Energy Management Maintenance

You Can’t Manage What You Don’t Measure

EP Editorial Staff | January 12, 2016

Fluids, compressed air, boilers, heat exchangers, and steam systems can waste significant energy in your plant if their performance isn’t constantly monitored and measured.
Fluids, compressed air, boilers, heat exchangers, and steam systems can waste significant energy in your plant if their performance isn’t constantly monitored and measured.

Fluids, compressed air, boilers, heat exchangers, and steam systems can waste significant energy in your plant if their performance isn’t constantly monitored and measured.

Just how much revenue can your process operations afford to lose?

Shakopee, MN-based Emerson Process Management (emersonprocess.com) has released an Engineer Insight Report to help industrial end-users better understand where and how energy can be saved in their operations. Entitled Top 5 Measurements for Energy Efficiency, it identifies priorities with equipment systems that “should be a concern for any plant-management team looking to gain better insight into process energy use.” The report also details some real-world successes and energy savings realized by other end-users and highlights the measurement technologies they leveraged.

Utility Fluids (metering flow and managing use)

Utility fluids, i.e., water, air, gas, and steam, are the lifeblood of a plant. A shortage of any one of them could lead to a shutdown. Emerson acknowledges that, while every plant is different, for most, it’s reasonable to say, that 5% to 15% of a site’s energy is wasted in the form of lost or misused utility fluids. Metering the flow and managing the use of utility fluids could be an opportunity to save between $1 million and $15 million annually.

Compressed Air (measuring flow to identify leaks and manage use)

Compressed-air systems in plants are major energy users and generally have many leaks and other issues leading to waste. Measuring flow in a compressed-air system helps identify areas of excessive use and ways to better manage overall air use. Measuring air use is best done with several points of flow measurement throughout the system, i.e., at each compressor, at headers, and at major branch lines. More measurement points allow tighter leak control and better management of system health.

Boilers (improving drum-level measurement)

In boilers, the water level in the steam drum must be precisely controlled to optimize steam production, maximize boiler efficiency, and maintain safety. If water levels are too low, there’s a risk of damage to the boiler—and a significant risk of costly boiler trips. If levels are too high, water could be carried with the steam, reducing heat-transfer effectiveness and possibly damaging  downstream turbines. Steam-system performance is most efficient when boiler operation is stable and costly shutdown, purge, and re-start cycles are avoided. According to Emerson experts, reliable drum-level measurements are important in achieving that desired condition.

Heat Exchangers (predicting and detecting fouling)

Process facilities may have hundreds of heat exchangers that can foul over time, directly affecting production capacity, maintenance costs, and energy use. Heat-exchanger fouling is accelerated by many factors, including sediment, corrosion, decomposition, and crystallization. Unfortunately, due to the difficulty and perceived high cost of real-time monitoring, many of these units may only be checked periodically, during field rounds. Operators using visual and manual measurement methods are often challenged to spot signs of contamination and, over time, build-up occurs—impeding heat transfer, reducing throughput, and driving up energy consumption. Energy costs rise when fouling requires additional heat for a needed temperature change.

Steam Systems (monitoring steam traps)

Most industrial plants use steam heat to provide the energy that drives processes. Boilers and steam-distribution lines are the obvious components of these systems. However, critical steam traps, i.e., mechanical valves that let condensed water out of the system while keeping the steam in, are frequently overlooked. A large plant can have thousands. They fail in one of two ways: open or closed. An open trap leaks steam, wasting energy. A closed trap lets condensed water build up in the steam pipe, creating reliability issues and causing “water-hammer” events that can damage the steam system and connected equipment. Steam traps have an average life expectancy of about five years. Regular replacement of failed traps is essential for proper steam-system operation.

Download the complete report, along with a free White Paper entitled Process Energy Efficiency: Measure, Monitor—Then Improve, at emr.sn/Mwn. MT

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