The Boiler blowdown rate depends on the quantity of the impurities and the limits of tolerance for the employees. The Blowdown rate is a product of the steam consumption and the ratio of the level of the TDS to the difference between the maximum allowable TDS and the actual TDS.

**q**

_{BD}^{ }= q_{S }f_{c}/ (b_{c}- f_{c})where

q

_{BD }the blowdown rate in kg/hourq

_{S}is the rate of steam consumption in kg/hourf

_{c}is the total dissolved substances in ppmb

_{c}is the limit of the total dissolved substances in ppm