Pump System Analysis

Background

KBC possesses the expertise to test and consult on pumping systems energy efficiency. The pumping systems in question are mainly used for water in agricultural applications, usually for irrigation.

With the aim of providing useful insight and statistics to potential clients, an analysis was performed on pump systems audited in the past.

Issue

Pumping systems are the most significant electricity users at the production side of an agricultural application.  Most owners are happy when they see the water flowing at the intended supply pressure.  A pumping system converts electrical energy into flow and pressure.  The efficiency of this conversion is not visible to the average operator.  The obvious consequence is a pump system not operating at its optimum, and the owner paying the price for it, literally.

The results of the analysis will serve the purpose of indicating how inefficient pump systems can be when not designed properly.

Audit Methodology

The analysis involved 140 pumps, with rated powers ranging from 7.5 kW to 95 kW. These pumps have all been audited by KBC.  The approach was to check the “vitals” of the system in relation to energy efficiency.

The analysis focused on some key characteristics which can provide the most useful insights. These attributes include:

  • Operating power of motor versus optimal motor power
  • A measure of potential savings
  • Energy used to deliver water

Major Findings

  • The optimal motor power is on average 28% below the operation motor power
  • The operation motor power is on average 15% below rated power.

This means that an average of 28% energy saving is possible if all these pumps should run at their optimum condition.

motorpowergraph

These measurements compared the actual power consumed by the pump, compared to the design power according to the pump specification.  The flow and head were measured at the pump supply point and the efficiency of the irrigation distribution system was not attended to.

A useful attribute to look at is the optimization rating of a pump. The optimization rating is a measure of how well a pump is performing relative to its optimum performance. The pump systems analyzed, were found to operate with an average optimization rating of 57.8%. This is a clear indication of the improvement potential available for the average pump system in practice.

The study revealed an average specific energy value of 0.262 kWh/m3 of water delivered. Taking into account above-mentioned savings potential, the financial benefits of installing an energy efficient pumping system is apparent.

KBC specializes in identifying and consulting on energy efficiency improvement opportunities.