Pumps

1. Pumps • Outline: • Where are pumps used • Pumps, fans, compressor differences • General HP and mechanical efficiency • Types of Pumps • Displacement • Dynamic • Reading: • Handouts: • Chapter 4 Principles of Process Engineering • Fluide Design Inc. Centrifugal Pump Fundamentals (download) Dr. C. L. Jones Biosystems and Ag. Engineering

2. Pumps, Fans, Compressors--Turbomachines • Turbomachines: change energy level of flowing fluid by means of momentum exchange • 2nd only to electric motors in number • Wide spread in ALL industries • Power units: cars/trucks, tractors • Computers • Grain elevators • Oilfield • Water supply/treatment • Food processing • And……. Dr. C. L. Jones Biosystems and Ag. Engineering

3. Pumps, Fans, Compressors--Turbomachines • Differences between pumps, fans, compressors • Pumps: move liquids • Fans: move gases with little increase in pressure • Compressors: move gases with greater increase in pressure Dr. C. L. Jones Biosystems and Ag. Engineering

4. Mechanical Efficiency • Ratio: • Power Output: • English Units, HP: • Efficiency Dr. C. L. Jones Biosystems and Ag. Engineering

5. Pump example 1 • A pump provides 0.009 m^3/s of water and total head of 10.6 m. Determine the power output of the pump. If the power input is 1310 W, determine the mechanical efficiency of the pump.

6. Pumps • Two types Dr. C. L. Jones Biosystems and Ag. Engineering

7. Displacement Pumps Dr. C. L. Jones Biosystems and Ag. Engineering

8. Displacement Pumps • Reciprocating and Piston Pumps • Crank • Connecting rods • Pistons or plungers • Vol. efficiencies > 97%, Mech. eff. approx. 90% • For more stable flow, increase number of cylinders Dr. C. L. Jones Biosystems and Ag. Engineering

9. Displacement Pumps • Rotary Pumps (gear, lobe, screw, vane) • Most popular: gear pumps • 90%+ mechanical eff. • Relatively constant output Dr. C. L. Jones Biosystems and Ag. Engineering

12. Dynamic Pumps • Centrifugal • Relative simplicity • Mech. eff. as high as 90% • Can handle fluids containing suspended solids • Ease of maintenance…good for food products • 2 parts: impeller and casing • Radial, mixed, axial flow Dr. C. L. Jones Biosystems and Ag. Engineering

13. Dr. C. L. Jones Biosystems and Ag. Engineering

14. Performance Curves Dr. C. L. Jones Biosystems and Ag. Engineering

15. Performance Curves Dr. C. L. Jones Biosystems and Ag. Engineering

16. Centrifugal Pump Affinity Laws Dr. C. L. Jones Biosystems and Ag. Engineering

17. Centrifugal Pump Affinity Laws Dr. C. L. Jones Biosystems and Ag. Engineering

18. Centrifugal Pump Fundamentals • Static head: the height of a column of liquid • Units: feet or meters • Pump imparts velocity to liquid…velocity energy becomes pressure energy leaving the pump. Head developed = vel. energy at the impeller tips. • Why do we use “feet” or “head” instead of “psi” or “pressure”? • Pump with impeller D will raise a liquid to a certain height regardless of weight of liquid Dr. C. L. Jones Biosystems and Ag. Engineering

19. Converting pressure to head in feet Dr. C. L. Jones Biosystems and Ag. Engineering

20. Suction Lift Dr. C. L. Jones Biosystems and Ag. Engineering

21. Suction Head Dr. C. L. Jones Biosystems and Ag. Engineering

22. Static Discharge Head • Static Discharge Head = vertical distance from pump centerline to the point of free discharge or the surface of the liquid in the discharge tank. Dr. C. L. Jones Biosystems and Ag. Engineering

23. Total Static Head • Vertical distance between the free level of the source of supply and the point of free discharge or the free surface of the discharge liquid. Dr. C. L. Jones Biosystems and Ag. Engineering

24. Total Dynamic Suction Lift or Head • (fluid below suction) Static suction lift - velocity head at suction + total friction head in suction line • (fluid above suction) Static suction head + velocity head at pump suction flange – total friction head in suction line • Velocity head = energy of liquid due to motion, Usually insignificant Dr. C. L. Jones Biosystems and Ag. Engineering

25. Total Dynamic Discharge Head • Static discharge head + velocity head at pump discharge flange plus discharge line friction Total Dynamic Discharge Head (TH or TDH) (this is what we design for!!!) • Total dynamic discharge head – total dynamic suction head (tank above suction)…. Or…. • Total dynamic discharge head + total dynamic suction lift (tank below suction) Dr. C. L. Jones Biosystems and Ag. Engineering

26. Total Dynamic Discharge Head (TH or TDH) (this is what we design for!!!) TDH includes friction losses due to piping and velocity Dr. C. L. Jones Biosystems and Ag. Engineering

27. One last item to consider…NPSH (net positive suction head) Dr. C. L. Jones Biosystems and Ag. Engineering

28. NPSHR Dr. C. L. Jones Biosystems and Ag. Engineering

29. NPSHA Dr. C. L. Jones Biosystems and Ag. Engineering

30. NPSHA Dr. C. L. Jones Biosystems and Ag. Engineering

31. Capacity, Power, Efficiency • Capacity Q, gpm = 449 x A, ft2 x V, ft/sec • Where A = cross-sectional area of the pipe in ft2 V = velocity of flow in feet per second • Bhp = actual power delivered to pump shaft by driver • Whp = pump output or hydraulic horsepower Dr. C. L. Jones Biosystems and Ag. Engineering

32. Pump Efficiency • Ratio of whp to bhp: Dr. C. L. Jones Biosystems and Ag. Engineering

33. System Example: 80 ft of 4” ID galv. iron pipe with 3 elbows, 75’ lift, pumps from an open tank, discharges through a pipe to a tank at atm. Pressure (find rate, imp. dia., eff., motor size, rpm) • Ratio of whp to bhp: Dr. C. L. Jones Biosystems and Ag. Engineering

34. Homework Handouthttp://biosystems.okstate.edu/Home/jcarol/Class_Notes/BAE2023_Spring2011/pump hw.pdf

35. Questions??? Dr. C. L. Jones Biosystems and Ag. Engineering