NL2003298A

NL2003298A - Loading of vertical assemblies of tubes with solid particles.

Info

Publication number: NL2003298A
Application number: NL2003298A
Authority: NL
Inventors: Arend Jan Te Raa
Original assignee: Arend Jan Te Raa
Priority date: 2008-12-10
Filing date: 2009-07-28
Publication date: 2010-06-11
Also published as: CA2743284A1; WO2010068094A2; WO2010068094A3; NL2003298C2; US20110277421A1; BRPI0923371A2; CA2743284C; CN102245287A; EP2364204A2

Description

LOADING OF VERTICAL ASSEMBLIES OF TUBES WITH SOLID PARTICLES Background of the invention

Assemblies of tubes found in industry often have to be loaded with equal amounts of particles with respect to volume, loading height, mass and porosity. These assemblies of tubes are normally mounted in vessels. The assemblies of tubes are often found in refineries and chemical industry, in particular in heat exchangers or reactors that require heating or cooling of a fluid flowing through the tube assembly. Identical loading is required because the flow of the fluid through each tube as well as the residence time in each tube of the assembly should be equal.

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 particles are supplied in 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.

The main problem of loading of solid particles in tubes is bridging of particles at the top or inside the tube. Bridging occurs when several particles come together and the sum of their lengths is more than the tube diameter. The particles are then fixed in place at the opening of the tube or part way down the tube above the particle bed and leave a void space below them, resulting in unevenly and incompletely loaded tubes. Solutions to this so-called bridging problem have been proposed and successfully applied.

In patent publication, many inventions have been disclosed to achieve this even distribution of particles over the tube assembly.

The solutions use different kinds of devices to load particles in such way that the sum of the lengths of the particles that come together (form bridges) before reaching the particle bed is less than the tube diameter. These devices load the particles in a controlled manner such that the sum of the lengths of the particles loaded within a short time is less than the tube diameter.

The devices can be separated in two main groups identified as machine loading or orifice loading.

With machine loading, the container of particles is emptied in the machine and the machine transports the particles at a controlled speed to the tubes by use of belts or vibrators. The particles are transported at that speed that the sum of the lengths of the particles that come together before the particles reach the particle bed is never more than the tube diameter. Orifice loading uses an orifice as loading hole through which the particles are fed to the tube being loaded. The word "orifice” is used in the meaning of a controlled opening less than the opening of the tube. The oldest orifice used is the lowest part of a funnel put into the top of the tube that has to be loaded. The particles are moved manually from a tube pack into the wide top part of the funnel with an outlet bottom part smaller in diameter than the tube diameter. Another old technique is using a plate with holes which locations on the plate match those of the tube openings in the tube assembly. The diameters of the holes are smaller than those of the tubes. The catalyst is dumped from the container onto the plate and swept or vibrated into the tubes through the loading holes. In this document this hole is called loading hole in order to discriminate it from holes with other purpose.

A more recent technique is to put a small plate with one orifice on each tube. The plates can be constructed in a way that the assembly of plates make a closed surface on which catalyst can be dumped before it is swept into the tubes.

With orifice loading as described above the particles are loaded to the top of the tube. Often, however, a specified length at the top of the tube needs to remain clear of particles, in other words needs to stay unloaded. That part is often called outage. With machine loading, the amount of catalyst loaded into a tube of the tube assembly is controlled by the machine in such way that the outage is free of particles.

As mentioned with the technique that uses orifices, the loading of particles is stopped when the loaded particles in the tube reach the plate and stop falling into the tube. For orifice loading, the following first two techniques are widely applied to create an outage: 1. Vacuuming particles from the top to the required outage, 2. Use of a filling tube in the tube that has to be loaded.

3. Use of a sleeve and securing pellets in the sleeve and use of the tendency to bridge inside sleeve

The first technique 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 uses a filling tube. To discriminate between different types of tubes, the tubes of the tube assembly that have to be loaded with particles will be called vessel tubes and the tubes used to load the vessel tubes are called filling tubes. In case the vessel is a reactor the vessel tubes can also be called reactor tubes.

For the second technique, the loading hole is connected to a filling tube that 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. These filling tubes guide the particles into the vessel tubes. As mentioned earlier, without a filling tube the particles will be loaded up to the plate level. With a filling tube an outage is created with an outage length after removing the filling tube that depends on the particle volume in the filling tube and the bridging properties of the particles in the filling tube. These bridging properties determine how much particles fall from the filling tube in the vessel tube,

The third mentioned technique was recently described in a patent. After loading the sleeve is removed from the vessel tube with the particles in the sleeve.

Additionally to above mentioned requirement of even loading, the invention of this patent relates to efficient loading meaning using minimal resources in the shortest time. Additionally, the invention aims at a significant reduction of abrasion (attrition, erosion) of the particles and reduction of loading of the inevitable product of abrasion such as broken particles or particle dust in the vessel tubes.

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 particles of smaller size than allowed in the vessel tube and dust. This is very undesirable because the small particles or dust change the fluid transport properties of the medium flowing through the reactor tubes and cause problems outside the vessel tubes. 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. Abrasion and dust formation has to be prevented or minimized and the inevitable products of abrasion and dust formation have to be removed from the particles. Previously patented technology A wealth of technology has been developed to achieve even loading of which many technologies have been reported in patents.

U.S. Pat. No. 3,223,490, issued 14 Dec. 1965, discloses a reactor tube loader which comprises a perforated plate which rests on the reactor tubes, the perforations corresponding to the pattern and spacing of the reactor tubes and are connected to fill tubes, one for each reactor tube, which nest in the perforated plate and extends into the corresponding reactor tubes, In operation, catalyst is dumped onto the perforated plate and the plate is shaken by a vibrating mechanism, causing the catalyst particles to pass through the fill tubes into the reactor tubes one by one. The same publication adds that the fill tubes may be made of such length that when they are loaded to their top with catalyst and then removed from the vessel tubes, their contents fill the vessel tubes up to a predetermined point below the top thereof.

DE 3601366 published 29-07-1987, also discloses a reactor tube filling device consisting of a plate resting on the reactor tubes and fill tubes nesting in the plate and extending into the corresponding reactor tubes. The differences with the first document are that the fill tubes are firmly connected to the plate and that a vibrating mechanism is not mentioned. The function of the device according to this document is to ensure that all reactor tubes are filled to a fixed level below their top by dumping the contents of the fill tube in the reactor tube. The phenomenon of bridging is not mentioned.

Because the above mentioned catalyst loading devices are inflexible, big, heavy and cumbersome to introduce into the upper reactor part, a loading device of one polygonal plate per reactor tube was described in patent EP0963785 published 1999-12-15 and extended in US 2005/0220685. The detailed description of the invention mentions dust removal. In profile, the polygonal plate may be undercut in its downward surface, so as to allow even more space for accommodating the dust. Alternatively the insert extending from the polygonal plate into the reactor tube can be made to carry a shoulder which will also allow space between the polygonal plate and the upper tube sheet for accommodating dust. The length of the shoulder can suitably be about 1 cm. For the same purpose of accommodating dust, the polygonal plate can be perforated with slits or small holes. The polygonal plate may also taper in its upward surface towards the hole or holes, in order to facilitate the particles' falling into the reactor tube.

In claim 10 (US 2005/0220685) dust removal is described via a spacing between adjacent plates the spacing having a width less than the smallest dimension of a single whole particle To achieve the loading height the patent describes that after removal of the loading device, the catalyst level in each reactor tube dropped below the level of the tubesheet. Vacuum was then used to further evacuate catalyst particles from the top of each reactor pipe to a level below the tube sheet.

Patent US 2004/0261898 published Dec. 30 2004 deviates from the polygonal plate and describes a circular plate with noses. This invention is expanded in patent US 2006/0054242 published March 16, 2006 in which the plate was replaced by a funnel element and a pouring device was located above the assembly of funnel elements.

Similar to above mentioned last three patents in patent W02004/085051, published 7 October 2004, a tool is described to load catalyst and measure outage. The outage is measured by markings on the loading (filling) tube (sleeve). Different from above mentioned patents the plate or funnel is round and looks like a flange. These flanges can overlap each other and cover the surface between the vessel tubes. When the flanges overlap dust may be swept or vacuumed off. The patent is significantly expanded in patent US 2007/0098605.

It aims at solving the bridging of particles in the filling tube, reducing abrasion by absorbing kinetic energy of the particles. In the description it is mentioned that there is a substantial distance between the flanges, large enough to allow whole pellets to fall between the flanges onto the tube sheet. This provides a substantial space for and broken pellets to accumulate on the tube sheet, where they can be collected, and helps prevent the dust and broken pellets from entering the reactor tubes. Further on it states a flange with dust-receiving recesses of various shapes, for receiving dust. The dust-receiving recesses extend downwardly from the top surface of the flange, but they do not extend completely through the flange. They collect dust and fine particles as the whole pellets are being swept up, dropped, or otherwise moved toward the opening. The dimensions of the recesses are small enough to prevent the whole pellets from falling in. This description returns in their final claim.

The description also mentions a loading device with dust holes and dust slots that extend completely through the flange. In this case, the holes and slots are limited to the area of the flange between the outer tubular sleeve portion and the outer edge of the flange so the dust that falls through the holes and slots will land on the tube sheet and will not fall into the reactor tube. Again, the dimensions of the holes and slots and are small enough to prevent whole pellets from falling through the holes and slots. The holes and/or slots could extend around the entire circumference of the flange, or there could be areas where there are no holes or slots.

The patent writes that in typical loading procedures, the reactor tubes are filled to the top with catalyst, and then the catalyst is vacuumed out to the desired "outage" level, with the "outage" being the empty space within the reactor tube above the catalyst. This process is labor intensive and tends to degrade the catalyst, so it would be desirable to be able to load the catalyst pellets directly to a required "outage" level, such that pellets do not have to be vacuumed out or added after the loading in order to reach the desired outage level. The patent introduces "gripping sleeves", loading devices that permit the pellets to fall through during the loading process and then retain the pellets that are remaining in the loading device as it is being lifted out. Many examples are given such as by use of a sleeve and securing pellets in the sleeve by use of the tendency to bridge inside sleeve by reducing the internal cross sectional area near its outlet opening, the use of clip obstructions or pins, the use of inflating bladders or lasso’s.

Patent US2008/0142045 claims a method of vacuuming solid particles out of a vertical chemical reactor tube to a desired outage, by putting a vacuum conduit into the top of the tube; vacuuming solid particles and gas out of the reactor tube through the vacuum conduit to a collection hopper; and substantially reducing the vacuum when the vacuum conduit inlet reaches a desired depth within the reactor tube. Also introduction of an external gas into the reactor tube through a second flow path extending through the top of the reactor tube is claimed

None of the inventions mentioned above achieve the overall requirement of even loading, even outage, dust formation prevention, removal of the inevitable product of abrasion and dust and efficient use of time and capital. The above mentioned inventions achieve only parts of the requirements of efficient, even, and dust-free particle loading in tube assemblies.

Brief description of the Invention.

The invention is an improvement of the well known technology to load particles in tubes via a loading plate that covers one or more tubes with respectively one or more loading holes corresponding with and smaller than the opening of the tubes that have to be loaded with particles. In the public domain this method of loading is also called orifice or template loading.

The invention deals with: 1. Even distribution of the particles over the tubes that have to be loaded and prevention of inevitable products of abrasion of the particles such as particle dust or small particles to fall in the tube 2. Removing the inevitable products of abrasion of the particles such as particle dust or small particles that are not allowed in the tubes just before the particles enter the tubes.

3. Sliding the particles with minimum movement into the tube 4. Efficiently loading to an outage

The particle that have to be loaded are evenly dropped via a hose on a distribution screen with a flat layer of particles. The openings in the screen are more than the particle size. The screen is shaken to cause a flat particle bed on the screen and particle rain through the screen openings. In the distribution screen impingement plates are mounted corresponding with the tube openings to prevent the inevitable products of abrasion of the particles such as particle dust or small particles to fall in the tube.

The inevitable products of abrasion of particles such as particle dust or small particles that are not allowed in the vessel tubes are removed via openings between bars or wires or openings of a screen installed in the area between the tubes and plates or via slots made in plates at the area between the corresponding tube openings. Particles are slid by a small movement of a frame into the vessel tube via the loading hole.

A sensor indicates when the outage that should stay free of particles is reached. The loading hole is closed when the outage is reached . Alternatively a filling tube is installed in the top of the vessel tube. Before removing this filling tube the bottom end of the tube is closed. Or alternatively a vacuum is put on top of this filling tube before and during removal of the filling tube.

Description of the invention

The present invention provides a device or an assembly of devices to efficiently load particles from containers evenly into an assembly of tubes while minimising abrasion of the particles, prevention that the inevitable products of abrasion fall into the tubes and removing these. In the following paragraphs, the invention will be described in sequence from installing the loading device, the unloading of the container of particles, to loading the tube and removing the tube loading device.

The loading device consists of a loading plate with one or more loading holes. The minimum length dimension of the plate is more than the maximum vessel tube opening dimension (inner vessel tube diameter). The loading plate is loosely located on the vessel tube in such a way that there is no opening to the vessel tube except for the loading hole. The minimum length dimension of the opening of the loading hole (hole diameter) is more than the maximum length dimension of the particles and smaller than the minimum cross sectional length dimension (inner diameter) of the vessel tube. As mentioned earlier, this hole is called loading hole in this document in order to discriminate this hole from other holes. An example of such loading plate with loading hole of 17 mm is given in figure 1 for a vessel tube with 39 mm inner diameter and 44 mm outer diameter. The loading plate as shown in figure 1 is the most elementary form of loading plates widely used in recent decades. Most common is a loading plate that covers up to hundreds of tubes with as many loading holes.

The loading plate with the loading hole can be mounted on a short support tube with an inner diameter more than the outer diameter of the vessel tube. The length of the short support tube should be equal to or more than the maximum length of the vessel tube above the tube sheet, for example 30 mm. This is useful in case of uneven height of the tubes of the tube assembly above the tube sheet. Such support tube can also be used to support the coversheet mentioned later in this paragraph.

Below each loading hole a loading hole closing device can be mounted that closes the loading hole when the particles reach the outage. Outage is the length in the top of the vessel tube that should be free of particles.

Alternatively each loading plate can be connected to a filling tube at the loading hole in case the vessel tube has to be filled with a top outage without particles. The minimum inner diameter of such filling tube has to be more than the diameter of the loading hole and the maximum outer diameter of the filling tube has to be less than the inner diameter of the vessel tube. The length of the filling tube is at least equal to the length of the required outage. In case a short outage is required the length of the filling tube can be longer than the outage. In that case the particles in the filling tube are put in the vessel tube to meet the outage requirement. In case a variable outage is required the filling tube is constructed from two or more tubes that are connected telescopic.

Between the loading plates 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.

The wires, rods or screens can also be connected to each other or to the loading plate. In that case the loading plates are assembled with wires or rods, or screens in such a way that when the assembly of plates is put on the assembly of vessel tubes, the centres of the loading holes in the plates align with the top vessel tube openings. In case a screen is used the loading plate can be mounted in the screen.

Instead of wires, rods or screens a plate can be used that covers the surface between one or more loading plates. This plate is called a cover plate in this document. Figure 2 demonstrates a cover plate for the openings between 90 loading plates of figure 1. (For clarity: the large holes in the cover plate are not the loading holes.) The circular holes in the cover have a diameter of 48 mm leaving 2 mm between the loading plates and the cover plate for removing particle dust. Further slots are made in the cover plate to remove particle dust. This cover plate could also be made of a screen with holes of 48 mm. The holes are larger than the outer diameter of the vessel tube. As an alternative the loading plates and cover plate can be connected to each other as shown in figure 3. The connection can be removable, clipped or fixed.

In case the plates are assembled with wires, rods, a screen or a cover plate the number of loading plates that is assembled is determined by efficiency of particle loading. The minimum number is one for example in case outer tubes of the tube assembly have to be loaded. The maximum is determined by handling limitations such as the size of the opening in the vessel (such as manhole) through which the device has to be transported or the weight of the loading assembly filled with particles.

When unloading the 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 a section with loading and cover plates to create a layer with a thickness of at maximum a few particles. In the screen impingement plates are 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 opening in the screen are more 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

In order to move the particles to the loading hole and break the particle bridges above the loading hole a grid of stiff straight wires or small bars has been put on the loading plates, wires, rods, screen or cover plate. The wires or bars of the grid have the same pitch as the vessel tubes. The grid is moved such that the wires or bars of the grid are moved to the loading hole. The particles are slid into the loading holes. Particle bridges above the loading holes that prevent the particles to drop in the hole are broken. An example of such frame for 90 vessel tubes is shown in figure 5. After the particles have been loaded the grid is taken away. Below the stiff grid soft and flexible material can be mounted to ease sliding and adjust to the particle shape.

In the case that the particles have been loaded with short filling tube this assembly is removed and the particles in the filling tube are shaken in the reactor tube to the appropriate particle height in the tube. This is feasible to an outage of at maximum 0.5m.

Alternatively a vacuum hose is attached to the plate and filling tube. The vacuum hose can have a conical end that is put into the loading hole of the loading plate. In the vacuum hose a screen can be installed to prevent particles to enter the screen. The filling tube, plate and vacuum hose is moved upwards. Because of the vacuum the particles are secured in the filling tube and are moved away from the loaded tubes. The particles in the filling tube are removed by breaking the vacuum and shaking at an appropriate location for these particles.

A screen can be mounted in the vacuum hose to prevent catalyst from transporting into the vacuum system. With this technology it is not required to load the particles to the plate. Alternatively at the lower end of the filling tube a movable blocking device can be mounted. When the device is mounted below the filling tube, the minimal distance to the filling tube should be more than the maximum length dimension of the particle that has to be loaded. Before removing the plate and filling tube, a force is exercised on the blocking device directed to the filling tube.

Most effective and efficient is to mount 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 or inner tube is required.

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 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.

All features of the invention are shown at different levels drawn as a cross section in figure 4. The particle supply hose and distributor is indicated as “a”. The distribution screen with impingement plates is identified at level “b". Instead of a distribution screen this layer could also be a frame with impingement plates or cones. The top view of the grid to move the particles to the loading holes as shown in figure 5 is identified at level “c” as cross section in figure 14. The bars or wires or screen or cover plate with slots for the area corresponding with the area between the vessel tubes is drawn at level “d” (figure 2 shows a top view of “d” as a cover plate with slots). For clarity the grid “c” is drawn above the loading plates, screen or cover plate “d”. During use grid “c” is located on top of the loading plates, bars, wires or screen “d”. The loading plates in this drawing are connected to the filling tube and are identified as “e” (figure 1 shows a top view of one loading plate with one loading hole for one tube). For clarity reasons the devices identified as “d” and “e” are drawn above each other. In use the top surface of the loading plate at level ”e” and the top surface of the bars or wires or screen or cover plate with slots at level “d” are at the same level( see figure 3 for a top view of “d” and “e” combined). The tubes of the tube assemble are drawn at level “f”, in this case as tubes in a tubesheet. For clarity the tubes of the tube assembly is drawn at a distance below the level of the loading plates “e”. In use the bottom surface of the loading plates should be on top of the tubes of the tube assembly.

Examples of the invention

Examples are given for loading of particles in tube assemblies in vessels as are 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 of the tube a spring is installed at 0.2 m from the bottom end of the reactor tube 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 bottom outage 0.2 m particles per tube 10 Kg inner diameter 0.039 m triangle tube pitch 0.063 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. On the top of each vessel tube a loading plate of 44 mm diameter is axially centred on the tube. The plate has an 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 the plate with an loading hole of 17 mm and centring mechanism with a top view and cross section.

1. Plates assembled in circle segments

The 9000 plates as shown in figure 1 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.

An integrated loading and cover plate with 90 loading holes of 20 mm diameter and slots of 2 mm as shown in figure 3 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 stiff straight wires or small bars as shown in figure 5 is put on the integrated loading and cover plate. On the four sides of the grid as shown in figure 5 40 mm high partitions are mounted. A top view of the filling assembly is shown in figure 6.

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 minutes 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 figures 2-6 with partitions around the screen. Ninety closed round 44 mm plates are mounted in the distribution screen at locations corresponding with the tube openings. A 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 loading is moved to the second filling assembly. 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. 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. 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 that are not allowed in the tubes fall directly in the loading hole. This can be prevented by installation of 90 circular impingement plates of 20 mm diameter above the loading holes.

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. 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 as shown in figure 3 and described in example 2 the filling assembly as shown in figure 2 is used. 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 (see figure 1 for the top view) 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.

Outage 0.7m

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 are installed corresponding with the circular openings of the cover sheet (see figure 1 top view for the top view and figure 7 for the cross section of a loading plate filling tube assembly installed in the top of a vessel tube). Similarly to example 2 the 90 vessel tubes are loaded with catalyst to at least 0.7m below the loading plate. Figure 8 shows the catalyst loaded into the filling tube. The cone is pulled upwards in figure 9. Thereafter the filling assembly is removed as shown in in figure 10.

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 required to fit the shape of the vessel tube assembly.

b) Outage 1.2 m

Loading plates with a loading hole of 20 mm connected to a 1.2 m filling tube with inner diameter of 22 mm (see figure 11 for the top view and cross section) are installed in 90 vessel tubes corresponding with the circular openings of the cover sheet. 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 (fig 12). 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.

In 90 reactor tubes a catalyst sensor is installed 1.5 m below the top of the tube. The sensor actuates a loading hole closing device that is put on top of the tube. 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 1.5 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.

In case particles conduct electricity a low voltage wire isolated from from the metal tube wall can be put in the tube to where the outage should start. As soon as the particles reach the wire a current will flow via the metal reactor tubes that actuates the loading hole closing device.

Particle dust and small particles are vacuumed from between the vessel tubes.

5. The catalyst loaded dust and small particle free with no or short tube outage A screen with wires of 0.9 mm at a distance of 6 mm is punched in a rhombus shape with equal sides of 700 mm with 60/120 degrees angle. In that screen at a 63 mm triangle pitch 121 holes of 16mm are punched. The wires in the hole are punched downwards. On the downwards punched wires the 44 mm round plate with 17 mm loading hole as shown in figure 1 is mounted using 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 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 (see figure 13 for a half tube sheet covered with screens and plates). On the screen a grid of stiff straight wires shaped as in figure 5 for the 121 (instead of the 90 of figure 5) loading holes in the shape of the screen is put on the screen.

Catalyst from two big bags containing 900 kg of catalyst each is fed to two vibrating screens outside the reactor after the first 20 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. The catalyst is slid by the grid of stiff straight wires over these screens manually or mechanically, Every six minutes the 121 tubes of one screen are loaded and the hose with outlet device is moved to the next screen.

After 6 minutes the screen with 121 plates and grid is moved to the other half of the reactor and dust and small particles are vacuumed. 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 dust and small particle free with no or short tube outage

This is a modification of example 5. No plates with loading holes are installed in the screens. Instead round impingement plates of 44 mm ate installed 70 mm above the screen corresponding and covering the loading holes (of the screen) and the tube openings. In this way catalyst cannot fall directly in the reactor tube and is forced to move via the screen. In this way catalyst dust and small particles can be removed before entering the tube.

Claims

A device for directing particles to inputs of pipes of a pipe collection, comprising a plate with a filling hole, the filling hole being smaller than the inputs.

A device according to claim 1, characterized in that a valve is provided under the plate with a filling hole.

A device as claimed in claim 2, comprising a filling line which is connected to the filling hole and which can be introduced into the entrance of the pipe, wherein the valve is provided at the lower end of the filling pipe and is movable along the axis of the filling pipe.

A device according to claim 3, characterized in that said valve is movable between an open and closed position, wherein in the open position the valve has a distance to the filling pipe that is larger than the maximum particles and in the open position this distance is smaller than the particles .

A device according to claim 4, characterized in that said valve has a conical shape.

A device according to any of claims 2 to 5, characterized in that said valve is movable upwards for adjusting the closed position.

A device according to any of claims 2 to 6, characterized in that said valve is attached to a rod that is movable upwards.

A device according to any one of the preceding claims, comprising a filling pipe which is connected to the filling hole and which can be introduced into the inlet of the pipe, characterized in that it comprises a provision for bringing the filling pipe under vacuum.

A device according to claim 8, wherein the device comprises a hose with a conical end that can be connected to the hole of the plate.

A device according to claims 3 to 9, characterized in that said filling pipe is telescopically composed of two or three pipes.

A device according to any of the preceding claims 2-10, characterized in that control means are provided which close the hole after a predetermined amount of particles have been charged.

A device according to claim 11, characterized in that the control means comprise a sensor which measures the loading height of the particles.

A device according to claim 12, characterized in that said sensor measures the electrical conductivity or the (dielectric) permittivity of the charged particles.

A filling device for directing particles to inputs of pipes from a pipe set, comprising a plate with a plurality of filling holes, the positions of the filling holes corresponding to the positions of the inputs and the filling holes being smaller than inputs, characterized in that the plate surface sieving means are provided between the filling holes.

The filling device according to claim 20, wherein the screening means have openings smaller than the particles to be loaded.

22. Filling device as claimed in claim 21, wherein the screening means are built up from a construction of wires, rods, a mesh, or a plate provided with bores.

23. Filling device according to one of claims 20-22, wherein the holes are provided with one or more of the measures from one of claims 1-13.

Filling device according to any of claims 20-23, characterized in that above the plate a grid is provided with rigid wire or rods, the grid shape of which corresponds to the positions of the holes in the plate, and means are provided for moving the schedule.

25. Filling device according to claim 24, wherein the grid is provided on the underside with soft and flexible material in the form of the grid.

A filling device according to any of claims 20-25, wherein a distribution plate is provided above the plate with openings larger than the particles to be loaded.

The filling device according to claim 26, wherein the positions of the distribution plate corresponding to the positions of the inputs of the pipes of the pipe set do not contain any openings.

Filling device as claimed in any of the claims 20-25, wherein above the plate there is provided a grid in which at the positions corresponding to the positions of the inputs of the pipes of the pipe set there are provided plates which do not contain any openings.

Filling device according to one of the claims 28, wherein at the positions corresponding to the positions of the inputs of the pipes of the pipe set a cone is provided with a bottom surface equal to the opening of the inputs of the pipes.