الفهرس 
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Abstract
Abstract
The present study investigates the combustion of four kinds of biomass in a
circulating fluidized bed (CFB) system located in Faculty of Engineering, Minia
University. The aim of this study is offering the optimum experimental conditions for
straw, saw dust wood, cotton seeds burs and corn stalks combustion in CFB combustor. In
addition, the study investigates the effect of changing the equivalence ratio (Ô) on the
temperature distribution, emissions, and heat flux inside the combustion chamber.
The test rig consists mainly of the circulation system, the fuel supply system, and
the air supply system. The circulation system consists of the combustion chamber, the
connecting pass and the cyclone. The combustion chamber consists of the reactor and the
air distributor. The reactor is a steel cylinder with 145 mm inner diameter, 2000 mm height
and 12 mm thickness. The furnace is warm up by the combustion of the commercial butane
gas (Butagas).
Every kind of the used biomass is burned with different values of
equivalence ratio. The temperatures and heat flux are measured along the reactor. The
emissions of CO, NOX and SO2 are measured in mg/Nm3 in flue gases along the reactor
and at the chimney. Finally, a comparative study between the combustion of the four kinds
of biomass was obtained.
It is concluded that there is a general stable trend of the temperature across the
horizontal sections and along the combustion chamber for all used biomass except for the
cotton seeds burs combustion. The admission of the first secondary air reduces the
temperature for all used biomass except for the cotton seeds burs combustion. The second
secondary air raises the temperature above its admission level for cotton seeds burs and
corn stalks combustion. However, it has no obvious effect on temperature in case of straw
and saw dust wood combustion. The highest temperature level occurs at Ô=1.24 except for
corn stalks combustion where it occurs at Ô=1.4. Straw verifies the highest temperature
(1080 ˚C) for all used biomass. The corn stalks combustion achieves to the highest flue gas
temperature (about 350 ˚C). The maximum temperatures inside the reactor and at the
chimney occur with equivalence ratio of 1.24.
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The maximum and minimum values of heat flux along the combustion chamber are
55 kW/m2 and 7 kW/m2 respectively. Saw dust wood produces the highest values of CO
emissions (about 3000 mg/Nm3). Cotton seeds burs produce the lowest values of CO
emissions (about 250 mg/Nm3). The secondary air minimizes CO and NOx emissions for
all combusted biomass. SO2 emissions are under the German standard limit. The lowest
values for emissions occur at Ô=1.24 equivalence ratio except for cotton seeds burs
combustion where the minimum values are at Ô=1.4.