AN INTEGRAL APPROACH TO EVALUATE THE PERFORMANCE OF BAGASSE CO-GENERATION PLANTS

摘要

Bagasse cum coal co-generation plants, in partnership with the cane sugar industry of Mauritius have become major players in the electricity production sector. In the larger plants, coal is used as fuel during the off-crop season to enable electricity export all year round, ensuring optimal plant operation and profitability. In the year 2003, power sales to the utility, using bagasse and coal as fuel was around 300 GWh and 430 GWh, respectively. The development phase is approaching completion, and the energy optimisation stage has started. In our quest to optimise the technical performance of bagasse co-generation plants, the factors influencing surplus electricity production were analysed, using existing data. It appears that the large disparity between the electricity production of the least and the most efficient co-generation plants is not solely a matter of technological superiority, e.g., high-pressure boilers. The turbo-alternator, process steam consumption, imbibition % cane, fibre % cane, boiler efficiency, moisture % bagasse, electricity consumption in the mill and in the power plant have distinct influence on surplus electricity production. Consequently, the performance of a co-generation plant can be accurately assessed only when all these factors are considered integrally and referred to a benchmarked figure for comparison. Energy inefficient areas can be detected for remedial action to be taken. Electricity production and sugar recoveries are technical indicators for this performance evaluation. Typical figures from Mauritian co-generation plants are used to benchmark the surplus electricity production for plants with low, medium and high-pressure boilers. Achievable targets with proven technologies show that it ranged between 76 kWh/t cane to 143 kWh/t cane (433 to 815 kWh/t fibre) from the low-pressure to the high-pressure boiler range.