Power saving for centrifugal pumps: inverter, IE3/IE4 engine and performance

With the pump running for many hours, electricity accounts for most of the cost of the life cycle.The two main tools for reducing electricity are to choose the right working point and adjust the speed as needed.

The same law.

When changing the speed n, the flow Q is proportional to n, the pressure column H is proportional to n2, the power P is proportional to n3. Reducing the speed 20% (and 80%) makes the flow 80%, but the power remains only about 51% (0,83 ≈ 0,51), which is saving half of the nominal speed. In fact, if the system has a large static pressure column, the savings are smaller.

Saving with van is very expensive electricity.

Close the discharge valve to reduce the flow so that the pump still creates a high pressure column and is "eaten" by the valve; power does not decrease proportionately.

High performance engines.

Engine achieving IE3 or IE4 grade according to IEC 60034-30-1 reduces losses compared to IE1–IE2. When using the inverter it is necessary to select the appropriate inverter and test the engine's pulse voltage resistance.

Performance of the pump itself.

Hydraulic performance depends on wing design, surface glare and loop gap. In Europe, eco-design regulations set minimum performance levels (MEI) for many types of water pumps, promoting hydraulic optimization by CFD simulation.

The Savings Process.

• Measure flow, pressure columns and actual power.
• Compared to the characteristic line to see if the pump is running away from BEP.
• Cut off wings or replace smaller pumps if the excess pump is large; attach the frequency inverter if the need changes.

Take electricity for example.

Suppose a pump with an axis capacity of 30 kW runs 6,000 hours per year: power of about 180,000 kWh. With a single assumption price of 2,000 VND/kWh, the cost of electricity is about 360 million VND per year. If the actual demand requires only 80% of the flow and is adjusted by the frequency variable, the capacity drops to about 51%, saving approximately 49%, equivalent to more than 170 million VND per year.

Choose a high-performance pump.

Kenflo’s KCP line is hydraulically optimized by CFD simulation and certified as an energy-saving product in China; the two-door suction KPS line is also recognized as an energy-saving and carbon-reduced sample product.The Kenflo pump.Choosing a suitable workplace,Contact us .In order to calculate the frequency.

Frequently asked questions.

Does it damage the engine?

Not if selected correctly; it is necessary to test the pulse voltage resistance of the engine and the cable length, especially when using bearings for high-power pumps.

Should I reduce the diameter of the wing or use a frequency inverter?

Cutting wings are suitable when the excess pump is large and the need is stable; the inverter is suitable when the need changes.