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Batch Reactor
The document provides a comprehensive overview of batch reactors, including their working principles, advantages, disadvantages, and various design considerations. It discusses the importance of mean residence time, material, and energy balances, as well as the kinetics involved in batch processes. Additionally, it highlights applications suited for batch reactors, particularly in scenarios requiring small production quantities or during developmental stages.
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Batch Reactor
- 1. Batch Reactor M. AwaisYaqoob 2011-ch-32 (University of Engineering and Technology, Lahore)
- 2. Mean residence time(t) • It is taken as the measure of the performance of batch reactor t =v/υ= volume of reactor Flow rate of feed in the reactor
- 3. Synopsis Introduction Working principle Advantages anddisadvantages Applications • Rate equation • Material balance • Energy balance Kinetics Design steps
- 4. Introduction Working Principle Advantages limitations 1st Part Material Balance Performance Equation Energy Balance kinetics 2nd Part Designsteps Factors Design of BR problem 3rd Part
- 5. Reactor Design Size ofreactor • Fix one of the 5 parameter • Vf • Ws • S • Vs • Vr • Shape • Spherical • cylindrical • Dimensions • Internals • Inlets & outlets Type of reactor •BR •CSTR •PFR •Fixed bed reactor •Fluidized bed reactor •Slurry reactor Method of operation • Batch • Continuous • Semi- Continuous • Intermittent
- 6. Method of Operation Thermodynamic Basis •Isothermal • Adiabatic • Constant Volume • Constant Pressure Flow Patern • Counter • Co Current • Cross Current Arrangment • Series • Parallel • Recycle • Or Combination Of Above
- 7. Introduction • The reactantsare initially charged into a container, are well mixed, and are left to react for a certain period. • The resultant mixture is then discharged.
- 8. Working Principle • Abatch reactor has neither inflow nor outflow of reactants or products while the reaction is being carried out • This is an unsteady-state operation where composition changes with time; however, at any instant the composition throughout the reactor is uniform
- 9. Advantages • They arepreferred for establishing or verifying kinetics because they are o Simple in construction o Require little or no auxiliary equipments • Data can be collected easily if Isothermal reactions are carried out under constant volume condition • High conversions
- 10. Disadvantages/limitations • Intensity ofprocess is localized and not the global one • Preferred for homogenous reactions only • high labor costs per batch • difficulty of large-scale production. • Long idle time (Charging & Discharging times) leads to periods of no production • No instrumentation – Poor product quality
- 11. Application • Typically forliquid phase reactions that require long reaction times • Used only when small amount of product is required • Favored when a process is in developmental stage or to produce expensive products • Used to make a variety of products at different times
- 12. Material Balance • Alsocalled mass balance. • Is an application of law of conservation of mass for the analysis of physical systems. • It states that: • The mass that enters a system must, by conservation of mass, either leave the system or accumulate within the system
- 13. Performance equation (ṁA)in -(ṁA)out + (ṁA)gen - (ṁA)cons= (ṁA)acc/dep since (ṁA)cons - (ṁA)gen = (ṁA)net cons In case of BR (ṁA)in and (ṁA)out = 0 The above equation will become -(ṁA)net cons = (ṁA)acc/dep Dividing the above equation with molar mass of component A
- 14. • -(ṄA)net cons= (ṄA)acc/dep Since After Substituting these values we will get
- 15. • Rearranging andintegrating will give
- 16. Corollary • If thedensity of the fluid remains constant, we obtain
- 17. Energy Balance • Itis the application of law of conservation of energy for the analysis of our physical system under consideration • The heat that enters a system must, by conservation of heat/energy, either leave the system or accumulate within the system • Overall energy balance • heat in – heat out + heat gen – heat cons = heat acc/dep
- 18. Kinetics Rate Law ForZero Order Reaction • Assumptions: o Isothermal o constant volume o irreversible reaction Stoichiometry: Assumed rate law:
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- 22. Third order • Irreversibletrimoleculer • A + B + D products
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- 24. Design Steps FACTORS • TypeOf Reaction • Scale Of Prodution • Cost Of Equipment And Operations • Safety • Stability • Life Expectency • Ease Of Convertibility
- 25. Design steps • Thereis no particular formula for selecting the parameters of a reactor •Experience •knowledge of characteristics of reactors •literature survey Helps us in selection of parameters
- 26. A Typical BatchReactor
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