Glass Container Plant Saves $150,000 Yearly by Compressed Air Savings - Part II: Solutions

Continue to our first post in February on Problems and Findings. Here are the solutions taken to improve the compressed air efficiency in this plant, which resulted in $150,000 savings per year!

System Upgraded Features Air Compressor Booster and Controls

To address the critical need to maintain pressure in the low-pressure system at 49 psi – and at the same time – reduce energy waste associated with the compressed air system, Stork installed a single-stage, 200 hp centrifugal booster air compressor rated to deliver up to 2,400 scfm at 84 psi. It also installed a master controller to allow the compressed air system to work together as a single cohesive network using data supplied by airflow meters and controllers.

Additionally, Stork replaced the single-pressure transmitter with two transmitters on the low-pressure system to better measure air pressure and facilitate load sharing and control of the centrifugal machines. On the same system, it also replaced the controllers on each of the centrifugal air compressors with synchronous controllers. The local controllers are equipped with hour counters to measure blow-off of the centrifugal units.

The new master controller monitors the entire compressed air system and determines where the limits are in the different air compressors and automatically adjusts them to efficiently provide air to both processes, while allowing for stable pressure on the low-pressure system. The booster air compressor, meanwhile, plays an equally vital role in system stability and reliability.

System Delivers Stable and Efficient Air Supply

Today, the two centrifugal air compressors on the low-pressure system run at full load to supply air to the glass-blowing process. In addition, the same machines supply air at 49 psi to the booster air compressor. The booster, which also normally operates at full load, increases pressure from 49 psi to 84 psi and supplies air to the high-pressure compressed air system. Doing so allows the plant to meet the primary objective of maintaining at stable pressure of 49 psi when supplying air to the glass blowing operation since any excess air from the centrifugal air compressors is fed to the booster air compressor. Yet, the new configuration also eliminates blow-off of the centrifugal machines on the low-pressure system since excess air is fed to the high-pressure system.

To further ensure a consistent and reliable supply of compressed air at 49 psi to the glass-blowing operation, Stork installed an emergency valve in the piping system between the high-pressure and low-pressure compressed air systems. The valve allows air to flow from the high-pressure system to the low-pressure system if one of the low-pressure centrifugal air compressors fails or is down for service. All the while, the master controller ensures the air supplied to the glass-blowing operation is maintained at 49 psi, even if it’s supplied by the high-pressure system and the functioning centrifugal air compressor on the low-pressure system.

The upgrade also ensures highly efficient operation of the high-pressure compressed air system. As before, the plant operates the two centrifugal air compressors at full load. However, now with supplemental air from the booster air compressor it only normally needs to run two rotary screw air compressors at near capacity to efficiently and reliably supply air to the high-pressure system feeding the plant’s remaining production processes. If the plant requires even more air, the system will automatically add one or more rotary screw air compressors. Doing so eliminates energy waste created in the past by loading and unloading as many as four rotary screw air compressors to meet the needs of the high-pressure system.

Uptime Plus Energy Savings Equal a Win

The recent compressed air system upgrade allowed the global glass bottling and container manufacturing plant to achieve its No. 1 goal: To ensure a reliable and stable supply of compressed air to its glass-blowing operation – which in turn – further strengthens its ability to profitably produce high quality glass bottles and containers with maximum plant uptime. The upgrade has also allowed the plant to meet an equally important goal of saving energy and costs. To date, the plant saves?$150,000 per year on its energy bill thanks to the newly designed system. The project also delivered a payback of less than two years.

The plant manager at the glass container operation said the ability to measure and monitor the? compressed air system was crucial to demonstrating the energy-savings potential to the management team and the value of investing in the system upgrade. Based on the results of the recent compressed air system project, the glass container manufacturer continues working with Stork and VPInstruments to gain additional energy savings through ongoing monitoring and measurement of the compressed air system with an eye toward additional strategies to further optimize system performance.

By Mike Grennier, Compressed Air Best Practices? Magazine