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- Measure it – A big indicator of the efficiency and effectiveness of your compressed air system comes in the form of measurement – and specifically, taking a baseline so that you can understand where you are and how well your system is meeting your organization’s needs. This will allow you to understand how effectively and accurately pressure and flow are being produced and how much it is costing you. Assessing the quality of the compressed air also is important, as is measuring the level of waste generated through leakage and inappropriate use. Most people have no idea how their key performance parameters compare with optimum performance. Call in a good compressed air system expert to help you with this.
- Reduce the waste – Your efforts in optimizing your compressor control will be wasted if your leakage levels are so high that you lose half of your compressed air before it gets to your end users. And once it’s at the final compressed air device, the compressed air may be used inappropriately where some other source of energy could better provide energy for the work. This step takes some manpower and perhaps the use of an ultrasonic leak detector, but waste reduction has a big impact overall, especially on well-controlled compressed air systems.
- Manage it – Often, the second biggest impact on compressed air system cost comes from properly managing the system through good compressor control. This requires taking the information from step one and analyzing it. From this data, a control strategy is developed that can improve pressure, yet reduce energy cost. This may involve things as simple as adjusting control settings, or more complex solutions like adding large storage volume, installing central compressor controllers, or even replacing a compressor or two.
- Take action: Fix the problems – So often, organizations have access to a study that has been done on compressed air systems, but no actions. Know that thousands of other compressed air systems have been improved in the past years, often with huge results of 30% to 50% reductions. It is not unheard of to save 80% or so in some extreme cases. Some of these systems may have been owned by your competitors. Is money the problem? Very often, compressed air improvement projects pay for themselves in less than one to three years. That’s a good return on your investment! And part of the project costs may be funded by utility incentives. But it is important to take action to capture these savings today.
- Educate air users - train your people – Knowledge is power when it comes to compressed air optimization. Studies have shown that when factory workers and managers attend awareness training about optimizing compressed air systems, the information gained usually yields fruitful projects that save energy and improve the compressed air system in general. One key piece of information is awareness of the typical high cost of compressed air and what to do about it. Search for compressed air efficiency training in your area through today!
Controlling multiple rotary screw compressors gets more complicated as the number of system compressors increases. In systems with three compressors or fewer, adequate control can often be accomplished with coordinated pressure bands and load/unload and/or variable drive (VSD or VFD) compressor control.
- Compressed air leakage of 30 – 40 percent is not uncommon. Carry out periodic leak tests to estimate the quantity of leakage.
- Reduce compressor delivery pressure, wherever possible, to save energy.
- Ensure air intake to compressor is not warm and humid by locating compressors in well-ventilated area or by drawing cold air from outside. Every 4°C rise in air inlet temperature will increase power consumption by 1 percent.
- Clean air-inlet filters regularly. Compressor efficiency will be reduced by 2 percent for every 250 mm WC pressure drop across the filter.
- Keep compressor valves in good condition by removing and inspecting once every six months. Worn-out valves can reduce compressor efficiency by as much as 50 percent.
- Install manometers/PTs across the filter and monitor the pressure drop as a guide to replacement of element.
- Minimize low-load compressor operation; if air demand is less than 50 percent of compressor capacity, consider change over to a smaller compressor or reduce compressor speed appropriately (by reducing motor pulley size) in case of belt driven compressors or even replace gear-set.
- Consider the use of regenerative air dryers, which uses the heat of compressed air to remove moisture.
- Fouled inter-coolers reduce compressor efficiency and cause more water condensation in air receivers and distribution lines resulting in increased corrosion. Periodic cleaning of intercoolers must be ensured.
- Compressor free air delivery test (FAD) must be done periodically to check the present operating capacity against its design capacity and corrective steps must be taken if required.
- If more than one compressor is feeding to a common header, compressors must be operated in such a way that only one small compressor should handle the load variations whereas other compressors will operate at full load.
- The possibility of heat recovery from hot compressed air to generate hot air or water for process application must be economically analyzed in case of large compressors.
- Consideration should be given to two-stage or multistage compressor as it consumes less power for the same air output than a single stage compressor.
- If pressure requirements for processes are widely different (e.g. 3 bar to 7 or 10 bar), it is advisable to have two separate compressed air systems.
- Provide extra air receivers at points of high cyclic-air demand which permits operation without extra compressor capacity.
- Retrofit with variable speed drives in big compressors, say over 100 kW, to eliminate the `unloaded’ running condition altogether.
- Keep the minimum possible pressure range between load and unload pressure settings.
- Automatic timer controlled drain traps wastes compressed air every time the valve opens. So frequency of drainage should be optimized.
- Check air compressor logs regularly for abnormal readings, especially motor current cooling water flow and temperature, inter stage and discharge pressures and temperatures and compressor load-cycle.
- Install equipment interlocked solenoid cut-off valves in the air system so that air supply to a machine can be switched off when not in use.
- Present energy prices justify liberal designs of pipeline sizes to reduce pressure drops. Compressed air piping layout should be made preferably as a ring main to provide desired pressures for all users.
- A smaller dedicated compressor can be installed at load point, located far off from the central compressor house, instead of supplying air through lengthy pipelines.
- All pneumatic equipment should be properly lubricated, which will reduce friction, prevent wear of seals and other rubber parts thus preventing energy wastage due to excessive air consumption or leakage.
- Misuse of compressed air such as for body cleaning, agitation, general floor cleaning, and other similar applications must be discouraged in order to save compressed air and energy.
- Pneumatic equipment should not be operated above the recommended operating pressure as this not only wastes energy bus can also lead to excessive wear of equipment’s components which leads to further energy wastage.
- Pneumatic transport can be replaced by mechanical system as the former consumed about 8 times more energy. Highest possibility of energy savings is by reducing compressed air use.
- Pneumatic tools such as drill and grinders consume about 20 times more energy than motor driven tools. Hence they have to be used efficiently. Wherever possible, they should be replaced with electrically operated tools.
- Where possible welding is a good practice and should be preferred over threaded connections.
- On account of high pressure drop, ball or plug or gate valves are preferable over globe valves in compressed air lines.
