Category: Insulation Materials

Thermal Insulation Materials for Aluminum Electrolytic Cells

KilnRefractory

Aluminum electrolytic cell is the main thermal equipment for aluminum electrolysis production. Electrolytic aluminum is the process of converting aluminum in alumina into metallic aluminum. There is an outstanding problem in the aluminum electrolytic plant. The bottom of the tank is cold. Improvement measures include blocking the windows in the lower part of the two-story structure, laying bricks within the tank shell frame, and coating the outside of the tank with an insulation layer.

Aluminum electrolytic cells are divided into bottom type and bottomless type according to the structure of the tank. According to the shape of the tank shell, it is divided into square and rectangular. According to the anode structure, it is divided into a prebaked anode and a continuous self-baked anode. According to the conductive mode, it is divided into side conductive and upper conductive.

Aluminum Smelting Furnace
Aluminum Smelting Furnace

The lining materials used in aluminum electrolytic cell-related equipment include calcium silicate boards, clay-insulating refractory bricks, clay refractory bricks, and dry anti-seepage materials. Cathode carbon block, carbon paste, water glass asbestos putty, silicon nitride silicon carbide thermal insulation coating, etc. The heat insulation layer refractory material can be placed between the tank bottom and the asbestos board to increase the heat insulation. The thermal insulation performance is more than five times stronger than calcium silicate boards of the same thickness.

High-Temperature Thermal Insulation Coating for Aluminum Electrolytic Cells

High-temperature thermal insulation coating is processed from specially synthesized inorganic silicate solution, aluminum silicate fiber, heat-reflective material, and selected hollow ceramic beads. Water-based, environmentally friendly, non-toxic, and harmless. The characteristics of high-temperature thermal insulation coating products for aluminum electrolytic cells are as follows:

  1. Thermos bottle thermal insulation mechanism.
  2. The hollow ceramic beads in the coating greatly reduce heat convection.
  3. Inorganic film-forming substances with relatively low thermal conductivity.
  4. Sound insulation and noise reduction, fire-retardant, wear-resistant and pressure-resistant, insulation-resistant and puncture-resistant, acid and alkali-resistant, lightweight, easy construction, and long service life.
RS 500 Thermal Insulating Coating
RS 500 Thermal Insulating Coating

The curing principle of high-temperature thermal insulation coating for aluminum electrolytic cells:

Silicate coatings are composed of a variety of silicates and a small amount of organic and inorganic binders. Its curing principle: a special silicate solution acts as a gelling agent. Aggregation process:

  1. The condensation of silanol and the condensation between silanol and the aluminum hydroxyl group of the silicate. Form a three-dimensional skeleton network.
  2. Silicates are polymerized according to layered and framework molecular-level silicone groups. The mixed metal oxide acts as a space filler between the three-dimensional skeleton of the main body.

Application of High-Temperature Thermal Insulation Coating

  1. Surface painting. High-temperature molds and outer surfaces of injection molding machines. On the inner surface of high-temperature flues and exhaust pipes. Paint the thermal insulation surface of hot water tanks and dye vats.
  2. Ceramic production, ceramic roller kiln, refractory rotary kiln. Cement plant applications, cement rotary kiln, preheater, decomposition furnace.
  3. Steel plant applications, ring furnaces, heating furnaces, and quenching furnaces. Molten steel tundish. Blast furnace workshop steel structure insulation, coke oven.
  4. The inner wall of the furnace shell of the smelting furnace in the metallurgical copper industry. The inner wall of the electrolytic aluminum furnace (aluminum industry).
  5. The outer surface of the power plant turbine shell/shaft seal; and the outer surface of the steam pipe are painted. Petrochemical heating furnace, vacuum heating furnace, cracking furnace.
  6. The top of the boiling furnace is insulated and sealed. Industrial heating furnace. Vacuum furnace insulation.
  7. Driving cab (Crane Crane). Explosion-proof vehicles, asphalt vehicles, engineering vehicles, and military armored vehicle chassis.
  8. Spinning box, high-temperature oven surface. New energy batteries and intermediate frequency furnaces.
Calcium Silicate Board for Aluminum Electrolytic Cell
Calcium Silicate Board for Aluminum Electrolytic Cell

Calcium Silicate Board for Aluminum Electrolytic Cell

Calcium silicate board is a new type of building material, also called “calcium silicate board”, “calcium magnesium silicate board”, “MgO board”, etc. It is a composite building material made of a variety of materials and has multiple functions such as fire protection, waterproofing, sound insulation, heat preservation, and corrosion resistance. Calcium silicate boards can be widely used in various fields such as building walls, roofs, partitions, and floors. It has high economic and social benefits.

The main components of calcium silicate board are inorganic mineral fibers as reinforcing materials, and siliceous, calcium, and other materials as the main materials. These materials are made by high-temperature pressing after certain stabilization treatments. Calcium silicate board has good flexural strength, tensile strength, and compressive strength. At the same time, it also has multiple functions such as fire resistance, corrosion resistance, sound insulation, and heat preservation.

Calcium silicate boards also have a wide range of applications and can be used on walls, roofs, partitions, and floors. Calcium silicate board has the characteristics of water resistance, corrosion resistance, etc. Therefore it is widely used in relatively humid places.

Compared with traditional building materials, the installation process of calcium silicate boards is simpler and faster. When installing calcium silicate boards, you only need to install them directly on the frame, and few other materials are used. Therefore, no construction waste and pollutants will be generated. As a thermal insulation material, calcium silicate boards are also widely used in aluminum electrolytic cells.

How to Solve the Heat Insulation Problem of Cement Kiln?

KilnRefractory

The sintering system of the cement plant has been operating at high temperatures for a long time. Choosing a better insulation material can effectively reduce heat dissipation by lowering the shell temperature without increasing or even reducing the insulation thickness. In order to maintain a better thermal condition of the system, thereby reducing energy consumption, reducing production costs, achieving the goals of energy conservation, environmental protection, and increasing production and efficiency.

The traditional custom for thermal insulation materials in fired systems is to choose microporous calcium silicate boards or ceramic fiber boards. Its thermal insulation performance can no longer meet the current higher needs for thermal insulation and energy saving. New nano-scale microporous thermal insulation materials, referred to as nano-thermal insulation materials, provide technical and material support for the higher requirements for thermal insulation and energy saving of cement kiln firing systems and the improvement of system production capacity.

Inorganic Thermal Insulating Boards in RS Factory
Inorganic Thermal Insulating Boards in RS Factory

Micro-nano Thermal Insulation Materials for Cement Kilns

Recently, cement companies have replaced the original insulation materials of cement burning systems with nano-insulation materials. A good thermal insulation effect has been achieved, which can be used as a reference for other cement companies.

Thermal insulation of the cyclone of the cement kiln preheating and predecomposition system

The cyclone of the preheating and predecomposition system of a cement company was originally insulated with 114mm refractory bricks and 112mm calcium silicate boards. In order to enhance the heat insulation effect of the refractory lining, the company repaired the cyclone on the east side of Line 3 C5. 25 mm nano-insulation boards were used to replace the original calcium silicate boards of the same thickness, keeping the total thickness of the thermal insulation lining unchanged at 112 mm, and the remaining calcium silicate boards with a thickness of 87 mm were used.

Construction of C5 Cyclone Nano Heat Insulation Board
Construction of C5 Cyclone Nano Heat Insulation Board

C5 cyclone insulation lining transformation effect. It was discovered after a period of time that the original calcium silicate board was replaced with nano-insulation board. The heat dissipation loss of the C5 cyclone is reduced by 336W/m2, the shell temperature drops by 21°C, and the heat loss is reduced by 43%. The thermal insulation effect of the refractory lining has been improved.

Improvement of the heat insulation layer in the pre-decomposition zone behind the transition zone of cement rotary kiln

Another cement company’s new special cement line project is to reduce the shell temperature of the rotary kiln’s pre-decomposition zone. In the pre-decomposition zone after the transition zone of the rotary kiln, new nano-insulation panels and grooved brick structures are used to replace the traditional insulation structure. During on-site construction, a 15 mm thick nano-insulation board is inserted into the grooved bricks to form a thermal insulation layer between the rotary kiln shell and the refractory bricks.

Combination form of Rotary Kiln Grooved Bricks and Nano Insulation Panels
Combination form of Rotary Kiln Grooved Bricks and Nano Insulation Panels

The production line uses 15 mm thick nano-insulation panels. Ten days after ignition and production, during normal production of the rotary kiln, the temperature scan of the rotary kiln shell at 35 to 63 m was all green low-temperature areas, and there was no transition color between the two connected areas. It fully reflects the heat insulation effect of the grooved brick composite nano-insulation board. Compared with traditional insulation methods, the surface temperature of the cylinder is reduced by 110°C. The heat dissipation loss is reduced by 4785W/m2, and the annual heat dissipation loss is reduced by 870,000 yuan. The investment can be recovered in about 2 months. Thermal insulation effect of rotary kiln preheat zone.

Infrared Scan of Rotary Kiln Shell
Infrared Scan of Rotary Kiln Shell

Regular maintenance and replacement of refractory bricks and thermal insulation lining in the transition zone of the cement rotary kiln

When a cement company was regularly repairing and replacing refractory bricks in two rotary kiln transition zones, it decided to use grooved bricks combined with 15 mm thick nano-insulation panels to reduce the temperature of the shell of the rotary kiln transition zone. After a period of construction, according to theoretical calculations, the shell temperature of the transition zone of the traditional refractory brick rotary kiln can be reduced by 70 to 110°C. It can greatly reduce the ovality deformation of the rotary kiln shell and reduce energy consumption.

Rongsheng Micro-nano Thermal Insulation Board

Rongsheng Kiln Refractory Factory has accumulated rich experience in the application of thermal insulation materials in various industries. In order to reduce the outer wall temperature of high-energy-consuming and high-temperature industrial furnaces and save production costs, micro-nano thermal insulation materials have been introduced. It better meets the needs of the domestic market and solves many domestic and worldwide thermal insulation problems.

Inorganic Thermal Insulating Boards
Inorganic Thermal Insulating Boards for Cement Rotary Kilns

Nano-thermal insulation material is a nano-scale microporous thermal insulation material produced by using nanotechnology, adding unique anti-infrared radiation materials, and adopting a special process. Compared with traditional micron-sized pore insulation materials such as ceramic fibers and microporous calcium silicate boards, the pores of nano-insulation materials are around 20 nm. The thermal insulation performance at the same temperature is 4 times better than traditional insulation materials.

So far, it has been unanimously proven by many cement companies that the use of nano-insulation materials in the rotary kiln firing system can significantly reduce the heat loss of the rotary kiln barrel. Reducing the kiln operating load and achieving energy saving and consumption reduction are worthy of further research and promotion.