Energy Wise: Uncovering secrets through energy data analysis
By Anatoli Naoumov
June 6, 2019 - Energy is the lifeblood of manufacturing, since every process requires it—and just as blood tests enable doctors to diagnose diseases, so too will regular monitoring and adequate analysis of energy use allow you to identify and diagnose deficiencies in your facility’s manufacturing processes.
By Anatoli Naoumov
The following are two examples of such analysis with regard to natural gas consumption.
Industrial baking ovens consume a lot of natural gas, but their daily consumption varies, depending on production volume, the weather and even the operator’s style.
To determine whether one such oven was overburning gas or maintaining efficiency as per its specifications, we performed a regression analysis of its energy consumption, covering a period of four years since the oven was commissioned.
As might be expected, efficiency generally decreased over time. What was surprising, however, was how—for three years in row—the oven’s efficiency sharply dropped in April and then stayed stable throughout the rest of the year.
This puzzle was solved after we discovered the oven’s annual maintenance routine, performed every March, included calibration of thermal sensors inside it. This had been duly performed, but it turned out the contractor’s own tools were out of calibration.
So, for three years in a row, the contractor was manually reducing the oven’s efficiency. Over that period, the baking process deviated further and further from an optimal state. Dryer and lighter loaves were being shipped to stores.
When the contractor returned and recalibrated the sensors with proper tools, oven performance came back to specs—and so did bread quality.
Savings melt in winter
Accurate analysis of energy use does not always bring a happy result.
Timing of measurement proved problematic for an automotive manufacturing plant that produces die-cast parts. Repairs to its aluminum melter, performed one March, promised a reduction of natural gas consumption. To report the savings, the facility’s maintenance manager compared natural gas consumption per tonne of metal for a five-month period before and after the retrofit work.
The savings over that period exceeded the best estimates by far—but by the following January, those savings had mostly disappeared. Had the repairs failed? No, the data analysis procedure was wrong.
The melter needs more natural gas to melt a tonne of aluminum in the winter than in the summer, as the metal needs to be warmed by a further 30 to 50 C. The repairs were fine, but the ongoing savings had been overestimated.
What’s in it for you
Analysis of continuously collected energy consumption data is the most cost-effective way to ensure manufacturing equipment operates within its specs, the settings are correct and no bypasses or temporary settings have been forgotten. It’s like having a diligent maintenance manager watch every machine every hour of every day, but more reliable and much less expensive.
Anatoli Naoumov is a managing director and ‘chief energy waste-buster’ at GreenQ Partners, which helps identify, implement and report energy-saving projects. He has been named a Certified Measurement and Verification Professional (CMVP) by the Association of Energy Engineers (AEE) and the Efficiency Valuation Organization (EVO). For more information, contact him at email@example.com.
This column originally appeared in the May 2019 issue of Energy Manager Canada magazine.