Prime Energy Systems

About Turbine-Generator Sets and Cogeneration

Known worldwide for reliable, high-quality steam turbines, Prime Air offers a range of turbine-generator sets to suit your needs.  Using a process called cogeneration, These devices allow your company to generate its own power using the steam or waste fuel that it already produces, drastically reducing power costs.  Cogeneration is becoming an increasingly popular way to save money and increase plant efficiency. 

How do turbine-generator sets work?   

A turbine works by using a steam pressure drop to spin a shaft inside the housing.  In a turbine-generator set, this shaft will be connected to an electric generator.  Electricity will be produced based upon how much steam flows through the turbine, and how much the steam's pressure is allowed to drop while inside.  If your plant produces steam at a high pressure and then reduces it for use in any process, you can use the turbine to reduce the steam pressure and simultaneously generate electricity.  A steam turbine will take the place of a pressure reducing valve and allow you to make more power with the energy that was once wasted.

How will the turbine-generator affect your current electrical system?

Commonly, turbine-generator sets are used to provide a portion of a plant's electrical needs.  This means that you will still be connected to your current utility, and still be purchasing some of your power from them.  If your generator were to be shut down for any reason, you would still have access to your utility's power, just as you do now.

For more information about generators, see the section at the bottom of the page.

How much will cogeneration increase our plant's efficiency?

    The steam your plant's boiler creates contains energy in the form of heat and pressure.  When the steam is passed through the pressure-reducing valve, the pressure is lost and energy is wasted.  Passing the steam through a steam turbine will allow you to keep any heat and pressure you need for your process, but the excess pressure will be used to generate electricity.  This means that the only energy losses will be due to friction and generator efficiency.  Total plant efficiency, when utilizing cogeneration, can exceed 90%.

This turbine-generator power package, shown below, was built for a large Canadian electric company.  It is a horizontal steam turbine, type 24A, class 1, 25KW capacity, 3600 RPM, 150 PSI inlet, non-condensing, shown connected to a KATO AC generator, 600V / 3 phase 60 cycle class F, open drip proof construction.

Optional Generator Attachments

• Remote Analog Tachometer
• Bedplate to accept Turbine and Generator
• Automatic Voltage Regulator
• Power Isolating Transformer
• Units available up to 2.0 MW with steam pressures up to 600 PSI

Standard Features of Prime Turbines

• Simple design
• Easy operation and maintenance
• Positive overspeed trip
• Designed to NEMA and API specs
• Direct acting NEMA Class A mechanical governor (direct drive oil relay governor optional)
• For air, steam, or gas operation
• NEMA Class D Electronic or Mechanical Governors

    Factory assembled and included with our turbine-generator sets, these control panels are designed to meet common application requirements.  Custom control panels are also available to meet special requirements.

Generators and Governors

Generators

Induction

An induction generator is nothing more than an induction motor that is driven faster than its rated (synchronous) speed.  Because the generator is connected and synchronized to the grid, it resists the increase in speed, thus producing more energy than it would at its rated speed.  This extra energy is the electricity that comes from the generator.  Induction generators need to be connected to the utility grid in order to function - it is the frequency from the utility power that determines synchronous speed for the generator.  For this reason, induction generators are not suited for emergency situations when the utility power is unavailable.  However, due to their simplicity, they are ideal for use in cogeneration systems and peak shaving applications.  Induction generators are less expensive than synchronous generators, and it is often easier to receive utility approval for them.  Induction generators are typically seen in smaller applications, up to about 750 KW (1000 HP) and 13,800 Volts.

Synchronous

Though more expensive and complex, synchronous generators have many advantages over induction generators.  Most notably, these generators do not need to be connected to the utility grid in order to generate power.  Each generator is self exciting, and generates its own frequency.  In addition, synchronous generators are much more effective in applications with a higher power demand.  Because of their inherent properties, synchronous generators make ideal sources for backup power when the utility is unavailable.  Synchronous generators are also well-suited to general applications in cogeneration and peak shaving.

Synchronous generators require more complex setups and control interfaces, and must be carefully synchronized with the utility grid.  Utility approval for a synchronous generator may be more difficult to obtain than for an induction generator.

Governors

When a generator is operating while disconnected from utility power, the turbine's speed determines the frequency of the waveform of the electricity being generated.  In other words, the turbine's speed must be carefully controlled in order for useful electricity to be generated.  A governor is a device that monitors a turbine's speed and adjusts the amount of steam flow in order to keep that speed constant.

Woodward Mechanical Governors

TG Series (left) - NEMA A, direct acting or oil relay governor.  Ideal for non-frequency-sensitive applications and automatic start up operation.  Manual speed setting screw can be used to adjust load in parallel operation and frequency in non-parallel operation.

UG Series (right) - NEMA D mechanical governors suitable for frequency sensitive applications, such as parallel operation or load sharing, and both the UG-8 and UG-40 can be used for automatic start up operation.  Manual speed setting dial can be used to adjust load in parallel operation and frequency in non-parallel operation, and controls are available to remotely synchronize the turbine-generator in parallel applications.  The UG-40 is a higher force governor than the UG-8, and it is suited for use on turbines that have large inlet pressures and larger valve sizes.

Electronic Governors

Woodward 505 - Using either hydraulic or pneumatic actuators, electronic governors are well suited for complex applications, such as parallel operation with another turbine-generator set, parallel operation with power grid, load sharing, and automatic synchronization.  With powerful control software, the turbine can be monitored and controlled from a separate room, or on a personal computer or laptop.  The software graphically displays the data required for service and operation, and allows operators to input control commands.  The computer will also record turbine behavior, and is able to display the data to assist in maintenance and smooth operation.

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