Fixed bed apparatus with support structure and methods for processing hydrocarbons using the same

Clay treatment apparatuses and methods for processing hydrocarbon products using clay treatment apparatuses are disclosed. In one exemplary embodiment, a clay treatment apparatus includes a vessel enclosing an interior space, an active clay material disposed within the interior space of the vessel, and a clay retention structure positioned above a bottom head portion of the vessel. The clay retention structure includes a wire mesh coupled with a perforated plate. In another exemplary embodiment, a method for processing a hydrocarbon product includes the steps of contacting the hydrocarbon product with an active clay material within an interior space of a vessel and passing the hydrocarbon product through a clay retention structure that includes a wire mesh and a perforated plate.

TECHNICAL FIELD

The technical field relates generally to hydrocarbon processing apparatuses and methods. More particularly, the technical field relates to fixed bed apparatuses that include support structures and methods for processing hydrocarbon products using the same.

BACKGROUND

Upgrading processes are typically catalytic reactions that remove unwanted molecules from petroleum distillates during the petroleum refining process. Oxidative demercaptization, which is also known as “sweetening” in view of the effect it has on the odor of the hydrocarbon liquid composition, is an important upgrading process. This process removes foul smelling, toxic, corrosive and unwanted sulfur-containing molecules, such as mercaptans, from the fuel stream by converting them into less harmful and odorous disulfides. It may also remove other unwanted trace polar compounds such as napthenates and phenols from the hydrocarbon liquid composition.

In the past various processes and catalysts have been used for sweetening hydrocarbon mixtures. However, today the Merox™ process, available from UOP LLC of Des Plaines, Ill., USA, has almost entirely replaced those older systems. The Merox process has been described in detail, and is well known to the person skilled in the art (see for example, U.S. Pat. No. 7,087,547; and “Merox Process for Kerosene/Jet Fuel Sweetening”—Process Technology and Equipment, (2003), published by UOP LLC).

As part of the Merox process, clay treatment (or clay filtration; e.g. using a clay treater) removes unwanted contaminants from a hydrocarbon liquid composition. Typically, the fuel is passed through a clay treater, where it comes into contact with the surface of the clay. Polar and ionic compounds, including surfactants, organometallic compounds, particulates, corrosion inhibitors, and other compounds within the fuel are adsorbed onto the surface of the clay and, thereby, removed from the fuel. Clay treatment is often used downstream of other upgrading units within the Merox process, in order to remove surfactants and other ionic species that may be introduced into the hydrocarbon composition during those processes.

Clay treatment units known in the art include concrete or clay that is used at the bottom head of the unit to support various functional components of the unit, including the “collector,” which is a plurality of cylindrical conduits that extend horizontally within the clay bed of the treatment unit. After fabrication at a fabrication site, clay treatment units are typically transported in a horizontal (as opposed to vertical, upright) fashion, and because of this, the fabricator cannot put the concrete inside the clay treatment unit at the fabrication site. Accordingly, it becomes necessary to install the clay treatment unit at the refinery site, and then to add the concrete to the bottom head thereof and install the collector. This installation process increases the amount of work required at the refinery site, as compared to putting the concrete and the collector in the unit at the fabrication site.

A current trend in the petroleum processing industry is that of “modularization,” wherein petroleum processing units are fabricated in modular form such that the amount of installation work necessary at the installation site is minimized. For example, much of the Merox processing system is currently available in modular form, which reduces the lead time between fabrication, installation, and ultimate operation-ready status. Due to the requirement of concrete addition after installation, the concept of modularization has proved time-consuming to implement as applied to clay treatment apparatuses.

Accordingly, it is desirable to provide improved clay treatment apparatuses for removing unwanted contaminants from a hydrocarbon liquid composition and methods employing the use of such apparatuses. Furthermore, it is desirable to provide such clay treatment apparatuses in modular form to reduce the on-site work required to install such apparatuses. Still further, it is desirable to provide such clay treatment apparatuses that do not require concrete as a collector support at the bottom head portion thereof. Furthermore, other desirable features and characteristics of the presently disclosed embodiments will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.

BRIEF SUMMARY

Clay treatment apparatuses and methods for processing hydrocarbon products using clay treatment apparatuses are disclosed. In one exemplary embodiment, a clay treatment apparatus includes a vessel enclosing an interior space, an active clay material disposed within the interior space of the vessel, and a clay retention structure positioned within a bottom head portion of the vessel. The clay retention structure includes a wire mesh coupled with a perforated plate.

In another exemplary embodiment, a method for processing a hydrocarbon product includes the steps of contacting the hydrocarbon product with an active clay material within an interior space of a vessel and passing the hydrocarbon product through a clay retention structure that includes a wire mesh and a perforated plate.

In yet another exemplary embodiment, a collector-less clay treatment apparatus includes a collector-less vessel including a vertically-oriented cylindrical body and enclosing an interior space, a distribution nozzle positioned below an upper head portion of the vessel, an Attapulgus active clay material disposed within the interior space of the vessel, and a circular clay retention structure having a diameter smaller than an inner diameter of the vessel and positioned within a bottom head portion of the vessel. The circular clay retention structure includes a wire mesh or profile wire, including openings sufficiently small to retain the active clay material above the clay retention structure, and is coupled with and abuttingly disposed against a perforated plate. The circular clay retention structure also includes a support ring abuttingly disposed against the perforated plate and the bottom head portion of the vessel. The apparatus further includes an outlet nozzle disposed below the clay retention structure.

DETAILED DESCRIPTION

The present disclosure is directed to various embodiments of clay treatment apparatuses for removing unwanted contaminants from a hydrocarbon liquid composition, and methods for processing hydrocarbon products employing the use of the same. The disclosed clay treatment apparatuses include a perforated plate and wire mesh support structure at the bottom head portion of the vessel. The wire mesh is provided with a small enough profile to prevent the clay particles from passing therethrough, and thus the need for a separate collector having such wire mesh is eliminated. Accordingly, the need for the traditional concrete collector support structure is also eliminated. In that sense, embodiments described herein may be referred to as “collector-less” with regard to the described apparatus or vessel. As used herein, the term “collector-less” describes an apparatus or vessel that excludes any collector structures as well as any collector support structures. The disclosed clay treatment apparatuses may thus be provided in modular form to reduce the on-site work required to install the apparatus.

For purposes of this disclosure, when the terms “upper”, “middle”, “top” or “lower” are used with respect to a clay treatment apparatus, these terms are to be understood as relative to each other, i.e. that withdrawal of a stream from the “top” of the unit is at a higher position than the stream withdrawn from a “lower” portion of the unit. When the term “middle” is used it implies that the “middle” section is somewhere between the “upper” and the “lower” section of the unit. However, when the terms “upper”, “middle” and “lower” have been used with respect to a clay treatment unit it should not be understood that such a unit is strictly divided into thirds by these terms.

As used herein, the term “head” may refer to one of a pair of caps on a cylindrically-shaped vessel. Generally, the head may be of a variety of shapes, such as hemispherical, ellipsoidal, torispherical, flat, diffuser-shaped, or conical. As used herein, the term “coupled” may mean the relationship between two items that are directly or indirectly, joined, fastened, associated, connected, or formed integrally together either by chemical or mechanical means, by processes including stamping, molding, or welding. Two items may be coupled by the use of a third component such as a mechanical fastener, e.g. a screw, a nail, a staple, or a rivet; an adhesive; or a solder. As used herein, the term “fluid” may mean a gas, a liquid, a suspension that may include one or more solid particles, or a combination thereof. A fluid may include or consist of one or more hydrocarbons. Furthermore, as used herein, a referenced dimension, such as a length, a width, or a height, may be the maximum such dimension for a structure, such as a body, a trough, or a plate.

As initially noted above, the clay treatment apparatuses of the present disclosure may be used in connection with a Merox process system. However, the disclosed apparatuses are not limited to such uses. Rather, it is expected that the disclosed apparatuses will find use wherever clay treatment is required or desirable for the removal of unwanted contaminants from a hydrocarbons stream. To serve as an exemplary, non-limiting illustration of one possible installation of such a clay treatment apparatus, a Merox process flow scheme is briefly introduced that includes a clay treatment apparatus in accordance with the present disclosure.

FIG. 1is a flow diagram illustrating a process for the upgrading of kerosene originating from crude petroleum. A crude petroleum starting material is first fed into a separation device in the form of a distillation column1, which fractionates the crude into mixtures of hydrocarbons having closely related boiling points. The exemplary distillation column is under atmospheric pressure; although reduced pressure may also be used, especially for the fractionation of heavy distillate compounds (i.e., those that boil at very high temperatures, e.g., above 500° C.). Kerosene, which is typically used in the production of jet fuel, for example, has an initial boiling point of approximately 147° C.

Kerosene is removed from the distillation column1and passed via a continuous pipeline2to a device for removing water contamination, for example, in the form of a water coalescer3. The water coalescer3generally includes a large diameter coalescer vessel that is commonly horizontally mounted. Inside the coalescer vessel is packed a coalescing media element, which is typically made up of closely woven steel wires, glass fiber strands, wood shavings and the like. The flow velocity of the fuel/water mixture is reduced on entering the coalescer vessel and, due to the low velocity and differences in the densities of the fuel and water, the fuel and water are segregated. As the mixture flows through the coalescer media, water coalesces into larger droplets and sinks to the bottom of the vessel from where it may be removed through a dip leg while the dry fuel passes through.

The fuel is then passed via a continuous pipeline4to a container where a caustic (i.e., alkaline) prewash is carried out in a caustic prewash vessel5. From the caustic prewash5the alkaline fuel is passed by a continuous pipeline6to a Merox reactor8. At some point, air at a suitable pressure and a Merox catalyst are added to the kerosene in order to convert any mercaptans in the fuel into disulfides. This is accomplished by injecting air (injection point not shown). In the alternative, the Merox reactor8may contain a solid bed Merox catalyst (for example, charcoal granules impregnated with catalyst). Additional details regarding operation of the reactor8may be found in U.S. Pat. No. 7,223,332.

After leaving the Merox reactor8, the now sweetened fuel is passed via pipeline9to a caustic settler10. The caustic settler10removes any caustic that has been carried through from the reactor8. Once the caustic has settled out it may be drained from the bottom of the settler10.

The sweetened kerosene is then passed from the settler10through a continuous pipeline11to a water wash vessel12, which is designed to wash residual caustic out of the sweetened kerosene. The water wash vessel12may have a separate inlet (not shown) for the introduction of water, and a separate outlet at the bottom of the vessel (also not shown) for removing residual water. The kerosene is then passed, for example via a continuous pipeline13, to a salt settler vessel14. The salt settler vessel14contains a bed of rock salt, which removes the entrained water from the sweetened kerosene, and an outlet at the bottom (not shown) for removing any extracted water.

In the process depicted, fuel exiting the salt settler vessel14via pipeline15is passed into a clay treater16. As previously described, the clay treater16may act as a polar trap and as a filter, removing oil-soluble substances such as metal ions and oxides, surfactants, organometallic compounds and particulate matter, which could prevent the fuel from satisfying the required product specifications. The clay treating is carried out at a temperature of from about 30 to about 60° C. (more typically from about 35 to about 45° C.) and, independently, at a pressure of from about 50 to about 300 psig. The provided clay treater16does not include any collector structure or any concrete collector support structure at a bottom head portion thereof, but rather makes use of a perforated plate/wire mesh support structure. As such, clay treater16is a collector-less apparatus. This support structure enables the clay treater16to be provided as a modular unit for the described Merox flow process, thus reducing installation time and saving installation costs. Greater detail regarding clay treater16is provided below in connection withFIGS. 2-4.

Finally, the sweetened kerosene is transferred by pipeline17to a storage tank19where it may remain until it leaves the refinery. At a point before the fuel leaves the refinery, it may be necessary to add chemical additives in order to satisfy the necessary product specifications/parameters. In the process shown, any additives are introduced from an additive supply18before the fuel enters the storage tank19. It will be appreciated that before and after the addition of additives it may be necessary to test the product specifications of the sweetened kerosene (not shown).

FIG. 2is a cross-sectional and elevational view of the exemplary collector-less clay treatment apparatus16shown inFIG. 1. As shown therein, clay treatment apparatus16includes a body or shell210forming a substantially cylindrical structure240with a first head270at one end244and a second head280at an opposing end246. The substantially cylindrical structure240may be orientated substantially vertically along a central axis201, as shown. Generally, the body210may contain an interior space212that may be filled with an active material216, which may be an adsorbent, such as a clay absorbent material. Any clay suitable for processing hydrocarbons may be used, for example Engelhard F-24 clay, Filtrol 24, Filtrol 25, and Filtrol 62, Attapulgus clay, or Tonsil clay (or a combination of any two or more of the foregoing). A manway207may be provided along the body210to allow access into the interior space212. A manway225above the first head270may provide additional access into the interior space212. The body210of the vessel300may include, optionally substantially uniform, a length218and a width (diameter)220. Generally, the width220corresponds to the diameter of the substantially cylindrical structure240.

The clay treatment apparatus16may include at least one or a plurality of inlets250for receiving a fluid and at least one outlet or plurality of outlets260for an exiting fluid. Generally, the at least one inlet250and at least one outlet260may be pipes or other structures for conveying fluids to and from the apparatus16. Usually, the at least one inlet250is positioned at a top of the apparatus16and the at least one outlet260may be positioned at a bottom of the apparatus16. Connected to the inlet pipe250is one or a plurality of distributor nozzles211, which serve to distribute the flow of the un-treated hydrocarbon fluid within the interior of the body210. The un-treated hydrocarbon fluid thus flows from the distributor nozzles211into the body210, which contains the active material216, and as it passes downward through the active material, the hydrocarbon fluid is treated to remove the unwanted impurities.

As is generally known in the art, a common type of liquid collector assembly suitable for use in clay treatment apparatuses includes a plurality of cylindrical conduits extending horizontally into the clay bed about a common transverse plane of the vessel at a constant height. The cylindrical conduits have perforated surfaces and/or a wire screen to prevent clay particle entry into the conduits, are each closed at one end, and are each in common flow communication with a piping manifold at the opposite end. As previously noted, however, the clay treatment apparatus of the present disclosure does not include a traditional collector structure, and accordingly it does not include any concrete disposed in the second or lower head portion280of the body210to support such a collector structure. In place of the collector, to provide an effective separating means to withdraw the treated fuel from the clay treatment apparatus, a support structure300is provided, which will be described in greater detail below with additional reference toFIGS. 3 and 4.

Particularly,FIG. 3provides a vertical cross-section and enlarged view of the lower head portion280of apparatus16, andFIG. 4provides a horizontal cross-section and enlarged view of the lower head portion280. As shown therein, the support structure300includes first and second concentric support rings302,303that are coupled, at a lower end thereof, with the body210(of the lower head portion280), and at an upper end thereof, with a clay retention structure305. Concentric support rings302,303may be continuous along their circumference, or they may be discontinuous (i.e., having gaps therealong). The second or inner support ring303will have a greater height due to the increased distance between the body210and the clay retention structure305at the lower end of the second head280.

The clay retention structure305includes a perforated support plate311with a wire mesh312disposed thereover. The retention structure may be circular in shape to correspond with the shape of the vessel240, although it is not necessary that the retention structure305have as great of a diameter333as the vessel240(i.e., diameter220). That is, the periphery of the clay retention structure305and the interior of the body210need not be provided in abutting adjacency, but it may be desirable to have such abutting adjacency in some embodiments to prevent clay from bypassing. The perforated support plate311may be coupled with the wire mesh312using a plurality of fastening devices319, such as screws bolts, and the like.

The perforated support plate311may have a plurality of perforations317therein which may be substantially uniform in size (for example within about plus or minus 20% area of each other, such as about plus or minus 5% area). Further, the perforations317may be substantially equally spaced from each other and uniformly about the plate311so that substantially equal amounts of treated fuel will flow through each perforation. In other words, the flow rate through each perforation may be substantially the same, e.g., within about 20% of each other. The combined cross-sectional area of the perforations317in the plate311may be from about 0.3 to about 30%, for example from about 0.6 to about 10% of the total cross-sectional area of the plate311. Each perforation may have a cross-sectional area of from about 0.00001 to about 0.7%, such as from about 0.0008 to about 0.35% based on the diameter333of the clay retention structure305. Generally, perforation317sizes of from about ⅛ to about ¾ inch may be employed in such perforated plate311.

The wire mesh312may be formed as a profile wire screen using no. 63 wire. The openings in the wire mesh may be from about 0.003 to about 0.013 inch, for example about 0.005 to about 0.010 inch. Such profile wire screens have traditionally been used for the mesh required for collector assemblies, and as such are well-suited to retaining the smaller clay particle sizes found in clay treatment apparatuses. In some embodiments, if profile wire screen is used, it may not be necessary to have the additional perforated plate, as the profile wire has structural stability.

In operation, the fuel flows downward through the active clay material216, passes through the wire mesh312, and then passes through the perforated plate311. Thereafter, from the lower head280, the treated fuel passes through the outlet nozzle260positioned at the base of the vessel240. The active clay material216, which is too large to pass through the wire mesh312, is effectively retained by the clay retention structure305. Additionally, due to the fact that a separate collector is not required (which was traditionally positioned above a concrete support), the entire amount of clay material216above the retention structure305, not just that part above the collector, may be used for treating the fuel, thus improving the efficiency of the clay treatment apparatus16. In other words, vessel volume can be reduced.

Accordingly, described herein are various embodiments of clay treatment apparatuses for removing unwanted contaminants from a hydrocarbon liquid composition, as well as embodiments of methods for processing hydrocarbon products that employ the use of such clay treatment apparatuses. The disclosed clay treatment apparatuses include perforated plate and wire mesh support structures that retain the active clay material at the bottom head portion of the vessel, and serve in place of the traditional collector structure. Accordingly, there is no need to pour concrete into the apparatus after installation thereof at the installation site to support a collector. The disclosed clay treatment apparatuses may thus be provided in modular form with the perforated plate and wire mesh support structure pre-installed at the fabrication site, to reduce the installation site work required to install the clay treatment apparatus.