Vineet Kumar

Computational modeling using the high-viscosity laminar flow approach was applied to study the effect of slab crossing time on slab heating and scale growth. Simulation of an existing industrial walking beam reheating furnace with four zones, outer refractory body, skid, slab, and fluid zone is considered. The fuel used was a mixture of coke oven and blast furnace gas. Preheated air is supplied co-axially with the fuel mixture. The combustion simulation is performed using the constrained equilibrium mixture fraction model. From the results, it has been observed that with an increase in slab residence time, the slab temperature and scale growth increase across the slab. For the system considered, with a fuel mass flowrate of 70,000 kg/h, 150–180 min of slab crossing time is appropriate to obtain desired slab temperature at the discharge end. The overall equivalence ratio is taken as Φ = 1 (fuel/air ratio is the same as stoichiometric ratio). The maximum slab scale thickness is evaluated as 2.4 mm at the discharged end for 180 min of slab crossing time.

Separation of pollutants from wastewater is a vital process. Several widely different designs known as modules, using membranes of various shapes, sizes, and support, have been used in the last decades. Many researchers have shown the great importance of membrane-based separation processes such as nanofiltration, reverse osmosis, ultrafiltration, which are widely used in wastewater treatment plants. The study of membrane performance in a wastewater plant is an expensive affair as it requires a pilot plant system to predict the outcome. A design engineer needs a more detailed understanding of the process (using reliable and accurate analytical tools). However, due to the microscopic nature of the membrane separation processes, it becomes very difficult to practically observe all the activities near the membrane surface (or inside a micro-tube) in greater detail. To overcome this, one must rely upon mathematical tools to simulate possible microscopic behavior and predict the macroscopic outcome of a membrane module that can be compared to validate the model. In this chapter, we have discussed the computational fluid dynamics approach combined with the mass transfer model, which predicts the behavior of the membrane module system.

The present work is aimed at unsteady-state mathematical modeling and simulation of the steam gasification of a single char particle. The unsteady state diffusion-reaction competitive gasification of a porous non-catalytic solid (char) was solved numerically using the staggered grid finite volume method (SGFVM). It was assumed that the char particle is spherical in shape and there is no change in its size during the gasification, and temperature variation within the particle is negligible. The model is capable of predicting detailed point-to-point reaction, diffusion, and concentration profile in a spatiotemporal domain inside the particle. The study revealed that the gasification of the char particle at higher temperature (>1,100 K) bear a resemblance to the shrinking core model and at a lower temperature (<1,100 K) it follows the progressive conversion model. The study also includes the effects of the temperature, time, and carbon concentration on the rate and conversion inside the char particle.