Recent Innovations in Sustainable Drying Technologies

Prof Arun S Mujumdar

McGill University, Montreal, Canada

University of Queensland, Brisbane, Australia

NIFTEM, Kundli, India

KMUTT, Bangkok, Thailand

www.arunmujumdar.com September 2017

Sustainable Drying Technologies - Role of Global R&D

可持续干燥技术 - 在全球研发中的作用

Professor Arun S Mujumdar McGill University, Montreal & Western University, London, Canada

加拿大 麦吉尔大学 和 西安大略大学 Honorary Professor, Jiangnan University, China

荣誉教授，中国 江南大学 Plenary Lecture, ADC2017, Wuxi, China

September 2017

www.arunmujumdar.com

Introduction – Role of ADC/IDS/LDRT – Vison/Mission

Innovation – Needs and challenges Selected innovations

o SHSD (Superheated Steam Drying) o Pulse Combustion Drying o DIC/Swell Drying o Flame Drying o Miscellaneous

Closing remarks

To provide a global forum for exchange, transfer of ideas, knowledge on drying

To encourage industry-academia transfer of knowledge, knowhow and technology

Develop a truly inter- and cross-disciplinary forum across geopolitical and industrial sectorial boundaries

Establish a new research discipline of Drying R&D combining transport phenomena with material science

To promote innovation essential to have a central location to disseminate knowledge, exchange ideas and network globally

Short answer: Qualified, yes With over 4000 papers from 80+ countries over four decades

IDS has contributed to the technical literature in drying. IDS spawned many other similar fora e.g. ADC, AIDC, WFCFD

and stimulated others like NDC, CDC, Nigerian DC. Let to the only archival peer-reviewed journal devoted to

drying and dewatering – Drying Technology – An International Journal

It is relevant to look into the history of the journal at this point.

Following statistical information available on ASM website: www.arunmujumdar.com

Montreal (3) Birmingham

Kyoto Boston Prague

Versailles

Gold Coast

Beijing

Noordwijkerhout Kraków

Thessaloniki Sao Paulo

Bali Penang

Bangkok (2)

Sao Paolo

Montreal

Veracruz

Kolkata Trondheim

Copenhagen Karlstad

Mumbai (11)

Budapest

Gifu

KL

IDS ADC NDC IADC IWSID/ WFCFD

Hyderabad

Iceland Tianjin

Hong Kong

Xiamen

Magdeburg

Lyon

Wuxi

A few authors made massive contribution of papers, reviews – Pereto principle – 20% contributed 80%

Over last decade situation has turned around but for quality assurance dedicated referees are the “key” to success – still a challenge due to heavy manuscript flow

Latest Impact Factor (2016) – 1.98

Latest 5 year Impact factor (2015) – 2.006

True impact in industrial application

No of papers since 2005 - ∼2318

No of authors per volume since 2005– ∼300

No of countries/territories contributing to LDRT (All years) – 105

Projected Impact Factor for 2016 – 2.0+

Source: ISI Web of Science (last accessed on Aug 1, 2017)

Some statistics on LDRT (1982 – 2015)

Year Impact factor

2016` 1.98

2015 1.85

2014 1.52

2013 1.74

2012 1.81

2011 2.08

2010 1.66

2009 1.05

2008 1.39

2007 1.17

2006 1.10

2005 1.03

Two-year impact factor of Drying Technology

Source: ISI Web of Science (last accessed on Aug 1, 2017)

Country No. of papers published

China 479

Canada 397

United States 316

France 281

Brazil 266

Australia 260

Poland 226

Japan 215

Singapore 171

Thailand 168

India 159

Germany 123

Turkey 112

Top contributing countries during 1982-Present (Only RESEARCH articles)

Source: ISI Web of Science (last accessed on Aug 1, 2017)

Author Name No. of papers published

Mujumdar, A.S. 222 Zhang, M. 83 Langrish, T.A.G. 60 Soponronnarit, S. 60 Chen, X.D. 54 Freire, J.T. 42 Raghavan, G.S.V. 41 Maroulis, Z.B. 40 Kudra, T. 37 Perre, P. 35 Prachayawarakorn, S. 34 Lee, D.J. 33 Zbicinski, I. 31

Top contributors during 1982-Present (Only RESEARCH articles)

Source: ISI Web of Science (last accessed on Aug 1, 2017)

Arun S Mujumdar (Editor-in-Chief)

Sakamon Devahastin

(Senior Associate Editor)

B. Adhikari; Takeshi Furuta; Tadeusz Kudra; Timothy A.G. Langrish and C.L. Law

(Associate Editors)

Sachin V Jangam; Agus P. Sasmito; Meng W. Woo; Zhonghua Wu and Azharul Karim, Hong Wei

(Assistant Editors)

22 EAB members from 16 countries 3000+ authors from 100+ countries 185 papers published in 2015

27 review papers published in 2012-2015

A Brief SWOT Analysis Strengths Globalized, multi-disciplinary, multi-industry

forum with huge opportunities for innovation Weaknesses Highly interdisciplinary; applied discipline;

Options/ Opportunities

Broad range of problems in drying/dewatering with over 10000 materials in several hundreds of dryers . Huge opportunities for enhancing efficiency, quality, environmental impact

Threats As applied discipline must benefit industry/society. Technology transfer is key. Must attract active industry participation. A real challenge. Threatens innovation.

S

W

O

T

Introduction - What is innovation? Novelty, Renovation versus Innovation

Why Innovation? Incremental vs Radical

Technology Development via Industry-University Collaboration

Time scales of Innovation in Drying-Academia-Industry appear to be a mismatch

Innovative dryers-most are at lab and pilot scales-Need to develop reliable scale-up and LCA models

New product or process

Higher capacities than current technology permits

Better quality than currently feasible

Reduced overall cost

Reduced environmental impact, sustainable

Safer operation; more flexibility

Better efficiency

Quality trumps energy saving currently

Innovative dryers for particulates

Modified Fluid Beds

Impinging Streams

Vibrated

Modified spouted beds

Agitated Mechanically

Pulsed Air

Periodic localized Fluidization

Superheated Steam

Pulsed

2D

Superheated Steam

Mechanical fluidization

SB driven by pulse combustor

2D

Complex Geometries

Superheated steam

Vortex Type

Classification of Innovations

Based on way heat is supplied

Multi - staging

•Steady

•Periodic

•on/off

•Combination of different modes - concurrent or sequential

•Conventional or innovative dryers in multi-stage arrangement

Cyclic Operation

•Pulsed fluidization or spouting

• Steady thermal energy impact

• Constant gas flow

• Single mode of heat input

• Single dryer type – single stage

• Air/combustion gas as convective medium

Conventional Innovative

• Intermittent energy input

• Variable gas flow

• Combines different modes of heat input

• Multi-stage; each stage maybe different dryer type

• Superheated steam drying medium; flame drying

Developments in Drying A Coarse Classification

Developments in Drying Coarse Classification

Empirical (> 90% published work)

Modeling Drying

*Modeling Dryers

Lab Scale

Pilot Scale

** Industrial Scale

• Microscopic • Macroscopic • Analysis /

scale-up / Control

• Smart dryers

> 80% ~ 10% ~ 10%

* Dependent on dryer type and material

** Unpublished; difficult to guestimate

Industrial Drying - Innovations

Incremental Evolutionary

Radical / *Revolutionary

• Low risk • Hybrids of known

technologies • More accepted by

industries

• High risk • Not readily

accepted • High R&D cost

* Game changing technologies - few

Long half-life of drying technologies attracts less R&D. ROI on R&D investment not attractive in most sectors

Coarse Classification of Innovations in Thermal Dryers

How wet material is handled

Miscellaneous

• Stationary • Moving • Agitated • Vibrated • etc

• Convection • Conduction • Radiation • MW/RF • Combinations /

Concurrent / Consecutive

• Intermittent

How heat is supplied to dryer

• Hybrids • Multi-staging • In-situ heat

generation – Rema flam / Flame Drying

• Pulse Combustion Drying

• Superheated Steam Drying

Intensification Techniques for Fluidized Beds

Internal heat

exchangers

Vibration

Agitation

Microwave

field

Pulsation of

Flow

Rotating bed

Superheated steam

Some techniques used to enhance efficiency e.g. intermittent fluidization; low pressure fluidization, may decrease the drying

rate but contribute to improved product quality

Variable operating parameters: pulsating gas flow, variable temperature, adjustable heat input or periodic fluidization

energy and cost effectiveness Pulsating – provides vertical vibration, improving

the fluidization quality Bed temperature - batch FB - constant - adjustable

heat input Pulsating FB –rotated hot air inlet – intermittent

drying times

Pulsating Fluidized Bed

low energy consumption due to high specific moisture extraction rate (SMER)

high coefficient of performance (COP) wide range of drying temperature (-20 0C to 110 0C)

and humidity environmental friendly high product quality. suitable for heat sensitive products (food, bio-origin

products.

Fluid Bed Heat Pump Dryer

Homogeneous FB without channeling or bubbles; high gas velocity possible Deeper bed depth is possible if the bed is agitated-Not commonly used

• Centrifugal / rotating FB - flowing gas radially - rotating cylindrical perforated distributor.

• Promising, contacting Umf and Ut can be controlled

Variant Conventional Modified FBD

Mode of heat transfer

Only convection Convection + conduction (immersed heaters in bed) + radiative heat transfer (MW assisted fluid beds)

Gas flow Steady Pulsating; on/off

Mode of fluidization

Pneumatic Mechanically agitated / vibrations

Drying media Air / flue gases Superheated steam / heat pump assisted (even using inert media)

Type of material dried

Particulate material Drying of pastes / slurries using bed of inert particles

Developments in fluid bed drying (comparison Modified and conventional fluidized beds)

Some Recent Innovations*

Inclined Blade Paddle Dryer TSK, Japan

Pulse Combustion Dryer

• Sludge • Pastes

• Textile • Liquids

Remaflam / Flame Drying

• Liquids

DIC / Swell Drying

• Illustrative only, No commercial endorsement is intended or implied

• LCA, Sustainability not examined for most innovations yet

Enhancement of Drying Rates Vibration (e.g. Vibrated bed dryers) Pulsations (e.g. Impinging jets) Sonic or ultrasonic fields (e.g. pulse combustion

dryers) Dielectric fields {MW, RF} (e.g. MW-assisted steam

drying) Superheated steam drying Cost effectiveness not known for most cases

Vacuum steam dryers for wood*

Vacuum steam dryers for silk cocoons**

Fluidized bed dryers for coal*

Impingement and/or through dryer for textiles, paper***

Flash dryers for peat (25 bar)****

Conveyor dryers for beet pulp (5 bar)****

Fluidized bed dryers for pulps, sludges*

* Extensive commercial applications ** Laboratory scale testing *** Pilot scale testing ****At least one major installation

Superheated Steam Dryers

Near Atmospheric Pressure High Pressure Low Pressure

• Flash dryers with or without indirect heating of walls

• FBDs with or without immersed heat exchangers

• Spray dryers • Impinging jet dryers • Conveyor dryers • Rotary dryers • Impinging stream dryers

Fluid bed

Possible Types of SSD

Devahastin et al., Drying Technol., 22, 1845-1867 (2004)

Photographs of carrot cubes underwent LPSSD and vacuum drying

SEM photographs of carrot undergoing (a)LPSSD, (b) vacuum drying

SEM photographs showing pore distribution of carrot undergoing (a)LPSSD, (b) vacuum drying

Devahastin et al., Drying Technol., 22, 1845-1867 (2004)

• Pulse combustion is intermittent ; can be subsonic or supersonic Mach

Number >1.0 (supersonic) Features Steady Pulsed

Combustion intensity (kW/m3) 100-1000 10000-

50000 Efficiency of burning (%) 80-96 90-99

Temperature level ( K) 2000-2500

1500-2000

CO concentration in exhaust (%) 0-2 0-1

NOx concentration in exhaust (mg/m3) 100-7000 20-70

Convective heat transfer coefficient (W/m2k) 50-100 100-500

Time of reaction (s) 1-10 0.01-0.5 Excess air ratio 1.01-1.2 1.00-1.01

http://blastwavejet.com/pulsejet.htm

• High drying rates

– Increased turbulence and flow reversal in the drying zone promote

gas/materials mixing

– Decreased boundary layer thickness of materials

– Increased heat and mass transfer rates

– High driving force because of high gas temperature

• short contact time

– Suitable for some heat sensitive materials

• High energy efficiency and economic use of fuels

• Environmentally friendly operation

• Noise and scale-up issues

Dryers Typical evaporation capacity

Typical consumption (kJ/kgH2O)

PC dryers 250-2000 kg H2O/h 3000-3500

Tunnel dryer 5500-6000 Impingement

dryer 50 kg H2O/hm2 5000-7000

Rotary dryer 30-80 kg H2O/hm2 4600-9200

Fluid bed dryer 4000-6000

Flash dryer 5-100 kg H2O/hm3 4500-9000

Spray dryer 1-30 kg H2O/hm3 4500-11500 Drum dryer

(pastes) 6-20 kg H2O/hm2 3200-6500

• limited industrial data • Very promising technology

PC Spray dryer

PC Atomizer

of egg white

Product quality-pysical properties

Product color

PC spray drying Tradiational spray drying

White pale yellow

Product quality-pysical properties Product morphology

PC spray drying Tradiational spray drying

1. Hallow 2. Single 3. Soomth surface

1. Solid 2. Aggrigated 3. Coase surface

Apply step-wise change in operating conditions for batch drying

Especially final stage of drying – drying rates are sluggish (diffusion controlled) hence effect of external conditions is negligible

Use – stepwise change in operating conditions to save energy

Use – Combinations of modes of heat input Concept can be applied for different drying methods – tray

dryer, FBD, conveyor dryer etc. Flipping of product-expose wetter surface to drying agent

Classification of Intermittent Dryers

ON/OFF Type

Examples:

Pulsed fluidized beds

Pulsed heat pump drying

Cyclic

Examples:

Fixed/variable frequency

Multi-flash drying

Heat pump drying

Step-wise

Examples:

Convective drying of foods with step-wise change in operating conditions

Random Variations

Examples:

Use of hybrid heat inputs at random time as required

Some examples of Intermittent Drying

Rotating Jet Spouted Bed dryer

Pulsed bed - intermittent fluidization

Vibrated bed with tempering periods

Intermittent IR/MW in a batch heat pump dryer

Conveyor (Apron) dryer with parts of the dryer unheated

Aside from reduced energy/air consumption, product quality may be better for heat-sensitive and/or fragile solids. Slight increases in drying time are expected

MW Freeze drying • microwave can heat the material volumetrically; thus, greatly improving

freeze drying rate is possible • most promising techniques to accelerate drying and to enhance overall quality • Examples – Cabbage, marine products, banana chips, potato, skim milk

T

Cold trap

Vacuum Pump

MW freeze drying chamber

MW sourcefreeze drying chamber

• Flash + Fluid bed• Fluid bed + Packed bed • Vacuum + MW• Well-mixed fluid bed + plug flow fluid bed dryer

• Convection dryer + Vacuum frying

Some Hybrid Dryers

Liquid/ Paste Sheets (e.g. fruit leather)

Particulate, Granular products

• Spray + Fluid bed• Spouted bed or

fluid bed of inert particles

• Impingement + IRRadiation

• Fluid bed of inertparticles

Drying is highly energy intensive hence it adversely effects environment, plus good quality is needs to be maintained for foods – need for smart/intelligent dryers

Use mathematical models, advanced sensors and automatic control strategies to design smart dryer

A smart dryer: o Provides actionable information regarding the performance of the

drying system o Proactively monitors and detects errors or deficiencies in dryer

operation o Incorporates the tools, technologies, resources and practices to

contribute to energy conservation and environmental sustainability.

Designed to sense local drying conditions/product properties and adjust them in order to get specified quality at optimized energy consumption.

Industry-academia collaboration with tangible industry collaboration

Global networking – pool human and financial resources. Also promotes innovation and avoids duplication

Develop reliable math models to study innovative concepts before physical testing

Study carefully archival literature and conference papers for ideas and also collaborations

Crowd-sourcing to seek innovative ideas – often very successful

Despite low energy cost – R&D for innovation is needed

Quality, Carbon footprint are driving forces Better models for drying and dryers are still needed Industry collaboration is critical for technology

transfer LCA, sustainability analysis is recommended for all

innovations.

Books /monographs by Prof. Arun S. Mujumdar During 2009-2014

Visit us at: http://www.arunmujumdar.com/

Best wishes to all participants for a pleasant stay in Wuxi, and for a

professionally rewarding conference

Visit: http://www.arunmujumdar.com/ for details