- How We Generate Power
- Electricity from Gas
Electricity from Gas
To prevent icing on the compressor blades, outside air passes through the pre-heaters to be warmed when the ambient air temperature is below 43 degrees Fahrenheit. Air at 258,000 cubic feet per minute (cfm) continually passes through the pre-heater and enters the filter banks where it is cleaned. Ambient air must be filtered to keep the engine as clean as possible as a clean engine is an efficient engine.
The filter bank is composed of 120 filters, each filter resembling those used on large diesel engines or semi-tractor trailers.
Filtered air enters the engine through the air intake, passing stationary blades to direct it at "the most efficient angle of attack" for initial compression.
View images of the Air Intake System that show the process that air goes through to generating energy.
Liquids are removed from the natural gas using a mechanical moisture separator and then methanol injection is used to remove whatever remains. At full load, the gas turbine requires 250,000 cubic feet per minute (cfm) of fuel supplied at 675 Pounds per Square Inch (psi). This high pressure fuel is delivered to the engine through a 4 inch fuel line. The fuel line meets the fuel header where the gas is distributed to 30 fuel nozzles.
View images of the Fuel Process and liquids removing themselves from natural gas.
Water is injected before the high pressure compressor to cool the turbine, allowing increased horse power. Water is also injected into the combustion chamber to control Nitrogen Oxide (NOx) emissions.
Water entering the engine must be extremely clean and free of dissolved minerals. For example, calcium, which is normally present in tap water, must be removed. All water used in the engine goes through reverse osmosis (that is, the water passes through a membrane which allows the water to flow through; most minerals cannot pass through the membrane).
The water next undergoes demineralization. The water passes through resins where the positively and negatively charged minerals are attracted and attach to the resin beads. This demineralized water is held in storage until needed. When called upon to be used, the water again goes through the demineralization process to be sure it hasn’t picked up any contaminants from the pipes and tanks.
View images of the Water Process to generate gas electricity.
The gas turbine engine is connected to the generator, which is a coil of copper wire with an electromagnet in the center. The combustion turbine engine spins the magnet at 3600 revolutions per minute (rpm) exciting the electrons in the coils producing 60 cycles per second (hertz) power at 13,800 volts.
Power generated from the combustion turbine generator is transmitted to a step up transformer which increases the voltage to 34,500 volts for transmission to Board of Public Utilities (BPU) distribution switchgear.
These high voltages require specialized cable to prevent the electricity from shorting to ground.
View images of the Power Generation System.
Thousands of cubic feet of exhaust exit the gas turbine at 800 degrees Fahrenheit every second of operation. It would be a shame not to take advantage of this energy. By channeling the hot exhaust through a Deltak heat recovery steam generator, another thirty percent of the energy is reclaimed from the natural gas being burned.
An eight-foot valve channels the exhaust out the bypass stack until the turbine reaches peak output. The door is then retracted and the hot exhaust flows through a series of four heat exchangers that are roughly the size of a two-story home. This is where the system shows it versatility. The heat exchangers can preheat the boilers, provide district heat boiling water to steam and then superheat that steam to run an additional generator next door. The gases exit up the rear stack at 300 degrees Fahrenheit with sixty-three percent of the heat reclaimed.
View images of the Combined Cycle System that is used to generate electricity.