To think that so many pumps operating today were built up to 50 years ago… It shows you what happened in the good ole days when it seemed we were more skilled at matching operating demands to the pump selected and the pump designers were good too.
Pumping applications still account for more than 20% of the global electric motor energy consumption – so there is a real opportunity for plant owners and managers to increase the efficiency of their older equipment. And because the equipment is older it is getting harder and harder to use it efficiently.
Systems Change Over Time
Operating conditions evolve over time. When this happens pumping application demands also change. You can see changes in flow, media characteristics or duty… Just because a pump can operate on the outer edges of the system curve does not mean it should. Performance and reliability can be reduced.
Dialing up/back pump flows has consequences. To know in advance what those consequences will be you need to measure the operating conditions to calculate the point at which the pump will operate on the system curve.
Then you need to compare these with the original documentation about the pumps performance – are you exceeding maximum flow? Are you above the net positive suction head required?
Let’s imagine a multistage boiler pump – it has suffered severe damage… The suction side seal, several impellers, sleeves and even stationary components had been destroyed.
This pump has almost certainly been operated at or near shutoff flow. The water in there has turned to steam because there was insufficient flow to discharge the heat generated by the pump.
Inefficient Pump Operations
The most likely cause of the problem is the plant has changed its need to steam over time and scaled back their water input to the point where this pump can no longer pump anywhere near its best efficiency point.
In some cases it might be possible to increase the system flow so that the pump can remain in service – this is the most likely outcome. However, in other cases some retrofitting of either the pump or the system might be required so that you can operate your pump within its specifications. In other cases a new pump may be the best option to reduce energy consumption while meeting your needs now and in the future.
If you are having trouble with a pump or even a pumping system call the team at Pye Barker on 404-363-6000 or drop us a line firstname.lastname@example.org we’ll do what we can to help you out.