Industry:
Food & Beverage industry: Grain Milling
Situation:
The grain milling business was powered by a compressed air installation that was aging and had become unreliable. The main mill was powered by two fixed speed compressors. Numerous issues on these compressors resulted in unplanned periods of downtime and lost production.
Task:
Pennine Pneumatic Services Ltd (PPS) was tasked with designing an upgraded compressed air system. To get the main mill back up and running quickly, they installed an Atlas Copco GA75 hire compressor. Once the mill was back in production, the team could survey the site in detail and suggest the most reliable and efficient compressed air solution to suit their requirements.
Action:
An initial survey of the site showed that two of the milling units were powered by four fixed speed compressors. The PPS team advised that they could replace all four fixed speed compressors with one variable speed drive machine to run both milling units. This would improve reliability, but also improve system efficiency. Variable speed drive air compressors can save up to 60% on energy consumption, compared to fixed speed technology.
The next step was a comprehensive energy audit of all four compressors to fully understand the current energy usage as well as the pressure and flow required to efficiently run the site. Following the energy audit, the PPS team ran simulations to demonstrate how the two milling units could run from one variable speed drive compressor.
This simulation demonstrated that the proposed system was predicted to reduce their annual compressed air energy bill by 33%, saving them £98,590 a year in energy and reducing their carbon footprint by 90,787kg per annum.
The PPS team installed a full duty/standby system in their new compressor house, along with a compressed air link line to both mill units.
Following completion, the customer took out a seven-year Guardian service plan with PPS, giving them full warranty, complete peace of mind and fixed servicing costs for the duration of the agreement.
Results:
Reliability
Atlas Copco air compressors are renowned for their reliability, but the new compressed air system also has a full duty/standby set up to allow servicing whilst maintaining full production.
By taking out a service plan, they also further protect the reliability of their system. On average, customers with a compressor service plan in place enjoy 3.5% more production uptime than those without one.
Energy and cost saving
Following the install of the new compressed air system, PPS conducted another energy audit to verify the savings made.
Control
Installing the Atlas Copco centralised controller added to the energy efficiency of the installation, the controller ensures the compressors work within a stable pressure band. On their previous system the compressors had fluctuated between 6.6 bar and 9.5 bar. On their new system the controller keeps the system on a much tighter pressure band between 7.5 and 8 bar. The reduced pressure band means reduced energy consumption, on average 7% of energy is saved per each bar of pressure reduction.
The controller also adds to the increased reliability of the system by distributing the load equally between the duty and standby compressor, equalizing the wear. This means both machines can be maintained on a single visit from a service engineer.
A further benefit of the controller is the easy access to data monitoring and trend analysis.
Short payback
The post install verification data log showed that with the energy savings achieved, the payback period on the capital equipment and installation was 1.5 years.
Fixed costs
By taking out a 7-year service plan with PPS, the customer has been able to fix their servicing costs, helping them avoid price rises and making budgeting easier.