The key to avoiding costly air leaks is a holistic systems approach.
Compressed air is one of the most expensive utilities in any industrial or manufacturing setting. These systems can vary widely in efficiency and are often ignored in favor of more pressing and urgent demands such as pressure levels and air quality. Often times, the efficiency of these systems is impacted by equipment, lack of maintenance or even the system configuration itself. However, there are things that can be done to improve the performance of these costly systems.
1. Monitor the Compressed Air System
First and foremost, a baseline for your compressed air system is crucial. Without a proper picture of typical operating parameters, improvements cannot be successfully identified or implemented. Measurements should be taken on key parameters such as pressure, power, flow and dew point. Once collected, these factors can be monitored to note deviations from the normal operating performance and the success of corrections to these identified issues can be confirmed.
2. Implement Compressed Air Leak Detection & Repair Program
Studies have shown that anywhere from 20-40% of compressed air fails to make it to its intended destination. Having a plan in place to detect and repair leaks can recover a large amount of utility costs. The simplest form of detection can simply be staff using their ears to listen for leaks and tighten up piping appropriately. There are also ultrasonic leak detection products that can be utilized for more precise detection. Even the manual detection process and corresponding corrections can save 10-15% on a site’s energy bill.
3. Check Component Pressure Loss
It’s critical to keep an eye on how much pressure differential exists between the piping drop and the compressed air’s end use. Often times, a large pressure differential will occur in the last 30 feet of pipe as this is often the home of undersized filters, regulators, connectors and hoses-all elements that can contribute significantly to a sizable differential. Why is this problematic? When there is an extreme differential in pressured in this section of the compressed air system, the discharge pressure at the air compressor itself must rise to compensate. This increases power costs. Giving proper consideration to the size and care of these components can reduce wear on this equipment, minimize leaks and reduce energy costs.
4. Modify Plant Piping
Many plants grow overtime, increasing compressed air demands that are too much for the original piping to accommodate. When this happens, the undersized compressed air piping can cause flow issues that force the compressor discharge pressure to increase to compensate. Continually monitoring compressed air piping differential pressures will identify whether this becomes a costly problem that can be resolved with piping configuration and sizing modifications.
5. Adjust Compressed Air Pressure
Often times, the compressor discharge pressure is higher than it needs to be-the higher the pressure, the more energy it consumes. There can be several reasons for this but often the pressure is set to the compressor rating without consideration given to the plant’s actual pressure needs. By ensuring equipment is operating to actual needs instead of manufacturer specs, facilities can reduce this excess pressure that causes compressors to consume more energy than necessary.
6. Optimize Ancillary Compressed Air Components
The air from a compressor must be conditioned so that it doesn’t contaminate other equipment with oil residue or moisture. This can be an energy intensive process depending on the type of air driers being used to filter and remove contaminants from the compressed air. Selecting more efficient air driers that reduce power consumption in this process, whether by efficient design, low or no purge flow or lower pressure differential, can add up to big operational savings. Every psi counts.
7. Efficient Compressor Controls
Most compressors and air driers are not being controlled efficiently. With regard to individual compressor controls, there are various modes of operation with corresponding levels of efficiency. Inlet modulation mode, for example, is the least efficient way to control any compressor that is running at part load but may be acceptable if the compressor is always at or near full load. Conversely, the variable speed mode is the most efficient way of controlling compressors at part loads but may not be the most efficient at full loads. Preparation and planning needs to go into setting up and coordinating multiple compressor systems to ensure the system is operating at an efficient level.
To assist with this, consider compressed air control systems to ensure the correct compressors are running at a given time, equipment is running smoothly, and that the system pressure is held within specified limits.
8. Utility Incentives
Many utilities support compressed air improvements and provide financial incentives for initiatives that reduce energy costs. Most will at least fund an audit to identify areas for improvement and many will fund a significant portion of the investment needed to achieve these improvements.