Can Lightweight Castables Used as Insulation Layers for Industrial Furnaces Reduce Heat Consumption?

Lightweight castables have lower thermal conductivity than heavy castables and significantly reduce the weight of the furnace lining. The diffusion rate of combustion temperature in industrial furnaces can be reduced by about 30% compared to heavy castables. Therefore, using lightweight insulating castables as insulation layers can effectively reduce the heat loss of industrial furnace linings.

Lightweight Castable Refractory for Furnaces
Lightweight Castable Refractory for Furnaces

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    Lightweight Castables as Insulation for Industrial Furnaces

    Lightweight castables are the first layer of material that adheres to the furnace shell in the kiln lining. High-end lightweight castables, such as hollow alumina sphere castables and lightweight mullite refractory castables, can also be used directly as a working layer on the lining of some lightweight kilns. This reduces furnace weight, lowers heat consumption, and saves energy costs.

    The thickness of lightweight castables used as insulation should be 80mm-150mm. Thicknesses below 50mm will result in poor installation and ineffective insulation. Using lightweight castables for lining pipes and chimneys is also a poor choice. Castables with a specific gravity of approximately 1.5 can serve as both an insulation layer and a working layer. This reduces weight while meeting the requirements for chimney and pipe linings.

    Lightweight castables are used at different temperatures: low temperatures (600-900°C), medium temperatures (900-1200°C), and high temperatures (1200°C). High-temperature insulation layers require high-quality lightweight materials, such as lightweight mullite and hollow alumina sphere castables. Commonly used materials include vermiculite, perlite, and ceramsite. These materials have an operating temperature of approximately 1000°C and cannot be used at high temperatures. Lightweight mullite and corundum-mullite castables can be used at temperatures between 1350°C and 1500°C, allowing for direct use in the working layer.

    Lightweight castables lack the refractoriness, compressive strength, and flexural strength of heavier castables. However, their low thermal conductivity provides excellent insulation. Choosing the right lightweight material for different temperatures and kiln linings can effectively insulate and reduce energy consumption.

    Lightweight Insulation Castable
    Lightweight Insulation Castable

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      Significant Features of Low Thermal Conductivity Castables

      Low thermal conductivity castables are unique refractory materials that maintain low bulk density and low thermal conductivity even at high temperatures, while also offering excellent thermal insulation. Unlike conventional lightweight castables, whose bulk density increases with increasing temperature, low thermal conductivity castables maintain a low bulk density even at high temperatures. Their light weight effectively reduces the weight of equipment, which is crucial for the installation and operation of large-scale industrial equipment. Furthermore, their excellent thermal insulation properties ensure more uniform furnace temperature distribution, thereby saving energy and reducing production costs.

      In terms of technical performance, low thermal conductivity castables offer the dual advantages of low bulk density and high refractory strength, a true innovation in themselves. They offer strong overall performance, excellent spalling resistance, a long service life, and can be repaired and processed into various shapes as needed. They can also be used to construct integral furnace linings, greatly facilitating the maintenance and construction of industrial furnaces.

      Wide Application Areas and Energy-Saving Advantages

      Low thermal conductivity castables have a wide range of applications across numerous industries. They are widely used in industrial furnaces and thermal equipment in industries such as metallurgy, machinery, power generation, chemicals, and petroleum. Compared to conventional lightweight castables, using low thermal conductivity castables can achieve energy savings of over 20%, a significant saving for energy-intensive industries. Especially in applications such as petroleum and petrochemical furnaces, where material performance requirements are more stringent, low thermal conductivity castables require a lower bulk density and adhere to stricter quality standards. Therefore, compared to lightweight castables used in other industries, low thermal conductivity castables for petroleum and petrochemical furnaces are of higher quality and relatively higher price. However, the energy-saving benefits and equipment protection they provide are well worth the effort.

      Easy Construction

      Low thermal conductivity castables are relatively easy to apply. Manufacturers carefully select the aggregate particle size. An appropriate particle size helps enhance the compressive strength of lightweight castables. Excessively large particle sizes can negatively impact the construction process. By optimizing the particle size, low thermal conductivity castables can be constructed more smoothly, reducing difficulties and problems during construction, improving construction efficiency, and ensuring construction quality.

      Considerations for Lightweight Castable Pipe Installation

      Lightweight castables provide insulation. For pipe use, their bulk density generally must be no less than 1.2 kg/m³. Specific gravity of 1.5 is more common. When used in pipes, installation is limited by the pipe diameter, making it difficult for workers to work within the pipe.

      The Pipe Insulation
      The Pipe Insulation

      1. Pay attention to the insulation layer.

      Applying the insulation layer to the insulation is also challenging. The pipe insulation in the image above is applied irregularly, and the anchors are not suitable for use. Anchors must be painted. If not, plastic caps must be placed on them. Otherwise, rust will occur, shortening their lifespan.

      If this occurs, there is a remedy: apply a layer of plastic film to the surface of the insulation. This prevents moisture from penetrating the insulation during baking after the lightweight castable is applied. If moisture seeps into the insulation, even after drying, the insulation’s effectiveness will be reduced.

      2. Pay attention to the proportions added during construction.

      When applying lightweight materials, the water ratio must be carefully considered. If too little water is added, some of the base materials, due to their light weight, will be difficult to apply and will not set easily. Adding too much water will affect the strength of the material in the final application.

      3. Mix the aggregate and powder before construction.

      During on-site construction, first mix the aggregate and powder, then add the binder. Then, strictly follow the manufacturer’s water ratios and mix the lightweight castable. After mixing, verify that the castable has good fluidity before vibrating. Generally, the water content for lightweight castables is 15-17%. Some manufacturers, due to the light weight of the lightweight castable, may sprinkle some water during production to facilitate production control.

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        Advantages and Applications of Lightweight Insulating Castables

        Lightweight insulation castables are composed of high-quality, high-strength raw materials, aggregates and ultra-fine powders, and compound additives. Because the light-weight insulation castable is a powdery and granular refractory material made of certain refractory materials such as alumina and some binders. It has high fluidity and is mainly formed by pouring in construction. Lightweight insulating castables have the advantages of high strength, small volume density, low thermal conductivity, good insulation performance, and convenient construction. It is an ideal choice for industrial boiler insulation materials.

        Lightweight Insulation Refractory Castable

        RS Lightweight Insulating Castable for Sale
        RS Lightweight Insulating Castable for Sale

        Construction method: vibration or manual ramming construction.

        Main function: Insulation and heat insulation to reduce the external temperature of the furnace wall.

        Q: How to mix light-weight insulation castable?

        A: The mixing of castables requires the use of forced mixers and special mixers.

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          Advantages of Lightweight Insulating Castable

          The light-weight castable insulation is made of aluminate cement, high-alumina fine material, ceramsite, plus several additives. It has the advantages of high refractoriness, high strength, and low thermal conductivity. The heat preservation casting material of the invention has the characteristics of low thermal conductivity and small volume density, which can reduce the heat and heat energy consumption of industrial kilns and reduce the weight of the furnace lining. In the high-temperature light-weight insulating castable, the raw material of the high-temperature light-weight castable that can be used above 1200°C is a porous material. Mullite, corundum, high aluminum, siliceous and magnesia and other porous clinker or light refractory brick. This castable can be directly used in the lining of 1350℃ atmosphere furnace.

          Insulating castable supplier
          RS Insulating Castables Supplier

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            Lightweight thermal insulation castable has the following advantages:

            1. The high-temperature resistance and high strength.
            2. Low thermal conductivity.
            3. The small volume density, reduce kiln heat consumption.
            4. Convenient construction and reduce labor intensity.
            5. Light texture, reduce the weight of kiln lining.
            6. resistant to acid and acid gas corrosion.
            7. Characteristics of heat insulation, heat preservation, and low water absorption.

            In addition, the lightweight insulating refractory castable is not only easy to construct but also the most ideal product for construction with alkali-resistant parts at high temperatures. Moreover, the workability is good, the bonding force is strong, and the initial setting time and the construction operable time are long. The strength increases quickly, the impermeability is strong, no acidification treatment is needed, and it is easy to ensure the denseness and fullness of the masonry gray joints. Can significantly improve the airtightness, integrity, and anti-corrosion ability of the chimney lining wall. It is an ideal cementing material for a high chimney, high-temperature flue, and air duct lining.

            The Use of Light-weight Insulation Castable

            It is suitable for unshaped refractory materials formed by pouring. It is easy to ensure the denseness and fullness of the masonry gray joints, which can significantly improve the airtightness, integrity, and corrosion resistance of the chimney lining wall. It is suitable for a high chimney, high-temperature flue, and air duct lining. Lightweight insulating castables are mainly used for lining thermal insulation devices such as high-temperature industrial kiln insulation. It can also be used in acid-resistant projects such as acid-resistant tanks and tanks in petroleum, chemical, nonferrous metallurgy, and other industries.

            Mullite Insulating Castable
            Mullite Insulating Castable

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              Lightweight Insulating Castables Manufacturer

              Rongsheng refractory castable manufacturer has an annual output of 80,000 tons’ production workshop. As a manufacturer of high-quality refractory castables, the light-weight heat-insulating castables produced have the advantages of moderate strength and good insulation performance. Lightweight insulating castable is made of aluminate cement, high-alumina fine material, ceramsite, and some additives. Lightweight insulating castables have the characteristics of lightweight, high compressive strength, acid and acid gas corrosion resistance, heat insulation, heat preservation, and low count rate. In addition, Rongsheng’s acid-resistant bricks, acid-resistant clay and wipe fabrics, acid-resistant bricks, acid-resistant clay, and wipe fabrics are self-developed refractory materials suitable for thermal insulation of power plant boiler chimneys and heating network pipes. They have the characteristics of acid corrosion resistance, temperature resistance, heat resistance stability, and convenient construction.

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