OCR Text |
Show General Fuel Properties The parent coals used to make the slurries determine the basic fuel properties (proximate, ultimate, heating value, etc.) of the fuels. Slurry production processes including a coal cleaning step are an exception, of course, since cleaning can significantly alter the properties of the feed coal. Deposition The chemical additives can change the chemical composition of the ash enough to change the deposition characteristics of the coal. A negative effect was an increase in the fouling potential (relative to the parent coals) of the slurries in which a sodium-containing additive was used. The CWS vendors were notified and are taking steps to eliminate the sodium. Figure 6 shows the fouling potential of the parent coals and CWS fuels tested in this program plotted as a function of the sodium content of the ash. The curve represents B&W's standard correlation developed using hundreds of coals. It is clear that all of the fuels are in substantial agreement with the standard correlation. This provides justification for interpreting the fouling potential predictions for CWS in terms of their sodium content. Stability Stability tests simulating tank storage and truck, barge, and rail transportation indicated that all of the fuels were relatively stable for periods up to three weeks; however, it is recommended that transportation, storage, and handling systems contain provisions to prevent or reentrain settled material. No difference in settling was noted between tank storage conditions and simulated transportation conditions. -13- |