Beer is made with the yeast Saccharomyces cerevisiae, which
produces ethanol from the sugar glucose. Dissolved ammonia is used as the
nitrogen source in an industrial production of ethanol by use of an isothermal
batch fermenter of 1400 L. You must design a cooling jacket for the fermenter
such that the temperature inside the vessel is maintained at 25 ◦C
In the reactor, 0.451 C mol of ethanol and 0.235 C mol of
biomass with elemental composition CH1.8O0.56N0.17 were produced per C mol of
glucose by use of XXXXXXXXXXmol of ammonia.
The heats of combustion of the biomass are calculated from
the “regularization method” to be 519 kJ/C mol, and the heats of combustion of
ethanol, glucose, and ammonia are 383, 468, and 684 kJ/C mol, respectively (see
Sandler, 4th ed. Chapter 15)
a. Sketch the operation of a continuous fermenter into which
ammonia, water, and glucose are fed in continuously at 25 ◦C and air is
fed at 25 ◦C to supply oxygen.
b. Compute the heat of reaction per C mol of glucose
consumed.
c. Compute the minimum rate of cooling water required for
using Vessel B (in Example 3.1, which has been outfitted with the necessary
piping to operate continuously) withcooling water available at 5 ◦C if
the residence time in the fermenter is 4 h and the glucose concentration in the
feed is 50 g glucose/L.
d. Calculate the required cooling water flow and exit
temperature from the jacket if the overall heat transfer coefficient is 309 W/m2
K.