Microreaction Engineering:Is small really better?

Jan J. Lerou

Velocys, Inc., Plain City OH www.velocys.com

2

Overview

Background

Fundamentals

Reaction Applications

Scale­up Methodology

Summary

3

BackgroundHistory

•In public domain since 1995

Definition of microstructured reactors•3­dimensional structures from sub­mm to mm range•Main characteristic:

specific surface 10,000 –50,000 m2/m3

Potential benefits•Process intensification•Inherent process safety•Broader reaction conditions incl. explosion regimes•Distributed production•Faster development

4

Background (cont.)

Companies currently moving microchanneltechnology from R&D to commercialization:

•Degussa: running a demonstration project for theevaluation of microreaction technology or DEMiSTM forpropylene epoxidation with hydrogen peroxide

•Clariant: opened its Competence Centre for MicroreactorTechnology (C3MRT) to increase efficiency, improvesafety and reduce the costs of pharmaceutical synthesis­ Continuous pilot plan for the synthesis of azo­pigments

•Axiva developed a process for continuous polymerizationof acrylates (8 kg/h) using micro mixers

•Velocys…

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~ 0.1­1 mm

Microchannels enablecompact unit operations

with high capacity perunit volume by reducing

transport distances

~ 10­100 mm

Conventional

Characteristicdimension

Enabling Technology

Microchannel

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Conventional Technology

Conventional Reactors§ Steam Methane

Reformer

§ 20 millionstandard cubicfeet/day

§ ~30m x ~30m x~30m

7

Velocys® Technology Reactors

q MicrochannelSteam MethaneReformer

q Same capacity

q 90% volumereduction

q ~25% reductionin overall plantcosts

8

Microchannel Hardware Performance

< 1 W/cm21­250 W/cm2Boiling

< 1 W/cm21­20 W/cm2ConvectiveConventionalMicrochannel

Intense Heat Transfer Increases Productivity

Fast Reactions Shrink Hardware Volume

1­10 seconds1­100 msGas­phaseConventionalMicrochannel

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dkNuh ×

=Nu: Nusselt numberh:    Heat transfer coefficientd:    Hydraulic diameterk:    Thermal conductivity

Velocys Heat Exchanger Conventional Heat Exchanger

High surface area/volume ratioHigh heat transfer per volume

Low surface area/volume ratio

Low heat transfer per volume

Heat Transfer in Microchannels

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inlet outlet

Diffusion across laminar streamlines (100<Re<2000)

Mass Transfer in Microchannels

avgconvection vel

L=τ :  Characteristic convection time

L:  Flow lengthvel:  average laminar velocity

Sh:  Sherwood numberkA:   Mass transfer coefficientd:    Hydraulic diameterD:    Diffusivityd

DShkA×

=:  Characteristic diffusion time

d:  Hydraulic diameterD:  DiffusivityD

ddiff

2)2(=τ

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Mass Transfer in Microchannels

Velocys technology enhances bothintraparticle and interparticle

mass transfer

Velocys technology enhances bothintraparticle and interparticle

mass transfer

~ 0.002 cm ~ 0.2­2 cm

vs.Velocys Conventional

~ 0.02 cm ~ 0.2 cm

flow

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Low pressure drop

Laminar flow in microchannels•Orderly flow –less fluctuations

•Laminar Flow

Turbulent Flow

flowh VDfLP µ)(=

∆

Turbulent flow• Random flow –more fluctuations

•75.175.025.0)( VDf

LP

h ρµ=∆

flow

(Blasius friction factor)

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0

0.5

1

1.5

2

0 10 20 30 40 50Flow (SLPM)

Pres

sure

 Dro

p (p

si)

Experimental DPPredicted DP

Pressure Drop Case Study

48 channel deviceN2, ambientFlowtot = 40 SLPM40”x 0.035”x 0.160”Velocity = 4.2 m/sRe = 391DP = 1.47 psig (model)

DP = 1.51 psig(experimental)

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Design for Reaction Applications

Design for Constraints•Pressure Drop•Temperature / Materials

Tailor Catalyst Form•Match kinetics, heat removal, and pressure drop

Select Thermal Management Method•Convective heat transfer•Phase change•Chemical reaction

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Conventional Catalyst TechnologyPowders for stirred tank or fluidized bed applications

Extrudates for fixed­bed applications

Monoliths for gas purification applications

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Catalysts for Microchannel Reactors

Porous Metallic Felts

~0.05­0.1 cm

Microchannel Walls

Metallic Foams

Metallic Foils

Metallic Fins

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Catalyst Selection Strategy forMicrochannel Reactors

kineticsslow fast

Pressure drop and dT allowable

high

low Wall coatWall coatFin coatFin coat

Flow­byengineeredstructures

Flow­byengineeredstructures

Flow­throughengineeredstructures

Flow­throughengineeredstructures

PackedchannelsPackedchannels

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Endothermic Reaction Examples:Tailor flux and thermal profile

airfuel

reactantexhaustproduct

• Add heat by adjacent exothermic reaction• Add heat by convective heat transfer• Add heat by phase change

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Thermal Performance:Endothermic Steam Reforming

SMR Response

0.0 0.2 0.4 0.6 0.8 1.0

Normalized Distance

Com

bust

ion 

Wal

l Axi

al H

eat

Flux

 (W/c

m^2

)

SMR

 Axi

al G

as T

empe

ratu

re (C

)

Legend: Temperature Heat Flux

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High Heat Transfer to AchieveTemperature Uniformity

Temperature profile downtypical Fischer­Tropsch fixed

bed reactor∆ T 25 C

Temperature profile downfixed bed Fischer­Tropsch

microchannel∆ T 2 C

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Velocys Technology Applications

Reactions

Methane Reforming Fischer­Tropsch

Oxidation Methanol

Dehydrogenation Reactive­Distillation

Separations

Thermal swing adsorption Distillation

Mixing

Emulsions

Heat Exchange

Compact Heat Exchangers LNG

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Scale­up

q Manufacturable and Cost Effective Design

q Sufficient Flow Distribution

q Robust Operation

q Integration with Commercial Plants

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Velocys Scale­up Methodology

Full­scaleReactor

CELL

Cell•Internal channel dimensions same as

commercial chemical processor•Number of channels increase;

size of channels does not

Multi­Cell•Many channels•10­100 lb/hr

Full­Scale•>1000 channels•1000­5000 lb/hr

Full­Scale Reactor is the basicbuilding block of a commercialplant

Gas flow

MULTI

CELL

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Commercial Microchannel Reactor:Summary for Hydrogen Generation

Productivity•1MM SCFD H2 per reactor

Size•~0.6 m x 0.8 m x 0.6 m•2 tons•>5000 channels

Streams•Air ~70 ºC•Fuel ~70 ºC•Reactant  ~200 ºC•Product    ~300 ºC•Exhaust    ~300 ºC

Emissions•NOx < 10 ppm•Meets California regulations Eighth­scale DeviceEighth­scale Device

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Stacking

DiffusionBonding Machining

Shim

Manufacturable Design:Metal thinness creates microchannel dimension

Bonding creates hermetically sealed microchannelsBonding creates hermetically sealed microchannels

Featurecreation

Wall shim without features

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Device Manufacturing

27

Diffusion Bonding Large Stacks

Protocol

•Time

•Temperature

•Pressure

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Scale­up Considerations

q Manufacturable and Cost Effective Design

q Sufficient Flow Distribution

q Robust Operation

q Integration with Commercial Plants

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Tailor Pressure Drop in Flow CircuitsTo achieve sufficient flow distribution

Inlet

1 2 3

max min1

max

100%m mQm

−= ×

2 3

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Flow Distribution Validation

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Channel Flow Distribution

Sufficient flow distribution measured in test deviceSufficient flow distribution measured in test device

Run 16: 214.0 SLPM of air

0.0E+00

1.0E­05

2.0E­05

3.0E­05

4.0E­05

5.0E­05

6.0E­05

7.0E­05

8.0E­05

9.0E­05

1.0E­04

0 12 24 36 48 60 72

Channel number

Mas

s flo

w ra

te (k

g/s)

Model

Experiment

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Manifold Model vs. Experiment dP

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

0 50 100 150 200 250 300Total air flow rate (SLPM)

Inle

t pre

ssur

e (p

sig)

Model

Experimental average

Predicted manifold pressure drop matches experimentsPredicted manifold pressure drop matches experiments

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Scale­up Considerations

q Manufacturable and Cost Effective Design

q Sufficient Flow Distribution

q Robust Operation

q Integration with Commercial Plants

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Robust Performance to UpsetsRecovery after combustion lost and catalyst in situ refurbishment

Conditions:3:1 S:C23 atm6 ms CT9000 scfd H2

Reactor performance

­20%

0%

20%

40%

60%

80%

100%

0 10 20 30 40 50

Time on stream since refurbishment (hr)0

2

4

6

8

10

12

CH4 conversion (%)

Select ivit y t o CO (%)

SMR C balance (% change)

840 °C equilibrium conversion

830 °C equilibrium conversion

upset

SMR dP (psid, r ight  axis)

upse t ­  l ost  c ombust i on

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Scale­up Considerations

q Manufacturable and Cost Effective Design

q Sufficient Flow Distribution

q Robust Operation

q Integration with Commercial Plants

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Microchannel Reactor Plant Interface

Low­cost standardized reactor assemblies:•5 to 30 full­scale reactors in each assembly•Shop­built fabrication reduces

construction costs and time•Minimizes utility runs to cut

installation costs•Modular for additions

of incremental capacity.

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Summary

Microchannel technology’s advantages•Tailored thermal profiles•Optimized catalyst performance and form•Enhanced selectivity•Higher productivity•Operation near stoichiometric feed ratio

Model driven design and optimization process

Scale­up principles modeled and validated

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Contact Information

Dr. Jan J. LerouManager, Experimental OperationsVelocys Inc.7950 Corporate Blvd.Plain City, OH 43064Phone: (614) 733­3300Email: lerou@velocys.com

www.velocys.com