Refractory Materials For Furnace Construction

Refractory Materials for Furnace Construction

Refractory materials for furnace construction are essential components for building industrial kilns and furnaces. They can withstand high temperatures while maintaining the structural integrity and thermal efficiency of the furnaces. Below is a detailed introduction to these materials:

1. Classification

Refractory materials for furnace construction are primarily divided into two categories: shaped refractory products and unshaped refractory materials.

• Shaped Refractory Products: These include refractory bricks and blocks, which come in fixed shapes and sizes, ready for direct use in furnace construction.
• Unshaped Refractory Materials: These include refractory castables, plastics, spray coatings, and ramming materials, which can be cast, rammed, or sprayed on-site to form the desired refractory layer.

2. Common Materials and Applications

Refractory Bricks

• Fireclay Bricks: Widely used for general furnace linings, walls, floors, and flues, with an operating temperature range of 1250–1400°C.
• High Alumina Bricks: Suitable for high-temperature, abrasion-resistant areas or load-bearing sections of furnaces, burner blocks, and other special areas, with a temperature range of 1300–1450°C.
• Insulating Firebricks: Available in fireclay and high-alumina types, these are used for furnace linings not exposed to molten slag or corrosive gases, with operating temperatures of 1150–1300°C and 1200–1300°C, respectively.

Unshaped Refractory Materials

• Dense Unshaped Refractory Materials:
  • Refractory castables are used for furnace linings exposed to flame, pre-cast hangers, and more.
  • Steel-fiber-reinforced castables offer excellent thermal stability, mechanical impact resistance, and abrasion resistance, with operating temperatures of 1000–1200°C.
  • Pure calcium aluminate cement castables are suitable for temperatures up to 1650°C, often used in secondary reformer linings.
  • Heat-resistant, abrasion-resistant castables are designed for specific furnace sections requiring high temperature, abrasion, and erosion resistance, with temperatures up to 1250°C.
• Insulating Unshaped Refractory Materials:
  • Silicate and aluminate cement insulating castables are used as insulation layers in uniquely shaped furnace linings.
  • Refractory ceramic fiber materials, such as castables, sprays, and plastics, feature low thermal conductivity, lightweight, and good volumetric stability, making them ideal for furnace backing layers and hot air duct linings.

3. Material Selection

When selecting refractory materials for furnace construction, factors such as operating temperature, atmosphere, slag properties, and furnace structure must be considered. For example:

• In highly reducing atmospheres, materials with strong reduction resistance should be chosen.
• For areas subject to mechanical impact and abrasion, materials with superior wear resistance and mechanical impact properties are ideal.

4. Construction and Maintenance

Proper construction and maintenance of refractory materials are critical to the performance and lifespan of furnaces. During construction, ensure accurate mixing, casting, ramming, or spraying of materials following relevant standards. For maintenance, regularly inspect refractory layers for wear and erosion, and promptly repair or replace damaged sections.

In conclusion, refractory materials for furnace construction come in a wide variety. Selecting the right materials, adhering to proper construction techniques, and ensuring routine maintenance can guarantee the safe and efficient operation of furnaces.