1. Instrumentation and Control
Abira Khan

2. Sensors
3 main classes:
Sensors which penetrate into the interior of the fermenter, e.g. pH electrodes, dissolved-oxygen electrodes.
Sensors which operate on samples which are continuously withdrawn from the fermenter, e.g. exhaust-gas analysers.
Sensors which do not come into contact with the fermentation broth or gases, e.g. tachometers, load cells
In relation to its application for process control:
In-line sensor
On-line sensor
Off-line sensor

4. Temperature Control Mercury-in-glass thermometers
Electrical resistance thermometers
Thermistors

5. Process Controls Flow measurement and control- Gases, Liquids
Pressure measurement and control
Safety valves
Agitator shaft power
Rate of stirring
Foam sensing and control
Weight- Load cell
Microbial biomass
Dissolved oxygen and carbon diooxide: P(O2)= C(O2)×PT
Inlet and exit-gas analysis
pH measurement and control
Redox potential

6. Thermal Mass Flowmeter

7. Foam Sensing and Control Unit

8. On-line Analysis of Other Chemical Factors
Ion-specific sensors
Enzyme and microbial electrodes
Near infra-red spectroscopy
Mass spectrometers

9. Control Systems A control loop consists of 4 basic components:
A measuring element
A controller.
A final control element
The process to be controlled
Manual control
Automatic control:
Two-position controllers (ON/OFF).
Proportional controllers.
Integral controllers.
Derivative controllers

10. Simple Manual/Automatic Control Loop for Temperature Control

11. Control Systems Combinations of methods of control
Proportional plus integral
Proportional plus derivative
Proportional plus integral plus derivative

12. Aeration and Agitation

13. O2 Transfer from Gas to Liquid Phase
KLa, the volumetric mass-transfer coefficient, the units of which are reciprocal time (h -1)
The volumetric mass-transfer coefficient is used as a measure of the aeration capacity of a fermenter
The larger the KLa, the higher the aeration capacity of the system
The KLa value will depend upon the design and operating conditions of the fermenter and will be affected by such variables as aeration rate, agitation rate and impeller design

14. Reference
Principles of Fermentation Technology- Stanbury- 2nd edition, Chapter 8, 9