Emerson Exchange 365

Dinis Ferreira, project manager at Repsol Polimeros, explained how turning to wireless vibration monitoring is helping Repsol identify potential problems with cooling tower fans and pumps. The new automated monitoring solution can alert control room operators to potential failures, enabling maintenance teams to respond quickly.

At the Repsol petrochemicals complex at Sines in Portugal, recovered water from the process is treated and cooled in cooling towers within the utilities unit, before being recirculated to the production plant. This unit is very important for both the production processes and auxiliary systems.

The cooling tower unit has nine cells, which all incorporate motors, fans and gearboxes, and eight water pumps. The cooling tower unit is very flexible, with the number of cells in operation determined by demand. There is also pump redundancy to ensure continued operation. By monitoring vibration, equipment failures can be anticipated and maintenance can be scheduled.

Repsol sought to replace its existing vibration monitoring system at the utilities site. Sensors with BNC connectors were no longer working, not connected, or suffering as a result of corroded cables and junction boxes. In addition, monitoring information wasn’t accessible in the control room.

Pumps and fans within the cooling tower unit were not connected to an online monitoring system. To obtain vibration data, manual readings were taken using portable handheld devices every two weeks, with data analysed offline. Monitoring the fans was particularly difficult, with maintenance teams unable to enter the cells when they were operating.

Repsol decided to install an automated condition monitoring system that would overcome these constraints. Data would be collected within predefined time intervals and provide full spectrum, overall and peak vibration values to help identify potential failures.

“We considered wired and wireless monitoring solutions, and a hybrid of both, but found the cost and time required to install new wiring was high,” said Ferreira. “The cable trench is covered by concrete blocks. Adding new cables would have led to time-consuming installation work.”

Having compared the different systems available, Repsol selected Emerson’s wireless vibration monitoring solution. Project engineering was very easy. Repsol provided the equipment technical documentation, historic data, power supplies and the DCS communications interface. Emerson configured the database, provided advice on locations for the wireless transmitters and handled integration with the third party DCS. During a scheduled shut down, three vibration sensors transmitters were installed on the unit’s eight fans and nine pumps (51 in total) and later 34 transmitters (two per fan/pump) were connected to the sensors.The wireless system was very quick and easy to start up. A wired solution would have required a lot more loop tests.

Data from the wireless transmitters is sent , via a gateway, to the existing DCS, enabling operators in the control room to view overall vibration and PeakVue values from the equipment. Ferreira was keen to point out that all this new data is not critical to the operators, but set-point alarms enable them to be alerted to potential equipment health issues from which they can action the maintenance team to perform inspections and neccessary repairs. Operators are also provided with wireless system health data, alarms for comunication and general system failures, and also low battery life alerts.

Ferreira concluded “We may need to make a few modifications to transmitter locations or add further devices to increase coverage. We also need to correlate historical and new data, and redefine the alarm set points. We are still learning, but we have much more data available now and importantly we now have greater visibility of the health of the cooling tower equipment from within the control room.”