4. Heat Exchanger
Heat exchangers (HE) are devices that transfer energy between fluids at
different temperatures by heat transfer.
The fluids can be single or
two phase and depending on the
exchanger type, may be separated
or direct contact.
6. Heat Exchanger Thermodynamics
The design of a heat exchanger is an exercise in thermodynamics, which is the science
that deals with heat energy flow, temperature, and the relationships to other forms of
energy. To understand heat exchanger thermodynamics, a good starting point is to
learn about the three ways in which heat can be transferred – conduction, convection,
and radiation.
8. Advantages
Economizes the whole plant and maximized your energy recovery.
Smaller volume and weight
Higher efficiency
Multi stream and multi pass configuration
Power saving
Safe and reliable in operation
Low pressure drop
Large flow rates
Easy to modify
Easy for maintenance
10. H.E Design Classification
These devices can be classified and categorized in several different ways
based on their design characteristics. The main characteristics by which heat
exchangers can be categorized include:
Flow configuration (parallel,counter,cross,multi)
Transfer process (direct, indirect)
Construction category (recuperative , regenerative)
Heat transfer mechanism (single, double phase)
16. Recuperative vs. regenerative
In a recuperator both media are
separated by a wall through which
heat is transferred directly and it is a
rapid action.
The regenerator represents class of
heat exchangers in which heat is
alternately stored and removed from
a surface
17. Direct Vs. indirect
Recuperative heat exchangers employ either direct contact or indirect contact
transfer processes to exchange heat between fluids.
20. Types of Heat Exchangers
Based on the design characteristics indicated above, there are several
different variants of heat exchangers available. Some of the more common
variants employed throughout industry include:
Shell and tube heat exchangers
Double pipe heat exchangers
Plate heat exchangers
Condensers, evaporators, and boilers
21. Shell and Tube Heat Exchangers
A shell and tube exchanger
consists large number of tubes
mounted inside a cylindrical shell.
Designed on high pressure
Fast in process
Capable to transfer low temp.
to high temp.
Can bear the thermal shocks
Can be use in all application
22. Double pipe heat exchangers
In these exchangers one fluid flows inside the tube and the other fluid flows on the
outside.
low design and maintenance costs
flexibility
low installation costs
Easy to remove large scales
23. Plate heat exchangers
A plate heat exchanger is a type of heat exchanger that uses metal plates to transfer
heat between two fluids.
High heat transfer coefficient and low metal consumption, making heat transfer
effective( 85% to over 90%.).
Compact structure, small size
Great adaptability. ...
Easy to remove, wash and repair.
24. Condensers, evaporators and boilers
Boilers, condensers, and evaporators are heat exchangers which employ a
two-phase heat transfer mechanism.
Condenser are heat exchanging devices which take heated gas or vapor
and cool it to the point of condensation, changing the gas or vapor into a
liquid.
Evaporator and boilers the heat transfer process changes the fluids from
liquid form to gas or vapor form.
26. Steps of Hydro testing
Hydro test is the process to find out the leak from the exchanger
Hydro testing have many steps like:
Isolate exchanger and drain the tube side
Remove the channel /manhole cover
Remove the safety valve of shell side
Install blind or close valves of shell side
Fill the water in shell side
Check the water leak from tubes if found any
tube then plugged them
27. Steps of hydro testing
If not found any tube leak then go to next step of pressure testing
First barricade the area
Install the water pump and pressure gauge on the inlet/outlet way of shell
Start the pressure and watch pressure gauge
Must use the face shield when checking the leak from tube side because the old
plug can be out with the pressure of water
If any leak found then mark and plug
Check the gauge pressure and achieve the
required pressure
Hold the pressure and observe intermittently
28. Steps of hydro testing
If pressure is remain constant so its mean that have no leak
Depressurized the shell with opening of drain valve
Remove the pump
Install the safety valve
Install the channel /manhole cover
Remove barrication and return the permit
De isolate the exchanger
Now exchanger is ready for operation
30. Methods of tube plugging
Tapered Plugs Are Used To Seal The Leaking Tubes In Heat Exchangers. Tapered plugs
offer low cost maintenance and are highly efficient , they offer fastest way to fix leaks in
heat exchangers.
The plugs have different materials as per requirement.
There are two methods for tube plugs:
Temporary method
Permanent method
31. Methods of tube plugging
Temporary method:
In the temporary tube plugging
we install the plug with the
force of hammer.
The second way to fit plug with
tightening of nuts / bolts.
32. Methods of tube plugging
Permanent method:
In this method the plugs are fitted with hammer force but the head of plug is welded
with tube sheet for strength.
33. How many tubes can plugged
10 % tubes can plugged that not disturb the efficiency but after this limit the efficiency
of exchanger is going decrease.
Maximum allowable range is 30 % and after this range we should replace the exchanger
or tube bundle.
