such as charcoal density or specific gravity, volumetric shrinkage,
gross heat of combustion, crushing strength, porosity, and dynamic elastic modulus and internal friction.
In addition, the charcoal quality is also evaluated by chemical composition which includes carbon, hydrogen, oxygen, nitrogen and sulfur contents determined by ultimate analysis, and the amount of fixed carbon, ash and volatile matter contents determined by proximate analysis.
In Egypt , palm fronds are used as a source of energy by direct burning specially in the remote areas in the western and eastern deserts as well as in villages.
Converting palm fronds is not a common practice in Egypt and nothing has been carried out relevant to converting palm fronds into charcoal. In South East asian countries, the stems of oil and coconut palms are widely used in charcoal production.
At Ei-Wadi El-Gadid zone, the problem of frond wastes has appeared durin9 the manufacture of palm fronds into blockboards (lumber-core plywood). Using the solid residues of fronds for charcoal production represent one of the proposed ways to solving this problem.
The objectives of this study is to produce charcoal from palm fronds and to evaluate the properties of produced charcoal which determine its quality.
Experimental
The specimens were taken from three species growing in Aswan governorate. These species are Balady, Sakkoty and Zokor. Three fronds of three palm trees from each species were taken for specimen preparation. Three sticks with dimensions of 1 x 1 x 1.0 cm were removed from three zones along the frond: base, middle and top. The sticks were subsequently cross cut into cubic specimens. The specimens were oven-dried and the oven-dry weight was recorded.
For specific gravity of fronds and apparent density of the resultant charcoal, the volume was measured by immersion in mercury using Amsler volume-meter.
The carbonization (charcoaling) was done using tube furnace in a flowing nitrogen atmosphere at terminal temperature of 500°C with a holding time of 2 hours and a heating rate of 5"C /min. The nitrogen flow rate was adjusted at 300 rnl/min.
The charcoal yield was calculated as a percentage of oven-dry weight of charcoal specimen to oven-dry weight of original palm frond specimen.
Specific gravity of specimen before charcoaling as well as the apparent density of the resultant charcoal was evaluated also based on oven-dry weight and oven-dry volume of charcoal.
Gross heat of combustion of charcoal was determined using an adiabatic oxygen bomb calorimeter. Parr 1341 . According to procedures recommend by the Parr instruction manual and in accordance to the ASTM, D2015-85(1987)2.
Moisture content, volatile matter content, and ash content were determined according to the ASTM, D-1762-84(1989)3 for chemical (proximate) analysis of wood charcoal.
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Results
Table 1 represents the average of different quality parameters of charcoal produced from palm fronds compared to the charcoal produced from casuarina wood which represent the common species for charcoal production in Egypt . From the table, it is clear that, the quality of charcoal produced from different zones along the frond had nearly same parameters except in ash content and fixed carbon content where the ash content decreased and fixed carbon increased by Increasing height along the frond.
It is known that, the quality of charcoal increased, by increasing the gross heat of combustion, apparent density and fixed carbon content, and by decreasing volatile matter and. ash contents. Therefore, the charcoal produced from the midd-le and top of frond is generally better in its quality than that produced from the base of the frond. This is due to its lower content of ash and higher fixed carbon content.
Comparing the quality parameters of the charcoal produced from palm frond with casuarina charcoal, it is clear that palm frond charcoal, irrespective of the yield and volatile matter content, is generally lower in its quality than casuarina charcoal at nearly the same carbonization conditions. This is due to its higher contents of ash (14.43%), and lower gross heat of combustion (6100 cal/g), and lower fixed carbon content (62.24%). Nevertheless, the palm frond charcoal is similar or of better quality than tamarisk charcoal 4 .
These results indicated that, charcoal of acceptable quality under Egyptian market can be produced from palm fronds, specially the upper part of the frond. Using this charcoal in specialized industrial uses is not recommended due to its higher content of ash, fixed carbon and lower value of gross heat of combustion.
Table 1. Mean Values* and standard deviations** for specific gravity (EG) of frond. Yield, Apparent Density (DC), Gross Heat of Combustion (GHC), Ash Content (Ash), Volatile Matter Content (VM), and Fixed Carbon Content (FC) of Charcoal Made of palm fronds and from Casuarina***.
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*Each value is an average of 10 specimens. Means with the same letter are not significantly different.
**Values in parentheses represent standard deviations.
***The indicated means were extracted from M. Sc. Thesis3 under carbonization conditions of 450°C maximum final temperature, 10°C/min heating rate and 120 min residence time.
1 This part of work was carried out at Wood Technology Lab., Dept of Forestry and Wood Technology, Faculty of Agriculture, Alexandria University by Dr. M. M. Megahed.
2 STM. D 2015-85. 1987. Standard test method for gross calorific value of coal and coke by the adiabatic bomb calorimeter. Philadelphia , Pa. U.S.A.
3 ASTM. D 1762-84. 1989. Standard method for chemical analysis
of wood charcoal- Philadelphia , Pa. U.S.A.
4 Hendi, S.S.Z. 1994. Charcoal properties as affected by raw material and charcoaling parameters. M. Sc. Thesis, Faculty of Agriculture, Alexandria University , 96p.
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