Study of gasification of coal

• Main Author: Ng, Jing Xian.
• Other Authors: Zhao Yong
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Mechanical engineering
• Online Access: http://hdl.handle.net/10356/16238
• Institution: Nanyang Technological University

Coals have been used widely in the world as an energy source by burning it. However, the products produced by burning of coal is damaging to the environment. Therefore, other methods of extracting energy from coal are invented. One of them is the gasification of coal. Gasification of coal is a process that converts coal into carbon monoxide, methane and hydrogen gas. It is made up of four processes which are drying, pyrolysis, combustion and gasification process. The gas mixture produced is called synthesis gas or syngas and is itself a fuel. Gasification of coal is a very efficient method for extracting energy from coal, and its products are non hazardous or damaging to the environment. There are three different types of gasification of coal processes which are the entrained bed flow, fluidized bed flow and moving bed flow. The type of gasification of coal process used in this report is the fluidized bed flow. In this report, a computational study of the gasification of coal was done with the help of a commercial Computational Fluid Dynamics (CFD) software, FLUENT. The vessel used in the report is first drawn and meshed in GAMBIT, and then the meshed vessel is imported to FLUENT for simulation. Standard k-ε turbulence model together with P-1 radiation model and non-premixed combustion model were used to stimulate the gasification process. Mesh independence study was done to ensure that the mesh interval size used in the report is valid. The simulation only considered the gasification and combustion process of the gasification of coal. The volatile products obtained from the pyrolysis and drying process are calculated using chemical equations. The result obtained from the simulation shows that the optimal temperature for producing the maximum amount of hydrogen gas is 795k and the optimal pressure is atmospheric pressure. The results obtained from this report are similar with the equilibrium data from the book Gasification Technologies written by John, and Nicholas [3], but due to the lack of the pyrolysis and drying process, the temperature range obtained from the report was slightly lower.