Eliminate idle time and minimize pressure fluctuations: These were the project objectives set out by Airbus for upgrading the central compressed air supply at its Hamburg plant. A GA 160W VSD variable-speed, oil-injected screw compressor and the ES 130 V master control system from Atlas Copco are key components in the new compressed air concept.
Compressor room at Airbus
The production processes at the Airbus plant in Hamburg, Germany, rely on a constant supply of compressed air. Approximately 3,000 technicians work on the assembly line, in the paint shop, and on the interior finishing line, using almost exclusively pneumatic tools, which consume an average of 50 to 70 m3 of compressed air per minute. Since the compressed air consumption drops considerably during breaks, the supply undergoes significant fluctuations in demand.
A wide pressure band and considerable idle time
In the past, the compressed air required for production was provided by four screw compressors. Depending on requirements, one or more of the machines were networked, creating a relatively wide pressure band of 6.6 to 7.6 bar. Combined with a full load/no load control concept, this set-up led to a significant amount of idle time because the compressors were not able to start up more than three times per hour.
As a result, they would sometimes be idle for up to 50 minutes per hour, while still using at least 20% motor power. It was clear to Airbus that the amount of energy consumed during the idle time was far too high and the decision was made to redesign the compressed air supply at the plant.
Variable-speed compressor covers peak load
The centerpiece of the new compressed air system is a GA 160W VSD variable-speed, oil-injected screw compressor from Atlas Copco, which has been combined with a GA 110W compressor to replace one of the old compressors. The three existing compressors have been integrated into the new concept.
A CAN bus module allows each compressor to communicate with the ES 130 V master control system recently acquired from Atlas Copco. Based on the volume of compressed air required, the controller selects the appropriate base load machines and ensures that the variable-speed compressor, which covers the peak load, is in the optimum range. Today, the plant is supplied with compressed air at a continuous pressure of 7.2 bar with a maximum fluctuation range of 0.1 bar. No-load losses have been virtually eliminated, allowing the energy balance to be improved.
Alongside the two GA compressors, the new compressed air system features two new FD 750W VSD variable-speed refrigerant dryers from Atlas Copco. The refrigerant dryers are connected downstream from the GA compressors and ensure that the compressed air enters the piping network at a dew point of 2 to 3°C. The existing compressors now also feature refrigerant dryers, which dry and clean the air following compression.
Heat recovery offers additional efficiency gains
Efficiency at the plant is further increased by Airbus’s own heat recovery concept, which passes the waste heat from the compressors through a water cooling system and heat exchanger before using it to preheat the combustion air in the heating plant. The two new water-cooled compressors from Atlas Copco were easily integrated into this concept.