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Electric Facilities:Power Plant
Manitowoc Public Utilities’ power plant has grown significantly since the late 1800's when John Schuette started the Electric Light Company. In 1915, a year after the City purchased the electric utility, the plant was moved from Quay Street to its present location. Today, the plant houses a range of 75 years of power generation technology. Much of the plant equipment has been modernized using the latest digital technology available to help improve plant efficiency, safety, and pollution control. While some of the equipment in MPU’s power plant might seem relatively old, its dependability is exceptionally high, thanks to a dedicated staff and ongoing maintenance and modernization programs. Originally designed to burn high grade stoker coal, MPU has invested in pollution control and fuel handling capabilities to burn lower cost western fuels. Boiler number 5 operates at 450 pounds per square inch of steam pressure at 700 degrees Fahrenheit, while units 6 and 7 operate at 900 pounds per square inch of steam pressure at 900 degrees Fahrenheit. Boiler number 8, which was installed in 1989, uses state of the art circulating fluidized bed combustion technology, and also operates at 900 pounds per square inch of steam pressure at 900 degrees Fahrenheit. This boiler is the cleanest and most efficient unit that MPU employs. These turbines spin 24 hours per day, 365 days per year. They are only taken out of service once per year for inspection and maintenance. Every five years a major overhaul is done. RECIPROCATING DIESEL GENERATORS Because of the quick start-up and dependability of these units, MPU can purchase inexpensive “interruptible” power on the wholesale market, and back it up with the diesels. The power plant operator has many different tasks. From their view of instrumentation panels and computer screens, they monitor and control all parts of the power plant. They also have monitoring and control capability of all of MPU’s substations located around the community. Another important part of their job is scheduling power resources to meet the community's demand for power. This task involves several steps: First, an hourly energy forecast of the system load is made, taking into account the weather forecast, the day of the week, holidays, and major industry plant shut downs. Second, the operator checks what generation resources are available in the plant to match the load, and at what cost. Third, the operator checks the wholesale market to see what power is available for purchase from other utilities. Transmission availability is also checked, and a delivered cost is calculated. Finally, the operator schedules all of the energy resources, using the best economic mix. The operator also takes emergency telephone calls from customers if there is a power outage or other electrical emergency. Custer Street Energy Center
The
General Electric Frame 5 turbine /generator at the
Custer Street Energy Center was purchased used from a
Union Carbide Plant in New Orleans, Louisiana in late
1998. The unit was rebuilt and placed into service on
June 1, 1999. Built at a cost of $8.2 million, the
Custer Street Energy Center also features a 22-megawatt
distribution substation, serving rapidly growing
industrial loads in the City's I-43 Industrial Park and
other west side developments. The
Custer Street Energy Center’s Combustion
Turbine/generator is used for supplying peaking power to
the City of Manitowoc, and can be used for emergency
power in the event of a blackout. The
turbine is similar to a jet engine, and can be run on
either diesel fuel and natural gas. The turbine is
started with a 500 horsepower, 12 cylinder Detroit
diesel engine. Basic
equipment for the turbine/generator includes a
compressor, combustor, turbine, and generator. The
rotating compressor sucks in atmospheric air,
pressurizes it, and forces it into the combustor, or
furnace, in a steady flow. Fuel forced into the
compressed air burns, raising the temperature of the
mixture of air and combustion gasses. This high energy
mixture then flows through the turbine, dropping in
pressure and temperature as it does work on the moving
turbine blades. Combustion gasses leave the turbine at
atmospheric pressure and high temperature. The
turbine is connected on a common shaft with the
compressor and rotates at 5,100 revolutions per minute.
The generator is connected to the turbine shaft through
a reduction gear, which revolves at 3,600 revolutions
per minute. The
compressor has 17 stages of fan blades, sucking in a
tremendous amount of air through a series of inlet
filters. The combustor has 10 burners oriented in a
radial configuration. The turbine has two stages, and
consumes 180 gallons of fuel per hour at full load. MPU’s
combustion turbine/generator is also equipped with water
injection into the combustion chamber to control
nitrous-oxide emissions, and silencers on both the
intake and exhaust stacks to control noise. The Custer Street Energy Center combustion turbine/generator can be started and deliver electric power in about seven minutes. Full output of 24.5 megawatts can be achieved in fifteen minutes. The 13,800 volt generator output is connected to the electric system through underground cables to the adjacent distribution substation. The unit has the capability to be “black started”, meaning that no auxiliary power is needed to start the unit.
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FUEL
STEAM TURBINE GENERATORS
For peaking, backup and emergency power, MPU installed two 5 megawatt diesel generators in 1985. These units are powered by twelve cylinder, 7,320 horsepower internal combustion engines, and can be fueled with either diesel fuel or natural gas. The engines are kept warm at all times, and can be up and running in as little as 5 minutes.