How to improve pump energy efficiency?
Pump systems are energy intensive, accounting for almost 25% of the energy consumed by electric motors and 20-60% of the total energy used in many industries, water and sewage treatment plants. System changes in pump requirements, normal wear and build-up of pipes over time can lead to reduced efficiency, but it is often overlooked to specify the right pump for a particular application beyond the initial cost. It leads to long-term and higher problems in terms of required electricity costs. Working closely with pump manufacturers, end users, and designers to properly match pump performance and system requirements can often reduce pump energy costs by an average of 20%.
Below, we look at the top factorsthat pump users can do to improve energy efficiency.
Be careful when increasing the size of the pump
If the pump is not operating within 20% of the highest efficiency point,it is usually considered to be large in size, but the operating point is at the BEP flow rate. If it is 50-110%, it is usually considered acceptable. In this range, a margin of error is tolerated if the actual resistance curve is overestimated.
There are several reasons why pumps are oversized. One reason for this is that the pumps are already sized during the planning and construction stages, based on estimates of pipe and fitting losses. There may be an error in the pump specifications due to the need to estimate the requirements of the equipment and the published literature may contain different reference values ??for drag coefficient or fitting loss.
Another reason the pump can be oversized is that the system design can expand over the next few years. Pumps of the right size for the current condition may not be able to meet additional demand in the future. A "safety margin" has been added and larger pumps may be procured and installed to serve future expansion systems.
There are several other reasons for oversized sizes. For example:
• The pump was urgently needed and was out of stock in the correct size.
• For budgetary reasons, the pump was selected from spare stock.
• Oversized pump to allow the accumulation of expected corrosion products in the pipe. This will increase the overall head of the pump.
• "Factor of Safety" can be added to increase pump capacity.
Whatever the reason for the oversized pump, the result is high energy costs for higher performance in terms of flow and pressure, motors requiring more power than possible leads to unnecessary energy consumption.
Engineers can specify a pump with a safety margin in terms of pump performance compared to the actual needs of the application.
Due to the large number, it is not un-common to find applications where oversized pumps are used. Centrifugal pumps are usually known to be 20-30% oversized. Some oversized pumpsare good for smoothing the uncertainty of the design process, but as mentioned above, operating the pump as close to the highest efficiency point possible can result in significant energy efficiency which improves and reduces energy consumption.
The oversized pump can be identified in a variety of ways, including:
• If you need to throttle to meet system requirements.
• High bypass flow rate.
• Pump with flow rate fluctuation of 10 to 20%
• Excessive flow noise
• When bearings and seals need to be replaced frequently
Instead of costly operating procedures such as avoiding throttles to improve energy efficiency, a relatively inexpensive way to reduce the pressure and flow generated is to trim or replace the impeller. In trimming, the impeller is machined to reduce its diameter. However, it should be limited to about 75% of the pump's maximum impeller diameter.
Using with a variable speed drive (VSD) allows the pump to flow near any head or maximum efficiency point by varying the speed of the motor to meet the actual head and flow requirements of the application.
One of the main reasons for using the frequency converter is to improve energy efficiency by reducing unnecessary energy consumption in scenarios where the motor of an oversized pump is decelerated during the specification stage.
The second main reason to use frequency converters to increase energy efficiency is when the application has very different power demands on the pump at different times. The amount of energy you can save using a frequency converter depends on your application and its requirements.
In the water and sewage industry, this often saves more than 30% of energy consumption. When used in combination with an irrigation pump, it can reduce power consumption by up to 75%.
There are several ways to improve pump energy efficiency which are listed above.
Netsol Water can help you in achieving energy efficiency by suggesting an accurate pump for your system.