&EPA United States Industrial Environmental Research Environmental Protection Laboratory Agency Research Triangle Park NC 27711 EPA-600/8-78-005b June 1978 Research and Development Participate Control Highlights: Performance and Design Model for Scrubbers BY-PRODUCTS OR RECYCLE STREAMS PUMP SOLID LIQUID WASTE WASTE ------- RESEARCH REPORTING SERIES Research reports of the Office of Research and Development, U.S. Environmental Protection Agency, have been grouped into nine series. These nine broad cate- gories were established to facilitate further development and application of environmental technology. Elimination of traditional grouping was consciously planned to foster technology transfer and a maximum interface in related fields. The nine series are: 1. Environmental Health Effects Research 2. Environmental Protection Technology 3. Ecological Research 4. Environmental Monitoring 5. Socioeconomic Environmental Studies 6. Scientific and Technical Assessment Reports (STAR) 7. Interagency Energy-Environment Research and Development 8. "Special" Reports 9. Miscellaneous Reports This report has been assigned to the SPECIAL REPORTS series. This series is reserved for reports which are intended to meet the technical information needs of specifically targeted user groups. Reports in this series include Problem Orient- ed Reports, Research Application Reports, and Executive Summary Documents. Typical of these reports include state-of-the-art analyses, technology assess- ments, reports on the results of major research and development efforts, design manuals, and user manuals. EPA REVIEW NOTICE This report has been reviewed by the U.S. Environmental Protection Agency, and approved for publication. Approval does not signify that the contents necessarily reflect the views and policy of the Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. This document is available to the public through the National Technical Informa- tion Service, Springfield, Virginia 22161. ------- EPA-600/8-78-005b June 1978 Participate Control Highlights: Performance and Design Model for Scrubbers by S. Yung and S. Calvert A.P.T., Inc. 4901 Morena Boulevard, Suite 402 San Diego, California 92117 Contract No. 68-02-2190 Program Element No. EHE624 EPA Project Officer: Dennis C. Drehmel Industrial Environmental Research Laboratory Office of Energy, Minerals, and Industry Research Triangle Park, NC 27711 Prepared for U.S. ENVIRONMENTAL PROTECTION AGENCY Office of Research and Development Washington, DC 20460 ------- ABSTRACT When EPA initiated the Wet Scrubber Systems Study in 1970 the state-of-the-art was largely empirical. Each application was considered to be a special case which could only be dealt with on the basis of long and specific experience. Engineering design was based on a primitive, cut-and-try approach and often resulted in an expensive overdesign to cover the wide range of uncertainty. There was also very little scrubber performance information available. In the Wet Scrubber Systems Study all available information concerning wet scrubber theory and practice was reviewed and evaluated. The best available engineering design methods were evaluated and where necessary new or revised methods were developed to provide as sound a basis as possible for predicting performance. The result of this study was the publication in 1972 of the "Scrubber Handbook." This capsule report summarizes the best available design models for wet scrubbers. Details of the models are reported in the Scrubber Handbook and other EPA publications listed in the bibliography. ii ------- CONTENTS Abstract ii Figures iv Tables iv Abbreviations and Symbols . v Introduction 1 Collection Mechanisms 1 Design Equations 2 Unit Mechanism Approach 2 Deposition Velocity Approach 3 Pressure Drop -.4 Performance Prediction and Scrubber Design 4 Cut Diameter Method for Performance Prediction and Scrubber Design 5 Cut Diameter 5 Integrated Penetration 6 Cut/Power Relation 7 Power and Cost 8 Bibliography 19 iii ------- FIGURES Number Page 1 Relation Between Physical and Aerodynamic Particle Diameter 14 2 Experimental and Calculated Collection Efficiencies for Sphere and Cylinder 15 3 Predicted Particle Diameter, Penetration Relation- ship for Inertial Impaction 16 4 Integrated (Overall) Penetration as a Function of Cut Diameter and Particle Parameters 17 5 A.P.T. Cut/Power Plot 18 TABLES Number 1 Scrubber Classifications 9 2 Design Equations for Various Scrubber Types 10 3 Single Drop and Single Cylinder Collection Efficiency Due to Various Collection Phenomena 11 4 Particle Deposition Velocity 12 5 Pressure Drop 13 iv ------- A - A • A_ • t B - C • C • C' - CD- Ci ' Co- D. • d - pa 4PI E • P F • f - f(dp) g H h Pt kc I • LIST OF ABBREVATIONS AND SYMBOLS cyclone inlet area, m' dinensionless constant in equation (6) cross-sectional area of the collector normal to gas flow direction, •* deposition area, a* projected area of baffles, m1 cross-sectional area of duct, m* dinensionless constant in equation (6) cyclone geometry parameter, dimensionless particle concentration, g/a1 Cunningham slip correction factor, dimensionless drag coefficient, dimensionless particle concentration at the scrubber inlet, g/m1 particle concentration at the scrubber outlet, g/m1 cyclone diameter, n particle diffusivity, »2/s molecular diffusivity, ml/s collector diameter, m drop diameter, n cyclone exit diameter, m fiber diameter, m sieve plate perforation diameter, m particle diameter, n or ura aerodynamic particle diameter, lunA mass median diameter, n or UraA required cut diameter, umA collection efficiency, fraction charging electric field strength, v/m effective precipitating electric field strength, v/m foam density, dimensionless empirical constant • O.S drag coefficient, dimensionless fraction of hole area, fraction frequency distribution of particles acceleration of gravity, m/s1 magnetic field strength, A/m distance of drops traveled, m inertial inpaction parameter, dimensionless inertial parameter at the throat, dimensionless gas thermal conductivity, J/a-s-'K particle thermal conductivity, J/m-s-'K thickness of fibrous packing, a "Pe »Re P PT R • PG T "Gt uh UPD ut W A • Greek cylinder drop 'pot nvis a Pw &P aolecular weight of gas, g/g-aol aolecular weight of vapor, g/g-nol Peclet number, diaensionless Reynolds nuaber, dioensionless absolute pressure, Pa overall particle penetration penetration for particles with diameter d , fraction radius, a gas volumetric flow rate, m'/s liquid volumetric flow rate, m'/s collector charge, C particle charge, C gas partial pressure, Pa gas temperature, *K gas velocity passing the collector, m/s gas velocity, m/s gas velocity at the throat, m/s gas velocity through perforation, m/s particle deposition velocity, m/s terminal settling velocity, m/s mass of particles, g weir length, m depth of packing, m fiber fraction, fraction dielectric constant, dimensionless porosity, fraction permitivity constant (8.8S4 x 10" coulomb'/nt-n'J overall collection efficiency of a unit mechanism, dimensionless single cylinder collection efficiency, fraction particle collection due to diffusion, fraction single drop collection efficiency, fraction particle collection due to electric precipitation, fraction particle collection due to gravity, fraction particle collection efficiency due to impaction, fraction potential flow drop collection efficiency, fraction viscous flow drop collection efficiency, fraction angle of attack, degree penetration time, s geometric standard deviation, dimensionless gas absolute viscosity, kg/a-s particle density, kg/m1 density of water, kg/m1 pressure drop, cm W.C. dry pressure drop, ca W.C, ------- PERFORMANCE AND DESIGN MODELS FOR SCRUBBERS INTRODUCTION Scrubbers are devices which utilize a liquid in the separa- tion of particulate or gaseous contaminants from a gas stream. The liquid may be used to contact the gas and particles directly, or may be used to clean solid surfaces on which the particles or gases have been collected. Scrubbers are used extensively for the control of air pollu- tion emissions. There are so many different scrubber systems offered by manufacturers that it is often difficult to choose the right scrubber for a particular job. The optimum scrubber system for a particular job will not depend only on the system costs. The major consideration should be whether the scrubber is capable of removing the pollutants to the degree required. An inexpensive, simple scrubber which does not meet the efficiency requirements is not only useless, but a waste of money and time. It is, therefore, of primary im- portance to provide as sound a basis as possible for predicting performance. Design models based on fundamental engineering concepts provide the best approach for evaluating the performance and cost of scrubber systems. This report summarizes the best available engineering models for particulate scrubbers. COLLECTION MECHANISMS Currently available scrubbers can be grouped into a number of categories: plate, massive packing, fibrous packing, preformed spray, gas-atomized spray, centrifugal, baffle, impingement and entrainment, mechanically aided, moving bed, and various combina- tions (Calvert, et al. 1972 and Calvert, 1977). No matter what ------- type of scrubber is being evaluated, it is convenient to consider dust particles to be separated from the gas by one or more unit mechanisms, the basic particle collection elements which account for the scrubber performance. For example, in a venturi scrubber, particle collection is achieved by contacting the par- ticles with the atomized liquid drops. Thus, collection by drops is a unit mechanism. Other unit mechanisms for particle collec- tion include collection by cylinders, sheets, bubbles, and jet impingement. Table 1 summarizes the scrubber groups and the impor- tant unit mechanisms for each group. For each of the unit mechanisms, the particles are separated from the gas by one or more of the following particle collection mechanisms: gravitational sedimentation, centrifugal deposition, inertial impact ion, interception, Brownian diffusion, thermophore- sis, dif fusiophoresis and electrostatic precipitation. Particle collection also may be enhanced by increasing the particle size through agglomeration, condensation, or other particle growth mechanisms. DESIGN EQUATIONS There are two basic approaches for developing design equations for scrubbers. One approach is to consider the collection effi- ciency of individual unit .mechanisms , such as collection by single drops, and derive a relationship for the overall collection efficiency based on the unit mechanisms. The second approach is to determine the deposition velocity of a particle experiencing a specific deposition force, such as electrical attraction. These two approaches are discussed below. Unit Mechanism Approach The general design equation which describes particle collec- tion by any control device in which the gas and dust are well mixed is: dc u r dA (1) c ------- "n" is the overall collection efficiency of a unit mechanism. Inertial impaction is the collection of moving particles by impingement on some target. The relative effect of inertial impaction for different particles and flow conditions is charac- terized by the inertial impaction parameter, K , defined as: Cf p dfur K = P-P-G (2) P 9 *G dc Figure 1 shows the theoretical and experimental target effi- ciencies for a single sphere and a single cylinder as related to tLe inertial impaction parameter. Equation (1) has been solved for various scrubber systems which involve collection by inertial impaction. The results are tabulated in Table 2. Equation (1) also may be applied to other collection mechan- isms if an expression for "n" is known. Table 3 presents expres- sions for the single drop and single cylinder collection efficien- cies resulting from various collection mechanisms. Deposition Velocity Approach The particle deposition velocity is the component of its velocity in the direction towards the collecting surface. If the particle deposition velocity is constant and the gas and par- ticles are well mixed everywhere in the scrubber, the particle collection can be predicted from the following equation: c o Pt, = 1-E = — = exp ci UPD AD (3) "u D" is the net particle deposition velocity caused by the col- lection mechanism(s). The deposition velocity for any collection mechanism depends on the force balance between the driving force (deposition force) and the resistance force of the gas. Table 4 ------- is a list of theoretical equations predicting the deposition velocity for each collection mechanism. The scrubber collection efficiency can be calculated by using equation (3) coupled with the appropriate deposition velocity and the total deposition area of the scrubber. Pressure Drop Along with particle collection efficiency, the scrubber power requirement is also an important consideration in designing the optimum pollution control system. The power requirement for particle scrubbing is mainly a function of the gas pressure drop. Preformed sprays and mechanically aided scrubbers have signifi- cant power inputs to pumps and other devices. Equations for predicting the gas phase pressure drop for various types of scrubbers are summarized in Table 5. PERFORMANCE PREDICTION AND SCRUBBER DESIGN Air pollution control regulations generally specify a maxi- mum mass rate of emissions and often set a concentration limit as well. By knowing the particulate concentration and mass rate at the scrubber inlet, one can specify the minimum collection efficiency or the maximum allowable penetration through the scrubber being designed or selected. When a range of particle sizes is involved, as generally is the case, the overall particle penetration will depend on the size distribution and on the penetration for each size. The overall penetration, Ft, of any device collecting a dust with any size distribution will be: -w Pt, dW f Ptd dW _ f J W / Ft = W J a " P The right-hand side of the above equation is the integral of the product of each weight fraction of dust times the penetra- tion of that fraction. ------- In designing a scrubber, the maximum allowable penetration, Ft, and size distribution, f (d ) , in the process stream must be known. The only variable in equation (4) is "Ptd" which is a function of scrubber geometry and scrubber operating conditions. One must first choose the scrubber geometry and operation condi- tion, then evaluate "Pt^" by means of the design equations presen- ted in Table 2 and integrate equation (4) to obtain the overall penetration, Ft. If the calculated "Ft" is greater than the allowable maximum, new scrubber geometry and operating conditions are chosen and the calculations are repeated. These trial and error procedures are continued until one arrives at a scrubber design which gives an overall penetration smaller than or equal to the maximum allowable "Ft." Generally, more than one scrubber geometry and set of operating conditions give satisfactory performance. The final selection will be based on cost, experience and other factors. Choosing a scrubber is simpler than designing one. The scrubber manufacturer's proposed geometry and operating condi- tion may be used to calculate "Ptj" from the appropriate design equations. Then "Ft" may be calculated from equation (4) to check whether it is acceptable. This design method is precise but time-consuming. A much simpler method, called the "cut diameter" method, has been developed to provide quick designs when precision is not required. The "cut diameter" method has been described in the "Scrubber Handbook" and other publications. CUT DIAMETER METHOD FOR PERFORMANCE PREDICTION AND SCRUBBER DESIGN Cut Diameter A very convenient parameter for describing the capability of a particle scrubber is the diameter of the particle for which the scrubber is 501 efficient. This diameter is referred to as the cut diameter, generally given in aerodynamic units. Thus, a scrubber with a cut diameter of 1.0 ymA would collect particles of 1 ymA size at 501 efficiency. ------- The great utility of cut diameter stems from the fact that a curve of collection efficiency versus particle diameter for col- lection by inertial impaction is fairly steep. Several important types of scrubbers have performance characteristics such that a particle whose aerodynamic diameter is half the cut diameter would be collected at about 10% efficiency, whereas a particle with an aerodynamic diameter twice the cut diameter would be collected at about 90% efficiency. Because the cut is fairly sharp, one can use as a rough approximation the concept that the scrubber collects everything larger than the cut diameter and passes everything smaller. Integrated Penetration Most scrubbers that collect particles by inertial impaction perform in accordance with the following relationship: / B \ c Ptd = exp -A d )= - (5) "B" is an empirical constant. Packed-bed and plate type scrubber performance are described by a value of "B = 2.0" whereas for centrifugal scrubbers of the cyclone type, B = 0.7. Gas-atomizing scrubber performance fits a value of "B = 2.0" over a large portion of the usual operating range. Therefore, we use a value of "B = 2.0" as representative of most scrubbers operating in the inertial impaction regime. Figure 2 plots collection efficiency against the ratio of aerodynamic particle diameter to performance cut-diameter, showing one line based on equation (5) and another for a venturi scrubber under typical operating conditions. Most industrial particulates have approximately a log-normal size distribution. Hence, the two basic parameters of the log- normal distribution adequately describe the size distributions of particulate matter. These parameters are the mass median diameter, d , and the geometric standard deviation, o . If the Jr & ** size distribution is log-normal, a plot of the percent of particles ------- less or greater than a stated diameter versus the diameter, on logarithmic probability graph paper, will yield a straight line. The 50% value of "dpa" equals "dpg" and the ratio of the particle diameter at about 84.1% undersize to "d " is equal to "a ." One can integrate equation (4) with "Ptd" given by equation (5) and "f(dp)M by log-normal distribution. The results are presented in graphical form in Figure 3. The overall penetration (FT) for the entire size distribution is plotted against the ratio of required cut diameter to mass median diameter, with geo- metric standard deviation as the parameter. Figure 3 can be used to determine what "dRC," the required cut diameter, must be in order to get a specific "PT" for a given size distribution. For example, suppose the size distribution has "dpg = 10 ymA" and "ag = 3-°>" and one needs 99% collection efficiency. The penetration is 1001 minus the percent collection efficiency, or 1%, which corresponds to "Ft = 0.01" in fractional units . The diameter ratio corresponding to "Pt = 0.01" and "a = 3.0" is "dRC/dpg = 0.063." Since "dpg = 10 ymA, dRC = 0.63SymA." This means that one will need a scrubber with a cut diameter of 0.63 ymA or less to achieve 99% collection of the particles in question. Cut/Power Relation Mathematical models for scrubber performance and the cut- diameter approach developed in the "Scrubber Handbook" led to the concept that performance cut diameter could be related to gas- phase pressure drop, or power input to the scrubber. The results of subsequent performance tests on a variety of scrubbers in industrial installations, combined with mathematical modeling, enabled the refinement of the cut/power relationship shown in Figure 4. The curves give the cut diameter (ymA) as a function of either power input (W/m3/min) or gas-phase pressure drop (cm W.C.) for a number of typical installations such as sieve-plate column, packed column, fibrous packed bed, gas-atomized spray, and mobile fluidized bed. ------- The A.P.T. cut/power relationship has been devised and tested on the basis of all the published data available. It appears to be an accurate and reliable criterion for scrubber selection. One can see from Figure 4 that the only "unaided" scrubbers capable of giving a 0.6 umA cut diameter are the gas-atomized and fibrous-packed-bed types. A gas-phase pressure drop of about 33 cm W.C. would be required for the gas-atomized scrubber. The fibrous packing would need 56 cm W.C. for 100 ym fiber diameter and about 15 cm W.C. for 50 pm fibers. It would take about 75 ym fiber diameter to achieve a "dDP - KL 0.6 ymA" at slightly less pressure drop than for the gas-atomized scrubber. This is quite fine fiber or wire, and serious questions would arise regarding its structural stability, and susceptibility to corrosion and plugging. The safe approach would be to choose the gas-atomized scrubber unless extensive pilot tests could be done with fine fiber beds. Other types of scrubbers could achieve the required per- formance if augmented by F/C effects or by electrostatic charging. Each system would have to be examined to determine whether it would be economically attractive. Power and Cost The equivalent power axis plotted on the top of the cut/ power plot is based on 501 efficiency for a fan and motor combination. The theoretical power requirement is approximately 1.63 W/m'/min for each centimeter of water pressure drop. Power costs can be approximated as twice the theoretical power required for 50% efficiency. Equipment costs are best estimated from vendor's quotations. As usual, one must be sure that all prices for competing units are on the same basis. Materials, ducting, electrical work, foundations, supporting structure, etc., must be specified as included or not. ------- TABLE 1. SCRUBBER CLASSIFICATIONS Geometric Type Unit Mechanism for Particle Collection Plate Massive packing Fibrous packing Pre-formed spray Gas-atomized spray Centrifugal Baffle and secondary flow Impingement and entrainment Mechanically aided Moving bed Combinations Jet impingement, bubbles Sheets (curved or plane), jet impingement Cylinders Drops Drops, cylinders, sheets Sheets Sheets Sheets, drops; cylinders, jets Drops, cylinders, sheets Bubbles, sheets ------- TABLE 2. DESIGN EQUATIONS I-OK VAH10US SCRUBBED TVI'tS SCRUBBER TYPE DESIGN EQUATIONS Sieve Plate Pt - exp [-40 F'K ]. K . O.J8 < F < 0.65 Massive Packing Pt Fibrous Packing Pt , - exp - ^— an • Id cylinder "cylinder ' f(V' fr°m fifa* * Venturi and Cas-Atonized Spray Gc F(Vf).^^l,tn(!H^)._P^_ - (Kpt f « 0.7) Preformed Spray r 3 QL ut z d" "p * •>n A ,—; ndr°p L 2 QC d d (ut-U(.) "P f 3 QL h -1 Ptd * "P ' TTT" "drop • ««>SS-flOV L 2 QG dd J . vertical countercurrent flow drop ' fr°m Fi«u« 2 Impingement and Entrainment Pl , cxp ) d ] - i F {r f) C^G ' J 0.7 - (Kpt,f « 0.7) 0.7 * Kpt.f Centrifugal (cyclone) Ptd - exp [.2(C ,, (it + D [(0.00394 D ) ~\ i - \ 1 TT^-Jfe Centrifugal (cyclone with spray) ptj "drop P f(V' fr°B FigU" and n saae as Thmt for the cyclone Baffle Type Collector ••t) "I "'drop " *'"»'• *ro* F1*ure ' 10 ------- TABLE 3. SINGLE DROP AND SINGLE CYLINDER COLLECTION EFFICIENCY DUE TO VARIOUS COLLECTION PHENOMENA COLLECTION PHENOMENA DROP CYLINDER Interception = 0.0518 , laminar flow I. d f P , turbulant flow Diffusion D U_,-u, 1 d, 2+0.552 |U_,-u, 1 , | G d| d 0.5 /VG\I NRedVV /3 -0.6 Gravity Settling n . I) _ NRed 60 C' dp pp 18 y U Electrostatic Precipitation 4 C' q q n M -, charged particle 3 IT p d u e charged drop p o o nc = i.s q 24 , uncharged particle charged drop 12 ir2e dr2yr d u o f G p o _ 0,5 ------- TABLE 4. PARTICLE DEPOSITION VELOCITY Collection Phenomena Gravitational Sedimentation Centrifugal Deposition Brownian Diffusion Thermophoresis n~i ~ff 11 i rcnViOTp i <; Electrical Migration Magnetic Precipitation Particle Deposition Velocity „ _ 1 C> dp CPp-PG)g PD 18 . yn u ! C- dj (pp-PG) ut« PU 18 MG R -pD-^»ftr 3 C' yr / kr \ u „ _ G / G 1 VT PD 2 pG T \2 kG.kpj u - M^°'5 P DVG »p PU PvV'PGV PG V u . e C'EoEcEp dp PD e + 2 4 TT ?G C1 y H q yf . PD , , 3 TT y.-, d^ u P 12 ------- TABLE 5. PRESSURE DROP Scrubber Type Sieve Plate Massive Packing Fibrous Packing Venturi and Gas Atomized Spray Centrifugal (cyclone) Baffle Pressure Drop iP • hw + how + hdp * hr h = weir height z 5 cm W Q, how ' O-157 5Jf 2 Pr U? h = 1 14 TO 4 fl 25-f "1 + fl £11 dp L lJ..*.a rjjJ*U ijjj J p hr • °'13 j% Generalized pressure drop correlation for bed (Perry, 1973). o ri-p^ p c u 2 !* X/^J. tj (i ^i-> Up AP - 6 5 x 10" b D b df packed • , /QL\ AP = 8.24 x 10 uGt2(o^) AP — n nnfl^l1? r> 1 vall/.O A! vritVi in1f»1" v (j \ A/I Q / /O V/16 A\ i "n 1 1 ./_ I i«ri tVirmt1 -irtl^t1 = 0.000513 PG U£H d2y» without inlet * A/ 6 n 3 f n G P AP = Z 1.02 x 10 D MG 2 COS2Q A anes vanes 13 ------- 50 £ 10 Di 2 5 I—I Q w u a, u >—i £ c o a; (14 < 0.5 0.1 I III' I I I 1 I I 0.1 Pp - 4. g/cnr I I l i I 1 i I I J |_ I I t I I I I 0.5 1.0 S PARTICLE DIAMETER, ym 10 20 Figure 1. Relation between physical and aerodynamic particle diameter. 14 ------- 1.0 .9 u- P* .7 .6 .5 § i—i I -4 i—3 8 .3 .2 .1 0 I I I I I I l | i I 0.1 0.2 0.3 0.5 1.0 10 Figure 2. Experimental and calculated collection efficiencies for sphere and cylinder. ------- 3.0 2.0 i i.o e n. o 03 0.5 0.1 I I I 1111 I I I I I I I 11 I I I Pt = exp - (A cTa) TYPICAL PREDICTION FOR \ VENTURI SCRUBBER \ \ N i i linn i i i i 11111 i i i i i in 11i i i 0.1 0.51 2 10 SO PENETRATION FOR d , I pa 90 95 98 99 Figure 3. Predicted particle diameter, penetration relationship for inertial impaction (Calvert , 19741. ------- 1.0 EX #s 2: o KH E- E^ 2; < 0.01 o.i r 0.001 Pt = exp (-A d2 ) ^ j 0.001 0. 001 0.1 1.0 Figure 4. Integrated (overall) penetration as a function of cut diameter and particle parameters. ------- 20 os w E- W Q E- 1.0 0.2 SCRUBBER POWER, W/.m3/min 50 100 200 I I I I 500 0.5 50 100 GAS PHASE PRESSURE DROP, cm W.C. Figure 5. A.P.T. cut/power plot 200 la. Sieve-plate column with foam density of 0.4 g/on3 and 0.5 mm hole dia The number of plates does not affect the relationship much (Experimental data and mathematical model.) Ib. Same as la except 3.2 mm hole dia. 2. Packed column with 1-in. rings or saddles. Packing depth does not affect the relationship much.(Experimental data and mathematical model.) 3a. Fibrous packed bed with 0.3 mm dia. fiber, any depth. (Experimental data and mathematical model.) 3b. Same as 3a except 0.1 mm dia. fibers. 3c. Same as 3a except 0.05 mm dia. fibers. 4. Gas-atomized spray.(Experimental data from large Venturis, orifices, and rod- type units, plus mathemtical model.) 5. Mobile bed with 1 to 3 stages of fluidized hollow plastic spheres. (Experimental data from pilot plant and large-scale power plant scrubbers.) 18 ------- BIBLIOGRAPHY Calvert, S., "Engineering Design of Fine Particle Scrubbers," APCA Journal, 24.: 929-934, 1974. Calvert, S., "How to Choose a Particulate Scrubber," Chemical Engineering, August 29, 1977. Calvert, S., "Scrubbing," Chapter 6 in "Air Pollution," 3rd ed., Volume IV, Arthur Stern, editor, 1977. Calvert, S., J. Goldshmid, D. Leith, and D. Metha, "Scrubber Handbook," NTIS PB 213-016, August 1972. Calvert, S. and S. Gandhi, "Improved Design Method for F/C Scrubbing," paper presented at the Second EPA Fine Particle Scrubber Symposium, May 2-3, 1977, New Orleans, NTIS PB 273-828. Calvert, S., S. Yung, H. Barbarika, G. Monahan, L. Sparks, and D. Harmon, "A.P.T. Field Evaluation of Fine Particle Scrub- ber," paper presented at the Second EPA Fine Particle Scrubber Symposium, May 2-3, 1977, New Orleans, NTIS PB 273-828. Yung, S., H. Barbarika, and S. Calvert, "Pressure Loss in Venturi Scrubbers," APCA Journal, 27_: 348-351, 1977. Yung, S., S. Calvert, and H. Barbarika, "Venturi Scrubber Per- formance Model," NTIS PB 271-515, August 1977. 19 ------- TECHNICAL REPORT DATA (Please read Instructions on the reverse before completing) 1. REPORT NO. EPA-600/8-78-005b 2. 3. RECIPIENT'S ACCESSION NO. 4. TITLE ANDSUBTITLE Particulate Control Highlights: Performance and Design Model for Scrubbers 5. REPORT DATE June 1978 6. PERFORMING ORGANIZATION CODE 7. AUTHORIS) 8. PERFORMING ORGANIZATION REPORT NO. S. Yung and S. Calvert 9. PERFORMING ORGANIZATION NAME AND ADDRESS A. P.T., Inc. 4901 Morena Boulevard, Suite 402 San Diego, California 92117 10. PROGRAM ELEMENT NO. EHE624 11. CONTRACT/GRANT NO. 68-02-2190 12. SPONSORING AGENCY NAME AND ADDRESS EPA, Office of Research and Development Industrial Environmental Research Laboratory Research Triangle Park, NC 27711 13. TYPE OF REPORT AND PERIOD Task Final: 9/77-4/78 COVERED 14. SPONSORING AGENCY CODE EPA/600/13 15. SUPPLEMENTARY NOTESTjjjRL-RTP project officer is Dennis C. Drehmel, Mail Drop 61, 919/541-2925. EPA-600/8-77-020a, -020b, and -020c are earlier reports in this series. is. ABSTRACT The report gives a capsule summary of the best available design models for wet scrubbers and their application to fine particulate control. Details of the models are reported in the Scrubber Handbook and other EPA publications listed in the bibliography. When EPA initiated its Wet Scrubber Systems Study in 1970, the state-of-the-art was largely empirical. Each application was considered to be a special case which could only be dealt with on the basis of long and specific exper- ience. Engineering design was based on a primative, cut-and-try approach and often resulted in an expensive overdesign to cover the wide range of uncertainty. There was also very little scrubber performance information available. In the Wet Scrubber Systems Study all available information concerning wet scrubber theory and practice was reviewed and evaluated. The best available engineering design methods were evaluated and, where necessary, new or revised methods were developed to provide as sound a basis as possible for predicting performance. The Scrubber Handbook, published in 1972, resulted from this study. 17. KEY WORDS AND DOCUMENT ANALYSIS DESCRIPTORS b.IDENTIFIERS/OPEN ENDED TERMS c. COSATI Field/Group Pollution Dust Scrubbers Gas Scrubbing Mathematical Models Pollution Control Stationary Sources Particulate 13B 11G 07A 13H 12A 18. DISTRIBUTION STATEMENT Unlimited 19. SECURITY CLASS (ThisReport) Unclassified 21. NO. OF PAGES 25 20. SECURITY CLASS (Thispage) Unclassified 22. PRICE EPA Form 2220-1 (9-73) 20 ------- |