STEEL BELT CONVEYORS FOR SEVERE CONDITIONS since 1929

STX Heavy Industries

THE CHALLENGE

Bukpyeong Thermal Power Plant (2x595 MW ultra supercritical units), located in the Bukpyeong National Industrial Complex, Donghae City, Gangwon Province (Korea), was the first privately funded investment project in South Korea. The plant owner STX Electric Power entered into a joint venture with Korea East-West Power. STX EP was responsible for the construction and operation of the power plant, while EWP was in charge of management, handling and maintenance. Both STX EP and EWP held a clear vision: simply to make Bukpyeong TPP the most environmental friendly power plant project in South Korea. Thus, Bukpyeong TPP looked with extreme interest at the application of Magaldi technologies in order to extract the bottom ash in a dry way and turn it into saleable fly ash.
After more than two years of detailed negotiations, in June 2013 BHI awarded to Magaldi Power S.p.A. the contract for the design and supply of two MAC® (Magaldi Ash Cooler) and MAR® (Magaldi Ash Reciycling) systems for the Bukpyeong power plant project. At the Bukpyeong power plant, the bottom ash will no longer be considered a coal combustion waste but a useful secondary raw material.

 

THE CUSTOMER

The Korean BHI is a global power plant equipment supplier that owns environmental-friendly and high-efficiency technologies minimizing carbon emission and maximizing energy efficiency. BHI provides services for engineering, manufacturing, construction and erection based on global experiences, technology and professionals. Their business spreads from power plants to steel plants, oil & gas refineries, civil engineering, construction and erection. Their main products for power plants are PCF boilers, CFBC boilers, oil & gas boilers, surface condensers, CCW heat exchangers, HP & LP feed water heaters.

 

THE SOLUTION

The MAC® and MAR® systems extract, dry cool, grind and convey the bottom ash up to a storage silo. From that silo the dry bottom ash is recycled to the boiler furnace through the coal mills or discharged onto open trucks. The MAC® and MAR® systems are connected to the boiler through a mechanical expansion joint, which assures a sealed connection between the boiler and the bottom ash hopper.The bottom hopper, refractory lined and thermally insulated, is equipped with hydraulically-operated bottom doors.
The MAC® extractor conveys and cools the bottom ash using a controlled amount of ambient air that enters the conveyor casing thanks to the negative pressure prevailing in the boiler. The air flow cools the ash along the conveyor and reaches the combustion chamber recuperating a considerable amount of energy from the bottom ash. As a result, cooling air enters the furnace through the boiler throat at quite a high temperature, receiving a significant amount of energy in the form of ash sensible heat, ash chemical energy from unburnt particles and boiler radiation flux through the throat. After discharging from the MAC® extractor, the bottom ash is reduced to approx. 25mm grain size by single roll crushers. Downstream the crushing stage, the bottom ash is further cooled in the Postcooler conveyor and then discharged into the storage silo.
The silo is equipped with 2 exits: one for wet discharge of the bottom ash onto open trucks and one for dry discharge of the bottom ash to be recycled to the boiler combustion chamber. In the MAR® system the bottom ash is pulverized to approx. 5 mm grain size by a hammer mill and then pneumatically conveyed to the reception bins located in the boiler house close to the coal feeders. The bottom ash is finally dosed to the coal mills and conveyed by the primary air to the boiler combustion chamber where it is turned into fly ash.

 

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