STEEL BELT CONVEYORS FOR SEVERE CONDITIONS since 1929

COMPLEXUL ENERGETIC OLTENIA

THE CHALLENGE

Within the framework of a modernization program, Societatea Complexul Energetic Oltenia S.A. (CE Oltenia) was looking for a system able to reduce CO2 emissions and improve the boiler efficiency at Isalnita Power Plant, in Romania.
CE Oltenia signed a contract with GE Power Romania for the retrofit of the existing wet bottom ash handling system (submerged chain conveyor - SCC) with a new dry system, on a turn-key basis. GE Power Romania choose in turn Magaldi’s dry bottom ash handling technology, able to reduce the unburnt particle in bottom ash, decrease emissions and increase the boiler efficiency together with the overall dependability of the unit.

 

THE CUSTOMER

Societatea Complexul Energetic Oltenia S.A. (CE Oltenia) is the sole lignite producer in Romania and one of the major players in the energy services sector.
It was set-up in 2012 following a decision of the Romanian Government for the reorganization of the energy sector through a merger between a national lignite company (Societatea Nationala a Lignitului Oltenia) and three energy producing companies (Complexul Energetic Rovinari, Complexul Energetic Turceni and Complexul Energetic Craiova).
CE Oltenia has an installed production capacity of 3900 MW thermal. The main raw material used for the production of electricity is lignite extracted from Oltenia basin.

The Işalniţa Power Station, operated by CE Oltenia, is a large lignite-fired thermal power plant located in Işalniţa - Dolj County. Four boilers are connected to two generators of 315 MWe each, for a total of 630 MWe of installed capacity.

 

THE SOLUTION

Burning lignite, the combustion process generates a content of unburnt fuel in the discharged bottom ash with high heat content. In order to recover the ash sensible heat thus improving the boiler efficiency, GE Power chose the MAP® (Magaldi Ash Post-combustor) system to retrofit Unit 7, replacing the existing wet bottom ash handling system (Submerged Chain Conveyors – SCC).
As a development of the MAC® (Magaldi Ash Cooler) system, the MAP® is able to extract, convey and cool bottom ash in a dry way and to enhance and control the post-combustion (PCB) of unburnt particles on the steel belt (Superbelt®).
Magaldi’s proven dry bottom ash handling technologies help to marginally improve the boiler efficiency, allowing a reduction of the UBC (Un-Burnt-Carbon) content in the bottom ash, recovering chemical energy back to the furnace and eliminating any use of water as bottom ash cooling and conveying medium.

The revamping will start below the existing boiler transition chute where the MAP® conveyor will be installed. Bottom ash falling from the transition chute will be collected and dry conveyed allowing to continue the combustion process. On the contrary, with the wet system, the combustion is immediately interrupted when ash falls into the water basin. 
Thanks to a proper regulation of air flow and temperatures, the MAP® system will ensure the PCB control. In particular, the design with slots on the Superbelt® optimizes the air flow through the ash and allows oxygen to reach the hot residual carbon particles in the ash.

The MAP® is designed for an UBC content reduction ranging from 15% up to 40%, corresponding to a significant generation of energy on the belt.
Thanks to a strong UBC content reduction obtained by the post combustion of the bottom ash on the Superbelt®, the MAP® system will be able to recover and send back to the boiler all the chemical energy contained in the bottom ash. Energy that is presently lost in the water bath of the SCC. The MAP® system leads to a substantial boiler efficiency increase which in turn will imply a reduction of GHG emissions.

The rehabilitation of old wet bottom ash handling systems is nowadays promoted in Countries where lignite is still produced at a high rate, due to its low cost, like in Romania. In these Countries, the MAP® system represents the best and environmental friendly choice to improve the plant efficiency.

 

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