This article originally appeared in the October 2014 print edition of Food Manufacturing.
The Food Manufacturing Brainstorm features industry experts sharing their perspectives on issues critical to the overall food industry marketplace.
In the first installment of this three-part series, we ask: What are some areas of investment that food manufacturers should utilize to improve their energy management?
Industrial refrigeration accounts for the largest energy usage in a manufacturing facility, often up to 60 percent of a plant’s total operating expenses. As a result, this is the first area where many manufacturers choose to invest to improve energy efficiency. An integrated approach to optimizing the mechanical system is one of the most effective ways to reduce energy costs. Too often, engineers look to optimize each individual component of their system rather than looking at the system as a single, integral unit. Every time a new piece of equipment is added to the system, if it’s not properly optimized within the scope of the entire system, you’ll end up with wasted energy and operational inefficiencies.
Screw compressors are designed to operate at 100 percent or they lose efficiency as the load decreases. Installing VFDs can decrease this effect and increase overall efficiency. Adding VFDs to condensers and evaporators will allow the fans to change speed, which saves power because fans operate on the cube law. It also can avoid unnecessary stops and starts, which require additional energy and leads to mechanical wear.
Saving condenser horsepower is often offset by higher compressor horsepower and vice versa. It is important to balance the two and run at the optimum system efficiency point, which will change depending on loads and weather. Modern refrigeration control systems allow you to better manage your entire system and continually optimize energy use. If you’ve experienced issues with your existing system including unstable pressures, idling or lightly loaded equipment, or the inability to trim fans, it’s probably time to evaluate the overall system and upgrade the control system.
In addition to mechanical efficiencies, automation can greatly improve refrigeration efficiency and optimize energy use. Automation allows users to generate trend analyses, alarm logs, energy management data and runtime reports in real-time. This data allows you to make the necessary changes and modifications to ensure the refrigeration system is running at optimal efficiency.