Bioreactor Design - Universitas Brawijayanuristianah.lecture.ub.ac.id/files/2014/09/PTB_Reactor-Design.pdf · . 1 Nur Istianah ... up-flowing and down-flowing steams. ... Assume air

Bioreactor Design

MATA KULIAH: PENGANTAR TEKNOLOGI BIOPROSES

Nur Istianah-THP-FTP-UB-2014


Bioreactor: device, usually a vessel, used to direct the activity of abiological catalyst to achieve a desired chemical transformation.

Product

Bioreactor

Recycle

Product

separation & purification

Nutrients tank

Waste

Input

Pre-filtration

Fermenter: type of bioreactor in which the biocatalyst is a living cell.


What is a bioreactor?

http://upload.wikimedia.org/wikipedia/commons/7/71/Bioreactor_principle_svgedit.png

1Nur Istianah-THP-FTP-UB-2014

Biomass concentration

Nutrient supply

Sterile conditions

Effective agitations

Heat removal

Shear conditions

Product removal

Product inhibition

Aeration

Microbial activities

Bioreactor Performance

2

1. Aerobic bioreactor: Need adequate mixing and aeration

2. Anaerobic bioreactor: no need agitation

3. Semiaerobic bioreactor: No mixing, but need aeration


20%

70%

10%

aerobic

anaerobic

semiaerobic

Groups of Bioreactor

3

-1. Stirred tank

•Baffles are usually used to reduce vortex. D=3m, 4 baffles. D>3m, 6-8 baffles

• Applications: free and immobilized enzyme reactions. High shear forces may damage cells

•Require high energy input. Cooling can be used to cover excess heat


(+) Low cost

4

- 2. Bubble column

Application: production of baker’syeast, beer, vinegar, and waste water treatmentMixing method: Gas sparging•Simple design•Good heat and mass transfer•Low energy inputGas-liquid mass transfer coefficients depend largely on bubble diameter and gas hold-up.


1< H/D < 6

- 3. Airlift reactor

There are two liquid steams: up-flowing and down-flowing steams.Liquid circulates in an airlift reactor as a result of density differencebetween riser and downcomer. Aplication: alcoholic fermentation


Steril

Large capacity

Low shear

High cost

Poor nutrient distribution

Foaming


6

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.


- 4. Packed-bed reactor

7

•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.• Application: aerobic wastewater treatment


- 5. Trickle-bed reactor

8

•When the packed beds are operated in upflowmode, the bed expands at high liquid flow rates due to upward motion of the particles. •Channelling and clogging of the bed are avoided.•Application: wastewater treatment and the production of vinegar.


- 6. Fluidized bed reactor


FEDBATCH

PLUG FLOW CSTR

http://commons.wikimedia.org

http://www.aspentech.com

http://commons.wikimedia.org

Bioreactor Operation Modes

BATCH

10

A batch bioreactor is normally equipped with an agitator to mix the reactant, and the pH of the reactant is maintained by employing either buffer solution or a pH controller

Sm

Ss

CK

Cr

dt

dCr

max

trCCC

CK ss

s

sm max0

0ln Change of Cs with time, t

Batch operation with stirring

•A foam breaker may be installed to disperse foam


-1.a. Batch Operation


-1.b. Fed Batch Operation

11

In a plug-flow reactor, the substrate enters one end of a cylindrical tube with is packed with immobilized enzyme and the product steam leaves at the other end.

max0

0ln rCCC

CK ss

s

s

m

F, Cs0 F, Cs

t = 0F

V

An ideal plug-flow reactor can approximate the long

tube, packed-bed and hollow fiber or multistaged reactor

Residence time

Continuous operation without stirring

V


-2. Plug-flow mode

12

A continuous stirred-tank reactor (CSTR) is an ideal reactor which is based on the assumption that the reactants are well mixed.

Continuous operation with

stirring

F, Cs0

F, Cs

V


-3. Continuous stirred-tank

dt

dXVVrXXF x )( 0

F, Cs0

F, Cs

V

Mass balance of cell:

onAccumulati GOutput -Input eneration


the ratio of biomass rate of generation to biomass concentration, rx/X, that is the specific growth rate; μ

)(

)( 0

XX

D

rXXV

Fx

X

rx

D

0dt

dX sSteady state:

DV

F

1

00 XNo cell in inlet:

-3. Continuous stirred-tank – cont.


Monod rate:SK

S

s max

SK

SD

s max

D

DKS s

max

At steady state, substrate utilisation is balanced with a rate equation:

VSK

SSSF

s

max

0 )(

SK

SSSD

s

max0 )(

SS

XXY

0

0

D

DKSYXX s

max

00


Bioreactor Design Properties

1 • Mass Transfer

2 • Heat Transfer

3 • Dimension

4 • Power consumption

5 • Hold Up


1 • Mass Transfer

Determine KLa

α is proportionality factor, 2x10-3


2 • Heat Transfer

The reaction in bioreactor, especially fermentation:

generate HEAT

Need cooling (coils or jacket in vessel)

Conduction

single layer

multi layer

Convection Natural

Forced

x

TkAq

x

ThAqx


3 • Dimension

1. Reactor volume

2. Reactor diameter

3. Ratio of reactor diameter to impeller diameter

Dt/Di

4. Ratio of the height of the liquid level to impeller

diameter, HL/Di


4 • Power consumption

Power consumption per unit volume of liquid

Power consumption:

53

i

c

pDN

PgN

c

ip

g

DNNP

53

NP is a function of Re and type of impeller Use graph

N = rpm/60 = ... rps



Correction factors are used to define actual power

Pact = P. Fc. number of impeller

There is a further discussion for aeration power(next subject)


5 • Hold Up

Assume air in water

kcalYCVq

1

Heat production rate:

q : heat production rate, kcal/ls

V: reactor liquid volume, l

: specific growth rate, s-1

C: biomass concentration (g/l)

Ykcal: a yield coefficient given as

grams of cells formed per kcal energy

released, g cells/kcal

Heat load: Heat load is determined by energy balances

Practical Issues for Bioreactors- Temperature Control (Heat Load)

Popular method


-Temperature control (heat transfer)

Heat transfer surface area: 1. Low in (a) external jacket and (b) external coil for small reactors

2. High in (c) internal helical coil and (d) internal baffle coil for large reactors

3. Easily adjustable in (e) a separate external heat exchange unit

Difficult to clean

Easily fouled by cell

growth on the

surface

No cleaning problem

• Sterility

requirement

• Shear forces

imposed on cells

• Depletion of

oxygen Nur Istianah-THP-FTP-UB-2014

1. Biological reactions almost invariably are three-phase reactions (gas-liquid-solid). Effective mass transfer between phases is often crucial. For example, for aerobic fermentation, the supply of

oxygen is critical.

HPCgAA

* gAAlA CCKJ *

The equation governing the oxygen transfer rate is:

Agitation:

•Mechanical stirring (for small reactors, and/or viscous liquids, low reaction heat)

•Air-driven agitation (for large reactors and/or high reaction heat)

-Agitation (gas transfer)


19

1. Mechanical foam breaker (a supplementary impeller)

2. Chemical antifoam agents (may reduce the rate of oxygen transfer)

- Foaming removal


20

1. Aseptic operation (3-5% of fermentations in an industrial plant are lost due to failure of sterilization.

2. Construction materials (glass for small bioreactors, e.g., < 30 liters and corrosion-resistant stainless steel for large reactors)

3. Sparage design (three designs: porous, orifice and nozzle)

4. Evaporation control due to dry air input

- Other issues


THANKS FOR YOUR ATTENTION

The best person is one give something useful always


Documents

Bioreactor Design - Universitas Brawijayanuristianah.lecture.ub.ac.id/files/2014/09/PTB_Reactor-Design.pdf · . 1 Nur Istianah ... up-flowing and down-flowing steams. ... Assume air