What is a tubular heat exchanger?
A heat exchanger is a process equipment designed to transfer heat between two fluids (liquid, vapor, gas) or between the surface of a solid and a moving fluid.
The manufacture of the heat exchanger can be performed in different grades of stainless steel or special alloys and can withstand high and low operating pressures and a wide range of process temperatures. In the manufacture of heat exchangers, welding is a key aspect of the process. The tubular heat exchangers are very efficient process equipment and high speeds improve heat transfer considerably.
Sizing of a tubular heat exchanger
To carry out the sizing of a heat exchanger, it is necessary to have certain starting data, such as the process flow, the initial and final temperature, as well as the physical properties of the product.
An essential factor for the calculation and sizing of a tubular heat exchanger is to be able to characterize the behavior of the product in a reliable and precise way, through laboratory tests, where the main properties of the product can be determined, such as:
- Specific heat.
- Thermal conductivity.
What are the basic components of a tubular heat exchanger?
The basic components of a tubular heat exchanger are:
- Tube bundle: The tube bundle is the set of tubes that provide the heat transfer surface between the fluid that circulates inside it and the fluid that circulates through the casing. This set of tubes is where the product to be heated is located.
- Tubular plate: The tubular plate is a metal plate that has been drilled or drilled, where the tubes that form the tubular heat exchanger are housed, which are fixed by expansion or welding. In the event that extra protection against leaks is required, a double tube plate can be used.
- Baffles: The main purpose of baffles is to control the general direction of flow from the shell side.
- Housing and connections: The housing is the envelope of the second fluid or secondary fluid. The casing is generally circular in section and is made of a steel plate formed in a cylindrical shape and longitudinally welded. The housing 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 tube bundle.
Types of tubular heat exchangers
Depending on its design, the nature of the product and the space available at the destination installation, the tubular heat exchanger can be grouped into 3 main groups:
- Tube-in-tube heat exchanger.
- Annular space heat exchanger.
- Multitubular heat exchanger.
The tube-in-tube heat exchanger (also known as a double tube heat exchanger) is made up of two concentric tubes of different diameter, where the product circulates through the inner tube and the service does so through the space between both tubes.
The annular space heat exchanger consists of three or four concentric tubes. The product flows through the central annular space while the service flows through the outer and inner channels.
The multitubular heat exchanger is formed by a tube bundle within a shell. The product flows through the inner tubes, while the service flows through the outer channel.
Main uses of the heat exchanger
Generally speaking, the main uses of heat exchangers are:
- Raise the temperature of a fluid, using a hotter one.
- Cool a fluid using another that is cooler.
- Condense gases.
- Evaporate liquids.