1 / 16

Chapter 4

Chapter 4. Isothermal Reactor Design. Overview. Chapter 1 and 2 focus on mole balances on reactors to predict the volume Chapter 3 focuses on reactions Cahpter 4 combine previous chapters to obtain optimum reactor design . Design Algorithm. Mole balance (reactor type)

salim
Télécharger la présentation

Chapter 4

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 4 Isothermal Reactor Design

  2. Overview • Chapter 1 and 2 focus on mole balances on reactors to predict the volume • Chapter 3 focuses on reactions • Cahpter 4 combine previous chapters to obtain optimum reactor design

  3. Design Algorithm • Mole balance (reactor type) • Reaction rate law (reaction type, orders) • Stoichiometry (reaction coefficients) • Combine steps 1, 2 and 3 • Evaluate (integrate) either Analytically Graphically Numerically Polymath

  4. Liquid Phase Batch For the irrev, 2nd order reaction • Mole balance step • Rate law step • Stoichiometry step • Combine step • Evaluate step

  5. 4.3 CSTR For 1st order and irrev reaction • Mole balance step • Rate law step • Stoichiometry step • Combine step • Evaluate step • Damkohler number Da • Da gives the degree of conversion in flow reactor

  6. 4.3.2 CSTRs in Series • For equal size CSTRs τ1=τ2=τ operate at the same T k1=k2=k and constant ν0 • For n equal size CSTRs τ1=τ2=…=τn=τ operate at the same T k1=k2=…=kn=k

  7. 4.3.3 CSTRs in Parallel • For identical individual reactor volume, Vi, conversion, Xi, and reaction rate -rAi • The conversion by each reactor is the same as if the total feed is charged to one large reactor of volume V

  8. 4.3.4 2nd order reaction in a CSTR • For 2nd order, liquid phase reaction in a CSTR

  9. 4.4 Tubular Reactors • Consider 2nd order reaction in PFR For liquid phase For constant T and P gas phase

  10. Three reaction types A→nB • n<1, ε<0 (δ<0) → ν↓, the molecules will spend longer time and ↑X than if v=v0 • n>1, ε>0 (δ>0) ν ↑, the molecules will spend less time and ↓ X than if v=v0 • n=1, ε=0 (δ=0) v=v0

  11. 4.5 Pressure Drop in Reactors • For liquid phase reactions the pressure drop can be ignored because the effect of pressure on the concs is small. • For gas phase reactions the conc. of the reacting species is directly proportional to the total pressure • Accounting for the pressure drop is a key factor in the proper reactor operation

  12. 4.5.1 Pressure drop and the rate law • To account for pressure drop differential form design equation must be used • For gas phase 2nd order reaction in PBR

  13. 4.5.2 Flow through a packed beds • If y is defined as y=P/P0 • For a gas phase reactions in PBR of catalyst particles • α is the bed characteristics

  14. 4.5.4 Analytical solution • For 2nd order isothermal reaction with ε=0 in PBR

  15. Integrating with X=0 @ W=0 and Solving for X and W gives

More Related