Pulverization of Rubber Using the SSSE Process

Transcription

1 Pulveization of Rubbe Using the SSSE Pocess Bay Benstein, Ecevit Bilgili, Hamid Aastoopou Depatment of Chemical & Envionmental Engineeing Illinois Institute of echnology, Chicago, USA Septembe, 006

2 Outline of the pesentation Motivation behind ou pulveization and ecycling study Poduction, chaacteization, and euse of a ubbe powde: Concepts of the solid state shea extusion (SSSE) pocess Expeimental and computational heat tansfe study Summay

3 Motivation behind this study Moe than.5 billion scap ties ae pesently stockpiled in the U.S. alone; disposal chage fo ubbe waste is inceasing. Recycling methods such as micowave, ultasonic, and themal teatments degade ubbe significantly. Size eduction is a pomising ecycling technique. It does not seveely degade ubbe. Cyogenic ginding poduces fine paticles, but is expensive. Development of a non-cyogenic technology that can poduce compaably fine paticles is essential.

4 SSSE pocess: single scew extude SCREW FEEDER HEAING-COOLING ELEMENS SCREW IP COUPLING O PLASI- CORDER SCREW WIH VARYING DESIGN BARREL OF SAINLESS SEEL SOCK HERMOCOUPLES LOCAION OF CONROL HERMOCOUPLES Base-case conditions: bael wall tempeatues 135 o C, 135 o C, and 40 o C; one pass of ubbe (1SSSE) at a feed ate: 4.6 g/min; scew otation ate: 80 pm; compession atio of the scew: 5:1

5 SSSE pocess: functional zones CONROL HERMO- BARREL WALL COUPLE GRANULAES HEAING- COOLING ELEMEN SOCK HERMO- COUPLE m1 m m3 ELEMEN 1 ELEMEN ELEMEN 3 b1 b b3 Hout Ganulates Conveying Compession Pulveization OULE Hin INLE FLIGH SCREW SURFACE ZONE 1 ZONE ZONE 3 Geometic mean diamete of the feed was about 4.00 mm. Compession atio (CR) is defined as CR = H in / H out.

6 SSSE pocess: effect of compession 100 Cumulative Mass Pecent (%) 10 1 CR = 5:1 CR = 3:1 CR = 1.5: Diamete (µm) An decease in CR led to a coase paticle size distibution. he geometic mean diamete and standad deviation of the powdes wee 0.4 mm and.04, 1.33 mm and.06, and 3.30 mm and 1.4 fo the 5:1, 3:1, and 1.5:1 compession atio (CR) cases, espectively.

7 SSSE pocess: effect of tempeatue 100 Cumulative Mass Pecent (%) 10 1 b3 = 40 o C b3 = 60 o C b3 = 80 o C b3 = 100 o C Diamete (µm) An incease in bael wall tempeatue led to a coase paticle size distibution. he geometic mean diamete and standad deviation of the powdes wee 0.4 mm and.04, 0.8 mm and.0, 1.4 mm and.15, and 1.83 mm and 1.91 fo the b3 values of 40 o C, 60 o C, 80 o C, and 100 o C, espectively.

8 Heat tansfe in the SSSE pocess Efficient poduction of fine paticles depends on the success of emoving the heat dissipated in the extude. High tempeatues in the pulveization zone of the extude can cause themal degadation of ubbe paticles faste stess elaxation and consequent etadation of the fagmentation agglomeation of the fine paticles Efficient emoval of heat is impotant to the scale-up of the extude.

9 Expeimental study: ai cooling in all zones (1) s empeatues ( o C) m3 m 40 m ime (min) he cooling of the extude bael walls via compessed ai is not sufficient if the scew is not intenally cooled. he cente of the scew is the hottest spot in the extude.

10 Expeimental study: wate cooling in Zone 3 () empeatues ( o C) m s m3 30 m ime (min) he cooling of the extude bael walls via wate ciculation significantly emoves the heat geneated. But, the high adial tempeatue gadient still pevails.

11 Modeling study: geomety of Zone 3 = R5 Cooling Wate in Jacket at f, hf = R4 Bael Wall at b = R3 = R Isothemal Inlet Solid Plug Hollow Scew at s Vz Ambient Ai at a, ha = R1 Cooling Wate at f1, hf1 = 0 z = 0 z Symmety Axis z = L

12 Modeling study: simulation fo solid scew empeatue ( o C) Dimensionless Axial Distance Dimensionless Radial Distance he model pedicts the high adial tempeatue gadient in the extude. Regions 1,, and 3 epesent solid scew, ubbe, and bael wall, espectively. Simulation fo 600 s of SSSE pocessing, wate at 5 o C in the cooling jacket with h = 300 W/(m o C)

13 Modeling study: simulation fo hollow scew empeatue ( o C) Dimensionless Axial Distance Dimensionless Radial Distance 1 he use of a hollow scew within which cold wate ciculates is an efficient way fo emoving the heat geneated duing the pulveization. Regions 1,, and 3 epesent hollow scew, ubbe, and bael wall, espectively. Simulation fo 600 s of SSSE pocessing, wate at 0 o C in the cooling jacket with h = 300 W/(m o C), wate at 0 o C in the hollow scew with h = 300 W/(m o C)

14 Summay on the SSSE pocess and ecycling he SSSE pocess is capable of poducing fine ubbe paticles without employing cyogenic cooling. he paticle attibutes can be tailoed fo specific ecycling applications by manipulating the SSSE pocess vaiables. o lowe the tempeatue gadient in the ubbe, ou simulations suggest the use of a hollow scew.

15 Refeeed publications Jounal Publications E. Bilgili, A. Dybek, H. Aastoopou, B. Benstein, "A New Recycling echnology: Compession Molding of Pulveized Rubbe Waste in the Absence of Vigin Rubbe," J. Elastom. Plast. 35, (003). E. Bilgili, H. Aastoopou, B. Benstein, "Pulveization of Rubbe Ganulates Using the Solid State Shea Extusion (SSSE) Pocess: Pat II. Powde Chaacteization," Powde echnol. 115, (001). E. Bilgili, H. Aastoopou, B. Benstein, "Pulveization of Rubbe Ganulates Using the Solid State Shea Extusion (SSSE) Pocess: Pat I. Pocess Concepts and Chaacteistics," Powde echnol. 115, (001). E. Bilgili, H. Aastoopou, B. Benstein,"Analysis of Rubbe Paticles Poduced by the Solid State Shea Extusion Pulveization Pocess," Rubbe Chem. echnol.73, (000). E. Bilgili, H. Aastoopou, and B. Benstein, "Solid State Shea Extusion of Rubbe Ganules," AIChE Symp. Se. 95, (1999). Patents G. Ivanov, H. Aastoopou, E. Bilgili, N. Shahidi, and B. Benstein, "Appaatus and Pocess fo Pulveization of a Polymeic Mateial," U.S. Patent No. 6,513,737, Feb. 4, 003. H. Aastoopou, D. A. Schocke, B. Benstein, and E. Bilgili, "Pocess fo Recycling of Rubbe Mateials," U.S. Patent No. 5,904,885, May 18, 1999.

16 Modeling study: govening equations Local enegy balance fo the extude scew: Local enegy balance fo the solid plug of ubbe: Local enegy balance fo the bael wall: We imposed 3 initial conditions and 1 bounday conditions and solved the PDEs using a finite diffeence method. + = s s s s ps s 1 z k t C ρ ( )L R R f z k z V t C 3 m m m m z m pm m = + π τω ρ + = b b b b pb b 1 z k t C ρ