What is a tubular heat exchanger?
A tubular heat exchanger is a process equipment designed for the heat transfer between two fluids (liquid, steam, gas) or between the surface of a solid and a moving fluid.
The manufacturing of a tubular heat exchanger can be carried out in different qualities of stainless steel or special alloys, being able to withstand high and low working pressures, as well as a wide range of process temperatures. In the manufacturing of heat exchangers, the welding is the key factor of the process. Tubular heat exchangers are very efficient process equipment and their high speeds improve heat transfer considerably.
Design of a tubular heat exchanger
The starting point in the calculation and design of any heat exchange system is the definition of how the thermal properties evolve throughout the process, whether heating or cooling. To calculate a heat exchanger, it is necessary to have certain data, such as the process flow rate, the inlet and outlet temperature and the physical properties of products.
A key factor for the design of heat exchangers is to characterize the behaviour of the product in an accurate way, through laboratory tests, where we determine and analyze the main properties of the product:
- Specific heat.
- Thermal conductivity.
Basic components of a tubular heat exchanger
The basic components of a tubular heat exchanger are as follow:
- Tube bundle:The tube bundle is the set of tubes that provide the heat transfer surface between the fluid that circulates inside the tubes and the fluid that circulates through the shell. In this set of tubes is where the product to be heated is located.
- Tube sheet: The tube sheet is a metal plate that has been perforated or drilled, and where the tubes that form the tubular heat exchanger are housed, which are fixed by expansion or welding. In the event that extra leak protection is required, a double tubular sheet (DTS) can be used.
- Baffles: The main objective of the baffles is to control the general direction of flow on the side of the housing.
- Shell and connections: The shell is the envelope of the second fluid or secondary fluid. The shell is generally a circular section and it is made of a steel plate shaped cylindrical and longitudinally welded. The shell has connections for the inlet and outlet of the secondary fluid.
- Removable heads: The removable heads are elements connected to the tubular plates at both ends of the heat exchanger whose mission is to facilitate the circulation of the product through the tubular beam.
Types of tubular heat exchangers
Depending on its design, the nature of the product and the space available to the plant of destination, the tubular heat exchanger can be grouped into 3 main types:
- Tube-in-tube heat exchanger.
- Annular space heat exchanger.
- Multitube heat exchanger.
The tube-in-tube heat exchanger (also known as double tube heat exchanger) is formed by two concentric tubes. The product flows through the inner tube while the service flows through the space between the two tubes.
The annular space heat exchanger is formed by three or four concentric tubes. The product flows through the central annular space while the service does it through the outer and inner channels.
The multitube heat exchanger is formed by a tube bundle within a shell. The product flows by the inner tubes while the service does it by the external channel.
Uses of a tubular heat exchanger
In general terms, the main uses of a tubular heat exchanger are as follows:
- Raise the temperature of a fluid, using a warmer one.
- Cool a fluid using another that is at a lower temperature.
- Condense gases.
- Evaporate liquids.
Advantages of tubular heat exchangers
The tubular design in heat exchangers represents one of the most traditionally used configurations, due to its good operation and versatility. The main advantages of tubular heat exchangers are as follow:
- Low maintenance costs.
- High working pressure.
- High working temperatures.
- Processing of particulate or fibre products.
- High security in aseptic processes.
- Easy inspection and disassembly.
- Easy to enlarge.
Applications of a tubular heat exchanger
The tubular heat exchanger is a process equipment used in different industries, and its applications are very diverse and varied. The advantages of tubular heat exchangers make them very robust, reliable and low maintenance equipment, due to the absence of joints.
Within the main applications of tubular heat exchangers, from SACOME we highlight the following applications:
- Sanitary applications: Applications destined for the Food Industry with optimized designs to favour a good CIP cleaning (Clean in Place) of the product channel, guaranteeing the best finishes and the drainability.
- Pharmaceutical applications: Applications destined for the Pharmaceutical Industry, in which the roughness certification plays a key role, and whose design is specially designed to avoid cross contamination
- Industrial applications: Applications destined for the Chemical and Petrochemical Industry (Oil and Gas), whereby high priority has been given to ensure long life and high reliability.
Heat Exchangers Technical Documentation
Heat Exchangers for loops of Purified Water (PW) and Water for Injection (WFI) in the pharmaceutical and biotechnology industries.
The importance of rheology in the design of any processing plant is crucial since the sizing of many of the elements composing it is very dependent on this “resistance”, also taking special relevance with food products: heat exchangers, pipes, valves, pumps, mixers, etc.
To design a heat exchanger it is necessary to have certain data, such as the process flow rate, the temperature and the physical properties of products.