Slurry reactors
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This document discusses slurry reactors. It begins with introducing what a slurry is - a mixture of a pulverized solid with a liquid, often used to handle solids in bulk. It then discusses the theory behind slurry reactors, which can carry out two-phase or three-phase catalytic reactions with solids, liquids, and gases. It describes the components of a slurry reactor and different types like bubble column, Fischer-Tropsch, and batch reactors. Design equations for slurry reactors are presented. Advantages include good temperature control and potential for high reaction rates. Disadvantages include issues like abrasion and filtration. Applications include hydrogenation, polymerization, and waste water treatment. References on slurry
Slurry reactors
- 1. Presented By:- Nitin Kumar Singh MT17CML009 VNIT, Nagpur
- 2. Contents Introduction Theory 1. Construction 2.Types of Slurry Reactors Design Equation Advantages and Disadvantages Applications References
- 3. Introduction • A slurry is a thin sloppy mud or cement or, in extended use, any fluid mixture of a pulverized solid with a liquid (usually water), often used as a convenient way of handling solids in bulk. • Slurries behave in some ways like thick fluids, flowing under gravity but are also capable of being pumped if not too thick.
- 4. Theory • A Slurry reactor is a multiphase reactor system in which all the three phases i.e. Solids , Liquids and Gases can be reacted. • In the Slurry Reactors the two-phase or the three-phase catalytic reactions can be carried out. • In three –phase reactor, gas and liquid reactants are brought into contact with solid catalyst particles. • In two–phase reactor, fluid phase is usually liquid reactant in contact with the solid catalyst. • The reaction of gaseous reactant with catalyst is usually carried out in fixed bed reactor. • In three –phase slurry reactor the gaseous reactant and solid catalysts are dispersed in continuous liquid phase by mechanical agitation using stirrer. The efficient stirring ensures nearly uniform composition throughout the reactor
- 5. Reaction Steps in a Slurry Reactor : 1. Mass Transfer of Gas through Gas film. 2. Mass Transfer of Gas Through Liquid. 3. Dissolving bubble gas. 4. Mass transfer of dissolved gas through liquid film. 5. Reaction on the surface of the catalyst.
- 6. 1. Construction Reaction Tank Spargers Cooling Coils Probes Stirrer
- 7. 2. Types of Slurry Reactors • Bubble Column Reactor • Fischer Tropsch Reactor • Slurry Batch Reactor
- 9. F-T Tubular Slurry Reactor
- 10. Slurry Batch Reactor for Hydrogenation
- 11. Design Equation for a Slurry Reactor Rate can be expressed as:- rab= kgag(Cg- Cgi) = klag(Cli-Cl) = kcac(Cl-Cs) = ηkaccs and we know, cgi= Hcli 𝑟 = 𝑎 𝑐 𝐶𝑔 𝑎 𝑐 𝑎 𝑔 ∗ 1 𝑘 𝑔 + 𝑎 𝑐 𝑎 𝑔 ⋅ 𝐻 𝑘 𝐿 + 𝐻 𝑘 𝑐 𝑎 𝑐 + 𝐻 𝜂𝑘𝑎 𝑐
- 12. Where, rab = Rate of absorbtion kg= Mass transfer coefficient of gas kl= Mass transfer coefficient of liquid k = Mass transfer coefficient of solid ag= Bubble surface area ac= Surface area of the catalyst(solid) η= Effectiveness factor H= Henry’s law constant Cg= Concentration of the gas in bulk Cgi= Concentration of the gas at the interface Cl= Concentration of the liquid in bulk Cli= Concentration of the liquid at the interface Cs= Concentration of the solid catalyst
- 13. Advantages • High heat capacity to provide good temperature control. • Potentially high reaction rate per unit volume of reactor if the catalyst is highly active. • Easy heat recovery. • Adaptability to either batch or flow processing. • The catalyst may readily be removed and replaced if its working life is relatively short. • Because of high intraparticle diffusion rate, small particles can be used.
- 14. Disadvantages • Generation of fine particles by abrasion of the catalyst. • Catalyst removal by filtration may provoke problems with possible plugging difficulties on filters, further time of operation, and the costs of filtering systems may be a substantial portion of the capital investment. • Higher catalyst consumption than that of fixed - bed reactors. • Back mixed flow and the volume of the reactor are not fully utilized.
- 15. Applications • Hydrogenation of the Vegetable oil. • Polymerization of ethylene. • Waste water treatment. • Oxidation of toluene to benzoic acid. • Stack gas scrubbing with lime or magnesia. • Olefin polymerization using catalyst suspension.
- 16. Reference • Chaudhari, R. V., and P. A. Ramachandran. "Three phase slurry reactors." AIChE Journal 26.2 (1980): 177-201. • Buwa, Vivek V., Shantanu Roy, and Vivek V. Ranade. "Three‐phase slurry reactors." Multiphase Catalytic Reactors: Theory, Design, Manufacturing, and Applications (2016): 132-155. • Zhang, Xinyu, and Goodarz Ahmadi. "Eulerian–Lagrangian simulations of liquid–gas– solid flows in three-phase slurry reactors." Chemical Engineering Science 60.18 (2005): 5089-5104. • Li, Hanning, and A. Prakash. "Heat transfer and hydrodynamics in a three-phase slurry bubble column." Industrial & engineering chemistry research36.11 (1997): 4688-4694. • Beenackers, A. A. C. M., and Willibrordus Petrus Maria Van Swaaij. "Mass transfer in gas—liquid slurry reactors." Chemical Engineering Science 48.18 (1993): 3109-3139.
Editor's Notes
- #10: Catalysts are transition elements cobalt, iron, and ruthenium,nickel. (2n + 1) H2 + n CO → CnH(2n+2) + n H2O