Ind. Eng. Chem. Res. 1998, 37, 609-614
609
Modeling and Simulation of a Packed Column for NOx Absorption with Hydrogen Peroxide J. L. de Paiva* and G. C. Kachan Department of Chemical Engineering, University of Sa˜ o Paulo, Av. Lineu Prestes, 580, Cidade Universita´ riasButanta˜ , CEP 05424-970 Sa˜ o Paulo, Brazil
The absorption of dilute NOx gas was studied, at atmospheric pressure, in an industrial column packed with 25-mm plastic Pall rings. The scrubbing liquid was a dilute hydrogen peroxide solution. NOx removal efficiencies of 75-91% were obtained for gas mixtures with partial pressures of NOx in the range of 62.8-460 N/m2. A model was developed on the basis of equilibrium, chemical reactions, mass transfer in gas and liquid phases, and consideration of HNO2 and NO oxidation by H2O2 in the liquid phase. The removal efficiencies calculated using this model fairly agreed with the experimental data. The HNO2 formation in the gas phase largely determines the NOx absorption rate. Its oxidation by H2O2 improves the NOx removal. The influences of various parameters in the NOx removal efficiency are discussed from numerical simulations. Introduction The removal of NOx from industrial gas streams is important due to stringent environmental restrictions regarding pollutant emissions. The NOx absorption is a complex matter which generated a significant amount of publications and several reviews by Sherwood et al. (1975) and Joshi et al. (1985). In order to model the NOx absorption in laboratoryscale equipment and in absorption towers, it is required to combine equilibrium, chemical reactions, and mass transfer in gas and liquid phases. Representative models were developed and studied by Andrew and Hanson (1961), Hofytizer and Kwanten (1972), Counce (1980), Counce and Perona (1979, 1983, 1986), Carta (1984), Joshi et al. (1985), Selby and Counce (1988), Newman and Carta (1988), Suchak et al. (1991), Jethani et al. (1992), and Suchak and Joshi (1994). There is too few experimental data and information available in the literature regarding an industrial column for NOx absorption. The main objective in the present work is to study the removal of NOx from a nitrocellulose plant by chemical absorption with dilute hydrogen peroxide solutions in an industrial packed tower. In the model developed the contribution of HNO2 formation in the gas phase was considered in the absorption of dilute NOx. Different scrub liquors have been proposed for the scrubbing of NOx tail gas. In spite of the high cost of hydrogen peroxide the scrubbing process showed to be viable to enhance the performance of a previously installed absorption system. Minor modifications in the original system were necessary, and the waste liquor, dilute nitric acid, was recycled to the process. Experimental data were obtained in an industrial column and were compared with the model prediction. The Mathematical Model The packed column has been modeled for the absorption of dilute NOx in dilute hydrogen peroxide solutions, considering the following assumptions: 1. Gas and liquid phases flow countercurrent with recycle of dilute scrub solution.
2. Plug flow of the gas and liquid phases. 3. Isothermal condition, considering the high dilution of both phases. 4. Negligible pressure drop in the packing. 5. Steady-state operation. Gas and Liquid Phases Model The chemical species assumed in the gas phase are NO, NO2, N2O3, N2O4, HNO2, H2O, O2, and N2. The gas phase is assumed to be ideal and saturated with H2O. Since the partial pressure of H2O2 is usually small over dilute aqueous solutions at ambient temperature, it was considered to be zero. The following reactions are assumed in the gas phase:
2NO + O2 f 2NO2
(1)
2NO2 T N2O4
(2)
NO + NO2 T N2O3
(3)
NO + NO2 + H2O T 2HNO2
(4)
The oxidation of NO (1) is an irreversible third-order reaction and its rate decreases as temperature is increased (Joshi et al., 1985). The reactions 2-4 are considered at equilibrium and the equilibrium constants are presented in Table 1. The partial pressures of superior (NO2*) and inferior (NO*) nitrogen oxides are generally defined as the following (Andrew and Hanson, 1961):
1 PNO2* ) PNO2 + 2PN2O4 + PN2O3 + PHNO2 2
(5)
1 PNO* ) PNO + PN2O3 + PHNO2 2
(6)
and for the effective partial pressure of NOx:
PNOx ) PNO* + PNO2*
S0888-5885(96)00301-6 CCC: $15.00 © 1998 American Chemical Society Published on Web 01/06/1998
(7)
610 Ind. Eng. Chem. Res., Vol. 37, No. 2, 1998
The following reactions are assumed in the liquid phase:
Table 1. Gas Phase Reactions reactions (1)
rate and equilibrium constants
k1 ) 1.79 × 10
-11
refs
1501 exp T
(
)
Bodenstein (1918)
Hoftyzer and Kwanten (1972)
(2)
K2 ) 6.98 × 10-15 exp
(6866 T )
(3)
K3 ) 4.12 × 10-13 exp
4869 T
Newman and Carta (1988)
(4)
K4 ) 1.825 × 10-12 exp
(4723 T )
Hoftyzer and Kwanten (1972)
(
)
The parameter to express the gases composition is the oxidation degree, ξ, defined as (Hoftyzer and Kwanten, 1972):
ξ ) PNO2*/PNOx
(8)
Assuming equilibrium throughout the bulk gas phase, the nitrogen oxides partial pressures may be expressed as
PN2O4 ) K2PNO22
(9)
PN2O3 ) K3PNO2PNO
(10)
PHNO22 ) K4PNO2PNOPH2O
(11)
Equations 9-11 are substituted in (5) and (6) and then in (7) obtaining (12):
PNOx ) (PNO2 + 2K2PNO22 - PE)(1 + 2K3PNO2) + 2
1/2
(PNO2 + 2K2PNO2 - PE) (K4PH2OPNO2)
1/2
+ PNO2 +
2K2PNO22 (12)
2NO2 (l) + H2O(l) f HNO2 (l) + HNO3 (l)
(16)
N2O4 (l) + H2O(l) f HNO2 (l) + HNO3 (l)
(17)
N2O3 (l) + H2O(l) f 2HNO2 (l)
(18)
In the case of dilute aqueous solutions reaction 16 is considered slow, irreversible and of pseudo second order (Lee and Schwartz, 1981) and reactions 17 and 18 are considered fast, irreversible, and of pseudo first order. The presence of H2O2 in the liquid phase improves the NOx absorption by destroying HNO2 and NO in the liquid due to their corresponding oxidation (Carta, 1984). In this case the following reactions are considered:
2NO(l) + 3H2O2 (l) f 2HNO3 (l) + 2H2O(l)
(19)
HNO2 (l) + H2O2 (l) f 2HNO3 (l) + H2O(l)
(20)
The oxidation of NO by H2O2 is considered fast and irreversible. The reaction is of first order concerning the NO and H2O2 (Baveja et al., 1979). The oxidation of HNO2 is considered fast and irreversible. The orders concerning HNO2 and H2O2 are 4/3 and 2/3, respectively (Karlsson, 1983). For the condition observed in this work, the N2O4, N2O3, and NO2 hydrolysis and NO oxidation are considered fast, whereas HNO2 oxidation is considered slow. In this case the rates of mass transfer with chemical reaction in the liquid are
RL,N2O4 ) xDN2O4k17HN2O4PN2O4i
(21)
RL,N2O3 ) xDN2O3k18HN2O3PN2O3i
(22)
RL,NO2 ) x2DNO2k16/3(HNO2PNO2i)3/2
(23)
RL,NO )
and defining (Counce and Perona (1983))
PE ) PNO2* - PNO* ) PNO2 + 2K2PNO22 - PNO ) (2ξ - 1)PNOx (13)
xD
NOk19CH2O2
HNOPNOi
b
RL,HNO2 ) kL,HNO2HHNO2PHNO2i
(24) (25)
Mass Balance in the Interface
The heterogeneous system can be characterized by the following variables: pressure, temperature, HNO3 concentration in liquid phase, NOx partial pressure (PNOx), and oxidation degree (ξ), which in turn allows one to calculate PNOx, PE, PH2O, K2, K3, and K4. The compositions PNO, PNO2, PN2O3, PN2O4, and PHNO2 are availed from (9)-(11). The rates of gas phase mass transfer of species j are expressed according to film theory by
The rate of mass transfer of NO2* and NO* through the gas film is given by
RG,j ) kG,j(Pjb - Pji)
and the rate of mass transfer of NO2* and NO* through the liquid phase by
(14)
In spite of reactions 1-4 in the gas film their effects in the diffusive flux is not considered by simplification (Newman and Carta, 1988). Assuming equilibrium at the gas-liquid interface, Henry’s law applies:
Cji ) HjPji
(15)
1 RG,NO2* ) RG,NO2 + 2RG,N2O4 + RG,N2O3 + RG,HNO2 2 (26) 1 RG,NO* ) RG,NO + RG,N2O3 + RG,HNO2 2
(27)
1 RL,NO2* ) RL,NO2 + 2RL,N2O4 + RL,N2O3 + RL,HNO2 (28) 2 1 RL,NO* ) RL,NO + RL,N2O3 + RL,HNO2 2 The NO2* and NO* balances at the interface give
(29)
Ind. Eng. Chem. Res., Vol. 37, No. 2, 1998 611
1 RG,NO2 + 2RG,N2O4 + RG,N2O3 + RG,HNO2 ) RL,NO2 + 2 1 2RL,N2O4 + RL,N2O3 + RL,HNO2 (30) 2 1 RG,NO + RG,N2O3 + RG,HNO2 ) RL,NO + RL,N2O3 + 2 1 R (31) 2 L,HNO2 At the interface the equilibrium compositions are assumed according to (2)-(4) and are expressed by the following equations:
PN2O4i ) K2(PNO2i)2
(32)
PN2O3i ) K3PNO2iPNOi
(33)
PHNO2i ) (K4PNO2iPNOiPH2Oi)1/2
(34)
The following two equations are obtained in terms of PNOi and PNO2i by substituting (9)-(11), (32)-(34), (14), and (21)-(25) into (30) and (31):
A1 +
A2PNOi
+
i
A3PNO2 PNOi
i
i 3/2
B1 + B2PNO2 + B3(PNO2 ) i
B5PNO2 PNOi
+
i
A4(PNO2 PNOi)1/2
)0 (35)
i 2
+ B4(PNO2 ) +
+ B6(PNO2iPNOi)1/2 ) 0 (36)
Figure 1. Schematic diagram of the industrial column.
finds that the mass balance across a differential height dz results in the following equation (Levenspiel, 1972):
dPj SRT ) (-RG,ja + Vrj) dz Gv
The velocity reaction r1 accounts for the gas phase oxidation of NO to NO2 and is expressed by (38). The concentration of O2 was assumed constant over the column.
r1 )
where
1 A1 ) kG,NOPNOb + kG,N2O3PN2O3b + kG,HNO2PHNO2b 2
x
A2 ) -kG,NO - HNO k19DNOCH2O2b A3 ) -K3(kG,N2O3 + HN2O3xDN2O3k18) A4 ) -
1 K4PH2Ob(kG,HNO2 + kL,HNO2HHNO2PHNO2b) 2
x
B1 ) kG,NO2PNO2b + 2kG,N2O4PN2O4b + kG,N2O3PN2O3b + 1 b P k 2 G,HNO2 HNO2 B2 ) -kG,NO2
x
B3 ) - 2k16DNO2HHNO23/3 B4 ) -2K2(kG,N2O4 + HN2O4xDN2O4k17) B5 ) -K3(kG,N2O3 + HN2O3xDN2O3k18) B6 ) -
1 K4PH2Ob(kG,HNO2 + kL,HNO2HHNO2PHNO2b) 2
x
Mass Balance in the Packed Tower Assuming constant total molar flow rate due to the dilution of the gas phase and constant pressure, one
(37)
k1 P 2P RT NO O2
(38)
Further reactions are already considered in the assumption of equilibrium. Experimental Apparatus and Procedure Experimental data were collected from an industrial column of a nitrocellulose plant in Brazil. The schematic diagram of the industrial column is shown in Figure 1 (inside diameter of 3 m, 25 mm plastic Pall rings packing in a bed of 6.4 m height). A mixture of air and NOx was scrubbed with dilute HNO3 and hydrogen peroxide solutions. The scrubbing liquid was pumped to the top of the packing at a flow rate of 5.55 × 10-2 m3/s and collected at the bottom in a small tank. The liquid overflow consisted of dilute nitric acid and hydrogen peroxide solution. The remaining solution was recycled to the column with further make up of water and hydrogen peroxide. Considering the high recycle ratio, the concentrations of nitric acid and hydrogen peroxide were taken as constant throughout the column. The gas stream containing NOx was fed in the bottom of the column and the volumetric flow rate was measured using a Pitot tube. Both liquid and gas streams were manually sampled. The feed and effluent gaseous NOx (NO* + NO2*) contents were determined on the basis of the EPA (1977) method. The NO2* to NOx ratio (degree of oxidation ξ) of the feed was determined by absorption/reaction with potassium permanganate and back titration with sodium tiossulfate, as suggested by Peters and Holman (1955), and by the total NOx content. In the liquid phase the total acidity (HNO3 + HNO2)
612 Ind. Eng. Chem. Res., Vol. 37, No. 2, 1998 Table 2. Experimental Conditions scrubbing liquid
gas velocity (kg/(m2 s)) liquid velocity (kg/(m2 s)) mean temperature of the column (K) mean pressure (kPa) mean degree of oxidation partial pressure of NOx in feed (Pa) NOx conversion HNO3 concentration in the scrubbing liquid (kmol/m3) H2O2 concentration in the scrubbing liquid (kmol/m3)
presence of H2O2
absence of H2O2
0.295 8.24 301-310 98.5 0.64 62.8-460 0.75-0.91 0.34-1.47
0.295 8.24 300-305 98.5 0.64 96.6-395 0.44-0.71 0.7-1.38
0.29-2.4
0
Figure 3. Experimental- and model-predicted conversion of NOx vs the feed partial pressure of NOx for absorption in the presence of H2O2. Conditions assumed for model predictions: ξ ) 0.64; T ) 303 K; L ) 8.24 kg m-2 s-1; G ) 0.295 kg m-2 s-1; CH2O2 ) 1.4 kmol/m3.
Figure 2. Experimental conversion of NOx vs the feed partial pressure of NOx for absorption in the presence and absence of H2O2.
was determined by neutralization with sodium hydroxide. The hydrogen peroxide concentration was determined by permanganimetri. The temperatures at the gas and liquid phases were also measured. The experimental data were collected in two different conditions: NOx scrubbing with dilute nitric acid and with dilute nitric acid and hydrogen peroxide solutions. The NOx content of the gas feed was not constant, but only the data in steady-state condition were considered. The experimental conditions are presented in Table 2. Numerical Simulations and Experimental Results The conversion vs the feed partial pressure of NOx observed experimentally is plotted in Figure 2 for the cases of absorption in the presence and absence of hydrogen peroxide in the liquid phase. There is an increase of removal efficiency in the presence of hydrogen peroxide in the liquid phase. The solution procedure of the mathematical model is based on Counce and Perona (1983) and on Suchak et al. (1991). Equation 37 is discretized according to Euler’s method. Knowing the partial pressures of the gases entering the height increment allows the calculation of the interfacial partial pressures PNOi and PNO2i from (35) and (36) and the gas and liquid rates of mass transfer.
In this way the partial pressures of components leaving the increment are obtained from the mass balance (37). Further corrections of partial pressures in the bulk gases are made assuming equilibrium conditions expressed by (9)-(11). The values of k1, K2, K3, and K4 were obtained from the references in Table 1. The value of k19 given by Baveja (1979) was used here. The parameter [H(Dk17)1/2]N2O4 used in the calculations was obtained from Hoftyzer and Kwanten (1972). The parameter [H(Dk18)1/2]N2O3 used was obtained from Corriveau et al., as recommended by Counce and Perona (1983) and Joshi et al. (1985), and was assumed to have the same behavior of the parameter [H(Dk17)1/2]N2O4 with temperature. Henry’s law constant for NO as recommended by Pirkl (1992) was used here. Henry’s law constant for HNO2 used was recommended by Counce (1980) and its behavior with temperature was assumed like N2O4. The value of k16 and HNO2 were obtained from the work of Lee and Schwartz (1981) at 22 °C and was assumed behavior of these parameters with temperatures like those of k17 and HN2O4. The values of kG, kL, and a were calculated from the correlations of Onda et al. (1968), Mohunta et al. (1969) and Puranik and Vogelpohl (1974), respectively, as recommended by Charpentier (1981). As shown in Table 2 there are some variations in experimental conditions; the conditions assumed for model predictions were (1) degree of oxidation, 0.64; (2) temperature, 303 K; (3) hydrogen peroxide concentration, if present, 1.4 kmol/m3; (4) gas velocity, 0.295 kg/ (m2 s); (5) liquid velocity, 8.24 kg/(m2 s). Figure 3 presents experimental data and the model predicted that seems fairly good. The importance of nitrous acid formed in the NOx absorption may be seen comparing the model prediction and a hypothetical situation in which is assumed PHNO2 ) 0. To understand the influence of various parameters, some numerical simulations were performed referring to a column of 3 m internal diameter packed with 25 mm plastic Pall rings at 101 kN/m2 with recycle of a dilute hydrogen peroxide solution.
Ind. Eng. Chem. Res., Vol. 37, No. 2, 1998 613
Figure 4. Effect of gas velocity on NOx removal: L ) 6 kg m-2 s-1; T ) 298 K; PNO* ) 100 Nm-2; PNO2* ) 150 Nm-2; CH2O2 ) 1.4 kmol m-3.
Figure 6. Effect of degree of oxidation on NOx removal: L ) 6 kg m-2 s-1; T ) 298 K; G ) 0.4 kg m-2 s-1; PNOx ) 250 Nm-2; CH2O2 ) 1.4 kmol m-3.
Conclusions
Figure 5. Effect of liquid velocity on NOx removal: G ) 0.4 kg m-2 s-1; T ) 298 K; PNO* ) 100 Nm-2; PNO2* ) 150 Nm-2; CH2O2 ) 1.4 kmol m-3.
A simplified mathematical model combining equilibrium, chemical reactions, and mass transfer in gas and liquid phases has been developed for the absorption of nitrous gases (NOx) in a packed column with dilute hydrogen peroxide solutions. The model presented here should be useful for conservatively estimating scrubber efficiency of dilute NOx gas absorption in dilute hydrogen peroxide solution. It was shown that the NOx absorption is primarily affected by the oxidation degree, which determines the equilibrium gas composition and consequently the HNO2 formation, the major transporting species for the absorption of NOx in this case. The NOx removal is also influenced by others parameters such as gas and liquid flow rates. The presence of H2O2 in the liquid phase represents a good method to improve NOx removal. It eliminates the HNO2 decomposition and thus the NO desorption which has a deleterious effect in NOx removal efficiency. Nomenclature
The simulation results are expressed as the NOx partial pressure along column height for different parameters conditions. The feed gas is air containing NOx at a inlet concentration of 250 N/m2 (ca. 2500 ppm in volume). Figure 4 shows that the absorption efficiency decreases with the increase in the gas velocity. The effect of liquid velocity is shown in Figure 5. Initially NOx absorption is fast due to HNO2 formation; this is explained by the increase of the magnitude of parameters a, kG, and kL. However, for a height greater than 2.5 m, the NOx concentrations decrease very slightly, being quite independent of the liquid flow rate; the NOx is mainly in the form of NO2/N2O4 whose absorption rate is low. Figure 6 shows that the variations in the degree of oxidation cause a pronounced effect on the absorption rate. This behavior is associated mainly with the formation of HNO2, which is very soluble. The role of nitrous acid formed in the NOx absorption is shown in Figure 6. The dotted curves correspond to the hypothetical situation in which PHNO2 ) 0 for different degrees of oxidation.
a ) gas-liquid interfacial area, m-1 A1, ..., A4 ) parameters of eq 35 B1, ..., B6 ) parameters of eq 36 Cj ) concentration of component j, g mol/m3 Dj ) diffusion coefficient of component j, m2/s Gv ) gas flow rate, m3/s G ) gas velocity, kg/(m2 s) Hj ) Henry’s law constant of component j, g mol/(m3 N/m2) in ) in kG,j ) gas mass-transfer coefficient of component j, g mol/ (m2 s N/m2) kL,j ) liquid mass-transfer coefficient of component j, m/s k1 ) rate constant for reaction 1, (N/m2)-2 n k16 ) rate constant for reaction 16 k17 ) rate constant for reaction 17 k18 ) rate constant for reaction 18 k19 ) rate constant for reaction 19 K2 ) equilibrium constant for reaction 2, (N/m2)-1 K3 ) equilibrium constant for reaction 3, (N/m2)-1 K4 ) equilibrium constant for reaction 4, (N/m2)-1 L ) liquid velocity, kg/(m2 s) NO* ) inferior nitrogen oxides (NO + N2O3 + HNO2/2)
614 Ind. Eng. Chem. Res., Vol. 37, No. 2, 1998 NO2* ) superior nitrogen oxides (NO2 + N2O3 + 2N2O4 + HNO2/2) NOx ) total nitrogen oxides (NO* + NO2*) out ) out P ) total pressure, N/m2 PE ) parameter defined by (13) Pjb ) partial pressure of component j in bulk of gas Pji ) partial pressure of component j at gas-liquid interface r1 ) rate of reaction expressed by eq 38, g mol/m3 RG,j ) rate of gas phase mass transfer of component j, g mol/(m2 s) RL,j ) rate of absorption of component j, g mol/(m2 s) R ) universal gas constant, (m3 N/m2)/(g mol K) S ) cross-sectional area of column, m2 T ) temperature, K XNOx ) NOx conversion; XNOx ) [(PNOx)in - (PNOx)out]/[(PNOx)in] z ) height of packed bed, m Greek Symbols ξ ) oxidation degree defined by (8) v ) column voidage fraction
Literature Cited Andrew, S. P. S.; Hanson, D. The Dynamics of Nitrous Gas Absorption. Chem. Eng. Sci. 1961, 14, 105. Baveja, K. K.; Rao, D. S.; Sarkar, M. K. Kinetics of Absorption of Nitric Oxide in Hydrogen Peroxide Solutions. J. Chem. Eng. Jpn. 1979, 12 (4), 322-325. Bodenstein, M. The Rate of the Reaction between Nitric Oxide and Oxygen. Zeit. Elektrochem. 1918, 34, 183. In Counce, R. M., 1980. Carta, G. Role of HNO2 in the Absorption of Nitrogen Oxides in Alkaline Solutions. Ind. Eng. Chem. Fundam. 1984, 23, 260. Charpentier, J. C. Advances in Chemical Engineering; Academic Press: New York, 1981; Vol. 11, pp 2-133. Corriveau, C. E. The Absorption of N2O3 into Water. Master’s Thesis, University of California, Berkeley, CA, 1971. In Sherwood, T. K.; Pigford, R. L.; Wilke, C. R. 1975. Counce, R. M. The Scrubbing of Gaseous Nitrogen Oxides in Packed Towers. Ph.D. Dissertation, The University of Tenessee, Knoxville, TN, 1980. Counce, R. M.; Perona, J. J. Gaseous nitrogen absorption in a sieve-plate column. Ind. Eng. Chem. Fundam. 1979, 18, 400. Counce, R. M.; Perona, J. J. Scrubbing of Gaseous Nitrogen Oxides in Packed Towers. AIChE J. 1983, 29, 26. Counce, R. M.; Perona, J. J. Designing Packed-Towers Wet Scrubbers: Emphasis on Nitrogen Oxides. In Handbook of Heat and Mass Transfer; Cheremisinoff, N. P., Ed.; Gulf Pub. Co.: Houston, TX, 1986; Vol. 21, p 953.
Hofytizer, P. J.; Kwanten, F. J. G. Absorption of Nitrous Gases. Process for Air Pollution Control;CRC Press: Cleveland, OH, 1972. Jethani, K. R.; Suchak,N. J.; Joshi, J. B. Modeling and Simulation of Spray Column for NOx Absorption. Comput. Chem. Eng. 1992, 16 (1), 11-25. Joshi, J. B.; Mahajani, V. V.; Juvekar, V. A. Invited review: Absorption of NOx Gases. Chem. Eng. Commun. 1985, 33, 1-92. Karlsson, H. T. Liquid Phase Oxidation of Nitrous Acid by Hydrogen Peroxide. Acta Chem. Scand. 1983, A37 (3), 241246. Lee, Y. N.; Schwartz, S. E. Reaction Kinetics of Nitrogen Dioxide with Liquid Water and Low Partial Pressure. J. Phys. Chem. 1981, 85 (7), 840-848. Levenspiel, O. Chemical Reaction Engineering, 2nd ed.; Wyley: New York, 1972. Method 7-Determination of Nitrogen Oxides Emissions from Stationary Sources; U.S. Environmental Protection Agency: Washington, DC, 1977; Vol. 42, no. 160. Mohunta, D. M.; Vaidyanathan, A. S.; Laddha, G. S. Indian Chem. Eng. 1969, 11 (3), 73. In Charpentier, J. C., 1981. Newman, B. L.; Carta, G. Mass Transfer in the Absorption of Nitrogen Oxides in Alkaline Solutions. AIChE J. 1988, 34 (7), 1190-1199. Onda, K.; Takeuchi, H.; Okumuto, Y. J. Chem. Eng. 1968, 1 (56). In Charpentier, J. C., 1981. Peters, M. S.; Holman, J. L. Vapor and Liquid-phase Reactions betwen Nitrogen Dioxide and Water. Ind. Eng. Chem. 1955, 47 (12), 2536-2539. Pirkl, H. G. Stoffaustausch und Reaktion bei der Absorption von Stickstoffdioxid und Schwefeldioxid aus Rauchgasen. DoktorIngenieur, Universita¨t Erlangen, Nu¨rnberg, Germany, 1992. Puranik, S. S.; Vogelpohl, A. Chem. Eng. Sci. 1974, 29, 501. In Charpentier, J. C., 1981. Selby, G. W.; Counce, R. M. Aqueous Scrubbing of Dilute Nitrogen Oxide Gas Mixtures. Ind. Eng. Chem. Res. 1988, 27, 1917-1922. Sherwood, T. K.; Pigford, R. L.; Wilke, C. R. Mass Transfer, 1st ed.; McGraw-Hill: New York, 1975. Suchak, N. J.; Joshi, J. B. Simulation and Otimization of NOx Absorption System in Nitric Acid Manufacture. AIChe J. 1994, 40 (6), 944-956. Suchak, N. J.; Jethani, K. R.; Joshi, J. B. Modeling and Simulation of NOx Absorption in Pilot-scale Packed Columns. AIChe J. 1991, 37 (3), 323-339.
Received for review May 31, 1996 Revised manuscript received October 21, 1997 Accepted October 30, 1997 IE960301A
