Problem-

Grains, such as com and sorghum are used to produce ethanol for use in motor oil. A process for producing ethanol from grains is shown in the following figure. Crushed grains, water and enzymes are added to the enzyme reactor and heated to approximately 140°F and held at this temperature for 60-80 hours so that the enzymes can break down the carbohydrates of the grain into glucose. Steam is fed to a set of submerged coils in the tank to heat the solution and maintain the temperature. After the conversion to glucose is complete, the content of the enzyme reactor is pumped into the fermenter. Initially, a portion of the glucose stream is pumped into the fermenter and the inoculum (active yeast) is added. After the incubation period of approximately 2-3 hours, the reminder of the glucose from the enzyme reactor is pumped into the fermenter. Then the fermenter is operated at batch mode while maintaining pH by adding NaOH solution and temperature by using cooling water for total fermentation time of 15-20 hours until the desired EtOH concentration is attained. After the fermentation reactions are complete, the content is pumped to a distillation column, which concentrates EtOH in the overhead product to an 80 volume percent product. Please draw the control scheme with the following process information. The reflux ratio is 5. And, a partial condenser is used. The bottoms product of the column contains unconverted solids and weak EtOH solution (Figure given below).

(1) What is the control objective of this process?

(2) What safety control do you think are need for this process (do not need draw the scheme of safety controls)?

(3) Please draw the control scheme.

Additional information-

The problem relates to Mechanical Engineering and the problem is about the process of producing ethanol for motor oil production. The whole schemas for ethanol production starting from grain to glucose conversion, fermentation process and distillation process have been given. The safety control and safety schema of the process needs to be improved and verified. The solution contains all the details.