CFBC boiler is a brand new coal combustion technology with high efficiency and low pollution, whose features namely that there is a large amount of materials and supplies in the furnace which would be brought to the upper part by the flue gas during the combustion, then pass the separator at the outlet of the furnace. The mixture of materials and flue gas would be separated, at last materials and supplies would return back to the bed to perform circulating combustion by the non-mechanical loopback valve. Due to materials and supplies high concentration with large heating capacity, CFBC has large thermal capacity and can mix material uniformly; usually one kilogram of flue gas can carry over several kilogram of material. These circulation materials brings high heating transferring factor, which makes wide adjustment and range of boiler load and fuel. Fluidization speed of CFBC is higher than AFBC, so the bed area is not as apparent as AFBC . Because of strong turbulence and material circulation in the bed with lengthened burning time, CFBC has much more combustion efficiency than AFBC with no need to add assistant material.
The working temperature of CFBC is 850~950 C, which is a perfect temperature interval for desulfuring. This boiler uses the technology of desulfuring inside furnace, after refueling desulfurizer(e.g. limestone), fuel and desulfurizer would take low-temperature combustion and desulfurization reaction with strong turbulence. At this moment Ca/S mole ratio is 2 with 90% desulfuring efficiency and reduction of the discharge of SO2. CFBC adopts step blowing-in at low temperature, which makes burning at lower excess air all the time, so reduces NOx quantity. Moreover has high combustion efficiency, wide adjustment and range of boiler load and fuel, realizing complex utilization of ash and slag and so on. Due to above mentioned, CFBC boiler has been rapidly developed all over the world and it has been widely accepted that CFBC boiler is the most practical and feasible combustion equipment with environmental friendly so far.
Using matching and designing coal, this boiler could keep the rated parameters of outlet steam of superheater within the rated load range of 70-100%, when providing the constant pressure. And within the rated load range of 30-100%, this boiler could reach Stable combustion.
2 DESIGNING CONDITION & PERFORMANCE DATA
This boiler shall reside either indoor or semi-open-air. The mounting of this boiler combines suspension with sustaining with nominal height of operating floor--7m. This boiler utilizes single drum, natural circulation, concentrated down comers, balanced draft, heat insulating cyclone gas-solid separator, CFBC, convection heat surface arranged in convective pass.