This invention relates to improved catalyst foil configurations and to a procedure, to an apparatus and to a method, for inserting catalyst foils into catalytic reactors.
Catalytic reactors provide an environment in which the speed and efficiency of a chemical reaction can be improved using a catalyst. Many different types of reactions can be catalyzed, for example combustion, steam methane reforming and Fischer-Tropsch synthesis; these may all be used in a Gas-to-Liquid (“GTL”) conversion process. Different types of catalytic reactor are known for GTL conversion process, for example such as slurry bed reactors, fixed bed reactors and compact reactors. Compact reactors comprise a multiplicity of channels extending through a reactor block. In a compact reactor the catalyst is provided on a surface and the reagents are brought into contact with that surface. It has been suggested to coat the walls of the channels with the catalyst. However, in order to maximize the volume of the reagents that is brought into contact with the catalyst, the channels have to be very small. It has therefore been suggested that the catalyst can be mounted onto one or more foils that are introduced into each of the reactor channels.
The provision of the catalyst on foils has a number of advantages including a considerable increase in the surface area for catalyst within a small volume, and the foils can have sufficiently high voidage that the flow of reactants through the channel is not unduly impeded. In addition, the lifetime of the reactor as a whole can be limited by the life of the catalyst, whereas, if the catalyst is provided on foils, the foils can be replaced thereby increasing the life of the reactor as a whole.
A large reactor may define several thousand reactor channels, so that insertion of the catalytic inserts can be time-consuming. The insertion must also be carried out carefully to avoid damaging the insert and to avoid the risk of obstructing the flow channel. This can be problematic because the cross-sectional area of the foil or foils to be inserted into a channel is typically similar to the cross-sectional area of the channel itself and therefore the insertion process must be carried out accurately. Furthermore, ceramic coated foils are highly abrasive and are difficult to handle. In addition, when a channel is to contain a number of separate foils that form a stack of foils, further problems arise.
The present invention is applicable to any reactor block in which there are a multiplicity of reaction channels into which catalyst inserts are to be inserted. The reactor block itself may comprise a stack of plates. For example, first and second flow channels may be defined by grooves in respective plates, the plates being stacked and then bonded together. Alternatively the flow channels may be defined by thin metal sheets that are castellated and stacked alternately with flat sheets; the edges of the flow channels may be defined by sealing strips. The nature of the first and second flow channels would depend upon the reaction or reactions that are to occur in the reactor block. For example channels for an exothermic chemical reaction may be arranged alternately in the stack with channels for an endothermic reaction; in this case appropriate catalysts would have to be inserted into each channel. For example the exothermic reaction may be a combustion reaction, and the endothermic reaction may be steam methane reforming. In other cases channels for a chemical reaction (first channels) may be arranged alternately in the stack with channels for a heat transfer medium, such as a coolant. In this case catalytic inserts would only be required in the first channels. For example the first channels may be for performing the Fischer-Tropsch reaction, and the heat transfer medium would in this case be a coolant.
The present invention has been devised in order to address and mitigate some or all of the above mentioned problems.
According to the present invention there is provided an insertion apparatus for inserting at least one catalytic insert into each of a plurality of reactor channels, the apparatus comprising: a magazine configured to hold at least one catalytic insert, a guide element for guiding the movement of the catalytic insert as it is inserted into the reaction channel, and a pushing member to push a catalytic insert out of the magazine, through the guide element, and into a reactor channel.
The apparatus may further comprise means to align the guide element with a reactor channel. In addition, the apparatus may further comprise means for monitoring the alignment of the guide element with the reactor channel. The means for monitoring may be a camera, a video camera. Alternatively, the monitoring means may use laser or ultrasound technology to monitor the alignment of the guide element.
The guide element may provide an aperture through which the catalytic insert is configured to pass, in use. The aperture may be tapered along its length, and/or comprises rollers, so that the catalytic insert is slightly compressed during passage through the guide element.
The magazine may define a multiplicity of grooves, wherein each groove is sized and configured to locate a catalytic insert. Alternatively, the magazine may define a single elongate groove in which a plurality of inserts may lie in an end to end configuration. The magazine with a plurality of grooves each sized for a single insert may be preferred as this minimizes the distance that each insert has to be pushed in order to insert it into the reactor. As the inserts are highly abrasive it is preferable both for the integrity of the catalyst on the insert, but also for the magazine, to minimize the distance that each insert has to be pushed.
As another alternative, if the catalytic insert is in the form of a single item prior to insertion, the magazine may contain a stack of catalytic inserts on top of each other, and on each operation of the insertion apparatus one of the catalytic inserts is pushed out of the magazine.
The apparatus may further comprise at least one roller configured to bear against at least one face of the catalytic insert while it is pushed out of the magazine. The roller, or rollers, may be located above the magazine so as to roll along the upper face of the insert as it is pushed out of the magazine. The downward force provided by the roller or rollers will in some cases help to prevent the catalytic insert from buckling during the insertion process.
The pushing member may comprise a pushing rod with an end face which may be configured to abut the catalytic insert, in use. The end face may be made of resilient plastic.
Furthermore, according to the present invention there is provided a control system for controlling the insertion apparatus according to any one of the preceding claims, the control system comprising: a microprocessor configured to receive data from one or more sensors, an actuator configured to control the pushing member and an actuator configured to move at least part of the apparatus to provide alignment between the guide element and a reactor channel.
One of the sensors may be a pressure sensor located on the pushing member. One of the sensors may be an optical sensor configured to confirm alignment of the insert with the channel. The actuator may further be configured to move at least part of the apparatus to provide alignment between the catalytic insert and the guide element. One of the sensors may be configured to confirm that a channel is correctly sized and not blocked. If a channel is identified that is blocked, then the control system will not attempt to insert an insert into such a channel. This will reduce the number of instances of failure of the apparatus resulting from an insert being part-inserted into a channel which is blocked or mis-sized. In addition, the control system may further comprise means for storing reactor layout information which is configured to record data from the sensor identifying blocked channels. The means for storing reactor layout information may be a memory that can be updated with further relevant data about the status of the channels in the reactor.
Moreover according to the present invention there is provided an automated method for inserting catalytic inserts into reactor channels, the method comprising the steps of: aligning the insert with a reaction channel, and pushing the insert through a guide element into the channel. The alignment may be monitored using a camera providing feedback to the alignment means.
The catalytic insert may comprise a plurality of insert elements stacked together. The method may further comprise the step of bonding the insert elements together before aligning the insert with the reaction channel, the insert may be bonded together using a shrinkwrap sheet. The method may further comprise cutting and peeling away the shrinkwrap sheet as the insert is pushed into the channel.
The method may further comprise the step of checking that the reaction channel is correctly sized and not blocked prior to the step of pushing the insert through the guide element into the channel. This step may be carried out directly before the step of pushing the insert through the guide element into the channel. Alternatively, this step may take place before the step of aligning the insert with a reaction channel. It is especially important to check that the channel is not too small for the insert as attempting to insert an insert into an undersized channel could result in a blockage that may stop the insertion apparatus.
The method may further comprise the step of pushing a second insert through the guide element into the same channel.
The method may further comprise the step of moving the guide element and pushing rod into alignment with a second reactor channel and repeating the steps described above. The method may further comprise the step of moving the magazine into alignment with a second reactor.
The insertion apparatus may comprise a plurality of pushing members and a plurality of guide elements, so that a plurality of catalytic inserts can be inserted simultaneously from the magazine. This is only feasible if the reactor channels are at well-defined separations, and it is generally preferable to insert only one catalytic insert at a time, as this simplifies the step of aligning the insert with the channel.
Where the catalytic insert comprises a plurality of insert elements stacked together, for example a stack of corrugated foils and flat foils, these may be bonded together before insertion. For example they may be spot welded together. Alternatively they may be bonded together in a temporary fashion, for example being secured together by a wrapping strip, such as a shrink-wrap sheet, or being secured together by a plastic clip or end cap; or being secured together by being embedded in a low-melting point material such as wax. It is usually desirable to remove the wrapping strip or the clip as the insert is inserted into the channel, and this may be carried out using a cutter associated with the guide element to peel the wrapping strip away or to cut off the clip. Hence the method may further comprise cutting and peeling away of the wrapping strip or the clip as the insert is pushed into the channel. On the other hand, if the insert elements are embedded in wax, which has the benefit of helping to lubricate the passage of the catalytic insert along the channel, the wax may be subsequently removed by heating the reactor block so that the wax melts.
Alternatively the insert elements that form the catalytic insert may be located in a groove or channel within a magazine, without being bonded together. If the catalytic insert is located in a groove, it may be held down when being pushed into the reactor channel to ensure it does not bow as it is pushed along; this may use rollers adjacent to the groove.
The pushing member preferably has a resilient plastic end face that abuts the catalytic insert rather than a hard metal end face, to avoid damaging the end of the insert, for example a polypropylene end face. Preferably the pushing member incorporates a force sensor, and operation of the pushing member is stopped if the measured force exceeds a threshold.
The invention will now be further and more particularly described, by way of example only, and with reference to the accompanying drawings in which:
a and 1b show views of alternative reaction channel arrangements;
Referring to
The foils may be fabricated from a steel alloy that forms an adherent surface coating of aluminum oxide when heated, for example an aluminum-bearing ferritic steel such as iron with 15% chromium, 4% aluminum, and 0.3% yttrium (eg Fecralloy™). When this alloy is heated in air it forms an adherent oxide coating of alumina, which protects the alloy against further oxidation and against corrosion. Where the ceramic coating is of alumina, this appears to bond to the oxide coating on the surface.
In an alternative example, not illustrated, the foils that provide the substrate for the catalyst may be replaced with a wire mesh or a felt sheet, which may be corrugated, dimpled or pleated. It will be appreciated that one or more catalyst inserts 20 are provided throughout the length of the reaction channel 17 where catalytic reaction is to occur. The reactor channel 17 may for example be of length 150 mm or more, for example up to 1 m, such as 600 mm; and consequently the insert 20 will be of comparable length—for example two inserts 20 each of length 300 mm might be inserted end to end in a channel of length 600 mm.
In
It is to be emphasized that
In this example it will be assumed that the corrugated foils 22 are supplied in trays or racks 30 and the flat foils 21 are supplied in trays or racks 31, for example with grooves with one foil 21 or 22 in each. Since more than one foil is to be provided within each channel 17, the first stage of the insertion process is to produce a foil stack for use as an insert 20. This may be done using a robot arm arranged to pick up appropriate foils 21 or 22 successively, and to place them as a foil stack.
Alternatively, referring now to
The foils from the trays 30, 31 may be pushed out in quick succession or at substantially the same time, in order to form stacks in the stack-forming block 32. Alternatively this may be done with just one foil from each tray 30, 31, so as to form a single stack.
As one option, the foil stacks are then pushed out of the deep grooves in the stack forming block 32 into aligned shallow grooves in a magazine plate 40 (shown in
Alternatively, each of the foil stacks is then pushed out of the stack-forming block 32 into a respective shrink-wrap tube 34, and these tubes 34 are heated to hold the foils 21 and 22 in each stack together. The shrink-wrap tubes 34 are of a material of sufficient thickness to hold the foils 21 and 22 securely together, and also to be peelable subsequently without tearing. The shrink-wrap tubes 34 are also configured to compress the stacks in the vertical direction. However, it is important that the tubes 34 do not place excessive pressure on the stack as this could result in the stack becoming mis-shapen. The resulting shrink-wrapped stacks can be subsequently loaded into a spring-loaded magazine 64 (as shown in
Once the catalytic inserts are packed, either into a magazine, magazine plate or shrink wrapped, the inserts are protected and may for example be transported to a reactor manufacturer where inserts are provided in new reactors, or to a reactor reconditioning plant where inserts are provided to replace inserts on which the catalyst is spent. The magazine, magazine plate or shrink-wrap tubes effectively form the transit packaging for the inserts. This packaging may be disposable or returnable. When the inserts arrive at the reactor manufacturer or the reconditioning plant they are then inserted using apparatus as shown in
Referring now to
Three resiliently mounted rollers 52 rest on the foil stack 20a in the groove 42 that is aligned with the insertion guide 46. Although three rollers 52 are shown the number of rollers provided is partly dictated by the length of the catalytic insert: if the insert is longer then more rollers may be used. Furthermore, the number of rollers provided is partly a compromise between the extent of the contact provided between the rollers and the catalytic insert and the radius of the rollers. Because the ceramic that coats the catalytic foils is very abrasive, fine abrasive dust may be present in the immediate vicinity of the inserts and therefore if a large number of small radius rollers is used the dust may damage the bearings of the rollers and reduce their useful lifetime. Conversely, if one large roller is used the extent of the contact between the roller and the catalyst insert is limited. For a catalytic insert of 300 mm length between two and five rollers may be used.
The support structure 44 has two degrees of freedom: up or down, and into and out of the plane of the paper as shown in
As soon as this insertion has been completed, the insertion plunger 48 is withdrawn. The rollers 52 are slightly raised up, and the magazine plate 40 is moved along so that the next groove 42 is aligned with the insertion guide 46, and the rollers 52 are lowered back into the position as shown. The support structure 44 can then be moved to align with another channel 17. When all the foil stacks 20a in the magazine plate 40 have been inserted in this fashion, the magazine plate 40 is replaced by a new magazine plate 40.
In an alternative not shown in the accompanying figures, the insertion guide may comprise one or more pairs of opposed rollers between which the foil stack 20a is pushed. These rollers may be passive, or they may be driven. The foil stack is of resilient material, and in every case the effect of the insertion guide 46 is to squeeze the foil stack 20a sufficiently to ensure that it does not catch on the edges of the channel 17 as it is inserted. The pressure sensor 51 provides further assurance of satisfactory operation, because it enables the computer controller to cease insertion if a blockage occurs.
Referring now to
The use of the insertion apparatus 60 is partly analogous to that of the insertion apparatus 45, in that the support structure 62 is moved to align the insertion guide 46 with a reaction channel 17, the accuracy of this alignment and the suitability of the channel to accept the insertion of the foil stack 20a being checked by a video camera 55. When the insertion guide 46 is aligned, the insertion plunger 48 is activated to push the foil stack 20a through the insertion guide 46 and so along the reaction channel 17. As the foil stack 20a passes through the insertion guide 46 the blade 68 ensures that the shrink-wrapped tube 34 is peeled off. When the insertion plunger 48 is withdrawn, the springs 66 ensure that the next foil stack 20a rises up to abut the rollers 52, so the insertion apparatus 60 is ready for the next insertion.
The video camera 55 and the sensor 51 on the insertion plunger 48 feed data into the controller. The controller is configured to receive data from the video camera 55 and the sensor 51 and to send commands to one or more actuators (not shown) which are configured to move the magazine 64 or the magazine plate 40 and/or the support structure 44, 62 relative to the reactor block 10. Data from the video camera 55 will confirm when the insertion guide 46 is aligned with a channel 17 and confirm that the channel is correctly sized and not blocked. It may also be used to check that the catalytic insert in the magazine or magazine plate is aligned with the insertion guide 46.
When the insertion apparatus 60 shown in
The controller also controls the movement of the insertion plunger 48. The insertion plunger 48 is actuated to push a single foil or foil stack into a channel 17. If the foil(s) experience any undue resistance, for example as a result of a blockage in the channel 17, the sensor 51 will feed back data to the control system which will alter the force used on the insertion plunger 48. If the force used by the insertion plunger 48 is excessive it can result in the foil(s) being damaged, for example by buckling. The controller can be configured to alter the force, and therefore the speed at which the foil or foil stack is pushed into the channel. For example, the controller may initiate the movement of the insertion plunger 48 with a low force resulting in the initial movement of the foil or foil stack being comparatively slow. Once the foil or foil stack is at least partly contained within the channel, the channel effectively provides support for the foil and the force on the insertion plunger 48 can be increased and therefore the speed of insertion can also be increased.
The controller is further provided with information relating to the layout of the reactor, including the number of channels into which a foil or foils need to be inserted. This reactor layout information may be stored in a memory or other suitable storage means. Location sensors can be provided that are configured to relay information to the controller relating to the channels within the reactor that have been filled. The controller uses this data to identify which channels still have to be filled. The controller sends commands to the actuators to align the insertion guide 46 and insertion rod 48 with channels that need to be filled with a catalyst foil or foils. In addition, the controller stores data from the video camera 55 indicating that a channel is not correctly sized or is blocked. This data, in combination with the information relating to the layout of the reactor, enables the controller to collate information relating to blocked or mis-sized channels that will require manual attention when the remaining channels in the reactor have been automatically filled. This information can be presented to a skilled operative to help identification of problem channels.
It will be appreciated that the insertion apparatuses 45 and 60 and the processes described above are by way of example only, and that they may be modified in various ways while remaining within the scope of the present invention. For example in the apparatus 60 the rollers 52 may be omitted, and the magazine 64 may have a top plate against which the topmost foil stack 20a rests; in this case there are windows on opposite sides of the top of the magazine 64 for the foil stack 20a and the plunger 48 to pass through. In each case the foil stack 20a is described as being pushed in by a plunger 48, but in alternative arrangements at least part of the driving force for insertion of the foil stack 20a may be provided by actively driven rollers or continuous belts on either side of the foil stack.
Furthermore, although the examples described with reference to
The apparatus can be used to introduce catalytic inserts into a new reactor or to replace catalytic inserts during reactor reconditioning. The lifespan of a reactor may be in the region of 10 years, whereas the catalyst life may be only in the region of three years. It will therefore be necessary to recondition a reactor, by providing a new set of catalytic inserts 20 three or four times within the life of a reactor.
The support structure and the size of the magazine or magazine plate may be altered according to the situation in which the apparatus is intended to be deployed. For example, if the apparatus is to be deployed on the site where the reactors are manufactured, then the support apparatus may be substantial and may comprise a plurality of insertion rods and insertion guides that are capable of providing multiple simultaneous insertions of catalytic inserts into different reactor channels on the same reactor. Conversely, if the apparatus is to be deployed as part of a reactor reconditioning, this may require the apparatus to be at least partially portable and therefore a smaller support structure and correspondingly fewer insertion rods and insertion guides will be provided.
If the reactor is a steam methane reforming reactor, the reactor channels for combustion and those for steam methane reforming may be accessible from opposite sides of the reactor. Therefore, two sets of apparatus as described above may be used together, one at either side of the reactor, one inserting combustion catalytic inserts into the combustion channels and the other inserting steam methane reforming catalytic inserts into the steam methane reforming channels.
Conversely, if the reactor is a Fischer-Tropsch reactor, there may be access to both ends of the reaction channels 17, and in this case the catalyst inserts can be inserted from either side of the reactor block. In this case, two sets of apparatus may be used simultaneously inserting catalytic inserts into the same reactor channels. This is especially advantageous in the situation where the reactor channel length is double the length of the catalyst insert. In this case, each apparatus can insert one catalytic insert into each channel.
Number | Date | Country | Kind |
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0819520.8 | Oct 2008 | GB | national |
0822531.0 | Dec 2008 | GB | national |
This application is a continuation of PCT Application No. PCT/GB2009/051415, filed Oct. 21, 2009 and claiming priority to GB Application Nos. 0819520.0 filed Oct. 24, 2008 and 0822531.0 filed Dec. 11, 2008, the disclosure of which is incorporated herein by reference in its entirety.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/GB09/51415 | 10/21/2009 | WO | 00 | 4/21/2011 |