QUESTION ONEA simplified flow sheet for the manufacture of sugar is shown in Figure 2.7.Sugar cane (S1) is fed to a mill where a syrup is squeezed out, and the resulting gases (S2) contain 80% pulp. The syrup (S3) containing finely divided pieces of pulp is fed to a screen, which removes all of the pulp in a waste stream (S5) and produces a clear syrup (S4) containing 15% sugar and 85% water. The evaporator produces water (S6) and a heavy syrup (S7) containing 40% sugar.The crystallizer produces water (S8) and 1000 lb/h of pure sugar crystals (S9).The objective is to determine all unknown flow rates and compositions and to calculate a process efficiency as lb of sugar obtained per lb of sugar cane. Can you think of another meaningful definition of efficiency for the process?Define each unit as a processing system in order to expose all streams for analysis. Following is summary for all of the systems using mass fractions and total mass flow rates as the variables:

QUESTION TWOA condensed version of the process for the manufacture of formaldehyde is shown in Figure 2.9. Methanol is oxidized to formaldehyde using air as the source of oxygen. CH3OH +1/2O2 HCHO + H2OThe reactor is a fixed bed containing an iron–molybdenum oxide catalyst. The reactor feed, stream 4, contains 8 mol% methanol and 10 mol% oxygen. The methanol is completely converted in the reactor. A purge stream for nitrogen is taken off the overhead product from the separator. The purge contains no water. The bottom product from the separator is a 37 wt% solution of formaldehyde in water. The additional water required for this product is supplied to the separator in stream 5.Calculate the flow rates of the streams that have labels. Since we are not concerned with the unlabeled streams, we may group together the two splitters and the reactor together with the separator. Therefore, we can make mass balances on three equipment groups. Note that stream 3 and stream 7 have the same composition, but possibly different flows and that stream 7 is the only exit for nitrogen. Stream 4 therefore contains no water or formaldehyde.