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Heat Exchagers Presentation.pdf
- 1. Heat Exchanger WAQAR AHMED HUBCO POWER PLANT
- 2. Contents Introduction Thermodynamics Advantages of H.E Design Classifications Types of heat exchanger Steps of hydro testing Methods of tube plugging
- 3. Introduction
- 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)
- 11. Flow Configuration Parallel flow (Co Current Flow) Counter flow Cross flow Cross Counter/Multi Pass Flow
- 12. Why we prefer the counter flow more than parallel flow????????
- 15. Construction Category Recuperative vs. regenerative Direct vs. Indirect Static vs. Dynamic
- 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.
- 34. Any Question???
- 35. Thank you