily low-melting, it generates a more liquid phase at the same temperature.

The research on the impact of impurity oxides in the Al2O3-SiO2 (silicon aluminum) system shows that R2O is the most harmful in the impurity components. Even if its amount is very low (<1%), it can make the product form a eutectic liquid phase at about 1000 ° C, which obviously reduces the fire resistance and high-temperature structural strength of the product. Alkali-containing slag or alkali-containing gas has a serious corrosion effect on silicon-aluminum refractory bricks products during use.

The lower the temperature at which the molten liquid phase is formed, the more liquid phase is formed. As the temperature rises, the faster the growth rate, the stronger the flux effect of the impurity components. Therefore, the impact on the fire resistance of the product is also greater.

In addition to the above, the role of impurities in refractory bricks (raw materials) also has the effect of reducing the firing temperature of products (raw materials) and promoting the sintering of products (raw materials). However, it should be noted that some properties of the product will also be reduced at the same time.

In the manufacturing process of silicon-aluminum refractory bricks, in order to promote the high-temperature change of the material and reduce the sintering temperature, sometimes a small amount of additives (additions) are added. According to its purpose and function, it can be divided into: 1) mineralizer; 2) stabilizer; 3) sintering agent, etc. These ingredients are also included in the chemical composition of the product.

When analyzing the chemical composition, the content of ignition loss, A12O3, SiO2, Fe2O3, TiO2, CaO, MgO, K2O, Na2O, etc. are generally mainly analyzed. Special products and raw materials are analyzed on request. The burning loss of refractory raw materials indicates the amount of degassed products (such as CO2) and organic substances that are thermally decomposed in the raw materials. Therefore, it can be judged that the volume shrinkage of the raw material during the heating process determines whether pre-burning is required in production to ensure that the volume of the product is stable.

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Aluminum Silicon Refractory Brick

Aluminum-silicon refractory bricks are refractory products containing Al2O3 and SiO2 and are a series of aluminum-silicon refractory bricks. Aluminum-silicon refractory bricks have a wide range of applications and occupy a very important position in the refractory application industry. Its consumption accounts for more than 40% of the total refractory products. From a definition point of view, aluminum silicon refractory bricks are a series, which includes multiple types of refractory bricks. RS Alumina Bricks is a manufacturer that can provide a variety of high-quality silica-alumina refractory bricks.

Aluminum-silicon refractory bricks are classified according to the order of increasing composition from SiO2 content to Al2O3 content:

(1) Silica brick: SiO2 content ≥ 93%;

(2) Semi-silica brick: Al2O3 content is 15%-30%;

(3) Clay brick: Al2O3 content is 30%-48%;

(4) High alumina brick: Al2O3 content ≥ 48%;

(5) Mullite bricks: Al2O3 content ≥ 72%, SiO2 content ≥ 28%;

(6) Corundum brick: Al2O3 content ≥ 90%.

It can be seen from the classification that silica bricks, clay bricks, and high alumina bricks are commonly used refractory bricks for kilns, and are often used for masonry kiln working layers and permanent layers.

To purchase high-quality silicon-aluminum refractory bricks products, please choose a strong refractory brick manufacturer. Rongsheng Refractory Material Manufacturer is a refractory material manufacturer with rich experience in production and sales. Our refractory brick products are reliable in quality, and at the same time, we also provide comprehensive design and solutions for refractory lining materials. Customize refractory materials according to different production needs. Contact us for free samples and quotes.

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Jun 24 2023

Moisture Retention and High Temperature Performance of Refractory Plastic

Refractory plastics are mainly used in heating furnaces, electric furnace tops, and other parts. Due to the shortcomings of short storage time and poor fire resistance, its application range is limited. However, this refractory material has some irreplaceable advantages, such as the high-temperature strength of the furnace body that can be constructed with plastic refractory materials, excellent thermal shock performance, low thermal conductivity, and flexible construction methods. Rongsheng refractory material manufacturer, based on years of production and sales experience, conducted some experimental analysis on the moisture retention performance and high-temperature performance of refractory plastics.

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Moisture retention and high-temperature performance of refractory plastic

(1) The use of super-grade downdraft kiln high-alumina bauxite as the main raw material can significantly improve the moisture retention performance of the refractory plastic.
(2) Using phosphoric acid and sulfuric acid in the form of a compound combination, and then adding an appropriate amount of admixture, it is possible to produce a refractory plastic with excellent moisture retention performance and strength indicators. Using a single combination method, the effect is not ideal enough.
(3) Select super-grade high-bauxite with dense sintering and low impurity content, minimize the content of iron oxide in the material, and add an appropriate amount of humectant, which can significantly extend the moisture retention period of the plastic refractory.

Selection of Refractory Plastic Aggregate

The new type of plastic refractory should have excellent plasticity, moisture retention, and high-temperature performance. To meet these conditions, it is very important to choose the right raw material. The raw material should have good volume stability. During the heating process, it can be well sintered and reacted with cement such as clay. The aggregate should have an appropriate particle size. And gradation, the critical particle size of general refractory plastic aggregate is less than 10 mm, the amount of aggregate is 55-65%, and the amount of powder is 35%-45%. Through the strength test and moisture retention test, it is found that although the refractory plastics produced with the third-grade high-alumina and the second-grade high-alumina as the main raw materials have higher strength after firing, the moisture retention performance of the material is poor. Therefore, it is determined to use super-grade high-bauxite as the main raw material which requires dense sintering and low impurity content. In order to improve the moisture retention performance, the content of iron oxide in the material should be strictly controlled.

Corundum silicon carbide wear-resistant refractory plastic — Corundum Silicon Carbide Wear Resistant Refractory Plastic

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Influence of the amount of clay and fine powder adding on refractory plastics properties

Adding bonded clay to the refractory plastic, it mainly acts as a cement, and at the same time improves its plasticity and sintering performance. The particle size of clay should generally be less than 200 mesh. Its dosage should be reduced as much as possible while ensuring plastic refractory viscoplasticity and cementation ability. If the amount added is too much, it is easy to cause the linear shrinkage of refractory plastics to increase after high-temperature burning, the softening temperature under load will decrease, and the high-temperature creep will increase. If the amount added is too small, the plasticity of the material cannot be guaranteed. The manufacturer of Rongsheng refractories has determined through experiments that the amount of clay added is 5% to 15%. In order to reduce the change of the burnt line of the plastic refractory, an appropriate amount of kyanite can be added. Because kyanite produces volume expansion at high temperatures, it can offset the partial shrinkage of the plastic refractory, its fineness is 150 mesh, and the adding amount is controlled at about 5%. In order to improve the plasticity and thermal shock performance of the plastic refractory, and further reduce the impurity content in the raw materials, alumina micro powder and silica micro powder are added. This can not only improve the construction performance of the material but also increase the medium-temperature and high-temperature strength of the product. The total addition of the two is generally controlled at 6% to 12%, which is more reasonable.

It is found through experiments that when the plasticity index is about 14%, the plasticity is relatively hard and the construction performance is poor. When the plasticity index is around 26%, the plasticity feels softer and the construction is easier. In order to facilitate the construction and meet the requirements of other performance indicators, through repeated experiments, it is confirmed that the plasticity index of refractory plastic is about 28%.

Choice of refractory plastic binder

In order to make refractory plastics have higher strength and excellent moisture retention properties, Rongsheng refractory manufacturers have experimented with various binders, such as phosphoric acid, water glass, and aluminum sulfate. It can be proved by experiments that using phosphoric acid as a binder can make refractory plastics have higher strength indicators. However, due to the strong acidity of phosphoric acid and the high content of iron oxide in the raw materials, phosphoric acid is easy to produce chemical reactions with iron oxide, which makes the moisture retention performance of refractory plastics worse. Using aluminum sulfate as a binding agent, the plastic refractory has a longer moisture retention performance, but the strength index of the plastic refractory cannot meet the use requirements. Using water glass as a binder, the moisture retention performance of the material is better in a short period of time, but after a long storage time, the construction performance of the plastic refractory will deteriorate. In addition, when the refractory plastic combined with water glass is baked, the strength of the plastic refractory construction body will be adversely affected due to the hard shell formed on the surface. Through repeated experiments, it is determined that phosphoric acid and aluminum sulfate are used in combination so that the moisture retention performance and strength indicators of the plastic refractory can meet the use requirements.

High-Alumina Wear-Resistant Refractory Plastics

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Factors Affecting Humidity Performance of Refractory Plastics

1. Influence of aggregate type

Through continuous moisture retention experiments, it is found that the moisture retention performance of the refractory plastic with super-grade downdraft kiln high alumina aggregate is significantly better than that of other low-grade aggregates. This is due to the dense sintering of super aggregates and the low water absorption of particles.

2. Influence of the type of binder

Binders have the greatest impact on the moisture retention properties of refractory plastics and also play a key role in other properties. If the choice is not appropriate, the plastic refractory will not be able to meet the requirements of use.

Through the experimental research on the moisture retention performance and compressive strength performance of the test block, as well as the comprehensive consideration of the cost of raw materials, phosphoric acid, and aluminum sulfate were finally selected and determined to be used as composite binders. In this way, it can not only meet the moisture retention performance requirements of the refractory plastic but also meet the requirements of medium-temperature and high-temperature strength.

3. Influence of the type of admixture

It can be seen from experiments that adding organic acid (such as oxalic acid), dextrin, and other admixtures can prevent or delay the reaction between the binder and the refractory material, and play a role in prolonging the moisture retention performance of the refractory plastic. Some admixtures are oily, which can effectively reduce the phenomenon of refractory plastic agglomeration, which mainly prolongs the moisturizing performance of the material from the physical aspect. The main binders such as oily moisturizers and phosphoric acid are not miscible, but they can reduce the chance of chemical reaction between phosphoric acid and raw materials so that the moisturizing effect is better.

Used in furnaces such as heating furnaces and annealing furnaces, refractory plastics have certain advantages over castables. It does not need on-site mixing equipment and can be directly constructed. It is viscous and does not flow. It is easier to combine with the old lining when repairing, and it can be partially repaired without a template. Because of its low water content, the requirements for baking conditions are not very strict.

Rongsheng Refractory Plastic Manufacturer

Rongsheng refractory material manufacturer is a refractory material manufacturer with rich production and sales experience. Our refractory products have been sold to more than 80 countries and regions all over the world. For example, South Africa, Chile, Egypt, Colombia, Uzbekistan, Italy, Indonesia, Ukraine, Hungary, Spain, Kenya, Syria, Zambia, Oman, Venezuela, India, Peru, the United States, Ethiopia, etc. Our technical team has rich experience and actual customer cases, whether it is in the solution of refractory lining materials or in the design of refractory materials for the rotary kiln insulation layer. To purchase high-quality refractory plastic materials, please contact us. We can provide free samples and quotations.

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