Fuel, limestone and ash systems of fluidized bed boilers

In a fluidized bed boiler the fuel burns inside a bed of hot sand, ash and limestone kept in suspension by air blown from below; the limestone added to the bed captures part of the sulphur dioxide released during combustion. That is why limestone and ash systems are as much part of operating these boilers as the fuel itself.

Çankırı Saltı: boiler, fuel and ash handling systems (EPC)

Owner Medmar Tuz, EPC contract, period August 2021 – February 2023. Boiler: 44 t/h, 61.8 bar(g), 465 ± 5 °C atmospheric fluidized bed boiler, AFBC single drum. Technical data of the fuel and ash side:

• Total coal feeding capacity: 21,848 kg/h (8 feeders × 2,731 kg/h)
• Coal transfer: belt conveyor (50 m, 650 mm band) + 2 elevators
• Transfer rate: 30 t/h coal + 5 t/h
• Coal bunker: 235 m³ hard coal + 20 m³ lime
• Ash system: 1,200 kg/h; 3 screw conveyors + 1 bucket elevator

On site: from boiler erection to commissioning.

AKSA Göynük: limestone feeding from 75 to 110 t/h

Owner AKSA Göynük Enerji, turnkey contract, period May – November 2024. At the 2 × 135 MW plant, the limestone feeding capacity was raised from 75 to 110 t/h. Scope of work:

• Revision of the 800 mm limestone feed belt discharge chute
• 2 rotary feeders to feed both mills separately
• Raising the cones of 2 × 500 m³ silos by approx. 3.5 m, incl. seismic design
• Steel structure fabrication, erection, dismantling and testing

Enerjisa Tufanbeyli: coal chutes

Plant: 3 × 150 MW fluidized bed, location Tufanbeyli, Adana. Scope of work: revision works on the coal chutes of Units 1 and 2 of the plant. Coal chutes transfer the fuel from the feeding system to the boiler; clogging and wear disrupt the feed.