Patent Description:
Gaseous chemicals may be fed into reactors or other vessels through feed distributors. Feed distributors may be utilized to promote balanced distribution of a feed chemical stream into such reactors or vessels. Such distribution of feed chemicals may promote preferred reactions and may maintain mass transport equilibriums in chemical systems. <CIT> discloses an FCC feed injection arrangement which injects feed transversely from sides of a restricted opening into a stream of FCC catalyst to provide feed and catalyst contacting. <CIT> describes a distributor of a feed into a vessel allowing the separated flow of a part of the feed into the vessel and a part of the feed back out of the vessel.

In a number of chemical processes, chemical feed streams are fed through chemical feed distributors into a hot environment, such as a reactor or a combustor. These hot environments may elevate the circumferential maximum surface temperature of the chemical feed distributors and may increase the risk of formation of carbonaceous deposits, referred as coking thereafter. This is particularly problematic in fluidized bed vessels, where fluidized solids in the vessel greatly enhances the heat transfer from the hot environment to the feed distributor through radiative and conductive heat transfer. In turn, the coking may create a risk of plugging and flow maldistribution. Accordingly, there is a need for improved chemical feed distributors. It has been found that chemical feed distributors which distribute only a portion of the chemical feed stream into the vessel, where another portion of the chemical feed stream is not fed into the vessel, may promote reduced peak surface temperatures on the chemical feed distributor. Embodiments of such chemical feed distributors are described herein. One or more embodiments of such chemical feed distributors may maintain a relatively steady circumferential maximum surface temperature and, therefore, reduce the risk of coking and the side effects associated with coking. Embodiments of the present disclosure meet this need by utilizing a chemical feed distributor with chemical feed stream recirculation, such that linear velocity may be maintained and stagnant zones within the chemical feed distributor may be reduced.

Apparatus according to one aspect of the invention is provided according to claim <NUM>.

A method for distributing a chemical feed stream according to a second aspect of the invention is provided according to claim <NUM>.

Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows and the claims.

The present disclosure is directed, according to one or more embodiments described herein, towards chemical feed distributors and methods for using such. Generally, the chemical feed distributors described herein may comprise a chemical feed inlet, a body comprising one or more walls, a plurality of primary chemical feed outlets, and a secondary feed outlet. A chemical feed stream may be passed through the chemical feed inlet. The chemical feed steam, as described herein, generally includes only a first portion and a second portion, which are equivalent in composition. A first portion of the chemical feed stream may be passed out of the plurality of primary chemical feed outlets, and the second portion may be passed out of the secondary chemical feed outlet.

Numerous embodiments of chemical feed distributors are described with respect to the appended drawings. However, as presently described, these embodiments may share common themes such as the passing of the chemical feed stream through primary and secondary chemical feed stream outlets. For example, <FIG>, <FIG> each depict embodiments that similarly include primary and secondary chemical feed outlets.

Referring now to <FIG>, <FIG>, according to one or more embodiments, the chemical feed distributor <NUM> may comprise a chemical feed inlet <NUM>. The chemical feed inlet <NUM> may pass a chemical feed stream <NUM> into the chemical feed distributor <NUM>. Accordingly, the chemical feed stream <NUM> may pass through the chemical feed inlet <NUM> into the chemical feed distributor <NUM>. As described herein, the chemical feed inlet <NUM> may refer to a place of entry in a vessel <NUM> that allows the chemical feed distributor <NUM> and the chemical feed stream <NUM> within the chemical feed distributor <NUM> to pass into the vessel <NUM>.

The chemical feed distributor <NUM> may comprise a body <NUM>. The body <NUM> may comprise one or more walls <NUM>. The body <NUM> may also comprise a plurality of primary chemical feed outlets <NUM>. As described herein, the plurality of primary chemical feed outlets <NUM> may be openings in the or more walls <NUM> of the body <NUM> and may provide a passage for the chemical feed stream <NUM> from the chemical feed distributor <NUM> to the vessel <NUM>. In embodiments, the plurality of chemical feed outlets <NUM> may be arrange in a singular row along the chemical feed distributor. In other embodiments, as shown in <FIG>, the plurality of chemical feed outlets <NUM> may be arrange in an alternating position along the chemical feed distributor <NUM>, such as two rows. It is contemplated that the chemical feed outlets <NUM> may be arrange in any configuration along the chemical feed distributor <NUM>. The plurality of chemical feed outlets <NUM> may comprise orifices 107A at the start of each chemical feed outlet <NUM> to create pressure drop and create more even distribution. The plurality of chemical feed outlets <NUM> may also comprise diffusers 107B to slow the superficial gas velocity passing through the plurality of chemical feed outlets <NUM> so as not to cause catalyst attrition or chemical feed distributor <NUM> damage. The diffusers 107B may permit the gas velocity to be in a range from <NUM> feet per second (ft/sec) (<NUM> metres per second) to <NUM> ft/sec (<NUM> metres per second).

The one or more walls <NUM> may define an elongated chemical feed stream flow path <NUM>. The plurality of primary chemical feed outlets <NUM> may be spaced along at least a portion of the length of the elongated chemical feed stream flow path <NUM>. The plurality of primary chemical feed outlets <NUM> may be operable to pass the first portion <NUM> of the chemical feed stream <NUM> out of the chemical feed distributor <NUM> and into a vessel <NUM>. A secondary chemical feed outlet <NUM> may be downstream of the plurality of primary chemical feed outlets <NUM>. The secondary chemical feed outlet <NUM> may be operable to pass the second portion <NUM> of the chemical feed stream <NUM> out of the chemical feed distributor <NUM>. The second portion <NUM> of the chemical feed stream <NUM> may be passed through the chemical feed distributor <NUM> and may not enter the vessel <NUM>. As used herein, the secondary chemical feed outlet <NUM> may refer to a place of exit in the vessel <NUM> that allows the chemical feed distributor <NUM> and any remaining portion of the chemical feed stream <NUM> within the chemical feed distributor <NUM> to pass out of the vessel <NUM>. The remaining portion of the chemical feed stream <NUM> that may pass through the secondary chemical feed outlet <NUM> may correspond to the portion of the chemical feed stream <NUM> that is not passed from the chemical feed distributor <NUM> to the vessel <NUM> via the plurality of primary chemical feed outlets <NUM>.

During operation, the chemical feed stream <NUM> may be fed at a relatively cool temperature compared to the temperature inside the vessel <NUM>. According to one or more embodiments, the differential between the temperature of the chemical feed stream <NUM> and the temperature inside the vessel <NUM> may greater than <NUM>, such as greater than <NUM>, greater than <NUM>, greater than <NUM>, greater than <NUM>, greater than <NUM>, greater than <NUM>, or greater than <NUM>. In embodiments, the temperature inside the vessel <NUM> may be greater than <NUM> and the temperature of the chemical feed stream <NUM> may be lower than the temperature inside the vessel. During operation, the temperature inside the vessel <NUM> may begin to heat the chemical feed distributor <NUM> and, therefore, may elevate the circumferential maximum surface temperature of the chemical feed distributor <NUM>. Circumferential maximum surface temperature may refer to the highest surface temperature throughout the chemical feed distributor <NUM>. This may also elevate the temperature of the chemical feed stream <NUM> within the chemical feed distributor <NUM>. If the circumferential maximum surface temperature of the chemical feed distributor <NUM> or the temperature of the chemical feed stream <NUM> inside the chemical feed distributor <NUM> increases too much, the chemical feed stream <NUM> may begin to deposit coke on the chemical feed distributor <NUM>. When coke deposits on the chemical feed distributor <NUM>, plugging may begin at the plurality of primary chemical feed outlets <NUM>, which could result in flow maldistribution, which may result in operational issues. As used in the present disclosure, "flow maldistribution" may refer to differences in uniform flow distribution between the plurality of primary chemical feed outlets <NUM>.

According to one or more embodiments of the present disclosure, the secondary chemical feed outlet <NUM> may be downstream of the plurality of primary chemical feed outlets <NUM>. The secondary chemical feed outlet <NUM> may be operable to pass the second portion <NUM> of the chemical feed stream <NUM> out of the chemical feed distributor <NUM>. Passing the second portion <NUM> of the chemical feed stream <NUM> out of the chemical feed distributor <NUM> may decrease the risk of coking, and, in turn, the risk of plugging and flow maldistribution. Without being bound to any particular theory, the total flow rate of the chemical feed stream <NUM> in the chemical feed distributor <NUM> may be increased as the second portion <NUM> of the chemical feed stream <NUM> is passed out of the chemical feed distributor <NUM> and not actually entering the vessel <NUM>. This increased flow rate of the chemical feed stream <NUM> may not substantially effect the flow rate of chemical feed stream <NUM> entering the vessel <NUM>, as the first portion <NUM> of the chemical feed stream <NUM>, may remain the same as if there was no recirculation of the second portion <NUM> of the chemical feed stream <NUM>. Without being bound to any particular theory, this increased flow rate of the chemical feed stream <NUM> may reduce stagnation in the chemical feed distributor <NUM>. This reduction in stagnation may result in maintaining a desirable Reynolds number where the chemical feed stream <NUM> within the chemical feed distributor <NUM> is rapidly moving through the chemical feed distributor <NUM>. With an increased flow of the chemical feed stream <NUM> within the chemical feed distributor <NUM>, the circumferential maximum surface temperature of the chemical feed distributor <NUM> may remain low enough such that coking may be minimized. That is, this desirable Reynolds number may effectively minimize coking, and, in turn, plugging of the plurality of primary chemical feed outlets <NUM> and flow maldistribution.

As used in this disclosure, a "chemical feed" may refer to any process feed stream or fuel gas, such as, but not limited to, methane, natural gas, ethane, propane, hydrogen, or any gas that comprises energy value upon combustion. Additionally, as used in this disclosure, a "vessel" may refer to a hollow container for holding a gas or solids, such as, a reactor or combustor in which one or more chemical reactions may occur between one or more reactants optionally in the presence of one or more catalysts. The vessel may have a solid particle volume fraction up to <NUM> vol. % and the superficial velocity of the gas in the vessel may be higher than the minimum fluidization velocity of the solid particles.

As used in this disclosure, the terms "upstream" and "downstream" may refer to the relative positioning of elements with respect to the direction of flow of the process streams. A first element of a system may be considered "upstream" of a second element if process streams flowing through the system encounter the first element before encountering the second element. Likewise, a second element may be considered "downstream" of the first element if the process streams flowing through the system encounter the first element before encountering the second element.

Additionally, as used in the present disclosure "coking" may refer to the formation of carbonaceous deposits, or coke. "Plugging" may refer to an accumulation of coke such that a passage or port may be partially restricted or completely blocked.

Referring to <FIG>, in some embodiments, the one or more walls <NUM> may define an upstream fluid passage <NUM> and a downstream fluid passage <NUM> of the elongated chemical feed stream flow path <NUM>. The upstream fluid passage <NUM> may be in fluid communication with the chemical feed inlet <NUM>. The upstream fluid passage <NUM> may be in fluid communication with the downstream fluid passage <NUM>. The downstream fluid passage <NUM> may be in fluid communication with the plurality of primary chemical feed outlets <NUM> and with the secondary chemical feed outlet <NUM>.

According to one or more embodiments, the upstream fluid passage <NUM> may be separated from the downstream fluid passage <NUM> by one or more walls <NUM>. A first wall 106A may define the upstream fluid passage <NUM>. A second wall 106B, in conjunction with the first wall 106A, may define the downstream fluid passage <NUM>. A third wall 106C may serve as an end of the chemical feed distributor <NUM>. The third wall 106C may be perpendicular to the first wall 106A and second wall 106B. It is contemplated that the third wall 106C may also comprise other geometries. The third wall 106C may be linear, rounded, or pointed. For the upstream fluid passage <NUM> to be in fluid communication with the downstream fluid passage <NUM>, the body <NUM> of the chemical feed distributor <NUM> may comprise a void between the end of the first wall 106A and the third wall 106C. The void between the end of the first wall 106A and the third wall 106C may allow the chemical feed stream <NUM> to fluidly pass from the upstream fluid passage <NUM> to the downstream fluid passage <NUM>.

According to one or more embodiments, the downstream fluid passage <NUM> may surround the upstream fluid passage <NUM>. In some embodiments, the downstream fluid passage <NUM> may be completely surrounded by the upstream fluid passage <NUM>. In other embodiments, a wall <NUM> of the downstream fluid passage <NUM> may be in contact with a wall <NUM> of the upstream fluid passage <NUM>, such that the downstream fluid passage <NUM> does not completely surround the upstream fluid passage <NUM>. The downstream fluid passage <NUM> and upstream fluid passage <NUM> may comprise any combination of various geometries. For example, the upstream fluid passage <NUM> may comprise a cylindrical or rectangular shape. The downstream fluid passage <NUM> may comprise a cylindrical shell or rectangular shell shape surrounding the cylindrical shape. The downstream fluid passage <NUM> may comprise a shell (i.e., a hollow geometry) as the downstream fluid passage <NUM> may partially or completely surround the upstream fluid passage <NUM>. Similarly, the upstream fluid passage <NUM> may, for example, comprise a circular, rectangular, or trapezoidal cross-sectional shape. The downstream fluid passage <NUM> may comprise a circular shell, rectangular shell, or trapezoidal shell cross-sectional shape. It is contemplated that, in embodiments, the downstream fluid passage <NUM> may not necessarily comprise a shell or hollow geometry. In embodiments, the downstream fluid passage <NUM> may not surround the upstream fluid passage <NUM>. Thus, in embodiments, the downstream fluid passage <NUM> may comprise a cylindrical, rectangular, circular, or trapezoidal shape.

According to one or more embodiments, the upstream fluid passage <NUM> and the downstream fluid passage <NUM> may form a co-axial geometry. In other embodiments, the upstream fluid passage <NUM> and the downstream fluid passage <NUM> may form an off-center geometry. Said differently, the upstream fluid passage <NUM> and the downstream fluid passage <NUM> may be concentric or eccentric. According to one or more embodiments, the upstream fluid passage <NUM> may be hermetic. That is, the upstream fluid passage <NUM> may be airtight such that the upstream fluid passage <NUM> does not combine with the downstream fluid passage <NUM> until the point of where the upstream fluid passage <NUM> is in fluid communication with the downstream fluid passage <NUM>.

Referring to <FIG>, according to one or more embodiments, the body <NUM> may consist of a tube. As previously discussed, the body <NUM> may be defined by one or more walls <NUM>. The one or more walls <NUM> may define a first straight tube segment <NUM>, a connector tube segment <NUM>, and a second straight tube segment <NUM>. The first straight tube segment <NUM> may be connected to the chemical feed inlet <NUM>. The first straight tube segment <NUM> may also be connected to the connector tube segment <NUM>. The connector tube segment <NUM> may be connected to the first straight tube segment <NUM> and the second straight tube segment <NUM>. The second straight tube segment <NUM> may be connected to the secondary chemical feed outlet <NUM>. Together, the first straight tube segment <NUM>, the connector tube segment <NUM>, and the second straight tube segment <NUM> may define the elongated chemical feed stream flow path <NUM>. The chemical feed stream <NUM> may enter the first straight tube segment <NUM> through the chemical feed inlet <NUM>. The chemical feed stream <NUM> may pass through the first straight tube segment <NUM>, the connector tube segment <NUM>, and the second straight tube segment <NUM>. The first portion <NUM> of the chemical feed stream <NUM> may enter the vessel <NUM> through the plurality of primary chemical feed outlets <NUM>. As previously discussed, the plurality of primary chemical feed outlets <NUM> may be spaced along the length of the elongated chemical feed stream flow path <NUM>. The second portion <NUM> of the chemical feed stream <NUM> may remain in the chemical feed distributor <NUM>, such that it does not pass into the vessel <NUM>. The second portion <NUM> of the chemical feed stream <NUM> may exit the chemical feed distributor <NUM> via the secondary chemical feed outlet <NUM>.

According to one or more embodiments, the first straight tube segment <NUM> and the second straight tube segment <NUM> may be substantially parallel. In some embodiments, the connector tube segment <NUM> may be U-shaped (such that the connector tube segment <NUM> comprises a <NUM>° bend). In such an embodiment, the first straight tube segment <NUM> and the second straight tube segment <NUM> may be parallel. It is contemplated that, in some embodiments, a plurality of connector tube segments <NUM> may be used such that the chemical feed distributor <NUM> comprises a plurality of first straight tube segments <NUM> and a plurality of second straight tube segments <NUM> between the chemical feed inlet <NUM> and secondary chemical feed outlet <NUM>.

Referring to <FIG>, according to one or more embodiments, the body <NUM> may be shaped to have a contour which substantially follows the vessel <NUM> perimeter. In some embodiments, the vessel <NUM> may be substantially circular. Accordingly, the body <NUM> may comprise a circular or ring shape. The first wall 106A may define the elongated chemical feed stream flow path <NUM>. The first wall 106A may comprise a plurality of primary chemical feed outlets <NUM>, as previously detailed herein. As previously described with respect to <FIG>, and <FIG>, the chemical feed stream <NUM> may enter the chemical feed distributor <NUM> via the chemical feed inlet <NUM>. The chemical feed stream <NUM> may travel along the elongated chemical feed stream flow path <NUM> of the chemical feed distributor <NUM>. The first portion <NUM> of the chemical feed stream <NUM> may enter the vessel <NUM> through the plurality of primary chemical feed outlets <NUM>. The second portion <NUM> of the chemical feed stream <NUM> may remain in the chemical feed distributor <NUM>, such that it does not pass into the vessel <NUM>. The second portion <NUM> of the chemical feed stream <NUM> may exit the chemical feed distributor <NUM> via the secondary chemical feed outlet <NUM>.

Referring to <FIG>, a schematic cutaway view of an embodiment of a vessel <NUM> is shown. <FIG> shows a vessel <NUM> used as a fluidized fuel gas combustor system for a catalytic dehydrogenation process. However, as detailed herein, the chemical feed distributor <NUM> may be employed in a variety of vessels <NUM>. Referring again to <FIG>, the vessel <NUM> may include a lower portion <NUM> generally in the shape of a cylinder and an upper portion comprising a frustum <NUM>. The angle between the frustum <NUM> and an internal horizontal imaginary line drawn at the intersection of the frustum <NUM> and the lower portion <NUM> may range from <NUM> to <NUM> degrees. All individual values and subranges from <NUM> to <NUM> degrees are included and disclosed herein; for example the angle between the tubular and frustum <NUM> components can range from a lower limit of <NUM>, <NUM> or <NUM> degrees to an upper limit of <NUM>, <NUM>, <NUM> or <NUM> degrees. For example, the angle can be from <NUM> to <NUM> degrees, or in the alternative, from <NUM> to <NUM> degrees, or in the alternative, from <NUM> to <NUM> degrees, or in the alternative, from <NUM> to <NUM> degrees. Furthermore, in alternative embodiments, the angle can change along the height of the frustum <NUM>, either continuously or discontinuously. In some embodiments, the vessel <NUM> may be, or may not be, lined with a refractory material.

Spent or partially deactivated catalyst may enter the vessel <NUM> through downcomer <NUM>. In alternative configurations, the spent or partially deactivated catalyst may enter the vessel <NUM> from a side inlet or from a bottom feed, passing upward through the air distributor as described in <CIT> (Attorney Ref. DOW <NUM>). The used catalyst impinges upon and is distributed by splash guard <NUM>. The vessel <NUM> may further includes air distributors <NUM> which are located at or slightly below the height of the splash guard <NUM>. Above the air distributors <NUM> and the outlet <NUM> of downcomer <NUM> may be a grid <NUM>. Above the grid <NUM> may be a plurality of chemical feed distributors <NUM>. One or more additional grids <NUM> may be positioned within the vessel <NUM> above the chemical feed distributors <NUM>. In embodiments, the chemical feed distributors <NUM> may enter the vessel <NUM> and traverse substantially across the vessel <NUM> as described in <CIT> (Attorney Ref. DOW <NUM>).

As previously described herein, according to one or more embodiments, the method for distributing the chemical feed stream <NUM> may comprise passing the chemical feed stream <NUM> through the chemical feed inlet <NUM> into the chemical feed distributor <NUM>. The chemical feed stream <NUM> may consist of the first portion <NUM> and the second portion <NUM>. The method may also comprise passing the first portion <NUM> of the chemical feed stream <NUM> out of the chemical feed distributor <NUM>. The first portion <NUM> of the chemical feed stream <NUM> may pass through the plurality of primary chemical feed outlets <NUM> and into the vessel <NUM>. The method may further comprise passing the second portion <NUM> of the chemical feed stream <NUM> out of the chemical feed distributor <NUM> through the secondary chemical feed outlet <NUM>. As previously described herein, the secondary chemical feed outlet <NUM> may be downstream of the plurality of primary chemical feed outlets <NUM>. Accordingly, the second portion <NUM> of the chemical feed stream <NUM> may not enter the vessel <NUM>.

According to another embodiment, the method for distributing the chemical feed stream <NUM> may comprise passing the chemical feed stream <NUM> through the chemical feed inlet <NUM> into the chemical feed distributor <NUM>. Again, the chemical feed stream <NUM> may consist of the first portion <NUM> and the second portion <NUM>. The chemical feed distributor <NUM> may comprise a body <NUM> comprising one or more walls <NUM>. The one or more walls <NUM> may define the elongated chemical feed stream flow path <NUM> and the plurality of primary chemical feed outlets <NUM>. The plurality of primary chemical feed outlets <NUM> may be spaced along at least a portion of the length of the elongated chemical feed stream flow path <NUM>. The method may also comprise passing the first portion <NUM> of the chemical feed stream <NUM> along the elongated chemical feed stream flow path <NUM>. The first portion <NUM> of the chemical feed stream <NUM> may pass through the plurality of primary chemical feed outlets <NUM> out of the chemical feed distributor <NUM> and into the vessel <NUM>. The method may further comprise passing the second portion <NUM> of the chemical feed stream <NUM> out of the chemical feed distributor <NUM> through the secondary chemical feed outlet <NUM>. The second portion <NUM> of the chemical feed stream <NUM> may be passed through the chemical feed distributor <NUM> and may not enter the vessel <NUM>.

According to some embodiments, the flow rates of the chemical feed stream <NUM>, the first portion <NUM> of the chemical feed stream <NUM>, and the second portion <NUM> of the chemical feed stream <NUM> may be represented by a series of expressions. The flow rate of the chemical feed stream <NUM>, Ci, may be represented by Equation <NUM>. The flow rate of the first portion <NUM> of the chemical feed stream <NUM>, C<NUM>, may be represented by Equation <NUM>. The flow rate of the second portion <NUM> of the chemical feed stream <NUM>, C<NUM>, may be represented by Equation <NUM>, as shown below: <MAT> <MAT> <MAT>.

In Equations <NUM>, <NUM>, and <NUM>, as shown above, r is the ratio of the flow rate of the second portion <NUM> of the chemical feed stream <NUM> to the flow rate of the first portion <NUM> of the chemical feed stream <NUM> and Xis the nominal flow rate (that is, the flow rate of the portion of the chemical feed stream <NUM> (the first portion <NUM>) that passes out of the chemical feed distributor <NUM> and into the vessel <NUM>).

In embodiments, the ratio of the flow rate of the second portion <NUM> of the chemical feed stream <NUM> to the flow rate of the first portion <NUM> of the chemical feed stream <NUM> may be from <NUM> to <NUM>. For example, the ratio of the flow rate of the second portion <NUM> of the chemical feed stream <NUM> to the flow rate of the first portion <NUM> of the chemical feed stream <NUM> may be from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, or from <NUM> to <NUM>.

In some embodiments, the ratio of the flow rate of the second portion <NUM> of the chemical feed stream <NUM> to the flow rate of the first portion <NUM> of the chemical feed stream <NUM> may be from <NUM> to <NUM>. For example, the ratio of the flow rate of the second portion <NUM> of the chemical feed stream <NUM> to the flow rate of the first portion <NUM> of the chemical feed stream <NUM> may be from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, or from <NUM> to <NUM>.

According to one or more embodiments, the method may further comprise recycling the second portion <NUM> of the chemical feed stream <NUM>. The second portion <NUM> of the chemical feed stream <NUM> that passes out of the chemical feed distributor <NUM> may be combined with the chemical feed stream <NUM> prior to the chemical feed stream <NUM> passing through the chemical feed inlet <NUM>.

According to one or more embodiments, the temperature inside the vessel <NUM> may be greater than <NUM> and the circumferential maximum surface temperature of the chemical feed distributor <NUM> may not exceed the temperature inside the vessel <NUM>. In other embodiments, the temperature inside the vessel <NUM> may be greater than <NUM> and the circumferential maximum surface temperature of the chemical feed distributor <NUM> may not exceed <NUM>.

As further discussed below, <FIG>, and <FIG> further demonstrate the circumferential maximum surface temperature and peak surface temperature of the chemical feed distributor <NUM> according to embodiments described herein.

As previously described herein, the chemical feed distributor <NUM> of the embodiments herein may reduce the risk of coking. As coking may create a risk of plugging and flow maldistribution, the chemical feed distributor <NUM> of the embodiments herein may reduce the risk of plugging and flow maldistribution. Flow maldistribution may also be caused by the heating up of the chemical feed stream <NUM> within the chemical feed distributor <NUM>, which may be referred to as thermally-induced flow maldistribution. As the temperature of the chemical feed stream <NUM> within the chemical feed distributor <NUM> increases, the density of the chemical feed stream <NUM> may decrease. Mass flow rate is proportional to the square root of the gas density. If the density of the chemical feed stream <NUM> decreases along a length of the chemical feed distributor <NUM>, the mass flow rate may also decrease along the length of the chemical feed distributor <NUM>. However, according to one or more embodiments of the present disclosure, the temperature increase of the chemical feed stream <NUM> may be lower, which in turn decreases any change in the density of the chemical feed stream <NUM>. Therefore, the thermally-induced flow maldistribution may be decreased.

In embodiments of the present disclosure, the relative reduction in flow maldistribution (including thermally-induced flow maldistribution) may be less than ± <NUM>%, such as less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, less than ± <NUM>%, or less than ± <NUM>%. Flow maldistribution may be determined using a computational fluid dynamics (CFD) program ANSYS Fluent® which can numerically predict the 3D compressible flow and conjugated heat transfer in the system following the first principle mass, momentum and energy conservation laws. The flow maldistribution is simply the deviation from a perfect average mass distribution at various points along the distributor.

As shown in <FIG>, the embodiments of the present disclosure, where a second portion <NUM> of the chemical feed stream <NUM> is passed out of the chemical feed distributor <NUM>, demonstrate a decreased flow maldistribution as compared to an embodiment where a second portion <NUM> of the chemical feed stream <NUM> is not passed out of the chemical feed distributor <NUM>. In fact, the flow maldistribution of the present embodiments may be less than ± <NUM>%. Conversely, the flow maldistribution of an embodiment where a second portion <NUM> of the chemical feed stream <NUM> is not passed out of the chemical feed distributor <NUM> may be as high as ± <NUM>%, as shown in <FIG>.

The various embodiments of systems and processes for distributing a chemical feed through a chemical feed distributor will be further clarified by the following examples. The examples are illustrative in nature, and should not be understood to limit the subject matter of the present disclosure.

In Example <NUM>, a computational fluid dynamic (CFD) model was used to compare a chemical feed distributor with feed recirculation to a chemical feed distributor without feed recirculation. A gas stream comprising methane, ethylene, and propylene was fed into the chemical feed distributors at <NUM>. The chemical feed distributors then directed the gas stream into a fluidized bed reactor operating at <NUM>. Both chemical feed distributors have the same gas stream flow rate. However, in the chemical feed distributor with feed recirculation, half of the gas stream was allowed to enter the fluidized bed reactor, while the remaining half of the gas stream was passed through the entirety of the chemical feed distributor and recirculated.

As shown in <FIG> and <FIG>, an embodiment according the present disclosure where a second portion of the chemical feed stream is passed out of the chemical feed distributor (<FIG>) is compared with an embodiment where a second portion of the chemical feed stream is not passed out of the chemical feed distributor (<FIG>). The peak surface temperatures of the feed stream at each of the chemical feed distributors internal wall surfaces were obtained from the CFD model. Compared to the chemical feed distributor without feed recirculation, the chemical feed distributor with feed recirculation demonstrates a lower peak surface temperature. As seen in <FIG>, a distal end (the end opposite the chemical feed inlet) of the chemical feed distributor without feed recirculation is much hotter than that of the chemical feed distributor where a second portion of the chemical feed stream is passed out of the chemical feed distributor. <FIG> demonstrates a much more uniform temperature across the length of the chemical feed distributor where a second portion of the chemical feed stream is passed out of the chemical feed distributor (<NUM>), as compared to a chemical feed distributor where a second portion of the chemical feed stream is not passed out of the chemical feed distributor (<NUM>). Further, <FIG> demonstrates that the peak surface temperature that does not reach temperatures as high as an embodiment where a second portion of the chemical feed stream is not passed out of the chemical feed distributor (<NUM>). This lower peak surface temperature may be due to the second portion of the chemical feed stream that passes out of the chemical feed distributor. It will be apparent to those skilled in the art that the peak surface temperature may be adjusted based on the process needs by tuning the feed recirculation rate to reduce the risk of coking.

Claim 1:
Apparatus comprising a vessel (<NUM>) and a chemical feed distributor (<NUM>) passing therein, the chemical feed distributor (<NUM>) comprising:
a chemical feed inlet (<NUM>) that passes a chemical feed stream (<NUM>) into the chemical feed distributor (<NUM>), the chemical feed stream (<NUM>) consisting of a first portion (<NUM>) and a second portion (<NUM>);
a body (<NUM>) comprising one or more walls (<NUM>) and a plurality of primary chemical feed outlets (<NUM>), wherein the one or more walls (<NUM>) define an elongated chemical feed stream flow path (<NUM>), wherein the plurality of primary chemical feed outlets (<NUM>) are spaced along at least a portion of the length of the elongated chemical feed stream flow path (<NUM>), and wherein the plurality of primary chemical feed outlets (<NUM>) are arranged to pass the first portion (<NUM>) of the chemical feed stream (<NUM>) out of the feed distributor (<NUM>) and into the vessel (<NUM>); and
a secondary chemical feed outlet (<NUM>) downstream of the plurality of primary chemical feed outlets (<NUM>), wherein the secondary chemical feed outlet (<NUM>) is arranged to pass the second portion (<NUM>) of the chemical feed stream (<NUM>) out of the chemical feed distributor (<NUM>) such that the second portion (<NUM>) of the chemical feed stream (<NUM>) is passed through the chemical feed distributor (<NUM>) and does not enter the vessel (<NUM>).