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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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