Saturday 1 September 2012


Shell and tube heat exchanger

A Shell and Tube heat exchanger
Shell and tube heat exchangers consist of a series of tubes. One set of these tubes contains the fluid that must be either heated or cooled. The second fluid runs over the tubes that are being heated or cooled so that it can either provide the heat or absorb the heat required. A set of tubes is called the tube bundle and can be made up of several types of tubes: plain, longitudinally finned, etc. Shell and tube heat exchangers are typically used for high-pressure applications (with pressures greater than 30 bar and temperatures greater than 260 °C).[2] This is because the shell and tube heat exchangers are robust due to their shape.
There are several thermal design features that are to be taken into account when designing the tubes in the shell and tube heat exchangers. These include:
  • Tube diameter: Using a small tube diameter makes the heat exchanger both economical and compact. However, it is more likely for the heat exchanger to foul up faster and the small size makes mechanical cleaning of the fouling difficult. To prevail over the fouling and cleaning problems, larger tube diameters can be used. Thus to determine the tube diameter, the available space, cost and the fouling nature of the fluids must be considered.
  • Tube thickness: The thickness of the wall of the tubes is usually determined to ensure:
    • There is enough room for corrosion
    • That flow-induced vibration has resistance
    • Axial strength
    • Availability of spare parts
    • Hoop strength (to withstand internal tube pressure)
    • Buckling strength (to withstand overpressure in the shell)
  • Tube length: heat exchangers are usually cheaper when they have a smaller shell diameter and a long tube length. Thus, typically there is an aim to make the heat exchanger as long as physically possible whilst not exceeding production capabilities. However, there are many limitations for this, including the space available at the site where it is going to be used and the need to ensure that there are tubes available in lengths that are twice the required length (so that the tubes can be withdrawn and replaced). Also, it has to be remembered that long, thin tubes are difficult to take out and replace.
  • Tube pitch: when designing the tubes, it is practical to ensure that the tube pitch (i.e., the centre-centre distance of adjoining tubes) is not less than 1.25 times the tubes' outside diameter. A larger tube pitch leads to a larger overall shell diameter which leads to a more expensive heat exchanger.
  • Tube corrugation: this type of tubes, mainly used for the inner tubes, increases the turbulence of the fluids and the effect is very important in the heat transfer giving a better performance.
  • Tube Layout: refers to how tubes are positioned within the shell. There are four main types of tube layout, which are, triangular (30°), rotated triangular (60°), square (90°) and rotated square (45°). The triangular patterns are employed to give greater heat transfer as they force the fluid to flow in a more turbulent fashion around the piping. Square patterns are employed where high fouling is experienced and cleaning is more regular.

Sunday 19 August 2012

Heat Exchanger
Heat exchanger is used for air conditioning, petroleum refineries, natural gas, chemical 
and power plants and sewage. Find manufacturers and dealers of Heat exchanger 
products on made-from-india.com, India’s leading B2B trade directory offering 
exhaustive database of Heat Exchanger Products and Manufacturers listings. View online 
web stores and product showroom of heat exchanger suppliers, heat exchanger 
exporters. 

Breech Lock
A breech-lock is a system for mounting camera lenses to camera bodies. The lens is 
attached to the camera by means of a rotating ring which is used to tighten the lens to the
camera by friction.
Other methods for mounting a lens to a camera include bayonet mount or thread 
mounts.
A breech-lock can also be used to mount firearms.

Shell and tube heat exchanger
- A Shell and Tube heat exchanger
- Main article: Shell and tube heat exchanger

Shell and tube heat exchangers consist of a series of tubes.
One set of these tubes contains the fluid that must be either heated or cooled.
The second fluid runs over the tubes that are being heated or cooled so that it can either provide the heat or absorb the heat required. A set of tubes is called the tube bundle and can be made up of several 
types of tubes: plain, longitudinally finned, etc. Shell and tube heat exchangers are 
typically used for high-pressure applications (with pressures greater than 30 bar and 
temperatures greater than 260 °C).[2] This is because the shell and tube heat exchangers 
are robust due to their shape.
There are several thermal design features that are to be taken into account when 
designing the tubes in the shell and tube heat exchangers.
These include:


Tube diameter: Using a small tube diameter makes the heat exchanger both economical 
and compact. However, it is more likely for the heat exchanger to foul up faster and the 
small size makes mechanical cleaning of the fouling difficult. To prevail over the fouling 
and cleaning problems, larger tube diameters can be used. Thus to determine the tube 
diameter, the available space, cost and the fouling nature of the fluids must be 
considered.
Tube thickness: The thickness of the wall of the tubes is usually determined to ensure:
There is enough room for corrosion
That flow-induced vibration has resistance
Axial strength
Availability of spare parts
Hoop strength (to withstand internal tube pressure)
 Buckling strength (to withstand overpressure in the shell)
Tube length: heat exchangers are usually cheaper when they have a smaller shell 
diameter and a long tube length. Thus, typically there is an aim to make the heat 
exchanger as long as physically possible whilst not exceeding production capabilities. 
However, there are many limitations for this, including the space available at the site 
where it is going to be used and the need to ensure that there are tubes available in 
lengths that are twice the required length (so that the tubes can be withdrawn and 
replaced). Also, it has to be remembered that long, thin tubes are difficult to take out and 
replace.
Tube pitch: when designing the tubes, it is practical to ensure that the tube pitch (i.e., the 
centre-centre distance of adjoining tubes) is not less than 1.25 times the tubes' outside 
diameter. A larger tube pitch leads to a larger overall shell diameter which leads to a 
more expensive heat exchanger.
Tube corrugation: this type of tubes, mainly used for the inner tubes, increases the 
turbulence of the fluids and the effect is very important in the heat transfer giving a better 
performance.
Tube Layout: refers to how tubes are positioned within the shell. There are four main 
types of tube layout, which are, triangular (30°), rotated triangular (60°), square (90°) and 
rotated square (45°). The triangular patterns are employed to give greater heat transfer as they force the fluid to flow in a more turbulent fashion around the piping. Square patterns are employed where high fouling is experienced and cleaning is more regular.
 Baffle Design: baffles are used in shell and tube heat exchangers to direct fluid across 
the tube bundle. They run perpendicularly to the shell and hold the bundle, preventing 
the tubes from sagging over a long length. They can also prevent the tubes from 
vibrating. The most common type of baffle is the segmental baffle. The semicircular 
segmental baffles are oriented at 180 degrees to the adjacent baffles forcing the fluid to 
flow upward and downwards between the tube bundle. Baffle spacing is of large 
thermodynamic concern when designing shell and tube heat exchangers. Baffles must 
be spaced with consideration for the conversion of pressure drop and heat transfer.
For thermo economic optimization it is suggested that the baffles be spaced no closer than 
20% of the shell’s inner diameter. Having baffles spaced too closely causes a greater 
pressure drop because of flow redirection. Consequently having the baffles spaced too 
far apart means that there may be cooler spots in the corners between baffles. It is also 
important to ensure the baffles are spaced close enough that the tubes do not sag. The 
other main type of baffle is the disc and donut baffle which consists of two concentric 
baffles, the outer wider baffle looks like a donut, whilst the inner baffle is shaped as a 
disk. This type of baffle forces the fluid to pass around each side of the disk then through 
the donut baffle generating a different type of fluid flow.

Gas to Gas Heat Exchangers
Condensation of acid from the gas is not a problem during normal operation so there are 
no restrictions on the placement of the hot gas (SO3 gas) on the shell side or tube side of 
the unit.  The decision on which gas goes on the shell or tube side, upflow or downflow 
will be determined from the ducting layout, placement of converter beds or whether the 
exchanger is internal or external to the converter.
Breech Lock Heat Exchangers
High Pressure Heat Exchangers
Power Sector Equipment
Helixchanger
Screw-Plug Heat Exchanger
Heat exchanger manufacturer in india