Development of Small Scale Palm fruit Biomass-Fired Boiler
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Date
2011
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Publisher
Obafemi Awolowo University
Abstract
This study characterised palm fruit biomass for proper selection as fuel. It designed a boiler to utilize the fuel and evaluated the boiler for its performance. This was with a view to providing appropriate technology for small scale palm fruit processing.
Fresh fruit bunches (FFB) were processed to obtain the required waste products and the wastes collected were sun-dried to constant weight. Fuel properties such as the moisture content, bulk density, ash content, volatile matter, fixed carbon content and the calorific value were determined at interval of 3 days. Boiler parts like the furnace, boiler drum, water and fire tubes were designed based on the quantity of steam required to process 0.25 ton ffb/hr (i.e. 150 kg/hr). The volume of the furnace was determined based on the quantity of fuel required to deliver 70% efficiency of the boiler. The furnace was double walled with the inner wall made of kaolin (pure white clay) brick while the outer wall was made of clay laterite. The boiler was evaluated for its fuel consumption, steam production rate and efficiency using 100 kg of different fuel samples (shell, palm fibre, empty fruit bunch (efb) and wood) with known calorific value and their combinations for a period of 60 minutes firing time.
Result showed that moisture content of the wastes exhibited direct relation with the bulk density and the volatile matter, as they decreased with decrease in the moisture content. On the other hand the calorific value, fixed carbon content and the ash content exhibited an indirect relation with the moisture content. These parameters increased as their moisture contents decreased. The moisture contents of the shell, fiber and efb decreased from 31.16 to 6.58, 49.46 to 3.32 and 57.37 to 7.71%, respectively, while the bulk densities reduced from 0.31 to 0.28, 0.15 to 0.08 and 0.31 to 0.08 g/cm3, respectively, in that order. Also the ash contents of the shell, fibre and efb increased from 6.55 to 12.67, 3.46 to 8.27 and 5.18 to 16.46%, respectively, while the volatile matter decreased from 81.39 to 73.59, 87.17 to 77.15 and 84.60 to 62.80%, respectively. The fixed carbon contents increased from 12.065 to 13.747, 9.363 to 14.58 and 10.22 to 20.74%, respectively, and the calorific values increased from 10.87 to 14.94, 7.57 to 16.45 and 5.57 to 13.99, respectively. The effect of drying was observed to significantly (p<0.05) affect the fuel properties of the palm fruit waste. The rate of fuel consumption by the furnace differed with the type of fuel materials as 100 kg of shell and 100 kg of wood burnt within 55 minutes firing time while the combination of shell and wood burnt within 60 minutes of its firing time under the same condition. Combination of shell and efb lasted for 50 minutes during firing while efb alone burnt completely within 35 minutes. The highest quantity of steam (17.99 kg/min) and maximum boiler efficiency (79.6%) were recorded when fired with efb only while 10.96 kg/min steam production rate and 76.4% efficiency were recorded when fired with shell and efb combination. Combination of shell and wood produced 10.31 kg/min of steam and 76.6% boiler efficiency while 11.31 kg/min of steam and 76.9 % boiler efficiency was obtained using wood only. Combination of shell, efb and fibre gave 15.28 kg/min of steam and 73.1 % boiler efficiency while 10.32 kg/min of steam and 76% boiler efficiency was obtained using shell only. The effect of fuel material was found to significantly (p<0.05) affect the steam temperature, vapour pressure and enthalpy.
The study concluded that the boiler developed using adequately-prepared locally-available materials has the potential to be incorporated into the small scale palm fruit processing technology profile and at the same time there is opportunity for improving its performance.
Description
Pages 103,xviii
Keywords
Small Scale, Palm Fruit, Biomass-Fired Boiler, Fresh Fruit Bunches, Technology
Citation
Yusuf Adeshina Salako(2001)Development of Small Scale Palm fruit Biomass-Fired Boiler