The starting point
The pump station “D” at the North course of Quinta do Lago has more than 20 years old, so that has suffered from a significant loss of efficiency. Furthermore, the pumps were also incorrectly selected given the required working conditions (they were displaced to the right in their curve). In addition, the discharge piping was insufficient in section, thus generating head losses due to excess water velocity and lengthening the irrigation window of the Lynx system.
Regarding the control system, there was only one VFD for the 4 pumps, and it lacked essential safety and control elements such as air-release valves, a hydropneumatic tanks or flow meters.
The new pump station design
The first step of the design phase was to define the working point of the new pumps (operating pressure and flow rate). It is vital to ascertain these very accurately, and were worked out after gathering information during the initial irrigation audit visit. Subsequently, we have designed a new pump station composed of 3 main pumps plus a fourth jockey pump manufactured by Grundfos. Also, a new discharge piping with a larger section and adapted to existing systems and elements (fertigation and pressure-relief valve).
Regarding the monitoring and control system, we have included a new PLC for the control of the pumps, for which we have assigned an individual VFD, being them integrated with the existing SCADA system that allows for its operational supervision.
Finally, the design comprises new essential control and safety elements: an electromagnetic flowmeter, a new instrumentation piping for pressure gauges and transducers, new gate valves for isolation, two hydropneumatic tanks and a new trifunctional air-release valve.
Our role as irrigation consultants
Our role as consultants during the installation of the new pump station has consisted in the supervision of the works and resolution of incidents throughout the process. This included 2 site visits and remote consultation too.
In the first visit, all the elements of the new pump system were staked out or marked. Also, we held a kick off meeting in which we set up a communication pipeline for an adequate coordination between all the involved parties and we approved the schedule of works. In the second and last visit, we inspected and verified that all elements had been installed correctly, and we also carried out a performance test to verify that the pump station was performing adequately. Finally, the functionalities and integration of the new system in the existing SCADA were checked.
Our service concluded with the production of a document that compiled all the technical documentation (manuals, instructions, warranties, etc.) of the elements of the installation, and a final report summarizing the new operational settings at which the pumps must operate and verifying that the works were carried out satisfactorily.