1 / 18

Entrained Bed Reactor

Entrained Bed Reactor. Quak Foo Lee Department of Chemical and Biological Engineering. Entrained Bed Reactor. Entrained bed, pneumatic transport reactor Riser reactor, raining bed reactor Dilute suspension of solids and usually reactors have large L/D ratio Near plug flow

acravens
Télécharger la présentation

Entrained Bed Reactor

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. Entrained Bed Reactor Quak Foo Lee Department of Chemical and Biological Engineering

  2. Entrained Bed Reactor • Entrained bed, pneumatic transport reactor • Riser reactor, raining bed reactor • Dilute suspension of solids and usually reactors have large L/D ratio • Near plug flow • If feed particles are all of the same size, them all have same residence time

  3. Entrained Bed Reactor • Advantage is one can control the residence time • Small particle and co-current flow • Simplified analysis • Flat velocity profile for gas • Plug flow of solids • Isothermal • Constant fluid properties

  4. Reactor Configurations Gas + Solid Down flow Up flow D L Gas + Solid

  5. Riser Reactor Upward particle velocity Superficial gas velocity Settling velocity of particle Gas + Solids Terminal velocity of a single particle in an unbounded fluid Note: Concentration of solids is low

  6. Terminal Velocity

  7. Reynolds Number Region Strokes Region

  8. For Higher Solid Concentrations

  9. Example • If we considered U0 ~Up, and we have 1 mol of gas reacting with 1 mol of solid of Mwt = 100 g/mol and p = 2 g/cm3

  10. For uniform gas composition • Plug flow of solids Where,  = time for complete reaction

  11. For Strokes Region and SCM • With no Mass Transfer (MT) of Product Layer Diffusion (PLD) Resistance:

  12. Critical Point Goes through a maximum at some critical R Hcrit Hmax HXs=1 Rcrit R

  13. Find Hcrit and Rcrit • Differentiate HXs=1

  14. Find Hcrit and Rcrit • Substitute Rcrit into HXs=1 to get Hcrit Note: To transport largest particles through the system:

  15. Within the Strokes Region Substitute U0 into Hcrit to get Up flow

  16. Notes • Comparison indicates Rcrit ~ 0.77 Rmax • One would do a similar calculation for any expression for τ and also can use more general equation for CD. • Note: for CA,f to be constant, e.g. at some over reactor height, we need small gas conversion (or large molar excess of species A in gas phase).

  17. Down Flow – Raining Bed Gas + Solid For some simplified case: At For chemical reaction controlling: Down flow

  18. Recall Up flow Down flow Ratio

More Related