1. 1 ME444 ENGINEERING PIPING SYSTEM DESIGN CHAPTER 6 : PUMPS

2. 2 LAST SESSION 1.PIPING SYSTEM DESIGN PROCEDURE 2.PIPE THICKNESS 3.PIPE SIZING AND SYSTEM PRESSURE DROP

3. 3 CONTENTS 1.Fundamental of Pumps 2.Operating Point 3.Pump Selection 4.Pump Installation

4. 4 1. Fundamental of Pumps When source pressure is not enough to provide desired output, pump is utilized. SOURCEPIPING SYSTEMEND USERS

5. 5 Pump output Flow rate and Pressure rise. Flow rate

6. 6 Pump input and output Output = Flow rate and Pressure rise. Flow rate Input energy

7. 7 Specific Speed

8. 8 Pump performance Dynamic pump Positive displacement pump

9. 9 Pump performance range

10. 10 Performance curves = 0.57 (N s = 1,550) = 3.66 ( N s = 10,000)

11. 11 Steep vs. flat curves  Flat curve for closed loop system with variable flow rate  Steep curve for high head and constant flow rate

12. 12 Affinity law Impeller DiameterImpeller Speed

13. 13 Example of performance curves

14. 14 Example of performance curves

15. 15 Speed of induction motor polesSynchronous speed (rpm) Possible Operating Speed (rpm) 230002850 415001425 61000950 8750712 10600570

16. 16 Standard motor size hpkW 1/80.09 1/60.12 1/40.18 1/30.25 1/20.37 3/40.55 10.75 1.51.1 21.5 2.51.85 32.2 hpkW 43 5.54 7.55.5 107.5 1511 2015 2518.5 3022 4030 5037 6045

17. 17 Effect of Fluid Viscosity

18. 18 Net Positive Suction Head

19. 19 Net Positive Suction Head Required At low pressure, water can become vapor, causing cavitations. Temperature T ( o C) Vapor Pressure (kPa)** 00.87 50.92 101.18 202.29 304.27 407.43 5012.36 6019.89 7031.10 8047.32 9070.16 100101.3 Suction pressure must be maintained above NPSHR to avoid cavitation

20. 20 Net Positive Suction Head Available z Suction lift Vapor pressure Pressure drop in suction piping MUST Maintain NPSHA > NPSHR

21. 21 2. Operating Point Pump performance curve System pressure drop curve Operating point

22. 22 Filling a tank from bottom Pump performance curve

23. 23 Filling a tank from bottom vs. from top Which way fill faster?

24. 24 Throttling the discharge valve Pump performance curve Fully open valve Throttled valve

25. 25 Variable speed drive vs. valve throttling Pump performance curve N1 Throttled valve Fully open valve Pump performance curve N2 Feedback signal

26. 26 VSD for pressure control Valve 1 and 2 open Pump performance curve N2 Pump performance curve N1 Pressure set point All valve open Pressure signal

27. 27 Limitation of VSD Cannot reduce speed System curve Feedback signal

28. 28 Parallel and Serial Connection

29. 29 Response to Parallel Connection

30. 30 Parallel Connection of Pumps with Different Size

31. 31 Utilization of Pressure Tank Pressure Switch Pressure Tank Air Water time Pressure in tank Pump operate Pump stop

32. 32 3. Pump Selection Best Efficiency Energy cost is far beyond the pump cost

33. 33 Example 6.1 Select the suitable pump for Example 5.1 200 lpm @ 50.85m.WG.

34. 34 Example 6.1 (2) 200 lpm 50.85 m Possible selections: NM12 and NM25/20

35. 35 Example 6.1 (2) Select NM12: Trim Diameter to 198 mm

36. 36 Example 6.1 (3) Select NM12: Trim Diameter to 198 mm Pump has efficiency of 49.5% Power consumption 3.2 kW Max power consumption 4kW Select Motor size: 5.5kW Note: follow standard motor size

37. 37 Example 6.1 (4) hpkW 1/80.09 1/60.12 1/40.18 1/30.25 1/20.37 3/40.55 10.75 1.51.1 21.5 2.51.85 32.2 hpkW 43 5.54 7.55.5 107.5 1511 2015 2518.5 3022 4030 5037 6045

38. 38 Example 6.1 (5) Dimension of NM12

39. 39 Example 6.2 Back to example 5.3, if two identical pump of the following curve is installed, predict the operating point. 900lpm@23.1m.WG.

40. 40 Example 6.2 (2) 23.1m.WG. = 21.6m.WG  Variable with flow rate + 1.5 m. WG. Elevation  Constant

41. 41 Example 6.2 (3) 2 pumps in parallel Single pump

42. 42 3. Pump Installation

43. 43 Typical Installation

44. 44 Suction Lift More suction lift = Less NPSHA  Cavitation 5 Meter lift is the maximum possible value Foot Valve Submersible pump

45. 45 Pumping from Tank Vortex prevention plate Drain Mak-up Vent Overflow

46. 46 Eccentric Reducer INCORRECT CORRECT

47. 47 Installation photos

48. 48 Installation photos

49. 49 Homework Exercise 6.1 and 6.2

50. 50 Case Study