Research Information System
5th International Conference on Clean Coal Technologies, Zaragoza, Spain, 8 - 12 May 2011, (Full Text)
In this study, a low quality, high sulfur lignite coal was burned with olive cake and
wood chips in a laboratory scale circulating fluidized bed with secondary air
injection. The objective of the study was to optimize combustion performance, the
amount of the secondary air and the height where it is injected. Also, the second
objective was to see the longitudinal pollutant profile and understand the importance
of place and amount of the secondary air injection. The co-combustion
characteristics of these high-S coals with biomass were not investigated extensively
up to today.
A laboratory scale CFBC system was designed and installed for small scale tests.
The thermal capacity of the laboratory scale CFBC is 30 kW. The experimental setup
consists of a riser, a down comer, a fuel feeding system, electrical heaters, and two
cyclones. The lab-scale combustor column (riser) has an inside diameter of 108 mm
and a height of 6 m. It consists of 8 modules. The effect of staged air from six
different ports along the column on the emissions has been studied here.
The temperature of the riser column was kept at 850oC during the combustion
experiments. Combustion tests were carried out with Orhaneli lignite coal as the
main fuel. Olive cake and wood chips were used as the auxiliary fuel (biomass). The
fuel particles were between 1-2 mm. On-line concentrations of O2, CO, CO2, SO2
and NOX were measured in the flue gas and also along the height of the combustor
during combustion experiments. By changing the operating parameters (excess air
ratio, fluidization velocity, and fuel feed rate) the variation of emissions of various
pollutants were studied along the combustor.
During combustion tests, it was observed that the volatile matter from the biowaste
quickly volatilizes and mostly burn in the riser. The temperature profiles along the bed and the riser also confirmed this phenomenon. It was found that as the volatile
matter in the fuel mixture increases, CO concentration in the flue gas increases and
NO concentration decreases. Among NO, N2O and NO2 the most dominant
compound is NO. NO concentration is seen that it is not much affected by the SAR.