Rheological and atomization characteristics of coal-water mixture fuel

Abstract

The CWM (Coal-Water Mixture) fuel that comes to the front recently as one of important coal utilization technologies enables coal to be burned in a liquid-state to settle a lot of inconveniences and disadvantages that coal has as a solid-state fuel. It is assessed as a technology by which high economics and short-term commercialization might be realized in comparison with the gasification or liquefaction technologies of coal. In order to enhance CWM combustion efficiency and to prevent sedimentation phenomenon during long-term storage, it is essential to prepare CWM with high concentration and stability but low viscosity. Hence, it becomes a very significant step in CWM preparation, storage, transportation, and atomization technology to investigate the rheological behavior of CWM fuel. This study was carried out mainly for the following two purposes: One is to find out various factors affecting the rheological properties of CWM, togetherwith their correlations, in order to develop highly-loaded CWM with low viscosity and high stability, considering the preparation, transportation, and atomization aspects of CWM. The other is to investigate the discharge and atomization characteristics of CWM fuel, using one-nozzle internal-mixing atomizer, as a primary stage to secure the design data for atomizer by which fine CWM droplets can be produced. Study for the Rheological Behavior of CWM In order to investigate the rheological behaviors of CWM principal to the preparation, transportation, atomization and combustion technologies of CWM fuel, the influence of various parameters such as coal properties, coal loading, type and amount of additive, temperature, and size and its distribution of coal particles was studied on the apparent viscosity and non-Newtonian behaviors of CWM. Additionally, CWM viscosity, yield stress, and non-Newtonian behavior in the binary and ternary mixture composed of the coal particles with different mean size were investigated for 30 coal ...