DDD helps avoiding water loss as well as energy and CO2 waste

The as-is situation 

Water supply plant at Via Bassa, San Giovanni in Persiceto, is managed by Gruppo HERA and feeds two aqueduct branches, serving two different parts of the city, connected to each other. The existing pumping system was made by 4 normalised-axial-suction Grundfos pumps NB 100-200/192 driven by 45 kW electrical motors (2 poles, IE2 efficiency class). 4 VACON inverters connected to the PLC were controlling pumps speed in order to guarantee a discharge set pressure of 2.6 bar.

HERA‘S target was:

  • to stabilise water network pressure
  • to supply 24/7 the right pressure at the critical points
  • to comply with the agreement signed with the municipality

The target was even more crucial considering that the aqueduct supplies water to an high-water-demand hospital.

The Gruppo HERA

HERA (more than 9,000 employees) manages several water networks with a total length of 35,359 km. Every year it supplies 289.3 million m³ of potable water to 3.6 million citizens in 330 cities across 4 Italian regions (Emilia-Romagna, Marche, Veneto and Friuli-Venezia-Giulia). Focused on innovation and new solutions for the water supply service, and always contributing to the environmental sustainability, HERA has a strong partnership with Grundfos not only for the new pumps, but also for the design and deployment of tailormade control systems and solutions in the water networks applications.

The solution

San Giovanni in Persiceto’s project has been handled by Grundfos across several steps. 

DDD: The Demand Driven Distribution technology has been presented to HERA.

Audit: The Grundfos Service team has performed a DDD audit on the existing pumping system. DDD audit has also included pressure monitoring at the network’s critical points, by using remote self-powered datalogger installed with the support of HERA.

Analysis: Data analysis allowed to have a clear picture of the network and to estimate the potential benefits by introducing the DDD control logic and by changing to a new and more efficient pumping system made by 4 normalised-axial-suction Grundfos pumps NB 100-315/334 driven by 30 kW electrical motors (4 poles, IE4 efficiency class).

Report: The outcome of the analysis has been presented to HERA with a report showing (1) the estimated stabilisation and reduction of the pressure at the critical points, (2) the reduction of water losses and piping breaks, (3) a huge energy saving in line with the targets.

HERA proceeded as suggested by Grundfos introducing the DDD and renewing the pumping system. Hardware has been kept as it was (inverter, PLC, remote control), with the integration of the Control DDD for the optimised control of the pumps operation.

The result

Achieved results have been assessed with an ex-post audit (post DDD audit) and they are fully aligned with the estimation made during the DDD audit. Thanks to the DDD, HERA has been able to stabilise and reduce the pressure at the most critical point CP1 guaranteeing an higher comfort to the customers and a lower stress to the whole water network. Also second branch has gained a pressure reduction and stabilisation (see graphs).

Numbers to highlight, thanks to the DDD:

  • 2.3 bar at the critical point CP1 (instead of the previous 2.7 - 3 bar)
  • 1.9 - 2.3 bar of pumping system discharge pressure (instead of the previous 2.6 bar)
  • 110,000 kWh/year estimated energy saving
  • 58,000 m³ of water loss avoided
  • 36 t of CO2 saved
  • 0.09 kWh/m³ specific energy (instead of the previous 0.13 kWh/m³)
  • 1 year and 5 months of payback time

The Grundfos DDD

Demand Driven Distribution (DDD) is a solution patented by Grundfos for the intelligent management of the pumping systems, capable to adapt to the actual requirements of the water networks.

By regulating automatically the discharge pressure set point basing on the water flow, the DDD stabilises the pressure at all points along the whole network. The connection with one or more remote self-powered dataloggers installed at the critical points allows a daily update of the parameters of the algorithm behind the DDD.

Continuous monitoring also allows to get notified in case of sudden breaks or unexpected issues in the network. Customers that decided to install DDD keep providing positive feedback to Grundfos, certifying the success of the solution. Also the increasing demand for new DDD audits and the overall interest around the solution are an important appreciation and a boost for the future. 

Key benefits are:

  • Stabilisation and reduction of the network pressures
  • Reduction of the water losses, avoidance of the water hammers and piping breaks
  • Comfort for the utilities
  • Overall higher energy efficiency