Eight Practical Levers to Cut a Compressed-Air Energy Bill

Compressed-air systems are the lifeblood of many industrial operations, but they can also be a significant drain on energy resources. Plant engineers, maintenance managers, and energy managers are constantly seeking ways to optimise these systems and reduce energy costs. By focusing on eight practical levers, significant savings can be achieved without major capital investments.

Identifying and Repairing Leaks

Leaks are one of the most common and costly issues in compressed-air systems. In most plants, leaks typically account for 20% to 30% of the total compressed-air demand. Regularly identifying and repairing these leaks can result in substantial energy savings. To effectively manage leaks, plant managers should:

• Conduct regular leak surveys using ultrasonic detectors.
• Prioritise repairs based on the size and location of the leaks.
• Implement a leak management program to ensure ongoing monitoring and maintenance.

Reducing System Pressure

Another key lever to reduce energy consumption is to lower the system pressure. Every 0.1 bar reduction in system pressure can save approximately 1% of the compressor's energy consumption. However, it is crucial to ensure that the pressure reduction does not compromise the performance of the equipment using compressed air. To achieve this, consider:

• Reviewing the pressure requirements of all equipment and processes.
• Adjusting the compressor's pressure setpoint to the minimum required level.
• Using pressure regulators to maintain consistent pressure at the point of use.

Optimising Air Storage

Proper air storage can help stabilize the compressed-air system and reduce the frequency of compressor startups and shutdowns. This can lead to significant energy savings. To optimise air storage, consider:

• Installing or increasing the size of air receivers.
• Ensuring that the air receivers are properly sized for the system's peak demand.
• Using pressure switches to control the compressor's operation based on the air receiver's pressure.

Utilising Variable Speed Drives (VSD)

Variable speed drives (VSDs) allow compressors to adjust their output based on the actual demand for compressed air. This can significantly reduce energy consumption compared to fixed-speed compressors. To implement VSDs effectively, consider:

• Replacing fixed-speed compressors with VSD-equipped compressors.
• Monitoring the system's demand and adjusting the VSD settings accordingly.
• Using VSDs in conjunction with air storage to further stabilize the system.

Implementing Heat Recovery

Compressed-air systems generate a significant amount of heat, which can be recovered and used for other purposes. This can help offset the energy costs of the compressed-air system. To implement heat recovery, consider:

• Installing heat exchangers on the compressor discharge lines.
• Using the recovered heat for space heating, water heating, or other thermal processes.
• Regularly maintaining the heat exchangers to ensure optimal performance.

Right-Sizing Dry-Air Quality

Many compressed-air systems operate with higher air quality than necessary, which increases energy consumption. By right-sizing the air quality to the actual requirements of the processes, significant energy savings can be achieved. To right-size dry-air quality, consider:

• Identifying the specific air quality requirements for each process.
• Using air dryers and filters that are appropriately sized for the actual demand.
• Regularly monitoring and adjusting the air quality settings based on the process requirements.

Sequencing Compressors

In multi-compressor systems, sequencing the compressors can help optimise energy consumption. By starting and stopping compressors based on the actual demand, the system can operate more efficiently. To sequence compressors effectively, consider:

• Using a central controller to manage the compressor sequence.
• Programming the controller to start and stop compressors based on the system's demand.
• Regularly monitoring the system's performance and adjusting the sequence as needed.

Implementing Monitoring and Control Systems

Effective monitoring and control systems can help identify inefficiencies and optimise the compressed-air system. By continuously monitoring the system's performance and making adjustments as needed, significant energy savings can be achieved. To implement monitoring and control systems, consider:

• Installing sensors to monitor key parameters such as pressure, flow, and temperature.
• Using a central control system to collect and analyse the data.
• Implementing alerts and notifications to promptly address any issues that arise.

Key Takeaway

By focusing on these eight practical levers, plant managers can significantly reduce the energy consumption of their compressed-air systems. Regular maintenance, careful monitoring, and strategic adjustments can lead to substantial savings and improved system performance.

Planning a compressed-air upgrade? Talk to SIND's engineers.