How are individual economizer tubes connected in a boiler system?

In a boiler system, individual economizer tubes are typically connected using U-bends at their ends. This design allows for a more compact arrangement of the tubes, facilitating efficient heat transfer while also providing flexibility in the system. U-bends enable the tubes to change direction, accommodating the layout of the boiler and allowing for thermal expansion and contraction without compromising the integrity of the connections.

Using U-bends helps to distribute the thermal stress more evenly across the joint areas, reducing the likelihood of failures due to cracking or fatigue. This connection method is essential for maintaining the overall efficiency and reliability of the economizer, which plays a crucial role in recovering waste heat from flue gases to preheat the boiler feedwater.

Other methods of connection, such as T-joints, welded joints, or flexible hoses, may not be as effective in this application. T-joints do not provide the necessary directional change needed for tube arrangement, welded joints can be rigid and may not account for thermal expansion adequately, and flexible hoses are generally not suitable for high-temperature applications found in boiler systems. Therefore, the use of U-bends is paramount for the practical and functional design of economizer tube connections in a boiler setup.