CO2 Solutions Inc.
`Exhibit 2009
`Akermin, Inc. v. CO2 Solutions Inc.
`IPR2015-00880
`Page 1 of 12
`
`

`
`
`
`T A J‘
`
`
`OPERATIONS
`
`Third Edition
`
`Robert E. Treybal
`The Late Professor of Chemical Engineering
`
`University of Rhode Island
`
`
`MCGRAW-HILL
`C LAS SIC
`TEXTB®K
`REIS s U
`'§l/I?‘-\ , ‘ //
`
`
`
`McGraw-Hill, Inc.
`New York St. Louis San Francisco Auckland Bogota
`Caracas Lisbon London Madrid Mexico City Milan
`Montreal New Delhi San Juan Singapore
`
`Page 2 of 12
`
`

`
`it
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`
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`-;,."*7.
`
`MASS-TRANSFER OPERATIONS
`
`Copyright © 1980, 1968, 1955 by McGraw-Hill Book Company, Inc.
`Reissued 1987 by the McGraw-Hill Book Company, Inc. All rights
`reserved. Printed inithe United States of America. Except as permitted
`under the United States Copyright Act of 1976, no part of this
`publication may be reproduced or distributed in any form or by any
`means, or stored in a data base or retrieval system, without the prior
`written permission of the publisher.
`
`ISBN D-D?-lJl:.5l?l=-U
`
`18192021 BKMBKM998765
`
`Library of Congress Cataloging in Publication Data
`
`Treybal, Robert Ewald, date
`Mass—transfer operations.
`
`(McGraw—I-Iill chemical engineering series)
`Includes bibliographical references and index.
`1. Chemical engineering.
`2. Mass transfer.
`I. Title.
`1980
`TP156.M3T7
`ISBN 0-07-065176—O _
`
`660.2’8422
`
`78-27876
`
`This book was set in Times Roman by Science Typographers, Inc.
`The editors were Julienne V. Brown and Madelaine Eichberg;
`the production supervisor was Charles Hess.
`New drawings were done by Santype Ltd.
`Arcata Graphics/
`
`Page 3 of 12
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`

`
`this becomes less important when a chemical reaction eccurs, as in the
`[54],
`case or” the sulfur dioxide absorbers. Multistage countercurrent eifects can be
`obtained by using several venturis {3]. The device is also used for removing dust
`particles from gases [l2].
`
`ta’?
`
`WET'l”ED-JWALL TGWEES
`
`A thin film of liquid running down the inside of a vertical pipe, with gas flowing
`either cocurrently or countercurrently, constitutes a wetted-wall tower. Such
`devices have been used for theoretical studies of mass transfer, as described in
`Chap. 3, because the interfacial surface between the phases is readily kept under
`control and is measurable. industrially, they have been used as absorbersqfor
`hydrochloric acid, where absorption is accompanied by a very large evolution of
`heat [63].'ln this case the wetted-wall tower is surrounded with rapidly flowing
`cooling water. Multitube devices have also been used for distillation, where the
`liquid film is generated at the top by partial condensation of the rising vapor.
`Gas-pressure drop in these towers is probably lower than in any other gas-liquid
`contacting device, for a given set of operating conditions.
`
`SPRAY TOWERS AND SPRAY CHAMBERS
`
`The liquid can be sprayed into a gas stream by means of a nozzle which
`disperses the liquid into a‘ fine spray of drops. The flow may be countercurrent,
`as in vertical
`towers with the liquid sprayed downward, or parallel, as in
`horizontal spray chambers (see Chap. 7). These devices have the advantage of
`low pressure drop for the gas but also have a number of disadvantages. There is
`a relatively high pumping cost for the liquid, owing to the pressure drop through
`the spray nozzle. The tendency for entrainment of liquid by the gas leaving is
`considerable, and mist eliminators will almost always be necessary. Unless the
`diameter/length ratio is very small, the gas will be fairly thoroughly mixed by
`the spray and full advantage of countercurrent flow cannot be taken. Ordinarily,
`however, the diameter/length ratio cannot be made very small since then the
`spray would quickly reach the walls of the tower and become ineffective as a
`spray.
`
`PACKED TOWERS
`
`Packed towers, used for continuous contact of liquid and gas in both counter-
`current and cocurrent flow, are vertical columns which have been filled with
`packing or devices of large surface, as, in Fig. 6.27. The liquid is distributed over,
`and trickles down through, the packed bed, exposing a large surface to contact
`the gas.
`
`Page 4 of 12
`
`

`
`1% MASS-TRANSFER OPERATIONS
`
`AGas out
`
`Liquid distributor
`
`Packing resfrainer
`
`Shell
`
`Random packing
`
`i
`
`Liquid
`re-distributor
`
`Packing support
`
`-=e———Gos in
`
`—————> Liquid out
`
`Figure 6.27 Packed tower. '
`
`Page 5 of 12
`
`

`
`Paeking
`
`The tower packing, or fill, should offer the following characteristics:
`
`1. Provide for large interfacial surface between liquid and gas. The surface of
`the packing per unit volume of packed space ap should be large but not in a
`microscopic sense. Lumps of coke, for example, have a large surface thanks
`to their porous structure, but most of this would be covered by the trickling
`film of liquid. The specific packing surfaceap in any event is almost always
`larger than the interfacial liquid-gas surface.
`T
`2. Possess desirable fluid-flow characteristics. This ordinarily means that the
`fractional void volume 5, or fraction of empty space, in the packed bed
`should be large. The packing must permit passage of large volumes of fluid
`through small tower cross sections without loading or flooding (see below)
`and with low pressure drop for the A gas. Furthermore, gas-pressure drop
`should be largely the result of skin friction if possible, since this ismore
`effective than form drag in promoting high values of the mass-transfer
`coefficients (see Wetted-wall towers).
`. Be chemically inert to fluids being processed.
`. Have structural strength to permit easy handling and installation.
`. Represent low cost.
`
`Lhuhb)
`
`Packings are of two major types, random and regular.
`
`Random Packings V
`Random packings are simply dumped into the tower during installation and
`allowed to fall at random. In the past such readily available materials as broken
`stone, gravel, or lumps of coke were used, but although inexpensive, they are not
`desirable for reasons of small surface and poor fluid-flow characteristics. Ran-
`dom packings most frequently used at present are manufactured, and -the A
`common types are shown in Fig. 6.28. Raschig rings are hollow cylinders, as
`shown, of diameters ranging from 6 to l()() m (;’,- to 4 in) or more. They may be
`made of chemical stoneware orporcelain, which are useful in Contact with most
`liquids except alkalies and hydrofluoric acid; of carbon, which is useful except
`in strongly oxidizing atmospheres; of metals; or of plastics. Plastics must be
`especially carefully chosen, since they may deteriorate rapidly with certain
`organic solvents and with oxygen-bearing gases at only slightly elevated temper-
`atures. Thin-walled metal and plastic packings offer the advantage of lightness
`in weight, but in setting floor—loading limits it should be anticipated that the
`tower may inadvertently fill with liquid. Lessing rings and others with internal
`partitions are less frequently used.-The saddle-shaped packings, lBerl andlntalox
`saddles, and variants of them, are available in sizes from 6 to 75 m G to 3 in),
`made of chemical stoneware or plastic. Pall iings, also known as Flexirings,
`Cascade rings, and as a variant, Hy-Pak, are available in metal and plastic.
`
`Page 6 of 12
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`

`
`199 MASS-TRANSFER OPERATIONS
`
`
`
`A
`
`(£7)
`
`(b)
`
`‘
`
`V
`
`(f)
`
`Figure 6.28 Some random tower packings: (a) Raschig rings, (b) Lessing ring, (c) partition ring, (d)
`Berl saddle (courtesy of Maurice A. Knight), (e) Intalox saddle (Chemical Processing Products Division,
`Norton Co.), (j) Tellerette (Ceilcote Conypany, Inc.), and (g) pall ring (Chemical Processing Products
`Division, Norton ‘Co.).
`A
`'
`
`of plastic. Generally the random packings offer larger specific surface (and
`larger gas-pressure drop) in the smaller sizes, but they cost less per unit volume
`in the larger sizes. As a rough guide, packing sizes of 25 mm or larger are
`ordinarily used for gas rates of 0.25 m3/s (w 500 ft3/min), 50 mm or larger for
`gas rates of l m3/s (2000 ft3/min). During installation the packings are poured
`into the tower to fall at random, and in order to prevent breakage of ceramic or
`carbon paekings, the tower may first be filled with water to reduce the velocity
`of fall.
`’
`
`Regular Packings
`
`These are of great variety. The counterflow trays already considered are a form
`of regularpaclcing, as are the arrangements of Fig. 6.29. The regular packings
`offer the advantages of low pressure drop for the gas and greater possible fluid
`flow rates, usually at
`the expense of more costly installation than random
`packing. Stacked Raschig rings are economically practical only in very large
`sizes. There are several modifications of the expanded metal packings [105].
`Wood grids, or hurdles, are inexpensive and frequently used where large void
`volumes are required, as with tar-bearing gases from coke ovens or liquids
`carrying suspended solid particles. Knitted or otherwise woven wire screen,
`rolled as a fabric into cylinders (Nee-Kloss) or other metal gauzelike arrange-
`ments (Koch-Sulzer, Hyperfil, and Goodloe packings) provide a large interfacial
`surface of contacted liquid and gas and a very low gas-pressure drop, especially
`useful for vacuum distillation [10, 77]. Static mixers were originally designed as
`
`Page 7 of 12
`
`

`
`
`
`(c)
`
`.
`
`.
`
`(d).
`
`.
`
`Figure 6.29 Regular, or stacked, packings: (a) Raschig rings, stacked staggered (top view), (b)
`double spiral ring (Chemical Processing Products Division, Norton Co.),
`(c) section through
`expanded-metal-lath packing, (d) wood grids.
`
`but in general they consist of metal eggcratelike devices installed in a pipe to
`cause a multitude of splits of cocurrently flowing fluids into left- and right-hand
`streams, breaking each stream down into increasingly smaller streams [85].
`These devices have been shown to be useful for countercurrent gas-liquid
`contact [I21], with good mass-transfer characteristics at low gas-pressure drop.
`
`Tower Shells
`These may be of wood, metal, chemical stoneware, acidproof brick, glass,
`plastic, plastic- or glass—lined metal, or other material depending upon the
`corrosion conditions. For ease of’ construction and strength they are usually
`circular in cross section.
`
`Packing Supports
`
`An open space at the bottom of the tower is necessary for ensuring good
`distribution of the gas into the packing. Consequently the packing must be
`supported above the open space. The support must, of course, be sufficiently
`strong to carry the weight of a reasonable height of packing, and it must have
`ample free area to allow for flow of liquid and gas with a minimum of
`restriction. A bar grid, of the sort shown in Fig. 6.27, can be used [112], but
`specially designed supports which provide separate passageways for gas and
`liquid are preferred. Figure 6.30 shows one variety, whose free area for flow is of
`the order of 85 percent and which can be made in various modifications and of
`
`Page 8 of 12
`
`

`
`192 MASS-TRANSFER OPERATIONS
`
`
`
`Figure 6.30 Multibeam support plate. (Chemical Process Products Division, Norton Co.)
`
`many different materials including metals, expanded metals, ceramics, and
`plastics.
`’
`
`Liquid Distribution
`
`The importance of adequate initial distribution of theliquid at the top of the
`packing is indicated in Fig. 6.31. Dry packing is of course completely ineffective
`for mass transfer, and various devices are used for liquid distribution. Spray
`nozzles generally result in too much entrainment of liquid in the gas to be useful.
`The arrangement shown in Fig. 6.27 or a ring of perforated pipe can be used in
`small towers. For large diameters, a distributor of the type shown in Fig. 6.32
`can be used, and many other arrangements are available. It is generally consid-
`ered necessary to provide at least five points of introduction of liquid for each
`0.1 m2 (1 ftz) of tower cross section for large towers (d > 1.2 In = 4 ft) and a
`greater number for smaller diameters.
`‘
`'
`
`Random Packing Size and Liquid Redistribution
`
`In the case of random packings, the packing density, i.e., the number of packing
`. pieces per unit volume, is ordinarily less in the immediate vicinity of the tower
`
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`Page 9 of 12
`
`

`
`35%
`
`
`
`Figure 6.32 Weir-trough liquid distributor. (Chemicals Process Products Division, Norton Co.)
`
`walls, and this leads to a tendency of the liquid to segregate toward the walls
`and the gas to flow
`the center of the tower (channeling). This tendency is
`much less pronounced when the diameter of the individual packing pieces is
`smaller than at least one-eighth the tower diameter, but it is recommended that,
`if possible,
`the ratio c{,/ T = 1 : 15. Even so it is customary to provide for
`redistribution of the liquid at intervals varying from 3 to .10 times the tower
`diameter, but at least every 6 or 7 m. Knitted mesh packings placed under a
`packing support (Fig. 6.30) make good redistributors [41]. With proper attention
`to liquid distribution, packed towers are successfully built to diameters of 6 or
`'7 m or more.
`
`Packing Restrainers
`
`These are necessary when gas velocities are high, and they are generally
`desirable to guard against lifting of packing during a sudden gas surge. Heavy
`screens or bars may be used. For heavy ceramic packing, heavy bar plates
`resting freely on the top of the packing may be used. For plastics and other
`lightweight packings, the restrainer is attached to the tower shell.
`
`Entrainment Eliminators
`
`Especially at high gas velocities, the gas leaving the top of the packing may carry
`off droplets of liquid as a mist. This can be removed by mist eliminators,
`through which the ‘gas, must pass, installed above the liquid inlet. A layer of
`mesh (of wire, Teflon, polyethylene, or other material) especially knitted with 98
`to 99 percent voids, roughly 1% mm thick, will collect virtually all mist particles
`[18, 124]. Other
`types of elirninators include cyclones and venetian-blind
`arrangements [53]. A meter of dry random packing is very effective.
`
`Page 10 of 12
`
`

`
`194 MASS-TRANSFER OPERATIONS
`
`
`
`logAP/Z,pressuredrop/height
`
`
`
`
`
`
`
`log 6,’ superficial gas mass velocity
`
`Figure 6.33 Typical gas pressure
`drop for counterflow of liquid and
`gas in random packings.
`
`Countercurrent Flow of Liquid and Gas through Packing
`
`For most random packings, the pressure drop suffered by the gas is influenced
`by the gas and liquid flow rates in a manner similar to that shown in Fig. 6.33.
`The slope of the line for dry packing is usually in the range 1.8 to 2.0, indicating
`turbulent flow for most practical gas velocities.
`At a fixed gas velocity, the gas—pressure drop increases with increased liquid
`rate, principally becauseof the reduced free cross section available for flow of
`gas resulting from the presence of the liquid. In the region of Fig. 6.33 below A,
`‘the liquid holdup,
`i.e., the quantity of liquid contained in the packed bed, is
`reasonably constant with changing gas velocity, although it increases with liquid
`rate. In the region between A and B, the liquid holdup increases rapidly with gas
`rate, the free area for gas flow becomes smaller, and ‘the pressure drop rises more
`rapidly. This is known as loading. As the gas rate is increased to B at fixed liquid
`rate, one of a number of changes occurs: (1) a layer of liquid, through which the
`gas bubbles, may appear at the top of the packing;_(2) liquid may fill the tower,
`starting at the bottom or at any intermediate restriction suchas a packing
`support, so that there is a change from gas—continuous liquid—dispersed to
`liquidwcontinuous gas—dispersed (inversion); or (3) slugs of team may rise
`rapidly upward through the packing. At the same time, entrainment of liquid by
`the effluent gas increases rapidly, and the tower is flooded. The gas pressure drop
`then increases very rapidly. The change in conditions in the region A to B of
`Fig. 6.33 is gradual, and initial loading and flooding are frequently determined
`by the change in slope of the pressure-drop curves rather than through any
`visible effect. it is not practical to operate a tower in a flooded condition; most
`towers operate just helow, or in the lower part of, the loading region.
`
`Page 11 of 12
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`

`
`0.4
`
`0.2
`
`0.10
`0.08
`0.06
`
`0.04
`
`0.02
`
`0.01
`0.008
`0.006
`0.004
`
`0.002
`0.001
`
`5 ,1?
`‘L <5
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`2' S
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`FOR GAS=-LZQUED —f)PERAZ"lCBNS
`
`H1 (.511
`
`—r
`»
`§§L’“‘-
`l200
`800
`400
`
`.
`
`we
`
`3
`
`V
`Approximate
`/ flooding
`\
`9
`
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`I
`l
`I
`1 9211 1b1‘f/tl‘l2:6.37 x 10-3 51$?
`infll 0 _
`_3 N/m2
`gt
`-1.224 X 10
`-2?-
`
`\ V
`\
`
`1
`
`
`
`0.01
`
`0.02
`
`0.04
`
`0.1
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`0.2
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`0.4
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`1.0
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`A PC )1/2
`
`P1, “P0
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`2
`
`4
`
`10
`
`Figure 6.34 Flooding and pressure drop in random—packed towers. For SI units gc = 1, Cf from
`Table 6.3, and use J = 1. For G’ = lb/ft2- h, p = lb/ft3, 11,; = cP, gc = 4.18 X 108, Cf from Table
`6.3, and use J = 1.502. [Coordinatesof Eckert [38], Chemical Process Products Division, Norton Co.)
`
`Flooding and Loading
`
`Flooding conditions in random packings depend upon the method of packing
`(wet or dry) and settling of the packing [76]. The upper curve of Fig. 6.34
`correlates the flooding data for most random packings reasonably well. More
`specific data are in the handbooks [47] or are available from the manufacturers.
`The limit of loading cannot readily be correlated.
`Typically, absorbers and strippers are designed for gas-pressure drops of 200
`to 400 N /m2 per meter of packed depth (0.25 to 0.5 inH2O/ft), atmospheric-
`pressure fractionators from 400 to 600 (N/m2)/m, and vacuum stills for 8 to 40
`(N /m2)/In (0.01 to 0.05 inl-I20/ft) [38]. Values of C] which characterize the
`packings are given in Table 6.3 (these and other values in Table 6.3 change with
`changes in manufacturing procedures, so that the manufacturers should be
`consulted before completing final designs). Flooding velocities for regular or
`stacked, packings will generally be considerably greater
`than for
`random
`packing.
`
`Page 12 of 12