Modelling and simulation of a Single Cyclone for Optimal Efficiency for a Batch-Type Fixed-Bed Down-Draft Gasifier using CFD

Abstract

Modelling and optimization have long been established as a means of achieving efficiency in energy systems also in sustaining the environment. In Nigeria, where environmental pollution have become a challenge, the problem of pollution and safety has become a global concern whereby sustainable power generation systems with zero greenhouse emission will serve as a better way of sustaining the environment. Simulation been a basic similitude tool to real life engineering design enable the engineers to understand the interactive flow process within an operating systems, postulating operation results, designing process systems or optimizing the operating system with optimum accuracy. This tool enables an engineer to establish the geometrical parameters for the actual design of the system. Cyclones, which are widely used as air pollution abatement equipment, are used in processing industries for removal of particulate matter (PM). A 1D2D centrifugal fan power driven cyclone is attached to a batch-type fixed-bed downdraft gasifier was modelled and simulated to determine the behaviour of the gasification products and the optimal efficiency of the cyclone. Applying mathematical modeling and CFD tools to understand the effect of the gas stream on the cyclone performance and a new optimized cyclone geometrical ratios based on the mathematical model was attained. Establishing the cyclone modelling was done by applying the heat content simulation tool (MATLAB-Software package) and using the response surface methodology (RSM) approach. The geometrical parameters in cyclone separators significantly affected the flow field and performance parameters. Analysis of the experimental design informed the researcher on the relationship between the effects of inlet dimensions and the vortex finder diameter on the performance of the cyclone. The cyclone design and simulation of the cyclone has shown that it can effectively remove solid particles from a gas stream (syn-gas). The calculation shows that collection efficiency for particle size of 13.18 μ m is obtained for the cyclone separator assuming all the particles leaving the cyclone is at that size. The designed simulated cyclone show that the new design when compared with the Stairmand design have a better performance over the later.