This is the method which also guarantee you minimum energy saving achievable in pumps. The actual savings will be higher always depending on various other factors. I used this method recently & saved ~15% power consumption in CW pumps i.e. ~600 kW out of 4000 kW load resulting in huge savings with a payback of merely 4 months.
- First of all make a list of all pumps with design flow & head in two different columns in an Excel sheet. Say column A with flow & Column B with head
- Now measure the power consumption in the field & put it in Column C.
- Now in Column D put calculated power consumption with efficiency available for new pump & high efficiency motors.
- New pump efficiency for CW flow of more than 300 M3/hr at 40 m head can be considered ~80% which can go as high as 85% for bigger size pumps beyond 1000 M3/hr.
- High efficiency motor can have efficiency in the range of 94%+for motors of >100 kW, which can be 96%+ for bigger motors >300 kW
- After getting the final figure of power consumption for a new pump, you can put the saving potential in the next column E.
- Put the investment required for motor & pump in next column F judiciously (you can ask me for indian cost roughly) Or get it from some vendor
- Put payback or ROI in the next column G
You are through now. Suggest the replacement to your management in a nice presentable format for approval. Mind it that this method gives you minimum guaranteed savings from these pumps because,
- This method is not considering any flow & head measurement therefore, you get minimum savings in case your pump is not delivering the design or considered flow. Anyway it can not deliver more than design without compromising on head.
- The chances of errors are very less as you are measuring only power which is measured reliably & more accurately.
- You do not have to deal with plant people convincing them about the accuracy of flow measurement. Because flow is the most troublesome area where mostly people do not believe (Or they dont want to) about large drops.
- This gives you option of selecting the latest & most efficient equipment in the market.
Don't you believe on this?
I Said......I have already saved 15% power i.e. ~600 kW.