| OCR Text |
Show are urgently required to treat it. As for industrial waste liquids, drying and incineration is frequently applied for the method of reduction of the volume and solidification. In these processes, pretreatments that make the liquids chemically innoxious and stable are often necessary before the drying. Incineration may be a relatively convenient process because the liquids are not only burnt off but also inorganic components in the liquids can remain as the ash of simple compounds like oxides, sulfates, chlorides etc. However, some liquids generate pollutants when these are burnt, and they are emitted with exhaust gas. Moreover complete combustion is not always achieved unless properly operated. Hence the control of these problems is essential to develop an effective incineration process of waste liquids. Atomization of the liquid into a combustion flame of an auxiliary fuel is an available candidate for incineration of waste liquid. Because incineration of the small droplets m a y be effective. However, if the liquid includes volatile matters with only a low heating value or a large amount of unflammable component, the contact or mixing between the droplets and the combustion gas should be improved so as to achieve the complete incineration in a furnace. In this work, internally circulating particles are introduced in the incinerator. Generally, circulating particles promote heat transfer in a furnace because of interaction between gas and particles. It w as reported by Kataoka et al. [1] that the circulating particles contribute to the uniformity of temperature distribution in the riser, the enlargement of the flammable region and low N O x emission during the combustion of gaseous fuels. These characteristics may be applied to the incinerator of waste liquids. If the particles are appropriately chosen, removal of gaseous pollutant can be chemically realized. On the other hand, the selective non-catalytic NOx reduction (SNCR) is known as one of the N O x reducing techniques. The studies on this technique in the past are briefly summarized by Caton and Siebers [2]. Though ammonia has been the most representative reductant agent, urea is used as reductant agent in some studies [3-5]. The benefits of using urea are less odor than ammonia as well as relatively a harmless compound and low costs. The application of this technique to the incinerator may be effective in reducing NOx. |
