Basic study on combustion characteristics of waste rice husk and emission behavior from a new-type air vortex current combustor
There are large quantities of rice husk estimated around 3 million tons as agricultural waste every year in Japan. Air pollutants emitted from exhaust gases of rice husk incineration lead to very important environmental damage, not only because of the influence on global environment and climate, when released into the atmosphere, but also on human health due to the local air pollution. Therefore, it is necessary to effectively utilize the rice husk waste and to reduce the air pollution. We try
... o develop a new-type air vortex current small-scale combustor which can effectively combust rice husk as biomass energy instead of fossil oil fuel for farming-greenhouses heating during the winter season. In this study, we investigated if rice husk can be fed on the new-type air vortex current small-scale combustor and reduced fossil fuel. The new-type small-scale combustor is able to keep a constant high temperature (about 1000°C) even if the rice husk combustion is not under the best conditions. At the same time, it is also important to evaluate the emission behavior of harmful air pollutants emitted from the rice husk combustion with measuring carbonaceous and ionic composition of suspended particulate matter (SPM) in the exhaust gases from the new-type air vortex current combustor, and to reduce the pollutant emission by controlling the combustion conditions. From the analytical results of the size distribution of carbonaceous composition collected by an air sampler, it is shown that elemental carbon dominated in the coarse Sustainable Chemistry 199 www.witpress.com, ISSN 1743-3541 (on-line) WIT Transactions on Ecology and the Environment, Vol 154, particles, which are produced by incomplete combustion, and organic carbon dominated in the fine particles. Carbonaceous concentrations can be reduced substantially in the emitted particles by highly effective combustion when the combustor was improved. As the results of the ionic composition, high concentrations of potassium ion as a tracer of biomass burning were determined. Combustion temperature control is important to avoid corrosion in the system and the health effects from high concentrations of chloride contents. Although the new-type air vortex current combustor developed in our purpose is typically small-scale, however, usual fixed-bed combustors are prone to be incomplete because of the simplicity of the structure. Since there are no specific regulations for these kinds of combustors in Japan, therefore, even small combustor fall out of the possibly applicable emissions regulations, to ensure stable combustion performance and less air pollutants. In near future, we try to improve the combustor fed with less fossil oil fuel and more rice husk waste which will be feasible and sustainable.