multi-scale sustainable reaction engineering multi-scale, sustainable reaction engineering a new...

Multi-Scale Sustainable Reaction Engineering

Multi-Scale, Sustainable Reaction Engineering

A New Departmental Initiative

J. S. Dennis

Department of Chemical Engineering,University of Cambridge


Future Industrial CompetitivenessFuture Industrial Competitiveness

• manufacturing across wide range of scalesmanufacturing across wide range of scales• micro- to macro- scale• no pre-conceptions about “economy of scale”

• sustainability of processessustainability of processes• fewer by-products, higher selectivity, high purity, less

waste etc.• much improved exergetic efficiency to reduce CO2 footprint

• flexibility of operation from small to large scaleflexibility of operation from small to large scale• rapid start-up and shut-down• integration of chemical reaction and separation

• modelling and predictionmodelling and prediction• rapid design, rapid diagnosis of problems…

Reaction engineering has been neglected in recent years in many leading Universities worldwide but it remains a continuing strength for the Department,

underpinned by many new developments


Illustration by Current/ Future ResearchIllustration by Current/ Future Research

• Reactor and Reaction Efficiency

• Sustainable Energy Generation

• Transport Biofuels

• Modelling


Reactor and Reaction Efficiency


MR Multi-scale Application

Thiele modulus, 1

10–3

103

Eff

ecti

vene

ss f

acto

r,

(cat

alys

t p

erfo

rman

ce)

1

10–6

10–9

10–3 103 106 109 1012 1015

k

D~

k

k~ g

STA-2

DAF-4

Co Al P O C H

SpectroscopyPulsed Field Gradient (PFG)

spectroscopy

MRI +spectroscopyPFG

L. Gladden, M. Johns L. Gladden, M. Johns et alet al..


Trickle Bed - Product Invention

trickle flow regime pulsing flow regime transition regime

gas velocity constant at 112.4 mm/s

liquid velocity = 1.4 mm/s 8.4 mm/s 13.3 mm/s

• Hydrodynamic transition from trickle to pulsing flow occurs via local flow instabilities

• Catalyst shape can be selected to improve process operation – product launch

Velocity on superficial basis

liquid in

liquid out

gas out

gas in


Heterogeneity in Chemical Conversion and Hydrodynamics

A

B

C

10% 54%X

A B

C

-0.05 0.1vz (mm/s)Feed flowrate = 0.025 ml/min


Oscillatory Flow Mixing (OFM)

A Departmental Invention (M. MackleyM. Mackley)

Process advantages

• Controlled mixing & shear• Near plug flow• Enhanced heat and mass transfer • Homogeneous particles suspension• Multi phase mixing

Reaction Engineering application

• Continuous flow• Higher selectivity & less waste• Higher quality of products• Linear scale-up• Lower operational costs

UnbaffledUnbaffled tubetube

Baffled Baffled tubetube

Particle Particle SuspensionSuspension


Application of OFM

Large-scale reactorsLarge-scale reactors ““Meso-scale” reactorsMeso-scale” reactors

• Continuous Crystallisation• Biodiesel production• Hydrogenation• Polymerisation/Nano-particles

• Pharma. continuous flow screening• Bioprocessing

Oscillator

Syringe Pump 1

Feed tank 1

Meso-tube

Flow

Feed tank 2

Syringe Pump 2

Oscillating unit

Flow

Product vessel

Sample port

Sample port

Sample port

Sample port

Sample port

Sample port

Sample port

Sample port

Sample port

Continuous oscillatory flow meso-reactor.Nitech Solutions Ltd, Scotland

Polymer Fluids Group Cambridge


Innovation Through Electrochemistry

• Rapid Prototyping using Micro & Nanofabrication

1mm

2mm

A. FisherA. Fisher

• Microfluidic & microelectrode Microfluidic & microelectrode

devicesdevices

• continuous analysiscontinuous analysis

• integrated miniature sensorsintegrated miniature sensors

• study of reactions at interfacesstudy of reactions at interfaces (+ MRI)(+ MRI)

• controlled formation of metallic controlled formation of metallic nanoparticlesnanoparticles


Chemical Co-GenerationFisher, Gladden, DennisFisher, Gladden, Dennis

The exergetic efficiency of most catalytic reactions is poor since they are conducted far from equilibrium; there can also be significant irreversibility in subsequent heat transfer.

So, conduct them in a "fuel cell" arrangement.....

e.g. nitric acid production, sulphuric acid production......


Sustainable Energy Generation


• The challenge is to find a sorbent which The challenge is to find a sorbent which

can be reused many times.can be reused many times.

• Natural limestone (mainly CaCONatural limestone (mainly CaCO33) degrades. ) degrades.

How can it be improved, based on a fundamental How can it be improved, based on a fundamental understanding of the reactions involved? Synthetic sorbents?understanding of the reactions involved? Synthetic sorbents?

ZECA – Generation of H2 from Coal(Imperial/Cambridge)

Gasifier Reformer Calciner

4 H2

Fuel Cell

Air

CaCO3

CaO

C(s)

Work

Shift Reactor

CO + 3H2

+ H2O

CH4

2H22H2O

CO2

2H2O

J. Dennis, S. ScottJ. Dennis, S. Scott


CO + HCO + H22OO COCO22 + H + H22

COCO22 + CaO + CaO CaCO CaCO33**

* * The percentage completion of this reaction The percentage completion of this reaction

(g CO(g CO22/g sorbent) is the /g sorbent) is the carrying capacitycarrying capacity of the solid of the solid

sorbent.sorbent.

KEY REACTIONSKEY REACTIONS

CalcinationCalcinationCaCOCaCO33 CaO + CO CaO + CO22

CarbonationCarbonation

Watergas Shift Watergas Shift Separation of Separation of HH22 and CO and CO22

Regeneration Regeneration of sorbent: of sorbent:

COCO22 to to

storagestorage


HA-85-850

Number of cycles

RESULTS - NOVEL SORBENTSRESULTS - NOVEL SORBENTSC

O2 U

pta

ke, g

CO

2/g

so

rben

tNew sorbent - capacity

loss much less. Capacity increases with [CO2]

Micropore volume increases with [CO2]

Natural sorbent - uptake degrades with no. of cycles of sorption &

regeneration. Insensitive to [CO2]

Micropore volume continuously decreases

Pacciani, Müller, Davidson, Dennis & Hayhurst, A.I.Ch.E.J., paper accepted, July 2008


SIMPLE MODEL: REACTION IN PARTICLESIMPLE MODEL: REACTION IN PARTICLE

Macropore Macropore volumevolume

Micropore (BJH) Micropore (BJH) volume volume

GrainGrain (~ 200 nm)(~ 200 nm)Sorbent ParticleSorbent Particle (~ 3 mm)(~ 3 mm)

Micropore (5 – Micropore (5 – 100 nm)100 nm)

Micropores fill Micropores fill up with CaCOup with CaCO3 3

when reaction when reaction largely stopslargely stops


STEM HAADF STEM HAADF TOMOGRAPHY - TOMOGRAPHY - NanoengineeringNanoengineering

A grain from our synthetic sorbent showing pores in 5 - 50 nm range

Collaboration with Prof. Paul Midgeley, Materials Science

e.g. Midgley, P.A., Science, 309, 2195 (2005)


CHEMICAL LOOPING COMBUSTIONCHEMICAL LOOPING COMBUSTION

CH4

N2, O2 F

uel r

eact

or

Reg

ener

ator

Me

MeO

Air

CO2, H2O Fuel Reactor:

CH4 + 4/y MexOy → 4x/y Me + CO2 + 2H2O

Regenerator:

4x/y Me + 2 O2 → 4/y MexOy

Overall:

CH4 + 2O2 → CO2 + 2H2O

The exergetic efficiency of a plant using chemical looping combustion would be comparable with a conventional IGCC plant

Departmental Research: Combining in situ gasification of SOLID fuels with CuO based oxygen carrier for clean coal utilisation

J. Dennis, S. ScottJ. Dennis, S. Scott


• Suitable for range of scales for H2 production

• H2 production uncoupled from syngas production:

flexibility in fuels being gasified

provides H2 free of COx

• Upgrades low grade syngas to high grade H2.

• Pure stream of CO2 for sequestration

• Tars are destroyed

High Purity Hydrogen from Biomass via Iron Oxide Looping

Dennis & Scott (2006). A.I.Ch.E.J., 52, 3325-3328.

EPSRC Grant EP/F027435/1.


Transport Biofuels


Biomass Conversion to Fuel -Issues

• Options• (i) gasification/GTL (ii) hydrolysis/fermentation

• Need for profitability at range of scales

• Feedstock logistics/local pre-processing defines scale of processing plant

• Objectives set/managed by process modelling• LCA, cost modelling, exergy analysis, water use, logistics…

• “Food vs. Fuel” – algae?


Biodiesel Pilot Plant - New Process

• Continuous• Pressure 6 bar• Temperature ~60 C• Production 30 l/h• Frequency ~ 4 Hz• Product meets BS

EN14214• Consistent quality• V. small footprint• Economic at

intermediate scale

Reactor Section

M. Mackley, R. SkeltonM. Mackley, R. Skelton


Algal Biofuels

IssuesIssues

• Intensification

• Energy in < energy out

• Downstream extraction

• Possibly the biggest

bioreactors ever built

• Scale-up on surface area

• Integration with biological

science critical.

Dennis, Scott, MackleyDennis, Scott, Mackley


Modelling to Investigate Scale-UpModelling to Investigate Scale-Up


THEORY AND EXPERIMENT in CFBC SCALE-UP

• Observations inside a fluidised bed using Magnetic Resonance

Prediction from our recently developed computer code

Müller, Dennis, et al. (2006). Phys. Rev. Letters, 96, 15404-1 to 15404-4.

• Circulating Fluid. Beds (CUED/CanMET/TU Hamburg)• oxyfuel firing: modelling of particle motion/reaction

Müller, Dennis, Gladden et al. (2007). ICMF 2007, Leipzig

Dennis, S. Scott, D. Scott, L. Gladden Dennis, S. Scott, D. Scott, L. Gladden et al.et al.


OutlookOutlook

• new senior-level research appointment to areanew senior-level research appointment to area

• strong support from industry partners, strong support from industry partners, e.g.e.g. Johnson Matthey, Shell Johnson Matthey, Shell

• joint working on projects (exchange of personnel, industry – joint working on projects (exchange of personnel, industry – Dept.)Dept.)

• projects with Universities having key complementary skills (projects with Universities having key complementary skills (e.g. e.g. Imperial CollegeImperial College, , Queen’s University Belfast, Ohio State Queen’s University Belfast, Ohio State University, TU Hamburg ….)University, TU Hamburg ….)

LOTS TO DO..!!

multi-scale sustainable reaction engineering multi-scale, sustainable reaction engineering a new...

Documents

reaction efficiency

macro scale

large scale rapid startup

mlmin slide

plug flow

university of cambridge

new developments slide

mms liquid velocity