heat transfer processing of granular materials : application to recycled asphalt rotary kiln...

Workshop on construction and demolition waste recycling 3-5rd May 2015 Porto Alegre

HEAT TRANSFER PROCESSING OF GRANULAR MATERIALS :

application to recycled asphalt rotary kiln

Leguen L., Piton M., Huchet F.

Aggregates and Materials Processing Laboratory

http://www.gpem.ifsttar.fr/

[email protected]

http://www.gpem.ifsttar.fr/

Workshop on construction and demolition waste recycling 3-5rd May 2015 Porto Alegre2

1. CONTEXT AND SCIENTIFIC MOTIVATIONS

2. EXPERIMENTAL ROTARY KILN : ASPHALT MATERIALS PROCESSING

2.1 Recent advancement and scientific issues

2.2 Materials properties & Apparatus

5. FEW RESULTS

6. CONCLUSION & PERSPECTIVES

4. THERMAL PROCESS MODELLING

HEAT TRANSFER PROCESSING OF GRANULAR MATERIALS

3. GLOBAL ENERGY DIAGNOSTICS


Heat treatment of inorganics materials (metallurgical, cement, ceramic etc..)

Ordinary considered as not environmental friendly

Ex : Rotary Kiln working from fossil fuel (natural gases or oil) :

-carbon gas emission

-high energy consuming Ex. Clinker : 3 - 5 GigaJoule/TClinker

Energy Lost : 15 % to the wall & 40% fumes



Ex. : Thermal Treatment of mercury mine wastes using a rotary solar kiln as desorber T°C [127-600°C]

Navarro A., Canadas I, Rodrigues J., 4 37-51 Mineral 2014

Ex. : Solar calcination process

Recently, several researchers tend to revisit applications for

waste granular heat treatment:

Meier A., Bonaldi E., Cella M.G., Lipinski W., Wullemin D., Palumbo R., 29,5-6, Energy, 2004




Which sort of applications for Construction & Building Waste Recycling ?

Waste –create Bricks :

Raut S.P., Ralegaonkar R.V., Mandavgane S.A. Developpment of sustanaible construction material using industrial and agricultural solid waste : A review of waste-create bricks, Construction & Building Materials 25, 2011.

Monteiro S.N., Vieira C.M.F., On the production of fired bricks from waste materials: A critical update, Construction & Building Materials 68, 2014.

Polemic papers on that topic : which thermal processes ?

Geetha S., Ramamurthy K., Reuse potential of low calcium bottom ash as aggregate through pelletization Waste Management 30, 2010.

Geetha S., Ramamurthy K., Properties of sintered low calcium bottom ash aggregate with clay binders, Construction & Building Materials 25, 2011.

Mechanical performance with high porous structure

Pelletization of fly ash to form LightWeight aggregates :

Practical Case of the Asphalt Materials ?



Pavement after spreading

Internal view

Asphalt MaterialsAggregates [10 mm] + sand [1 mm]

+ filler [100 µm] Bituminous binder+ =

95 % 5 %

Rotary kiln equipment : Current thermal granular process in Europe, the production is equal to 300 millions of tons of asphalt concrete per year for about 5000 asphalt plants accounted

Thermosensitivity for its right spreading

asphalt plant


Right prediction of thermophysical properties of materials during its manufacturing (thermo-rheological behavior, aggregates water content, temperature prediction etc.)

Require physical knowledge during materials processing in order to ensure

Sustainable recycled asphalt materials, process and production


Sustainable pavements application :* Warm-mix- asphalt (WMA) at low temperature treatment * Recycling Asphalt Materials introduction

Hot-mix- asphalt (HMA, T°C~160 °C) quite well controlled



Asphalt

Materials

Exhaust gases~fumes

Zone 0 Zone 1

D

Combustion

Zone 2

ξ

Aggregates

Zone 3

Natural

gas

Zone 1 {D1= 1.7 m} : Heating stage Flight L-Shape(1)

Zone 3 {D3= 1.7 m} : Mixing stage Hot Bitumen spray from a rod

Zone 2 {DRMI=1.2m-D2=1.7 m} : Recycling Waste pavement Secondary air flows (2)

2. Leguen L., Huchet F., Dumoulin J. Wall Heat transfer correlation for rotary kilns with secondary air flow and recycled materials inlet Exp. Therm. Fluid Sci,, 54 110-116 (2014).

Zone 0 {D0 =2 m}: Drying stage (1)

1. Leguen L., Huchet F., Dumoulin J., Baudru Y., Tamagny P. Convective heat transfer analysis in aggregates rotary drum reactor Appl. Therm. Eng., 54 1 131-139 (2013).

RawMaterials

Recycled MaterialsInlet

2.1 Recent advancements and scientific issues



- formulation of the asphalt materialsaggregates water content- solid mass flow rates, 𝒎𝒔

- bitumen mass flow rate, 𝒎𝒃𝒊𝒕𝒖𝒎𝒆𝒏

- temperatures of bitumen, Tbitumen

- asphalt materials, TAsphalt


Recording during one year of the asphalt process production :

Asphalt ConcreteFORMULATION

Filler Crushed sand Aggregate Aggregate water content Bitumen Recycled materials

(%) 0/2 mm 2/6,3 mm 6,3/10 mm (%) Content 0/10 mm

(%) (%) (%) (%) (%)

0,95 24,81 39,26 31,21 1,58 5,21 18,96

HMA (T°Materials~165°C)

WMA (T°Materials~123°C)

HMA+ Recycled (T°Materials~165°C)



Combustion zone Heating zone

Tg (K-type)Tg (K-type)

3,860 4.360 4.860 5.860 6.860 7,8605.360

Recycled

asphalt

pavement

inlet flap

0

z (m)

0 3,000

Injection

bitumen

-

Mixing

area

3,700 4,100 4,400 5,900 6,100 6,700

Taiw1Taiw2 Taiw3

Taiw4Taof2Taof1

Rod of seven

thermal probes

Combustion flame

supplied by burner

3.860 7.860

Recycled

MaterialsInlet

0

z (m)

0 3.000

Bitumen

injection -

Mixing

area

Rod of seven

thermal probes

Combustion flame

supplied by burner

(RMI)

Combustion zone Heating zone

Tg (K-type)Tg (K-type)

3,860 4.360 4.860 5.860 6.860 7,8605.360

Recycled

asphalt

pavement

inlet flap

0

z (m)

0 3,000

Injection

bitumen

-

Mixing

area

3,700 4,100 4,400 5,900 6,100 6,700

Taiw1Taiw2 Taiw3

Taiw4Taof2Taof1

Rod of seven

thermal probes

Combustion flame

supplied by burner

3.860 7.860

Recycled

MaterialsInlet

0

z (m)

0 3.000

Bitumen

injection -

Mixing

area

Rod of seven

thermal probes

Combustion flame

supplied by burner

(RMI)

8,47 9,47

Rod of nine

thermal sensors



- fumes volumetric flow rate, 𝒒𝒇𝒖𝒎𝒆𝒔

- natural gas volumetric flow rate, 𝒒𝒇𝒖𝒆𝒍

- 9 In-situ thermal probes

CEREMA (France)FAYAT-ERMONT


Data Extraction in steady production period

0

100

200

300

400

500

600

700

800

0 100 200 300 400 500 600 700 800 900 1000

T9

T8

T7

T6

T5

100

120

140

160

180

200

220

240

500 550 600 650 700 750 800 850 900 950 1000

T1

T3

T2

T4

2. EXPERIMENTAL ROTARY KILN : ASPHALT MATERIALS PROCESSING2.2 Materials properties & Apparatus


T °C

Time (s)


0

1

2

3

4

5

6

7

8

9

1 2 3WMA withoutrecycled

HMAWith

Recycled

HMA


ENERGY SOURCE (MW)

Combustion (burner)

Hot Bitumen

As expected the lowestenergy required


20%

25%

55%

28%

15%

57%

26%

17%

57%

ENERGY SINK (%)

Heating gases

Heating grain

Drying grain

WMA HMA-R HMA



Heat Surface exchange

Tgrain(z=0) and Tgaz(z=0)

Temperature profileModelling

Heat Surface exchange

Heat transferRadiationConvection

Heat Lost

A1-D Model :

Granular distribution

Geometry of the drum

Volume of Control

ω

Active phase

Granular curtains

Boundary values

In the littérature, many papers in rotarykiln without flight

Role of the active surface with flightsand the temperature profiles of -Gas-Wall-aggregates ?


Twall, Tgrain and Tgaz


ω

Active phase

𝑚𝑔𝐶𝑝𝑔𝑑𝑇𝑔

𝑑𝑧𝑑𝑧 = − 𝑄𝑐𝑔 − 𝑄𝑏𝑔 − 𝑄𝑔𝑤

𝑚𝑠𝐶𝑝𝑠𝑑𝑇𝑠𝑑𝑧

𝑑𝑧 = 𝑄𝑐𝑔 + 𝑄𝑏𝑔 − 𝑄𝑠𝑤

𝑄𝑤𝑒 = 𝑄𝑔𝑤 + 𝑄𝑠𝑤

BASED ON :

2 nonlinear ordinary differential equations due to the radiation ΔT4

• Gas Phase :

• Solid Phase :

• Heat Wall losses:

1 closure equation to the wall



𝑚𝑔𝐶𝑝𝑔𝑑𝑇𝑔

𝑑𝑧𝑑𝑧 = − 𝑄𝑐𝑔 − 𝑄𝑏𝑔 − 𝑄𝑔𝑤

𝑚𝑠𝐶𝑝𝑠𝑑𝑇𝑠𝑑𝑧

𝑑𝑧 = 𝑄𝑐𝑔 + 𝑄𝑏𝑔 − 𝑄𝑠𝑤

𝑄𝑤𝑒 = 𝑄𝑔𝑤 + 𝑄𝑠𝑤

• Gas Phase :

• Solid Phase :

• Heat Wall losses:

1 closure equation to the wall


BASED ON :

2 nonlinear ordinary differential equations due to the radiation ΔT4


Relative error between model and experiments :

• 0.97% materials

• 5.60% gases

• 4.19% wall

Already validated with experimental well-controled production (3, 4) :

(3) Le Guen, L., Huchet, F., Dumoulin, J., Wall Heat transfer correlation for rotary kiln with secondary air flow and recycled materials inlet, Experimental Thermal and Fluid Science, 54 110-116 2014.

90-140 Tons per hour HMA without asphalt recycled and stabilizated secondary air flow

0 0.5 1 1.5 2 2.5 3 3.5 4300

400

500

600

700

800

900

1000

1100

z [m]

T [

K]

Température des solides

Température des gaz

Température de la paroi

Température solide mesurée

Température gaz mesurée

Teméprature paroi mesurée

An

ne

aud

e r

ecy

clag

ePhase gaz

Zone 1 Zone 2Phase solide

5. FEW RESULTS

(4) Piton M., Huchet F., Le Corre O., Le Guen L, Cazacliu B., A coupled thermal-granular model in flights rotary kiln: Industrial validation and process design, Applied Thermal Engineering, 75 1011-1021 (2015).

Similar trend for a large spectrum of production ?

4 5 7 8

Temperatures decay law of the gasesphases HMA without asphalt recycled

Despite a high dependance of the heattransfer coefficients

Re

cycl

ing

Intr

od

uct

ion

are

a


5. FEW RESULTS

70 experimental productions recorded during one year :

HMA-Recycled

0

100

200

300

400

500

600

700

800

900

3 4 5 6 7 8 9 10

T(°

C)

z(m)

HMA

WMA

Unusual peaks in the recycling and bitumen injection areas !


5. FEW RESULTS

Asphalt Materials

Exhaust gases~fumes

Zone 1 Zone 2

D

Combustion

Zone 3

ξ

Aggregates

Zone 4Natural

gases

0

100

200

300

400

500

600

700

800

900

3 4 5 6 7 8 9 10

T(°C

)

z(m)

Bitumen injection (T~170 °C)

Recycling Asphalt area

Specialy in the case of HMA including Recycled aggregates !


5. FEW RESULTS

An adapted model is required for the Recycling Area

Equivalent to an agitateddense granular regime

Thermal storage within virgin materialsredistributed to the gases

Large amount of materials introducedin small space (smaller inner diameter)

ξ

Cold RCA

Hot areaCold area


Dense Granular regimeMixing : Hot virgin aggregates

Hot gasesFresh Recycled Asphalt

Asphalt Materials

Exhaust gases~fumes

Zone 1 Zone 2

D

Combustion

Zone 3

ξ

Aggregates

Zone 4Natural

gases

-Similar energy consumption with or without Recycling Asphalt Materials

6. CONCLUSION & PERSPECTIVES

-As expected WMA gives the best energy consumption

-Heat transfer processing are quite well simulated by a 1-D model in the Zone 2 and 3 without Recycling Materials

- With Recycling Materials, temperature evolution is unusual :

Thermal model requirement at the Recycling Position


THANK YOU FOR YOUR ATTENTION

heat transfer processing of granular materials : application to recycled asphalt rotary kiln...

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