Calorific values of South African Bagasse

Proceeding of the South African Sugar Technologists Associations 01/1977;


When gross calorific values (GCV's) on a moisture-free, brix-free and ash-free basis were determined on varieties of S.A. bagasse, no significant differences were found when age, time of harvest, source, fibre, pith, cane stalk or cane tops were considered. Only cane leaves gave higher values. Since ash exerts a significant influence, a formula including ash % sample as an independent variable was developed to predict the GCV. Using a hydrogen content of $91 % (dry basis) for bagasse, an equation to predict net calorific value (NCV) of bagasse was developed which also includes ash % sample as an independent variablle. The equation predicts NCV defined at 20°C.

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    • "• The diffuser produces slightly more bagasse than the milling train, firstly because of lower loss of suspended solids in mixed juice (typically 0, I% versus 0,7%) and secondly because of the lower bagacillo requirement (0,5% versus 1,0% on cane). • Due to the higher ash content of the diffuser compared with milling, (typically 3,5% versus 2,0%), the diffuser bagasse has a slightly lower heating value (7205 versus 7500 MJ/t NCV), per formula of Don et al. (1977). However, the combined effect of all this is that the total bagasse from a diffuser has a slightly higher heat content. "
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    ABSTRACT: The energy requirements for a diffuser versus a milling factory are compared by means of a computer simulation program. Generally, the diffuser option requires more steam, except for the case of low pressure boilers. The diffuser op­ tion gains strongly when export power is to be maximised. When Vapour 2 instead of Vapour 1 is used for diffuser heating and pan operation, there is little difference in the total high pressure (HP) steam consumption.
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    ABSTRACT: The bagasse is the only fuel used in the sugar - alcohol industry in Brazil, the biggest producer of sugar cane in the world. The sugar - alcohol industry produces, by cogeneration, electric energy for its own use and for selling. The improvement of the use of bagasse in the furnaces is an important industrial strategy nowadays. This subject has become of great interest due to the increasing of cogeneration level in the last years. The state of art of sugar cane bagasse drying is presented here. This work shows an improvement of the steam system efficiency due to sugar cane bagasse drying. However, a trade off between the energy used to dry the bagasse and to pre-heat the boiler combustion air is necessary. Two types of air heater - dryer arrangement were studied: the first one consists of a series arrangement and, the second, of a parallel arrangement.
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    ABSTRACT: Two boiler designs have recently emerged to suit the present requirements of the cane sugar industry, viz the single pass panel wall unit and the three pass, bottom supported boiler with an open pitch furnace tube construction. The former is less susceptible to erosion compared with the original concept of the three pass boiler. It is believed that the three pass unit in its present form as installed at Tongaat will be effective in reducing erosion in the tube bank. The effect of fuel properties on the performance of boiler plant is considered and it is shown that efficient operation, in addition to improving the utilisation of bagasse, can result in a significant reduction in tube erosion. A relationship is presented for determining dust loadings as a function of the grate heat release rate and the fuel ash content at the furnace and main bank exits. Circulation studies un- dertaken on both boiler types are presented indicating very similar circulation rates. Shrink and swell characteristics and hence the drum level stability can be related to the volume of water contained in the system and the water plan area in the drum at the steam - water interface. Finally the mechanical design features of the two boiler designs are compared to pro- vide an insight into the design philosophies relating to the two units.
    Preview · Article · Jan 1977
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