β Scribed by Brian R. Stanmore; Stuart Budd
No coin nor oath required. For personal study only.
The condition which determines whether ash will cause fouling on heat transfer surfaces in p.c.-fired boilers is that the viscosity must lie between 0.1 and 10 MPa s. Ash under these conditions is stiff, exists in two phases and therefore exhibits a yield stress. A new type of rheometer consisting of a standard thermomechanical analyzer modified to act in the squeeze film mode is proposed to measure ash fluidity. Flat pellets of sample heated to operating temperature under a stream of nitrogen were subjected to a constant compressive load. Analysis of the sample thickness at any point and its rate of deformation provided the Bingham viscosity and yield stress. An ASTM glass at 750Β°C gave a viscosity near the standard value, while a brown coal fly ash exhibited a yield stress of ~1 kPa at 1190Β°C.
π SIMILAR VOLUMES
## Abstract A screw extruder and capillary dies of different length radius ratios were used to measure melt flow and end effects for three commercial polyethylene resins, two of low density and one of high density. The apparent melt viscosities of the low density resins decreased faster with increa