Is Compressed Air Inexpensive Enough To Ignore Measurement?

Air is a vital element of our existence, surrounding us and making life possible. The most remarkable thing about air is that it’s freely available for all living organisms on Earth. However, while air itself may be free, the technologies humans have developed to harness and utilize it for various applications are not.

Over centuries, we’ve innovated ways to use air in medicine, energy generation, climate control, agriculture, aviation, and most notably, industrial operations. One of the most significant developments in industrial use is the air compressor. Air compressors take in atmospheric air and compress it to a higher pressure, which allows it to perform tasks requiring energy beyond what free air can provide. Over time, air compressors have become a cornerstone of industrial infrastructure, revolutionizing production and automation.

Today, air compressors are ubiquitous across industries. From traditional reciprocating compressors to symmetrical screw, and asymmetrical screw compressors to centrifugal, they have evolved to meet growing industrial demands. However, compressing air isn’t free; it requires substantial power, usually drawn from an electric motor or an engine.

When considering the role of electrically powered compressors, especially screw air compressors, which dominate medium to large-scale industries, it becomes clear just how much electrical energy is required to compress air to the desired pressure. Leading brands offer compressors with a specific power range of 5 cfm/kw to 6.7 cfm/kw at 7.0 bar(g) pressure. With typical demands in mid-sized industries ranging from 100 cfm to 3000 cfm, the power consumption needed to meet these demands can be staggering.

In most industrial environments, compressed air requirements fluctuate throughout the day. Unlike continuous process plants, engineering facilities often experience varying demands, leading to compressors frequently cycling between loading and unloading modes. This inconsistency adds to the high cost of generating compressed air. Brands like KAESER COMPRESSORS (Picture 1) are continuously striving to improve the specific power of their machines to address these challenges. For example, the life cycle cost of a typical compressor can be broken down into:

  • 10% capital cost
  • 15% maintenance cost
  • 75% electricity cost

(As shown in Picture 2)

Given that energy consumption makes up the largest portion of operating expenses, it’s clear that businesses must focus on reducing electricity costs. One common approach is to optimize the air distribution system. Over time, many companies have adopted aluminum piping (Picture 3) for compressed air to reduce friction losses. Yet, despite such efforts, varying demand and potential air leaks mean that plants remain at risk of higher power consumption than necessary, which drives up production costs.

Sometimes, in an effort to compensate for leaks or fluctuations in demand, companies add more compressors. However, this often leads to additional problems, such as high velocity in the pipeline. The piping infrastructure, originally designed for a specific capacity, struggles to handle increased air flow. As a result, pressure differentials between the generation and consumption points increase, reducing efficiency and driving up energy costs.

Pressure and Power Relationship
A critical factor in compressor efficiency is the relationship between pressure and power consumption. As a rule of thumb, for every 1 bar(g) increase in pressure, power consumption rises by approximately 6%. Many plants maintain higher-than-necessary pressure levels, either to satisfy machine operators or out of a lack of awareness about how this impacts energy use.

In today’s competitive environment, ignoring these inefficiencies can have a profound impact on a company’s bottom line. Is it wise to remain unaware of these losses? The answer is no. And can these losses be controlled without proper measurement? Again the answer is no.

Many companies remain unaware of the exact losses they are experiencing, the gap between actual demand and generation, and the specific quality of air they truly need. Without accurate data, they rely on estimates, resulting in inconsistent and ineffective energy management practices.

As the saying goes, "If you can’t measure it, you can’t improve it." Optimizing energy consumption in a plant is impossible without measuring key parameters. An Air Audit can help identify and fix inefficiencies once and it is advisable to work with the expert for the best results, but to ensure long-term, consistent improvements, businesses need to invest in world-class measuring instruments like SUTO (Picture 4).

To put things in perspective, even a small 6mm hole in a compressed air system can release between 68 to 104 cfm of air (depending on the finish of the hole) at 7.0 bar(g) pressure (Picture 5). This small leakage alone can cause significant energy losses, demonstrating the critical need for regular monitoring and measurement. This level of loss corresponds to an energy consumption of 11 kW to 17 kW, which translates to an annual cost of approximately ₹528,000 to ₹816,000 for 6,000 hours of operation, assuming an electricity rate of ₹8 per unit.

 

Isn’t this potential savings worth pursuing, considering it can significantly reduce overall product costs? Current industry practices show that air loss through leakages can exceed 15% and may reach as high as 30%. For a system with a capacity of 1,000 cfm, this means that between 150 cfm and 300 cfm could be wasted due to leaks, resulting in astonishing losses.

Investing in instruments that continuously measure parameters like flow rate, pressure, dew point, and power consumption can provide real-time data and insights. With the help of software, these tools can track daily consumption patterns and associated costs of compressed air. Additionally, they can quantify leakages during shutdowns, revealing the true extent of losses and facilitating targeted leak detection and repair.

An investment that is less than your annual losses can enhance your system with high-quality products, yielding multiple benefits. This not only helps maintain your KPIs but also keeps your team focused on achieving a more energy-efficient setup.

In conclusion, investing in proper measurement tools and systems is not an expense but a necessity. It allows companies to maintain efficiency, reduce energy consumption, and prevent unnecessary costs associated with compressed air wastage. By continuously monitoring, plants can ensure they remain competitive in today's energy-conscious market.