As frequency converter manufacturers continue to work in an increasingly globally competitive environment, it is important for industrial facilities managers to evaluate the cost of supplying utilities to their operations. A large part of a facility`s operational costs can be attributed to the heating, ventilation, and air-conditioning (HVAC) equipment and to the air filtration systems connected to them to help keep the indoor air clean and safe. Precise Manufacturing installed four 3-HP, 4,500-CFM packaged air cleaners to filter the air in a 120- by 35- by 22-ft. welding fabrication area. Precise frequency converter manufacturing installed four 3-HP, 4,500-CFM packaged air cleaners to filter the air in a 120- by 35- by 22-ft. welding fabrication area. Packaged air filtration systems can handle many of the everyday nuisance dusts, vapors, fumes, and smoke in industrial facilities (see Figure 1). Careful selection and integration of this safe, ductless equipment can help companies comply with the current OSHA regulations and provide years of energy-efficient air filtration. Packaged air cleaners can provide a favorable cost of ownership for all types of inverter manufacturing, warehousing, and assembly workspaces. New developments in filtration equipment, replacement filter technology, and proper application of electrical systems and controls can help save thousands of dollars in utility costs annually. Each facility has its own unique set of specific needs. Managers must carefully evaluate which engineering controls can help them meet their long-term goals for creating a clean, safe, and efficient workspace. Media-style packaged air cleaners can be a cost-effective means of controlling dust, smoke, mist, and fumes in large work areas. The types and amounts of materials being collected will determine the design and application of the air filtration system. Selecting the proper stages of filtration media, paying attention to motor and blower efficiencies, and using the latest frequency converter controls can greatly reduce operational energy consumption costs. How to Select the Best Process Step 1. First, determine the air exchange rate (AER) that best fits your application needs (see Figure 2). Step 2. Next, determine the total cubic feet of your plant work area. Total cubic feet = L x W x H (maximum height 20 ft.) Where: L = Workspace length W = Workspace width H = Workspace ceiling height. Note: The maximum ceiling height used in the AER calculation is 20 ft. because smoke, dust, and fumes stratify below this height. For example, a 24-ft. ceiling height = 20 ft. Step 3. Next, divide the total cubic feet by the AER determined in Step 1. Step 4. Choose the cubic feet per minute (CFM) of the units you prefer to install. For example, to select the proper air filtration system for a welding operation (5 AER) in a 150- by 60- by 18-ft. workspace (162,000 cubic feet) with 4,500 CFM would require seven 3-HP (for a total of 21 HP) units (see Figure 3). This setup will provide a total of 31,500 CFM with approximately a 5-minute air exchange rate in this workspace. Electrical Controls Proper selection of electrical controls can help make a packaged air system even more energy-efficient. In this example, you could use seven 3-HP frequency converters. Preprogrammed frequency converters in Type 1 enclosures will soft-start the motors, slowly ramp up as the filters load with particulate, and then offer operational feedback on each unit. One central start/stop panel can be used to control the units, with green running lights and red filter service lights for visual cues. The units would then run on 7 HP total at start-up (new filter media) and slowly move up to the maximum 21-HP draw. The soft start reduces the magnitude of electrical spikes, extends motor life, and controls the airflow rate through the filter media. The consistently slower, controlled speed of air through the specified filter media will stop the filters from prematurely binding (plugging) and will increase the interval length between filter replacements. Energy-efficient Air Filtration Case Example Precise frequency converter manufacturing, located in southeast Nebraska, built a new 41,250-square-foot fabrication facility in 2006 (see lead image). The facility is air-conditioned, and the owner wanted to try to keep the air environment clean from start-up. Two cartridge dust collection units, installed outdoors, source-capture the smoke and fumes generated directly at each laser cutting table. Two ¾-HP, 3,000-CFM packaged air cleaners filter the nuisance dusts that escape from above the laser tables. Four 3-HP, 4,500-CFM units filter the air in a 120- by 35- by 22-ft. welding fabrication area. In addition, two small 1-HP exhaust fans are used during mild-temperature seasons. The total horsepower of the air filtration system used to control the welding smoke and fumes in a six-station welding bay plus two collection units above the laser tables effectively is 1.5 + 2 + 12 = 15.5 HP (not including the outdoor dust collection for the laser tables), more...
