Generic closed control loop of a high efficiency low volume bioethanol distillery : a thesis presented in partial fulfilment of the requirements of the degree of Master of Engineering in Mechatronics at Massey University, Auckland, New Zealand
Bioethanol is a type of biofuel that is created by fermenting organic
materials into a solution called mash. This mash contains water, dead
yeast cells, feed stock solids, and 10% - 15% bioethanol (alcohol). The
bioethanol is extracted by heating the mash above the boiling point of
ethanol to create a vapour which is then condensed in to a liquid that is
greater than 93% bioethanol in a process called distillation.
bioethanol is a viable replacement for petrol, however comparisons
between the two fuel types show that with the current processes used
petrol has a higher net energy yield. Bioethanol contains 30% less energy
than petrol, so to compete with petrol bioethanol must be created in a
way that greatly reduces its total energy cost. The most energy intensive
process in the production of bioethanol is distillation, an Advanced
Process Control algorithm (APC) must be implemented to make this
process more efficient.
My project is based on the implementation of an APC to increase the
efficiency of a bioethanol still. By using a Siemens PLC (Programmable
Logic Controller), combined with their PID (Proportional, Integral, and
Differential) control algorithms I intend to monitor and control the
distillation of a mash containing 14% bioethanol.
With this approach I have been able to manufacture a low volume still
that can produce high quality bioethanol consistently. This approach
increased the total bioethanol yield by 10%, also producing a solution
that is consistently above 93% ethanol which can be fed straight into a
molecular sieve for dehydration, producing 100% bioethanol that can be
used as a biofuel.