Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Method of filling apparatuses with solids
The invention relates to a method for filling apparatuses
used in chemical production with solids using a regulatable
metering device, and an apparatus, displaceable from place
to place, for carrying out the method. The apparatus is
particularly suitable for filling heat exchangers,
absorption columns, distillation columns or tube-bundle
reactors with solids.
The uniform filling of solids into tubes, tube-bundles or
heat exchangers is of decisive importance for the
efficiency of these apparatuses. The solids may be, for
example, packings, such as Raschig rings, ceramic balls or
catalysts and may have different compositions and
geometries, such as, for example, those of spheres, solid
cylinders, hollow cylinders or rings.
The prior art discloses methods and apparatuses for filling
tube reactors with shaped catalysts.
US 4,402,643 and EP 0 904 831 B(US 6,170,670 Bl) describe
the feeding of particulate material and the associated
apparatuses, the material being transported via a channel
caused to vibrate into the tubes to be filled.
According to EP 0 904 831, fine dust falls through the
sieve-like bottom of the channel into a separate container.
If, for example, catalyst mouldings are destroyed or
damaged during filling, the resulting catalyst bed is no
longer homogeneous. Fine abraded material (dust) and
catalyst fragments lead to the formation of cavities and
channels so that nonuniform flow through the tube leads to
reduced or increased pressure drops. This impairs the
efficiency or throughput of the apparatus.
According to the prior art, dust is separated off by
sieving but dust pollution is not avoided thereby. Dust
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adhering to the catalyst particles is also not separated
off by this method.
This problem is solved according to the invention.
The invention relates to a method for filling tubes with
solids, in which the solid is discharged from a filling
funnel (2) onto a skew plane having vibrating channels (4),
which is arranged in an approximately horizontal position
and extends from the discharge orifice of the funnel up to
at least the connection to the drop tube (5) or a flexibile
hose connection, through which the solid is fed to the tube
to be filled, characterized in that in each case
a) the outlet tube (6) mounted on the drop tube (5) is
adjusted in its height in a suitable manner,
b) dust is extracted by an extraction tube (10) and an
extraction apparatus (1), which are present in the
vicinity of the filling funnel (2) and the outlet tube
(6), and application of reduced pressure, and
c) after the filling of the tubes, the apparatus mounted
on rollers or rolls (11) is moved for filling further
tubes.
The solid is thus metered in a uniform manner by control or
regulation of the vibration frequency of the vibrating
channel (4).
The amount metered or the metering rate can also be
adjusted, optionally simultaneously, by means of the flow
controller (3) which is adjustable in height and has the
form of a weir.
The drop tubes which are adjustable in their height or the
flexibile hose connections prove to be particularly
advantageous because in this way small differences in the
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height of the tubes to be filled can also be compensated
and gaps between drop tube and reactor tube are avoided.
The solids to be filled, which preferably have a mean
particle size of at least 1 mm, may be mouldings of
different type and suitability, such as, for example,
Raschig rings, ceramic balls, inert bodies or shaped
catalysts, for example in the form of granules, extrudates
or pelletts in the commercial dimensions.
Reactions with such catalysts are, for example, the
preparation of ethylene oxide, phthalic anhydride,
acrolein, acrylic acid, methyl mercaptan, hydrogen sulphide
and others.
The object of the invention is to obtain a homogeneous
solid bed and to avoid mechanical destruction of the
solids. Zone-by-zone filling of the solids can
advantageously be achieved by the method described here, so
that different fillings of solids having exactly defined
volume can simultaneously be introduced along the axial
profile of the tube. When applied to a multiplicity of
tubes (e.g. n = 2-100 000), the method according to the
invention is characterized by a uniform distribution of the
heights of fill, so that, when the tubes are fed with a
constant gas flow, differential dynamic pressures with a
mean standard deviation from the mean value of in general
less than 10% result.
At the same time, dust pollution should be avoided during
the filling process.
According to the invention, the filling of the solid is
effected by means of an apparatus as shown in figures 1 and
5. With the apparatus according to the invention, x tubes
(x = 1-50) can be simultaneously filled. Figure 1 shows,
for example, an apparatus with which x = 5 tubes can be
simultaneously filled. For this purpose, the amount of
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solid to be filled for each reaction tube is first
determined volumetrically or gravimetrically and initially
introduced into a collecting vessel. The amount to be
filled is preferably determined gravimetrically. The
collecting vessel has at least the volume of the solids to
be filled. The collecting vessel is opened and is
introduced with the opening facing downwards into a filling
funnel 2. The solids are loosened by means of an apparatus
initially by vibrations, are caused to execute oscillatory
and translational movement and are fed via a skew plane 4
(vibrating channel) uniformly to a metering device. The
number of channels on the skew plane corresponds to the
number of tubes to be filled simultaneously each time.
The metering device is connected to the apparatus to be
filled (for example a reaction tube in tube-bundle
reactors) by means of drop tubes 5 adjustable in height,
and permits loss-free feeding of the solids by means of an
outflow tube 6 adjustable in height. Apparatuses which
permit a direct connection between the apparatus for
filling solid beds and the apparatus to be filled are used
as the metering device. Funnels, tubes and flexible hose
connections are expedient for this purpose. These metering
devices are preferably designed as drop tubes (5 and 6)
adjustable in length or flexible hose connections, so that
a continuous connection exists between the apparatus to be
filled (for example a tube-bundle reactor) and the
portioning device. As a result, the solids can be metered
without scattering losses or the like into the apparatuses
to be filled. Furthermore, the dust emission during the
filling process is minimized. Figure 1 shows that one
connection each for an extraction apparatus 1 and an
extraction tube 10, by means of which the dust optionally
occurring as a result of application of reduced pressure
and solid particles are extracted, is present in the
vicinity of the filling funnel and the drop tubes
adjustable in height.
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For the filling process, it is decisive that the solid bed
be fed in a uniform, slow and reproducible mass flow to the
apparatus. This apparatus may be a heat exchanger, an
absorption column, a distillation column and a tube-bundle
5 reactor. Tube-bundle heat exchangers which are used as
reactors are particularly preferred. These reaction tubes
may also have internals (e.g. thermocouples). The
apparatus according to the invention permits control of the
mass flow by variation of the vibration frequency of the
apparatus, advantageously by means of electrical thyristor
control 7. Regulation of the mass flow is also possible by
means of the flow controller 3 at the transition from the
filling funnel to the vibrating channels, which flow
regulator is adjustable in height. The solid bed should be
fed to the apparatus by a uniform vibratory movement of the
collecting container, of the skew plane and of the metering
device. Advantageously, a collecting apparatus (filling
funnel) for the solid filling, a feed device (skew plane)
and a metering device are integrated in one apparatus. Up
to 50, preferably up to 20, of these apparatuses can be
integrated in a portioning device in order to fill a
plurality of tubes or the like simultaneously and
efficiently. Figure 1 shows, for example, an apparatus by
means of which 5 tubes can be filled simultaneously. By
the simultaneous filling of a plurality of tubes,
reproducible, uniform filling is ensured. For metering, up
to 50 metering units (x = 1-50), are expediently used in a
portioning device, and from 1 to 10 metering units (x = 1 -
10) are particularly suitable in a portioning device.
Ideally, the solids are set into motion by vibration of a
skew plane. Of particular importance here is the exact and
fine adjustment of the vibration in order to keep the flow
rate as uniform as possible. This requirement is met by
commercial electrical vibrator motors. Variation of the
vibration frequency by means of an electronic control
enables the intensity of vibration of the solid and hence
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the outflow rate thereof to be influenced. Figures 1 and 4
show, for example, a skew track having an arrangement of n
= 5 channels, which can be caused to perform vibratory
movements simultaneously. This plane is advantageously
closed by a preferably transparent cover (e.g. of plastic)
in order to avoid a loss of solids and dust emissions.
A tube orifice 10 which, when connected to an extraction
device, ensures removal of solid dust and impurities is
advantageously present in the vicinity of the orifices of
the metering device.
Ideally, the apparatus is mounted on rollers or rolls 11 so
that it can be operated and moved simultaneously by one
person. For simple handling of the apparatus, the roll can
be adjusted in height.
With the aid of the method described, it is possible to
keep the variation of the metering of the solids in general
less than +/-5%.
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Examples
Example 1:
Design of the filling machines (Figures 1-6):
a) The filling machine has the following design:
= Extraction in the upper part (1) of the filling
machine and in the outlet tubes (10).
= Five filling funnels (2).
= Slide (3) with wing nuts at the outlet to the
vibrating channel (4) for adjusting the delivery
(flow controller adjustable in height).
= Vibrating channel (4) via which the catalyst is
transported into the drop tubes (5).
= Potentiometer (7) for adjusting the intensity of
the vibration of the vibrating plate.
= An adjustable transport roll (11).
= Two handles (8, 9).
= Extensions of the outlet tubes (6) with wing nuts
and tapered exit which fits into the tubes of the
reactor.
b) Adjustment and optimization of the filling time on the
filling machines:
= The filling machine is mounted above the tubes to
be filled.
= In general, the filling time can be adjusted by
means of two parameters:
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= by means of the slide, acting as a flow controller
adjustable in height and adjustable by means of
wing nuts 3, at the outlet to the vibrating plate
= by means of a potentiometer 7 which controls the
vibration of the outlet channels.
It is expedient to adjust the orifice of the outlet
roughly by means of the wing nut 3 and to make the
fine adjustment by means of the potentiometer 7. The
first fills are used for further optimization of the
machine. The height of fill serves for checking the
correct filling of the tubes. The machine is too fast
if the tube is filled too high, or the machine is
transporting the catalyst too slowly into the tube if
the tube is filled too low. In both cases, the
filling rate is regulated by means of the two
abovementioned parameters so that the tubes are filled
as homogeneously as possible.
c) Filling of the catalyst:
The solids are preferably filled zone-by-zone so that
different fillings of solids are introduced
simultaneously along the axial profile of the reaction
tube with exactly definable heights of fill, fill
volumes and masses.
Reaction tubes which contain internals for controlling
the reactor are preferably filled in such a way that
at least one catalyst particle per second is metered
into the tube, and the formation of dead zones and
channels, which result in an increased differential
pressure drop, are thus avoided.
The transport roll 11 of the filling machine is
adjusted so that, after each fill of a series, the
machine can conveniently be pushed forwards.
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The catalyst to be filled is packed in collecting
vessels, e.g. cans (1 can/tube).
The invention also relates to an apparatus, displaceable
from place to place, for filling tubes with solids,
comprising
a) a filling funnel (2) for storing the solid,
b) a skew plane having channels (4) which are arranged
thereon and which are arranged in an approximately
horizontal position and extend from the discharge
orifice of the funnel up to at least the connection to
the drop tube (5) through which the solid is fed to
the tubes to be filled, characterized in that in each
case
c) the outlet tube (6) connected to the drop tube (5) can
be adjusted in its height,
d) reduced pressure can be applied and dust extracted by
means of an extraction tube (10) and an extraction
apparatus (1) in the vicinity of the filling funnel
(2) and the outlet tube (6), and
e) the apparatus is mounted on rollers or rolls (11).
The cross section of the drop tube is at most equal to the
cross section of the tube to be filled. Preferably, it has
a smaller cross section and tapers conically at its ends so
that it fits into the tube to be filled.
Brief description of the figures
Figure 1 shows an arrangement according to the invention
(side view) of a portioning device for the simultaneous
filling of five tubes with particulate solids.
Figure 2 shows an arrangement according to the invention of
the filling funnel and of the connection for an extraction
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apparatus of a portioning device for the simultaneous
filling of five tubes with particulate solids (view from
above).
Figure 3 shows an arrangement according to the invention of
5 the drop tubes and of the height-adjustable outflow of a
portioning device for the simultaneous filling of five
tubes with particulate solids (view from the front).
Figure 4 shows an arrangement according to the invention of
the vibrating channels of a portioning device for the
10 simultaneous filling of five tubes with particulate solids
(view from above).
Figure 5 shows an arrangement according to the invention
(side view) of a portioning device for the filling of a
tube with particulate solids.
Figures 6 shows an arrangement according to the invention
(view from above) of a portioning device for the filling of
a tube with particulate solids.
The numerals in the figures denote:
1) Connection for extraction apparatus
2) Filling funnel
3) Flow controller adjustable in height
4) Skew plane with vibrating channel(s)
5) Drop tube
6) Outflow adjustable in height(wing nut)
7) Switchbox
8) Carrying handles
9) Pushing handle
10) Extraction tube
11) Transport roll adjustable in height
