Downdraft kiln fired with palm kernel shells

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This work was carried out to construct a downdraft kiln fired with palm kernel shells as an alternate fuel for firing clay bricks in a more efficient way. The work was a quasi-experimental involving the use of both qualitative and quantitative research methods. Interviews and participatory observation were employed to gather data for the study. Data was selected from a purposeful sample that was relevant to this study especially from heavy clay related areas. The study was in three different phase as part of it objectives. The first was the selection of four local soils which were tested be used for the production of insulating firebrick. They included: Mfensi ball clay, Mankranso ball clay, Tanoso ball clay and Kenyasi fireclay. They were mixed in batches and in ratios. Analysis from samples with code B3 and B-3 which represents a combination of 70% Mankraso ball clay with 30 % sawdust and 40% Mankraso ball clay, 30% Kenyasi fire clay with 30% sawdust showed a lower percentage with a total fired shrinkage of 1.67% and 1.0% respectively at 1050oC, compared to other body samples with lower percentage of sawdust which were also fired at the same temperature regime. The following tests showed that, sample with code B-3 with a batch composition of 40% Mankraso plastic clay, 30% Kenyasi fireclay and 30% sawdust which represent a ratio of 4:3:3 was ideal for production of insulating firebricks (IFB) in downdraft kiln linings at lower temperatures of 1050oC -1200oC. The second phase of this project was the construction of the downdraft kiln. Finally, test firing at 950oC showed no deformity in the kiln structure. Sample bricks fired with palm kernel shells showed three different characteristics. They were under-fired (salmon brick as generic word), over-fired brick (clinker brick) and well-fired bricks. These bricks were selected from four different locations in the kiln: the firebox area, the top (close to roof), middle and bottom areas. These were the results of the physical and mechanical analysis identified from the various test. The side wall brick close to the muffle wall or firebox showed the lowest water of absorption value of 4.5% whiles the brick from the bottom showed the highest water absorption with a value of 16.5%. The bottom brick achieved the lowest compressive strength of 10.0 and 18.0% as the highest value for the top brick which is close to the roof of the kiln. The study indicated that the bricks closer to the muffle wall although showed the lowest water of absorption came out as a defected brick. The bricks were glazed and melting because it had vitrified and almost turning glassy. The defect resulted in cracks and bloating of fired bricks.
A project report submitted to the School of Graduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfillment of the requirements for the degree of Master of Arts in Art Education