Apparatus for dispensing particulate material

A dispensing apparatus for particulate matter which distributes the particulate matter, at substantially the same rate, uniformly across a given area. The apparatus is particularly suitable for dispensing particulate matter in a vessel having a centrally located vertical support member.

FIELD OF THE INVENTION 
The invention relates to a dispensing apparatus which distributes 
particulate matter uniformly across a given cross-sectional area. More 
particularly, this invention relates to an apparatus which is useful for 
loading catalyst particles in a reactor vessel which results in a uniform 
catalyst bed. 
BACKGROUND OF THE INVENTION 
In the past, particulate matter has been loaded into vessels or dispensed 
by what is commonly referred to as the "sock" method wherein a hopper 
having an attached hose extends to the bottom of the vessel or to the 
surface of the previously dispensed particulate matter. The hopper and 
hose are filled with particulate matter and the particulates are released 
at the bottom the hose by slowly raising the hose to thereby permit the 
particulate matter to flow through the hose. The resulting dispensed 
particulates are in the shape of a cone which, during the dispensing of 
particulates, can be distributed over the entire given area by raking. 
Commercial catalytic reaction zone vessels or reactors varying in width or 
diameter from about 1 foot to about 15 feet or more, having a length from 
about 5 feet to about 70 feet or more are loaded by the hereinabove 
described "sock" technique. One of the problems that is associated with 
loading reactors by this method is that the catalyst bed can contain 
excessive voids which can, during the use of the catalyst, bring about 
catalyst settling problems or "slumping", localized hot spots during the 
exothermic reactions of reactants and the necessity to utilize increased 
reactor volume. In addition, the sock technique requires increased times 
for loading a reactor since the hose through which the catalyst enters the 
reactor has to be continually adjusted upwardly in order to allow catalyst 
to flow. In addition to the above method, catalyst can be continually 
added through a hopper suspended above the catalyst surface which also 
results in the formation of a cone-shaped pile of catalyst upon the 
catalyst bed. As in the above method, the catalyst cone can be distributed 
over the catalyst bed by raking. 
The resulting settling of the catalyst can change the overall volume of the 
catalyst bed thereby producing damage to equipment such as thermowells 
which have been inserted into the reactor for temperature measurements. In 
addition, the settling of catalyst can reduce the surface of the catalyst 
bed to a level whereby the thermowell is not in contact with the catalyst, 
thereby not allowing the reaction temperature to be monitored during the 
course of a reaction. Excessive voids in a sock-loaded, or otherwise 
inefficiently loaded, catalyst bed cause poor gas, liquid or gas-liquid 
distribution through the bed. The maldistribution often requires decreased 
throughput or increased temperatures, since the resulting catalyst 
utilization is low and product specifications may not be met. Settling 
problems associated with sock-loaded beds may result in damage to other 
reactor internals, such as baskets, redistribution trays, catalyst 
supports and quench spargers. 
An additional problem associated with the previous loading techniques is 
that for a given reactor volume the amount of catalyst which can be 
charged is determined by the final catalyst density. Thus, a means for 
increasing the bulk density of catalyst present in a reaction zone would 
allow for increased throughput of reactants at the same severity or the 
same throughput at lower severity. Thus, more severe reaction conditions 
and/or increased throughput can be obtained for a given reaction zone 
volume if an increase in bulk density of the catalyst can be achieved. 
Subsequently, those skilled in the art have used various dispensing 
apparatus which have demonstrated improved loading of particulates into 
reactor vessels. These prior art loading devices performed reasonably well 
for vessels having open spaces without obstructions which would interfere 
with the positioning of the loading device in or above the vessel, or 
would prevent the uniform free-fall of the distributed particulate matter. 
Therefore, the known dispensing apparatus are not suitable for loading 
particulate matter into vessels which have a center-pipe located generally 
along the center line of the vessel. Those skilled in the art have sought 
to find a loading apparatus which produces a densely and evenly loaded bed 
of particulate matter in a rapid and facile manner. 
INFORMATION DISCLOSURE 
U.S. Pat. No. 3,995,753 (Millar et al) discloses an apparatus for 
dispensing particulate matter into a vessel. This apparatus is primarily 
used in an upper or top portion of the vessel and supported by a man-way. 
U.S. Pat. No. 5,209,607 (Wei et al) discloses an apparatus and process for 
feeding powder or dry solid catalyst into a flowing liquid stream. The 
apparatus includes a purging device for isolating a metering means from a 
liquid stream and process for injecting finely divided flowable powder or 
catalyst into a flowing liquid stream which in turn is fed into a reactor 
utilized for the production of polypropylene or polyolefins. 
Japanese Publication 58-6844(A) discloses an apparatus for stacking grain 
in a bin by introducing the grain in a center pipe which serves as a 
container to supply grain to a rotating element having blades which direct 
the grain in a downwardly oblique direction through upper and lower skirts 
which are fastened to the rotating element. The grain is also directed 
downwardly in a vertical direction through a tubular aperture or pipe 
which is centrally located on the bottom of the rotating element. This 
apparatus is used to store grain in a vessel while achieving an uneven top 
surface of the stored grain. The downwardly oblique flow of grain results 
in an annular accumulation of grain whereby the grain is required to roll 
downhill to ultimately fill the vessel. The centrally vertical flow of 
grain produces another pile of grain whereby the grain is also required to 
roll downhill. The apparatus fails to achieve the distribution of 
particulate matter uniformly across a given cross-sectional area to 
thereby achieve a densely and evenly loaded bed of particulate matter. In 
addition, the apparatus is unsuitable for use when the vessel has a 
centrally located and permanently mounted structure which must be 
accommodated while achieving the desired densely and evenly loaded bed of 
particulate matter. 
U.S. Pat. No. 4,300,725 (Moherek) discloses an apparatus for the 
distribution of material comprising a rotatable, vertically oriented, 
hollow delivery tube mounted for rotation about a vertical axis within a 
fixed housing and driven by means of a motor external of the tube. At its 
upper end, the tube has an inlet port for receiving particulate material 
and carrying it for distribution from its lower end by an integral system 
which includes apertures located in the tube's vertical walls and a 
deflection member or paddle at the base of the tube for radially impelling 
the material out of the tube through the apertures. The apparatus requires 
the use of a driving means because the structure of a flat horizontal 
plate in conjunction with vertical paddles would not otherwise operate to 
give a uniform, controlled distribution. 
U.S. Pat. No. 3,285,438 (Howell et al) discloses an apparatus for achieving 
uniformity of distribution of solid particles. This apparatus uses 
vertically and horizontally oriented wheel assemblies to support and 
rotate a spreader. 
SUMMARY OF THE INVENTION 
The present invention is an apparatus which is attached to a generally 
vertical support member and is able to rotate and be drawn by a motor. The 
apparatus serves as a container for particulate material while the 
particulate material flows downwardly into one or more rotating discharge 
members from which the particulate material flows and is dispensed to a 
bed located below the apparatus. 
A preferred embodiment of the present invention is an apparatus for 
dispensing particulate material which apparatus comprises a cylindrical 
bearing ring having a first bearing surface, a second bearing surface, a 
longitudinal axis and a radial axis. A container for the particulate 
material defines an annular space and incorporates a second bearing 
surface. A first roller is fixed relative to the container and is 
rotatable about the radial axis of the cylindrical bearing ring to support 
the container by contact with the first bearing surface. A second roller 
is fixed relative to the container and rotatable about the longitudinal 
axis of the cylindrical bearing ring to guide the container by contact 
with the second bearing surface of the cylindrical bearing ring. At least 
one discharge member extends downwardly from the container and in 
communication with the container. The discharge member defines an outlet 
for dispensing particulate material whereby the particulate material flows 
from the container through the discharge member and is dispensed through 
the outlet. The container is rotated relative to the bearing ring by a 
motor. 
It is therefore an object of the present invention to provide an apparatus 
and process for loading particulate material into a vessel to produce a 
bed of particulate material which possesses a high apparent bulk density 
(ABD). The use of the present invention is particularly advantageous for 
loading vessels which have a permanently mounted center pipe which is 
considered an impediment for the known loading devices but serves in an 
unexpectedly useful way when used in conjunction with the apparatus of the 
present invention. 
Another embodiment of the present invention is a method for loading 
particulate material into a vessel having a vertical longitudinally 
extended central member and distributing the particulate material, at 
substantially the same rate, uniformly across the area of the vessel by 
means of a dispensing apparatus comprising: (a) introducing the 
particulate material into the dispensing apparatus having an annular 
particle container adapted to surround said central member, defining an 
annular opening at one end for receiving particulate material into an 
upwardly directed end and an outlet at an opposite end for discharging 
particulate material below said annular opening; (b) rotating the annular 
particle container on a bearing ring encircling the central member and 
defining a bearing surface; and (c) discharging the particulate material 
through the outlet in the annular particle container into the vessel.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention may be used to dispense most types of particulate 
matter which are typically loaded into vessels and any other confined 
spaces. A particularly advantageous use of the present invention is to 
load catalyst particles into a reactor vessel which has a permanently 
mounted center pipe located almost entirely along the vertical center line 
of the reactor vessel. 
A particular advantage for the use of catalyst charged with the apparatus 
of the present invention is in various hydrocarbon conversion processes 
such as hydrogenation, reforming, hydrocracking, polymerization, 
hydrodesulfurization and dehydrogenation, for example, wherein such 
hydrocarbon conversion processes are carried out in a non-fluidized 
catalyst bed reactor, which includes fixed bed reactors and moving bed 
reactors. This invention is particularly advantageous with 
hydrodesulfurization, hydrocracking, hydrogenation and reforming 
processes. A particularly preferred application of this invention is with 
reforming and hydrogenation processes. The various process conditions of 
temperature, pressure and space velocity vary according to the process and 
such conditions include those well known to those skilled in the 
above-mentioned processes. 
An additional advantage of increased bulk density of loaded catalyst is 
that catalyst life may be extended for the same throughput and severity. 
This extension of catalyst life is a result of the tangible effect of the 
increased weight of catalyst in a fixed reactor volume as well as the less 
tangible effect of uniform gas, liquid or gas-liquid distribution which 
coincides with the more uniform voidage of a densely-loaded catalyst bed. 
Longer catalyst life results in a longer unit run length. 
Furthermore, dense loading of all reactors in an integrated refinery would 
provide a means for predicting, controlling and optimizing the occurrence 
of turnaround, based on the premise that catalyst life in each reactor of 
the refinery network would become a predictable function of tangible 
factors such as catalyst properties, throughput and operating severity. 
Intangible effects associated with maldistribution, settling and hotspots 
would be minimized by dense catalyst loading. 
In a particularly preferred embodiment, the utilization of this particle 
dispensing apparatus provides for an improved reforming process wherein a 
reforming catalyst is charged to a reactor with the apparatus of the 
present invention; then hydrogen and a dehydrogenatable organic material, 
for example, a petroleum hydrocarbon, are contacted with the reforming 
catalyst and a reformed organic material is recovered. Thus, the reforming 
process provides for allowing more throughput at the same severity for a 
given reactor vessel and for greater catalyst weight per volume of reactor 
vessel. The increase in catalyst bulk density, therefore, allows for the 
construction and use of smaller and less expensive reactor vessels for a 
given throughput. 
The apparatus of the present invention is used in one embodiment to charge 
catalyst particles to a reactor vessel in a downflow relationship to the 
reactor vessel. In general, reactor vessel sizes varying between about 1 
to about 16 feet, preferably from about 2 to about 13 feet in diameter, 
and from about 5 to about 125 feet, more preferably from about 10 to about 
75 feet in length can be charged. The rate of fill of the reactor vessel 
can be non-uniform. However, it is preferred that the rate of fill be 
uniform and that after a given rate of fill is established, this rate of 
fill be maintained while preparing the catalyst bed. The catalyst 
particles are introduced into the reactor vessel at a point such that the 
distance to the catalyst surface formed as the catalyst particles are 
introduced through a gaseous medium provides an average free fall distance 
of catalyst particles of at least about 1 foot, more preferably an average 
free fall distance from about 5 to about 125 feet and still more 
preferably from about 10 to about 70 feet. The gaseous medium in general 
is air or, depending on the catalyst, an inert medium such as nitrogen. 
Thus, in general, the catalyst particles fall individually to the catalyst 
surface as the catalyst bed is formed. The catalyst particles are 
distributed over the surface area of the catalyst bed as it is formed such 
that the catalyst surface raises at a substantially uniform rate. The 
catalyst particles are distributed in order to produce a substantially 
flat catalyst surface defined as a difference between the highest portion 
of the catalyst surface and the lowest portion of the catalyst surface 
which is less than 10 percent of the diameter of the catalyst bed, more 
preferably less than 5 percent and still more preferably less than 1 
percent. One of the most commonly used configurations utilized as vessels 
or reactors is the vertical cylinder with a circular, horizontal 
cross-section. It is also contemplated that vessels having a horizontal 
cross-section other than circular may also be loaded with the apparatus of 
the present invention. However, the apparatus of the present invention is 
highly suitable for loading particulate matter into a circular vessel 
which has an annular horizontal cross-section having a fixed center pipe. 
The apparatus of the present invention may be used in conjunction with a 
removable conduit or structure as part of a loading operation. 
The term "rate of fill" implies the rise in bed height and may be expressed 
with units of feet per hour (ft/hr). Another term, particle flux, is 
convenient to characterize the features of the loading speed and is 
defined as the pounds of catalyst particles dropped on an area of one 
square foot in one hour (lb/ft.sup.2 hr). It has been found that there is 
a certain particle flux most favorable for optimal loading of a given 
catalyst. Particle flux and rate of fill are related by the catalyst 
loaded bulk density: 
##EQU1## 
It is preferable that a flux between 100 and 1500 lb/hr-ft.sup.2 is used 
for increasing the catalyst loaded bulk density, and that more preferable 
results are obtained for most catalysts using a flux between 300 and 1000 
lb/hr-ft.sup.2. 
The above rates of fill, free fall distance, and uniform distribution of 
the catalyst within the above preferred ranges are preferred since they 
provide for approaching substantially the maximum bulk density achievable 
for a given catalyst bed. The reactor vessel sizes which are preferred are 
those reactors which, in general, are utilized in commercial processes 
such as hydrogenation, reforming and hydrocracking. 
This invention is applicable to catalyst particles which are spheres, 
pills, extrudates, crystals and cylinders, for example. In general, the 
particle diameter should not be greater than 3% of the bed diameter and, 
preferably with a diameter from about 1/64 to about 1/2 of an inch, more 
preferably from about 1/16 to about 1/4 of an inch. Catalyst particle 
diameter refers to the nominal particle dimension in the case where the 
particle is not spherical. 
A wide variety of solid catalysts may be charged to catalytic reaction 
zones with the apparatus of the present invention such as oxidation, 
hydrodesulfurization, hydrocracking, reforming and hydrogenation 
catalysts. The composition, preparation and other characteristics of such 
catalysts are well known to those skilled in the art of catalysis. 
Commercial separation zone vessels are also suitably loaded with adsorbent 
particulates in a manner utilizing the dispensing apparatus of the present 
invention. Commercial separation zone vessels vary in width or diameter 
from about 1 foot to about 15 feet or more, and have lengths from about 5 
feet to about 70 feet or more. 
The apparatus of the present invention is preferably located in an upper 
locus of the vessel to be loaded with particulate matter and, of course, 
has an overall diameter less than the vessel to be loaded. The particle 
outlet(s) preferably have a total length as measured in a radial direction 
in the range from about 2% to about 50% of the diameter of the particle 
bed. In addition, the particle outlets preferably are generally tapered 
and have an increasing width in an outwardly extending direction. The 
minimum width of the particulate outlet(s) is preferably at least about 
125% of the nominal diameter of the particles being distributed. The 
loading apparatus is preferably rotated at a speed sufficient to directly 
deposit at least some of the particles upon the outer periphery of the 
resulting bed of particles. 
In the event that the apparatus of the present invention cannot be slipped 
over one end of the conduit, it is preferable that the apparatus is built 
in two semi-circular portions that can be separated to thereby provide for 
ease of installation. 
Referring now to FIG. 1, particle dispensing apparatus 17 is particularly 
adapted to dispensing particulate matter into a vessel having a center 
pipe 12. A bearing ring 3 is removably attached to center pipe 12 in order 
to provide both horizontal and vertical support for particle dispensing 
apparatus 17 which includes annular particle container 2 which cooperates 
with shroud 9 to hold particulate matter before it is dispensed. The 
particulate matter enters particle dispensing apparatus 17 via particulate 
matter conduit 1 which is held in position by particulate matter inlet 
conduit support 16. Particle dispensing apparatus 17 is rotated around 
center pipe 12 with a drive belt 6 which is driven by sheave 5 and motor 
4. Eventually, particulate matter is dispensed via particulate matter 
distributor 11. 
Referring to FIG. 2, a bearing ring 3 is removably attached to center pipe 
12. Bearing ring 3 supports vertical load bearing casters 8 and provides 
alignment for horizontal load bearing casters 7. Vertical load bearing 
casters 8 and horizontal load bearing casters 7 are attached to shroud 9 
to provide support for particle dispensing apparatus 17. Shroud 9 is 
attached to annular particle container 2 to hold particulate matter before 
it is dispensed. Shroud 9 also seals off load bearing casters 7 and load 
bearing casters 8 to prevent entry of particles. Annular particle 
container 2 has an upper plate 13 and a lower plate 14. Particulate matter 
distributors 11 are attached to the lower locus of annular particle 
container 2. Particulate matter distributors 11 have particulate matter 
distributor slots 15 located on the trailing edge of particulate matter 
distributor 11. The particulate matter enters particulate matter inlet 
conduit 1, which is supported by particulate matter conduit support 16, in 
a downward fashion as indicated by particulate matter flow direction 10. 
The flowing particulate matter passes into a revolving annular particle 
container 2 and then flows into particulate matter distributors 11. The 
particulate matter eventually is dispersed through particulate matter 
distributor slots 15. Particle dispensing apparatus 17 is rotated around 
center pipe 12 with a drive belt 6 which is driven by sheave 5 and motor 
4. 
FIG. 3 illustrates the same apparatus which is shown in FIG. 1 and FIG. 2, 
and the reference numbers are the same as previously used. 
Referring to FIG. 4, particle dispensing apparatus 17 is shown located in 
an upper locus of vessel 19 and attached to center pipe 12. Particulate 
matter inlet conduit 1 supplies particulate matter to particle dispensing 
apparatus 17 which is rotatable and dispenses particulate matter to bed 
18. 
The foregoing description and figures clearly illustrate the advantages 
encompassed by the apparatus of the present invention and the benefits to 
be afforded with the use thereof.