Design of Fluidized Bed Bagasse Gasifier (A Case Study For Fincha Sugar Factory)
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Date
2013-04
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Addis Ababa University
Abstract
With increasing demand of energy and global issue of sustainable energy resource of the
world, energy from Biomass is attracting the attention of many researchers as a source of
energy in the world.
Currently in Ethiopia about nine new sugar factories are being installed requiring adequate
amount of electrification and energy. The demand of these industries can be met from
different sources of energy. Gasification can be considered one of these sources.
In this work an attempt has been made to develop a procedure for designing a fluidized bed
reactor that can handle bagasse as a feedstock. By using an appropriate design
procedure a complete design of a gasification reactor was studied deeply. The design
procedure followed in this thesis is presented in Appendix III.
The design work has been categorized into three different parts. The first one deals with the
equilibrium modelling of the fluidized bed to determine the output gas composition. The
equilibrium model is analyzed with the help of a matlab code giving the volumetric/ molar
composition of the product gas. The higher heating value (HHV) found is 2.69 MJ/kg with
the moisture content of 15%. A thermal efficiency of 50.78% was obtained which would have
reached about 80% if the sensible heat of the product gas was put under consideration. The
second part of this design work aims at determining the appropriate fluidization parameter of
the reactor since efficient fluidization is required for effective reaction and maximum output
efficiency. Parameters like the minimum fluidization velocity, the terminal fall velocity, the
operational velocities and the bed and freeboard geometries have been determined. The third
part of this design work investigates the dimension of the reactor, its insulation and the
openings of the shell and other components of the reactor. The reactor has a 4.2 m outside
diameter by 11.3 m height.
Finally an economic analysis was done on the cost of the gasifier which compares natural gas
use as an energy source. The configurations of the reactor and the distributor of the reactor
are also the core focus of the design work.
Key words: Biomass, gasification, producer gas, Thermal efficiency, fluidization, higher
heating value.
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Keywords
Biomass; gasification; producer gas; Thermal efficiency, fluidization; higher heating value