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Show - Functions as a spare pulverizer during periods of pulverizer maintenance. - Restores a portion of lost load on existing units resulting from a deterioration in coal quality. While DIPC was developed to fill a growing need related to utility boilers, much of the technology is applicable to other process applications. The technological developments related to the storage, feeding and dense phase transport of pulverized coal are of particular value to those interested in conversion of existing industrial boilers and process heaters from gas or oil to pulverized coal. Prior to this program, only dense phase solids transport involving saltating or slug flow was well known. Such solid fuel transport was acceptable for many applications, but not for fuel supply to the burner, because of the inherent non-uniformity of the flow. In saltating or slug flow the bulk solid is transported in waves or slugs down the pipe line. As solids are introduced into the pipe line, the transport media entrains the solids and moves them down the pipe for only a short distance before some of the solids begin to drop out and form low density drifts. As this occurs, the velocity of the transport media increases in the area above the drift until a point is reached where reentrainment begins. As more material is reentrained the effective density of the entraining media increases, thus suspending the remainder of the drift at a higher rate until the entire drift is reentrained. Once this occurs, the fall out of particles begins again and the drift reforms some distance down stream. This drop out process, followed by reentrainment, is known as saltation and repeats itself over and over down the pipe. Hence in true dense phase the solids flow is not uniform but pulses violently resulting in slugs of fuel being transported with time. Figure 1 shows the drifting action described above and Figure 2 shows a typical variation in fuel rate with time that can be expected if true dense phase transport were employed. 11-4 |