Why use a shell and tube heat exchanger?
A shell and tube heat exchanger is one of the most common types of heat exchanger because of its versatility. They are highly customisable, with many different types for different applications. This includes different flow types, head configurations, tube plates and materials.
A plant, factory or other business might not have flexibility in the type of shell and tube heat exchanger they must use, but it can still be configured bespoke to provide the best solution to the specific process.
Sterling TT is an expert in designing and manufacturing bespoke heat exchangers for industrial applications. If you’re looking for a heat exchanger for your process, get in touch.
Alternatively, explore our shell and tube heat exchanger product information page.
What is a shell and tube heat exchanger?
A shell and tube heat exchanger consists of a bundle of tubes mounted inside a cylindrical shell. One substance moves inside the tubes, and another of a different temperature flows outside the tubes. This allows conduction to occur between the materials, cooling one and heating the other.
Depending on the design, there will be a different number of passes between the substances and different flows (e.g. counterflow, etc.) to suit the specific substances and requirements of the process.
Why are shell and tube heat exchangers commonly used?
Shell and tube heat exchangers are commonly used due to their very efficient heat exchange rate and because they are easily adapted to suit a range of purposes. They can be designed with a range of custom features to best suit the specific process requirements, improving efficiency and providing flexibility.
For example, engineers can incorporate tubeplates into the design where required, or add extended surface fins. They can be made from different materials according to the substances involved and the demands of the process. Read our blog on the materials used in industrial heat exchangers.
Industries that commonly use shell and tube heat exchangers
Because shell and tube heat exchangers are extremely versatile and can be designed in many different configurations, there are a large number of industries that use them.
These are just some of the industries that commonly use shell and tube heat exchangers.
- Chemical plants
- Oil plants and refineries
- Marine and Defence
- Energy production (including nuclear)
- Food processing and production
The number of industries that use shell and tube heat exchangers is extremely large because these heat exchangers can help with a number of different processes, including:
- Removal of process heat
- Preheating feed water or other liquid
- Condensing process vapour or steam
- Evaporating process liquid or steam
- Cooling hydraulic and lube oil
- Cooling turbines, compressors, and engines
Shell and tube heat exchanger designs
It is in the unique design of each heat exchanger that the true versatility of the product can be seen. By designing each shell and tube heat exchanger to custom requirements, we can ensure that the final product is ideally suited for the process and environment in which it will operate. It’s one of the reasons why heat exchangers are so commonly used.
Let’s examine some of the parts of the heat exchanger to understand the different design configurations.
The shell encases the tube bundle and other internal components.
One of the key aspects of shell design is material. The shell needs to be heat resistant and able to withstand temperature changes. In some processes, it might be essential that it’s corrosion resistant. For example, shell and tube heat exchangers used in seawater or chemical processes often need to be corrosion resistant.
The tube bundle
The tube bundle holds the tube-side medium, which undergoes a change in temperature.
There are a wide variety of ways the tubes and tube bundle are customised within a shell and tube heat exchanger. Material is one, as well as diameter, the number of passes, and the tube shape – such as U-tubes.
The tube bundle can also be removable in some assemblies.
Tube pitch is the distance between the centre of one tube to the centre of the adjacent tube. Tubes can be arranged in triangular or square configurations for different purposes.
Channels or heads
There are a number of different types of heads that can be used on a shell and tube heat exchanger. For example, if frequent maintenance of the heat exchanger will be required, a removable cover channel might be most suitable. Bonnet heads are perhaps the most commonly used on shell and tube heat exchangers that don’t require frequent maintenance.
Tube sheets can add greater flexibility and ensure the heat exchanger can meet more challenging environmental demands.
A fixed tube sheet is a ‘standard’ design used when there are no significant operating challenges.
On the other hand, a double tube sheet, for example, is used where the substances involved must not mix. This is common in chemical operations, among others. The tube sheet design creates an evacuation route for any leaking substance, triggering an alert.
For more information, read ‘heat exchanger tube sheets for challenging operations’.
An expansion joint allows the shell and tube heat exchanger to adapt to changes in temperature, expanding or shrinking as the material gets hotter or colder.
Heat exchangers that handle wide temperature ranges need expansion joints to prevent stress on other elements, which could otherwise lead to damage.
Baffles direct the flow of the substances within the heat exchanger, helping to achieve the most effective velocity for a high heat transfer coefficient. Designing the correct baffle for the product parameters can improve efficiency, reduce fouling and make the equipment fitter for its purpose.
In some configurations, baffles also support the tubes to prevent sagging or damage from vibration.
Extended surface fins
Extended surface fins can be integrated into shell and tube designs to improve efficiency, make the product more compact or make it more economical. They increase the surface area of the exterior side of the tube to enhance the balance of the heat transfer coefficients.
Find out more about enhanced heat exchangers with extended fins.
Versatility and flexibility
Shell and tube heat exchangers are the most common variety of heat exchangers currently used in the industry sector, thanks to their efficiency and cost-effectiveness. Their design configurations are extremely versatile and flexible, so each heat exchanger can be customised to suit its purpose.
Sterling TT are specialists in designing and manufacturing bespoke heat exchangers for industrial applications. Want to know more? View our shell and tube heat exchanger page, or get in touch today by filling the below form.