Note: Descriptions are shown in the official language in which they were submitted.
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Loading device for loading particles, method for loading
particles using a loading device
The invention relates to a loading device for loading
particles through the entries of an array of tubes, the
device comprising of a plate having a pattern of loading
holes.
In refineries and chemical industry in general, an
assembly of tubes is often applied, in particular in heat
exchangers or reactors that require heating or cooling of a
fluid flowing through the tubes. The tubes are in cross-
section relatively small (e.g. 20-50 mm) while their length
is relatively large (1.5 to 20 metres). The tube assembly is
normally mounted in a vessel, wherein the tubes are held in
a parallel arrangement to each other, the axes of the tubes
forming a two-dimensional array when the assembly is seen
along the axis of the tubes. The tubes are for instance
filled with a bed of particles that are involved in
converting compounds that are led through the bed of
particles.
Loading of tubes with solid particles in such tube
assembly is done by feeding the particles into the top
opening of the tubes. The particles fall down the tube until
stopped by a device or already present particle bed.
The individual tubes have to be loaded with equal
amounts of particles with respect to volume, loading height,
mass and porosity. Identical loading is required because the
flow of fluid compounds through each tube as well as the
residence time of the fluid compounds in each tube of the
assembly should be equal. Most commonly, the particles are a
solid form of a catalyst on a carrier, which influences the
reaction of fluid compounds that are led through the tubes.
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The loading or re-loading of the multitude of narrow
and elongated reactor tubes with catalyst, the particles of
which are generally not very much smaller than the inner
diameter of the tubes, is difficult and time-consuming. An
even distribution of the catalyst particles inside each tube
and between all tubes is in this case very important but
difficult to achieve. During loading it is essential that
the number of particles entering the reactor tube at the
same time, multiplied by their greatest dimension, be small
enough in relation to the internal diameter of the reactor
tube so as to avoid the condition known as "bridging".
"Bridging" occurs when several particles enter and fall down
the tube simultaneously, wedge together and effectively clog
the inside of the tube - resulting in unevenly and
incompletely loaded tubes. When loading the elongated
reactor tubes described above, it is best to ensure that the
particles enter these tubes one by one.
A further requirement, in particular when high reaction
temperatures occur in the tubes, is that a small upper
portion of each reactor tube is kept free of catalyst. This
upper portion which should be kept unloaded, is also
referred to as 'outage'.
In practice, the particles may be supplied in different
containers such as tube packs or big bags. A tube pack
normally contains the content of particles for one tube; the
big bag contains the content of many tubes, in which the
maximum amount of particles is constrained by handling and
particle strength limitations.
From EP 0963785 A, a loading device for an array of tubes is
known which is built up from a multitude of elementary
loading devices consisting of one loading plate having one
loading hole and a small conduit connected to the loading
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hole. The conduit serves as an insert for positioning the
loading plate on top of an entry of a tube. The elementary
plates are formed in such a way that neighboring plates can
be positioned on adjacent tube entries so that the outside
edges of all plates butt to each other. As a result, the
individual plates together make a closed surface and thereby
cover the array of tubes on which the devices are
positioned. The result may be compared to the way tiles are
arranged together in order to cover a floor. When the plates
are in covering position, the particles may be loaded on the
closed surface of the combined plates, and be swept over the
holes in order to load the tubes.
In a variant, the plates may be dimensioned such that
their surfaces leave some small inter-plates space for
accommodating dust, in order to avoid dust entering the
tubes via the loading holes. Dust may be present in the
particles as supplied, or may be formed during the process
of loading the particles in the tubes.
The method using devices consisting of a loading plate
and a loading hole, are referred to as 'orifice loading'.
The word 'orifice' refers to the specific opening of the
hole which is less than the opening of the tube to be
filled.
When loading particles in an array of tubes, the
following two techniques are widely applied to create an
outage, which may be also applied in combination:
1. Vacuuming particles from the top entry of a tube to the
required outage, and
2. Use of a loading device with a filling tube or conduit
which is inserted in the tube that has to be loaded.
The first technique 1) puts a hose connected to a
vacuum system in the top of the tube with particles. The
particles near to the hose are sucked into the hose. The
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hose is moved downwards and removes particles until the
required outage has been reached.
The second technique 2) uses a loading device with a
filling tube or conduit connected to the loading hole, which
conduit is inserted into the tube of the array to be loaded.
For clarity's sake, this filling tube or conduit, should be
distinguished from the tubes of the array, which may in this
description be called vessel tubes in order to distinguish
between the two types of tubes. The vessel tubes may also be
called reactor tubes in this description.
The filling tube of such device has a smaller outer
diameter than the inner diameter of the vessel tube and an
inner diameter more than the diameter of the loading hole.
After loading the particles up to plate level using such
device, the device is removed so that the particles left
over in the filling tube drop into the tube. As the inner
volume of the filling tube is smaller than the inner volume
of the entry of the vessel tube over the length of the
filling tube inserted, an outage is created automatically
which has a volume corresponding to the difference in inner
volume between the filling tube and the vessel tube.
The prior art EP 963785 A, shows in its example a
combination of techniques 1 and 2 in order to create an
outage.
The invention aims at improving known loading devices
in view of:
identical loading of particles in the tubes,
an efficient loading process,
reduction of dust entering the tubes,
creating an outage.
The issue of identical loading has been explained above, and
relates to a uniform filling of the tubes with uniform
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particles, in order to have identical beds of particles in
the tubes, so that the reaction conditions as well as
flowing conditions inside the beds of particles are similar.
Reducing the time to load particles is relevant for two
5 reasons. The vessel with its vessel tubes has a high capital
charge because of the cost of construction and installation
of such vessel. During normal operations, products with high
added value are produced in the vessel, which cannot be
produced during loading of particles. Also equipment and
manpower to load the particles have a high hourly cost rate.
Abrasion of the particles during manufacturing,
transport and loading cause the particles to be of smaller
size than meant to be loaded in the vessel tube and the
formation of dust. This is very undesirable because the
small particles and dust change the fluid transport
properties of the medium flowing through the reactor tubes
and cause problems outside the vessel tubes. Further, the
dust is a threat to health when inhaled. Outside a reactor
tube the dust is still active and causes undesired reactions
at undesired locations. Thus, abrasion and dust formation
has to be prevented or minimized and the inevitable products
of abrasion and dust formation have to be separated from the
particles.
The creation of an outage is a general requirement
dependent of the reactions taking place in the tubes, as
explained above.
In a first aspect the invention therefore relates to a
loading device according to the appended claims.
Specifically, the invention relates to a loading device
for loading particles through the entries of an array of
tubes, the device comprising of a plate having a pattern of
loading holes, which pattern corresponds to the array of
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tube entries, the opening of the loading holes being smaller
in size than the opening of the tube entries and larger in
size than the particles to be loaded, characterized in that
the plate comprises sieving means between the loading holes,
the sieving means comprising sieving openings.
Such a loading device achieves a coverage of a large
array of tubes, while achieving an efficient dust removal at
the stage where particles are loaded in the holes by moving
an amount of particles over the plates. In this way, no
elementary plates have to be positioned in an exact manner
to each other in order to achieve a closed surface, possibly
with inter-plate spaces for dust removal. Effectively, the
application of the loading device onto the array of tubes is
less time-consuming.
The loading device thus achieves a more efficient
process for loading particles in an array of tubes, while
providing an optimal removal of dust particles so that the
loading of the tubes is primarily bound to the particles
intended to be loaded inside the tube. This enhances the
identical loading of tubes and does not compromise the
flowing characteristics inside the tube filled with a bed of
particles.
The loading hole has a diameter that allows particles
to pass through them, while it is smaller than the entry of
the tube so that the bridging effect is reduced. An
appropriate ratio is that the diameter is 1.2 to 3.0 times
the greatest dimension of the particles to be loaded. Such
ratio allows a more or less individual dropping of particles
through the hole into the tube, which reduces the bridging
risk inside the tube.
Preferably, in the loading device according to the
invention, the sieving openings are smaller than the
particles to be loaded. This secures that no particles will
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accidentally be lost through the sieving openings, so that
they do not have to be recovered from the space between the
tube entries.
Advantageously, in the loading device according to the
invention, the sieving means are made of wires, rods, gauze
or screens. These materials have proven adequate for
achieving the intended dust removal, as well as moving
particles over their surface into the loading holes.
With further preference, in the loading device
according to invention, the sieving means are detachable as
a separate entity from the plate which has openings between
the loading holes which are larger than the particles to be
loaded. This loading device gives the opportunity to switch
to different sieving means with different size of openings,
when the particles to be loaded are changed. The plate with
openings can be kept mounted on the array of tubes, while
the sieving means is removed from the top and changed by
another type. This makes the loading process more efficient.
Moreover, the user can use one plate with holes, while the
dust removing properties from the sieving means can be
changed, which reduces costs. To make sure that the sieving
openings are not blocked by the underlying plate, the plate
has openings between the loading holes that are relatively
large, i.e. larger than the particles to be loaded.
In a further preferred embodiment, the loading device
according to the invention, comprises a grid of bars, rods
or wires movable over the plate and its sieving means, the
grid having a pitch similar to the array of loading holes
and each cell of the grid encloses an open surface which is
larger in size than the loading hole. This grid functions as
a tool for moving the particles loaded on the plate into the
loading holes. By a simple to and fro movement of the grid,
the particles are slid into the loading holes. Any particle
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bridges formed above the loading hole and blocking the
entrance, are removed by the grid's movement. The grid
allows a highly efficient movement of particles into the
loading holes. In the process the particles are less subject
to shearing forces as in known devices. This reduces the
abrasion or breakage of particles, and thus reduces the
formation of dust and secures a more uniform size of the
particles that are loaded.
Preferably, in the invention, a friction reducing
material is provided at the side of the grid that is
directed towards the plate and its sieving means. This
reduces shearing forces when moving the grid over the plate,
and reduces the possibility of particles being trapped
between the grid and the plate, which may be detrimental to
the advantages described.
With further preference, the loading device according
to the invention, comprises above it a distribution plate
which has openings larger than the particles to be loaded.
In the process of loading particles, a distribution plate is
an expedient tool to distribute evenly a large amount of
particles over the whole loading plate. This reduces the
time for loading and enhances the identical loading in the
tubes.
In a further preferred embodiment, the loading device
according to the invention, comprises a conduit connected to
the loading hole, the outer diameter of the conduit being
smaller than the inner diameter of the entry of the tube so
that the conduit is insertable in the tube, while the inner
diameter of the conduit being larger than or equal to the
opening of the loading hole. A conduit achieves a way of
creating an outage after the loading holes are completely
filled up to the loading plates. The relative dimensions are
taken such that the risk of bridging is small, while the
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conduit fits inside the entry of the tube so that their
position is secured. The length and inner volume of the
conduit determines the amount of outage created after the
loading device is removed from the array of tubes.
Preferably the conduit is provided with closing means
for closing the conduit to prevent particles that remain in
the tube after loading, to fall out of the conduit when the
loading plate is taken away from the tube. Such a loading
device is thus capable of filling the tubes to the exact
outage as desired.
Alternatively, the loading device according to the
invention, includes a vacuum hose connectable to the loading
hole. The vacuum is used to prevent remaining particles in
the conduit, from falling in the tube. By connecting a
vacuum hose to the loading hole, all particles present in
the conduit may be removed from the conduit. As such, the
outage created is then directly determined by the length by
which the conduit is inserted inside the tube entry.
Preferably, side ventilation ports are provided in the
conduit for reducing the risk of bridging of particles
inside the conduit when the vacuum hose is used to remove
them. The side ventilation ports allow the vacuum stream to
suck in air from a different direction than solely along the
direction of the conduit. More preferable are side
ventilation ports which are automatically in closed position
and open when the tube diameter is filled with particles. It
is only in that situation that the vacuum stream should have
an extra direction, so that in other situations there is no
loss of vacuum over the side ventilation ports.
In a further variant of the invention, the loading
device comprises a sieve at the end of the hose which is
connectable to the conduit, the sieve having openings
smaller than the particles present in the conduit. This
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construction of the vacuum hose allows the vacuum to suck
the particles up to the sieve, without removing them from
the conduit. In this state the plate and conduit can be
removed while applying the vacuum, so that the particles are
5 retained in the conduit. After removal, the application of
vacuum is stopped, so that the particles will dislodge from
the conduit, and can be accumulated in an appropriate
container.
Preferably, the loading device according to the
10 invention, comprises the loading holes which are provided
with a closing means for closing the hole so that no
particles can pass the loading hole, and preferably a sensor
for detecting the loaded volume of particles inside the
tube, which sensor controls the closing means when a
predetermined volume of particles is loaded.
The closing means are preferably a lid closing fully or
partially the loading hole, so that it functions as a stop
that blocks the passage of particles. The sensor may be
provided in the tube to be loaded or on the loading device.
The sensor controls the closing means by force of an
actuator. As such, an outage can be created in the tube
which is determined by the settings of the sensor, and takes
away the need of applying vacuum in the tube to remove
particles, or a loading plate with a conduit.
Preferably, the loading device according to the
invention, comprises a closing means which is a movable stop
which is conically shaped. The nature of such stop is
further explained below in regard of the appended figures.
In a second aspect, the invention relates to a loading
device for loading particles through the entries of an array
of tubes, the device comprising a plate having one or more
loading holes, the opening of the loading hole being smaller
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in size than the opening of a tube entry and larger in size
than the particles to be loaded, and a conduit connected to
the loading hole, the outer diameter of the conduit being
smaller than the inner diameter of the entry of the tube so
that the conduit is insertable in the tube, and the inner
diameter of the conduit being larger than or equal to the
opening of the loading hole, and a vacuum hose that is
connectable to the loading hole. The vacuum can be used for
removing particle from the conduit with vacuum or for
withholding particles present in the conduit from entering
the tube of the array.
As explained above, the vacuum hose achieves that in
the tube an outage is created in a new and more effective
way which can correspond to the length of the conduit that
is inserted in the tube. This advantage applies also to
elementary loading devices consisting of one plate and one
loading hole.
An alternative comprised by this second aspect of the
invention, is the variant wherein the loading plate has more
than one loading hole. Herein, the loading holes have a
pattern which corresponds to the array of tube entries, and
are provided with conduits likewise.
Preferably, the loading device according to the
invention, comprises a sieve at the end of the hose which is
connectable to the conduit, the sieve having openings
smaller than the particles present in the conduit. Such a
device is capable of withholding particles present in the
conduit from entering the tube of the array, under the
condition that the device is removed from the tube while the
vacuum is still applied. The advantages described above
apply also to elementary loading devices consisting of one
plate and one loading hole.
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In particular the advantages relating to using a vacuum
are a further aspect of the invention which relates to a
method for loading particles through the entries of an array
of tubes, using a loading device comprising a plate having a
loading hole and a conduit connected to the loading hole,
which device is inserted into the entry of a tube, loading
particles through the loading hole, and connecting a vacuum
hose to the loading hole thereby applying a vacuum to the
conduit.
As stated above, it is advantageous to use side
ventilation ports provided in the conduit, and even more
preferable are side ventilation ports which are
automatically in closed position and open when the tube
diameter is filled with particles.
In a third aspect, the invention relates to a method
for loading particles through the entries of an array of
tubes, using a loading device comprising a plate having one
or more loading holes, and a conduit connected to the
loading hole, which device is inserted into the entry of a
tube, loading particles through the loading hole, and
connecting a vacuum hose to the loading hole thereby
applying a vacuum to the conduit so that particles remaining
in the conduit are removed.
The vacuum hose achieves that in the tube an outage is
created in a new and more effective way which can correspond
to the length of the conduit that is inserted in the tube.
Alternatively, the method of the invention relates to a
method for loading particles through the entries of an array
of tubes, using a loading device comprising a plate having a
loading hole and a conduit connected to the loading hole,
which device is inserted into the entry of a tube, loading
particles through the loading hole, and connecting a vacuum
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hose to the loading hole thereby applying a vacuum to the
conduit, wherein the vacuum hose that is connected to the
conduit comprises a sieve at the end of the hose, the sieve
having openings smaller than the particles present in the
conduit, so that particles remaining in the conduit are
drawn towards the sieve under vacuum, with the additional
step of removing the loading device while the vacuum is
applied.
The above mentioned advantages apply analogously.
In a further aspect, the invention relates to an
assembly of a loading device for loading particles through
the entries of an array of tubes and said array of tubes,
wherein the device comprises a plate having one or more
loading holes, the opening of the loading hole being smaller
in size than the opening of a tube entry and larger in size
than the particles to be loaded, and each tube comprises a
sensor for detecting the loading volume in the tubes, and a
closing means for closing the path of particles that enter
the tube, wherein the sensor controls the closing means.
As explained above, the assembly achieves that in the
tube an outage is created in a new and effective way, which
is independent of known measures such as vacuuming off the
tube itself, or by using a loading plate having conduits at
the loading holes. This advantage applies also to elementary
loading devices consisting of one plate and one loading
hole.
An alternative comprised by this further aspect of the
invention, is the variant wherein the loading plate has more
than one loading hole. Herein, the loading holes have a
pattern which corresponds to the array of tube entries, and
are provided with conduits likewise.
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The closing means is for instance provided on top of
the entry end of the tube, or at the loading hole of the
plate.
Preferably in the assembly according to the invention,
said sensor controls the closing means when a predetermined
volume of particles is loaded. With particular preference,
the sensor is an electrical switch activated by the loaded
particles. The nature of such sensor is further explained
below in regard of the appended figures.
lo The invention may further be provided with additional
features such as a telescopic built up of the conduit, and/or
a rod connected to a closing means, as featured in dependent
claims.
In another aspect, the invention relates to a loading
device for loading particles through tube entries of an array
of tubes, the device comprising a plate having a pattern of
loading holes, which pattern corresponds to the array of tube
entries, the opening of the loading holes being smaller in
size than the opening of the tube entries and larger in size
than the particles to be loaded, characterized in that the
plate comprises sieving means between the loading holes, the
sieving means comprising sieving openings, wherein the
sieving means are detachable as a separate entity from the
plate, and wherein the plate has openings between the loading
holes which are larger than the particles to be loaded.
Brief Description of the Drawings
Figure 1 shows a cross-sectional view of an embodiment
of the loading device of the present application, wherein the
loading device has a circular loading plate with a circular
loading hole.
Figure 2 shows a top plan view of sieving means
according to an embodiment of the present application.
Figure 3 shows a top plan view of a grid according to
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an embodiment of the present application.
Figure 4 shows a cross-sectional view of a complete
constellation of the loading device according to an
embodiment of the present application.
Figure 5 shows a cross-sectional side view of a loading
device having a filling tube or conduit connected to a
loading plate near a loading hole, according to an embodiment
of the present application.
Figure 6 shows a cross-sectional side view of the
loading device shown in Figure 5, wherein particles are
loaded in a vessel tube and some particles remain in the
conduit, according to an embodiment of the present
application.
Figure 7 shows a cross-sectional side view of the
loading device shown in Figure 5, wherein a closing means is
shown in the closed position, according to an embodiment of
the present application.
Figure 8 shows an exemplary use of a loading device
according to an embodiment of the present application.
Figure 9 shows a top plan view of a loading plate,
according to an embodiment of the present application.
Figure 10 shows a side view of a loading plate of the
present application with an adapted conduit having side
ventilation ports distributed over its length, according to
an embodiment of the present application.
Figures 10a and 10b show cross-sectional top views of
the adapted conduit of Figure 10, according to an embodiment
of the present application.
Figure 11 shows a cross-sectional top view of an
adapted vessel tube having a sensor mounted along the inner
diameter of the vessel tube for detecting the loaded volume
of particles inside the tube, according to an embodiment of
the present application.
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Detailed Description
The invention will be further explained by a
description of the appended figures, wherein corresponding
features are referred to by the same reference numbers where
appropriate.
Figure 1 shows a cross section of an elementary loading
device 1 which is based on a circular loading plate 4 with a
circular loading hole 6. The loading plate 4 is provided with
short extensions 8, that function as a guiding means for
placing the device 1 axially centered in a tube. The loading
hole 6 has a diameter of 17 mm and the outer diameter of the
loading plate 4 is 44 mm.
Under the plate a support tube might be provided of 30
mm length having a diameter larger than the top parts of
tubes sticking out of a vessel. The support tube is
especially useful to create a uniform distance between the
vessel and the plates, so that the plates are at an even
height.
Between the loading plates sieving means such as wires,
rods or screens are mounted in such a way that the maximum
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distance or opening between the wires, rods or screens and
the loading plates or between the wires or rods or wires of
the screens is less than or equal to the minimum length
dimension of the particles that are allowed in the vessel
5 tube. In other words the particles with a size less than
allowed in the vessel tube fall through the openings between
the rods, wires, screen or plate. Via these opening
particles and particle dust are removed that are not allowed
in the assembly of tubes.
10 Figure 2 shows an example of the sieving means
according to the invention. The sieving means are connected
to each other and possibly to the loading plate. Figure 2
depicts a plate having an array of large holes 22 and small
slots 24 between the holes 22. The large holes are meant to
15 surround the loading plates 4 when they are positioned on an
array of vessel tubes. The slots 24 function as sieving
means for removing dust and small particles. The large holes
22 are positioned according to the array of tubes of the
vessel, and butt to the circumference of loading plates 1 as
depicted in figure 1. The plate 20 is also named a cover
plate in this description and is connectable to the loading
plates 1. The connection can be removable, clipped or fixed.
The plate may leave some small space between the loading
plates 1 and the large holes 22, wherein the small space
functions as a further sieving means.
The holes may be provided with support tubes (not
shown) for the same reasons as mentioned above.
Figure 3 shows an example of a grid 30 which follows
the same pattern as the cover plate 20 of figure 2.
Effectively, the pitch 32 of the grid 30 is the same as for
the array of tubes, which is similar to the pattern of the
large holes of the cover plate 20. In order to move
particles to the loading hole the grid is moved to and fro
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over the surface of an assembly of loading plates 1 and the
cover plate 20. The particles are slid into the loading
holes. Possible particle bridges formed above the loading
holes, and blocking these, are thereby removed. Below the
stiff grid soft and flexible material can be mounted to ease
sliding.
Figure 4 shows schematically a cross-section view of a
complete constellation of the loading device according to
the invention, comprising the above described features. A
particle supply hose and distributor is indicated as 42. A
distribution screen is identified as 44. In the screen,
impingement plates or cones could be installed corresponding
with the array of vessel tube openings. A grid to move
particles to the loading holes is present as 30. A cover
plate of sieving means with slots is present as 20. The
loading plates in this drawing are referred to as 1. For
clarity reasons the devices identified as are drawn above
each other. When in use, the top surface of the loading
plates 1 and the top surface of the cover plate 20 with
slots are at the same level and connected to each other. A
part of an array of tubes is drawn as 46. When in use, the
loading plates 1 will contact the tubes 46 during the
loading process instead of 'floating' above each other.
In addition to figure 4, the following is to be
observed: When unloading the (transport) container of
particles, the dust coming with the particles and the
particles of a size smaller than allowed in the vessel tubes
are separated by sieving or blowing (sifting). With a
controlled flow the particles are deposited on a
distribution screen above the section with loading and cover
plates to create a layer upon the loading device with a
thickness of at maximum a few particles. In the screen
impingement plates can be mounted corresponding with the
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opening of the vessel tubes. These impingement plates
prevent small particles and particle dust to enter the tubes
directly. These small particles and dust are caught in the
area between the tubes. The distribution screen is shaken to
create an even layer. The openings in the distribution
screen are larger than the particle diameter and therefore
the particles fall as a rain on the wires, rods, screen or
cover plate.
Instead of the distribution screen, a frame can be used
with impingement plates that are mounted in the frame at
positions corresponding with the opening of the vessel tubes
in case no distribution of particles is required. In order
to promote the flow of particles the impingement plates can
be replaced by cones with a bottom diameter equal to the
diameter of the vessel tubes.
Figure 5 shows a loading device 1 having a filling tube
or conduit 72 connected to the loading plate 4 near the
loading hole 6. The conduit 72 is inserted inside a vessel
tube 74 which is part of an array of tubes 46. In case a
variable outage is required, the filling tube 72 is
constructed from two or more tubes that are connected
telescopically. At the lower end of the filling tube 72 a
movable blocking device 76 is mounted that works as a
closing means for the lower end of the conduit 72.
As depicted in figure 6, particles 80 are loaded in the
vessel tube 74, while some particles remain in conduit 72.
Figure 7 shows the blocking device 76 in closing
position at the end of conduit 72, while the whole loading
device is lifted from the vessel tube 74. Most effective and
efficient is to provide a blocking device below the loading
plate. When the required outage is reached the hole is
closed.
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The closing device is actuated by a sensor that
measures the loading height of the particles or that is
mounted at the loading height (where outage should start) in
the vessel tube and senses the particles at that height. In
this case no filling tube is required that has to be
installed, removed and requires further time consuming
handling.
For the sensor the difference in physical properties
between air and particles can be used. Some particles have
electrical conductivity much higher than air which acts as
an isolator for electricity. The electrical current can
actuate the closing valve. Or in case pneumatic control is
used the particles close an escape opening of pneumatic air
that will increase in pressure and actuate the closing
valve. Also capacitive sensors or inductive sensors can be
used. The preferred solution is an electrical switch that is
actuated by the particles when the particles have been
loaded up to the required loading height.
Figure 8 shows a preferred use of the loading device
according to the invention. A vacuum hose 120 - only the end
of the hose is depicted - is attached to a loading plate 4
with filling tube 72. The vacuum hose can be put directly on
the loading plate or can have a conical end that is put into
the loading hole of the loading plate. Removing the particle
by vacuum to obtain the required outage can be done in two
ways:
- vacuuming off the particles from the filling tube when the
filling tube is still the vessel tube;
- retaining the particles under vacuum in the filling tube
and take the filling tube with particle out of the vessel
tube.
In figure 8, the vacuum is used to retain (secure) the
particles in the filling tube 72. For that reason, a sieve
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122 is provided inside the end of the hose 120. The
particles that remained in the conduit after loading, are
drawn towards the screen by the vacuum. Because of the
vacuum the particles are retained inside the filling tube,
when the plate is removed from the vessel tube while still
applying the vacuum. After removal of the device under
vacuum, the vacuum is stopped and the particles are dropped
at an appropriate location.
When vacuuming particles from the filling tube (this
step is not depicted) it is preferable that the filling tube
has an inner diameter, equal to or slightly more than the
diameter of the loading hole. In this way when removing
particles from the conduit by vacuum, the risk of
obstruction of the particle flow at the loading hole by
particle bridges is minimized. The particles in the filling
tube are moved upward by the vacuum. It is possible to
vacuum more than one tube at the same time. After that the
loading plate and empty filling tube are removed from the
vessel tube leaving an appropriate outage. Because the
filling tubes are empty many loading plates and filling
tubes can be taken out of the vessel tubes at the same time.
Figure 9 shows an alternative loading plate 140
according to the invention, comprising an array of loading
plates with loading holes 6 connected to each other by
connecting platelets 144. The loading plate 140 may be
combined with a cover plate, for instance a cover plate as
shown in figure 2. The cover plate may alternatively be a
screen having sieving openings smaller than the particles to
be loaded and having an array of holes that correspond in
size and position to the loading holes 6 of the plate 140.
Figure 10 shows a loading plate 4 with an adapted
conduit 72 having side ventilation ports 160 distributed
over its length according to the invention. The ports 160
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are opened by movement of a closing lid 162 with a short
gliding arm 164, under the pressure of particles in the
filling tube (see cross section figure 10a). The closing
lids 162 are normally in closed position over the side
5 ventilation ports 160 when the particles are absent and the
conduit is put under vacuum (figure 10b). The closed
position is actuated by use of vacuum , while under pressure
of particles the lid is moved open so that the ports 160 are
opened.
10 Figure 11 shows an adapted vessel tube 170 in cross-
section, having a sensor at the level where the outage has
to start. The sensor comprises a bow-like member 172 mounted
along the inner diameter of the vessel tube at a small
distance therefrom. The member 172 is movable in the
15 direction of the inner vessel tube surface by particles that
fill the inside of the vessel tube. When during loading the
particles reach the height at which the bow is mounted, the
particles push the bow against the inner tube surface.
Subsequently, two electrical connectors 174 are connected,
20 which close a low voltage circuit with a solenoid 176, that
controls an actuator (not depicted) which closes the loading
hole or the entry of the tube.
The use in practice of the loading device for loading
an array of tubes is further explained by the following
examples of the invention.
The examples given relate to a loading of particles in tube
assemblies in vessels as widely used in industry and where
the particles are 8 mm nominal diameter catalyst particles
and the vessel is an ethylene-oxide reactor with 9000
reactor tubes of 39 mm inner tube diameter vertically
assembled in a bottom and top tube sheet. The length of the
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vessel tubes is 10 m. In the bottom end of the tube a spring
is installed to prevent catalyst to leave the reactor tube
during filling and operation of the reactor. The information
on catalyst and reactor is summarized in the following
table:
reactor tubes number 9000
tube length 10 m
particles per tube 10 kg
inner diameter 0.039 m
catalyst nominal particle length 0.008 m
catalyst maximum particle length 0.009 m
catalyst minimum particle length 0.002 m
catalyst in big bag 900 kg
The catalyst is loaded for all examples given below via one
or more loading plates with one or more loading holes.
Unless mentioned differently at the description of the
example on the top of each vessel tube a loading plate of 44
mm diameter is axially centered on the tube. The plate has a
loading hole of respectively 17 or 20 mm in the different
examples, through which at maximum two particles drop at the
same time into the tube. Figure 1 shows an example of the
plate with an loading hole of 17 mm.
1. Plates assembled in circle segments
9000 plates are mounted in 9 screen segments in that
way that holes in the screen correspond with the loading
holes. The 9 segments are installed in 1 hour in such a way
that each reactor tube is covered by one plate with a
loading hole with corresponding centres.
Every six minutes a big bag is unloaded on the plates
and screen assembly and swept manually via the loading holes
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into the reactor tubes until the catalyst reaches the plate
after having filled the reactor tube.
After 14 hours all 9000 tubes have been loaded. The
plates and screen assemblies are removed in 2 hours while
simultaneously vacuuming the surface between the reactor
tubes.
If required an outage can be created by vacuuming the
particles from the top of the tube to the desired outage.
2. Integrated loading and cover plate without outage.
A cover plate with slots of 2 mm, integrated with an
array of 90 loading holes of 20 mm diameter, is put on 90
reactor tubes. The slots in the cover plate are located at
the surface outside the vessel tube openings.
A grid of small bars as shown in figure 3 is put on the
integrated loading and cover plate. On the four sides of the
grid 40mm high partitions are mounted.
Catalyst from a big bag containing 900kg of catalyst is
fed to a vibrating screen outside the reactor. The screen
removes dust and transports 90kg of catalyst per minute to a
hose with an outlet device that evenly spreads the catalyst
on a stiff distribution screen with openings of 16mm. The
distribution screen has the rhombus shape of figures 2 and 3
with partitions around the screen. An even layer of about 2
particles thick is created on the screen by shaking the
screen. Through the openings of the screen the particles
rain on the integrated loading and cover plate. The grid of
stiff straight wires slides the catalyst in the loading
holes by moving the stiff wires to and from the loading
holes.
Simultaneously a second filling assembly is installed
on 90 other reactor tubes. After 10 minutes the first 90
tubes have been filled with 10 kg catalyst each and the big
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bag is empty. The small amount of surplus catalyst in the
first filling assembly is vacuumed and recycled to the
vibrating screen outside the reactor. The first filling
assembly is moved to another set of 90 vessel tubes.
Catalyst is vacuumed from the reactor tubes to the required
outage and recycled to the vibrating screen outside the
reactor. Particle dust and small particles are vacuumed from
between the vessel tubes and are disposed. Thereafter the 90
vessel tubes are covered with one plate to protect the
content of the tubes.
This procedure is repeated until all 9000 vessel tubes
are loaded with 10kg particles. More than one filling
assembly can be used at the same time. At the outer edge of
the tube sheet different shapes of filling assemblies are
required to fit the shape of the reactor.
In the example above about 20% of the inevitable
products of abrasion of particles such as particle dust or
small particles fall directly in the loading hole. This can
be significantly reduced by installation of 90 circular
impingement plates of at minimum 20mm diameter above the
loading holes. These impingement plates could be installed
in the stiff distribution screen with openings of 16mm
3. The catalyst loaded with outage
The method given in example 1 and 2 can be best used
when no or a short outage is required. A short outage can be
created by vacuuming the particles from the top of the tube.
Use of vacuum to vacuum particles to an outage more than 0.2
m causes catalyst damage.
There are three different ways to achieve longer
outages efficiently with minimal damage to catalyst. The
different ways will be explained based on a modification of
example 2.
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Instead of the integrated loading and cover plate of
example 2, the filling assembly as shown in figure 2 is used
without a fixed coupling to the loading plates. At the
location of the loading holes there is a circular opening
with a diameter of 48 mm. In the cover sheet there are slots
of 2 mm. Three sub examples are given for outages of
a. 0.2 m
b. 0.7 m
c. 1.2m
a) Outage 0.2 m
In 90 vessel tubes loading plates with a loading hole
of 17 mm connected to a 0.27 m filling tube with inner
diameter of 20 mm, are installed corresponding with the
circular openings of the cover sheet. Similarly to example 2
the 90 vessel tubes are loaded with catalyst via the loading
plate. The cover plate is taken away and the catalyst in the
filling tube is shaken in the vessel tube leaving an outage
of 0.2 m. Particle dust and small particles are vacuumed
from between the vessel tubes.
b) Outage 0.7m with closing cone
In 90 vessel tubes loading plates with a loading hole
of 17 mm connected to a filling tube with inner diameter of
20 mm and closing cone (as depicted in figure 5) are
installed corresponding with the circular openings of the
cover sheet. Similarly to example 2 the 90 vessel tubes are
loaded with catalyst to at least 0.7m below the loading
plate. Subsequently the filling tube is closed by upward
movement of the cone, and the filling assembly is removed
(as depicted in figure 7).
In case the filling tube doesn't contain catalyst the
vessel tube is marked for a check and additional catalyst
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fill. This is repeated for all 90 vessel tubes covered by
the filling assembly.
This procedure is repeated until all 9000 vessel tubes
are loaded with 10 kg particles. At the outer edge of the
5 tube sheet different shapes of filling assemblies are
provided to fit the shape of the vessel tube assembly.
c) Outage 1.2 m with vacuum
Loading plates with a loading hole of 20mm connected to
10 a 1.2m filling tube with inner diameter of 22 mm are
installed in 90 vessel tubes corresponding with the circular
openings of the cover sheet of which an example is shown in
figure 2. Similarly to example 2, the 90 vessel tubes are
loaded with catalyst. It is not required to load catalyst to
15 the loading plate. Catalyst should be loaded at least to 1.2
m below the loading plate. Thereafter the cover plate is
removed.
The loading plate filling tube assembly is taken away
by a vacuum hose with conical tip that is put in the loading
20 hole and that is moved upwards (as depicted in figure 8). In
the vacuum hose a screen is built to prevent catalyst to go
into the hose. Alternatively a vacuum hose with screen is
put on the loading plate and moved upwards. The catalyst in
the filling tube is recycled. In case the filling tube
25 doesn't contain catalyst the vessel tube is marked for a
check and additional catalyst fill. This is repeated for all
90 vessel tubes covered by the filling assembly.
Particle dust and small particles are vacuumed from
between the vessel tubes.
4. Integrated loading and cover plate with closing device.
Tubes have to be loaded with an outage of 1.2m. In 90
reactor tubes a catalyst sensor is installed 1.2 m below the
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top of the tube. The sensor actuates a loading hole closing
device that is put on top of the tube. The sensor is a
specially designed electrical switch. That switch consists
of bent plates with a radius of the inner tube diameter with
a height of 0.05 m and a width that the plate covers 40% of
the circumference as shown in figure 11. Within the switch
two tips or connectors are installed connected to a low
voltage electrical source that act as an electrical switch.
When the tube is loaded with catalyst and the catalyst
reaches the plate, the plate is pushed to the inner tube
surface and the connectors close the electrical circuit. The
electrical circuit is connected to a solenoid that closes
the loading hole.
The 90 sensor closing devices are installed in the
pattern of the loading holes of the filling assembly as
described in example 2. The filling assembly as described in
example 2 is installed on top of the 90 reactor tubes with
sensor closing devices. Similarly to example 2 the 90 vessel
tubes are loaded with catalyst. As soon as the catalyst
reaches the catalyst sensor 1.2 m below the top of the tube
the loading hole is closed. After closure of all 90 loading
holes the filling assembly is removed and the 90 sensor
closing devices are taken out of the reactor tube.
Particle dust and small particles are vacuumed from
between the vessel tubes.
5. The catalyst loaded via holes punched in screens with
no or short tube outage
In a screen with wires of 0.9 mm with openings of 2 mm
in a rhombus shape with equal sides of 700 mm with 60 and
120 degrees angle, according to the triangle pitch of the
tube array, 121 holes of 19 mm are punched. The wires in the
hole are punched downwards. On the downwards punched wires
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44mm round plates with 20 mm loading holes are mounted and
fixed by the wires that were punched downwards. In total 40
of these rhombus shaped screens with 121 plates are made and
are put to cover half of the reactor tube sheet such that
half of the reactor tubes are covered with the loading
plates. At the circumference of the tube sheet the rhombus
shaped screens are adjusted to the shape of the tube sheet
circumference. With two men these screens are installed in
30 minutes. On the screen a grid of bars shaped as in figure
3 for the 121 loading holes in the shape of the screen is
put on the screen.
An amount of 1210 kg of catalyst is fed to two
vibrating screens outside the reactor after the first
screens with plates are installed on the tube sheet. The two
vibrating screens remove dust and transport 2 kg of catalyst
per second each to a hose with an outlet device that evenly
spreads the catalyst over the screen with 121 plates. As an
alternative the device to distribute the catalyst as
mentioned in example 2, but adjusted for 121 loading holes,
can be used. The catalyst is slid by the grid of barsover
these screens in to the vessel tube. Every six minutes the
121 tubes of one screen are loaded and the hose with outlet
device is moved to the next screen.
The screen with 121 plates and grid is moved to the
other half of the reactor and dust and small particles are
vacuumed from the tube sheet. After slightly more than 7
hours the whole reactor is loaded and 20 minutes later all
screens are taken away, the dust is vacuumed and the loaded
tubes are covered. In total the catalyst has been loaded in
slightly more than 8 hours.
In case a short outage is required the top catalyst can
be vacuumed from the tube.
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6. The catalyst loaded via holes burned in screens with no
or short tube outage
This is a modification of example 5. The 121 holes with
19 mm diameter are not punched but burned in the rhombus
shape screen. Burning causes that the individual wires of
the screen sinter or melt together at the edge of the
loading hole. No plates with loading holes are installed in
the screens and the screens are put directly on the vessel
tubes. This causes that during loading a very small amount
of catalyst dust and small particles fall into the tubes.
The features as described with the impingement plates in
example 2 adjusted for the 121 loading holes can be used to
prevent loading of catalyst dust and small particles.
7. The catalyst loaded via holes burned in a screen with
0.7m tube outage
Ninety loading plates are connected to each other via
bars (as depicted in figure 9). The loading plates have a
loading hole with diameter of 20 mm and are connected to
20mm filling tubes of 0.7m. The 90 loading plates with
filling tube are installed in 90 vessel tubes. In a rhombus
shaped screen with wires of 0.9mm and 2 mm openings between
the wires, 90 holes of 19mm diameter are burned at
locations corresponding with the openings of the loading
holes. The screen is put in a stiff frame with partitions
around the rhombus. On the screen with partitions a grid as
shown in figure 3 is mounted and the assembly is put on the
90 loading plates (analogously to figure 4). The catalyst is
loaded into the tubes as mentioned in example 2. After the
catalyst has been loaded in all 90 tubes to at least 0.7 m
from the top the screen and grid is taken away.
A vacuum hose with inner diameter of 22 mm is put on
the loading plate. The catalyst is vacuumed from the filling
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tubes. When all 90 tubes are empty the assembly of ninety
loading plates are taken out of the tubes.
8. The catalyst loaded via holes burned in a screen with
1.2 m tube outage
Ninety loading plates with a diameter of 20 mm are
connected to 20mm filling tubes of 1.2m long. The filling
tube is provided with side ventilation ports as shown in
figure 10. The ports are 4mm wide 50mm long openings, with
three openings next to each other at the same level,
repeating at several levels. In the middle opening a valve
is mounted at each level. Ninety of these loading plates and
filling tubes are installed in 90 tubes similar to example 7
as well as the catalyst is loaded as described in example 7.
After the catalyst has been loaded in all 90 tubes to at
least 1.2 m from the top the screen and frame is taken away.
At the levels where the filling tube contains catalyst,
the valve is forced in an open position by the particles.
When the vacuum hose is put on the loading plate, air is
sucked into the filling tube via the side openings and the
bottom opening. This improves fluidisation and easy removal
of the particles from the filling tube. When a level in the
filling tube is free of particles, the valve closes by the
vacuum at that level.
At the bottom of the filling tube also a valve could be
mounted that closes when the catalyst is vacuumed from the
filling tube in order to prevent loss of vacuum.
In this way more than one filling tube can be vacuumed
at the same time. When the bottom valve would not close the
vacuum to the other filling tubes would drop as soon as one
tube was emptied. When all 90 tubes are empty the ninety
loading plates and filling tubes are taken out of the tube.
