Design, construction and test operation of a thermal incinerator for medical wastes at Abokobi Health Centre, Ghana

Abstract

The primary factors considered in the design and construction of a modified De-Montfort type intermittent incinerator for combusting medical wastes were the waste types, fuel, chimney size, and flue gas residence time. The design analysis was based on flue gas flow rate of 0.13 m³/s, maximum primary chamber temperature of 870 °C and minimum ambient temperature of 27 °C. The total flue gas residence time of 6.9 s was achieved for the three chamber system of 0.9 m3 total volume. The medical wastes generated from the four medical facilities in Ga East District (Ghana) consisted of infectious sharp objects, syringes, wound dressings and gloves; which were incinerated at a throughput of 80 kg/day with destruction efficiency of 98.47 %, using fuelwood as primary fuel. The natural convection thermo-fluid flow was controlled by ambient wind speed of ~ 3.8 ms-1, at temperature of 31.5 °C. The primary combustion chamber temperature attained was ~ 516 °C, while the third chamber temperature reached 760 °C, which ensured complete combustion of the wastes with reduced particulate matter emissions. At optimum operating capacity of 0.6 m3, up to 4 cycles of incineration were done in a day, each cycle lasting about 80 minutes.