DIFFERENT CONFIGURATIONS OF BIOREACTOR
- 1. Different configurations of bioreactor Seminar by, Urmila .N.Pai 6th sem SCET
- 2. - 1. Stirred tank
- 3. The continuous stirred-tank reactor, also known as vat- or backmix reactor, is a common ideal reactor type in chemical engineering. A CSTR oftenrefers to a model used to estimate the key unit operation variables when using a continuous agitated-tank reactor to reach a specified output.
- 4. Mixing method: Mechanical agitation •Baffles are usually used to reduce vortexing • Applications: free and immobilized enzyme reactions •High shear forces may damage cells •Require high energy input
- 5. - 2. Bubble column
- 6. • Mixing method: Gas sparging • Simple design • Good heat and mass transfer • Low energy input • Gas-liquid mass transfer coefficients depend largely on bubble diameter and gas hold-up.
- 8. - 3. Airlift reactor
- 9. Air-lift bioreactors are similar to bubble column reactors, but differ by the fact that they contain a draft tube. The draft tube is always an inner tube (this kind of air-lift bioreactor is called "air-lift bioreactor with an internal loop) or an external tube (this kind of air-lift bioreactor is called "air-lift bioreactor with an external loop) which improves circulation and oxygen transfer and equalizes shear forces in the reactor
- 10. • Mixing method: airlift • Compared to bubble column reactors, in an airlift reactors, there are two liquid steams: up-flowing and down-flowing steams. Liquid circulates in an airlift reactor as a result of density difference between riser and downcomer.
- 12. • Packed-bed reactors are used with immobilized or particulate biocatalysts. • Medium can be fed either at the top or bottom and forms a continuous liquid phase.
- 13. • In packed bed reactors, cells are immobilized on large particles. These particles do not move with the liquid. Packed bed reactors are simple to construct and operate but can suffer from blockages and from poor oxygen transfer. • Continuous packed bed reactors are the most widely used reactors for immobilized enzymes and immobilized microbial cells. In these systems, it is necessary to consider the pressure drop across the packed bed or column, and the effect of the column dimensions on the reaction rate.
- 14. • There are three substrate flow possibilities in a packed bed and they are illustrated below: • 1. Downward flow method • 2. Upward flow method • 3. Recycling method • The recycling method is advantageous when the linear velocity of the substrate solution affects the reaction flow rate. This is because the recycling method allows the substrate solution to be passed through the column at a desired velocity.
- 15. • For industrial applications, upward flow is generally preferred over downward flow because it does not compress the beds in enzyme columns as downward flow does. When gas is produced during an enzyme reaction, upward flow is preferred. • A continuous packed bed reactor has the following advantages over a batch packed bed reactor: • 1. Easy, automatic control and operation • 2. Reduction of labor costs • 3. Stabilization of operating conditions • 4. Easy quality control of products
- 17. • The trickle-bed reactor is another variation of the packed bed reactors. • Liquid is sprayed onto the top of the packing and trickles down through the bed in small rivulets.
- 18. A trickle-bed reactor (TBR) is a chemical reactor that uses the downward movement of a liquid and gas over a packed bed of catalyst particles. It is considered to be the simplest reactor type for performing catalytic reactions where a gas and liquid (normally both reagents) are present in the reactor and accordingly it is extensively used in processing plants. Typical examples are liquid phase hydrogenation in refineries (three phase hydrotreater) and oxidation of harmful chemical compounds in wastewater streams.
- 19. - 6. Fluidized bed reactor
- 20. • When the packed beds are operated in upflow mode, the bed expands at high liquid flow rates due to upward motion of the particles.
- 21. Fluidized bed reactor (FBR) is a type of reactor device that can be used to carry out a variety of multiphase chemical reactions. In this type of reactor, a fluid (gas or liquid) is passed through a granular solid material (usually a catalyst possibly shaped as tiny spheres) at high enough velocities to suspend the solid and cause it to behave as though it were a fluid. This process, known as fluidization, imparts many important advantages to the FBR. As a result, the fluidized bed reactor is now used in many industrial applications.