Reactors

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Welcome Himanshu Kashudhan h imanshu.gbu@gmail.com

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Reactors

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What Is Rector R eactor 1 . Chemistry- Chem a substance, such as a reagent, that undergoes a reaction 2. (Physics / Nuclear Physics) short for nuclear reactor 3. (Chemistry) a vessel, esp one in industrial use, in which a chemical reaction takes place 4. (Electronics) a coil of low resistance and high inductance that introduces reactance into a circuit 5. (Medicine) Med a person sensitive to a particular drug or agent

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Type Of Rector Bioreactor , any device or system that supports a biologically active environment. Chemical reactor , a device for containing and controlling a chemical reaction. Nuclear reactor , a device for containing and controlling a nuclear reaction. Fusion reactor , a device for containing and controlling a fusion power reaction. L ine reactor is used to limit starting current of motors and to protect variable frequency drives.

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Bioreactor

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Bioreactor: device, usually a vessel, used to direct the activity of a biological catalyst to achieve a desired chemical transformation. Fermenter: type of bioreactor in which the biocatalyst is a living cell. What is a bioreactor?

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Aerobic bioreactor: Need adequate mixing and aeration Anaerobic bioreactor: no need for sparging or agitation Challenges in Bioreactor Design

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Bioreactor Configurations - 1. Stirred tank 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

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Bioreactor Configurations - 2. Bubble column 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.

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Bioreactor Configurations - 3. Airlift reactor 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 resutl of density difference between riser and downcomer.

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Bioreactor Configurations - 4. Packed-bed reactor 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.

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Bioreactor Configurations - 5. Trickle-bed reactor 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.

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Bioreactor Configurations - 6. Fluidized bed reactor When the packed beds are operated in upflow mode, the bed expands at high liquid flow rates due to upward motion of the particles.

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Bioreactor Operation Modes -1. Batch Operation 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 Change of Cs with time, t Batch operation with stirring A foam breaker may be installed to disperse foam

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Bioreactor Operation Modes -2. Plug-flow mode 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. F, Cs0 F, Cs t = 0 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

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Bioreactor Operation Modes -3. Continuous stirred-tank 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

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Bioreactor Operation Modes -3. Continuous stirred-tank reactor-Con. F, Cs0 F, Cs V Mass balance of substrate: Steady state: Michaelis-Menten rate:

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Bioreactor Operation Modes -3. Continuous stirred-tank reactor-Con. F, Cs0 F, Cs V Mass balance of substrate:

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Chemical Reactor

Types:

Types Fixed bed reactors Fluidized bed reactors Stirred tank reactors Slurry loop reactors Bubble columns

Fixed Bed Reactors:

Chemical Reactors and their Applications Fixed Bed Reactors Concept Collection of fixed solid particles. The particles may serve as a catalyst or an adsorbent. Continuous gas flow (Trickling liquid) Applications Synthesis gas production Methanol synthesis Ammonia synthesis Fischer-Tropsch synthesis Gas cleaning (adsorption)

Fluidized Bed Reactors:

Chemical Reactors and their Applications Fluidized Bed Reactors Concept Collection of solid particles dispersed in a continuous phase. The particles may serve as a catalyst, adsorbent or a heat carrier. Continuous flow of gas or liquid Applications Catalytic cracking processes Fischer-Tropsch synthesis Polymerization Waste combustion Drying

Stirred tank Reactors:

Chemical Reactors and their Applications Stirred tank Reactors Concept Forced mixing by use of impeller. Applied in reactive systems when mixing is the rate determining step. Single phase: liquid mixing. Two phases: liquid/gas, liquid/particle Three phases: liquid/particle/gas Typical applications Chemical component and phase mixing Fermentation reactor Food and paper industry Natural gas conversion/polymerization

Slurry loop Reactors:

Chemical Reactors and their Applications Slurry loop Reactors Concept Collection of solid catalyst particles dispersed in a liquid phase (slurry). The slurry is circulating at a high velocity impelled by an axial pump. The mixing pattern is very intensive and well defined. Typical application Polymerization

Bubble Columns:

Chemical Reactors and their Applications Bubble Columns Concept Gas dispersed in a continuous liquid phase. Two phases: liquid/gas. Three phases: slurry/gas Typical applications Natural gas conversion Waste water treatment Bio-processes

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Nuclear Reactor

The nuclear reactor:

The nuclear reactor Control rods Moderator and coolant (water) Steel vessel Fuel pins Pump Concrete shield Water from turbines Water to turbines

How a Nuclear Reactor works :

How a Nuclear Reactor works 235 U fissions by absorbing a neutron and producing 2 to 3 neutrons, which initiate on average one more fission to make a controlled chain reaction Normal water is used as a moderator to slow the neutrons since slow neutrons take longer to pass by a U nucleus and have more time to be absorbed The protons in the hydrogen in the water have the same mass as the neutron and stop them by a billiard ball effect The extra neutrons are taken up by protons to form deuterons 235 U is enriched from its 0.7% in nature to about 3% to produce the reaction, and is contained in rods in the water Boron control rods are inserted to absorb neutrons when it is time to shut down the reactor The hot water is boiled or sent through a heat exchanger to produce steam. The steam then powers turbines.

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