Patent Application
20070297285
The present invention encompasses the discovery of an energy efficient device for initial co-current upflow or downflow distribution of two fluids into a reactor or mixing vessel. The specific design is particularly applicable for efficient mixing of viscous fluids. This is applicable to large scale two phase mixing and/or reacting systems or for co-introduction of reactants into a vessel utilizing a single distributor. Some examples of two phase mixed and reacting systems include: the cold acid (sulfuric or hydrofluoric acid) alkylation of olefins with iso-paraffins and metals extraction utilizing an immiscible organic and aqueous phase. One of the fluids could be catalytic in nature, such as a slurry phase catalyst. Additionally, the distributor can be used for initial combination of individual reactants at the outlet of the distributor. For these and other similar applications the processes require uniform distribution of both fluids over a large area. The combination of this two-phase distributor described herein in combination with static mixing devices for the purposes of efficient mixing on a large scale is envisioned. As compared to WO 02/092207 the distributor of the present invention is contemplated to be used with a packed bed of material, structured packing or another static mixer device to provide additional mixing for liquid/liquid or gas/liquid contact. The invention eliminates much of the complexity involved with three dimensional scaling and allows for a cost effective and energy efficient means of mixing.
The distributor herein stems from the same basis as U.S. Pat. No. 6,616,327 which incorporated by reference herein in its entirety, in which fractal patterns are utilized. To increase the number of distribution points per square foot of distributor, the fractal pattern is repeated on the next layer of distribution. Each layer of distribution is typically a formed, shaped or cut out plate. For a fractal distributor, in which each fractal plate contains enough fractal elements to expand its number of inlets, each into 6 fractal branches, feeding 6 separate outlets and maintains the same geometric arrangement on a plate by plate basis, the number of distribution drip points goes up as nm where n is the number of fundamental fractal divisions per plate and m is the number of plates, such that four fractal plates provide a total of 1296 drip points.
For planar geometry the smallest building block of the fractals stems from linear branching starting at the node located in the centroid of the overall shape. The shortest path length from the starting node to the outlet nodes is a straight line. When these fundamental building blocks are combined to form more complex fractal distributor (with the restriction that all outlet nodes are equidistant apart) the paths between the central node (or centroid of the overall shape) to the outlet nodes becomes more complex in order to provide the same path length or fractal geometry. This particular fractal patterning is more fully described in U.S. Pat. No. 6,616,317, previously incorporated by reference.
Although is it recognized that to hold to an exact fractal pattern is not practical, the point in striving for this geometric arrangement is to obtain the same flow path length to each drip point. This allows for a robust distributor design as every flow path is hydraulically equivalent. From a distribution standpoint this allows for large variation in overall flowrates and the capability to handle changes in fluid properties (such as viscosity) while maintaining equid distribution per point.
Therefore the object of the present invention is to provide a single fractal distributor which distributes two fluids independently up until they are combined at the final outlets. This is allowed by providing independent fractal flow channels up until reaching the final drip points of the last layer of fractal plates.
For general construction of fractal plates the reader is referred to U.S. Pat. No. 6,661,317. One section of fractal plates shaped as a pie wedge is shown in
Referring now to the figures, a preferred embodiment includes three plates: 1) an acid (or highly viscous fluid) predistribution plate; 2) a final acid distribution plate and 3) a hydrocarbon distribution plate. Both feeds enter the vessel from above and then must be connected to their respective inlets. In FIG., 1 the acid predistribution plate 100 is shown from the top. The acid inlet is shown at 101. The holes 102 are for bolts that hold the plates together.
Referring now to
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The problem to get the hydrocarbon inlet piping to the hydrocarbon inlets 301 without the piping interfering with final outlet drip pattern is solved by bring the hydrocarbon inlet piping in overhead along with the acid inlet piping. The hydrocarbon inlet piping, after splitting into 6 overhead pipes, is then passed through spaces 308 at the edge of the plate assemble section and connected to the inlet without passing near or through final drip points 304.
Referring now to
Although three sets of plates are used to illustrate the invention, the first two plates only provide for acid distribution. Only one is used for hydrocarbon distribution. One plate could have been used for the acid distribution. It is contemplated that two plates is the lowest number of plates for mixing two different liquids and many plates in some applications.
