What to Expect From a Compressed Air System Analysis
To stay competitive, most manufacturing plants are required to continuously increase production while reducing costs. To do so, plants need to identify productivity and quality improvements that lead to lower operating costs. Compressed air audits offer an excellent opportunity to reach these goals with a feasible ROI. While energy cost reduction is usually the driving force behind most system audits, there are many more benefits included:
- Improved plant or process productivity
- Enhanced product quality
- Reduced scrap rates
- Increased system and equipment reliability
- Reduced maintenance costs
Compressed air and vacuum systems are commonly the most inefficient utilities on site. To get one horsepower of work from an air motor requires approximately 30 cfm of compressed air at 90 psig. It takes 6 to 7 HP at the compressor shaft to produce this. (Jan Zuercher, PE, Systems Business Director, Air Science Engineering, Chandler, AZ) Assuming you have a 90% efficient motor, this translates into 7 to 8 HP of electrical power to deliver 1 HP of compressed air. Only 12.5% of the input energy is available for useful work energy on the plant floor.
This conversion efficiency is assuming that all of the equipment is in flawless operating condition. Old equipment, dirty filters, rewound motors, etc., all work together to further reduce system efficiency. The conclusion is that compressed air and vacuum are not free and should be applied with an understanding of the costs involved; however, these costs are usually not identified and are difficult to manage.
The annual operating cost estimations below are based on 8,760 hours of operation per year and $0.05/kWh (maintenance costs included).
- 100 HP = $50,000
- 200 HP = $100,000
- 500 HP = $250,000
- 1000 HP = $500,000
- 3000 HP = $1,500,000
At these rates, the decision to connect an airline to cool a production application can result in a $13,000/yr. operating costs, which would be completely unidentified. Over time, the costs of these kinds of decisions make a system analysis necessary to identify and measure the total savings opportunities.
When choosing an auditing firm to conduct your system analysis, there are a number of things to consider. An experienced company should have no problem providing all of the following information upon your request: References of the individuals performing the work at your facility and actual system analysis reports from your industry to ensure the information is relevant and appears technically grounded. Along with that, a technically complete audit should include the following:
- A simple process flow diagram of the existing system and any proposed mods to it
- An analysis of production applications focused on improving performance and quality
- Recorded pressures throughout the system with a thorough analysis of pressure loss, variation, and corrective measures, especially in production equipment
- Recorded, verifiable power costs with an analysis of compressor and pump performance relative to design
- A detailed action plan with both short term and long term solutions / costs for both
- A return on investment calculation
If you have any questions or concerns regarding compressed air system analysis, please contact C.H. Reed today.