Crystal River power station is the largest power plant in Florida with a total generation capacity of 3,300 MW. The power station is located on the coast of the Gulf of Mexico in an area renowned for its great natural beauty and rich wildlife. Therefore, authorities have imposed strict limitations on the discharge of waste water from the plant.
The conventional wet sluice bottom ash removal system of Unit #2 (520 MW) used sea water and produced not only large quantities of contaminated waste water, but also caused several problems such as: heavy corrosion to the ash handling equipment and the lower boiler pressure parts, as well as refractory spalling in the water-impounded hopper. In addition, operating & maintenance costs for the complex system, with all its pumps, piping, dewatering bins and settling tanks, were very high.
The success of the MAC® (Magaldi Ash Cooler) systems in Italy convinced Duke Energy Florida to adopt Magaldi’s dry technology for the bottom ash retrofit of Crystal River Unit #2.



Duke Energy Florida, formerly Florida Power, was the generation, transmission and distribution sector of Florida Progress Corporation, the company that delivers electricity to Central and North Florida. In 2000 Florida Progress merged with Carolina Power & Light to form Progress Energy.
Then Progress Energy merged with Duke Energy in 2012. Today, the new Duke Energy Florida is the US’s largest utility. Their mission is to achieve more efficiency in delivering affordable, reliable and clean energy to approx.7 million Clients.



The configuration of the MAC® system for the Crystal River project is simple and effective: the MAC® conveyor extracts the ash from the bottom hopper and cools and transports it to the primary crusher before discharging it to the downstream pneumatic conveying system. The bottom hopper is equipped with a mechanical seal to compensate the boiler thermal expansions (downward and lateral), and hinged bottom doors (hydraulically operated), which provide an ash storage space in case of maintenance to the downstream equipment. This simple solution allows the completely dry extraction of the bottom ash in a completely dry way.
With the MAC® system, water consumption and waste water production are completely eliminated, as well as the need for the annual “patch and weld” of the previous system, drastically reducing related maintenance costs. Furthermore, the bottom ash was turned into a useful by-product for several applications. During boiler load peaks, the bottom ash production can vary greatly.
The MAC® extractor has proved itself to be very sturdy since it extracts ash rates as high as 30 t/h, even beyond the design previsions.
Another great advantage of the MAC® system is a continuous extraction of the bottom ash without intermediate storage in the bottom hopper, thus avoiding any potential risk of ash clogging in the hopper when high-slagging coals are burned. Moreover, the MAC® system operates in a fully automatic way and can be remotely controlled. After more than 20 years of continuous operation, the MAC® system is still running and providing these above mentioned benefits to the power plant.