pressure drop in water gas shift reactor (jason keith)

8/10/2019 Pressure Drop in Water Gas Shift Reactor (Jason Keith)

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CACHE Modules on Energy in the Curriculum

Fuel Cells

Module Title: Pressure Drop in a Water Gas Shift Reactor

Module Author: Jason Keith

Author Affiliation: Michigan Technological University

Course: Kinetics and Reaction Engineering

Text Reference: ogler !"thedition#$ Section "%&

Concepts' Use the Ergun e(uation to deter)ine the pressure drop *ithin a *ater+gas shift

reactor%

Problem Motiation:

uel cells are a pro)ising alternative energy conversion technology% ,ne type of fuel cell$

a proton e-change )e).rane fuel cell !PEM/# reacts hydrogen *ith o-ygen to produceelectricity !igure 0#% unda)ental to a hydrogen econo)y po*ered .y fuel cells is the

generation of high purity hydrogen%

/onsider the sche)atic of a co)pressed hydrogen tan1 !2333 psi$ regulated to 03 psi#

feeding a proton e-change )e).rane fuel cell$ as seen in igure 2 .elo*% We *ill no*

focus on deter)ining the pressure drop in a *ater+gas shift reactor$ *hich is used togenerate hydrogen to .e used in fuel cells%

0stDraft J%M% Keith ,cto.er 23$ 2334

2nd Page 0 March 05$ 2336

72tan1 uel /ell

/o)puter

!Electric

8oad#

72out

9ir in

9ir : 72, out

igure 2% Diagra) for fueling a laptop%

Pressure

regulator

72feed line

8,W /79;;E8S8,W

/79;;E8S

H2

H2

H2

H2

H2

O2

O2

H+

e-

e-

AnodeElectrolyte

Cathode

O2

H2O

H2O

O2

H+

H+

H+H2

H2

H2

H2

H2O

H2O

8,W /79;;E8Sigure 0% Reactions in the PEM/


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!ac"ground

;atural gas has .een proposed as a source of hydrogen for fuel cell vehicle applications.ecause of the e-isting infrastructure%


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Ac$ cross sectional area !ft2#

c$ solid catalyst density !l.):ft?#

Definingy@P:Po$ E(uations 0+? can .e co).ined together$ *ith so)e alge.ra$ to yield'

ydWdy

2= !"#

*here and oare constants and are given .y'

occ

o

PA

#0!

2

= !

and

+= GDDgG ppco

o 5&%0#0!0&3#0! ? !A#

The first ter) in the .rac1ets is do)inant for la)inar flo* and the second ter) is

do)inant for tur.ulent flo*%

E(uation " can .e integrated to yield the reactor e-it pressurePfro)'

2:0#0! WP

P

o

= !5#

Thus$ for an isother)al reaction *ith no change in )oles$ the pressure drop can .edescri.ed .y E(uation 5% or )ore detail on this derivation$ see page 04? in Section "%&

of oglerBs te-t%


2nd Page ? March 05$ 2336


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2"

2

2

ft03&%4

ft

c)"4%?3

c)0

""

=

== reactorcD

A !03#

The feed pressure in l.f:ft2is'

2

f

2

22

f

ft

l.03A33

ft

in0""

at)0

in

l.A6A%0"

at)&=

=oP !00#

The catalyst *eight in l.)is'

)) l.305%3g"&"

l.g&%5==W

!02#

Thus$

2

2

f

?

)2"+

)?

f

033%"

ft

l.03A33

ft

l.5A#&%3!ft034%&

#l.305%3#!ft

l."0"!2

#0!

2

=

=

=

occ

o

PA

WW

!0?#

The e-it pressure can .e deter)ined fro) E(uation 5 as'

64%3#0! 2:0 == WP

P

o

!0"#

Analysis' Since Po@ & at)$ the e-it pressurePis e(ual to "%6 at)% Thus$ the pressure

drop is a.out 3%0 at) !0%& psi# in the la.oratory reactor% This is relatively negligi.le%


2nd Page & March 05$ 2336


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Home Problem #tatement: /onsider an industrial scale *ater+gas shift reactor in a

tu.ular pac1ed .ed of 03 c) dia)eter *ith A3 1g catalyst%

pressure drop in water gas shift reactor (jason keith)

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