Cast Iron Heat Exchanger

Cast iron heat exchangers are industrial heat exchange devices made with cast iron as the base material. Due to cast iron’s corrosion resistance, heat resistance, and low cost, they have become a practical choice in heat exchange applications under specific conditions.

I. Advantages of Cast Iron Heat Exchanger Materials:

Cast iron (such as gray cast iron and ductile iron) possesses excellent corrosion resistance (good resistance to weak acids, weak alkalis, and seawater), heat resistance (able to withstand high-temperature conditions, such as industrial furnace flue gas waste heat recovery), and a lower cost than precious metals such as stainless steel and copper, making it suitable for heat exchange needs in corrosive media and high-temperature environments.

II. Typical Applications of Cast Iron Heat Exchangers:

Commonly used in chemical, metallurgical, and energy fields, such as industrial furnace flue gas waste heat recovery, seawater desalination preheating, and heat exchange in weak acid/alkali media.

Industrial furnace flue gas waste heat recovery: Utilizing the heat resistance of cast iron, high-temperature flue gas heat is recovered to preheat air/process media; Seawater desalination preheating: Utilizing the corrosion resistance of cast iron, seawater is preheated to reduce energy consumption in subsequent treatment.

III. Cast Iron Heat Exchanger Structure:

Cast iron heat exchangers mostly adopt a tubular structure (such as shell-and-tube or U-tube type), using cast iron tubes as heat exchange tubes, with hot and cold fluids flowing inside/outside the tubes respectively to achieve heat transfer.

IV. Heat Exchange Principle of Cast Iron Heat Exchangers:

The hot fluid flows inside the cast iron tubes, and heat is transferred to the cold fluid outside the tubes through the tube walls (or vice versa). Heat exchange is completed using the thermal conductivity of cast iron (thermal conductivity approximately 50 W/(m·K), lower than copper but much higher than non-metals).

V. Advantages of Cast Iron Heat Exchangers:

Corrosion Resistance: Suitable for corrosive media such as weak acids, weak alkalis, and seawater;
Heat Resistance: Can withstand high-temperature conditions for extended periods (e.g., industrial furnace flue gas temperatures);
Low Cost: Compared to stainless steel and copper tube heat exchangers, manufacturing costs are more advantageous.

Limitations of Cast Iron Heat Exchangers:

Poor Thermal Conductivity: The thermal conductivity of cast iron is much lower than that of copper (approximately 398 W/(m·K)) and aluminum (approximately 237 W/(m·K)), resulting in lower heat exchange efficiency compared to metal tube heat exchangers;
Pressure Resistance: Cast iron tubes have weaker pressure resistance than metal tubes, requiring strict control of the pressure range during design.

VI. Key Design Considerations for Cast Iron Heat Exchangers:

Structure optimization is necessary based on operating conditions (e.g., media corrosivity, temperature, pressure):

Corrosive media: Use corrosion-resistant cast iron (e.g., ductile iron);
High-temperature conditions: Increase tube wall thickness and optimize thermal expansion compensation structures (e.g., U-tube design);
Heat transfer efficiency: Compensate for insufficient thermal conductivity by increasing heat exchange area (e.g., finned tubes, multi-pass design).

VII. Cast Iron Heat Exchangers

Cast iron heat exchangers offer core advantages such as corrosion resistance, heat resistance, and low cost. They achieve heat transfer in corrosive media and high-temperature conditions, making them a practical and adaptable choice in industrial heat exchange. Optimized design based on operating conditions is essential to balance performance and cost.