The energy bill for compressed air at a UK car [ manufacturing plant was around
The second method was to connect a retrofit variable speed drive to one compressor and integrate it into the control system. This was installed later on and is set to reduce the energy costs by a further 8% by eliminating in excess of 90% off-load running and to effectively maintain a narrower pressure band of between 7.9 and 8.1 bar The drive enables the system controller to run six of the compressors at their most efficient speed and use the VSD controlled unit to finely balance system pressure. Off-load running refers to compressors running unnecessarily to maintain system pressure when there is no actual demand.
Monitoring is a key element
As compressed air is an integral part of the whole 24/7 production cycle, the challenge for the compressed air service supplier is to achieve an uninterrupted air supply.The EnergAir system has helped achieve this using the EnergAir Alert' automatic early warning system combined with realtime monitoring and remote interrogation. The monitoring facilities integrated into the system include: energy usage, system efficiency, compressor status, compressor bearing condition, compressor water coolant temperature, dew point analysis, room temperature, air filter status and air discharge pressure to the system.
Monitoring to this depth provides both a highly accurate measurement of system performance over time and the detailed real-time feedback needed to activate EnergAir's Alert software.Threshold levels, dictated by experience and system demands are set in the Alert software for all relevant operating parameters. A time or frequency buffer is set and if any part of the system runs over the threshold, an alarm is tripped. Alarms are categorised due to their seriousness and an automatic warning is generated. Messages are tiered and relayed via modem to faxes, emails or text messages. Response thresholds are set and in a potential emergency the system will follow a sequenced contact pattern until it gets a response 24/7.
The Alert system then allows Oscott to interrogate the EnergAir system, either prompted by an Alert message or as a routine check from its local office and react accordingly This has reduced the number of callouts and improved response times, because the supplier is aware of a potential problem before it has a chance to develop and is fully briefed before an onsite visit is made.. MS
