The measurement of flyash and bottom ash plow rates from a circulating fluidized bed boiler

The measurement of the flow rates of fly ash and bottom ash from a Circulat ing Fluidized Bed (CFB) boiler has a number of uses. Among these are the re quirements of boiler performance testing, the development of particle popul ation models for assessing: key chemical interactions taking place in the c ombustion chamber, and the partitioning of key species between fly ash and bottom ash. Identification of partitioning of key species between fly ash a nd bottom ash (combustibles, calcium, sulfur) can lead to improvements in k ey parameters of boiler operation. Current methods for the computing of the flow rates of these ash streams in clude the measurement of the flow rates of feed solids, one ash stream flow rate, and inference of the other from a material balance. This is effort i ntensive and as such, not routinely feasible. Offered here is a method for computing the flow rates of ash streams throug h measurement of the solids feed rates to the system, and solving material balances around inorganic solids (total ash) calcium and/ or sulfur, using these material balances as a simple set of simultaneous equations. This met hod permits the calculation of the ash streamflow rates without the direct measurement of either, and can be practiced on a routine basis.