Gasification of tea (Camellia sinensis (L.) O. Kuntze) shrubs for black tea manufacturing process heat generation in Assam, India

Gasification of uprooted tea shrub (Camellia sinensis (L.) O. Kuntze) is an attractive option for partial substitution of thermal energy in tea manufacturing industries. Chopped and dried uprooted tea branches with moisture content (X < 20%) have high energy contents suitable to generate process heat. Good number of tea processing units in Assam use old design and inefficient coal fired furnace and air heater with a low overall efficiency. Gasification of uprooted tea shrubs may be beneficial partially to substitute these old design coal fired furnaces. The calorific values of uprooted tea branches and generated producer gas were found 18.50 MJ kg(-1) and 4.2 MJ m(-3), yielded products at 65% cold gasification efficiency. Fermented tea samples with an average moisture content of 60% could be dried to 3% moisture using biomass gasifier and tea dryer setup. Simple economic analysis shows gasifier cum tea dryer technology may be economically favorable option with an annual saving of 21,067 $ in a medium scale tea factory (990 t per year made tea) if 28% of total thermal energy requirement is substituted by biomass gasification. (c) 2014 Elsevier Ltd. All rights reserved.