Loading Device for Loading Particles, Method for Loading Particles Using a Loading Device

Abstract

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 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.

Description

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.

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 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 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 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 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 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 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 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 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 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 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 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 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.

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 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.

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.

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.

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.

FIG. 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 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 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.

FIG. 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. FIG. 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 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 FIG. 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.

FIG. 3 shows an example of a grid 30 which follows the same pattern as the cover plate 20 of FIG. 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 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.

FIG. 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 FIG. 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 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.

FIG. 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 FIG. 6, particles 80 are loaded in the vessel tube 74, while some particles remain in conduit 72.

FIG. 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.

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.

FIG. 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 FIG. 8, the vacuum is used to retain (secure) the particles in the filling tube 72. For that reason, a sieve 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.

FIG. 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 FIG. 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.

FIG. 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 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 FIG. 10a). The closing lids 162 are normally in closed position over the side ventilation ports 160 when the particles are absent and the conduit is put under vacuum (FIG. 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.

FIG. 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 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, 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 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. FIG. 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 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 FIG. 3 is put on the integrated loading and cover plate. On the four sides of the grid 40 mm high partitions are mounted.

Catalyst from a big bag containing 900 kg of catalyst is fed to a vibrating screen outside the reactor. The screen removes dust and transports 90 kg of catalyst per minute to a hose with an outlet device that evenly spreads the catalyst on a stiff distribution screen with openings of 16 mm. The distribution screen has the rhombus shape of FIGS. 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 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 10 kg 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 20 mm diameter above the loading holes. These impingement plates could be installed in the stiff distribution screen with openings of 16 mm

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.

Instead of the integrated loading and cover plate of example 2, the filling assembly as shown in FIG. 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. 1.2 m

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 0.7 m 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 FIG. 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 0.7 m 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 FIG. 7).

In case the filling tube 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.

This procedure is repeated until all 9000 vessel tubes are loaded with 10 kg particles. At the outer edge of the 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 20 mm connected to a 1.2 m 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 FIG. 2. Similarly to example 2, the 90 vessel tubes are loaded with catalyst. It is not required to load catalyst to 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 hole and that is moved upwards (as depicted in FIG. 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 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 1.2 m. In 90 reactor tubes a catalyst sensor is installed 1.2 m below the 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 FIG. 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 44 mm 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 FIG. 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.

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 0.7 m Tube Outage

Ninety loading plates are connected to each other via bars (as depicted in FIG. 9). The loading plates have a loading hole with diameter of 20 mm and are connected to 20 mm filling tubes of 0.7 m. The 90 loading plates with filling tube are installed in 90 vessel tubes. In a rhombus shaped screen with wires of 0.9 mm and 2 mm openings between the wires, 90 holes of 19 mm 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 FIG. 3 is mounted and the assembly is put on the 90 loading plates (analogously to FIG. 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 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 20 mm filling tubes of 1.2 m long. The filling tube is provided with side ventilation ports as shown in FIG. 10. The ports are 4 mm wide 50 mm 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.

Claims

1. 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 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.

2. Loading device according to claim 1, wherein the sieving openings are smaller than the particles to be loaded.

3. Loading device according to claim 1, wherein the sieving means are made of wires, rods, gauze or screens.

4. Loading device according to claim 1, wherein 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.

5. Loading device according to claim 1, wherein the device further comprises a grid of 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.

6. Loading device according to claim 5, wherein a friction reducing material is provided at the side of the grid that is directed towards the plate and its sieving means.

7. Loading device according to claim 1, wherein above said device a distribution plate is provided which has openings larger than the particles to be loaded.

8. Loading device according to claim 1, wherein a conduit is 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.

9. Loading device according to claim 8, which includes a vacuum hose connectable to the loading hole.

10. Loading device according to claim 9, wherein a sieve is provided at the end of the hose which is connectable to the conduit, the sieve having openings smaller than the particles present in the conduit.

11. Loading device according to claim 8, wherein the conduit is provided with side ventilation ports, the ports having a smaller size than the particles to be loaded.

12. Loading device according to claim 11, wherein the ports are closable by a vacuum applied to the inside of the conduit.

13. Loading device according to claim 1, wherein the loading holes 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.

14. 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 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.

15. Loading device according to claim 14, wherein a sieve is provided at the end of the hose which is connectable to the conduit, the sieve having openings smaller than the particles present in the conduit.

16. Loading device according to claim 14, wherein the conduit is provided with side ventilation ports, the ports having a smaller size than the particles to be loaded.

17. Loading device according to claim 16, wherein the ports are closable by a vacuum applied to the inside of the conduit.

18. 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.

19. 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, 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.

20. Assembly of an array of tubes and a loading device for loading particles through the entries of 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 the tube comprises a sensor for detecting the loading volume in the tube, and a closing means for closing the path of particles that enter the tube, wherein the sensor controls the closing means.

21. Assembly according to claim 20, wherein said sensor controls the closing means when a predetermined volume of particles is loaded.

22. Assembly according to claim 20, in which the sensor is an electrical switch activated by the loaded particles.

23. Loading device according to claim 13, wherein said closing means is a movable stop which is conically shaped.

24. Loading device according to claim 8, wherein the conduit consists of telescopic tube parts.

25. Loading device according to claim 8, wherein the conduit comprises a closing means for closing the exit of the conduit, wherein the closing means is a movable stop which is conically shaped, and which is connected to a rod for moving the stop up and down along the axis of the conduit between a closed and an opened position.

26. Loading device according to claim 20, wherein said closing means is a movable stop which is conically shaped.