Methods and devices for falling film reactors with integrated heat exchange

Disclosed is a method of performing a reaction involving a gaseous reactant stream and a falling film liquid reactant stream by providing a reactor comprising a first multicellular extruded body oriented with its cells extending in parallel in a vertically downward direction from a first end of the body to a second end, the body having a first plurality of cells open at both ends of the body and a second plurality of said cells closed at one or both ends of the body, the second plurality of cells being arranged in one or more groups of contiguous cells and cooperating to define at least in part at least one fluidic passage extending through the body; and further flowing a liquid reactant film down inner surfaces of the first plurality of cells while flowing a gaseous reactant stream up or down the centers of the first plurality of cells while flowing a first heat exchange fluid through the at least one fluidic passage. Various alternative devices for performing the method are also disclosed.

RELATED APPLICATIONS

The present application is related to U.S. Provisional Application Ser. No. 60/921,053, filed 31 Mar. 2007 entitled, “Honeycomb Continuous Flow Reactor” and to U.S. Provisional application 61/018,119 filed 31 Dec. 2007 entitled, “Devices and Methods for Honeycomb Continuous Flow Reactors”.

PRIORITY

This application claims priority to European Patent Application number EP08305041.9 filed Feb. 29, 2008 titled, “Methods and Devices For Falling Film Reactors With Integrated Heat Exchange”.

SUMMARY

According to one aspect of the invention, a method is disclosed of performing a reaction involving a gaseous reactant stream and a falling film liquid reactant stream by providing a reactor comprising a first multicellular extruded body oriented with its cells extending in parallel in a vertically downward direction from a first end of the body to a second end, the body having a first plurality of cells open at both ends of the body and a second plurality of said cells closed at one or both ends of the body, the second plurality of cells being arranged in one or more groups of contiguous cells and cooperating to define at least in part at least one fluidic passage extending through the body; and further flowing a liquid reactant film down inner surfaces of the first plurality of cells while flowing a gaseous reactant stream up or down the centers of the first plurality of cells while flowing a first heat exchange fluid through the at least one fluidic passage.

According to another aspect of the invention, a reactor useful for reacting a gaseous reactant stream with a falling film liquid reactant stream is disclosed. The has a first multicellular extruded body oriented with its cells extending in parallel in a vertically downward direction from a first end of the body to a second end. The extruded body has a first plurality of cells open at both ends of the body and a second plurality of said cells closed at one or both ends of the body and the second plurality of cells is arranged in one or more groups of contiguous cells and defines at least in part at least one fluidic passage extending through the body. The reactor further is provided with a fluid source structured and arranged so as to be able to distribute fluid to the first plurality of cells at the first end of the extruded body; a gas source positioned either above or below the extruded body structured and arranged so as to be able to flow a gas through the first plurality of cells; and a heat exchange fluid source connected to said at least one fluidic passage structured and arranged so as to be able to flow a heat exchange fluid therethrough.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to a methods and devices for falling film reactions. InFIG. 1is shown a plan view of a reactor component12useful in the devices and methods of the present invention. The reactor component12comprises a multicellular extruded body20, one embodiment of which is represented inFIG. 1. The body20has a plurality of cells extending in parallel in a direction from one end of the body to the other, with the cells seen end-on inFIG. 1. The cells include a first plurality of cells22open at both ends of the body and a second plurality of cells24closed at one or both ends of the body, in this embodiment by one or more plugs26or by a more or less continuous plugging material26disposed at or near the end of the body and at least partly within the channels of the second plurality of cells24. The second plurality of cells24(the closed cells) are positioned in one or more groups of contiguous cells, one group in this case, and cooperate to help define a fluidic passage28extending through the body20. The passage28may follow a serpentine path up and down along the cells24, in the general direction shown by arrowed28, which will represent both the passage and its path. The passage or its path28may extend laterally perpendicular to the cells24only at or near the ends32,34of the body20, where walls between the cells24are shortened or ported or otherwise passed or breached to allow fluid communication between the cells24.

Such shortened walls between the cells24are shown in the cross sections ofFIGS. 3 and 4, allowing the passage or path28to connect extend laterally perpendicular to the cells24at or near the of the body20. As may be seen inFIG. 3, the path28may follow a single cell up and down in the direction along the cells24. Alternatively, the path28may follow multiple successive respective groups of two or more cells in parallel, in the direction along the cells24, as shown inFIG. 4, in which the path follows two cells in parallel.

In another embodiment of the reactor component ofFIGS. 1 and 2, the path is not serpentine only in the direction along the cells as shown inFIG. 2, but also in the plane perpendicular to the cells, as shown in the plan view ofFIG. 5. The plurality of closed cells24in the plan view ofFIG. 5is arranged in a generally serpentine path in the plane perpendicular to the cells24and22. The fluid path28is thus serpentine at a relatively higher frequency in the direction in and out of the plane ofFIG. 5, and at a relatively lower frequency within the plane of the figure. This doubly serpentine path structure allows for high total path volume and long total path length while maintaining a large surface area between the path and the open cells22, and allows for small total package size for the reactor12.

The serpentine arrangement of closed cells in the plane perpendicular to the cells, the arrangement visible inFIG. 5, is not the only possible arrangement; other arrangements are possible or even desirable, depending on the application. It may be desirable, however, regardless of the shape of the path within the plane ofFIG. 1orFIG. 5, the plane perpendicular to the direction of the cells within the extruded body20, that the majority of the path28be only one cell wide. This results in an easily manufactured fluidic path capable of having a very high surface to volume ratio. It may likewise be preferable that the open cells22positioned between rows of the path28be arranged in groups only one cell wide, as inFIG. 5. This allows for a fluid path through the open cells that has also has a very high surface to volume ratio.

Additional cells of the closed cells24, in a grouping25of more than one cell in width, if desired, may be plugged around the entry and exit ports30of the pathway, as shown inFIGS. 1 and 5. These additional plugged cells can provide support for an O-ring seal or a fired-frit seal or polymer adhesive seal or any other desirable sealing system for providing a fluidic connection to the path28, and generally would not form a part of the passage or path28. One embodiment is shown inFIG. 6, in which access tubes36have been sealed to two groupings25of plugged cells.

The extruded body or honeycomb20is desirably formed of an extruded glass, glass-ceramic, or ceramic material for durability and chemical inertness. Alumina ceramic is generally presently preferred as having good strength, good inertness, and higher thermal conductivity than glass and some ceramics. Other higher thermal conductivity materials may also be employed. The multicellular body desirably has a cell density of at least 200 cells per square inch. Higher densities can lead to higher heat exchange performance devices. Bodies having 300 or more, or even 450 or more cells per square inch may be of potential interest for forming high performance devices.

FIG. 7is a cross-sectional view of the main components of one embodiment of a reactor10of the present invention comprising an extruded multicellular body or honeycomb, showing fluidic connections to the extruded body according to one embodiment of the present invention. In the embodiment ofFIG. 7, a fluid housing40supports the extruded body via seals42. The housing40may comprise a single unit enclosing the extruded body, or the middle portion40C may optionally be omitted, such that the housing comprises two parts40A and40B. According to the presently preferred embodiments of the invention, a reactant fluid passage or path48for liquid film reactants and gaseous reactants is formed through the open channels22(shown inFIGS. 1 and 5) in cooperation with the housing40. Path28in the body20is accessed via fluid conduits64through fluidic couplers46, and is utilized for heat exchange fluid or alternatively a reaction that acts as a desired heat source or sink. Fluid conduits64pass through openings61in the housing40, in which openings61a seal44is employed.

FIG. 8is an exploded perspective view of a reactor component12comprising an extruded multicellular body or honeycomb20, showing fluidic couplers46arranged for coupling to input and output ports30at the side of the extruded body20. Fluidic couplers46include a fluid coupler body50having raised concentric rings52surrounding a fluid passage54. When assembled, an elastomeric O-ring56is retained by the raised rings52in compression against a flat surface58formed on the side of the body20. The large number of wall structures within the extruded body20provides sufficient support for a robust compression seal against the flat surface58. Alternative sealing methods are possible, including fired-frit seals, polymer adhesive seals, and any such as may be suitable for the intended application.

A reactor component12such as the one in the embodiment ofFIG. 8allows for one presently preferred alternative configuration of a reactor10, shown inFIG. 9, which is a cross-sectional view of the main components of another embodiment of a reactor10of the present invention. The reactor10ofFIG. 9comprises an extruded multicellular body or honeycomb20and includes side-port fluidic connections to the extruded body20. Advantages over the embodiment ofFIG. 8in include the absence of seals44, and absence of any seal (such as seals44or fluidic couplers46) directly between the two fluid paths28,48. Seal materials may thus be optimized for the fluid of each path independently, and seal failures will not result in fluids from the two paths28,48intermixing.

A reactor for reacting a gaseous reactant stream with a falling film liquid reactant stream requires some method or means of forming a thin falling film on the relevant surface(s) of the reactor. According to an embodiment of the devices and methods of the present invention, the liquid reactant is delivered, such as by one or more liquid distribution tubes64, as shown inFIG. 10. The liquid reactant is flowed or dropped onto the surface of the plugs or continuous plugging material26, or in other words, on the surface27above the closed cells of the body20. As shown in the cross section ofFIG. 11, the liquid reactant stream62then follows the follows the path shown by the arrows62representing the liquid reactant stream62, flowing over the edges of the closed cells of the body20, and down the inside surfaces of the open cells. Gaseous reactant stream48flows in the center of the open cells, in countercurrent flow in this case, while a heat exchange fluid, which may also be in form of a reactant stream providing a reaction that acts as a source or sink of heat, is flowed along passage28. A liquid collector66collects the reactant liquid stream62.

A reactor10according to another embodiment of the present invention is shown in diagrammatic cross-section inFIG. 12. Two reactor components12A and12B, each comprising a respective extruded body20A,20B, are positioned one below the other with each body oriented with its cells extending in a vertically downward direction. Each body20A,20B has a first plurality of cells22open at both ends of the body and a second plurality of cells24closed at one or both ends of the body, as shown and discussed above with respect toFIGS. 1-6. As one alternative, open cells22may include in or on their interior surfaces, one or more catalytic materials, depending on the desired reactions to be performed. Note that some details shown inFIGS. 1-6are not shown or are not labeled inFIG. 12, for ease of representation.

As inFIGS. 1-6, the second plurality of cells24is arranged in one or more groups of contiguous cells and cooperates to define at least in part at least one fluidic passage28extending through the bodies20A,20B.

The reactor10ofFIG. 12further comprises a fluid source108arranged so as to be able to distribute reactive fluid stream62to the first plurality of cells22at the first end of the extruded body20A, through liquid distribution tube64. The delivered fluid steam62forms and annular ring of fluid63contained by the housing components of the reactor10described below. The annular fluid ring overflows onto the surface27of the continuous plugging material26A of the topmost body20A. From surface27, the fluid stream62overflows and forms a falling film down the interior of the open cells22of body20A.

Body20A is connected to body20B via a spacer82in the form of a short section of open-cell extruded body, in this embodiment having a cell size greater than that of bodies20A and20B. The liquid reactant stream accordingly flows downward from the open cells of body20A through the spacer along its internal surfaces and into the open cells of body20B.

The reactor10is provided with a gas source, connected via gas inlet tube78, so as to be able to flow a gas reactant stream48through the first plurality of cells22of both bodies20A and20B. Two heat exchange fluid sources112are connected to the respective fluidic passages28in bodies20A and20B so as to be able to flow a heat exchange fluid60therethrough. If desired, different fluids or at least different temperatures may be employed in the two bodies20A and20B.

As shown inFIG. 12, this embodiment uses side ports for access to the heat exchange fluid paths, via fluid coupler bodies50A and50B. End ports as inFIG. 7are an alternative.

Elements of the housing supporting bodies20A and20B include an end plate76at the top end of the reactor10through which a gas outlet tube80extends, allowing reactant gas stream48to exit the reactor, and an endplate in the form of a liquid collector66, though which gas inlet tube78extends, and through which liquid exit tubes68also extend. The various sections of the housing are formed by tube sections70, sealed to endplates76and66via O-rings72. Near the ends of bodies20A and20B, tube sections70are sealed via O-rings72to mounting rings74, which support the extruded bodies20A and20B, as well as spacer82, via seals42. Seals42may be elastomeric seals, epoxy-based or any appropriate material. In the embodiment ofFIG. 12, the top-most of seals42also contains the annular reservoir or ring of fluid63, and provides sealing for reaction fluid inlet tube64.

As shown in the perspective view ofFIG. 13, a reactor according to the present invention may include more than two multicellular extruded bodies such as bodies20A-D shown in the figure, each positioned below the first body20A, and each having, as disclosed inFIGS. 1-6, a respective plurality of open cells and a respective plurality of closed cells defining respectively at least one fluidic passage. The successive bodies20B-20D after the first body20A are positioned and arranged to receive one or both of the fluid reactant and the gaseous reactant flow from the respective next higher body. The heat exchange fluid flows60A-60D may be identical or may be individualized for each respective body20A-20D. The respective vertical lengths of each body20A-20D may also be chosen for the needs of the reaction to be performed: they need not be of uniform length, as illustrated by the shorter body20C.

It is desirable in the context of some falling filth reactions to prevent potential flame or explosion propagation within the reactor10, as flammable or explosive reactants may be used, or flammable or explosive products may be produced. Accordingly, as a further alternative within the context of the present invention, a flame barrier screen84may be provided, positioned at the ends of each body20A-20C, as shown inFIG. 14. the screens84may be mounted in various ways, such as by tension rings86,88that cooperate to keep the screens84tight. For purposes of reactor design and reaction engineering, along with the use of screens84, the length of the bodies20A-20C (that is, the length of the cells) and the width of the cells can be chosen to avoid any risk of out-of-control or explosive reactions. Again, lengths of extruded bodies may be different as needed for this optimization.

Alternatives for mounting or securing screens84include end face clamps90, such as shown at the top ofFIG. 19, where the screen is clamped over a part of the surface27at the top of the closed cells. End face clamping may also be achieved by use of a section of extruded body92with open cells, as shown at the bottom of the figure. Tension rings may be used in combination with end-face clamping, or may be omitted.

Two other alternatives for screen mounting are shown inFIG. 16, in which the top screen84is mounted in an adhesive94positioned on top of the closed cells. The bottom screen84is mounted by being incorporated into extended plugs26E. Tension rings are optional in either case, but likely superfluous in the case of extended plugs26E.

Flame barrier screens may also be used to aid in the distribution of reactant fluid62, as illustrated in the cross section ofFIG. 17. The top screen84helps wick or otherwise conduct reactant fluid62from the annular ring of fluid63to the tops of the closed cells in the body20, and the bottom screen, which may be curved as shown in the figure, helps wick or otherwise conduct the reactant fluid62from the bottoms of the open cells in body20to an annular receiving trough114. In this embodiment, the gaseous reactant flow48is desirably in the co-current direction, as shown, to assist the reactant fluid motion along and off from the screens84, although counter-current is possible.

As an alternative to flame barrier screens, porous body flame barriers96may be used, as shown in the cross-section ofFIG. 18. The porous body may also assist reactant fluid distribution as shown.

As shown in the description above, it will be understood that the present invention also provides a method of performing a reaction involving a gaseous reactant stream and a falling film liquid reactant stream. The method includes providing a reactor that comprises at least a first multicellular extruded body oriented with its cells extending in parallel in a vertically downward direction from a first end of the body to a second end. The body also has a first plurality of cells open at both ends of the body and a second plurality of said cells closed at one or both ends of the body, with the second plurality of cells arranged in one or more groups of contiguous cells cooperating to define at least in part one or more fluidic passage extending through the body. The one or more passages may have a serpentine path back and forth along cells of the second plurality, and the passage may connect laterally from cell to cell, within cells of the second plurality, at or near the ends of the body. The method further includes flowing a liquid reactant film down inner surfaces of the first plurality of cells while flowing a gaseous reactant stream up or down the centers of the first plurality of cells, while flowing at least a first heat exchange fluid through the at least one fluidic passage. The method may include providing a reactor having catalytic material in or on the inner surfaces of the first plurality of cells. The method may also include using multiple successive extruded bodies, optionally with different heat exchange feeds, and further optionally with varying reactant feeds for each.

In case pressure drop associated with flowing heat exchange fluid60along the path28through extruded bodies20of the present invention is too large for a particular reactor or reaction design, the flow path can be split into multiple parallel paths via an integrated manifold structure.FIGS. 19 and 20are plan views of reactor components12comprising an extruded multicellular body or honeycomb showing still another fluidic path28in a plane perpendicular to the cells22,24according to additional alternative embodiments of the present invention. As may be seen in the figures, these embodiments include manifolding or dividing of the fluid path within the fluidic passage28, such that the path28divides into parallel paths in the plane perpendicular to the cells.FIG. 21is cross-sectional view of channels24closed on one or both ends of an extruded body20, showing a method useful in the context of the present invention for manifolding or dividing fluid pathways, with two pathways dividing from one in a plane parallel to the cells24, and beginning within the extruded body20.

FIG. 22is a partial plan view of one end of an extruded body or honeycomb structure showing a method of or structure for manifolding having multiple parallel passages28beginning within the extruded body at an input port30on the one end of the extruded body.

FIG. 23is a partial side view of an extruded body or honeycomb structure showing another embodiment of multiple passages28beginning within the extruded body at an input port30on a wall or flat surface58on a side of the extruded body.

FIG. 24shows alternative ways of forming the heat exchange flow path28within the extruded bodies of the present invention. As one alternative, shown at the top of the body20ofFIG. 24, a contoured endcap may be employed, together with a gasket or other sealing material104. In this particular alternative, the walls of the cells of the body20require no modification. As a second alternative, shown at the bottom of the body20ofFIG. 24, a end plate102is provided with a contoured sealing material104, and the walls of the body are shortened to allow the sealing material104to grip the sides of the non-shortened walls, while allowing lateral passage from cell to cell.

FIGS. 25A-25Dshows alternative patterns for the plugs or continuous plug material26, corresponding to the pattern of the closed cells beneath. In each case, the fluid path defined within the closed cells may be serpentine along the direction of the cells. InFIG. 25B, the resulting path may be doubly serpentine, in25C the path in the plane perpendicular to the cells is parallel with manifolding within the body20, and in25D the path is parallel with manifolding, if any, external to the body20.