Structure and Composition of the Floating Head Heat Exchanger

A floating head heat exchanger is a commonly used thermal exchange device, widely applied in industries such as chemical processing, petroleum, and energy due to its unique structural design. The main structure of a floating head heat exchanger includes the shell, outer head cover flange, floating head tube sheet, hook ring, floating head cover, outer head cover, threaded holes, and steel rings. The core of its design lies in the rational layout of the floating head structure, allowing the device to operate stably in high-temperature and high-pressure environments for extended periods. The primary characteristic of a floating head heat exchanger is its floating head design, which accommodates the thermal expansion and contraction of the tube bundle, effectively reducing thermal stress and extending the equipment's service life. This article will detail the structural composition, key components, and functional features of the floating head heat exchanger to provide a deeper understanding of its design advantages and application scenarios.

Shell

 
The shell is the main body of the floating head heat exchanger, housing the heat exchange tube bundle. It connects to the floating and fixed ends via flanges, forming a closed heat exchange chamber. The shell is typically made of high-strength alloy steel to withstand high pressure and corrosive media.

Floating Head Structure

 
The floating head structure is a critical component of the heat exchanger, primarily consisting of the outer head cover flange, floating head tube sheet, floating head cover, and hook ring. The design of the floating head structure allows the tube bundle to expand and contract freely during operation, effectively reducing thermal stress.
 
Outer Head Cover Flange: This component connects to the floating head cover, forming a sealed chamber. The flange features concave or trapezoidal sealing surfaces to ensure reliable sealing performance.
Floating Head Tube Sheet: This part connects the heat exchange tube bundle and closely fits with the floating head cover. It includes sealing grooves to enhance sealing effectiveness.
Floating Head Cover: The floating head cover seals the floating head tube sheet and, together with the outer head cover flange, forms a complete sealing end. The design of the floating head cover allows for easy maintenance and inspection of the tube bundle during disassembly.

Structure and Function of the Hook Ring

 
The hook ring is a crucial component of the floating head structure, ensuring sealing performance and preventing leakage between media. There are several types of hook rings.

1. Traditional Hook Ring Design

 
The traditional hook ring has a lower distance from the floating head tube sheet, creating dead zones for the shell-side media and potentially reducing the effective heat transfer area. Its larger thickness and longer double-headed bolts contribute to relatively poorer stability. This design is suitable for applications with less stringent sealing requirements but may fall short in high-demand scenarios.

2. Improved Hook Ring Design

 
The improved hook ring features a more advanced design. The angle of the inclined grooves is precisely adjusted to eliminate gaps in the bolts during tightening, ensuring better support and control of the floating head tube sheet. This design significantly enhances sealing performance and structural stability, making it suitable for severe conditions like high temperature and pressure. It also reduces bolt bending deformation, further improving overall sealing effectiveness.

Floating Head Cover Design

 
The floating head cover is a key component responsible for sealing the floating head end, directly affecting the heat exchanger's performance and ease of maintenance. It is typically customized based on the heat exchanger's process requirements, considering fluid flow smoothness and heat exchange efficiency.
 
Multi-Tube Pass Floating Head Cover: In multi-tube pass designs, the floating head cover must ensure sufficient flow area between adjacent tube passes to avoid fluid blockages and maintain heat exchange efficiency.
Single-Tube Pass Floating Head Cover: The single-tube pass cover is simpler in design but requires sufficient internal depth at the pipe center to ensure stable fluid flow under high pressure.
The floating head cover's partition plate is an important part, and its thickness must meet design requirements to prevent deformation or rupture during operation, affecting the heat exchanger's overall performance.

Tube Box Structure and Design

 
The tube box structure of a floating head heat exchanger directly impacts the installation, operation, and maintenance of the equipment. Depending on usage needs, the tube box structure is categorized into several types.
 
Single-Body Tube Box: Suitable for single and multi-tube pass designs, the single-body tube box's main advantage is ease of tube bundle cleaning. However, its complex structure and material requirements mean that larger sizes often require forged components, making the A-type tube box typically used for smaller diameter heat exchangers.
 
Simple Tube Box: The simple tube box has a relatively straightforward structure and lower manufacturing cost, suitable for most applications. However, maintenance requires disassembling the entire tube box, which is less convenient compared to single-body tube boxes.
 
Return Tube Box: Designed for multi-tube pass heat exchangers, the return tube box manages fluid distribution and return flow, ensuring uniform distribution of fluid within the tube bundle.
 
Inlet and Outlet Tube Box: Used for the inlet and outlet of single-tube pass heat exchangers, this compact structure facilitates installation and maintenance.

Tube Box Flat Cover Design

 
The tube box flat cover is an essential part of the tube box, with design variations based on materials, purposes, and cleaning convenience.
 
Integral Flat Cover: Suitable for carbon steel or low alloy steel tube boxes, this design is simple and cost-effective.
Composite Flat Cover: Used for stainless steel or corrosion-resistant alloy tube boxes, suitable for corrosive media environments.
Lined Welded Flat Cover: Employing a lined welded process, this cover is not suitable for vacuum conditions but offers good sealing performance under normal pressure.
 
The floating head heat exchanger, with its flexible structure design, high-temperature and high-pressure resistance, and ease of maintenance, is widely used in high-demand scenarios in industries such as petroleum, chemical processing, and energy. Its floating head design effectively addresses tube bundle thermal expansion, avoiding equipment damage due to thermal stress. Additionally, the optimized designs of the hook ring and floating head cover enhance sealing performance and equipment stability, adapting to varied industrial conditions.
 
With its unique design and excellent performance, the floating head heat exchanger is an indispensable thermal exchange device in industrial production. Understanding its structural composition and component functions can improve the design, selection, and maintenance of this equipment, ensuring efficient and stable operation in practical applications.