FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
1. Title of the invention: APPARATUS AND METHODS FOR THREE-PHASE
CATALYTIC HYDROPROCESSING
2. Applicant(s)
NAME NATIONALITY ADDRESS
BHARAT PETROLEUM CORPORATION LTD. Indian Bharat Bhavan, 4 & 6 Currimbhoy Road, Ballard Estate, Mumbai, Maharashtra 400001, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

TECHNICAL FIELD
[0001] The present subject matter relates generally to three-phase reactors
and methods for refining hydrocarbons, and in particular, to upflow reactors for hydroprocessing of heavy feedstock.
BACKGROUND
[0002] Three-phase (gas-liquid-solid) contacting and reacting systems are
extensively used in the chemical, biochemical, petrochemical, and petroleum refining industries. These reactors contain a fixed or continuously expanded bed of catalyst as a solid phase. Gas and liquid flow through the catalyst bed in co-current, counter-current, or cross-flow directions. In the petroleum refining industries, three-phase reactors are used for hydroprocessing to remove contaminants, such as metals, sulfur, and nitrogen from heavy feedstocks and to produce distillates from heavier fractions. Typically, these reactors are operated under elevated pressure and temperature in the presence of hydrogenation catalysts. Depending upon the feedstock and desired product quality, various commercially available processes based on fixed bed, moving bed, slurry bed, or ebullating bed reactors are employed in the refineries for hydroprocessing applications.
BRIEF DESCRIPTION OF DRAWINGS
[0003] The detailed description is described with reference to the
accompanying figures. In the figures, the left-most digit(s) of a reference number
identifies the figure in which the reference number first appears. The same numbers
are used throughout the drawings to reference like features and components where
possible.
[0004] Fig. 1 illustrates an example upflow baffled reactor enclosed in a
shell for three-phase catalytic hydroprocessing, in accordance with an embodiment
of the present subject matter.
[0005] Fig. 2(a) illustrates an example reactor stage, in accordance with an
embodiment of the present subject matter.

[0006] Fig. 2(b) illustrates a cross-sectional view of an example reactor
stage, in accordance with an embodiment of the present subject matter.
[0007] Fig. 2(c) illustrates a top view of an example reactor stage, in
accordance with an embodiment of the present subject matter.
[0008] Fig. 3(a) illustrates an example fluid distributor and an exploded
view of a channel, in accordance with an embodiment of the present subject matter.
[0009] Fig. 3(b) illustrates a top view of an example fluid distributor, in
accordance with an embodiment of the present subject matter.
[0010] Fig. 4(a) illustrates an example gas-liquid separator and Fig. 4(b)
illustrates a cross-sectional view of the gas-liquid separator, in accordance with an
embodiment of the present subject matter.
[0011] Fig. 5 illustrates a top view of an example catalyst support, in
accordance with an embodiment of the present subject matter.
[0012] Fig. 6 illustrates an example gas inlet portion, in accordance with an
embodiment of the present subject matter.
[0013] Fig. 7 illustrates another example upflow baffled reactor enclosed in
a shell for three-phase catalytic hydroprocessing, in accordance with an
embodiment of the present subject matter.
[0014] Fig. 8(a) illustrates an example reactor stage for the reactor shown
in Fig. 7, in accordance with an embodiment of the present subject matter.
[0015] Fig. 8(b) illustrates a top view of the reactor stage shown in Fig. 8(a),
in accordance with an embodiment of the present subject matter.
[0016] Fig. 9 illustrates a top view of another example fluid distributor, in
accordance with an embodiment of the present subject matter.
[0017] Fig. 10 illustrates a top view of another example fluid distributor, in
accordance with an embodiment of the present subject matter
DETAILED DESCRIPTION
[0018] The present subject matter relates generally to three-phase reactors
and methods for refining hydrocarbons, and in particular, to upflow reactors for hydroprocessing of heavy feedstock.

[0019] In the context of heavy oil processing, the hydroprocessing route has
emerged as a requirement for meeting stringent environmental norms and enhancing refining margins. In the past, extensive research has been performed to process heavy feedstock (hydrocarbon with initial boiling point (IBP) > 550 °C) in hydroprocessing reactors and various designs have been disclosed. At present, fixed bed process technology is employed in most of the petroleum refineries because of its technical maturity, low cost, and stable and reliable performance. However, because of the presence of metals in the heavy feedstock, the catalyst deactivation rate is higher. The heavy feedstock contains a reasonable amount of metals and coke precursors that deposit on the surface of the hydroprocessing catalyst during the process and leads to rapid deactivation. To overcome rapid deactivation of the catalysts in fixed bed reactors, moving bed or ebullating bed was developed and commercially used. These types of reactors differ from the fixed bed reactor in that fresh catalyst is added and spent catalyst is removed continuously from the reactor system during operation.
[0020] In moving bed reactors, the hydrogen and heavy feeds flow in a co-
current upward direction and the catalyst flows downward. The spent catalyst is removed from the bottom and fresh catalyst is added from top of the bed as per requirements, which resolves the coking problem faced in fixed bed reactors. Further, because of the upflow motion of feedstock and hydrogen, there is a very low pressure drop across the catalyst bed. This leads to elimination of bed plugging observed in a fixed bed reactor. The main disadvantages of these type reactors are the high capital cost associated with the equipment required for addition and removal of catalyst.
[0021] In an ebullating bed, hydrogen and feedstock flow concurrently
upward through a fluidized catalyst bed and leads to expansion of the catalyst bed consisting of suspended catalyst particle up to 20% compared to the volume of catalyst in the reactor when there is no flow. The process leads to complete mixing of catalyst particles and flowing gas-liquid streams. Because of the good heat and mass transfer, a low-pressure drop, and continuously moving catalyst bed, ebullating bed reactor has been integrated into a few refineries as an alternative to

fixed bed reactor to process heavy feedstock. However, because of the low catalyst particle density compared to that of the fixed bed reactor and arbitrary motion of reactants/products, there is gross back mixing in the ebullating bed. This causes lower reaction rates because of uniform concentration of reactants and product in the reactor. Therefore, there is a need to develop a process, which can substantially increase the conversion of heavy feedstock without coking (as in conventional fixed bed) and back mixing (as in ebullating bed). In conventional ebullated bed reactor systems (US7449103B2, US6436279B), an ebullating pump was used to re¬circulate the liquid in the reactor to maintain the expansion of catalyst bed and uniform temperature inside the reactor. Such seamless ebullating pumps operated at high temperature and pressure require high maintenance cost and there are safety concerns are associated with the process.
[0022] The present subject matter relates to an upflow baffled reactor
enclosed in a shell for three-phase catalytic hydroprocessing. The reactor comprises a reactor stage and a fluid distributor disposed below the reactor stage. The reactor stage comprises at least two riser stages and at least one downcomer stage. The riser stages comprise catalysts and fluid is allowed to rise up the first riser stage for reaction to occur. The riser can be used as a fixed catalyst bed or expanded catalyst bed. The liquid after reaction is allowed to come down through the downcomer stage, which then along with a gas is allowed to rise up and react in the second riser stage. A gas-liquid separator is disposed on top of the reactor stage, which allows for separation of liquid from gas. A first gas outlet and a first liquid channel disposed on top of the riser stage allow gas to be removed from the reactor and liquid from the gas-liquid separator to flow down the downcomer, respectively. A second liquid channel is disposed at a bottom portion of the downcomer stage to allow liquid to enter the second riser stage from the downcomer stage. A liquid outlet disposed on a top portion of the second riser allows liquid product to exit the reactor and a second gas outlet allows gas to be removed from the reactor. The fluid distributor at the bottom comprises a liquid inlet to allow liquid to enter the reactor stage and a plurality of channels passing through the fluid distributor. The plurality

of channels is fixed at the top of gas calming section to allow gas to enter and rise up the reactor stage.
[0023] The channels are closed from the top to avoid settling of solid
catalyst particles in the channels. The channels have holes in the circumference at
the top. The hole size and the number of holes can be designed to get the required
channel-to-bed pressure drop for uniform gas distribution from each hole. The
desired flow regimes for ebullated bed can be maintained by these types of
distributors. These types of distributors can be used for high temperature and highly
reactive processes. In various examples, more than one reactor stage may be used.
[0024] The reactor of the present subject matter allows for hydroprocessing
of heavy feedstock, the process being more energy efficient, flexible, and easy to implement. It also allows greater control over the process compared to conventional reactors and methods. Three-phase hydrotreating in accordance with the present subject matter provides lower pressure drop, lesser product inhibition, no dry spots in catalyst bed, reduced feed vaporization and higher Asphaltene conversion without precipitation in compare to conventional reactors.
[0025] The catalyst bed can be used as stationary or expanding bed. The
catalyst bed can be expanded about 5-20% as in an ebullating bed by varying the fluid flow rate in each riser. In the reactor of the present subject matter, the processed liquid from the top of the first riser flows downward in the downcomer due to gravity and enters the second riser from the bottom because of liquid head pressure difference. Hence, ebullating pump is not required in the process. This will reduce the back mixing compared to commercial ebullated bed. In addition, this leads to a significant reduction in capital cost, maintenance cost, and safety concerns. The liquid flow in the downcomers will work as a heat exchanger for the riser and uniform temperature along the catalyst bed can be maintained. Since product gases are removed from each reactor stage, there is less product inhibition. Fresh gas is introduced in each riser stage, which increases conversion rate. In addition, introduction of fresh gas obviates the need for a quench stream to prevent hot spots and heat generated by the reaction is removed along with the effluent gases. This leads to a significant reduction in capital costs.

[0026] Furthermore, each riser may be packed with different catalysts,
allowing for optimum use of the characteristics of each catalyst in the hydroprocessing reaction. In examples where more than one reactor stage is used, one riser and downcomer may be used as standby, which can be put into operation when another reactor stage is being replaced, for example, in case of coke formation, catalyst regeneration, or other technical issues. This will prevent reactor shutdown time and allow the reactor to be in continuous operation.
[0027] Aspects of the present subject matter are further described in
conjunction with the appended figures. It should be noted that the description and figures merely illustrate the principles of the present subject matter. It will thus be appreciated that various arrangements that embody the principles of the present subject matter, although not explicitly described or shown herein, can be devised from the description and are included within its scope. Moreover, all statements herein reciting principles, aspects, and implementations of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.
[0028] Fig. 1 illustrates an example upflow baffled reactor enclosed in a
shell for three-phase catalytic hydroprocessing, in accordance with an embodiment of the present subject matter. The upflow baffled reactor 100 may be enclosed in a shell 104. In an example, the shell 104 may be cylindrical in shape. The reactor 100 comprises a reactor stage 110. The reactor stage 110 comprises at least two riser stages 114 and at least one downcomer stage 118. The riser stage 114 comprises catalyst. In an example, the reactor 100 comprises a plurality of reactor stages 110. In various examples there may be several riser stages 114 (114a, 114b...) and several downcomer stages 118 (118a, 118b…). In an example, the shell 104 may be divided into several sections and each section may comprise a reactor stage 110. There may be any number of reactor stages 110 in a reactor. In an example, the number of reactor stages 110 may depend on the quality of product desired. The reactor 100 comprises a gas-liquid separator 120 disposed on top of the rector stage 110. In an example, each riser stage 114 (114a, 114b…) may comprise a gas-liquid separator 120 (120a, 12b…).

[0029] In an example, during operation of the reactor, a fluid comprising a
mixture of liquid and gas is allowed to rise up a first riser stage 114a, where a
hydroprocessing reaction occurs in the first riser stage 114a. In the riser stage 114a,
liquid and gas flow up co-currently. Because the fluid rises up in the riser stage 114,
this leads to better wetting of the catalyst and lower pressure drop compared to
conventional fixed bed reactors. In an example, the hydroprocessing reaction may
be hydrotreating of heavy feedstock to reduce the amount of contaminants, such as
sulfur, nitrogen, metals, and carbon residue and increase hydrogen content in the
heavy feedstock. In this example, the fluid comprises a mixture of heavy feedstock
and hydrogen gas. In various other examples, the hydroprocessing reaction may be
residue upgrading, desulfurization, denitrogenation, hydrogenation, hydrocracking,
petroleum product synthesis, and other three-phase catalytic or non-catalytic
reactions. Each riser stage 114 may be packed with different catalysts, allowing for
different reactions to occur in each riser stage 114, and the characteristics of each
type of catalyst may be used advantageously. In another example, one riser stage
114 and one downcomer stage 118 may be used as standby when no reaction occurs
in them. They may be used when another reactor stage 110 is replaced, for example,
because of coke formation, replacement of catalyst, catalyst regeneration, or other
technical issues. Use of a standby riser stage 114 and downcomer stage 118 allows
for continuous operation of the reactor 100 and there is no reactor downtime.
[0030] As the fluid rises to the top of a first riser stage 114a, the liquid may
be partially reacted. When it reaches the gas-liquid separator 120a, the liquid is separated from the gas. In an example, the partially reacted liquid may be allowed to flow down the downcomer stage 118a via a first liquid channel disposed on top of the riser stage 114a (not shown here) and the gas may be removed via a riser gas outlet (not shown here). In various examples, each gas liquid separator 120 may be connected to a separate riser gas outlet. The riser gas outlet may be fluidically connected to a reactor gas outlet 128 disposed on a top portion of the reactor 100. The reactor gas outlet 128 allows gases to be removed from the reactor 100. In an example, the gases removed may be effluent gas, excess hydrogen, liquid vapors, or product gases. The removal of gases from each riser within the reactor 100 leads

to reduced product inhibition. The gases removed from the reactor 100 may be sent for further processing, for example, separation, purification, etc.
[0031] The liquid flowing down the downcomer stage 118a may be allowed
to rise up the second riser stage 114b via a second liquid channel (not shown here) disposed at a bottom portion of the second riser stage 114b for further reaction. In an example, fresh gas may be allowed to enter the second riser stage 114b. Introduction of fresh gas in each riser stage 114 allows for increased conversion rate of the reaction occurring in the riser stage 114. In an example, when the reactor 100 comprises several reactor stages 110, the liquid feedstock may be converted to progressively increasing stages of reaction conversion in each of the reactor stages 110, and the product liquid may be collected from a final reactor stage 110. In various examples, when the hydroprocessing reaction is exothermic, for example, in hydrotreating, removal of the effluent gas from the reactor 100 allows heat to be removed from the reactor 100. This prevents formation of hot spots in the reactor and obviates the requirement of quench heads to introduce quench fluids to reduce temperature. The liquid flow through downcomer stage 118 also work as a heat-exchanger to the riser stage 114 and uniform temperature across the catalyst bed can be achieved.
[0032] The reactor 100 comprises a fluid distributor 130 disposed below the
reactor stage 110. In an example, the fluid distributor 130 is disposed within the shell 104. The fluid distributor comprises a liquid inlet 134 to allow liquid to enter the reactor stage 110. A plurality of channels 138 pass through the fluid distributor 130 and are fluidically connected to a gas inlet 142. Gas enters the reactor 100 via the gas inlet 142 and passes through the plurality of channels 138 and enters the reactor 100. In an example, when the shell 104 is cylindrical in shape, the fluid distributor 130 may be cylindrical in shape. In various examples, the fluid distributor 130 may a needle or tuyere-type sparger. In an example, gas in introduced through a tuyere type sparger. The fluid distributor 130 allows uniform distribution of liquid and gas to the reactor stages 110, ensures complete wetting of catalyst particles, breaking up of large gas bubbles leading to optimal mixing of reactants, and may act as a support for the catalyst bed.

[0033] The gas inlet 142 is connected to a gas inlet portion 150 disposed at
a bottom portion of the reactor 100. The gas inlet portion 150 comprises branches 154 (154a, 154b…) corresponding to the number of riser stages 114 in the reactor 100. The branches 154 are fluidically connected to the riser stages 114 and the branches 154 are not connected to each other. Each branch 154 is connected to one riser stage 114 so that gas may be supplied separately to each riser stage 114. In an example, when the reactor 100 comprises two riser stages 114a and 114b and one downcomer stage 118a, two branches 154a and 154b are connected to the first riser stage 114a and second riser stage 114b, respectively. In an example, hydrogen gas is fed via the gas inlet portion 150.
[0034] In an example, a calming portion 160 may be disposed above the gas
inlet portion 150. In the gas calming portion 160, gas enters from the bottom
through the branches 154 and sufficient pressure drop across the calming section is
maintained in order to get uniform distribution of gas through the plurality of
channels 138 placed at the top of calming portion 160. The calming portion 160
allows even distribution of gas before entry into the fluid distributor 130.
[0035] Fig. 2(a) illustrates an example reactor stage, in accordance with an
embodiment of the present subject matter. The reactor stage 110 comprises four riser stages 114a, 114b, 114c, and 114d; and four downcomer stages 118a, 118b, 118c, and 118d. In an example the reactor 100 may be cylindrical in shape and the plurality of reactor stages 110 may be arranged around a central axis of the reactor 100, such that each reactor stage 110 forms a quadrant of a circle. Fluid enters the reactor stage 110 via the fluid distributor 130. Liquid and gas from the fluid distributor rises up the riser 114a where hydroprocessing reaction occurs. Separated liquid flows down corresponding downcomer 118a and then rises up next riser stage 114b. Fresh gas may be fed into riser stage 114b. Liquid and gas react in the riser stage 114b and liquid may be separated from gas via the gas-liquid separator 120 (not shown here), and the liquid flows down downcomer 118b and rises in the next riser stage 114c. After reaction the liquid may be separated at the top of the riser stage 114c and liquid comes down in downcomer 118c. This liquid rises up in riser stage 114d and product liquid may be removed from the top of riser stage 114d. In

an example, riser stage 114d and downcomer stage 118d may be a standby reactor stage 110 that comes into operation when the any of the other riser stages 114a, 114b, or 114c are to be replaced.
[0036] Fig. 2(b) illustrates a cross-sectional view of an example reactor
stage, in accordance with an embodiment of the present subject matter. The arrows in the figure indicate the direction of flow of gas and liquid. The reactor 100 comprises three riser stages 114a, 114b, and 114c comprising catalysts; and two downcomer stages 118a and 118b. Liquid enters liquid inlet 134 and gas enters via gas inlet 142. The gas may pass through the calming portion 160 to allow gas to be distributed uniformly before entry into the fluid distributor 130. Both the liquid and gas rise up and flow co-currently in a first riser stage 114a where reaction occurs. The fluid distributor 130 may act as a support for the reactor stage 110, in addition to allowing fluid to rise up in the riser stages 114. In an example, layers of inert particles may be disposed on portions between the catalyst and the fluid distributor 130 to allow liquid to be evenly distributed before entering the riser stage 114. The inert particles may be silica or alumina balls of diameter of 3-6 mm. The height of the inert particles layer may be optimized based on the reactor design. In another example, an additional support, such as a screen or a mesh may be disposed on the fluid distributor 130. A second support 204 may be disposed on top of the reactor stage 110. In an example, the second support 204 may be a screen or a mesh having the mesh size less than that of catalyst particle size.
[0037] After reaction in the riser stage 114a, gas and liquid are separated in
gas-liquid separator 120a. As mentioned before, each riser stage 114 has a separate gas-distributor 120 to allow for separation of gas and liquid from the fluid rising up in that riser stage 114. Separated gas may be allowed to exit the riser stage 114a via a riser gas outlet 206a. Liquid may be allowed to flow into downcomer 118a via a first liquid channel 210, whence it flows down downcomer 118a. The liquid may then be allowed to enter riser stage 114b via a second liquid channel 220, whence it rises along with fresh gas fed from the fluid distributor 130. After reaction in the riser stage 114b, liquid comes down downcomer 118b and gas may be removed via riser gas outlet 206b. Liquid from downcomer 118b enters riser stage 114c and rises

up along with gas. In this example, riser stage 118c is the final riser stage 114 where reaction occurs. Gas may be removed from riser gas outlet 204c and the product liquid may be removed from liquid outlet 230. In an example where the rector stage 110 comprises two riser stages 114, the liquid outlet 230 may be disposed on a top portion of the second riser 114 to allow exit of the liquid product from the reactor 100. Gases from the riser gas outlet 206 may be removed from the reactor 100 via the reactor gas outlet 128.
[0038] Fig. 2(c) illustrates a top view of an example reactor stage, in
accordance with an embodiment of the present subject matter. In an example, the riser stages 114 and the downcomer stages 118 are arranged around a central axis of the reactor 100 and each reactor stage 110 forms a quadrant of a circle. In an example, the riser stages 114 may be filled with different catalysts. In another example, the riser stages 114 may be filled with the same catalyst.
[0039] Fig. 3(a) illustrates an example fluid distributor and an exploded
view of a channel, in accordance with an embodiment of the present subject matter. The fluid distributor 130 may be disposed below the reactor stage 110. The fluid distributor 130 may be fluidically connected to a liquid inlet 134 to allow liquid to enter the reactor stage 110 via the fluid distributor. A plurality of channels 138 pass through the fluid distributor 130 and are fluidically connected to the gas calming portion 160 (not shown here). In an example, when the shell 104 is cylindrical in shape, the fluid distributor 130 may be cylindrical in shape. In an example, the height of the plurality of channels present on a portion of the fluid distributor 130 is more than the second liquid channel 220 that is in contact with a riser stage 114. This allows gas to flow in each of the riser stages 114 and not in the downcomer stage 118. In another example, the fluid distributor 130 may comprise sets of plurality of channels 138 disposed on portions of the fluid distributor 130 that is in contact with the riser stage 114. In another example, the fluid distributor 130 is cylindrical in shape and the sets of plurality of channels 138 may be arranged along a central axis of the fluid distributor 130 so that each set of plurality of channels 138 forms a quadrant of a circle. In another example, portions of the fluid distributor

130 without the plurality of channels 138, which correspond to the downcomer
stages 118 do not allow fluid to flow up into the downcomer stages 116.
[0040] The plurality of channels 138 may be covered at the top 310 to
prevent any catalyst particles from setting down. A plurality of holes 320 may be disposed on the circumference on each of the channels 138 to allow gas to flow to the riser 114.
[0041] Fig. 3(b) illustrates a top view of the example fluid distributor shown
in Fig. 3(a), in accordance with an embodiment of the present subject matter. The plurality of channels 138 may arranged around the central axis of the fluid distributor 130 and the plurality of channels 138 are disposed on portions of the fluid distributor 130 that correspond to the riser stages 114. In various examples, the fluid distributor 130 may be one of a screen or perforated plate.
[0042] Fig. 4(a) illustrates an example gas-liquid separator and Fig. 4(b)
illustrates a cross-sectional view of the gas-liquid separator, in accordance with an embodiment of the present subject matter. Referring to Fig. 4(a), in an example, when the shell 104 is cylindrical, the gas-liquid separator 120 may be cylindrical in shape. The separator 120 may comprise separator portion 410 disposed on top of the riser stage 114. In an example, when there are more than one riser stages 114, different separator portions 410 may be disposed on top of each riser stage 114. Each separator portion 410 is fluidically connected to the corresponding riser stage 114, but the different separator portions 410 are not fluidically connected to each other.
[0043] Fig. 4(b) illustrates the cross-sectional view of gas-liquid separator
of a reactor stage 110. The gas-liquid separator 120 may be placed on top of the riser 114 and downcomer 118. A vertical baffle 420 may be placed between the riser 114 and downcomer 118 up to a certain height. The height of the baffle 420 can be decided based on flow rates of fluid mixer and separator volume. The bottom of the separator 120 may have a mesh screen 430 to stop catalyst particles from entering the separator 120. The mixed gas and liquid enters the separator 120 from top of the catalyst bed (riser 114) via the mesh screen 430 and rises up to the height of the baffle 420. After the baffle 420, because of the increased cross-sectional area,

the superficial velocity of the mixed fluid decreases significantly. Liquid is separated from gas due to density difference and flows through first liquid channel 440 into the downcomer 118 due to gravity. Gas rises in the separator 120 and collected from the top 450 for further processing.
[0044] Fig. 5 illustrates a top view of an example catalyst support, in
accordance with an embodiment of the present subject matter. In an example, the catalyst support 510 may be disposed on a bottom portion of the reactor stage 110. In this case, the catalyst support 510 may be disposed on top of the fluid distributor 130. In an example, the catalyst support 510 may be a plate with perforations. In an example, the catalyst support 510 may be in contact with the fluid distributor 130. In another example, the catalyst support 510 may be disposed at a certain height, for example, 10-20 mm, above the fluid distributor 130. The catalyst support 510 may comprise a mesh with various grid sizes. The strength of grid is enough to sustain the catalyst bed weight. The grid sizes and placement of the catalyst support 510 may be optimized to achieve good fluid distribution. The grid openings may be such that they allow fluid to flow up easily but do not allow any catalyst particles to settle down in the fluid distributor 130.
[0045] In another example, the catalyst support 510 may be disposed on a
top portion of the reactor stage 110. In another example, the second support 204
may be the same as the catalyst support 510. The catalyst support 510 may be a
screen or a mesh. The catalyst support 510 may be disposed horizontally within the
shell 104. In an example, the catalyst support 510 may be removably disposed in
the shell 104 to allow cleaning and inspection. The catalyst support grid may
prevent large bubbles from passing through and provide uniform distribution of
fluid. In another example, the catalyst support 510 may be disposed both at the
bottom and top of the reactor stage 110. In yet another example, the bottom portion
of the reactor stage 110 may be supported by the fluid distributor 130 and the second
support 204 may be disposed on a top portion of the reactor stage 110.
[0046] Fig. 6 illustrates an example gas inlet portion, in accordance with an
embodiment of the present subject matter. In an example, the gas inlet portion 150 is disposed on a bottom portion of the reactor 100. The gas inlet portion 150

comprises a gas inlet 142. The gas inlet 142 may be connected to branches 154. In an example, the gas inlet portion 150 may comprise at least two branches 154 to allow gas from one branch 154 to enter one riser stage 114. The number of branches 154 correspond to the number of riser stages 114. Each branch 154 allows gas to enter one riser stage 114. In an example, the gas inlet 142 may be connected to the branches 154 via a tube 610. The branches 154 may be connected to the calming portion 160, which may be disposed on top of the gas inlet portion 150, to allow uniform distribution of gas to the fluid distributor 130. The gas may then enter the riser stages 114 via the fluid distributor 130.
[0047] Fig. 7 illustrates another example upflow baffled reactor enclosed in
a shell for three-phase catalytic hydroprocessing, in accordance with an embodiment of the present subject matter. In an example, the reactor 700 comprises at least one reactor stage. The reactor stage may comprise riser stages 710 and downcomer stages 720. The reactor 700 may be cylindrical in shape and the plurality of reactor stages may be arranged in concentric circles around a central axis of the reactor 700. A fluid distributor 730 may be disposed below the reactor stages to allow fluid to enter the riser stages 710. The fluid distributor 730 may comprise a liquid inlet 734. A gas inlet portion 750 may be disposed on a bottom portion of the reactor 700 to allow gas to enter the reactor 700 via gas inlet 754. A calming portion 760 may be disposed above the gas inlet portion 750 to allow uniform distribution of the gas. During operation, liquid and gas may rise up a first riser stage 710 where reaction occurs. Liquid and gas may be separated in a gas-liquid separator 770 disposed on a top portion of the reactor 700. Liquid may be allowed to flow down a downcomer stage 720 and allowed to enter the next riser stage 710. Gas may be removed via a gas outlet 774. Gas and liquid may be allowed to rise up in the next riser stage 710 and the process may continue until the final riser stage 710. The liquid product may be collected via a liquid outlet and any product gases may be collected via gas outlet 774.
[0048] Fig. 8(a) illustrates an example reactor stage for the reactor shown
in Fig. 7, in accordance with an embodiment of the present subject matter. The reactor stage may comprise a plurality of riser stages 710 and downcomer stages

720 arranged in concentric circles around a central axis of the reactor 700. The riser stages 710 may comprise catalysts. In an example, all the riser stages 710 may comprise the same catalyst. In another example, the different riser stages 710 may comprise different catalysts. Gas and liquid rise up in the riser stage 710, where hydroprocessing reactions occur. Gas and liquid may be separated in the gas-liquid separator 770 and liquid may be allowed to flow down downcomer 720. The liquid then rises in the next riser stage 710 and the process continues until the final riser stage 710, after which product is collected. In an example, the first riser stage 710 may be the riser stage 710a disposed at the center of the reactor and the reaction may proceed outward so that the final riser stage may be the riser stage 710b disposed along the circumference of the reactor stage. In another example, the riser stage 710b disposed along the circumference may be the first riser stage and the riser stage 710a disposed at the center of the reactor stage may be the final riser stage. In another example, inert materials 810 may be disposed below the reactor stage to allow uniform distribution of fluid before entry into the reactor stage and prevent large bubbles from entering the reactor stage.
[0049] Fig. 8(b) illustrates a top view of the reactor stage shown in Fig. 8(a),
in accordance with an embodiment of the present subject matter. The riser stages 710 and the downcomer stages 720 are arranged in concentric circles around the central axis of the reactor.
[0050] Fig. 9 illustrates another example fluid distributor and calming
section, in accordance with an embodiment of the present subject matter. The fluid distributor 910 may be disposed on a bottom portion of the reactor stage. The fluid distributor 910 is fluidically connected to a liquid inlet and allows the liquid to enter the riser stages 710. A plurality of channels 920 may be disposed on the fluid distributor 910. The plurality of channels 920 may be arranged in concentric circles corresponding to the riser stages 710 of the reactor 700. The plurality of channels 920 may be connected to the gas inlet portion 750 via the calming portion 760 and allows gas to enter the riser stages 710. Gas may enter the gas inlet portion 750 via a gas inlet 754.

[0051] Fig. 10 illustrates a top view of another example fluid distributor, in
accordance with an embodiment of the present subject matter. The fluid distributor comprises a plurality of channels 920 arranged in concentric circles around the central axis of the reactor. The plurality of channels 920 correspond to the riser stages 710 and allow gas to enter the riser stages 710.
[0052] In an example, the reactor 100 and 700 may be used for
hydrotreating a feedstock. The hydrotreating reaction may take place at the temperature and pressure ranges of 315 – 480 ºC and 60-200 bar, respectively. The gas to oil ratio and liquid hourly space velocity are in the ranges of 10-1000 Nm3/m3 and 0.5-10 hr-1, respectively. The catalysts used may be one of silica, alumina, nickel, tungsten, platinum, palladium, or a combination thereof. The catalyst size may vary form 0.8-3 mm. The catalyst used for hydrotreating may be of any shape. In an example, the catalyst may be dense, hard, and have a spherical shape or extruded shape. The catalyst bed in each riser stage may have different hydrogenation activity depending on the nature of feedstock to selectively remove the contaminants to avoid bed clogging and to increase the catalyst life. In an example, catalysts with large pore size and greater metal removal properties may be used in the first riser stages. In another example, the catalysts used in second riser stage may have more desulfurization, denitrification, and carbon removal activity in comparison to the first riser stages.
[0053] Although specific examples relating to hydrotreating are discussed,
the reactor of the present subject matter may be used in any other hydroprocessing reactions such as, residue upgrading, desulfurization, denitrogenation, hydrogenation, hydrotreating, hydrocracking, petroleum product synthesis, and other three phase catalytic/non-catalytic processes.
[0054] Although embodiments for the present subject matter is described in
language specific to structural features, it is to be understood that the specific features and methods are disclosed as example embodiments for implementing the claimed subject matter.

I/We Claim:
1. An upflow baffled reactor (100,700) enclosed in a shell (104) for three-phase catalytic hydroprocessing, the reactor (100,700) comprising:
a reactor stage (110), wherein the reactor stage (110) comprises:
at least two riser stages (114,710) and at least one downcomer stage (118, 720), wherein the riser stages (114, 710) comprise catalysts and fluid is allowed to rise up a first riser stage (114a) for reaction to occur, liquid after reaction is allowed to come down the downcomer stage (118, 720), and the liquid from the downcomer stage (118, 720) and a gas is allowed to rise up and react in the second riser stage (114b);
a gas-liquid separator (120,770) disposed on top of the reactor stage (110) to allow for separation of liquid from gas;
a riser gas outlet (206) disposed on top of the riser stage (114, 710) to allow gas to be removed from the reactor (100,700);
a first liquid channel (210) disposed on top of the riser stage (114, 710) to allow liquid from the gas-liquid separator (120, 770) to flow down the downcomer;
a second liquid channel (220) disposed at a bottom portion of the downcomer stage (118, 720) to allow the liquid to rise up the riser stage (114, 710) from the downcomer stage (118, 720);
a liquid outlet (230) disposed on a top portion of the second riser (114b) to allow exit of the liquid product from the reactor (100,700); and
a reactor gas outlet (128) fluidically connected to the riser gas outlet (206) to allow the gas to be removed from the reactor (100,700); and
a fluid distributor (130,730) disposed below the reactor stage (110), the fluid distributor (130,730) comprising:

a liquid inlet (134, 734) to allow liquid to enter the fluid distributor (130, 730), wherein liquid from the fluid distributor (130, 730) rises up to the reactor stage (110); and
a plurality of channels (138) passing through the fluid distributor (130,730), wherein the plurality of channels (138) are connected to a gas inlet (142,754) to allow gas to enter and rise up the reactor stage (110).
2. The reactor (100,700) as claimed in claim 1, wherein the gas inlet portion (150,750) is disposed at a bottom portion of the reactor (100,700), the gas inlet (142,754) comprising at least two branches (154) to allow gas from one branch to enter one riser stage (114,710).
3. The reactor (100,700) as claimed in claim 1, comprising a calming portion (160,760) disposed above the gas inlet portion (150,750) to allow gas to spread evenly before entry into the fluid distributor (130,730).
4. The reactor (100,700) as claimed in claim 1, wherein the reactor gas outlet (128,774) is disposed on a top portion of the reactor (100,700), wherein the reactor gas outlet (128,774) is to collect product gases and effluent gases.
5. The reactor (100,700) as claimed in claim 1, wherein the fluid distributor (130,730) is one of a grid, mesh, or perforated plate.
6. The reactor (100,700) as claimed in claim 1, wherein a bottom portion of the reactor stage (110,710) is supported by the fluid distributor (130,730) and a second support (204) is disposed on a top portion of the reactor stage (110,710).
7. The reactor (100,700) as claimed in claim 6, wherein the second support (204) is one of a screen or a mesh.
8. The reactor (100,700) as claimed in claim 1, wherein hydrogen gas in fed via the gas inlet portion (150,750).
9. The reactor (100,700) as claimed in claim 1, wherein one riser stage (114,710) and one downcomer stage (118,720) is a standby reactor stage

(110), wherein no reaction occurs in the one riser stage (114,710) and downcomer stage (118,720) during operation of the reactor ((100,700).
10. The reactor (100,700) as claimed in claim 1, wherein the reactor (100,700) comprises a plurality of reactor stages (110).
11. The reactor (100,700) as claimed in claim 1, wherein the reactor (100,700) is cylindrical in shape and the plurality reactor stages (110) are arranged around a central axis of the reactor (100,700), such that each reactor stage (110) forms a quadrant of a circle.
12. The reactor (100,700) as claimed in claim 1, wherein the reactor (100,700) is cylindrical in shape and the plurality of reactor stages (110) are arranged in concentric circles around the central axis of the reactor (100,700).
13. The reactor (100,700) as claimed in claim 1, wherein inert particles are disposed on portions between the catalysts and the fluid distributor (130,730) to allow liquid to be distributed evenly before entry into the reactor stage (110).
14. The reactor (100,700) as claimed in claim 1, wherein the catalysts are one of silica, alumina, nickel, tungsten, platinum, palladium, or a combination thereof.
15. The reactor (100,700) as claimed in claim 1, wherein the catalysts size may vary from 0.8-3 mm.
16. The reactor (100,700) as claimed in claim 1, wherein liquid in the downcomer stage (118,720) acts as a heat exchanger.
17. The reactor (100,700) as claimed in claim 1, wherein the reactor (100,700) is a fixed bed reactor.
18. A method of hydrotreating a feedstock in the reactor (100,700) as claimed in claims 1 to 17.
19. The method as claimed in claim 18, wherein the reaction occurs over a temperature range of 315 – 480 ºC and a pressure range of 60-200 bar.
20. The method as claimed in claim 18, wherein the gas to oil ratio is 10-1000 Nm3/m3 and the liquid hourly space velocity is 0.5-10 hr-1.