What is Coil Wound Heat Exchanger?
In the field of industrial production, as an important process equipment, the performance of the heat exchanger has a vital impact on the entire production process.
Traditional heat exchangers have a simple structure, large size, and inefficiency. In order to overcome these limitations and meet market demand, the coil-wound heat exchanger was developed. Its design completely breaks through the design ideas of traditional shell and tube heat exchangers. From material selection to structural form, it is very different from these traditional heat exchangers.
So, what is a coil wound heat exchanger? What aspects are different from a traditional shell and tube heat exchanger? What are the changes in performance?
Description of Coil Wound Heat Exchanger
The coil wound tube heat exchanger is a new type of heat exchange equipment, which consists of one or more layers of spirally wound tube bundles with opposite winding directions. Multiple heat exchanger tubes are evenly arranged into a cylindrical structure with the same winding direction and a certain spiral angle on the same diameter. The tube bundles spirally wound with the same diameter are defined as one layer.
Structure of Coil Wound Heat Exchanger
The coil-wound heat exchanger consists of a core and shell.
- Core: spiral heat exchange tube bundle, baffle, flow guide device
- Shell: outer shell, tube sheet, flange
Available Material: carbon steel, stainless steel, duplex and super stainless steel, low alloy steel, nickel alloy, titanium and so on
Tube Type: plain tube, corrugated tube
Comparison with Traditional Shell and Tube Heat Exchanger
Structurally, both the coil-wound heat exchanger and the traditional tube heat exchanger are composed of a shell, tube sheet, tube bundle, core metal tubes, and other parts.
The difference between the heat exchangers is that the original straight tubes are changed into spiral tubes. Because the tube bundle is wound and hollow inside, the core metal tubes play the role of supporting the tube bundle.
Design Benefits of Coil Wound Heat Exchanger
Without thermal stress
Due to the spring-like design, the spiral tube can automatically change the distance between the spirals or the diameter of the spiral when it is stressed, so that the stress is compensated. Therefore, the temperature difference on both sides of the spiral tube heat exchanger can be very large. In addition, due to the reasonable stress structure, even if the pressure inside the tube is very high, the pressure acting on the tube wall is not high, resulting in the reactor being able to withstand higher pressure.
Compact structure to save space
The heat exchanger tubes are distributed in a spiral shape, with a compact structure, small size, small footprint, and space-saving; the coil-wound heat exchanger is light and easy to install.
Under the same heat exchange capacity, the volume of the coil wound tube heat exchanger is one-tenth of that of the traditional heat exchanger.
Higher heat transfer performance
When the fluid flows in the spiral tube, the direction of the fluid in the tube often changes due to the winding of the tube, which can form local turbulence and further improve the heat transfer coefficient of the equipment.
The heat transfer coefficient of the coil-wound heat exchanger is generally 2-3 times that of the traditional shell and tube heat exchanger.
Not easy to scale with a low maintenance cost and long maintenance cycle
Due to the unique internal design, the coil wound tube heat exchanger has a better turbulence effect and a low impurity deposition rate.
Long service life
The coil-wound heat exchanger uses the OWEN turbulent buffeting frequency criterion principle and adopts the minimum gap design of the heat exchange tube bundle, which effectively eliminates the turbulent buffeting phenomenon and prolongs the service life of the heat exchanger.
Applications of Coil Wound Heat Exchanger
The coil wound tube heat exchangers are widely used in many fields, such as petrochemicals, energy and electricity, food, medicine, refrigeration, environmental protection, etc.
Natural gas liquefaction
Oil refining
Chemical processing
HVAC
Boiler waste heat recovery
Power generation
Development Trend of Coil Wound Heat Exchanger
Large-scale trend
Due to the special structure of the coil-wound heat exchanger, although its head is very small, the tube can be hundreds of meters long, and some large-scale wound tube heat exchangers have been developed and manufactured. With the continuous development of the large-scale trend of the device, the coil-wound heat exchanger is also required to be larger. However, due to the limitation of the tube, the ordinary shell and tube heat exchanger cannot make the heat exchanger larger.
High temperature trend
The necessary performance of the coil-wound heat exchanger is efficient heat exchange performance, but it is only used in deep cooling devices. The coil-wound heat exchanger made of high-temperature resistant materials has shown superior performance and quality in the application of high-temperature occasions. Its successful cases have greatly broadened the application field of the coil-wound heat exchanger, allowing it to shift from low-temperature application fields to high-temperature application fields. If the medium allows, the coil-wound heat exchanger can also be used in the oil refining industry.
High-pressure trend
The coil-wound heat exchangers are mostly used in places where the shell pressure is high and the tube pressure is low. Generally, the shell pressure can reach 15.0MPa, but the tube pressure is generally less than 5.0MPa. Due to the structural characteristics of the small tube sheets, high shell pressure, and small inlet heads at both ends, the coil-wound heat exchanger can overcome the shortcomings of general high-pressure heat exchangers.
When the pressure is increased, ordinary high-pressure heat exchangers need to increase the shell thickness and significantly improve the strength level of the flange, but the coil-wound heat exchanger can use its extended length to increase the area, and the small tube sheets at both ends also reduce the connecting flange, which will simplify the manufacturing process. Therefore, the coil-wound heat exchanger has great hope of replacing the traditional high-pressure heat exchanger in some industries.