A trial of filter cake pellets and bagasse co–combustion in a sugar mill steam generator: Thermal and economical assessments

Abstract

Filter cake is a by-product from sugar production and estimated to be 4% of input sugarcane. The filter cake is a dark brown fine particle with 65%–75% moisture content. It is estimated to be 4 million ton/year in Thai sugar industry. This research shows a concept of turning this waste to energy by pelletisation and using the pellets as fuel in a steam generator. The pellets were co-combusted with bagasse in different ratios, i.e., 1%, 3% and 5% by mass. Combustion efficiency, outlet steam pressure and temperature were compared with the case of 100% bagasse. The results showed that 1% and 3% filter cake pellets gave approximately 91% combustion efficiency which is similar to the case of pure bagasse. However, when using 5% pellets the combustion efficiency dropped to 87% due to feeding system problem. It was suggested that fuel spreading system must be modified when using 5% or higher ratio of the pellets. Moreover, outlet steam temperature and pressure were almost the same for the case of pure bagasse compared with the case of 1% and 3% pellets co-combustion. It reveals that filter cake pellets can be utilised as fuel without any problem, and this is a way to support the zero-waste campaign in sugar industry.