Machinery
Here, we'll take a look at two categories of machinery, common in many businesses, that use a significant amount of energy refrigeration and motors.
Refrigeration
Refrigeration and process cooling systems typically consume more electricity than other industrial processes. Energy efficiency measures do more than just reduce utility bills. They can prolong the useful life of expensive capital assets such as condensers and compressors, or even improve product quality, production efficiency and worker comfort.
1) UPGRADE
Whenever aging equipment needs to be replaced, consider purchasing the most efficient models possible. That goes for the insulation materials and control systems as well.
Variable Speed Drives (VSDs) can be added to evaporator fans or condenser fans to significantly improve partial load control and reducing energy use. A VSD-equipped evaporator fan, for example, can reduce fan energy use by as much as 86 percent, depending on operations. VSDs can make refrigerated spaces more comfortable for workers and less noisy.
2) MAINTAIN or TUNE-UP
Routine maintenance can have a big impact on the energy use of refrigeration equipment. Check for plugged line filters and ensure that fans, motors and belts have proper air circulation. Condenser coils should be cleaned and checked for missing or plugged nozzles. Defrosting evaporator coils. Check seals and seams for leaks.
3) CONTROLS
A computer-control system allows specific pieces of equipment to be automatically managed or programmed, eliminating the need for manual adjustments. Evaporator fan controls can be easy to install and inexpensive. They can ensure fans are cycled on and off during periods of low activity or when outdoor temperatures reduce cooling loads. Some fans come equipped with two speeds, for full capacity and half-capacity.
4) BEHAVIOR
For starters, you can reduce thermal leaks by keeping doors closed consistently, and by making sure employees reduce wasteful practices. Perhaps less obvious, strive to limit partial loads for compressors, evaporators and condensers. As load percentage decreases, so to does efficiency. And investigate demand-shifting strategies. New studies on passive thermal energy storage indicate that, in some cases, it may be possible to shift refrigeration operations to off-peak hours. The efficiency of your system can increase because off-peak hours tend to be at night when outside temperatures are lowest.
Motors
Motor systems consume as much as 60 percent of all electricity in the United States, half of which is used in industry. A well-designed and well-maintained motor system can reach 90 percent efficiency - meaning that 90 percent of the input energy gets converted to useful work. Unfortunately, only a small portion of the motors out there achieve this. The good news, though, is that as older motors are retired, opportunities arise for newer, more efficient technologies.
1) UPGRADE
Remember, the purchase price of new motors can account for just 2% of the total lifetime cost, while electricity can account for nearly 98%. Investing in premium efficiency motors generally pays back any incremental costs in short time period. They typically improve energy efficiency between 2% to 10% percent compared to standard motors. Keep this in mind when deciding whether to replace an old motor or repair it.
Variable speed drives can substantially improve energy efficiency, particularly for a motor that often runs at partial loads. VSDs can save as much as 50 percent of a system's energy use while prolonging equipment life and giving operators greater flexibility.
2) MAINTAIN
Just like your car needs regular oil changes and tune-ups, motor systems must be routinely maintained. Not only does proper maintenance protect expensive equipment and reduce energy use, it typically gives plant managers advanced warning when equipment starts to wear and may need to be replaced, thus minimizing or avoiding costly downtime. Keep motors clean to avoid premature wear. And lubricate all moving parts on process equipment and motor bearings to minimize friction, improve efficiency and extend the useful life of equipment.
3) CONTROLS
Automated control systems can ensure process equipment runs at its most energy efficient, depending on work flow, time of day, load, etc.
4) BEHAVIOR
The way you use motors can significantly impact energy use. Be sure to match size to load. Motor systems are often sized to accommodate expected peak load, with little or no allowance for partial loads. Consider strategies such as staging of equipment, automatic shutdown, parallel systems and downsizing. Consider adjusting the impeller in pumps to increase efficiency. And protect motors from high ambient temperatures or operating temperatures whenever possible. Overloading the motor, improper supply voltage, frequent start/stops, blocked cooling systems and variable frequency drives can lead to temperature rise.