week # 5 mr chapter 6 fluid flow through a packed bed of particles

Week # 5MR Chapter 6

Fluid Flow Through a Packed Bed of Particles

• Tutorial # 5• MR #6.1, 6.3, 6.5, 6.7,

• To be discussed on Feb. 17, 2016.• By either volunteer or class list.

MARTIN RHODES (2008) Introduction to Particle Technology , 2nd Edition. Publisher John Wiley & Son, Chichester, West Sussex, England.

Pressure drop-flow relationship

/U Ui Tube equivalent diameter:

Hagen-Poiseuille:

Laminar flow:

2eH K H

Flow area = A; wetted perimeter = SBA;SB: Particle surface area per unit volume of the bed.Total particle surface area in the bed = SBAH

For packed bed, wetted perimeter = SBAH/H = SBA

Darcy (1856)

Carmen-Kozeny eq:.

Turbulent flow:

(1 )v BS S

A

Sv = 6/x

General equation for turbulent and laminar flow

Ergun eq.

Non-spherical particles

Friction factor versus Reynolds number plot for fluid flows

through a packed bed of spheres

Filtration

• Incompressible cake

(Eq. 6.21, See Appendix 5 for derivation )

(From Ergun equation)

• Constant pressure drop filtration

• Including the resistance of the filter medium

(Eq. 6.23, see Appendix 5 for derivation )

(Eq. 6.27, see Appendix 5 for derivation )

Washing the cake

Removal of filtrate during washing of the filter cake

Compressible cake

Analysis of the pressure drop-flow relationship for a compressible cake

rc = rc(ps)

xsv = 792 m.