The Improvement of Cake Filtration Rate using CO 2

Korean Chem. Eng. Res., Vol. 44, No. 5, October, 2006, pp. 468-475 m ( ) i m m i m m Ç i p 402-751 p}e n 253 (2006 3o 6p r, 2006 6o 26p }ˆ) The Improvement of Cake Filtration Rate using Gas Saturation Sung Sam Yim Gand Yun Min Song Department of Environmental Engineering, Inha University, 253, Yonghyun-dong, Nam-gu, Inchon 402-751, Korea (ReceivedG6 March 2006; accepted 26 June 2006) k h k p p l p l l k p v l p eˆv. p n p k p l ~ mp p p e dense skin(, Ã Ã)p l p p p n p. er k p p p l l l eˆ o p ll. l l l kp l sq rl d e nkl k p d k p l ~ ˆ l l qp p, p p l l e ˆ p l l m. Abstract For the filtration of super compactible cake, the high filtration pressure can not improve filtration rate. As the high pressure, in this case, decreases the cake porosity adjacent to filter medium and thus forms 'dense skin' which decreases the rate of liquid flow in a great extent. Actually, there was no method to improve filtration rate for the filtration with super compactible cake. We propose the saturation of gas into the suspension before the filtration operation for improving the filtration rate. The dissolved gas transforms itself into gas phase in the dense skin through which the pressure changes dramatically. The gas secures its space inside the dense skin, and finally forms the flow passages which improve the filtration rate. Key words: Cake Filtration, Compressible Cake Filtration, Dense Skin, Filtration with Gas Saturated Suspension 1. p l p p 50l p rp p l. 1953 Tiller l p p k l p l p p l p p eq [1]. p p p k n l Tiller 1962 l p p mp [2], p p 1973 l k p n p p p l p l dense skin(, Ã Ã)p p rk m [3]. p p l p (floc)l m p n k p p p l p n l ~m r p l p q p q eˆv k p. p p vp p p p v [4]. ~w, p v kp p kv To whom correspondence should be addressed. E-mail: yimsungsam@inha.ac.kr sq v kp, p p r~p 5~10Í r v. w, l k p v eˆ p r v. l ~l r p v. w, p k l p v p p p l p r~p r p v. w, k p v l p v ˆ v k. w, k p v l p m p p p n kp p k l p l p qp p v k. rp k p n p l l p k l l vv kp, p p p v v k. r p k p v p l p l l l k p p k l p l l v, pp r p p lp p. q v p k p vp l l l vveˆ o on p re v p erp. l l p p rp l e rp p 468

kl r p e m. l q ˆkl d tp l eˆ l eq. lkp p ns d p p l k pl p ~ ˆ r l p r p kp l qp p e p p p. l l p ˆkl d tpl p p p l m p p sq k p p p l eˆ o n p re p v p q m. d n p v d 3.3 p kp l k keˆ p ~ p. l l n p kp l r p kp k. 1 m 3 p ˆkp } o dp kp 1 kl 23 mol p dp kp k 33 mol q., n dp. k p p l l eˆ o l sr n, p v p l sr ~ lk l r p p eˆ p p m r k v ep [5]. p n l srp ~ p l vp l l r p p p p l. l sr k p vp r~ l v eˆ l vp p. 2. m 2-1. Ruthm i m m i m p l (cake filtration), l sqp l ~ l pq p p l p v l. p p l p l l Darcyp e[6]p (1)ep n. dv ------ = q = dt p ---------------- c µα av W l V l o r lkp (m 3 /m 2 )p, t l e (s), q lkp ˆ (m/s), p c p ky p k p p(pa), µ lkp r (kg/ms), α av p r (m/ kg), W l o r p p v (kg/m 2 )p. p ep Darcy[6] e mr p v kp p p l pp l l Darcyp ep. p (1)ep l l rn r~k pm l ~p r R m p n l pp e (2). p ˆ ( ) dl p p l p 469 (1) p lp p. ρs W = --------------------- V 1 S S c l ρ lkp p, S ˆkl p ~ v, S c p p ~ v p. p ep o lk o p p v p C rp, W = CV, k p ep. C W ---- ρs = = --------------------- V 1 S S c l v k lkp ρ n p l p C ˆkp ~ v Sm p p ~ v S cl p r. p (2)el p Ruthp ep (5)ep. dv ------ dt p = ------------------------------------ µ ( α av CV+ R m ) p (5)ep lp r, pp ep. dt ------ dv t G ------- = --------------- V + ------ µ R (6) V m p p µα av C (6)el p l r p p p. l e p l l e l lkp r r l p t / V, p V p l. pv l l t r n n k e v p ˆ. p Fig. 1l ˆ l. (6)el p Fig. 1p v n b µα av C/ p ˆ. l e l n bm r (µ), C l k p n l l r α av p p. l e l p r~p r p r p r p r v rp tp k. pr p v vr r p pp 2-2rl p. Fig. 1l p l r r p p 80 l ~ lp n p. Yim[7]p l v rl l kl (3) (4) (5) dv ------ dt p = ------------------------------------ µ ( α av W + R m ) l eq l l ~ ol p v k kp (2)el o r p p v W sq v k. p p l l ~ lkl l p pq p l ~ ol p. o r p p v p o v v ˆ, ˆk r~p v p p p v lkp v p, k (2) Fig. 1. Typical result of filtration experiment. Korean Chem. Eng. Res., Vol. 44, No. 5, October, 2006

470 p Ë l rp pl nl p p n l p. (6)ep v p Fig. 1p e nlq l y r p. v, r p µr m / pl lkp r m l k p n l R m p p. p 80 p n pp Yim [8, 9]p p l rrp re p m. 2-2. m m (constitute equation of cake) p p vp k o k -Œ q (compression-permeability cell; CPC) e (7)e (8)ep. CPC p p pql vr p ~ k k (p s )p tl e p, p p v p e p p r. p s l kt qp k~k p p Œ e r Œ o l p p r (α)p. α = ap s n β 1 ε = Bp s p el ε[ ]p CPC l p p p p, α[m/kg] p εp v p p r (specific resistance)p. p s p p pq ~ k k (solid compressive pressure)p. l p s l α r l log-log l v p ˆ. v p r n l p ep am n p l. p p ~ k k p e l Bm βp p p. Tillerm Shirato ˆk r p p ~ k k (p s, solid compressive pressure)p m(µ)p mp, e (7) (8)p np 1p n k p p p r p o vr n v m [10, 11]. p n r p pp p p p o n e(tiller[10], Shirato [11])p lk. Yim [12]p ˆk r p p ~ k k p mp k ~ w pq p p l ~ k k (solid compressive pressure of the first solid layer, p f ) p r r~ k ol l p e p rne. pl ep p k [12]l Š m. 2-3. h} m j h} m k p CPC e l p p p vp ˆ tp p (7)ep np rp. k p ˆ n, p k l p r vr v k. 1950 m 1960 l t n p 0.5 p p p p l m. Tillerm Horng[13]p 1983 np l k p r e, p e 2002 l Tillerm Li[14]l p k r l. rl k p compressibility m p, p l compactibility mp, p Table 1l ˆ l. Table 1l ˆ m p, np 0p p pq p vp k p l r p k l p o44 o5 2006 10k (7) (8) Table 1. Classification of cake compactibility n n = 0 n 0.4 ~ 0.7 n 0.7 ~ 0.8 n >1 Description Incompressible Moderately compactible Highly compactible Super compactible r. p mr ~ pqp l l ˆ, l k p lt (6)el p l p p l v. Tiller p l e l t n rp k v carbonyl ironp p. p vp k n p 0.005 r l [13]. np 0.4l 0.7p o v t r p k v kaolin flat D pp, np 0.4p [14]. np 1 k v d v pp, n p 1.4 r p [14]. kl n n k p n vp np 1 p p p k vp. np 1 p p l r p k p v eˆ v l p k l l v v k p p p ˆ. p p nk, k p l k p v e p l l e p wkv v, l v vp p., k p k p v e l p p p p. 2-4. k h} m m i m ~(dense skin) kl l m p n k p p l p l l k p v e l vv k. p l p t l ~m r p p p kt kp p l p q p q eˆv k (dense skin)p l p p. p l r~ k p 95~99Í p lv, p l o t k p p l l p p [3]. Tiller vp k vl p l p l, p p rp mp e p pv ll. Yim Ben-Aim[15]p k p p pv p l e p, p 10l p kp p l p r l, p sql e rp p p. v, ˆk p p p p 80Í v p p v k, p 0.97 p p v ˆ, l ~m r p p p 0.6 r p p p lr e rp ll. 3. m s 3-1. i m l n Fig. 2m p l k p rq m. p n l ˆkp op, k p l l eq m. k p p o d l n pl n, pq r }o. p n m l n p l pq r }o. k p pq r lp n l. l v, l n l l ~

Fig. 2. Schematic diagram of pressure filtration apparatus and gas saturation. lk p pq r l l. p n q o p po p k p ~ l ˆkl l l l m p o pl. er p q l ˆkp l l ˆkl l pq p, p p l pq r l -Œ e l on n l. 3-2. l m d tp o d m, d l jar-testerp ˆk v e l l d tp m. p dp n p o l e l p q m. dp tp p sr o e p t l o m. pvp s, p d v k e l e. 3-3. i z, mso l ~ Advantec ³ À ²É (p )l rs Advantec Toyo 5Am dp Sartorius l rs v 5 µm l p n m. pv p bentonite pq ˆkp rs pv l n m. p Š p volclay American Colloid Company r p, ˆkp coulter counter r, 19.3 µm p 33.4Í, 12.1 µm p 52.9Í, 7.63 µm p 72.3Í, 4.81 µm p 85.3Í ˆ. pvr (t)pk l rs kpm q pvr YCX- 452m kpm pvr Cyanamid Superfolc(Superfloc) C 581p n m. pvr YCX-452p q p 6 10 6 ~9 10 g/mol ~ 6 plp, pvr SC-581p q p 10 5 ~10 g/mol k (³ )pl 6. 2 L pƒl pqr p kpm q pvr kj l p pvr YCX-452p 0.1Í p nkp rs m. mr p l p l k 4 o C q l e l n m. p ˆ ( ) dl p p l p 471 4. y 4-1. mš m i 4-1-1. d n l m n v kp l p Š p 4 gp 500 ml pqr l l 30 k 250 rpm p l ˆkp rs m. p ˆkl 1Í kpm q pvr(sc-581) 10 ml ~ l, 4 10 m l p e. m p e m e p r. p p 7 reˆ r p 190~200 ml l. p r p l l l eq m. d eˆ l kl l p d tp l kl eˆ l e p m. Fig. 3l d tp v kkp m d e p, l k 1 kl p e ˆ l. Fig. 3p d tp v kp r rp l e p, p l kl d eˆ l e p p. d tp v k kp p n 25.9 s/cm 2pl, d lp p l n p tp v kkp p n p k p 11 s/cm 2 pl. p p (6)el p l l r, α av, d v kp rp l e p r p 6.56 10 11 m/kgpl, d e l e r p 2.72 10 11 m/kgpl. d e p p l r p k 1/2.4 (58.5Í ) m. p p rp r p vr l r l ~ e l l r p, rp l eˆ p p p. 4-1-2. d k l l e d k l l p kk o l, d eˆ p k p 0.5l 3 k v eˆ 1 kl l e Fig. 4l ˆ l. e s p Fig. 3l m p, v, d eˆ p k p eˆ p. Fig. 4l p 0.5 kl d eˆ 1 kl l p, p 1 kl Fig. 3. Filtration results of bentonite floc with and without at 1 atmu Korean Chem. Eng. Res., Vol. 44, No. 5, October, 2006

472 p Ë l Fig. 4. Filtration experimental result of bentonite floc with gas saturation pressure. Fig. 5. Filtration of 1 wt calcium carbonate suspension at 1 atm. Table 2. The values of the slopes and α av during filtration with various gas saturation pressures 0.5 atm 1 atm 2 atm 3 atm SlopeG[s/cm 2 ] 11.9 11.0 10.2 15.2 α av [m/kg] 3.02 10 11 2.79 10 11 2.58 10 11 3.85 10 11 d eˆ 1 kl l p. k p p pp, 2 p k pl l v v kk. l kp e 3 kl p d 1 kl p l, l (lk k 30 cm )p l 3 1 kl k 2 r ˆ p, p l l r vp p. p qp l p k p d p p l p, k p e p v m p p l k p v r( p lr) qkv, l v p Ž. p Table 2l r p v ˆ. q p o Table 2l op e l llv n l r p ˆ l. p p Š p p p k p 1 kl l e p p, l rl d k l l r p p ˆ p p. k p 0.5 kl 4 v e p p 2 kl l r p k 15Í r p m. l p k p 3 kl m r p v m. pl p d eˆ rr k p sq p p. 4-2. hm i k p rp vp ˆ dp 1 wtí ˆkl 1 kl l e p m. ˆ d ˆk 20, d eˆ l k 3 ˆkl eˆ l e p m. l k p 1 kp, d 1 kl e. Fig. 5l d tp v kk p m d e p p ˆ l. o44 o5 2006 10k Fig. 5l d tp lp l e p p, p 1wtÍ ˆ d ˆkp d 1 kl eˆ l e p p. d eˆv kkp np n 11.6 s/cm 2, d eˆ np n 9.50 s/cm 2pl. p p (6)el pe l r α av 1.16 10 12 m/kg m 9.50 10 11 m/kgp, d e p nl d n v kkp 11Í m. p Š p p n dl p r p 58.5Í l p v kp p. 4-3rl pl p r p p e. Fig. 5p t l rj p 100 ml e p k p, e p p m. 4-3. h} h} m m z i i m n m y kl k p p rp vp Š p k p p rp vp ˆ d ˆkl d n l e re m. rl Tiller[10] re l l l p e[12]p rn l, p p p. r, Š p ˆkp kpm q pvr pveˆ r p l l p l, CPC n l e p p ep a, n, B, β Table 3l ˆ l. p p p np v, k p 1.125p, p p Table 1p rpl p super compactible q k p p p. Table 3. The values of a, n, B, β of bentonite floc cake flocculated with anionic flocculant Values a 2.87 10 7 n 1.125 B 4.09 10 3 β 0.317

Fig. 6. Porosity distribution of the compressible cake formed with bentonite floc. Fig. 7. Liquid pressure distribution of the compressible cake formed with bentonite floc. Table 3l tlv p n rk k p l p l p l m kk Fig. 6 7l ˆ l. Fig. 6 7l x p x/l 0p p l ~m r p p p p, x/l 1p p ˆk r p p p p. rl p pp pp, Fig. 6l ˆk p (x/l=1)p p p 70Í v p v k, p 0.98 p p r p l. l ~m r p p (x/l=0) l r l p p k p. r lp p p qp p Tillerm Green[3]p dense skinp ( ) m. n p p (Ã Ã)p p vp. p sq om p l p 1973 p rp m lp [3], 1984 Yim[4]l p e rp sq p l. pm p l ~ l p p Fig. 7p k~ k l r. p k p n p l r~ p p l k p v k, l ~m r p p p l r~ p p 7Í p p l r~ k p 93.5Í. Š p p l l d e l p ˆ ( ) dl p p l p 473 v p p l p k m l vl. v, k~l p d v k~ p, 90Íp v k p p lp k~l kp ˆ ov. l l Fig. 7 l m p k p kv dp n. kp d l ( )p l ~ ˆ l pr v l errp qp p. p p p p, p p l l v qrrp r m. e t l ~ k l np m p p. pp, ˆ d pq p l l p l m kk m. Š p p m v ep p a, n, B, β p n. p p Tiller [16]p re p n, B, β p n l l p e[12]l p l a p n m. p p Table 4l ˆ l. Table 1l p moderatedly compactigle p p k n p 0.4~0.7p, p vp k p 0.192 k p p l p. Table 4l ˆ ep p n l ˆ d pq p l p m k~ k Fig. 8 9l ˆ l. k p qp p p l p Fig. 8p Fig. 6p k p n p p m. v, ˆ d p l ˆk r p (l ~m r p p k )l p p, l p p v k. p p Fig. 6p k p n p p m p. l ~m r p (x/l = 0)p tp, p Table 4. The values of a, n, b, β of CaCo 3 cake Values a 1.55 10 10 n 0.192 B 0.138 β 0.057 Fig. 8. Porosity distribution of the CaCO 3 cake. Korean Chem. Eng. Res., Vol. 44, No. 5, October, 2006

474 p Ë l Fig. 9. Liquid Pressure distribution of the CaCO 3 cake. Fig. 10. Filtration result of flocculated digestion sludge with and without at 0.5 atm. p 50Í p p p lp p p p v. k p qp ˆ d l p p kk Fig. 9l ˆ l. mr k p l kkp v p lk. Fig. 9l p kkp v p k n k p p p kk p Fig. 7 n ˆ p. k p l p x/ll p k v ˆ k p d ~ p. p ~ v qp p plr p p p l v p. p qp p l sq m p p p p p. n r l r p p v p p. k rl r m p ~ n v kp l r 1.16 10 m/kgl ~ 12 n n 9.50 10 m/kg p p p 11 p k llt. 4-4. s i d vp l r p k 10 13 ~10 14 m/kg op. d v vr l, l n rrp l r v k. l l r d v 800 mll 0.1Í kpm q pvr(ycx-452) ~ l 4 p 10 p m p pvp v, 7 re r t 200 ml } l l e p m. d tp l l l e Fig. 10l ˆ l. e l n l ~ Toyo 5Ap, l k p 0.5 kp. Fig. 10p l r v p n (6)el p l l r p, d tpeˆv kkp 6.72 10 11 m/kg pl, d eˆ l e 8.12 10 11 m/kg pl. d p d vp l r p k 20Í v m. p kp Š p p l m pl p p vp p. ~w pveˆ d v k p n v kk p v kk r p. pv d vl q rp e p ep CPC o44 o5 2006 10k r v l a, n, B, β p k l. ~rp k np p 0.7p p e. np 0.7 r p v kk ~ p lp, t l s j ~ np p p l l r p v eˆ p p. p nl rr pvrm pvs p n l p r k p p eˆ p kp Š p r p l eˆ p p p. w pveˆ d vp k p ƒ p n p. p d vl sq r p o vp l l pl ~ np p p p p. p n le ~ np p l l r p v eˆ. p nl p lp l ~ n p p p s, v, d vp s p s l o vp eˆ k p l ~ p p p sq p p. 5. p n k p p k p v p p r p v eˆ. l, p r r~ l r p v e k p v l v. p p p l v eˆ o, k p v p p k p r Š p p l e rk p ˆ d ˆkl d tpl l l e p m. r Š p l d e l n l 2 p v, ˆ d pq p l dp l p l p p lv m. p p (dense skin)p p n l p rp m. y 1. Tiller, F. M., The Role of Porosity in Filtration: Numerical

p ˆ ( ) dl p p l p 475 Methods for Constant Rate and Constant Pressure Filtration Based on Kozeny s Law, Chemical Engineering Progress, 49(9), 467-497(1953). 2. Tiller, F. M. and Cooper, H., The Role of Porosity in Filtration: V. Porosity Variation in Filter Cakes, AIChE. J., 8(4), 445-449 (1962). 3. Tiller, F. M. and Green, T. C., The Rold of Porosity in Filtration: IX. Skin Effect with Highly Compressible Materials, AIChE. J., 19(6), 1266-1269(1973). 4. Yim, S. S., Filtration Sur Gateau Compressible, Ph. D. Dissertation, L'Institut National Polytechnique de Toulouse, France(1984). 5. Carman, P. C., Fundamental Principles of Industrial Filtration, Transactions - Institution of Chemical Engineers, 168-188(1938). 6. D Arcy, H. P. G., Les Fontaines Publiques de la Ville de Dijon, Victor Dalmont, Paris(1856). 7. Yim, S. S., A Theoretical and Experimental Study on Cake Filtration With Sedimentation, Korean J. Chem. Eng., 16(3), 308-315 (1999). 8. Yim, S. S., Kwon, Y. D. and Kim, H. I., Effects of Pore Size, Suspension Concentration, and Pre-sedimentation on the Measurement of Filter Medium Resistance in Cake Filtration, Korean J. Chem. Eng., 18(5), 741-749(2001). 9. Yim, S. S., Song, Y. M. and Jun, S. J., Study on the Measurement of Average Specific Cake Resistance in Cake Filtration of Particulate Suspension and Sedimented Floc, HWAHAK KONG- HAK, 40(3), 330-339(2002). 10. Tiller, F. M., The Role of Porosity in Filtration II: Analytical Equations for Constant Rate Filtration, Chem. Eng. Prog., 51(6), 282-290(1955). 11. Shirato, M., Kato, H., Kobayashi, K. and Sakazaki, H., Analysis of Settling of Thick Slurries due to Consolidation, J. Chem. Eng. Japan, 3(1), 98-104(1970). 12. Yim, S. S., Song, Y. M. and Kwon, Y. D., The Role of P i, P a, and P f in Constitutive Equation, and Boundary Condition in Cake Filtration, Korean J. Chem. Eng., 20(2), 334-342(2003). 13. Tiller, F. M. and Horng, L. L., Hydraulic Deliquoring of Compressible Filter Cakes, AIChE J., 29(2), 297-305(1983). 14. Tiller, F. M. and Li, W., Theory and Practice of Solid/Liquid Separation, 4th ed., Frank M. Tiller and Wenping Li(2002). 15. Yim, S. S. and Ben-Aim, R., Highly Compressible Cake Filtration: Application to the Filtration of Flocculated Particles, 4 th World Filtration Congress, A1-A7(1986). 16. Tiller, F. M., Crump, J. R. and Ville, F., Filtration Theory in its Historical Perspective, A Revised Approach with Surprises, 2 nd World Filtration Congress, 1-13(1979). Korean Chem. Eng. Res., Vol. 44, No. 5, October, 2006