Understanding Your Compressed Air System
Improving and maintaining a compressed air system at its peak performance requires analyzing the interaction of the demand and supply sides of the system and the individual components, known as a systems approach. Most compressed air systems use more energy than is needed to support the demand. A complete review of a system and careful corrective measures of a compressed air systems can often result in significant energy savings.
Before you can implement an energy reduction plan for your compressed air system, it is important to be familiar with all aspects of your system, and determine your compressed air system needs. Compressed air system needs depend on the air quality, quantity, and pressure needed by the end uses. Air quality ranges from plant air to breathing air and depends on the dryness needed and allowable contaminant level. Higher air quality typically requires additional equipment, which increases the operational and maintenance costs of the overall system. Over treating air beyond the needed level is costly, and wastes energy. The total air volume requirement is the sum of the average air consumption of each end use tool in the system. The system air demand may vary over time. Analyzing the system load profile, or the compressed air requirement over time is another key component of the overall system analysis.
Understanding Your System
Before initiating any energy efficiency measures, it is important to understand your current system. With the use of simple tools, including a block diagram, and basic understanding of your system you can begin to analyze your system.
- Basic Understanding – Review the basic capabilities of the system, the various modes of operation, supply and demand (including operating schedules), capacity control settings, sequencing (start-up/shutdown, lead/lag), end use, and any other operating conditions.
- Block Diagram – Create a sketch of your entire system from intake to end use. Include all compressors, filters, receivers, air supply lines, and the compressed air end uses. Include all dimensions, the type and capacity of the compressors and any storage tanks.
- Maintenance & Training – Evaluate maintenance procedures and training records.
Analyzing Your System
A compressed air analysis can identify opportunities to save energy and lower operating costs.The analysis should examine the air supply, usage, and interaction between the supply and demand, and investigate all system components individually. Auditors measure input and output, calculate energy consumption, identify problem areas, leaks, evaluate system design, system misuse and inappropriate use, calculate tool system dynamics, and determine the annual operating cost of the system.
The first step in analyzing your system is a Walk-through Evaluation to identify initial opportunities. Additional analysis may be needed based on the size and complexity of the system, including a System Assessment, and a System Audit. In an effort to streamline the system analysis process and provide common methods among auditors, the following guidelines for each level of analysis were developed as part of the Compressed Air Challenge Guidelines for selecting a Compressed Air Service Provider:
- Walk-through Evaluation (1/2 to 2 days) – First step in analyzing your system is a walk-through evaluation, and can be conducted internally by trained staff depending on the system size and needs. This level of analysis provides an overview assessment of the air system to identify initial energy savings, identifies the types, needs, and appropriateness of end use, air quality, pressure, maintenance procedures, and training. If performed by an outside auditor, a written report of the findings and recommendations is provided. A basic assessment can result in lower maintenance costs, and reduce energy use by 25% or more.
- System Assessment (2 to 5 days) – Completed by an external expert, a comprehensive audit builds upon the walk-through assessment and provides more details on your system, defines system dynamics, and can lead to deeper savings. A system assessment includes readings, a pressure profile, and a demand profile to help identify potential problems. This level of additional analysis may be necessary depending on the size and complexity of the system, and if any critical issues were identified during the basic assessment. A written report of findings and solutions is provided, and maintenance and training plans are reviewed.
- System Audit (3 to 10 days) – A system audit provides additional system detail, and is similar to a system assessment. This analysis uses data loggers to further study the dynamics of the system and any problems, and establishes a baseline for comparison. The goal is to align the system properly on the supply and demand side for optimized energy efficiency and savings. A written report of findings and solutions is provided, and maintenance and training plans are reviewed.
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