STEEL BELT CONVEYORS FOR SEVERE CONDITIONS since 1929

BASIN ELECTRIC CORP.

THE CHALLENGE

In 2008, the Babcock & Wilcox Company awarded Allen-Sherman-Hoff, the USA Licensee for Magaldi Power S.p.A. technologies, with a contract to supply a dry bottom ash handling system for its new advanced pulverized coal fired boiler at Dry Fork power plant, owned by Basin Electric Power Cooperative.
The North Dakota-based power cooperative started construction in October 2007 and the dedication ceremony of the plant took place in August 2011. The new boiler, located 7 miles north of Gillette, incorporates the most advanced environmental control technologies. It burns the powder river basin (PRB) coal supplied from the nearby Dry Fork mine. The PRB is a high-slagging coal, producing high calcium content ash if compared to a bituminous coal ash.
Conventional wet bottom ash handling systems can be a concern in case high calcium content ash is produced: in fact, that kind of bottom ash can easily react with water, harden and build up in the handling systems. By completely eliminating the use of water and associated risks of ash conglomerations, the MAC® (Magaldi Ash Cooler) system dry technology becomes therefore the recommended solution for high calcium ash applications, ensuring continuous and safe transportation of the bottom ash to a storage silo.

 

THE CUSTOMER

Established in 1867, Babcock & Wilcox (B&W) is a global leader in energy and environmental technologies and services for power and industrial markets, with operations, subsidiaries and joint ventures worldwide.
The company is focused on the advancement of power generation efficiency: improvements in efficiency continue to help the power industry to use less fuel and produce lower emissions per kilowatt-hour of electrical output. Basin Electric Power Cooperative’s core business is generating and transmitting wholesale bulk electric power to Clients located in Colorado, Iowa, Minnesota, Montana, Nebraska, New Mexico, North Dakota, South Dakota, and Wyoming. Basin Electric owns 4,015 MW and operates 5,003 MW of electric generating capacity as of year 2015.

 

THE SOLUTION

The bottom ash that falls and exits the furnace through the refractory lined hopper is collected, air-cooled and transported by the MAC® system. The refractory lined bottom hopper is equipped with a mechanical seal, to compensate boiler thermal expansions (downward and lateral), and hinged bottom doors (hydraulically operated), which provide an ash storage space in the case of maintenance to the downstream equipment.
This simple solution permits the completely dry extraction of the bottom ash , with absolutely no use of water. After discharging from the MAC® extractor, the size of the bottom ash is drastically reduced through double roll crushers, thus enabling downstream pneumatic conveying of the bottom ash to a dedicated storage silo.

 

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