Computational investigation of hydrodynamics and drying of industrial sludge waste in a spouted bed column

Department of Chemical Engineering, National Institute of Technology Karnataka, Surathkal-575 025, Karnataka, India
E-mail: ashrafmchem@gmail.com
Manuscript received online 21 March 2020, accepted 12 June 2020

The disposal of sludge from waste water treatment plants adversely affects the environment. Since sludge wastes are sticky, drying of such waste water sludge is challenging. Conventionally, these sludges are dried in open spaces where a large area of land is required which is a time-consuming process. To overcome this, spouted bed is used in the present investigation. The spouted bed is a gas-solid contactor for handling coarse particles of size greater than 1 mm with low operating pressure. In this work,  ydrodynamics of waste water sludge in a conventional spouted bed is numerically investigated using Computational Fluid Dynamics (CFD). Euler-Eulerian CFD model is used to study the flow pattern in such system. The continuous phase turbulence (air) is modeled using standard Ƙ - ε model. The spouting height and solid circulation rate are calculated to analyze spouting behavior. This is compared with a draft tube spouted bed system and found that the draft tube supports in enhancing the spouting characteristics of the bed. Further, an optimum draft tube configuration is found that promotes solid circulation rate. The drying characteristics are analyzed for various operating conditions and found that the temperature of air significantly improves the rate of drying.