Abstract
Voids that are formed by gas injection in a packed bed play an important role in metallurgical and chemical furnaces. Herein, two-phase gas–solid flow in a two-dimensional packed bed during blast injection was simulated numerically. The results indicate that the void stability was dynamic, and the void shape and size fluctuated within a certain range. To determine the void morphology quantitatively, a probabilistic method was proposed. By statistically analyzing the white probability of each pixel in binary images at multiple times, the void boundaries that correspond to different probability ranges were obtained. The boundary that was most appropriate with the simulation result was selected and defined as the well-matched void boundary. Based on this method, the morphologies of voids that formed at different gas velocities were simulated and compared. The method can help us to express the morphological characteristics of the dynamically stable voids in a numerical simulation.
Highlights
Voids that are formed by gas injection in a packed bed are critical in various applications, such as moving-bed coal gasifiers [1], blast furnaces [2] and COREX melting gasifiers [3]
We propose a new approach to determine the void morphology based on a probabilistic method by analyzing each pixel in the obtained simulation images of the void
3a, after gas injection, a void with a plume-like shape
Summary
Voids that are formed by gas injection in a packed bed are critical in various applications, such as moving-bed coal gasifiers [1], blast furnaces [2] and COREX melting gasifiers [3]. The tuyere raceway in the lower part of the blast furnace is exactly the void that is formed by a high-pressure air blast, which provides heat and a reducing gas for reaction in the upper part. The void morphology (i.e., shape and size) is believed to be an important factor to determine the distribution of the reducing gases and heat [4]. An exploration of the void morphology has important implications for controlling the gas distribution and reactions [5]. X-ray computed tomography (CT) was used by Nogami et al [12]
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