Save costs on pump energy consumption with shaft alignment

In this post, we will use a specific case involving three motor pump groups to show how it is possible to save costs on pump energy consumption with rotating machine alignment systems.

It has long been known among production and maintenance managers that an engine consumes less energy when it is aligned than when it is misaligned. Several studies have been conducted on this topic, with varying results. Energy savings for aligned machines range from 11% to as much as 101%.

Many companies are still unaware of the cost savings in pump energy consumption that can be achieved mainly through shaft alignment. Although they intuitively understand that a machine with less effort to overcome due to misalignment will consume less energy. However, in the field, there are many variables at play that can affect a pump's energy consumption, such as motor efficiency, load, frequency converters, coupling type, proper installation, appropriate lubrication, component wear, appropriate design for the service, etc.

A particular situation that may be of interest in relation to how to measure the effectiveness of alignment in terms of energy cost savings for pumps is the case of a pump room, where three fixed-speed motor-pump groups and another group with a frequency converter were measured, and their energy consumption was measured before and after shaft alignment. Each of the pumps was 30 kW and consumption was measured before and after alignment at the same speeds.

The values obtained for these groups were extrapolated to the entire installed power in the plant's pump room.

For the fixed speed group  energy consumption decreased by an average of 2.753% (4.79 kWh on weekdays / 1.734 kWh on weekends) and for the pump with variable speed drive, energy consumption decreased by 8% (2.08 kWh). In order to estimate the cost reduction For energy consumption, we have to make a couple of assumptions. First, let's assume that these machines operate 5,000 hours per year during normal working hours and 1,200 hours per year on weekends for groups without variable speed drives. The second assumption is to use a rate of €0.11/kWh. With these assumptions, the first group had cost savings of  €2,863.56/year and for the variable speed pump the cost saving is €1,144/year. The formula for the cost saving used in this example is:

Cost savings = Power saved (kWh) x Hours per year x Energy tariff (€/kWh)

We often see misalignment in rotating machines, especially in pumps. This is often the result of poor alignment at the factory or the use of a single rule for aligning all machines.

Although the data shown in this post does not represent a large sample size, it seems to support the theory that alignment can contribute to a  savings in energy consumption by the pumps in a plant. Bear in mind that in this particular case, there are at least 36 units of similar size (and many smaller units) in the plant. If we apply the smallest savings factor achieved (2.5%) to this machine park, the potential energy savings simply by implementing an energy saving plan  Due to alignment, the 36 pumps could easily exceed €40,000. Bear in mind that we are talking about real cash flows that can be allocated to other items in the operations and production department.

If you are interested in learning more about how to save costs on pump energy consumption through shaft alignment and the impact of rotating machine alignment technologies In terms of savings and return on investment for industrial plants, we invite you to subscribe to the Technology newsletter for industry