Potential of community level utilization of coconut shell and stem wood for charcoal and activated carbon in Kerala

Abstract

Since the production of activated carbon at present being limited to large scale industries, an attempt was planned to develop an appropriate clean technology to produce activated carbon in the cluster or community based organizations. As the existing method of employing rotary kiln for the large industrial scale production of activated carbon has very little scope for down-scaling due to techno-economic considerations, fluidized bed reactor (FBR) system was identified as the appropriate technology for small or community level production of active carbon. Both the charcoal and activation plants were designed for continuous operation by way of operating three shifts per day. As pilot plants, a continuous vertical carbonizing plant with an input capacity of 3 tones raw material (coconut shell) per day, which can produce about one tone charcoal per day and an FBR with an input capacity of 0.25 tone charcoal per day, which can produce 0.125 tone of active carbon, was successfully designed, fabricated, installed, trial runs were conducted, optimized the process parameters for desired quality products, and assessed the quality of products for industrial use. The design drawings, description and operational details of the newly developed pilot plants are ready for commercialization. The quality of charcoal and the granular shell active carbon produced were found conforming to Indian standards. The details of the plants developed (1 tone output capacity charcoal plant and 0.125 tone output capacity FBR activation plant) as well as yield and quality assessments are given in this report. Economic analysis of the pilot plants developed showed that a minimum up-scaling of the plants to a level of a input capacity utilization of 6 tones of shells per day is financially viable for self-sustaining. Both the plants developed are pollution free and techno-economically suitable for cluster or community level production of charcoal and activated carbon after due up-scaling to the required capacity. As far as conversion of waste coconut stem wood is concerned, it was found that the plant can produce stem wood charcoal with moderate yield and quality. The inherent quality of stem wood charcoal, its poor hardness, makes it unsuitable for the manufacture of activated carbon. Stem wood charcoal is suggested for using as direct fuel or as an ingredient for fuel briquettes.