Concepts for estimating pumping energy costs:Flow regulation by varying speed

Flow regulation by varying speed

The resulting curves for specific energy as a function of speed for three different system curves are shown in Figure 5.2. Figure 5.3 shows the cor­ responding system curves. The intersection of the two reduced speed pump curves with the system curves B and C, indicate shut off head where the specific energy goes towards infinity. It can be seen that the savings potential is very large at low static head, curve A, whereas care has to be taken in high static head situations, represented by curve C.

When the speed is low enough to cause the pump to operate at or close to shut-off head, the specific energy always goes towards infinity. In case A, this will occur since the motor-drive efficiency will approach zero with no load.

VARIABLE SPEED PUMPING-0737

The line D indicates the specific energy at which the pump is operating when using on-off control. When operating below this line, energy savings will be realized compared to on-off operation.

Related posts:

Case studies:VSD in a wastewater pumping scheme
Case studies:Variable speed drives on water pumps supplying a ring main at a domestic appliance fact...
Introduction to pneumatic conveying and the guide:Recent developments
Pressure and flow:Pascal's law.
ROUBLESHOOTING PNEUMA TIC CIRCUITS:GLOSSARY
Hydraulic cylinders:General
Hydraulic motors:Piston motors.
Hydraulic fluids.
Application notes: Regeneration ,Counterbalance and dynamic braking ,Pilot-operated check valves ,P...
Hydraulic Pumps and Pressure Regulation:Piston pumps
Air Compressors, Air Treatment and Pressure Regulation:compressor types and Piston compressors
PROPERTIES OF PURE SUBSTANCES:OTHER EQUATIONS OF STATE
POWER AND REFRIGER A TION CYCLES:AIR-STANDARD ASSUMPTIONS
POWER AND REFRIGER A TION CYCLES: THE IDEAL CYCLE FOR SPARK-IGNITION ENGINES
SUMMARY OF FORCED CONVECTION

Leave a comment

Your email address will not be published. Required fields are marked *