Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Including internal mixing or stirring means
Reexamination Certificate
2000-06-16
2002-01-15
Knode, Marian C. (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Including internal mixing or stirring means
C422S239000, C422S143000, C261S114200
Reexamination Certificate
active
06338828
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a distribution apparatus and a quench zone mixing apparatus (or device) that may include the distribution apparatus, both of which are suitable for efficiently mixing and redistributing reactants across the horizontal cross-section of a vertical reaction vessel.
2. Discussion of Related Art
Many catalytic processes are carried out in reactors that contain a series of separated catalytic beds. Frequently, in such processes, quench zone mixing devices are advantageously located to provide rapid and efficient mixing of the fluid streams being processed in the reactor with a cooler fluid stream supplied from an external source. Consequently, the temperature of the process stream entering the successive catalyst beds can be controlled. One skilled in the art will appreciate that the better the mixing of the reactant streams, the better the temperature and reaction can be controlled. As a result, the overall performance of the reactor will be better.
Examples of quench zone mixing devices include U.S. Pat. Nos. 3,353,924, 3,480,407, 3,541,000, 4,669,890, and 5,152,967. Some of these devices are complicated and are prone to plugging. Others need a relatively large vertical space to ensure the desired degree of mixing. Still others create an undesirably high pressure drop. Consequently, there is a continuing need for a suitable quench zone mixing device that can efficiently mix fluid streams in a low vertical space with an acceptably low pressure drop.
Typically, the quench zone mixing devices are located above an associated fluid distribution system; for example, a horizontally disposed distribution plate or tray. The distribution plate collects the fluid (vapor and liquid), uniformly distributes it across the plate and discharges the fluid on to the catalyst bed. Such distribution tray may contain a number of “bubble cap” assemblies which may be disposed over one or more openings in the distribution tray. The bubble cap provides intimate mixing of the vapor and liquid before the mixed phase fluid is distributed across the catalyst bed.
Examples of distribution trays include U.S. Pat. Nos. 2,778,621, 3,218,249, 4,960,571, 4,836,989, 5,045,247, 5,158,714 and 5,403,561. Although one or more of these designs may be acceptable, there is still room for improvement, particularly in providing a uniform distribution of vapor and liquid phases into contact with the catalyst in the reactor vessel.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a distribution apparatus that includes a redistribution tray (also referred to herein as a “redistribution plate”). It is another object of the invention to provide a quench zone mixing apparatus (also referred to herein as the “quench zone mixing device”) that includes a swirl chamber, a rough distribution network disposed underneath the swirl chamber, and, preferably, a distribution apparatus disposed underneath the rough distribution network. It is to be understood that the distribution apparatus can be associated with the quench zone mixing device or can be used separately from the quench zone mixing device; for example, at the top of the reactor vessel.
The distribution apparatus includes a redistribution plate (also referred to herein as a “plate”) having a plurality of apertures and a plurality of bubble caps with at least some of the bubble caps associated with at least some of the apertures. In one embodiment, a plurality of drip trays are substantially horizontally disposed underneath the redistribution plate. At least some of the drip trays are associated with at least some of the bubble caps. The drip trays receive fluids exiting the associated bubble caps and distribute them through at least one discharge port provided on the bottom of the drip tray. In another embodiment, the drip trays have at least two discharge ports to multiply the fluid drip stream received from the bubble cap and symmetrically distribute the fluid across the catalyst surface.
Instead of the drip trays, at least one deflector baffle, and preferably a plurality of deflector baffles, may be placed below the redistribution tray. Preferably at least some of the deflector baffles are associated with at least some of the bubble caps.
As noted above, the quench zone mixing apparatus includes a swirl chamber. The swirl chamber is adapted to receive fluids from upstream in the reactor (such as those exiting a catalyst bed located above the swirl chamber). Preferably, the swirl chamber is substantially cylindrical. The swirl chamber includes a wall disposed between a ceiling and a floor. The wall has a plurality of openings, such as inlet openings, that provide a means of fluid communication into the swirl chamber. The floor surrounds an orifice, which provides a means for fluid to exit the swirl chamber. Preferably, a weir is provided about the periphery of the orifice. Baffles are located inside the swirl chamber which stabilize the vapor and liquid phase vortices, reduce the required overall height of the swirl chamber, provide a wide operating range for vapor and liquid throughput, and promote turbulence/mixing within each of the fluid phases. At least some of the openings have a baffle associated with the openings.
The rough distribution network is disposed beneath the swirl chamber to receive fluids from the swirl chamber. The rough distribution network includes a splash plate and radially outwardly extending channels. The splash plate is adapted to collect fluids from the swirl chamber and radially outwardly distribute them through the channels. Preferably, the channels include side walls with spaced apart notches to allow fluid to exit the channels. Fluids exiting the channels fall onto a distribution apparatus disposed beneath the rough distribution network.
Preferably, the distribution apparatus includes the redistribution plate substantially horizontally mounted below the rough distribution network and the swirl chamber. The redistribution plate extends substantially across the entire cross-section of the vessel to separate an upper section of the vessel from a lower section. The redistribution plate comprises a plurality of apertures and a plurality of bubble caps associated with the apertures of the redistribution plate. More preferably, a bubble cap is associated with each aperture to provide the sole means of fluid flow through the plate.
The bubble caps include a riser and a spaced apart cap. The riser has a top and a bottom and the riser is secured near the bottom to the redistribution plate. A passageway is defined between the top and bottom and provides a means of fluid communication across the redistribution plate. Preferably, the cap has a plurality of spaced apart slots to allow the flow of fluids through the cap and into the annulus defined by the cap and the riser.
In a preferred embodiment, the ceiling of the swirl chamber is closed. A liquid collection tray, preferably frusto-conically shaped, surrounds the swirl chamber and is sloped so that the one end adjacent the inlet openings is lower than the other end adjacent to the vessel wall. Fluid exiting the preceding catalyst bed falls onto the liquid collection tray or onto the ceiling of the swirl chamber where it is directed onto the liquid collection tray and through the inlet openings. Baffles are located inside the swirl chamber adjacent the openings and in communication with the openings to receive and direct incoming fluid circumferentially about the swirl chamber. In this preferred embodiment, the orifice is centrally located and provides the sole means for fluid to exit the swirl chamber. Additional baffles, i.e., wall baffles and internal baffles (the latter located on the floor of the swirl chamber), may also be included.
In another preferred embodiment, a quench fluid system is provided to introduce quench fluid into or above the swirl chamber. The quench fluid system may include a feed pipe in communication with a concentric manifold that surrounds the swirl chamber. A plurality of q
Bingham F. Emmet
Jacobs Garry E.
Kuskie Robert W.
Nelson Douglas E.
Stupin Steven W.
Doroshenk Alexa A.
Fish & Associates, LLP
Fluor Corporation
Knode Marian C.
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