SYSTEM FOR GAS-LIQUID DISTRIBUTION ON A CATALYST BED IN A
TRICKLE BEI) REACTOR
TECHNICAL FIELD
The present disclosure relates to gas-liquid distribution on a catalyst bed,
particularly, the present disclosure relates to a system and apparatus for gas-liquid
distribution on a catalyst bed in a trickle bed reactor.
BACKGROUND
In petroleum industry, three phase reactors are employed on a large scale for various
processes such as hydrodesulphurization of residual oil and gas oil, petrochemical
processing, waste treatment, biochemical and electrochemical processing. These
multi-phase reactors can be broadly classified as fixed (or packed bed) and moving
bed reactors. Example of a fixed bed reactor includes a trickle bed reactor, while
slurry reactor is a moving bed reactor.
Trickle bed reactor is a fixed bed type reactor where the liquid trickles down a
packed bed of solid catalyst and the vapor/gas phase is continuous. The fluids flow in
a co-current downward direction. Both the phases are in a plug flow mode. The
porous catalyst particles are in the form of extrudates, granules, spheres, tablets, etc.
The liquid flows down the reactor from particle to particle on the surface of the
catalyst, while the gas phase travels in the remaining void space of the flow
channels. In general, the reaction occurs between the dissolved gas and liquid phase
reactant at the interior surface of the catalyst.
Performance of a catalyst in facilitating desired reactions depends largely on the
efficiency of the distributor tray. An ideal distributor tray should provide a primary
distribution of liquid and gas, secondary distribution of liquid, high turndown ratio of
gas and liquids, resistance to fouling and maximum coverage of the catalyst bed with
uniform distribution of fluids.
Indian application no. 6/DEL/2007 discloses an apparatus for distributing down
flowing vapor or gas and liquid on a catalyst bed in a trickle bed reactor. The
apparatus disclosed in 6/DEL/2007 comprises a distributor tray with plurality of
distributor units and wherein each distributor unit is a concentric pipe comprising gas
and liquid pipe. At the bottom of every distributor unit, there is provided a secondary
distribution attachment which comprises a slotted plate and two concentric rings with
serrated bottom. The apparatus mentioned in this disclosure provides a means for
distribution of the two phases over the catalyst bed.
Another vapor/gas-liquid contacting tray is disclosed in US3410540. The contacting
tray is perforated and comprises narrow trough like downcomers spaced across the
tray for liquid to percolate to the next tray. The trough like downcomers is spaced
equally with the side walls being imperforate, providing an inactive portion of the
tray surface area. The imperforate side wall has an inlet section from where a
fraction of the two phases is received and the vapor is disengaged. The outlet section
of the imperforate side wall collects the disengaged liquid from the fraction and
discharges into subsequent trays.
Though, there are various apparatus known for gas-liquid distribution, however,
none of them are capable of providing a uniform distribution of fluid mixture with
full coverage of the catalyst bed.
SUMMARY
The present disclosure provides a system for gas-liquid distribution on a catalyst bed
in a trickle bed reactor. The present system for gas-liquid distribution comprises a
distributor tray assembly and a secondary distributor unit. The distributor tray
assembly comprises a distributor tray and a plurality of primary distributor unit and
each of the distributor unit is provided with a distributor plate. The distributor plate
comprises a central aperture and plurality of first baffle disposed on the upper
surface of the distributor plate. The distributor plate also comprises an inner ring and
outer ring having serrations and disposed on the lower surface of the distributor
plate. The secondary distributor unit disposed below the distributor tray assembly.
The secondary distributor unit comprises a plurality of perforated support plate and
one or more layers of perforated second baffles supported by the perforated support
plate.
In an embodiment of the disclosure, each primary distributor unit having two
concentric pipes mounted on the distributor tray.
In an embodiment of the disclosure, inner pipe of the two concentric pipes is a gas
pipe.
In an embodiment of the disclosure, outer pipe of the two concentric pipes is a liquid
pipe.
In an embodiment of the disclosure, the inner pipe comprises rectangular openings at
first end for gas inlet and rectangular slots at second end for gas-liquid exit. The
inner pipe is provided with a flange to prevent liquid from directly entering into
annular region formed between the inner pipe and the outer pipe. The inner pipe
comprises one or more primary holes for providing liquid entry into the inner pipe
and one or more auxiliary holes located above the primary holes to avoid flooding in
the annular region.
-3- 4
In an embodiment of the disclosure, the outer pipe comprises holes above the
distributor tray for liquid entry into the annular region formed between the inner pipe
and outer pipe.
In an embodiment of the disclosure, the outer pipe is provided with one or more
stoppers to maintain the annular region formed between the inner pipe and outer
pipe.
In an embodiment of the disclosure, the perforated support plate has a plurality of
perforations in a triangular pitch configuration.
In an embodiment of the disclosure, the perforated support plate connects the
distributor tray assembly and the perforated second baffle.
In an embodiment of the disclosure, the perforated support plate is provided with a
plurality of triangular provision for inserting the perforated triangular baffles below
the distributor tray assembly.
In an embodiment of the disclosure, the triangular provisions are provided in a
triangular pitch configuration.
In an embodiment of the disclosure, the perforated second baffle has a plurality of
perforations in a triangular pitch configuration.
In an embodiment of the disclosure, the secondary distributor unit provides a
uniform distribution of gas-liquid mixture with full coverage of the catalyst bed.
BRIEF DESCRIPTION OF FIGURES
The figures depict embodiments of the disclosure for purposes of illustration only.
One skilled in the art will readily recognize from the following description that
alternative embodiments of the structures and methods illustrated herein may be
employed without departing from the principles of the disclosure described herein.
Figure 1 illustrates a schematic view of trickle bed reactor.
Figure 2a illustrates an apparatus for gas-liquid distribution according to an
embodiment of the present disclosure. Figure 2b shows the distributor tray assembly
of the apparatus shown in figure 2a.
Figure 3 illustrates a primary distributor unit of the apparatus shown in figure 2a.
Figure 4 illustrates an inner pipe of the primary distributor unit shown in figure 3.
Figure 5 illustrates an outer pipe of the primary distributor unit shown in figure 3.
Figure 6a illustrates a distributor plate of the primary distributor unit of the apparatus
shown in figure 2a. Figure 6b and Figure 6c illustrates sectional view taken along
plane B-B and A-A respectively, of the distributor plate shown in figure 6c.
Figure 7a illustrates a secondary distributor unit of the apparatus shown in figure 2a.
Figure 7b illustrates a perforated support plate of the secondary distribution unit of
figure 7a.
DETAILED DESCRIPTION
While the embodiments in the disclosure are subject to various modifications and
alternative forms, specific embodiment thereof has been shown by way of example
in the figures and will be described below. It should be understood, however that it is
not intended to limit the disclosure to the particular forms disclosed, but on the
contrary, the disclosure is to cover all modifications, equivalents, and alternative
falling within the scope of the disclosure.
-5-6
It is to be noted that a person skilled in the art would be motivated from the
present disclosure and modify various constructions of system and its
components gas-liquid distribution in a reactor system, which may vary
from reactor to reactor. However, such modification should be construed within
the scope and spirit of the disclosure. Accordingly, the drawings show only those
specific details that are pertinent to understand the embodiments of the present
disclosure so as not to obscure the disclosure with details that will be readily
apparent to those of ordinary skill in the art having benefit of the description
herein.
The terms "comprises", "comprising", or any other variations thereof used in the
disclosure, are intended to cover a non-exclusive inclusion, such that a
apparatus, system, assembly, mechanism that comprises a list of components does
not include only those components but may include other components not
expressly listed or inherent to such system, or assembly, or apparatus. In other
words, one or more elements in a system or device proceeded by "comprises... a"
does not, without more constraints, preclude the existence of other elements or
additional elements in the system or apparatus.
The following paragraphs describe the system and apparatus of the present disclosure
with reference to Figures 1 to 7. In the Figures the same element or elements which
have same functions are indicated by the same reference signs.
The terms such as upward, downward, vertical, horizontal, lower and upper used in
the description are referred with respect to particular orientation of the system as
shown in the figures of the present disclosure. Hence, such words should not be
construed as limitation to the present disclosure, as the same may be varied
depending on the orientation of the system.
-fr
Figure 1 shows a reactor column (2) with a system for gas-liquid distribution on a
catalyst bed (3) according to an embodiment of the present disclosure. The reactor
(2) shown in Figure 1 may be but not exclusively a trickle bed reactor. As shown in
Figure 1, the reactor (2) comprises a vertical reactor column having an inlet (4)
located at top end of the reactor column (2) for co-currently supplying gas-liquid
mixture in the reactor column (2). The reactor column (2) comprises an outlet (5) at
bottom end of the reactor column (2) for obtaining the reaction products. The gas and
liquid phases are pre-mixed and provided sufficient time for the mass transfer to
occur before supplying to the reactor column (2) through the inlet (4). The gas and
liquid phases interact with each other and form an equilibrium mixture. At this
equilibrium state, no further mass transfer occurs between gas and liquid phases that
saturates the feed mixture. The gas-liquid mixture which is at equilibrium hereinafter
referred as the 'gas-liquid mixture'.
In an embodiment, a nozzle or spray (not shown in Figures) may be provided at the

We Claim:
1. A system for gas-liquid distribution on a catalyst bed in a trickle bed reactor,
comprising:
a distributor tray assembly comprising a distributor tray and a plurality of
primary distributor unit and each of the distributor unit is provided with a
distributor plate; the distributor plate comprising:
a. a central aperture,
b. plurality of first baffle disposed on the upper surface of the
distributor plate,
c. inner ring and outer ring having serrations and disposed on the
lower surface of the distributor plate.
a secondary distributor unit disposed below the distributor tray, comprising a
plurality of perforated support plate and one or more layers of perforated
second baffles supported by the perforated support plate.
2. The system as claimed in claim 1, wherein each primary distributor unit
having two concentric pipes mounted on the distributor tray.
3. The system as claimed in claim 2, wherein inner pipe of the two concentric
pipes is a gas pipe.
4. The system as claimed in claim 2, wherein outer pipe of the two concentric
pipes is a liquid pipe.
5. The system as claimed in claim 3, wherein the inner pipe comprises:
a. rectangular openings at first end for gas inlet,
b. flange to prevent liquid from directly entering into annular region
formed between the inner pipe and the outer pipe,
c. rectangular slots at second end for gas-liquid exit,
d. primary holes for providing liquid entry into the inner pipe,
e. auxiliary holes located above the primary holes to avoid flooding in
the annular region.
6. The system as claimed in claim 4, wherein the outer pipe comprises holes
above the distributor tray for liquid entry into the annular region formed
between the inner pipe and outer pipe.
7. The system as claimed in claims 3 and 4, wherein the outer pipe is provided
with one or more stoppers to maintain the annular region formed between the
inner pipe and outer pipe.
8. The system as claimed in claim 1, wherein the perforated support plate has a
plurality of perforations in a triangular pitch configuration.
9. The system as claimed in claim 8, wherein the perforated support plate
connects the distributor tray assembly and the perforated second baffle.
10. The system as claimed in claim 9, wherein the perforated support plate is
provided with a plurality of triangular provision for inserting the perforated
second baffles below the distributor tray assembly.
11. The system as claimed in claim 10, wherein the triangular provisions are
provided in a triangular pitch configuration.
12. The system as claimed in claim 1, wherein the perforated second baffle has a
plurality of perforations in a triangular pitch configuration.
13. The system as claimed in claim 1, wherein the secondary distributor unit
provides a uniform distribution of gas-liquid mixture with full coverage of
the catalyst bed.