absorption of no2 in a packed tower with na2so3 aqueous solution

Absorption of NO2 in a Packed Tower with Na~S03 Aqueous Solution Luke Chen? Jin-Wei Lin? and Chen-lu Yawb - a Tamkang University, Department of Water Resources and Environmental Engineering, Tamsui, Taipei Hsien, Taiwan

University of Massachusetts Dartmouth, Advanced Technology and Manufacturing Center, 151 Martine Street, Fall River, MA 02723

This paper looks at the development of a two-stage chemical scrubber for NO, control. In the first stage, the mostprac- tical oxidizing agents for NO oxidation are sodium chlorite and sodium hypochlorite. Although a considerable amount of work has been done on the reaction kinetics of NO2 with N a S O 3 there are majorgaps in developing an N a S O

particular importance is the rate of chemical absorption. A pilot-scale research program was initiated to evaluate the absorption rate of NO2 with Na#03 aqueous solution in a packed tower. The research is directed at obtaining height of a transfer unit (KTJ for NO2 absorption, and to determine reasonable operation conditions for the packed bed scrubber A sulfite concentration of 0.25 M is essential to have a reasonable HTU in 2 to 5 feet for a gas rate between 1,050 to 2,350 lb@ hr. The results indicate that the scrubbing effectiveness of NO2 increased with the L/G ratio, and an WG of more than 3 is required for high NO2 absorption.

aqueous solution for NO2 absorption in the second stage. d f

INTRODUCTION The Clean Air Act Amendment of 1930 provided a reg-

ulatory drive for reducing nitrogen oxides (NO,) from sta- tionary sources. The NO, in flue gases essentially consists of nitric oxide (NO) and nitrogen dioxide (NO$. NO2 can be effectively absorbed in some aqueous solutions, but not NO [l, 21. Unfomnately, most (more than 95%) of the NO, emitted in flue gases are NO. Therefore, in a two- stage chemical scrubbing system for NO, emission control, NO oxidation is a crucial first step. The slow oxidation rate of NO in air can be increased by injecting a strong oxidizing agent, such as ozone(O3) [21, chlorine dioxide (C102) [3,41, or chlorine (C12) [51 into the flue gas, or adding an oxidant, such as sodium chlorite (NaC102) 16-81, hydrogen peroxide (H202) DI, sodium hypochlorite (NaClO) I8, 101, or potassium permanganate (KMn0,Q [2, 101, to the scrubbing solution.

In recent years, some two-stage chemical scrubbing systems have reached either pilot-scale demonstration, or full-scale installation. Among them are a hypochlorite/sulfide system from Trih4er 1111 and from Environ- air 1121, ozone/sodium hydroxide (NaOH) system from BOC-Cannon [131, chlorite/sulfite I141 and pulsed

corona/sulfite systems from Beltran 115, 161, and pulsed corona/thiosulfate system from ADA I171.

CHEMISTRY OF NO2 ABSORPnON The effectiveness of sodium sulfite (Na2S03) aque-

ous solution for NO2 absorption was documented in the early 1970s [l, 21. Due to its limited applications, little effort was made to develop sulfite scrubbers for pollution control. However, research on the reaction rate and mechanisms of NO2 with sulfur(IV) was pur- sued to better understand the role of NO, in atmospheric droplets [18-201 and NO2 influence in a limestone flue gas desulfurization system I21-251. The products and stoichiometry upon bubbling NO2 through a HSO3- solution suggest that the overall reaction may be described by [181:

2 NO2 + S03-2 + H20 + 2 NO2- + 2 H+ + S04-2 (1)

Essentially no N O or NO3- appeared to be pro- duced. Clifton, et a l . [231 suggest that the reaction appears to involve the formation of an intermediate complex, which can undergo subsequent reaction with NO2 or others. In an atmospheric droplet, the fate of the intermediate might not simply react with other N 0 2 , since NO2 will be at such a low concentration. in a flue gas scrubber, particularly when the gas phase NO is converted to N02 , the intermediate is much more likely to react with additional NO2 due to its much higher concentrations. Littlejohn, et a l . [241 believes that the reaction initially produces a nitrite ion and a sulfite radical:

NO2 + S03-2 + N02- + SO3'-

The sulfite radical (SOg'-) can undergo either recombination or reaction with oxygen. Dithionate ion (S204-2) was observed as a product in all of the reaction mixtures from studies done without o gen. The

feasible mechanism for the production of dithionate is the recombination reaction of sulfite radicals:

ratio of the two main products (S04-2/S206 7 1 is 1.8. A

Environmental Progress (V01.21, No.4) December 2002 225

(3)

In the presence of oxygen, sulfite radicals were consumed by oxygen:

s0g'- + 0 2 + so5'- (4)

The reaction is very fast, approaching the diffusion control limit. At low sulfite radical concentrations and large dissolved oxygen concentrations, Reaction 3 is insignificant compared to Reaction 4. After a compli- cated mechanism, sulfate ion is the major end product in the solution.

Absorption of NO2 occurs with simultaneous mass transfer and fast chemical reaction. Although previous investigators have studied the reaction of NO2 with SO -2, those studies were performed under conditions

Rochelle 1251 measured NO2 absorption rate in sodium sulfite aqueous solution under conditions of a limestone slurry scrubber. All experiments were performed in a stirred cell contactor with separately agitated gas and liquid. Under typical conditions of a limestone slurry scrubbing, 10 mM total dissolved S(IV) and pH 4 to 5, the NO2 removal was less than 50 percent.

Yang, et al. [151 studied sulfite scrubbing for NO2 removal in their attempt to develop corona-induced chemical scrubbers for NOx emission control. At a gas mass flowrate of 90 lb/ft2 hr in their bench-scale packed bed scrubber, the NO2 removal was 98.8% and the outlet concentration was 1.1 ppm.

Although a considerable amount of work has been done on the reaction of NO2 with Na2S03, there are major gaps in developing Na2S03 aqueous solution for NO2 absorption. Of particular importance is the absorption rate of NO2 in a commercial scrubber. A pilot-scale program was initiated to evaluate the absorption rate of NO2 with Na2S03 aqueous solution in a packed tower. The research is directed at obtaining height of a transfer unit (HTU) for NO2 absorption, and the effects of major operation parameters, such as ORP, gas rate, liquid rate and Na2S03 concentration in the liquid on NO2 absorption.

dif I erent from that of a chemical scrubber. Shen and

CHEMICAL ABSORPTION IN A PACKED TOWER Consider a packed tower with the following char-

acteristics. The cross sectional area is S and the defer- ential volume, with respect to the height, dZ, is SdZ. If the change in gas molar flow rate Vis neglected, the amount of gas absorbed in section dZ is -V@, which is equal to the absorption rate times the differential volume:

-Vdy = K y 0 - y*) SdZ (5)

This equation is rearranged for integration by group- ing together the constant factors V; SdZ, and K y , which have a constant value with dZ.

The equation for the column height, Z F can be written by integrating dZ from 0 to Z;r; as follows:

fV \ (7)

z, =[-

The integral in Equation 8 represents the change in vapor concentration divided by the average driving force and is called the number of transfer units, NTU or No The other part of Equation 7 has the unit of length anl is called the height of transfer unit, HTU or Ho

The chemical reaction in the liquid phase reguces the equilibrium partial pressure of the solute over the solution, which greatly increases the driving force for mass transfer. If the reaction is essentially irreversible at absorption conditions, the equilibrium partial pressure is zero, and the N can be calculated just from the change in gas composition [261. For y* = 0. OY

The rate of absorption of NO2 can be evaluated by the overall mass transfer coefficient, K a. The two- film theory of mass transfer leads to tI!e following equation for K p , where the liquid-film mass transfer coefficient kx* is multiplied by an enhancement factor @ when there is a chemical reaction in the liquid film.

(9)

where m is the solubility of the gas phase reactant in water and k p is the gas film mass transfer coefficient. The enhancement factor depends on diffusivities and concentrations of both reactants in liquid and gas phas- es, and on the reaction rate constant. For a fast irreversible reaction and excess reactant in the solution, the enhancement factor, @ can be expressed as [271:

where k2 is the reaction rate constant, Bg is the initial concentration of reactant in the liquid and DA is the diffusivity of reactant in the gas phase.

EXPERIMENTAL SECTION The absorption tests were carried out at a pilot

plant built by Kunstoff Manufacturer, Co. Figure 1 shows the schematic of the gas scrubbing pilot plant. The plant consists of a gas blending system, a gas scrubber, a chemical injection and control system, and a NOx monitoring unit. The gas blending system is

226 December 2002 Environmental Progress (V01.21, No.4)

Table 1 . Experimental parameters and operating conditions.

Scrubber parameters Column diameter (ID) m 0.45 (16.2 in)

Packing height m 1.8 (5.9 ft) Packing size (nominal) in 3.25

Gas parameters Gas flow rate ft3/min, acfm 400 - 900 Gas mass flow rate lb/ft2 hr 1,000 - 2,500 Gas temperature (room) O C 25

Tower height m 5 (16.5 ft)

Gas composition (N02/air) PPm 200

Alkalinity (by NaOH) pH 11

Liquid parameters Liquid mass flow rate lb/ft2 hr 3,000 - 4,000

ORP (by Na2S03) mV -50 - -250

capable of producing a wide variety of gas composi- tions by mixing air with high concentration NO2 from cylinders. The N02-containing air stream is then passed through the scrubbing tower where the NO2 is absorbed and oxidized. Samples are taken to determine the inlet and outlet concentrations of NO2 and, through calculation, removal efficiencies and HTUs.

The gas blending system is capable of a total flow rate of 45 m3/min (1,600 cubic feet per minute, cfm). Concentrations are varied by injecting NO2 from a 5% gas cylinder through a mass flow meter. The system is made of glass fiber reinforced plastic (FRP), including the blower, except for the NO2 lines which are polypropy- lene tubing. After the NO2 is injected into the air stream, the whole stream is passed into a section of Tellerete Packing for better mixing. The well mixed N02-containing air stream is then carried into the gas scrubber, where absorption and chemical reaction occur.

The packed tower is constructed of a 5 meter long (16.5 ft) and 0.45 meter diameter (1.35 ft) polypropy- lene column with a section of 1.8 meter (5.9 ft) packed bed made by randomly packed 3.25 inch, No. 2 K-type Tellerete Packing. The top of the column holds a demister head packed with No. 1 R-type Tellerete Packing for removing entrained droplets from the gas stream. The entire column sits on a ves- sel which serves as the scrubbing solution reservoir.

The concentrations of Na2S03 in the scrubbing solutions are monitored and controlled by the oxidation reduction potential (ORP) metedmetering pump system. A circulating pump withdraws scrubbing solution from the reservoir and pumps it up to the top to be sprayed down on the packed bed, countercurrent to the gas flow. The rough pumping rate is controlled by regulating the recirculation rate, with the final adjustment being made at the Signet 5500 flow meter downstream from the pump.

A chemiluminescent NO, analyzer is used to measure NO2 concentrations. Basically, the signal from the NO, analyzer comes from the light emitted from the chemiluminescent gas phase reaction of nitric oxide and ozone. To measure NO concentration, the gas sample is blended with ozone in a reaction chamber. The ozone is generated in situ by a high voltage arc ozone genera-

tor. The resulting chemiluminescence is monitored through an optical filter by a high sensitivity photomulti- plier positioned at one end of the reaction chamber. The analysis is sensitive only to NO. To measure NO, concentrations, the sample gas is diverted through a high-temperature converter, where the NO2 is converted to N O , and the total of NO,, NO, plus N 0 2 , is detected as NO. The NO2 concentration is the differ- ence between the two readings for NO, and NO. Sig- nals from the NO, analyzer are continuously recorded.

RESULTS AND DISCUSSION The results from the scrubbing pilot plant research are

given in this section. Experiments were conducted at the conditions indicated in Table 1. Parameters, such as oxidation reduction potential and Na2SO3 concentrations in the scrubbing solutions, gas velocity, and liquid mass flow rate, as well as gas and liquid flow rates, were studied for their effect on NO2 absorption. A set of operating conditions was established after these tests, and based on these operating conditions, the HTU for NO2 absorption in the packed bed is correlated to gas flow rate for further study and full-scale scrubber design.

In the first series of tests, the tower was operated at various gas velocities in order to find out a reasonable contact time between NO2 and S03-2 in the scrubbing solution. At a gas velocity of 2.7 m/s (8.9 ft/s) and a liquid rate of 40 L/min (3,000 lb/ft2 hr), the NO2 removal was 60 percent. The removal rate increased with the decrease of gas velocity, as shown in Figure 2. At a higher sulfite concentration, 0.25 molar (M), the NO2 absorption was more than 99% when the gas velocity was reduced to 1.2 m / s (4 ft/s). A gas velocity of 1.2 m / s represents a 1.5 second contact time between NO2 and S03-2 in the scrubber. It is clear that high NO2 absorption would require operation at gas velocities less than 1.2 m/s .

Other runs were made with two volumetric gas rates, 11.3 and 22.7 m3/min (400 and 800 ft3/min, cfm) to test the effect of S03-2 concentration on NO2 absorption. The concentration of SOg2 was controlled and monitored by an ORP meter. At a gas rate of 22.7 m3/min, the NO2 absorption was about 45% at an ORP of -50 mV. The negative ORP indicates that sulfite is a reducing

Environmental Progress (V01.21, No.@ December 2002 227

NO2

W Blower Mixer

Analyzer T* Demiater

nozzl

Packec bed

r5!!mp Overflowl I

Pump

; 45% NaOH i 12% Na2S03

Figure 1. Schematic of the pilot plant gas scrubbing system.

agent and its concentration is only proportional to the value. The NO2 absorption increased with the S03-2 concentration, expressed as oxidationheduction potential in millivolts. At a lower gas rate, 11.3 m3/min, NO2 absorption increased from 75% to 96% when OW was increased from -50 to -240 mV, as shown in Figure 3. The differences of NO2 absorption between the two gas flow rates were 13% to 27% over the same range of OW. The gas rate of 11.3 m3/min represents a 1.5 second contact time between NO2 and S03-2 in the packed tower while the -240 mV represents a sulfite concentration of 0.25 M in the scrubbing solution.

The next set of experiments was designed to quantlfy the effects of liquid flow rate on NO2 absorption. The gas rate was varied from 1,000 to 2,400 lb/ft2 hr. The OW in the liquid was maintained constant at -240 mV. At a liquid rate of 3,000 lb/ft2 hr, NO2 absorption ranged from 65% to 94%, as shown in Figure 4. The experiment was repeated with a liquid rate of 4,000 lb/ft2 hr. In the same range of gas rate, when liquid rate was increased from 3,000 to 4,000 lb/ft2 hr, NO2 absorption increased 3% to 6%. Liquid rate has a smaller effect on NO2 absorption in the packed tower. This confirms that absorption rate, in terms of number of transfer units, varied inversely with gas velocity, and increased with the 0.4 to 0.6 power of the liquid rate.

A number of experiments were performed at the conditions indicated in Table 1 with 0.15 and 0.25 M sodium sulfite scrubbing solution. The gas rate was varied from 11.3 to 25.4 m3/min (400 to 900 cfm). The liquid rate was maintained at 4,000 lb/ft2 hr. Thus, the practical range of 1.7 to 3.7 liquid to gas mass ratio

(UG) was studied. The actual measurements from these experiments are plotted in Figure 5. The data indicate that the scrubbing effectiveness of NO2 increased with the V G ratio, and an V G of more than 3 is required for high NO2 absorption. Operating at a higher liquid rate can be justified by keeping L/G greater than 3, even though the effect of liquid rate on NO2 absorption is smaller than that of gas rate.

For absorption of NO2 in water, the solubility is only 0.04 M/atm at 25" C . However, the low solubility can be improved by a big enhancement factor rovid-

enhancement factor depends on diffusivities and concentrations of both NO2 and S03-2, and on the reaction rate constant. For a fast irreversible reaction, and with excess S03-2 in the solution, the enhancement factor, $ can be estimated from Equation 11 with DA = 2 x 10- cm2/s [281, BO = 0.25 M, kL* = 0.01 cm/s, and k 2 = 11 x lo5 1251.

ed by the rapid reaction of NO2 with SO3- 5 . The

(11) (1 1 x lo5 x 0.25 x 2 x 10-~)0.~

= 235 0.01 @NO,

The value is large, but it is not large enough to com- pensate for the much lower solubility. The liquid-film resistance is still much greater than gas-film resistance. This hypothesis is supported by the ex erimental data

is still strongly affecting the overall mass transfer rate in in Figure 6. The result shows that SO3- 5) in the solution


1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 G u ssloelty (mla)

Figure 2. The effect of gas velocity on NO2 absorption in a packed bed scrubber.

NO2 removal (%)

1000 1200 1400 1600 1800 2000 2200 2400 Ou r8te (IblftA2-hr)

Figure 4. The effect of gas mass rate on NO2 absorption at liquid rate of 3,000 and 4.000 lb/ft2 hr.

terms of HTLJ, through enhancement factor, and through liquid film mass transfer coefficient.

CONCLUSIONS The Na2S03 aqueous solution is effective for NO2

removal in a packed bed scrubber. NO2 absorption occurs with simultaneous mass transfer and fast chemical reaction. At a sulfite concentration of 0.25 M, and a gas- liquid contact time of 1.5 seconds, NO2 absorption was more than 33%. The Na2SO3 creates an irreversible reaction to drive NO2 to the scrubbing solution. Even with 0.25 M sodium sulfite in the scrubbing solution, the liquid-film resistance still controls the absorption of N02. The enhancement effect is due to reaction of NO2 with S03-2. A sulfite concentration of 0.25 M is essential for a reasonable HTU in 2 to 5 feet for a gas rate between 1,050 to 2,350 lb/ft2 hr. The results also indicate that the scrubbing effectiveness of NO2 increased with the V G ratio and an VG of more than 3 is required for high NO2 absorption. Since Na2S02 in the solution increases both the enhancement factor and solution capacity for NO2 absorption, operating at a higher concentration can be justified. The ORP can be used to monitor and control the concentration of Na2S03 in the scrubbing solution. An ORP of -240 mV is adequate for a 99% NO2 removal.

NO2 n m d (%) 100

80

60

40

20

0 -300 -250 -200 -150 -100 -50 0

(hidatloo redoction potential (mV)

Figure 3. The effect of oxidation reduction potential on NO2 absorption with gas rates at 400 acfm and 800 acfm, and liquid mass flow rate at 4,000 Ib/ft2 hr.

NO2 r o m d (%) 100

80

60

40

20

0 1 1.5 2 2.5 3 3.5 4

LIG n t l o Figure 5. The effect of liquid-gas mass ratio (VO on NO2 absorption at sulfite concentrations of 0.15 and 0.25 M.

ACKNOWLEDGMENT The authors are grateful to Arthur Lee, President of

Kunstoff Manufacturer Co., Taipei, Taiwan, for support of this research.

LITERATURE CITED 1. Chappe l l , G.A., “Development of Aqueous

Processes for Removing NOx from Flue Gases,”

2. Shaw, H., “Aqueous Solution Scrubbing for NOx Control in Munitions Incineration,” ASME Winter Annual Meeting, Paper No. 76-WMFU-9, New York, NY, 1976.

3. Senjo, T. and M. Kobayashi, “Removal of Nitro- gen Oxides from Waste Gases,” Japanese Patent 49130362, 1973.

4. Hartmann, H.F., G.M. Brown, and B. Kean, “Use of Chlorine Dioxide to Reduce Vapor Phase Gum in Town Gas,” J. Inst. Fuel, 39, pp 325-335, 1966.

5. Hixon, E.M., “Removal of Nitric Oxide from Gas Streams via Direct Chlorine Injection,” AFRC Inter- national Symposium, Paper No. 36, 1990.

6. Brogren, C., H.T. Karlsson, and I. Bjerle, “Absorp- tion of NO in an Aqueous Solution of NaClO2,” Chemi- CalEngineering Tmhmhgy, 21, pp 61-70,1998.

EPA-R2-72-051, 1972.

Environmental Progress (V01.21, No.4) December 2002 229

HTU (ft) 8 , I I I I I I I

1 -

0 1000 1200 1400 1600 1800 2000 2200 2400

GM rate (IblltAZ-hr)

Figure 6. The effect of gas mass flow rate on HTU for NO2 absorption in a packed bed scrubber at sulfite concentrations of 0.15 and 0.25 M.

10.

11.

12.

13.

14.

15.

16.

~~ ~~

17. Haythornthwaite, S.M., et aL , “Evaluation of Pilot-Scale Pulse-Corona-Induced Plasma Device to Remove NOx from Combustion Exhausts from a Subscale Combustor and from Hush House at Nellis AFB, Nevada,” AL/EQ-TR-1997-0022, ADA Technologies, Inc., 1997.

18. Lee, Y.N. and S.E. Schwartz, Precipitation Scav- enging, D y Deposition, and Resuspension, H.R. Pruppacher, W.G.N. Slinn, Editors, Elsevier, New York, NY, p 453, 1983.

19. Nash, T., “The Effect of Nitrogen Dioxide and of Some Transition Metals on the Oxidation of Dilute Bisulfite Solutions,” Atmospheric Environment,

20. Cofer, W.R., et al., “The Oxidation of SO2 on Carbon Particles in The Presence of 0 , NO2 and N 2 0 , ” Atmospheric Environment, l?, pp 1281- 1286, 1981.

21. Ellison, T.K. and C.A. Eckert, “The‘ Oxidation of Aaueous SO?. 4. The Influence of Nitrogen Diox-

13, pp 1149-1154, 1979.

ide at Low pfi,” Journal of Physical Chemisty, 88, Yang, C.-L. and H. Shaw, “Auueous Absomtion of . . . _ _ I . *

Nitriz-Oxide Induced by Sodium Chlorite Okdation in the Presence of Sulfur Dioxide,” Environmental Progress, 17, 2, pp 80-85, Summer 1998.

tion of NO Promoted by Strong Oxidizing Agents: 1. Inorganic Oxychlorides in Nitric Acid,” Chemical Engi- neering Communications, 143, pp 23-38,1996. Robenson, S., “Hydrogen Peroxide: First Aid for Air Pollution,” The National Environmental Jour- nal, May/June 1993. Stromblad, L., “Absorption of Nitrogen Oxides,” Licentiate Thesis, University of Lund, Sweden, 1988. Tri-Mer Corp., “NO Scrubber Improves Emissions,” Pollution Equ@ment Nms, p 52, April 1997, Environair, “Treatment of Gas Effluent from Incin- eration of Various Chemical Products,” Lubben Project, Lubben, Germany, 1994. Anderson, M.H. and A.P. Skelley, “A Low-Tem- perature Oxidation System for the Control of NOx Emissions Using Ozone Injection,” Institute of Clean Air Companies, Forum ’98, Durham, NC, 1998. Yang, C.-L. and D. Meier, “Cleaning Flue Gas from Sewage Sludge Incinerators Using an Elec- trostatic Precipitator and Polystage Chemical Scrubber,” J. of Air & Waste Manag. Assoc., 49, pp

Yang, C.-L., M.R. Beltran, 2. Kravets, and T. Yamamoto, “Corona-Induced Chemical Scrubber for the Control of NOx Emissions,” Environmen- tal Progress, 17, 3, pp 183-189, Fall 1998. Yang, C.-L., “Pulse-Energized Wet Tubular Elec- trostatic Precipitator for NOx Emission Control,” Environmental Progress, 18, 2, pp 80-86, Summer 1999.

Yan& C.-L, H. Shaw, and E D . M h m , ‘‘AbSOP

169-176, 1999.

22.

23.

24.

25.

26.

27.

28.

11, 1984. Rosenberg, H.S. and H.M. Grotta, “NO, Influ- ence on Sulfite Oxidation and Scaling in Lime/Limestone Flue Gas Desulfurization (FGD) Systems,” Environmental Science & Technology, 14, 4, pp 470-472, American Chemical Society, Washington, DC, 1980. Clifton, C.L., N. Altstein, and R.E. Hule, “Rate Constant for the Reaction of NO2 with Sulfur(1V) over the pH Range 5.3-13,” Environmental Sci- ence & Technology, 22, 5, pp 586-589, American Chemical Society, Washington, DC, 1988. Littlejohn, D., Y. Wang, and S.-G. Chang, “Oxi- dation of Aqueous Sulfite Ion by Nitrogen Diox- ide,” Environmental Science & Technology, 27, 10, pp 2162-2167, American Chemical Society, Washington, DC, 1993. Shen, C.H. and G.T. Rochelle, “Nitrogen Diox- ide Absorption and Sulfite Oxidation in Aqueous Sulfite,” Environmental Science & Technology, 32, 13, pp 1994-2003, American Chemical Society, Washington, DC, 1998. McCabe, W.L., J.C. Smith, and P. Harriott, Unit Operations of Chemical Engineering, 4th Edition, McGraw-Hill, New York, NY, 1985. Sherwood, T.K., R.L. Pigford, and C.R. Wilke, Mass Transfer, McGraw-Hill, New York, NY, 1975. Lide, D.R., CRC Handbook of Chemistry and Physics, CRC Press, 1990.


absorption of no2 in a packed tower with na2so3 aqueous solution

Documents