Coal is conveyed into and combusted in a furnace for a power plant at the rate of 1 ton per minute. Air is also injected into the furnace. In the combustion process, two output streams are produced: (1) gas, which is directed to a stack for eventual discharge to the atmosphere, and (2) non-combusted solid residuals, or ash, which are removed at the bottom of the furnace. The coal contains a small amount of bromide, and after combustion this bromide is in the ash and the gas. To meet air discharge requirements for sulfur and prevent acid rain, a treatment system is installed that removes sulfur from the gas stream prior to discharging the gas stream to the stack. The sulfur removal unit incidentally removes ALL the bromide from the gas stream. Eventually, the removed sulfur and bromide are discharged to the nearby river. While the sulfur has a small effect on the river, the bromide is the focus of intense concern as bromide released into surface waters results in finished drinking water delivered to consumers that is high in carcinogenic disinfection by-products. The coal contains 0.001% bromide by weight. The ash contains 0.003% bromide by weight. The input air contains zero bromide. The combustion process produces 80 lb/min of ash. You are to determine how much bromide is removed from the gas stream as this amount of bromide will be released into the river.
a. Draw a mass balance diagram to assist with analysis of this problem.
b. Determine the rate of removal of bromide in the effluent gas treatment system. Your answer MUST be in pounds per day (lb/day).