Step 3 for Compressed Air Analysis : Improving the Energy Efficiency of Compressed Air System

The following measures can be taken if the specific power of a compressed air system falls below the desired target value:

• Intake conditions: Temperature, humidity, ventilation and absolute pressure affects the efficiency of compressed air generation. High temperature increases operating costs, while inadequate ventilation can reduce efficiency of compressors.
• Compressor selection and control: Different compressors have different efficiency, maintenance and cost that has to be accounted for when designing a compressed air system.

An optimal setup might consists of one variable-speed compressor for peak consumption and two base-load capable compressors. The variable speed compressor can adjusts its motor speed depending on air demand and ensures efficient operation at a load between 40% to 80%.

•        Heat recovery: By utilizing waste heat generated during compression, the efficiency of the system increases and operating costs is reduced.
•        Equipment age, condition and maintenance: Older systems and poor system conditions are often less efficient and can lead to higher operating costs. Regardless of age, regular maintenance and inspection is essential to maintain system efficiency and identify potential problems early on.
  
• Minimizing pressure losses: It is important to size the pressure of the compressed air system accordingly as 1 bar of increased pressure can increase energy consumption by 5 to 7 percent. 

Pressure losses in distribution network due to saturated filters, leaks and inadequate line sizing can create need for higher pressure level at the compressor. A periodic review and subsequent adjustment of the system is important in ensuring efficient operating pressure and save costs.

• Sizing of compressed air tanks and ring lines: Ring lines enables an uniform airflow and pressure distribution due to bi-directional flow. The bi-directional flow increases available airflow by 1.5 times even for the same size pipes. The feeder pipe should be sized at least one pipe size larger than the ring main itself to prevent flow restrictions. 
• Observe compressed air treatment in accordance to ISO 8573-1: Adequate drying and filtering of compressed air is often essential to ensure air quality is met for certain production processes.

In Industries such as food, medical and pharmaceutical, air quality monitoring and requirements is high as compressed air often comes into direct contact with the end products. Failure to maintain the air quality can damage machinery and render product batches contaminated.

• Adsorption dryer for high drying requirements: An adsorption dryer is recommended over refrigerated dryers for very dry compressed air (below -40 degrees dew point. 

Cold regenerating adsorption dryers uses decompression to regenerate the adsorbent, consuming 12% - 20% of dried compressed air. It is suitable for small systems and does not require external energy for regeneration.

Heat regenerating adsorption dryers uses external heat supply to regenerate the adsorbent, and consumes significantly less compressed air. It is suitable for large systems with low air loss.

• Selecting between electric motors and pneumatics for automation: While electric motors are more direct and precise, pneumatics are simply better at handling high loads with longer holding times. As different types of electric motors and pneumatics each have their pros and cons, a combination of them should be chosen appropriately based on application for the system to be most energy and cost efficient.