Patent Description:
Falling film apparatus are in widespread industrial use as heat exchangers as e.g. disclosed in <CIT>. They are useful as evaporators, for performing separations, for performing crystallizations, as well as in other applications. Falling film apparatus have multiple vertical tubes supported at each end by a tube sheet. The tubes are contained in a shell, through which a heat exchange fluid is circulated into contact with the vertical tubes to provide or remove heat from the tubes. A liquid to be so treated is passed downwardly through the interior of the tubes, where the liquid is heated or cooled, as the case may be.

Optimal operation of a falling film apparatus depends on forming a film of the liquid on all interior surfaces of the tubes. The liquid should wet all internal surfaces of each tube and in addition wet those surfaces uniformly and continuously throughout the operation of the device. Non-uniform distribution of the liquid can cause various problems, including reduced operating efficiencies. Unwanted reactions and fouling are common problems caused by improper liquid distribution in falling film apparatus.

For any liquid, there exists a theoretical minimum flow rate per tube that is necessary to maintain a film on the interior tube surfaces. Practically, it is necessary to operate at several times this theoretical minimum flow rate per tube. This constrains the range of operating rates that can be employed. Using higher flow rates promotes uniform wetting, but creates thicker films and can result in less efficient operation. Fluid passing through the device often must be recirculated one or more times to achieve the desired result, thereby increasing operating costs. Residence times are also increased, which can be problematic when, for example, the liquid is sensitive to time-temperature effects. Design improvements which allow a falling film apparatus to operate at flow rates closer to the theoretical minimum flow rate would be desirable.

This invention is in one aspect a falling film apparatus as defined in claim <NUM>.

The second aspect which concerns the associated process is defined in claim <NUM>.

Turning to <FIG>, the invention includes tube sheet <NUM> and hollow tube <NUM>. Hollow tube <NUM> has associated tube insert <NUM>. In the cross-sectional view of a simplified apparatus shown in <FIG>, only a single hollow tube <NUM> is present. More typically, multiple hollow tubes (and associated tube inserts <NUM>) will be present. Each hollow tube <NUM> has open top end <NUM> and open bottom end <NUM>. Each hollow tube <NUM> defines a fluid path from above to below tube sheet <NUM> through an opening in tube sheet <NUM> (and to below a lower tube sheet such as lower tube sheet <NUM> as shown in <FIG>). An opening in tube sheet <NUM> accommodates each hollow tube <NUM>. Tube sheet <NUM> is sealed around each hollow tube <NUM> such that a fluid flowing from above to below tube sheet <NUM> must pass through a hollow tube <NUM>.

Hollow tubes <NUM> typically are cylindrical, with a circular cross-section, although hollow tubes <NUM> can assume other cross-sectional shapes if desired.

Hollow tubes <NUM> are vertically oriented, by which is it meant hollow tubes are oriented within <NUM> degrees of vertical, preferably within <NUM> degree of vertical.

Tube inserts <NUM> each are located at the top end of the associated hollow tube <NUM>. As shown in <FIG>, tube inserts <NUM> have an upper section <NUM> that resides above the upper surface of upper tube sheet <NUM> and a lower section <NUM> that extends into the associated hollow tube <NUM>. Sidewall <NUM> defines an interior flow path through each tube insert <NUM>.

Lower section <NUM> has outer cross-sectional dimensions equal to or smaller than the inside cross-sectional dimension of the associated hollow tube <NUM>, so lower section <NUM> can extend into associated hollow tube <NUM>. Lower section <NUM> may (as shown in <FIG>) or may not extend below the level of tube sheet <NUM>. In <FIG> and <FIG>, dotted lines <NUM> indicate various possible locations of tube sheet <NUM> when tube inserts <NUM> are in place in the falling film apparatus.

Tube inserts <NUM> each have one or more process fluid openings <NUM> in upper section <NUM> for admitting a process fluid into the tube insert. "Process fluid" means any fluid or mixture of fluids (which may further contain a dispersed solid phase) that is passed through tube inserts <NUM> and hollow tubes <NUM>, including a starting feed fluid introduced into tube inserts <NUM> and hollow tubes <NUM> as well as evaporated materials, reaction product or other products produced within hollow tubes. The process fluid contains at least one component that is liquid under the conditions that exist at the locations of circumferential ribs <NUM> of each tube insert <NUM>. The composition of the process fluid may change as it travels through tube insert <NUM> and/or hollow tube <NUM>.

In one embodiment, the process fluid opening is simply the open upper end of tube insert <NUM>. In other embodiments, multiple process fluid openings <NUM> are provided in the wall of upper section <NUM> of tube insert <NUM>, as shown in each of <FIG>, <FIG>, <FIG>, <FIG>. The size and shape of the process fluid openings may vary. Elliptical process fluid openings are shown in <FIG>, being arranged about the circumference of upper section <NUM> of tube insert <NUM>, and displaced longitudinally from the top edge of tube insert <NUM>. In the embodiments shown in <FIG>, <FIG>, process fluid openings <NUM> are rectangular slots oriented longitudinally about the circumference of upper section <NUM> of tube insert <NUM>, and are displaced longitudinally from the top edge of tube insert <NUM>. In the embodiments shown in <FIG>, process fluid openings <NUM> take the form of triangular (<FIG>) or rectangular (<FIG>) notches arranged about the circumference of the top edge of tube insert <NUM>.

In the embodiment shown in <FIG>, process fluid opening <NUM> takes the form of helical slots that, as shown, are displaced longitudinally from the top edge of tube insert <NUM>. Although only a single process fluid opening <NUM> is shown in <FIG>, multiple helical slots preferably are present and are arranged about the circumference of the top edge of tube insert <NUM> so as to provide overlap between fluid streams entering tube insert <NUM> from the multiple helical slots. Fluid feed openings <NUM> can have other shapes as may be convenient or beneficial, such as squares, circles, rhombuses, ellipses, semi-circles, trapezoids, other polygons, or other arbitrary shape. The number of process fluid openings <NUM> provided in the wall of upper section <NUM> is not critical to the invention and may vary widely, such as from <NUM> to <NUM> or more. Similarly, the size of the multiple process fluid openings may vary considerably as may be necessary or desirable, and the multiple process fluid openings may or may not all be the same size.

Tube inserts <NUM> also each have an open bottom end <NUM> (<FIG>, <FIG>, <FIG>, <FIG>) in lower section <NUM> for discharging process fluids from each tube insert <NUM> into the associated hollow tube <NUM>. Tube inserts <NUM> may be chamfered at open bottom end <NUM>, as shown in <FIG>, to produce a smooth transition from tube insert <NUM> into hollow tube <NUM>.

Tube inserts <NUM> have one or more circumferential ribs <NUM> residing on the interior surface of tube inserts <NUM>, below the process fluid opening(s). Circumferential ribs <NUM> may reside in upper section <NUM> of tube insert <NUM> (as is the case in <FIG> and for circumferential ribs 22A, 22C and 22D in <FIG>, respectively), in lower section <NUM> (as is the case in <FIG>, <FIG>, and for circumferential ribs 22B and 22E in <FIG>, respectively) and/or at the boundary between upper section <NUM> and lower section <NUM> (i.e., a the level of upper tube sheet <NUM>). As shown in <FIG>, circumferential ribs may reside in both upper section <NUM> and lower section <NUM>.

Any arbitrary number of circumferential ribs may be provided. For example, the number of circumferential ribs is up to <NUM>, up to <NUM> or up to <NUM>, and only a single circumferential rib may be present.

By "circumferential", it is meant that the rib extends entirely around the interior wall of tube insert <NUM>, forming a circle (if oriented perpendicular to longitudinal central axis <NUM> of tube insert <NUM>, as shown in <FIG>, <FIG>, <FIG>) or an ellipse (if oriented non-perpendicularly to longitudinal central axis <NUM> of tube insert <NUM>, as illustrated by circumferential ribs 22A, 22C and 22D in <FIG>. As shown in <FIG>, multiple circumferential ribs may be oriented at different angles to longitudinal central axis <NUM> if desired. In <FIG>, circumferential ribs 22A, 22C and 22D are oriented non-perpendicularly to longitudinal central axis <NUM> whereas circumferential ribs 22B and 22E are oriented perpendicularly to longitudinal central axis <NUM>. All circumferential ribs <NUM> may be oriented at the same angle to longitudinal central axis <NUM>.

Each circumferential rib <NUM> projects radially inward (i.e., toward the central longitudinal axis) from the interior surface of tube insert <NUM>. The radial width WRib (see <FIG>) of each circumferential rib in some embodiments is at least <NUM>, and in some embodiments is at least <NUM> or at least <NUM>. The radial width WRib may be, for example, as great as one-eighth the inner diameter IDTI of tube insert <NUM> (IDTI/<NUM>), and in particular embodiments may be up to IDTI/<NUM> or IDTI/<NUM>.

Each circumferential rib <NUM> has a longitudinal width δRib (<FIG>). δRib in some embodiments is at least <NUM>, and in some embodiments is at least <NUM> or at least <NUM>. δRib may be, for example, up to <NUM>, up to <NUM>, up to <NUM> or up to <NUM>.

The inward edges <NUM> of circumferential ribs <NUM> may be curved, and when curved the inward edges <NUM> may have a radius of curvature RRib such that RRib ≤ δRib/<NUM>. When RRib = δRib/<NUM> the inward edge <NUM> will have a semi-circular cross-section. RRib may be ≤ δRib/<NUM>, ≤ δRib/<NUM>, or ≤ δRib/<NUM> and in some embodiments RRib > δRib/<NUM>, preferably > δRib/<NUM> or > δRib/<NUM>.

Circumferential ribs <NUM> may be integral with sidewall <NUM> of tube insert <NUM>, or may be a separately-produced member that is affixed into position within tube insert <NUM>. If separately-produced, circumferential ribs <NUM> may be affixed to sidewall <NUM> by, for example, welding or gluing, such as weld or adhesive <NUM> (<FIG>), or mechanically through the use of various fasteners, and hangers such as hanger apparatus <NUM> and supports <NUM> (<FIG>). Circumferential slots for receiving circumferential ribs <NUM> may be provided in sidewall <NUM>.

Integral circumferential ribs <NUM> may be produced by machining the interior of sidewall <NUM> of precursor tube 12A to remove wall material above and below the location of each circumferential rib <NUM>, as shown in <FIG>. Tube insert <NUM> is fabricated from a precursor tube 12A, which has a wall thickness Y greater than sidewall thickness X of tube insert <NUM> made therefrom. Shaded portions 40A of sidewall <NUM> in <FIG> are removed by machining to produce tube insert <NUM> having a sidewall thickness X and circumferential rib <NUM>. The combined thickness of the wall and rib may be equal to original wall thickness Y.

The interior surface of sidewall <NUM> may be of uniform interior diameter (except for the ribs). In embodiments such as shown in <FIG>, the interior surface of sidewall <NUM> in upper section <NUM> of tube insert <NUM> tapers outwardly in a region 25A starting below fluid process openings <NUM> to above ribs <NUM>, thereby increasing the interior diameter of tube insert <NUM> through that region 25A of upper section <NUM>. Such a design further facilitates smooth annular flow of the process fluids towards circumferential ribs <NUM>.

In operation, a process fluid is introduced onto the upper surface of tube sheet <NUM> and upon reaching a certain height (such as indicated by liquid interface <NUM> in <FIG> and <FIG>) spills over into upper section <NUM> of tube inserts <NUM> through process fluid openings <NUM>. Upon entering tube inserts <NUM>, the process fluids are driven downward within the associated tube inserts <NUM> past circumferential ribs <NUM> by gravitational and/or differential pressure forces, continuing downward through lower section <NUM> of tube inserts <NUM>, then out of tube inserts <NUM> through open bottom ends <NUM> and into hollow tubes <NUM>. Circumferential ribs <NUM> capture the momentum of the falling process fluid to distribute the fluid evenly about the circumference of tube insert <NUM>, forming a uniform film without dry spots. The uniform film is maintained as the process fluid passes through open bottom ends <NUM> and into and through associated hollow tubes <NUM>.

Tube inserts <NUM> may further include one or more features such as flow deflectors that produce a tangential flow of process fluid entering the tube insert. The process fluid openings may be machined to produce a tangential flow of process fluid entering the tube insert.

Turning to <FIG>, falling film apparatus <NUM> includes outer shell <NUM>, which defines a vessel having an enclosed interior volume. Upper tube sheet <NUM> and lower tube sheet <NUM> partition the enclosed interior volume into upper portion <NUM> residing above upper tube sheet <NUM>, middle portion <NUM> residing between upper tube sheet <NUM> and lower tube sheet <NUM>, and lower portion <NUM> residing below lower tube sheet <NUM>. Hollow tubes <NUM> define fluid paths from upper portion <NUM> through middle portion <NUM> to lower portion <NUM> of the enclosed interior volume. An opening in upper tube sheet <NUM> and an opening in lower tube sheet <NUM> accommodates each hollow tube <NUM>. Upper tube sheet <NUM> and lower tube sheet <NUM> each are sealed around each hollow tube <NUM> such that a fluid flowing from upper portion <NUM> to below lower portion <NUM> must pass through a hollow tube <NUM>.

Falling film heat apparatus <NUM> further includes at least one process fluid inlet port <NUM> for introducing a process fluid into upper portion <NUM> of the interior space enclosed by shell <NUM>. Multiple process fluid inlet ports <NUM> may be provided. Falling film apparatus <NUM> further includes at least one process fluid outlet port <NUM> for removing process fluid(s) from lower portion <NUM> of the interior space enclosed by shell <NUM>. Multiple process fluid outlet ports <NUM> may be provided. In the embodiment shown in <FIG>, a separate gas outlet port <NUM> is provided for removing vapor from lower portion <NUM> of the space enclosed by shell <NUM>.

Falling film apparatus <NUM> further includes at least one heat exchange fluid inlet port <NUM> for introducing a heat exchange fluid into interior space <NUM> and at least one heat exchange fluid outlet port <NUM> for removing heat exchange fluid from interior space <NUM>.

In addition to the foregoing features, falling film apparatus <NUM> may include various optional components. A distributor may be provided to distribute process fluid onto upper tube sheet <NUM>. A wide variety of distribution systems are available to ensure the uniformity of the liquid level on the top tube sheet. One type of distributor is a flat-bottomed container installed above upper tube sheet <NUM>. The container has holes that allow the process fluid to flow onto upper tube sheet <NUM> between tube inserts <NUM>. A spray distribution system sprays droplets of process fluid over upper tube sheet <NUM> and/or a flat-bottomed container installed above upper tube sheet <NUM>. Other useful distributors include, for example, any of those described in <CIT>, <CIT> and <CIT>, and <CIT>. Other optional components include various valves, pumps, automated process control devices, and the like.

In operation, a process fluid is introduced into upper portion <NUM> via one or more inlet ports <NUM>. The process fluid pools on the upper surface of upper tube sheet <NUM> and upon reaching a certain height (reference numeral <NUM> in <FIG> and <FIG>) spills over into upper section <NUM> of tube inserts <NUM> through process fluid openings <NUM>. Upon entering tube inserts <NUM>, the process fluid falls under force of gravity and/or applied pressure downwardly past circumferential ribs <NUM>, through lower section <NUM> of tube inserts <NUM>, then out of tube inserts <NUM> through open bottom ends <NUM> and into and through hollow tubes <NUM>, ultimately passing into lower portion <NUM> of heat exchange apparatus <NUM>. As described before, the falling process fluid upon passing circumferential ribs <NUM> becomes distributed evenly about the circumference of tube insert <NUM>, forming a uniform film without dry spots. The uniform film is maintained as the process fluid passes through open bottom ends <NUM> and into and through associated hollow tubes <NUM>.

In heat exchange operations, hollow tubes <NUM> are maintained at a different temperature than the process fluid introduced via feed inlet port(s) <NUM>, and thus heat is exchanged between hollow tubes <NUM> and the process fluid. The hollow tube temperature may be higher or lower than that of the incoming process fluid. The hollow tube temperature typically is higher for operations such as evaporations, pasteurizations and performing chemical reactions, and lower for operations such as crystallizations.

Heat is supplied or removed from hollow tubes <NUM> via a heat exchange fluid that is introduced into middle portion <NUM> via heat exchange fluid inlet port <NUM>. The heat exchange fluid circulates within interior space <NUM>, between upper tube sheet <NUM> and lower tube sheet <NUM> and in contact with hollow tubes <NUM>, heating or cooling hollow tubes <NUM> (as the case may be), and is withdrawn through heat exchange fluid outlet port <NUM>. The heat exchange fluid may be a liquid and/or a gas. Some or all of the heat exchange fluid may undergo a phase change within the vessel; steam, for example, may partially or entirely condense within the vessel. Heat exchange fluids are selected at least partially with the desired operating temperatures in mind. Examples of other heat exchange fluids include liquid water, air, nitrogen, argon, helium, liquid and/or gaseous halocarbons (including hydrohalocarbons), silicone fluids, ethylene glycol, propylene glycol and other alkylene glycols and polyalkylene glycols, various alkylated aromatic compounds, various polyester compounds, and the like.

In some embodiments, the falling film apparatus of the invention is used to perform evaporations. In such embodiments, the process fluid is a single-component liquid, which is to be evaporated within hollow tubes <NUM> or, more typically, a multicomponent fluid containing at least one component that is to be separated from at least one other component by fractional distillation within hollow tubes <NUM>. Evaporations typically produce one or more gaseous products representing component(s) of the process fluid that become evaporated within hollow tubes <NUM>, and one or more liquid products which are components of the process fluid that pass through hollow tubes <NUM> without evaporating. It is generally preferred to establish a flow of gases downward through hollow tubes <NUM> so that gaseous products are removed from the bottom of hollow tubes <NUM>; however it is within the scope of the invention to remove gaseous products from the top of hollow tubes <NUM>.

The falling film apparatus shown in <FIG> is particularly adapted for performing evaporations. The annular film of process fluid flowing downwardly into and through hollow tubes <NUM> is heated in hollow tubes <NUM>, and at least a portion of one or more components of the process is volatilized to form a gas.

In the embodiment shown in <FIG>, both the volatilized (gaseous) and non-volatilized components of the process fluid flow into lower portion <NUM> of the vessel, where they are separated. In the embodiment shown, volatilized component(s) are removed from lower portion <NUM> via line <NUM>, through which they are transferred to optional gas-liquid separator <NUM> to remove entrained non-volatilized material from the gaseous products. The gaseous products are then recovered via line <NUM>.

Non-volatilized component(s) of the process fluid are removed from lower portion <NUM> of the vessel via outlet port <NUM> and line <NUM>. In the optional arrangement shown, non-volatilized component(s) removed via line <NUM> are combined with additional quantities of non-volatilized component(s) removed from gas-liquid separator <NUM> via line <NUM>. A non-volatilized product stream is withdrawn via recovery line <NUM>.

All or a portion of the non-volatilized components recovered from falling film apparatus <NUM> may be recycled back into falling film apparatus <NUM> if desired, as is the case, for example, of incomplete evaporation of volatile components of the process fluid. In <FIG>, for example, a recycle stream is taken via line <NUM>, recombined with fresh process fluid, and the mixture fed into upper portion <NUM> of enclosed interior space <NUM> via line <NUM> and inlet port <NUM>.

An important advantage of this invention is that annular films of liquid components of the process fluid can be formed without dry spots on all internal surfaces of tube inserts <NUM> and hollow tubes <NUM>, even at low liquid flow rates. Lower liquid flow rates produce thinner films. Thinner films allow for faster and more uniform heating or cooling of the process fluid and, in the case of evaporations, more complete removal of volatile components from the process fluid. As a result, less material needs to be recycled. Recycled material experiences a more severe thermal history than material processed in a single pass, as the recycled material is exposed to the elevated temperatures for a much longer time period. When the recycled material contains heat-sensitive components, the ability to reduce recycling, thereby reducing exposure times to elevated temperatures, is often a significant advantage.

The ability to produce annular films without dry spots at low flow rates also extends the range of conditions at which the falling film apparatus can be operated. For example, it may be desirable or necessary to operate at relatively low flow rates at certain times, such as during start-ups or shutdowns, without fouling the apparatus or producing non-prime material. The falling film apparatus of the invention permits operation over a wide range of flow rates.

Flow rates though a hollow tube apparatus can be expressed in terms of a minimum wetting rate Γmin, which is a function of the contact angle θ (between the entering process fluid and the tube or insert), and the surface tension σ, viscosity µ, gravitational constant g and density ρ of the process fluid, as follows: <MAT>.

Previous falling film apparatus with tube inserts typically operate at a flow rate of <NUM> or more times Γmin; they do not produce uniform annular films at lower flow rates. By contrast, the falling film apparatus of this invention operates well at flow rates as low as <NUM>Γmin or even lower, and also operate well at much greater flow rates. Thus, in some embodiment of the invention, the falling film apparatus of the invention is operated at a flow rate of <NUM>Γmin to <NUM>Γmin, <NUM>Γmin to <NUM>Γmin or <NUM> to <NUM>Γmin.

The falling film apparatus of the invention is useful for performing many types of separations, including producing concentrated foods such as concentrated fruit juices and evaporated and/or condensed milk, manufacturing alcoholic beverages such as whiskeys, as well as in many chemical and/or petrochemical processes.

Among the many chemical separations for which the falling film apparatus is useful is the separation of a crude isocyanate mixture produced by phosgenating a mixture of methylene dianiline with higher polymethylene polyanilines. In such a separation, diphenyl methylene diisocyanate (MDI) is separated from higher polymethylene polyphenylene polyisocyanates (having three or more phenyl isocyanate groups) by passing the crude mixture through the falling film apparatus operated at a tube temperature sufficient to volatilize the MDI but not the higher polymethylene polyphenylene polyisocyanates. This produces an MDI-rich vapor stream that may contain, for example, at least <NUM>% by weight MDI, and a liquid stream of polymethylene polyphenylene polyisocyanates that is, relative to the starting crude mixture, enriched in polymethylene polyphenylene polyisocyanate and depleted in MDI.

A hollow stainless steel tube having an inner diameter of <NUM> is fitted in a tube sheet positioned in the bottom surface of a container. A tube insert having an outer diameter of <NUM> and wall thickness of <NUM> is inserted into the hollow tube such that an upper section resides above the level of the tube sheet and a lower section resides within the hollow tube below the level of the tube sheet. Eight process fluid openings in the form of longitudinal slots <NUM> in width are spaced evenly about the circumference of the upper section of the tube insert. Associated with each of the process fluid openings is a flow deflector positioned at an angle of about <NUM> degrees to the open face of the slot. The flow deflectors produce a tangential flow entry of the process fluid into the tube insert. The interior surface of the tube insert below the process fluid openings is smooth and of a constant diameter.

A fluid having (at the temperature of the experiment) a density of <NUM>/m<NUM>, a viscosity of <NUM> cP, a surface tension of <NUM> mN/m and an advancing contact angle with stainless steel of <NUM> degrees is poured into the container to create a flow rate of <NUM>/h, yielding a wetting rate Γ of <NUM>/m-s. The minimum wetting rate Γmin for this fluid is <NUM>/m-s, as calculated according to Equation <NUM> above. The operating ratio Γ/Γmin is <NUM>. Under these conditions, the liquid forms rivulets on the inner walls of the tube insert and does not uniformly wet the walls. A uniform annular film is produced only when the flow rate is increased to produce an operating ratio Γ/Γmin of greater than <NUM>.

Comparative Sample A is repeated, except this time the tube insert has <NUM> circumferential ribs in the inner wall beneath the process fluid openings. RRib is <NUM>, WRib is <NUM>, and δRib is <NUM>. A uniform film forms as the process fluid passes downwardly past the circumferential ribs, wetting all interior surfaces of the tube insert, at the operating ratio Γ/Γmin = <NUM>.

Claim 1:
A falling film apparatus comprising:
(a) an outer shell (<NUM>) enclosing an interior volume,
(b) upper (<NUM>) and lower (<NUM>) tube sheets partitioning the interior volume into separate upper (<NUM>), middle (<NUM>) and lower (<NUM>) chambers,
(c) one or more vertically oriented hollow tubes (<NUM>) having open top and bottom ends, the hollow tubes each defining a fluid path from the upper chamber (<NUM>) to the lower chamber (<NUM>),
(d) for each at least one vertically oriented hollow tube (<NUM>), an associated tube insert (<NUM>) located at the top end of the associated hollow tube, the tube insert (<NUM>) comprising a hollow member having (i) an upper section (<NUM>) residing above the upper tube sheet (<NUM>), (ii) a lower section extending into the associated hollow tube (<NUM>), (iii) one or more process fluid openings (<NUM>) in the upper section (<NUM>) for admitting a process fluid into the tube insert (<NUM>), (iv) an open bottom end for transferring a thin film of the process fluid from an interior surface of the tube insert (<NUM>) onto an interior surface of the associated hollow tube (<NUM>); and (v) one or more circumferential ribs (<NUM>) residing on the interior surface of the tube insert (<NUM>) below the one or more process fluid opening(s) (<NUM>);
(e) at least one process fluid inlet port (<NUM>) for introducing a process liquid into the upper chamber (<NUM>) and into contact with an upper surface of the upper tube sheet (<NUM>),
(f) at least one process fluid outlet port (<NUM>) for removing at least treated process fluid from the lower chamber (<NUM>);
(g) at least one heat exchange fluid inlet port (<NUM>) for introducing a heat exchange fluid into the middle chamber (<NUM>); and
(h) at least one heat exchange fluid outlet port (<NUM>) for removing the heat exchange fluid from the middle chamber (<NUM>).