ASME SA179 KL Type Finned Tube With AL1060 Fins For Economizer and Air Heater

ASME SA179 KL Type Finned Tube With AL1060 Fins For Economizer and Air Heater

An ASTM A179 KL Type Finned Tube With AL1060 Fins is a carbon steel core tube (ASTM A179) that has been mechanically altered to have a knurled, footed "KL" fin design, onto which aluminum fins (made from alloy AL1060) are embedded. Its primary purpose is to efficiently transfer heat in applications like economizers, air heaters, and other heat recovery systems.

Here are some detailed breakdowns:

1. Base Tube: ASTM A179

Low-carbon steel. This makes it strong, durable, and cost-effective for pressure-containing duties.

(1) Chemical Composition:

Note: This steel is primarily iron (Fe) with controlled amounts of carbon and manganese. It has low levels of impurities like phosphorus and sulfur. The copper requirement is optional and is only specified when required for enhanced corrosion resistance, typically in certain condenser applications.

(2) Mechanical Properties

These properties are for the finished seamless cold-drawn tube.

2. Fin Type: KL Type

"KL" Type: The "KL" designation refers to a specific kind of knurled, footed, L-foot fin. It is created by a process called "L-foot finning" or "embedment finning".

How it's Made: An aluminum strip (AL1060) is fed into a finning machine. The machine wraps the strip helically around the steel core tube. As it wraps, a set of knurling wheels mechanically deform the base of the fin and the surface of the steel tube, creating a "foot" that is locked into a corresponding groove on the tube.

Key Advantages of KL Type:

• Excellent Mechanical Bond: The knurling process creates a very strong, permanent mechanical connection between the fin and the tube. It is highly resistant to vibration and thermal cycling.
• High Contact Pressure: The process ensures minimal air gaps between the fin and the tube, leading to very low contact resistance and highly efficient heat transfer.
• No Brazing or Welding: It is a purely mechanical process, so there are no issues with dissimilar metal welding or flux corrosion.

3. Fin Material: AL1060 Fins

AL1060 is an Aluminum Association designation for a commercially pure aluminum alloy (99.6% minimum aluminum).

Key Properties:

• Excellent Thermal Conductivity: Aluminum has one of the best thermal conductivity of all metals, making it ideal for dissipating heat from the core tube to the air or gas.
• Lightweight: Aluminum fins reduce the overall weight of the heat exchanger.
• Corrosion Resistance (External): Aluminum forms a protective oxide layer on the sides of the fins, providing excellent resistance to atmospheric corrosion.
• Cost-Effective: AL1060 is a common and cost-effective aluminum alloy.
• High Formability: Its softness makes it suitable for KL knurling and embedding processes.

4. The advantages of combination A179 Core tubes+ Al1060 fins

• Internally: The carbon steel (A179) tube is strong and handles pressurized, often corrosive, fluids well.
• Externally: The aluminum (AL1060) fins are excellent for transferring heat to a gas (like air or flue gas) due to their high conductivity and large surface area, all while being lightweight and corrosion-resistant on the outside.

Specific Applications and Industries:

1. Power Generation and Boiler Plants

This is the most classic application. The tubes are used in:

• Economizers: This is their primary use. An economizer is a heat exchanger located in the boiler flue gas stack. It pre-heats the boiler feedwater before it enters the boiler drum by capturing waste heat from the exhaust gases. This significantly improves the overall efficiency of the boiler system, reducing fuel consumption and operating costs.
• Air Heaters: While other designs are also used, these tubes can be found in systems that pre-heat the combustion air entering the boiler using hot flue gases. Hotter combustion air leads to more efficient burning of fuel.

2. Heat Recovery Steam Generators (HRSGs)

• HRSGs are massive heat exchangers attached to gas turbines. They capture heat from the turbine's extremely hot exhaust to produce steam, which can then drive a steam turbine for additional power (combined cycle) or be used for process heat. The A179/AL1060 KL finned tubes are often used in the economizer and evaporator sections of the HRSG where the temperature is lower.

3. Industrial Process Heating and Drying

Many industrial processes generate hot exhaust gases that contain usable energy.

• Chemical Plants: Recovering heat from process gas streams to pre-heat water or other liquid reactants.
• Pulp and Paper Mills: Used in drying processes and for heat recovery from exhaust systems.
• Food and Beverage Processing: Recovering heat from ovens, dryers, and sterilization equipment.

4. Other Industrial Applications

• Incinerators: Recovering heat from the hot gases produced by waste incineration.
• Marine Applications: Used in exhaust gas boilers on ships to generate steam from the main engine's exhaust, which can be used for heating and other onboard services.