Liquid purification or separation – With repair or assembling means
Reexamination Certificate
1999-12-22
2002-10-29
Cintins, Ivars (Department: 1724)
Liquid purification or separation
With repair or assembling means
C210S284000, C210S289000
Reexamination Certificate
active
06471861
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to piping components for distribution and collection of fluids from grids supporting particulate material such as adsorbents or catalyst. The invention is specifically directed to fluid distributor-collector devices which are placed at several intermediate points in a cylindrical bed of solid material to allow the addition or withdrawal of a liquid stream at any of these several points.
2. Description of the Prior Art
Fluid-solids contacting apparatus are in widespread commercial use as reactors and as adsorption zones. These devices are normally cylindrical columns containing a cylindrical mass of the solid contact material. The solid contact material may be catalyst or solid adsorbent. The fluid flows through the cylindrical mass of solids along the major axis of the column and may flow from one end of the column to another or from one intermediate point in the column to another. To maximize the effectiveness of the intended operation, the fluid should have a uniform composition and flow rate at all points across the cross section of the column to establish a desired “plug flow”.
Pressure vessels that contain particulate material for contacting fluids such as gas or liquid process streams are standard features of the chemical and refining industries. In processes for the selective adsorption of components from a multi-component feed and in processes for multi-stage contacting of reactants with a catalyst, partitions commonly subdivide the mass of adsorbent or catalyst in the interior of the pressure vessel into different chambers. The chambers retain a series of adsorbent or catalyst beds comprising discrete particles which permit staged or multiple contacting operations within a single pressure vessel. Such arrangements are routinely used in processes for the simulated moving bed adsorption process. Some fluid-solids contacting columns, especially those used to simulate the movement of the bed of solids, have multiple fluid feed and withdrawal points located intermediate to the ends of the column. At these points it is desired to respectively disperse or collect fluid across the entire cross section of the column.
A simulated moving bed adsorbent process exemplifies a process that regularly uses multiple partitions in relatively large pressure vessels. U.S. Pat. No. 2,985,589, the contents of which are hereby incorporated by reference, describes the moving bed adsorbent process in detail. The process distributes and collects process streams from multiple chambers of adsorbent defined by internal partitions located within a pressure vessel and composed of distribution/collection grids. Periodic shifting of the input and effluent streams over the chambers simulates movement of the adsorbent and permits delivery or withdrawal of the streams with a desired concentration profile.
Delivering or withdrawing the streams requires flat distribution grids. Common arrangements dispose the grids in a vertically oriented pressure vessel having a vertical centerpipe within the vessel with the grids spaced apart vertically for horizontal fluid distribution. U.S. Pat. No. 4,378,292 shows a typical large-diameter grid arrangement. Each grid is in the form of a flat ring extending between the centerpipe and the vertical outer wall of the vessel and comprises a plurality of grid sectors or semi-annular segments that have an overall wedge shape. Beds of solid particles are located between the layers of fluid distributor grids. Grid sectors at each grid level are placed side by side to fill the annular area between the centerpipe and vessel wall.
The grids receive or collect fluid from a plurality of fluid distribution/collection manifolds located in or about the centerpipe at points intermediate the vertically adjacent layers of fluid distributor grids. Requirements for the relatively uniform collection and distribution of fluids from the grids results in the withdrawal or addition of fluid from a central portion of each grid sector. Thus piping is needed to extend from the grid sector through the bed of adsorbent material to the manifold. The term “grid piping” refers to the plurality of fluid distribution/collection pipes that extend from each fluid distributor grid sector to a manifold located above the fluid distributor grid.
Most processes need provision for periodic replacement of the particulate material in the beds which requires disassembly and re-assembly of the grids. To facilitate installation, removal, and maintenance of the grid sectors and the grid piping one or more connections are placed along the length of the grid pipes for installation and removal of the piping. Common practice uses bolted flanges to provide these detachable connections. Installing and maintaining the piping in the numerous grid sections and having the piping connections present in the adsorbent poses a number of disadvantages for the process. For example a differential pressure of as little as 2 psi or less across the relatively flat grids can structurally damage the partitions by causing permanent deformation. Structural damage to the partitions has the potential to create leaks in associated connections of the distribution/collection piping. Such leaks typically contaminate the zones created by the partition and reduce the effectiveness of the separation, particularly with respect to the purity and/or yield of the products recovered from the process.
The flanges must therefore resist leakage at the piping connections. The size and bulk of the necessary flanges detract from process operations. The volume of the flanges over and above the volume of an equivalent length of pipe displaces additional catalyst or adsorbent from the bed. Any loss of particulate material reduces the effective inventory of the bed for the process application.
More importantly, the enlarged profile of the flange relative to the piping disrupts fluid flow through the particulate material immediately upstream and downstream of the protruding flange elements. Adsorbent material downstream of the flange is particularly sensitive to the blocked flow of fluid and results in a “shadowing” effect that renders some portion of the downstream absorbent ineffective for separation and susceptible to extended retention times. The extended retention times further disrupt the desired plug flow of the fluid and can raise the level of impurities in the final products. The degradation of process performance from shadowing usually has the greatest impact when separating viscous materials such as fructose and glucose where the relatively high solids content liquids results being quite viscous as compared to petroleum derived streams.
A well known type of piping connection uses a series of machined grooves on the ends of pipes that are connected by bridging links that have complementary grooves for engaging the grooves on the pipe ends. A sleeve or other retaining means is used to hold the link members against the pipes and the cooperating grooves in engagement. Different forms of these types of connections can be seen in U.S. Pat. No. 5,152,556, U.S. Pat. No. 5,265,917, U.S. Pat. No. 5,131,632, and U.S. Pat. No. 4,159,132. These types of connections have not been used in applications that route piping through beds of particulate material.
Accordingly, it is an object of this invention to improve the utilization and performance of adsorbent or catalyst in partitioned beds of particulate material separated by distribution/collection grids.
It is a further object of this invention to improve the operation of simulated moving bed adsorption process by reducing flow disruption and adsorbent displacement resulting from the presence of grid piping.
BRIEF DESCRIPTION OF THE INVENTION
It has now been discovered that low profile pipe connections can significantly improve process performance or substantially reduce reload time for partitioned beds of particulate material separated by distribution/collection grids. This invention is a multi-sectored grid arrangement that connects piping
Burgard Jeffrey E.
Schulz Gary A.
Cintins Ivars
Paschall James C.
Tolomei John G.
UOP LLC
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