The compressor replacement was prompted by necessity – one of the university’s old compressors had a faulty fan unit, which would have been prohibitively expensive to replace. Tom Burton, business development manager at BOGE, explains: “The existing compressors were around 15 years old and the maintenance costs were continuing to rise. Due to the fact that they were inefficient as well as costly to maintain, it made financial sense to look at replacing them.”

 

　　The two compressors that the building uses are set up as a Duty / Standby compressor system with scheduled rotation controlled directly by the on board BOGE controller in the compressors. One is a duty unit, which runs continuously, and the other is a standby machine. If the system demand is higher than the duty machine can cope with, the standby machine will be automatically called for. Using the Duty / Standby system to periodically rotate the compressor, the running hours are evened out making the scheduling of maintenance easy and cost effective. “We were able to measure how much energy was being used by the university compressors and the original ones were running at between 30 and 40 per cent so they were clearly oversized for the current usage demand,” explained Tom.

 

　　“We offered to perform an energy audit in line with ISO standard 11011. This involved a survey of the entire compressed air system and a data logging exercise to measure how much energy was being used by the compressors, as well as a pressure and flow survey to measure how much compressed air was actually being used. Through this process we were able to prove to the customer that significant savings could be made by replacing the compressors, which incorporate many design features and energy saving benefits that were not available 15 years ago when the previous models were supplied.”

 

　　BOGE replaced the two existing SD60 compressors with a pair of BOGE C30FD variable speed units.

 

　　The space-saving BOGE C Series screw compressors are designed for long-term-performance. They offer optimised output volumes with minimal energy consumption, are low in noise emission, and the frequency inverter on the compressor matches energy consumption to compressed air demand, which makes it extremely cost effective to run.

 

　　Their use has helped to dramatically reduce energy bills. The old compressor system at the university had running costs of approximately ?9,700 a year, while the new system is expected to cost less than half this amount every year.

 

　　As part of the new installation, BOGE had to remove the original compressors, which weighed 1.5 tonnes each, without affecting the university’s normal working day.

 

　　Tom says: “We removed one compressor and replaced it with a new one which needed to be up and running before we could remove the second unit. This avoided disruption to the university’s production operations. There is sometimes a need for the two compressors to operate at the same time so we had to get the second new unit installed and working as quickly as possible. The entire operation took just one day.”

 

　　An additional challenge for BOGE was the location of the compressors. The university houses its compressors in a small boiler house, where access and space is very limited. This made removal and replacement difficult. As Tom explains, “The plant room is extremely small, and also below ground, making it difficult to supply the university with high quality air. Our latest design of C30FD compressors are more compact than older models. As there is now more room we are able to duct in better quality ambient air to the compressors – ultimately resulting in better quality compressed air.”

 

　　BOGE has also taken care of after-sales service and support by signing a five-year service contract with the university. This is linked to a “no quibble warranty” for the full five years, with the option of extending the warranty to 10 years.