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BAE4400 Topics in Processing

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Presentation on theme: "BAE4400 Topics in Processing"— Presentation transcript:

1 BAE4400 Topics in Processing
Fall 2006 August 22 through September 21 1 hour credit Dr. C. L. Jones Biosystems and Ag. Engineering

2 Review from Lecture 1: Pumps
Difference between pumps, fans, and compressors Mechanical Efficiency Dr. C. L. Jones Biosystems and Ag. Engineering

3 Review from Lecture 1: Pumps
Two types Flow rates Pressure Flow characteristics Displacement - plunger - piston - rotary Low High Pulsating Dynamic - centrifugal - jet - airlift Steady Flow Dr. C. L. Jones Biosystems and Ag. Engineering

4 Review from Lecture 1: Pumps
Recip Pumps have a crank, connecting rods, and pistons or plungers Rotary gear pumps provide more constant output Recip Pump eqtns. Dr. C. L. Jones Biosystems and Ag. Engineering

5 Review: Dynamic Pumps Centrifugal Relative simplicity
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

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

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

8 Review: Centrifugal Pump Affinity Laws
Dr. C. L. Jones Biosystems and Ag. Engineering

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

10 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

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

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

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

14 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

15 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

16 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

17 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

18 TDH includes friction losses due to piping and velocity
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

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

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

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

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

23 Capacity, Power, Efficiency
Capacity Q, gpm = 449 x A, ft2 x V, ft/sec Where A = cross-sectional area of the pipe in ft 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

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

25 System Example: 80 ft of 4” ID galv
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

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


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