Injectant Coal Gasification, Char Formation and Char Utilisation at High Injection Rates
Author | : European Communities |
Publisher | : |
Total Pages | : |
Release | : 2004 |
Genre | : |
ISBN | : |
The aim of this project was to carry out an integrated laboratory, pilot and plant scale investigation of injectant coal gasification, char formation and properties, the effect of char on melting zone behaviour and the utilisation of char in terms of top gas dust carryover at high levels of injection. Laboratory-scale studies undertaken by Corus and Imperial College of Science, Technology and Medecine (ICSTM), focused on the degree of burnout of injectant coals, morphology and reactivity of resultant chars and an evaluation of the potential for the formation of soot precursors. Extents of gasification were related to parent coal properties and correlations between char morphology and parent coal VM content were established. The experiments also determined rates of particle mass loss under the variety of conditions that exist within the coal injection plume and made a significant contribution to the understanding of how and where volatiles are released and whether chars will be completely gasified. Centra Sviluppo Materiali (CSM) concentrated on the influence of char particles on the rheological properties of the ferrous materials in the blast furnace burden. Laboratory-scale tests under simulated blast furnace conditions on mixtures of ferrous burden, coke and char were conducted in the SMEDRA (Softening MElting DRipping Apparatus). The presence of char in the ferrous materials caused changes to the extent of initial dripping and to the starting temperature of this phenomenon. These changes correlated to the amount of char added and to the characteristics of the parent coal (the VM content and whether pulverised or granular grade) and would affect the position and the shape of the melting zone in the blast furnace. At the plant scale , ThyssenKrupp Stahl sampled blast furnaces operating with coal injection and characterised the dust collected. Tests were carried out based on the knowledge that increased graphitisation of carbon occurs with rising temperature, allowing the source of the carbon to be identified. With a new analytical method, Microwave-Assisted Dissolution, it was possible to exactly quantify the smallest quantities of graphite in top gas dust. The amount of dust discharged through the furnace top was largely determined by the percentage of non-carbonaceous components, but a clear correlation between the quantity of discharged dust and the quantity of carbonaceous components was also found. The findings also indicated that the carbon in the dust from the centre of the furnace comes mainly from ungasified injectant coal char.