Shell and tube heat exchanger is a most famous type of heat exchanger. In this exchanger, two liquids with different starting temperatures flow through the heat exchanger. One flows through the tube (tube side) and the other flows through the tube but into the shell (shell side). Heat is transferred from one fluid to another through the pipe wall, from the pipe side to the shell side and vice versa. On the shell side or the pipe side, the fluid can be a liquid or a gas. A large heat transfer area must be used for efficient heat transfer, which leads to the use of many tubes. In this way, residual heat can be used. This is an efficient way to save energy.
A shell and tube heat exchanger consists of a shell, tie rod, baffles, tubes, spacers, and tubesheets. The exchangers that only have one phase (liquid or gas) on each side are called single-phase or single-phase heat exchangers. Two-phase heat exchangers can be used to heat a liquid to gas (steam), sometimes called a boiler, or to cool the steam and condense it into a liquid (called a condenser). Steam locomotive boiler is typically a large, cylindrical shell and tube heat exchanger. Large power plants with steam turbines use a shell and tube surface condenser to condense the residual steam and circulate the condensed water from the turbine to a steam generator to convert it to steam.
Shell and Tube Heat Exchanger Parts
The most common parts of the shell and tube heat exchanger are given below:
SHELL
SHELL is an integral part of HE and saves everything. It is designed for internal pressure. Its diameter is larger than the diameter of the tube sheet. Both sides are closed with flanges or welding heads. It’s made of metal.
TUBES
The tube is the 2nd component of the shell and tube heat exchanger that transports hot or cold liquids. Determine the total number of pipes according to your requirements. There are several standard tubes on the market. The MOC is selected according to the shell, tube and plate material to avoid galvanic corrosion.
Most of the hot liquid is retained on the side of the tube to maximize its heat and avoid heat loss.
There are two types of pipes spacing: squares for highly corrosive materials and triangles for transparent materials.
Tubesheet
TUBE SHEET is on both sides of HE. The pipe is attached to it. The HE tube plate is fixed with the fixed tube and cannot be dismantled. The floating pipe enables the HE to be dismantled and cleaned.
BAFFLES
Baffles are used in heat exchangers to increase the fluid turbulence on the shell side and thus to increase the heat transfer coefficient. It also supports the pipe and holds it in place. Various types of baffle arrangements are available.
- Segmented deflector (most popular)
- Aperture deflector
- Disc and donut shaped baffles
The aperture distance is just the distance between the two apertures and has a direct influence on the heat transfer coefficient and the pressure drop and should be determined carefully.
For many high velocity air flows, single sector baffle configurations have undesirably high pressure drops on the shell side. One way to keep the structural advantages of segmented baffles and to reduce the pressure drop (unfortunately the heat transfer coefficient is also reduced somewhat) is with double segmented baffles. The overall effect, depending on the situation, is to halve the local speed. This reduces the pressure drop of a single segmented unit of comparable size by a factor of four.
A three-tier arrangement with a strip cover and a rod cover at the end is available for large enough devices. It is important to always ensure that each pipe is actively restrained at periodic distances to avoid sagging and vibration.
TIE ROD
The TIE ROD is the same tube that is used to hold the joint.
SPACERS
The spacer is attached to the tie rod, holds the deflector in place and prevents vibrations.
