Case Studies

Thermancy works closely with its clients as well as its distributors, helping them to reduce pumping energy costs. The case studies shown below are from recent work we completed for clients.

Case Study 1 – Removing Throttling

Background

There are 5 pumps at this station. The fixed speed pumps 1,2&3 have a duty of 6.8m3/min at 60m, and variable speed pumps 4&5 have a duty of 6.94m3/min at 60m. Pump Monitoring equipment is fitted to all the pumps.

The normal running combination is for one fixed speed pump 1-3 to be running with one variable speed pump 4-5. The delivery valves of the fixed speed pumps need to be throttled for these pumps to run, and the variable speed pumps are run at a set frequency of approximately 56Hz. An additional pump is run if required.

Case Study 1

Conclusion

The head/flow performance of the pumps is too high for the pumping system; the fixed speed pumps require throttling to be able to be run, and the variable speed pumps require running at reduced speed.

It may be possible to select a smaller impeller for the fixed speed pumps 1-3 to match the system curve. If not, these pumps should be replaced with lower head pump units.

The power saving for this pumping station by avoiding throttling the fixed speed pumps 1-3 was approximately 8%.

 

Savings Achieved

8%
Avoiding Throttling

Case Study 2 – Pump Scheduling

Background

There are 10 pumps at this station. The fixed speed pumps 1 to 9 have a duty of 4584 m3/hr at 65m, and pump 10 has a duty of 6000m3/hr at 65m. The pump monitoring equipment is fitted to all the pumps.

The normal running combination is for 2 pumps to run during the day, 3 in the evening and 4 over night.

Case Study 2

Conclusion

The logged data from the Pump Monitors identified the most efficient combinations of 2, 3 & 4 pumps to run, and by running these combinations, respective power consumption savings of 5.0, 4.3, & 3.2% were achieved.

At present, the pumps are not well matched to the pump system. By trimming the impellers of the pumps, a further power cost saving of 18% can be achieved.

Savings Achieved

5%
by running 2 Pumps
4.3%
by running 3 Pumps
3.2%
by running 4 Pumps
18%
impeller trimming

Case Study 3 – Impeller Trimming

Background

There are 5 pumps at this station. The fixed speed pumps 1,2&3 have a duty of 400m3/h at 70m, and variable speed pumps 4&5 have a duty of 420m3/h at 70m. Pump Monitoring equipment is fitted to all the pumps.

The normal running combination is for one variable speed pump 4 or 5 to be running. If more flow is required, a fixed speed pump is turned on.

Impeller Trimming

Conclusion

The head/flow performance of the pumps is too high for the pumping system; the fixed speed pumps require throttling to be able to be run, and the variable speed pumps require running at reduced speed. The variable speed pumps were also throttled.

The power saving for this pumping station by avoiding throttling the pumps and trimming the impeller of the fixed speed pumps is approximately 10%.

Download the case study (pdf 135KB)

Pump Impeller Trim Reduces Pumping Energy Costs by 10 percent

 

Savings Achieved

10%
Avoiding Throttling

Verification

Also, just as it has been used to identify these opportunities for power cost saving, the installed pump performance monitoring equipment can be used to verify the savings once the improvement measures have been implemented.