Molding a reliable power system: DTE Energy Technologies provides cogeneration system for California plastics company - Power Generation - Medway Plastics Corp

Diesel Progress North American Edition, May, 2003 by Mike Brezonick

Medway Plastics Corp. (MPG), Long Beach, Calif., is an advanced custom injection molding plastics company that offers a diverse range of products manufactured from commodity and engineering-grade thermoplastic resins. Its products include beverage containers, produce baskets, bread trays, audio speaker enclosures and office furniture. The company operates out of five separate buildings, which include an administrative! warehouse site, three production buildings and one R&D location, all of which are served by the local gas and electric utilities.

During the California energy crunch of two years ago, MPG rented portable generators, shed load, and worked odd shifts and weekends in order to balance productivity requirements against rising power costs, outages and random blackouts. With funds available through the local electric utility's self-incentive program, MPG determined that an on-site power system was in its best long-term interest. As the company operates 24 hours a day, seven days a week, such a system would ensure that work could continue with no disruption even during peak power periods.

When MPG began researching its on-site power options, it requested that DTE Energy Technologies (DTE Tech), Farmington Hills, Mich., submit a bid to provide a turnkey installation for a 1000 kW generator package. A subsidiary of DTE Energy Co., DTE Tech was established in 1998 and specializes in distributed generation products and services to solve the energy-related needs of residential, commercial and industrial customers.

The heart of DTE Tech's program is the energy/now line of power generation and cogeneration products. Covering an output range of 5 kW to 2 MW the energy/now portfolio includes advanced internal combustion systems, Stirling engine systems, mini-turbines and fuel cell-powered energy modules that provide electric and thermal power.

Along with the 1000 kW option, DTE Tech was also requested to submit a proposal for three 375 kW energy systems with a cogeneration option that would allow MPG to utilize the heat from the engine jacket water to drive a 151-ton, single-effect, vapor absorption chiller which is used for cooling operations related to the injection molding process. The multiple-unit approach was considered because that alternative would allow the company to manage its plant load even if one unit should be off-line. MPC ultimately decided on the three smaller units. DTE Tech involved its application engineering and project management group to finalize design and complete construction.

Gerald Hutchinson of MPG said there were several factors the company weighed in selecting the energy/now cogeneration systems, including the fact that a reliable supply of quality power has sometimes been an issue in California. "We knew that the energy now products would help increase our reliability and will save us on our energy bills in the long run," Hutchinson said. "Plus, we could be more environmentally friendly about the way we use electricity."

The units that MPC selected were DTE Tech's containerized ENI 415S cogeneration systems. Each module has a gross output of 375 kW, with cogeneration provided through recovery of the engine jacket water heat.

The unit is based on a Waukesha Engine gen-set operating at 1800 rpm. DTE Tech became one of Waukesha Engine's Power Energy Partners list fall, and offers cogeneration systems from 280 to 830 kW as part of the energy/now program.

The ENI 415 package consists of a 24 L, in-line, eight-cylinder Waukesha VGF 24G natural gas engine that drives a Leroy-Somer synchronous generator.

A dual core horizontal radiator from Young Touchstone provides cooling for engine jacket water and oil and intercooler circuits. The radiator assembly is positioned in the front of the enclosure and a single fan draws ambient air through louvers in the walls. The fan, supplied by Young Touchstone, is controlled by a variable frequency drive (VFD) which raises or lowers fan speed to provide control of both engine jacket water and inter-cooler water return temperatures.

Young Touchstone also supplied the plate-and-frame heat exchanger that delivers 1.2 million BTU/hr of jacket water energy to the Thermax chiller hot water loop. An integral three-way bypass valve provides control of water flow to the plate-and-frame unit.

Because the units will operate in the South Coast Air Quality Management District (SCAQMD), they are fitted with catalytic silencers from Silex. The silencer unit, which is housed within the gen-set enclosure, incorporates a three-way catalyst supplied by Johnson Matthey.

The electrical controls for the generator were supplied by ASCO. The integral generator breaker is rated at 800 amps at 480 Va.c. and the panel also includes a Woodward EGCP-2 engine controller, a GE Fanuc 90-30 PLC, a QuickPanel Jr. HMI display and a Basler synchronizing relay.

Each gen-set module includes a 24 Vd.c. battery pack rated at 1000 CCA and DTE Tech supplies an on-board charger which automatically recharges the batteries when the voltage drops below the normal level. Each also includes a 55 gal. engine lube oil reser-voir, which maintains oil level in the engine's 28 gal. crankcase on an as-required basis.