Fan Driver Options

As with pumps and most other mechanical drive equipment, ac electric induction motors predominate as fan drivers, and several effective control methods can be used with standard constant-speed electric motors. Speed control can also be achieved using variable-pitch belt drives, hydrokinetic and hydroviscous fluid drives, multiple-speed ac motors, dc drives, ac variable frequency drives (VFDs), and the three main classes of prime movers — reciprocating engines, gas turbines, and steam turbines.

Fans are generally not pre-packaged with prime movers because applications and equipment types are too diverse. However, once the requirements of the application are identified, packaging a fan with a prime mover is relatively simple and inexpensive. Similar to pumps, there are three common configurations: a single prime mover drive, a mixed system (or hybrid) set up using one fan and two drivers on a shaft, and a hybrid setup using two driver/fan sets. Following are a few examples of common applications for prime mover-driven fans.

Back-pressure steam turbines are economical for a variety of industrial applications and are often used as drivers for large capacity boiler fans. They are commonly applied in mixed system configurations, along with an electric motor drive.

Boilers are controlled by varying combustion air and fuel flow. The lower the airflow, the lower the firing rate or the greater the boiler turndown. Fan variable inlet vanes tend to flutter at low flow rates, and can thus limit boiler turndown in constant-speed applications. The combination of variable speed and inlet vanes may allow for a

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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