A naturally occurring compound in citrus fruits, citric acid (C6H8O7) is an important compound in aerobic respiration. As a food additive, the compound is a preservative to prevent discoloration of...

A naturally occurring compound in citrus fruits, citric acid (C6H8O7) is an important compound in aerobic respiration. As a food additive, the compound is a preservative to prevent discoloration of foods. In industry, citric acid is manufactured continuously using a submerged culture of Asperigillus niger in a batch reactor operated at 30°C:

For this reaction, the respiratory quotient is 0.45. The yield of citric acid per mole of glucose consumed is 0.70. The cell mass is given as CH1.79N0.2O0.5. The heats of combustion for the compounds in the chemical reaction are given in The inlet flow rates of glucose and ammonia are 20 kg/hr and 0.4 kg/hr, respectively. The inlet flow rate of oxygen is 7.5 kg/hr. The fractional conversion of glucose is 0.91. Mechanical agitation of the broth adds 15 kW of power to the system. One-tenth of the water produced by the reaction is evaporated. Estimate the cooling requirements. (Adapted from Doran PM, Bioprocess Engineering Principles, 1995.)