BC Hydro has purchased two 575-ton turbine hall cranes and one 30-ton construction crane from Konecranes America for its Mica hydropower station.
The Mica hydro station is located on the Columbia River about 135 km north of the city of Revelstoke. Mica currently operates with four generating units contained in an underground powerhouse that deliver a total output of 1,805 MW. The station was designed to hold six generating units, but only four were installed when the facility was constructed in 1977. The $700 to $800 million Mica Units 5 and 6 project will install the two remaining generating units, and add another 1,000 MW of power generation capacity.
The two new turbine hall cranes, designed to work in tandem to provide synchronized lifts up to 1,150 tons, will be the largest ever delivered by Konecranes in North America.
The massive double-girder cranes are cab-operated with radio backup, spanning 76 feet over the turbine hall on an 800-foot existing runway. Inverter-driven and AC powered, the cranes feature a PLC-based control system that monitors a load restriction path and the control synchronization system. The cranes will operate inside an underground chamber as the entire Mica facility is carved into a mountain. Access is via a 400-foot tunnel that gives trucks and personnel entry into the turbine hall.
According to Joseph Botros, Konecranes regional sales manager, a unique feature of this project is the challenge presented by installing the cranes – a challenge where Konecranes Nuclear Equipment & Services' proprietary technology developed for installations in the nuclear industry gave them a substantial edge in winning the order.
"Normal installation inside the underground facility using mobile cranes would be problematic –they wouldn't fit in the limited headroom without removing ceiling supports," said Botros. "Working with Konecranes Nuclear Equipment & Services we were able to utilize a brand-new technology they developed, and patented, in 2010 to make this challenging installation inside the cavern without removing ceiling supports or, most importantly, disrupting power generation."
Originally designed to complete complex installations at nuclear facilities, the patent pending Jacking Tower is delivered by tractor-trailers and assembled inside the cavern to the required height. The Jacking Tower rests on a base that allows for even load distribution, which is one large advantage over mobile cranes, whose tires have a very small footprint. Another advantage of the KNES Jacking Tower is the presence of a jib arm that can be utilized to raise and lower smaller loads. The Jacking Tower not only has the ability to remove all components from under the crane rather than above it also installs the cranes from below.
The Jacking Tower was developed by Konecranes Nuclear Equipment & Services' in-house engineering group in New Berlin, WI, and is the only one of its kind in the world.
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