Heat exchangers allow the transfer of heat between two fluids without direct contact. The main types are shell-and-tube, plate, air-cooled, and spiral. Shell-and-tube exchangers consist of tubes in a shell and are the most common, used across many industries. Plate exchangers use corrugated plates clamped together with gaskets to direct fluid flow. Spiral and air-cooled exchangers provide alternatives for applications where fouling is a problem.

1. Heat Exchangers

2. Heat ExchangersHeat exchangers are one of the most common pieces of equipment found in all plants.

3. Heat Exchangers are components that allow the transfer of heat from one fluid (liquid or gas) to another fluid.

4. In a heat exchanger there is no direct contact between the two fluids. The heat is transferred from the hot fluid to the metal isolating the two fluids and then to the cooler fluid.Types of Heat Exchangers

5. Double-Pipe Exchanger

6. Double PipeSimplest type has one tube inside another - inner tube may have longitudinal fins on the outsideHowever, most have a number of tubes in the outer tube - can have very many tubes thus becoming a shell-and-tube

7. Shell-and-Tube Heat Exchanger

8. Shell-and-Tube Heat Exchangers are the most important type of HE.It is used in almost every type of industry.This type of heat exchanger consists of a set of tubes in a container called a shell.The fluid flowing inside the tubes is called the tube side fluid and the fluid flowing on the outside of the tubes is the shell side fluid.

9. Main Components of Shell-and-Tube Heat Exchangers

10. Some common heat-exchanger termsTube side: Inside the tubes.Shell side: Outside the tubes, between the tubes and the shell.Tube sheet A thick plate provided with holes (one per tube) in which the tubes are fixed.Tube bundle Consists of tubes, tube sheet and baffle platesShell A cylinder of plate in which the tube bundle is placed

12. TEMA Heat Exchangers

13. Shell and Tube Heat Exchangers ConstructionFixed Tube-sheet typeU-tube typeFloating Head type

14. Front head typeA-typeB-typeBAChannel and removable coverBonnet (integral cover)

15. Shell typeE-type F shellLongitudinal baffleFEOne-pass shellTwo-pass shell

16. More shell typesG and H shells normally only used for horizontal thermosyphon reboilersJ and X shells if allowable pressure drop can not be achieved in an E shellGHLongitudinalbafflesSplit flowDouble split flowJXDivided flowCross flow

17. Low-finned TubesFlat end to go into tube sheet and intermediate flat portions for baffle locationsAvailable in variety of metals including stainless steel, titanium and inconels

18. Plate and framePlates hung vertically and clamped in a press or frame.Gaskets direct the streams between alternate plates and prevent external leakagePlates made of stainless steel or higher quality materialPlates corrugated to give points of support and increase heat transfer

19. Plate Heat Exchanger

20. Corrugations on plateimprove heat transfergive rigidity Many points ofcontact and atortuous flow pathChevronWashboardPlate types

21. General view of plate exchanger“Plate exchanger” normally refers to a gasketed plate- and-frame exchanger

22. Flow Arrangement within a PHEGasketsarranged foreach stream toflow betweenalternate plates Alternate plates (often same plate types inverted)

23. Air-Cooled or Fin-Fan Exchanger

24. Air-cooled exchangerAir blown across finned tubes (forced draught type)Can suck air across (induced draught)Finned tubes

25. ACHE bundle

26. Spiral Heat Exchanger

27. Spiral Heat ExchangersSpiral heat exchangers can be used in most applications in the chemical process industryIn many difficult applications where fouling and plugging are problems, a standard shell and tube design may not be effectiveWhile a spiral heat exchanger often has a higher initial cost, it may provide a lower life cycle cost due to lower fouling rates and ease of maintenance

28. A spiral heat exchanger is composed of two long, flat plates wrapped around a mandrel or center tube, creating two concentric spiral channels In a spiral heat exchanger, the hot fluid flows into the center of the unit and spirals outward toward the outer plates while at the same time, the cold fluid enters the periphery and spiral inward, exiting at the center