Large Diameter High Frequency Welded Spiral Fin Tube

Large Diameter High Frequency Welded Spiral Fin Tube

As a high-efficiency heat exchange element, large diameter high frequency welded spiral fin tubes are widely used in power plant boilers, waste heat recovery, flue gas desulfurization and other systems due to their excellent heat transfer performance, compact structural design and long life. This article will analyze the current status and future trends of this key component from the perspectives of technical principles, manufacturing processes, performance advantages and industry applications.

1. Technical principles and manufacturing processes of large-diameter high-frequency welded spiral finned tubes

High-frequency welding technology uses the skin effect and proximity effect generated by high-frequency current to locally heat the metal material to a molten state in a very short time, and then welds the fins to the base tube through mechanical pressure. Compared with traditional winding or inlay processes, the weld strength of high-frequency welding can reach more than 95% of the parent material, and the heat-affected zone is small, avoiding the degradation of material properties.

The manufacturing difficulty of large-diameter finned tubes (usually refers to base tubes with a diameter of ≥50mm) lies in welding stability and dimensional accuracy control. Its core processes include:

1. Pretreatment of base tube: seamless steel tube or welded steel tube is used, and the surface finish is ensured after rust removal and straightening;

2. High-frequency welding: steel strip (common materials are low-carbon steel, stainless steel or ND steel) is welded to the outer wall of the base tube in a spiral shape through automated equipment, and the welding frequency can reach more than 400kHz;

3. Post-processing process: including stress relief, anti-corrosion coating (such as hot-dip galvanizing, aluminizing, etc.) to improve high-temperature corrosion resistance.

The heat transfer coefficient of high-frequency welded finned tube can reach 3-8 times that of light tube, and the equipment volume can be reduced by more than 30% under the same heat exchange area.

2. Performance advantages and key technological breakthroughs of large diameter high frequency welded spiral finned tubes

1. Efficient heat transfer design

The fins significantly improve the heat exchange efficiency by expanding the surface area (the fin ratio of a single tube can reach 15-25). For example, in a high-temperature flue gas waste heat recovery project of a 1000MW ultra-supercritical unit, after using ND steel finned tubes, the exhaust temperature dropped from 160℃ to 90℃, saving more than 20,000 tons of coal annually.

2. Corrosion resistance and wear resistance

For the high-sulfur flue gas environment of power plants, the new composite finned tubes extend the acid dew point corrosion life to more than 100,000 hours by surface aluminizing (Al-Si alloy layer) or spraying ceramic coating. The experimental data released by Baosteel Research Institute in 2023 showed that the corrosion rate of aluminized finned tubes in a simulated acid rain environment with pH=2 was only 1/20 of that of ordinary carbon steel.

3. Structural reliability

The large-diameter design (Φ60-150mm) reduces the flow resistance and is suitable for large flow conditions. Fatigue tests by the China Special Equipment Inspection and Research Institute show that high-frequency welded finned tubes can withstand 50,000 thermal cycles without cracking at a pressure of 10MPa.

3. Application scenarios of large-diameter high-frequency welded spiral finned tubes in power plant systems

1. Boiler economizer

Replacing traditional light tube economizers, finned tubes can reduce exhaust heat loss by 2%-5%. A power plant renovation case of Huaneng Group shows that after using spiral finned tubes, the boiler efficiency increased by 1.8 percentage points, and the investment payback period was only 1.2 years.

2. Flue gas desulfurization system (FGD)

In the GGH (flue gas reheater), large-diameter finned tubes solve the problem of gypsum scaling and clogging. Datang Environmental Engineering Company uses modular finned tube groups to reduce the pressure drop of the desulfurization system by 15% and extend the maintenance cycle to 3 years.

3. Air-cooling island optimization

In direct air-cooled units, the compact layout of finned tube bundles can reduce the floor space by 40%. A project in Ningxia of the State Energy Group uses bidirectional finned tubes, and the summer back pressure is reduced by 3kPa compared with the traditional design, and the unit output is increased by 5%.

4. Challenges and development trends of large diameter high frequency welded spiral fin tube industry

Despite mature technology, the industry still faces challenges such as cost control (high-end materials rely on imports) and welding process consistency (fin lodging rate needs to be <0.1%).

The future development direction of large-diameter high-frequency welded spiral fin tubes includes:

Material innovation: such as graphene composite coated fin tubes, the heat transfer coefficient in laboratory environment is increased by 50%;

Intelligent manufacturing: real-time control of welding parameters based on industrial Internet, and the yield rate target reaches 99.9%;

Low-carbon application: fin tube heat exchange module coupled with CO₂ capture system.

The high-frequency welding method used by high-frequency welded fin tubes improves the compactness of the fin tubes themselves, while improving the safety and reliability of fin tube radiators.

High frequency welded fin tubes are mainly used in hot air systems and air heat exchange systems in various fields. The excellent heat dissipation of high-frequency welded fin tubes improves the heat dissipation efficiency of the overall radiator and shortens the time required to increase the indoor temperature. Therefore, high-frequency welded fin tubes have certain energy-saving and low-carbon characteristics, saving people a lot of heating costs.

Datang fin tube product’s specification outside diameter from 18 mm to 273 mm finned tube, The process includes high-frequency welded fin tubes, extruded fin tubes, L / L L / K L fin tubes, G -type Embedded fin tubes, low fin tubes, inner fin tubes, elliptical fin tubes, longitudinal fin tube,H type fin tube, the annual capacity can reach 100,000 tons.

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Our R & D department provides the strong technical support and enables us to receive some, O D M projects, and can provide you with drawings, design plans and thermal calculations, service has exceeded more than 3000 enterprises.
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