Measurement of flyash and bottom ash flow rates from a circulating fluidized bed boiler

The measurement of the flow rates of flyash and bottom ash from a Circulating Fluidized Bed (CFB) boiler has a number of uses. Among these are the requirements of boiler performance testing, the development of particle population models for assessing key chemical interactions taking place in the combustion chamber, and the partitioning of key species between flyash and bottom ash. Identification of partitioning of key species between flyash and bottom ash (combustibles, calcium, sulfur) can lead to improvements in key parameters of boiler operation. Current methods for the computing of the flow rates of these ash streams include 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 intensive and as such, not routinely feasible. Offered here is a method for computing the flow rates of ash streams through 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 method permits the calculation of the ash stream flow rates without the direct measurement of either, and can be practiced on a routine basis.