Take a SMART approach with compressed air leaks
Setting specific objectives
Every successful project starts by setting specific expectations and desired outcomes. Defining specific goals at the beginning of the leak management process will help ensure other aspects of the project deliver desired results. To achieve energy conservation and monetary savings associated with fixing leaks, it is imperative that the project specifically state the desired outcome.
If leadership assigns a formal goal to reduce energy consumption, the project scope must state “to reduce a targeted amount of air compressor energy consumption by repairing compressed air leaks.”
Measuring the impact on energy savings
Accurately defining how progress is measured has a significant impact on energy conservation and final results. Most efforts to manage or minimize compressed air leaks fail or deliver marginal results because of insufficient details regarding how progress and results will be measured and documented up front.
Depending on the significance of the compressed air savings relative to the facility’s total monthly energy consumption, the most basic measurement is based on the change in the monthly electrical bill. For many systems, energy savings from repaired leaks are only a fraction of a percent of total facility power, making it difficult to pinpoint a change in energy consumption directly attributed to leaks.
Conducting a leak assessment that provides a prioritized leak list, sorted by leak volume, introduces another level of accuracy. Using the prioritized list, maintenance personnel can focus on the larger, most accessible leaks first, and then work their way down the list until achieving the desired reduction in air volume. This facilitates more efficient use of maintenance personnel since they do not waste time hunting all leaks.
A leak assessment process that incorporates a before-and-after measurement of repaired leaks validates that leaks are repaired properly and compressed air demand is reduced.
The level of accuracy relative to hard savings increases with the measurement detail. Since the objective is energy conservation, another option is to measure compressor operation before and after leak repair. This can be accomplished with online/offline compressors by simply recording loaded, unloaded, and running hours per week for several weeks before and after repairing leaks. A reduction in loaded hours represents energy conserved. To improve the accuracy of energy reduction results, conduct a non-intrusive compressor assessment and summary of compressed air and energy consumption before and after leak repair. Many organizations provide simple compressor energy assessments for a reasonable cost or include it within their contractual service agreements.
Ideally, leak repair should be part of an ongoing effort to sustain and improve compressed air system efficiency, not a periodic event. To maintain operating efficiency, a facility must have sufficient instrumentation and trended data to establish a baseline associated with compressed air demand and energy consumption.
Expectations can be defined based on established performance metrics or performance indicators. This level of detail includes kW, flow, and pressure instrumentation for the compressed air system, and the ability to summarize and analyze system performance.
Some systems trend flow data at the sub-header or production cell level, so total leak volumes can be pinpointed for specific areas. This level of detail is limited to facilities with resources committed to operational excellence and best-in-class performance. For most systems, instrumentation is limited to hours and pressure from the compressor control panel and an assortment of pressure gauges of varying quality. A plethora of measurement methods can be applied with level of accuracy being a function of complexity and cost.
It is important to note that a reduction in compressed air demand can only influence compressed air power consumption. The largest error made when attacking leaks is assuming that a system consumes 0.18kW/scfm and every 100 scfm of leaks repaired will reduce power 18kW. Depending on the installed compressors and how they operate as a system relative to production demands, actual savings can be very different. There are many examples where savings can vary from several times greater to no savings at all. In some operating conditions, repairing leaks can actually increase energy consumption. This is a more complex issue potentially presented in a future article.
Armed with an increased understanding of how compressed air demand reduction and saving energy are related, repairing compressed air leaks can be part of an inferred energy savings project or an investment grade project. If there is no requirement to validate savings or directly impact the budget, then inferred savings is the easiest project.
Many large corporations are only looking at rolling averages based on total annual energy across several hundred facilities. For these situations, simplicity and cost to execute are more important than validated results. This is a reasonable approach for projects that do not require capital expenditure and are expected to deliver small returns relative to total consumption. If this is the case, the easiest measurement plan is based on number of leaks repaired.
Leveraging the statistical data provided and a simple 0.18kW/scfm conversion, every leaking FRL repaired represents a 3 scfm reduction and an annual savings of 540 kWh/1,000 hours of operation. Using an electrical rate of $0.10/kWh and a 6,000-hour year, each FRL leak repair infers a $324 savings. A measurement plan for this project could be a simple list indicating location, type of leak repaired, and how the repair was made.
Agreeing on goals
It is essential to get everyone who is involved with a leak repair project—and their direct supervisors and other company leaders—in agreement with the expectations and measurement process, in order for the project to be successful.
Many repair efforts never go beyond the leak identification stage because maintenance leaders are not accountable for—or aligned with—the project goals. Consequently, they will reallocate maintenance resources for other issues, potentially abandoning leak repair expectations over time. It is just as important to be aligned with production leaders, since many leaks require access to production areas and may require downtime to repair.
Identifying realistic goals
Engaging team members who are familiar with the facility and knowledgeable about its compressed air use will help to ensure set goals are realistic. Consulting with someone knowledgeable about the installed compressors and their control configurations will help to determine if energy savings goals and measurement plans are realistic.
Setting time-bound repair goals
Without setting project milestones and completion dates, it is easy for resources to get engaged and committed to other projects. Fixing leaks is not exciting, and any excuse is a good enough reason to put the task aside. Pick a date, allocate the time, and get it done.
Addressing leaks during routine maintenance activities
There is no magic solution to rid an industrial facility of compressed air leaks, but an increased understanding of leaks and a proven process to address them will help deliver energy savings. If addressing leaks is part of routine maintenance without a need to deliver visible energy savings, the statistical data will assist in setting simple goals with the greatest potential return.
When leak mitigating actions must deliver hard savings, following the SMART steps will help ensure desired results can be achieved and validated.
Mark Krisa is Director, Global Services Solutions for Ingersoll Rand
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