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CPS Energy ships low-sulfur coal by train from Wyoming to the J.K. Spruce Plant. More than 1,300 individual railcars each carry a maximum of 120 tons of coal. Once the train arrives at the plant, the coal is unloaded and stored.
Coal enters the plant by conveyer belts that drop the pea-sized coal into five silos. At the bottom of each silo, a pulverizer grinds up the coal into a talcum powder consistency. The coal is grinded to make it easier to deliver and burn as a fuel.
Large fans blow the coal powder into a boiler that stands 20 stories high. The coal fuels a massive fireball that can reach 3,000 degrees Fahrenheit. Steam pipes in the boiler carry ultra pure water that has been pumped from the lake and treated. The heat of the furnace converts the water into steam. With a temperature of 1,005 degrees and a pressure of 2,400 pounds per square inch (PSI), the steam is sent over a steam turbine through a series of pipes. Low pressure, intermediate pressure and high pressure steam are used to spin the blades of three turbines at a rate of 3,600 revolutions per minute (RPM).
The turbines, connected to a generator by a shaft, power the generator. The generator is made of a large magnet spinning inside copper windings. Electrons flow from the copper along a conductor to create 24,000 volts of electricity. In order to push the electricity from the plant further out into the city, a step-up transformer is needed to increase the power from 24,000 volts to 345,000 volts to carry electricity over transmission lines to customers.
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