Meat packing plant solves temperature mystery by monitoring energy

You can't fix what you don't measure: Rising energy costs warrant monitoring system.

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Meat packing plants all over the country were closing, and many others suffering financially. The Mariah Meat plant in Columbus, Indiana, was no different. Utilities represented the plant’s third largest expense, after raw product and personnel, and yet the company had little real knowledge where those dollars were going. In fact, expenditures had become so great that Mariah had sought a no-cost energy audit from the local electric utility.

When plant management, including President John Stadler, read the utility’s audit report and saw that its only suggestion for savings was a switch to more energy-efficient bulbs for the lighting system, they realized the auditors had no clue about the complex systems in the Mariah facility. With electricity accounting for two-thirds of the plant’s annual utility costs, it had become clear that the company needed to reduce its power bill if it wanted to remain in business.

To better understand and gain control of its energy bills, Mariah turned to Holmes Energy, an energy consultant specializing in facility energy conservation, system operation, control and maintenance.

Holmes Energy determined that the first phase of the Mariah Meat Packing energy management project should be discovery. This included gathering equipment lists, system schematics and copies of past utility records to provide a breakdown of electric, gas, water and sewer costs. Further examination and discussion revealed, when it came to electricity, the refrigeration compressors, cooling towers, air compressors, pumps, lights and production equipment were all running for long periods, and all were thought to be using a good deal of power. The question was one of distributing that power.

Monitoring and data collection

Holmes Energy designed and installed an AutoPilot Energy Information System to monitor, identify, manage and eventually reduce Mariah’s electrical costs. The AutoPilot system, based on hardware from Opto 22, used multiple panels installed at key locations across the plant and included I/O connections to machinery and equipment, as well as the facility’s electric meters.

The connections to Mariah’s individual machines and equipment provided the granularity needed to detect even small changes in power draw and the ability to identify precisely the heaviest energy consumers.

The refrigeration compressors, cooling towers, air compressors, pumps, lights, and production equipment were all running for long periods, and all were thought to be using a good deal of power.
The refrigeration compressors, cooling towers, air compressors, pumps, lights and production equipment were all running for long periods, and all were thought to be using a good deal of power.

“Monitoring the meters alone would certainly show when every dollar was spent; but the rest of those I/O points would prove even more beneficial in that they would track exactly where those dollars went within the plant,” explains Bill Holmes of Holmes Energy. Because most of the major equipment at Mariah already had its own, independent control systems that functioned well and that plant operators were familiar and comfortable with, the AutoPilot system was designed strictly for monitoring and data acquisition purposes — with no control functions. The AutoPilot system hardware also used standard communications technologies, allowing Holmes to access and review the energy data remotely via a PC each day and provide ongoing analysis and recommendations. The real-time and historical user interface screens the system provided were representations of the actual plant and equipment.

Reports on equipment performance and consumption were made available not only in units of energy, but also in dollars. Data presentation in this format allowed Stadler and others to understand how much each plant system was costing every hour of every day. The aggregated data would soon show that Mariah’s refrigeration system accounted for two-thirds of the plant’s total electrical consumption and costs. It thus became obvious that the initial energy management efforts should focus on this system. Shortly after the energy monitoring system was installed, an industrial power engineer with the local electric company phoned Holmes and informed him Mariah was looking to add $100,000 in new electrical transformers, in preparation for adding more refrigeration equipment before summer. Holmes knew the data showed that the plant already had at least twice the refrigeration capacity it needed. A meeting was set, and the plant manager and engineering staff that had requested the new equipment were presented with evidence that showed the facility should not be having so much trouble keeping the meat cool on hot days.

“They were looking at what they were using, and I was looking at what they needed,” says Holmes. “The data from our monitoring system, when compared to the model of the energy needs of the plant, showed that even on the hottest day of the year, the plant had between two and three times the refrigeration capacity it would need. Rather than spending a lot of money on new transformers and chillers they didn’t need, we needed to find out why what they already had wasn’t doing its job.”

Dig deeper

The newly acquired data provided an opportunity to reexamine the plant’s thermodynamics and possible reasons why cooling needs weren’t being met. For instance, when live, 250-lb hogs were delivered to the plant for processing, each animal’s body temperature was about 103° F. Regulatory guidelines require that after processing, food product temperature be lowered to the cooler or freezer temperature within a fixed number of hours. Using engineering physics and the specific heat of hog flesh, one can calculate exactly how much heat needs to be removed each hour and each day from each hog and from the total plant, and thus how much refrigeration is required. Mariah’s refrigeration system needed to remove the heat from the warm product brought into the coolers and freezers. It also had to remove heat from people, lights, motors and the scalding water used for cleaning. In the summer, the refrigeration system also battled the heat that came through the roof and walls and the air that leaked in from the outside. Because parts of the building were 75 years old and the insulation wasn’t very good, it was natural for the employees to assume these were major reasons it was hard to keep the plant cool. Whatever the reason, when all was said and done, in terms of energy balance for the total plant, “heat in” had to equal “heat out.”

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