Air containing 1.6 vol% sulfur dioxide is scrubbed with pure water in a packed column of 1.5-m2 cross-sectional area and 3.5-m height packed with no. 2 plastic Super Intalox saddles, at a pressure of 1 atm. Total gas flow rate is 0.062 kmol/s, the liquid flow rate is 2.2 kmol/s, and the outlet gas SO2 concentration is y = 0.004. At the column temperature, the equilibrium relationship is given by y* = 40x.

(a) What is L/Lmin?

(b) Calculate NoG and compare your answer to that for the number of theoretical stages required.

(c) Determine HOG and the HETP from the operating data.

(d) Calculate KGa from the data, based on a partial-pressure driving force as in item 2 of Table6.7.

Table 6.7 Alternative Mass-Transfer Coefficient Groupings Height of a Transfer Unit, HTU Number of Transfer Units, NTU EM Diffusion or Dilute UM Diffusion EM Diffusion or Dilute UM Diffusion UM Diffusion UM Diffusion Symbol Symbol Driving Force dy (1 )Ldy (1 y)(y y*) 1. (y y*) NoG (y y*) aS (1 ) S ( )Ldp (P p)(p p*) dp NoG 2. (p p*) (p p*) (1 )L S KgaPS V' V' dY dY NoG 3. (Y Y*) G |Y - Y*) Kyas Kyas (Y Y*) dy (1 )Ldy (1 y)(y y) NG 4. ( ) kyas kj(1 )S - y) (y (P p)LMdp J P - p)(p Pi) dp 5. (p Pi) NG ( )LS kpa PS (p - (1 )Ldx dx HOL 6. (x* ) NOL (1 )LS aS (x* (1 x)(x* x) dc (PL/ML c)LMdx 7. (c* c) HOL NOL J(/M - )(* ) KLa(pL/ML)S K'a(pL/ML c)LMS L' L' dX dX NOL 8. (X* X) HOL as aS (X* - X) (X* X) (1 - x)LMdx (1 x)(x x) dx L NL 9. (x1 - x) kzaS ka(1 )LS ( \x) L. dc (PL/ML c)LMdc 10. ( ) N. . J (PL/ML - c)(c - c) kla(pL/ML)S kia(pL/M )LS (c c) "The substitution Ky = K,YBLM or its equivalent can be made.