Kinematics and dynamics of suspended gasifying particle

Abstract

The effect of gasification on the dynamics and kinematics of immersed spherical and non-spherical solid particles have been investigated using the three-dimensional lattice Boltzmann method. The gasification was performed by applying mass injection on particle surface for three cases: flow passing by a fixed sphere, rotating ellipsoid in simple shear flow, and a settling single sphere in a rectangular domain. In addition, we have compared the accuracy of employing two different fluid-solid interaction methods for the particle boundary. The validity of the gasification model was studied by comparing computed the mass flux from the simulation and the calculated value on the surface of the particle. The result was used to select a suitable boundary method in the simulations combined with gasification. Moreover, the reduction effect of the ejected mass flux on the drag coefficient of the fixed sphere have been validated against previous studies. In the case of rotating ellipsoid in simple shear flow with mass injection, a decrease on the rate of rotation was observed. The terminal (maximum) velocity of the settling sphere was increased by increasing the ratio of radial flux from the particle boundary. IntroductionSolid particle gasification is part of many industrial processes such as combustion of carbonaceous solid fuels in a reactor or gasification of gas hydrate particles in an air lift pump [1,2]. Optimizing these processes to decrease the cost and environmental impacts requires having a profound insight about gasifying suspension behavior in flow.The size and shape of particles are within physical properties of the solid fuels, which strongly affect observed phenomena in combustors and gasifiers. For instance, the rate of gas-solid reactions depends on both available surface area and particle size [3]. Therefore, the study of each individual gasifying particle with different size and shape helps to understand certain properties of the particle flow in large scale.The motion of spherical and non-spherical particles has already been studied in different flow cases such as the settling of single spheres under gravity [4][5][6][7][8] and the rotation of an ellipsoid in simple shear flow [9][10][11][12][13][14]. The influence of mass injection from the surface of the solid particle has also been studied by previous authors [15][16][17] by implementing outflow on the boundary of a fixed sphere. In later works it is shown that there is a reduction in the total drag coefficient by injecting radial flux from the surface of the sphere which is correlate with mass injection ratios. However, to the best of our knowledge, the effect of mass injection on non-spherical or suspended solid particle behavior has so far remained untouched.There are several methods that have been applied to simulate suspension particles, e.g., the finite element method [18,19] or the immersed boundary method, in original form or in combination with other methods Z. Moradi Nour (B) · G. Amberg · M. Do Quang