Cost-effective cassava processing: case study of small-scale flash dryer reengineering

This chapter describes the development and scaling-out of flash dryer innovations for more efficient, small-scale production of high-quality cassava flour (HQCF) and starch. The diagnoses of cassava-processing SMEs (small and medium enterprises) revealed their energy expenditures for drying were considerably higher than those of large-scale industrial companies, which was mostly due to sub-optimal design of flash drying systems. As a result, small-scale production of cassava starch and HQCF often incurs high production costs, incompatible with market prices of final products. Taking stock of this situation, RTB scientists have developed several innovations to optimize energy efficiency and costs, including a longer drying pipe, re-engineered heat exchanger, larger blower for higher air velocity, and a higher product:air ratio. This was based on numerical modelling to determine the key design features of energy-efficient flash dryers, followed by construction and demonstration of a pilot-scale prototype. As a result, improved small-scale flash dryers are now being scaled-out to the private sector in various countries, using the Scaling Readiness framework and achieving 10-15% gains in productivity and incomes. A method for diagnosis of process efficiency is also described, to identify technical bottlenecks and to document and measure the outcomes and impacts during the implementation of scaling-out projects