Black liquor: predicting droplet size from black liquor spray characteristics.APPLICATION: The ability to predict the final drop size from spray properties makes it possible to better control the location of the combustion processes and char-bed formation in kraft recovery boilers. No method exists to measure black liquor Black liquor is a byproduct of the Kraft process, (also known as Kraft pulping or sulfate process) during the production of paper pulp. Wood is decomposed into cellulose fibers (from which paper is made), hemicellulose and lignin fragments. droplet droplet very small drop of fluid. droplet nuclei the finite particles of matter which are transmitted from animal to animal. size under in-furnace conditions, so we set out to devise a method to predict the droplet size from spray characteristics near the splashplate. Black liquor was sprayed through a splashplate nozzle into a spraying chamber at three mass flow rates and three spraying temperatures. We measured the drop size distribution at 4 m from the splashplate and observed different spray disintegration mechanisms, depending on the spraying parameters. We searched the dominating frequency of ligaments forming from the spray centerline cen·ter·line n. 1. A line that bisects something into equal parts. 2. A painted line running along the center of a road or highway that divides it into two sections for traffic moving in opposite directions, or, in the case of at the sheet break-up point to calculate the size of ligaments. The break-up point and the shape of the uniform black liquor sheet were determined using image-analysis-based algorithms developed in this study. The developed algorithm gives reasonable results, and can be used to scan the whole spray to determine the length of the sheet at desired intervals. The wavelength distribution near the sheet break-up point can be used to determine the completeness of the disintegration process. If the distribution is wide, it indicates an incomplete disintegration. Fast Fourier transform See FFT. (algorithm) Fast Fourier Transform - (FFT) An algorithm for computing the Fourier transform of a set of discrete data values. Given a finite set of data points, for example a periodic sampling taken from a real-world signal, the FFT expresses the data in terms of (FFT (Fast Fourier Transform) A class of algorithms used in digital signal processing that break down complex signals into elementary components. FFT - Fast Fourier Transform ) and autocorrelation Autocorrelation The correlation of a variable with itself over successive time intervals. Sometimes called serial correlation. functions were used to find the dominating wavelength of the sheet, but more than one wavelength may be significant. Several wavelengths exist simultaneously, resulting in various sizes of droplets. In the flashing case, the drop size similar to the results from the drop size measurements would be achieved by multiplying the diameter of the ligament by 1.3 (or 2.3 in the non-flashing case). Future work in this field focuses on the applicability of the drop size predictions to furnace conditions and further wave distribution analysis. View this paper online at http://www.tappi.org/index.asp?pid=32226&ch=1 Pasi Miikkulainen, Ari Kankkunen, Mika P. Jarvinen, and Carl-Johan Fogelholm are with Helsinki University of Technology TKK redirects here. For other uses, see TKK (disambiguation). Helsinki University of Technology is not to be confused with University of Helsinki. Helsinki University of Technology (TKK) (Finnish: Teknillinen korkeakoulu; Swedish: Tekniska högskolan , Laboratory of Energy Engineering and Environmental Protection, P.O. Box 4400, FIN-02015 HUT, Finland. Email Miikkulainen at pasi.miikkulainen@hut.fi. |
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