Air Audit : 5 steps to lower production costs
How Can You Benefit from Compressed Air Audits?
An efficient compressed air system is critical to the bottom line of manufacturing facilities in India & around the world. Compressed air accounts for 40% of their total energy costs. There is no denying that not all systems perform as efficiently as they should, and we see this every day. Wrongly sized compressors, outdated technology, Compressed air leakage, excessive pressure drops – the list can go on and on.
Performing a Compressed Air Audit: A Multi-Step Process
The amount of electricity used by air compressors in the United States is estimated to be 10% of all electricity generated in the country. Most of it is wasted. It is estimated that leakage of compressed air accounts for 25-30% of the compressed air use.
As a result, many industrial companies are seeking ways to reduce the energy usage of their compressed air systems. A comprehensive compressed air audit, or “air demand analysis,” is one of the most commonly used methods to accomplish this.
An audit (Airscan) consists of:
Utilization of flow meters in a first-order air installation to analyze demand-side air flow.
– Improvement of flow on the supply side.
-Full energy audit, which includes power consumption and power factor measurements.
-An accurate flow rate, pressure, and power requirement.
-Compressed air quality and dew point.
-Recognizing, quantifying, and costing air leakage.
-Recommendations for correcting air leaks.
-The tracking of air leaks [data management for repeat surveys].
-Maintenance upgrade targeting.
– Flow demand classification and optimization
– Compressed air system distribution
– Possibility verification
– Cost savings analyses for new compressor, new air equipment like air dryers, new spare parts if opted.
– Recommendations and conclusions for potential energy saving.
– Future plans for energy optimization/Savings
The audit of energy consumption is a specialized process; it takes thorough knowledge and expertise in multiple fields to estimate, design, commission and undertake performance monitoring of projects for energy conservation with the following :
-Measurement of the compressed air system accurately.
-Reducing the amount of energy required to produce compressed air for utility
-Trapping of any unused energy.
-Optimum used of energy through recycling.
We enable energy-intensive industries with efficient utility consumption and management, helping with a drastic reduction in electricity bills to make your operations more competitive and increase productivity and overall profitability as a result of compressed air audit service.
-Accurately measuring all the utilities consuming compressed air.
-Reducing energy consumption for compressed air generation.
-Elimination of total wastage.
-Automation & Reduction in operating & maintenance costs.
-Reduction in downtime of equipment.
-Increase in process output.
-Improving the quality and quantity of the production.
-Increasing revenue through decreasing the energy consumption.
-Maintaining and exceeding global industry standards.
Step 1: Conduct a Site Survey before the compressed air energy audit
It is important to list and understand all the equipment & machinery in a compressed air system including compressors, dryer, air receivers , pneumatics tools, electric power tools , energy storage devices, air motor, pneumatic torque wrenches, nut splitters , pneumatic assembly tools , pneumatic calibration systems, Pneumatic breakers, electric assembly systems, pneumatic rock drills and other heavy equipment.
Before installing any measurement devices so that
1) the devices are properly placed, and
2) system dynamics are properly understood.
Auditor should collect all the relevant data like environmental conditions, compressed air system layout, details of all the equipment’s and accessories including air treatment systems, piping’s, storage and controls, production processes should also be documented.
Many auditors will have a general information questionnaire which they will complete to compile the details into one document.
Step 2: Measure and Quantify kW / 100 cfm as part of energy audit
For best results, power, pressure and flow should be measured for a period of at least 10-15 days to determine a accurate plant usage pattern, including nights, weekends and any other downtimes to determine non-productive demands if any.
True power should be measured for energy cost calculations using a accurate power/kilowatt meter by monitoring amperage, voltage, and power factor. Dataloggers should measure data on each compressor at a interval as short as possible (typically 0.5 sec).
Specific power consumed (KW) per cubic feet of air per minute (cfm) can be considered a Key Performance indicator (KPI). This gives us a idea of how efficient a compressed air system is for a manufacturing plant, regardless of the plant output.
Generally this is recommended below 0.21 KW/cfm.
Step 3: Understand the System Dynamics of the compressed air supply
Understand and list down system details to identify opportunities to improve air quality in the compressed air supply along with opportunities to reduce energy usage and wastage for advance energy solutions as part of compressed air audit services.
Step 4: Implement Recommendations to Improve
Most of the time, a energy saving plan after a assessment focus on savings through fixing compressed air leakages and reducing the “inappropriate uses” of compressed air.
One example is the use of a engineered air nozzle instead of a perforated pipe for blow off applications to reduce air demand.
Real energy savings, however, will ONLY be realized if the controls on the air compressors can capitalize on these gains and when appropriate this includes proper use of a variable frequency drive(VFD).
Most of the times, the costs involved with improving compressor controls are never included in the ROI calculations. in most cases many modulating air compressors will be left to consume the same amount of electricity (kW) within broad ranges of compressed air flows (cfm).
Step 5: Verify Performance
A typical Air audit program should also contain a post implementation study by a additional compressed Air auditor after the system is optimized.
Remember, all systems can be further improved, even the ones which have been recently optimized through a Air audit.
This additional audit should verify the compressed Air audit findings and at the same time identify additional areas of improvements.
Conclusion
Compressed air users can ensure better results and ROI when the audit firms utilize a conservative approach based on accurate data of power, flow, pressure, dew points etc over a period long enough to produce a accurate representation on the users usage pattern (typically 10-15 days). Data obtained through the study should be thoroughly analyzed to chalk out best possible energy saving plan for the user. The focus should be on improving KPI pf KW/100 cfm.
A proper system control is a must in implementing a optimization plan. for example a VFD control allowed the compressor to produce compressed air at the lowest acceptable flow/pressure thereby reducing the production cost. For a multi compressor installation, a master controller can be a good solution as it can prioritize compressor use as per demand and turn on or off machine as per the production load.
Regardless of the industry in question (Food and beverage, automotive, power, plastics, power, chemicals, steel, air separation etc.), users will often realize that these air audits will pay for itself through the savings realized due to lower operating cost, improved system reliability and better energy efficiency.
For example, one may realize that their compressed air system has been operating at a much higher pressure (psi) setpoint than required due to air leaks, pressure drops due to downstream accessories, excessive bends in piping’s, compressed air wastage through condensate drains etc. Performing an comprehensive audit of your system can help you identify sources of energy waste like this and planning advance energy solutions for lower operating costs with regular system assessments.
Finally, it should be noted that even though a benefit has been realized by the current exercise, even the best and optimized systems can be further improved for additional savings. A leak detection program along with a full evaluation of the demand side study can be a excellent tool to achieve further desired results. User should along with the auditors, devise a plan of continuous monitoring and improvements.
FAQ :
What is an compressed air audit?
An compressed air audit is an inspection of the Compressed air system in a facility with a aim to make the system more efficient, reliable eliminating “non-appropriate” uses, optimizing the demand as well as delivery side systems and usage of better controls. Join us today to stay connected.
What should I look for in the results of my air audit?
An Air audit in a manufacturing plant should be aimed at increasing system reliability, Decreasing specific power consumption per cfm of air produced and optimizing the demand side as well as supply side systems.
