Different types of stream traps

Different Types of Steam Traps & their Functions

1. DIFFERENT TYPES OF STREAM TRAPS Prem Baboo Sr. Manager (Prod) National Fertilizers Ltd. India F.I.E., Institution of Engineers (India) Technical Advisor & an Expert for www.ureaknowhow.com

2. STEAM TRAPS

3. STEAM TRAP The purpose of a steam trap is not as the name may indicate to trap steam, but rather to trap condensate in a steam line. The trap should be closed when steam is present in the line. It is usually important that the traps perform closing and opening quickly to reduce steam and condensate losses.

4. There are three types of steam traps, they are: 1. Ball float & bucket traps are mechanical steam traps . They operate be response to the difference density between and steam and condensate 2. Thermostatic steam traps operate by noticing the temperature difference between condensate and steam. 3. Thermodynamic traps operate by the difference in thermodynamic energy between steam and condensate.

5. Mechanical steam traps . Ball Float Trap Inverted Bucket Float Open Bucket Float

6. Ball float steam trap

7. Ball  Float  Steam  Trap

8. Open Bucket Float

9. Open Bucket Float

10. Advantages Discharge condensate continuously as rapidly as its forms. High air venting capacity through auxiliary balanced- pressure air vent. Which is self adjusting for varying steam pressure. High thermal efficiency at both light and heavy loads. Steam lock release facility available. Fair resistance to water hammer. Wide range of orifices to suit in let pressure.

11. Limitations Can not be used on high degree of superheat. Application subjected to freezing must be protected with insulation and S L R. Water hammer can damage the float.

12. Typical Applications: Air unit heater. Hot water heater. Heat exchangers Converters Reboilers Jacketed pans

13. Inverted Bucket Float Main valve Inverted bucket

14. Inverted Bucket Float

15. Advantages Fair resistance to water hammer. Can be made for high pressures.

16. Limitations Low thermal efficiency under varying loads and pressures, some steam loss for operation. Must maintain water seal to avoid continuous discharge of steam. Must be protected from freezing. Cannot discharge condensate continuously as it forms.

17. Typical Application . High pressure indoor steam main drips and submerged heating coils.

18. Operation

19. Liquid expansion steam trap Balanced pressure steam trap · Bimetallic steam trap Thermostatic Steam Traps

20. Liquid expansion steam trap

21. Installation of a liquid expansion steam trap

22. Advantages It is able to withstand vibration and water hammer conditions. Prevents flooding of heating surface during cold startup. Liquid expansion traps can be adjusted to discharge at low temperatures, giving an excellent 'cold drain' facility.

23. Limitations Not pressure balance. Since the liquid expansion trap discharges condensate at a temperature of 100°C or below, it should never be used on applications which demand immediate removal of condensate from the steam space. The liquid expansion trap is not normally a trapping solution on its own, as it usually requires another steam trap to operate in parallel.

24. Balanced pressure steam trap with replaceable capsule

25. Balanced pressure capsule arrangement

26. Operation of balanced pressure steam trap capsule

27. Advantages High air venting capacity for fast startups. Self adjusting to all pressures within its range. Sealed capsule is free from maintenance. Doubles as an air vents and vacuum breaker. The valve is fully open on start-up, allowing air and other non-condensable gases to be discharged freely and giving maximum condensate removal when the load is greatest. Trap maintenance is simple. The capsule and valve seat are easily removed, and replacements can be fitted in a few minutes without removing the trap from the line.

28. Limitations In common with all other thermostatic traps, the balanced pressure type does not open until the condensate temperature has dropped below steam temperature (the exact temperature difference being determined by the fluid used to fill the element). This is clearly a disadvantage if the steam trap is chosen for an application in which water logging of the steam space can not be tolerated, for example; mains drainage, heat exchangers, critical tracing.

29. Typical Application: Steam radiators Steam tracer and jacketed pipe . Air venting of process equipment Steam heater.

30. Bimetallic steam trap

31. Response of a single element bimetal steam trap

32. Bimetal steam trap with two leaf element

33. Response of a two leaf element

34. Multi-cross elements of bimetallic steam traps

35. Advantages Bimetallic steam traps are usually compact, yet can have a large condensate capacity. Good air venting capability and maximum condensate discharge capacity under 'start-up' conditions. Bimetallic steam traps are usually able to withstand water hammer, corrosive condensate, and high steam pressures. Maintenance of this type of steam trap presents few problems, as the internals can be replaced without removing the trap body from the line.

36. Limitations Bimetallic steam traps are not suitable for fitting to process plants where immediate condensate removal is vital for maximum output to be achieved Bimetallic steam traps do not respond quickly to changes in load or pressure because the element is slow to react.

37. Bimetallic steam traps

38. Bimetallic steam trap with cooling leg

39. Thermodynamic Steam Traps   · Traditional thermodynamic steam trap · Impulse steam trap · Labyrinth steam trap · Fixed orifice traps

40. Thermodynamic steam trap

41. Advantages They are compact, simple, lightweight and have a large condensate capacity for their size. Thermodynamic traps can be used on high pressure and superheated steam and are not affected by water hammer or vibration. As the disc is the only moving part, maintenance can easily be carried out without removing the trap from the line.

42. Limitations: Thermodynamic steam traps will not work positively on very low differential pressures. Thermodynamic traps can discharge a large amount of air on 'start-up' if the inlet pressure builds up slowly. However, rapid pressure build-up will cause high velocity air to shut the trap in the same way as steam, and it will 'air-bind'. In this case a separate thermostatic air vent can be fitted in parallel with the trap

43. Impulse steam trap

44. Advantages Impulse traps have a substantial condensate handling capacity for their size. They will work over a wide range of steam pressures without any change in valve size and can be used on high pressure and superheated steam. They are good at venting air and cannot 'air-bind'.

45. Limitations: Impulse traps cannot give a dead tight shut-off and will blow steam on very light loads. They are easily affected by any dirt which enters the trap body due to the extremely small clearance between the piston and the cylinder. The traps can pulsate on light load causing noise, water hammer and even mechanical damage to the valve itself.

46. Labyrinth steam trap

47. Advantages This type of trap is comparatively small in relation to its capacity and there is little potential for mechanical failure since there are no automatic parts.

48. Limitations: The labyrinth trap has to be adjusted manually whenever there is a significant variation in either steam pressure or condensate load

49. Ball-float  steam  trap

50. Bucket-type steam trap

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