Packed bed reactor

This presentation gives all the required information about pack bed bioreactor, including, advantages, disadvantages, applications and even how to overcome the disadvantages. Packed bed bioreactor is the major type of bioreactor used in waste water treatment as it involves the usage of catalyst. There are different types of packed bed bioreactors and they are used according to the desired product. There is picture representation and also tabular form of differentiation.
I have also mentioned the references at the end.

1. PACKED BED REACTOR MADE BY : SNEHAL SALUNKHE D.Y. PATIL DEEMED TO BE UNIVERSITY, SCHOOL OF BIOTECHNOLOGY AND BIOINFORMATICS, NAVI MUMBAI Course: B.Tech Biotechnology Year: 3 rd (6 th semester) Session: 2018-2019

2. INTRODUCTION In chemical processing, a packed bed is a hollow tube, pipe, or other vessel that is filled with a packing material. The packing can be randomly filled with small objects like  Raschig rings  or else it can be a specifically designed structured packing. Packed beds may also contain catalyst particles or adsorbents such as zeolite pellets, granular activated carbon , etc. Fig. 1 Packed bed reactor

3. The purpose of a packed bed is typically to improve contact between two phases in a chemical or similar process. Packed beds can be used in a  chemical reactor, a distillation process, or a scrubber , but packed beds have also been used to store heat in chemical plants. The packed bed reactors are widely used with immobilized cells.

4. STRUCTURE/ CONSTRUCTION

5. ADVANTAGES By using a packed bed reactor is the higher conversion per weight of catalyst than other catalytic reactor.  The reaction rate is based on the amount of the solid catalyst rather than the volume of the reactor.  Low operating cost and low maintenance by using this kind of reactor.  The process using packed bed reactor operates continuously.  Little wear on catalyst and equipment.  Simple analysis  Little loss or attrition.  Only practical, economic reactor at very high pressures.  Usually high ratio of catalyst to reactants long residence time complete reaction

6. CHALLENGES/ LIMITATIONS   For the first aspect which is TEMPERATURE CONTOL  and the challenge that have to face in are: ENDOTHERMIC REACTIONS MAY DIE OUT EXOTHERMIC REACTION MAY DAMAGE THE REACTOR SELECTIVELY CONTROL

7. SINGLE BED REACTOR MULTI-BED REACTOR MULTI-TUBE REACTOR

8. SINGLE BED REACTOR MULTI-BED REACTOR MULTI-TUBE REACTOR

9. For the second aspect which is PRESSURE DROP:  Friction between the gas and particle phase result in a pressure drop.  High pressure drop will result to high compression cost.  Some systems have low tolerance for pressure drop.  The pressure drop is mainly dependent on reactor length, particle diameter, void fraction and gas velocity.

10. The third aspect of limitation is CATALYST DEACTIVATION:   The catalyst gets deactivated if the active sites get contaminated.   Sulphur compound deactivate Ni-catalyst - Desulfurization is often necessary prior to reforming.   Formation of carbon deposit deactivate the catalyst - Large carbon deposits may clog the tubes, causing hot-spots that damage the reactor.   Catalyst regeneration is necessary.

11. DISADVANTAGES     Large temperature gradient or undesired thermal gradient may occur.  Inefficient heat exchange  Suitable for slow-or-non-deactivating processes.  Poor temperature control.  Channeling may occur.  Unit may be difficult to service and clean.  Swelling of the catalyst, deformation of the reactor.  Regeneration or replacement of the catalyst is difficult- shut down is required.  Pore diffusional problems intrude in large pellets

12. OVERCOMING THE DISADVANTAGES Monolithic supports will overcome the problems of non-uniform flow patterns, plugging high pressure for small pellets and pore diffusional problems. Temperature control problems are overcome with:  Recycle.  Internal and external heat exchanges.  Staged reactors  Cold shot cooling  Multiple tray reactor- fluid redistributed and cooled between stages and catalyst is easily removed which varied from tray to tray.  Use of diluents.  Temperature self-regulation with competing reactions, one endo and one exothermic.  Temperature control by selectivity and temporarily poisoning the catalyst

13. APPLICATIONS Synthesis of gas production  Methanol synthesis  Ammonia synthesis  Fischer- Tropsch  synthesis  valorization of food Gas cleaning (adsorption) Waste treatment Nutraceutical synthesis Packed column bed distillation is used to enhance contact between vapor and liquid instead of trays packing

14. PACKED BED BIOREACTOR FOR THE ISOLATION AND EXPANSION OF PLACENTAL-DERIVED MESENCHYMAL STROMAL CELLS ABSTRACT Large numbers of Mesenchymal stem/ stromal cells (MSCs) are required for clinical relevant doses to treat a number of diseases. To economically manufacture these MSCs, an automated bioreactor system will be required. Herein we describe the development of a scalable closed-system, packed bed bioreactor suitable for large-scale MSCs expansion. The packed bed was formed from fused polystyrene pellets that were air plasma treated to endow them with a surface chemistry similar to traditional tissue culture plastic. The packed bed was encased within a gas permeable shell to decouple the medium nutrient supply and gas exchange. This enabled a significant reduction in medium flow rates, thus reducing shear and even facilitating single pass medium exchange. The system was optimised in a small-scale bioreactor format (160 cm2) with murine -derived green fluorescent protein-expressing MSCs, and then scaled-up to a 2800 cm2 format. We demonstrated that placental derived MSCs could be isolated directly within the bioreactor and subsequently expanded. Our results demonstrate that the closed system large-scale packed bed bioreactor is an effective and scalable tool for large-scale isolation and expansion of MSCs.

15. GFP- mMSC expansion in a scaled-up packed bed bioreactor (A) The fold expansion of GFP- mMSC in a scaled-up bioreactor under 0.5 ml/min perfusion with T175 flask control (n = 4). (B) Glucose and lactate levels in the bioreactor (n = 3). (C, D, E & F) IVIS imaging of the fluorescent intensity of PI stained GFP- mMSC in the bioreactor.

16. REFERENCES www.wikipedia.org https://www.scribd.com/document/223520329/Packed-Bed-Reactor https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0144941 www.google.com