Energy efficiency is a topic that should be on everyone’s agenda. Environmental concerns, as well as the impact on business overheads, means that reducing energy consumption is vital within industrial plants. Castle Pumps shares seven ways users can improve the efficiency of their pumps.
Findings shared by the US Department of Energy suggest that 16% of a typical industrial facility’s electricity costs are generated by its pumping systems. So, pumps have a large part to play the global drive to reduce energy consumption. But how can you improve the energy efficiency of your pump?
Avoid oversizing
Oversizing a pump during specification is common to cater for any uncertainties in the design process regarding the duty required from the pump. However, as a higher performance in terms of flow and pressure requires the pump’s motor to run at a higher power, which uses more energy than necessary. So, a pump should be selected than can be run as close to it’s Best Efficiency Point (BEP) as possible.
Trim the impeller
If a pump has been oversized, then sometimes a throttling valve is used to achieve the lower duty requirements. But this is not as energy efficient as trimming the impeller, which is a relatively cost-effective way of reducing the pressure and flow. However, impeller trimming is not necessarily the most energy-efficient solution because when an impeller is shaved, the casing clearance gets larger. For that reason, variable frequency drives are often selected for peak efficiency.
Use a variable frequency drive
The purpose of a variable frequency drive is to vary the speed of a pump’s motor to achieve the exact performance requirements of the application. This reduces energy waste in two ways. Firstly, it can slow the motor on an oversized pump. Secondly, it can control a pump in situations where there are differing duty requirements at different times, i.e. cooling pumps, which only need to operate at full speed some of the time.
Consider parallel pumping systems
Another energy-efficient solution for an installation with differing performance requirements is the use of parallel pumping systems. When the occasional duty requirements are significantly higher than the standard operating conditions, a single pump could be operating far from its BEP for much of the time. By installing a second smaller pump to meet the average system requirements, the larger, higher energy consuming pump would only need to be used when it warrants it.
Limit pipework pressure loss
Specifying the power of a pump needs to account for pressure loss in the system. The length, diameter, layout and internals of a system’s pipework all affect this and should be considered from an energy efficiency perspective. Bends and changes in the size of the pipework should be kept to a minimum, and the diameter should be carefully selected as smaller pipework results in more friction. Corrosion and rust can also increase resistance, resulting in a pressure loss, which means ongoing cleaning and maintenance of pipework is also essential.
Prevent unnecessary use
It might surprise you how often pumps are in operation when they aren’t doing anything. Control systems can be implemented to shut down pumps when not in use, and by using pressure switches, the number of pumps in service can be automatically adjusted as duty requirements vary.
Maintenance
Like any equipment, wear can reduce efficiency. A pump’s energy efficiency can degrade by as much as 10-25% before it’s replaced, which is why routine maintenance is vital. Wearing parts such as wear rings must be regularly inspected and replaced when needed, as leakages mean that the power required to produce the same flow is increased.
So, if you’re concerned about your plant’s energy efficiency and are looking for ways to reduce it, then your pumps are a good place to start.
