Pfizer drives down energy costs at Irish site
30 Sep 2010
Ringaskiddy, Republic of Ireland – Pfizer is saving Euro28,000 a year on electricity costs following the installation of motors and variable speed drives (VSDs) on chiller applications at its Ringaskiddy plant in County Cork
The company had identified the plant chillers as prime targets for improving energy efficiency at the Irish plant, which produces bulk pharmaceutical products for shipping to other Pfizer facilities worldwide for finishing and packaging.
The chillers use circulation pumps to pump heat transfer fluid to and from the cold storage tank. Pfizer process engineers asked ABB drives and motors vendor Caltech, in association with EMSA Consultants, to investigate potential energy savings on these drives.
The application included three 45 kW motors and one 37 kW motor, all of them run with soft starters. For best efficiency of the process, the pumps needed to maintain a constant flow rate of 185 m3/hr, but were actually rated for 240 m3/hr. To achieve the optimum flow rate, gate valves were used to throttle the pumps.
“In conjunction with Pfizer Process Engineering we decided that the best way of achieving both the optimum flow and energy saving was to open the valves fully and use variable speed drives to maintain the optimum flow,” said Sean Lee of EMSA.
“We found that we could achieve the desired flow rate by running the motors at 35Hz rather than 50Hz,” he noted.
EMSA used ABB’s Pumpsave energy saving calculation program, which predicted an energy saving of 50% per motor, with cost savings for each motor of around Euro7,200 per year. Based on a running time of 4,360 hours, this would give a payback time of two and a half years.
The full turnkey solution provided by Caltech comprised new VSDs, installation, project management and supervision, drawings, commissioning and full handover to the client. New high efficiency ABB EEx de IE2 motors were also supplied and laser aligned with the pumps.
As well as running the motors at lower speed, VSDs can be controlled by external signalling sources in order to maintain the best flow conditions.
Pfizer hopes to eventually control the drives from the flow meters on the coolant pipelines, giving optimum flow control by matching the speed of the pumps to exact flow demand at all times.
Reliability should also be improved, Lee noting: “As high efficiency motors are less likely to break down and also should not require rewinding or need their bearings replaced for many years. Their cooler running temperature will also mean less mechanical stress.”
Under the Irsh government’s Accelerated Capital Allowance scheme, Pfizer was able to write off 100% of the purchase value of qualifying energy efficient equipment against their profit in the year of purchase.
