Design Improvement of the Philrice Continuous-Type Rice Hull Carbonizer for Biochar Production towards Sustainable Agriculture
14 Pages Posted: 23 Dec 2012 Last revised: 24 Jan 2013
Date Written: December 23, 2012
The use of biochar from rice hull (carbonized rice hull) is becoming popular among Filipino rice farmers particularly those practicing an integrated system of farming locally called as Palayamanan. Under this system of farming, carbonized rice hull is widely used as soil conditioner or as main ingredient in the production of organic fertilizers. Some farmers are also using it as animal bedding to absorb urine and fresh manure. The saturated biochar are then incorporated into the soil as organic fertilizer for vegetables and other crops. With this practice, farmers not only were able to save on fertilizer but also reduce their carbon footprints thus contributing to the global effort of reducing the greenhouse gas in the atmosphere. While the PhilRice-developed continuous-type rice hull carbonizer has been successfully used in the production of biochar for various uses in the farm, there were some weak points and operational concerns that were revealed only after its continued use. The major one is when operating during windy conditions wherein there were significant dusts and smoke emissions generated which exposed the operator to health hazards. Hence, the design was further improved. To further enhance the usefulness of the equipment, design improvements were also geared towards making it able to process biochar from other agricultural wastes that are commonly generated in the farm. Moreover, design refinements were also done on reducing its material and manufacturing requirements in preparation for its possible commercialization. The resulting improved prototype is flat sided which make it simpler to fabricate, incurring less material wastage, than the previous one. The flat sides makes use of 2mm thick metal sheets and their dimensions (0.8m x 1.2m) were chosen in such a way that no waste cuts are left from the two sheets (standard size: 1.2m x 2.4m) used. Unlike in the previous prototype where a side opening was provided to facilitate manual agitation of the rice hull bed, the improved prototype features a fully enclosed hopper. In terms of the cost of fabrication materials used the improved prototype costs 28.8% lower than its predecessor. Test runs conducted showed that the improved prototype can operate under windy conditions with no significant effect on emission. In most cases (at least 85% of the time), the prototype operates with clear emission at the chimney. Input capacity ranged from 20.6 to 36.2 kg/h with biochar recovery of 37.3 to 40.5% (by volume), depending on the condition of the rice hull and the frequency of collecting the processed biochar, among other factors. The prototype has been tested with and found to be able to process other agricultural wastes such as rice straw, small branches of trees, and coconut husk into biochar.
Keywords: Biochar, Biomass, Carbonized Rice Hull, Rice Hull, Rice Hull Carbonizer
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