Industrial Utility Efficiency    

Plastics

The plant produces both molded and blow molded plastic parts on a 5 day per week, three shift schedule. Production and maintenance sometimes occurs on weekends, occasionally requiring the air compressors to run on a 24 x 7 basis so the practice was to leave the compressed air system always pressurized. The system consisted of three modulating lubricated screw compressors one sized at 150 hp and the others 125 hp (3 units), each controlled with their local compressor controllers.
The PET industry is in a state of flux right now. A number of new bottle blowing facilities are being brought on-line. They are in the “discovery” phase right now as they realize how challenging the required compressed air systems are to manage – from an energy efficiency standpoint. The average high-volume stretch blow molder (SBM) working with PET usually has 2,000 to 4,000 horsepower of installed air compressors with the related energy costs running between $1 to $4 million per year. This typically represents 35-40% of the facilities’ total energy bill.
Bottling companies and breweries, in California, are benefiting from a three-step system assessment process aimed at reducing the electrical consumption of their compressed air systems. The three-step process reduces compressed air demand in bottling lines by focusing on open blowing and idle equipment, and then improves the specic power (reducing the energy consumption) of the air compressors.
CVP System, Inc.’s MasterPACKer Eco+™ Breaks Down Barriers to Cost and Energy Savings Through Improved Modified Atmosphere Packaging Technology Worldwide, Tesco, a global grocery and general merchandise retailer headquartered in Cheshunt, U.K., initiated the demand for modified atmosphere packaging technology in the early 70s. It became one of the first grocers to move away from employing an onsite butcher to using a central processing/distribution system.
As in most industrial categories, compressed air is critical to the operations of a plastics plant whether it is blow molding, injection molding, or other processes. The opportunities to improve supply side (compressor room) efficiency are similar to all industrial compressed air systems, but are even more prevalent in some plastics facilities, especially blow molding.
Most P.E.T. bottle-blowing machines require anywhere from 550 psig (38 barg) to 580 psig (40 barg) and an air flow of 247 cfm FAD (420 m3/hr) to 3700 cfm FAD (6290 m3/hr). The air compressor technology used most prevalently for this application is the double-acting, oil-free, water-cooled, reciprocating air compressor. With the higher pressures and air flows that are required, the P.E.T. bottle blowing market is a strong niche market for the double-acting oil-free reciprocating (piston) compressors.  
The NPE2009 international plastics showcase was held June 22-26 in Chicago’s McCormick Place. While attendance was down from NPE2006, the preliminary total of visitor registrations numbered 44,000. Sustainability and energy efficiency was a prominent topic in the booths of exhibitors. Manufacturers of compressed air and injection molding equipment had many developments with Sustainability to show the visitors to NPE2009.
Resin drying is a critical step in the manufacturing process of injection molding, extrusion molding and stretch blow molding.  Compressed air resin dryers are one of the most commonly used dryers in the plastics molding industry. Recent advancements in compressed air membrane-type resin dryers, have reduced the associated energy costs significantly.
Over the last several decades, Air Power USA has reviewed many various types of plastic injection molding operations throughout the U.S.
Compressed Air Best Practices interviewed Paul Lukitsch.  Mr. Lukitsch is the Regional Facilities & Energy Manager for Millipore Corporation.
The facility is a plastics injection blowmolder and is a division of a large corporation. The following information was produced from a compressed air system assessment done over seven days.