This invention relates to an improved apparatus and method for inserting inserts into channels of a catalytic reactor. Such inserts may carry catalytic material.
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 catalysed, for example combustion, steam methane reforming and Fischer-Tropsch synthesis; these may all be used in a Gas-to-Liquid conversion process. Different types of catalytic reactor are known for GTL conversion process, for example slurry bed reactors, fixed bed reactors and compact reactors. Compact reactors comprise a multiplicity of channels extending through a reactor block, so providing a large surface area for heat exchange within a different volume of reactor. In a compact reactor the catalyst is provided on a surface and the reagents are brought into contact with that surface. Coating walls of the channels with catalyst material is feasible, but to maximize the volume of the reagents that is brought into contact with the catalyst, the channels would have to be very small. It has therefore been suggested that the catalyst may be mounted onto one or more metal structures, which may therefore be referred to as catalyst-carrying inserts, that are introduced into each of the reactor channels. Each insert may be of substantially the same length as the channel into which it is inserted.
For example such an insert may be a honeycomb structure, a finned structure, or may comprise one or more corrugated foils. Such inserts provide a large surface area for catalyst within a small volume, and the insert may have sufficiently high voidage that the flow of reactants through the channel is not unduly impeded. In addition, if there is a risk that the catalyst may become spent during use, the useful lifetime of the reactor as a whole can be readily increased by simply replacing the catalyst inserts.
A large reactor may define several thousand reactor channels, so that insertion of the 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 insert is typically only slightly less than that of the channel itself, to minimise the extent to which the reactants may bypass the insert. Furthermore, ceramic coated inserts are highly abrasive and so difficult to handle. Because of manufacturing tolerances there is inevitably a risk that an insert may become jammed during insertion, and an automated system for inserting inserts should be able to cope with this problem.
An apparatus for inserting catalyst supports into reaction channels is described in WO 2010/046700 (CompactGTL plc), but an improved apparatus that can operate more rapidly, and more reliably deal with any jammed inserts, would be desirable.
According to the present invention there is provided an insertion apparatus for inserting at least one insert into each of a plurality of reactor channels, the apparatus comprising:
means to support a magazine at a feed position, the magazine being configured to locate a multiplicity of inserts;
a transport mechanism defining at least two support channels each configured to hold a single insert, and means to transport each support channel repeatedly between an input location adjacent to the feed position and an output location;
a feed mechanism to feed one insert from a magazine at the feed position into the support channel of the transport mechanism at the input location;
a transfer mechanism for transferring an insert from the output location of the transport mechanism into a reactor channel; and
an alignment mechanism to ensure that the insert that is being transferred into a reactor channel is aligned with the reactor channel.
The transport mechanism may define a multiplicity of support channels which are arranged to pass through at least one intermediate location between the input location and the output location, and arranged such that the support channels that hold an insert are moved stepwise between successive locations.
The transport mechanism separates the input location from the output location, and so makes more rapid operation feasible, as an insert can be fed into one of the support channels simultaneously with insertion of an insert into a reactor channel. If the transport mechanism defines a multiplicity of support channels which pass through such intermediate locations, then it provides a buffer against any delay in the provision of inserts at the input location, by virtue of inserts at each intermediate location; for example when an empty magazine is replaced by a full magazine, the time taken to perform that replacement need not affect the insertion process, as the transport mechanism may be actuated to move forward through a plurality of steps without stopping, until the next insert reaches the output location.
The present invention is applicable to any reactor block in which there are a multiplicity of reaction channels into which inserts such as catalyst-carrying 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.
In one embodiment the transport mechanism comprises a rotary support structure having an axis of rotation and defining a multiplicity of support channels each configured to hold a single insert, the support channels being at locations that in transverse cross-section define a regular polygon centred on the axis of rotation. In one embodiment the support channel at the input location is diametrically opposite the support channel at the output location. For example the axis of rotation may be horizontal, the input location being above the axis of rotation and the output location being below the axis of rotation. The rotary support structure may be a cylindrical drum with eight support channels equally spaced around its periphery. The drum may rotate within a cover which ensures that inserts cannot fall out of the support channels as the drum rotates. The dimensions of a support channel may be selected to ensure the insert can easily slide along the channel, so for example the width of the support channel would preferably be at least 0.2 mm greater than the width of the insert.
The apparatus may comprise a guide element for guiding the movement of an insert as it is transferred into a reaction channel. The alignment mechanism may therefore 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, preferably a digital camera. Such a digital imaging device may be combined with a light source. 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 in use the insert is configured to pass. The aperture may be tapered along its length, and/or comprise a rollers, so that the insert is slightly compressed during passage through the guide element.
The magazine may define a multiplicity of grooves or chambers, wherein each groove or chamber is sized and configured to locate one 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 may be highly abrasive it is preferable both for the integrity of any 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 insert is in the form of a single item prior to insertion, the magazine may contain a stack of inserts on top of each other, and on each operation of the insertion apparatus one of the inserts is fed from the magazine into the support channel at the input location.
The transfer mechanism may comprise a pushing member to push an insert into the reactor channel. The pushing member may act on an insert in or adjacent to the output location. For example the transfer mechanism may comprise a linear actuator to move the pushing member.
The transfer mechanism may comprise other means for transferring the insert, for example one or more resiliently-mounted rollers in contact with the insert may be rotated to move the insert. The initial step of transferring the insert out of the support channel at the output location of the transport mechanism may be such that the insert falls out of the support channel into a position from which it is then transferred into the reactor channel. Alternatively the output location of the support channel may be aligned with the reactor channel sufficiently well that the insert can be pushed directly out of the support channel and into the reactor channel, for example through a guide element.
The transfer mechanism may be arranged to transfer the insert into the channel at an insertion speed which is constant, or at an insertion speed which varies during the course of the insertion. For example the insertion speed may be slow as the front end of the insert is transferred into the open end of the reactor channel; once the front end of the insert is within the reactor channel, the insertion speed may be increased. The insertion speed may increase continuously, or stepwise. Additionally or alternatively the transfer mechanism may be arranged to apply a variable force to the insert in the course of the insertion. In particular the force may be gradually increased, either continuously or stepwise, as the length of the insert within the channel increases.
The pushing member may comprise a pushing rod with an end face which may be configured to abut the insert, in use. The end face may be made of resilient plastic. The insertion mechanism may incorporate a sensor to monitor the force that is exerted on the insert. This enables a jammed insert to be detected.
Furthermore, according to the present invention there is provided a control system for controlling the insertion apparatus described above, 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 with 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 determine the position of 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 that reactor.
Moreover according to another aspect of the present invention there is provided an apparatus for removing an insert from a reactor channel. The removal apparatus may be associated with the insertion apparatus described above, and be activated if an insert becomes jammed before it has been fully inserted. A removal apparatus, suitable for removing an insert which is only partly inserted, comprises a cam which when actuated secures the position of the insert within a guide element; this may be operated in conjunction with means for withdrawing the guide element from the reactor, and thereby withdrawing the insert from the reactor channel.
An alternative removal apparatus suitable for use if the insert becomes jammed leaving only a short length protruding, for example less than 20 mm or less than 10 mm, comprises a fixing bar with a self-tapping screw at one end, and a frame defining a socket to fit the end of the insert, the socket having a tapered mouth, and defining an aperture at the opposite end of the frame, the self tapping screw being adapted to extend through the aperture to project within the socket. If the insert is partly projecting, the frame would be moved forward with the screw retracted so the end of the insert fits within the socket, and the screw would then be pressed on to the end of the insert while being rotated so that the screw engages with the insert. The screw and the frame would then be retracted, pulling the insert with them. This removal mechanism is also suitable for use if the insert is fully inserted into a channel. In this case the frame would be moved forward with the screw retracted until the socket is adjacent to and aligned with the end of the channel; the screw would then be pressed on to the end of the insert while being rotated, so that the screw engages with the insert; the screw would then be withdrawn, pulling the end of the insert into the socket; and then the screw and frame would be retracted together, pulling the insert with them.
As mentioned above the insert may comprise a honeycomb structure, a finned structure, or may comprise one or more corrugated foils. An insert consisting of a stack of corrugated foils and flat foils would preferably be bonded together before insertion, for example being spot welded together. The insert may occupy most or all of the length of the channel, although alternatively it may occupy only part of the length of the channel. Such inserts are typically of length at least 50 mm, more preferably at least 150 mm; and of a cross-sectional shape and size that just fits within the channel. Such inserts provide a large surface area for catalyst within a small volume, and the insert may have sufficiently high voidage that the flow of reactants through the channel is not unduly impeded. The invention is equally applicable to inserts of different structures, for example an insert comprising a metal foam or a metal mesh. In each case such a metal structure may be coated with catalytic material, typically in conjunction with a ceramic support coating.
The invention, in another aspect, provides a method of inserting inserts into channels of a chemical reactor using such an insertion apparatus. The method may further comprise the step of pushing a second insert through the guide element into the same channel, where a channel is required to accommodate two inserts end to end. In one such situation a channel contains both a catalyst-containing insert and an insert that does not contain a catalyst.
The pushing member may have 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. The pushing member may incorporate a force sensor, and operation of the insertion mechanism is stopped if the measured force exceeds a threshold. The threshold may be varied during the insertion of each insert.
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
It will be appreciated that the invention is applicable to a wide range of different reactors, of the type that may be referred to as a compact catalytic reactor, with multiple flow channels for two different fluids. By way of example,
The foils may be fabricated from a steel alloy that forms an adherent surface coating of aluminium oxide when heated, for example an aluminium-bearing ferritic steel such as iron with 15% chromium, 4% aluminium, 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 emphasised that
An automated insertion apparatus 30 is shown in
Referring now to
In a starting position, shown in
As indicated in
When the required insert 20 has been inserted into each channel 17 in the row, the gantry 34 is retracted away from the face of the reactor block 10, and the camera 43 is moved forward; the robot arm 32 then moves back along the gantry 34 to the starting position shown in
Referring now to
Referring in more detail to
At the same time as the insert 20 from the bottom position is being inserted into the channel 17, an insert 20 is pushed into the rectangular slot 60 at the top of the rotary drum. This entails the spring-loaded holding block 58 being released, and a pneumatically actuated pusher blade 62 pushing down on the inserts 20 in the magazine 38, as indicated by the arrow S, so ensuring the insert 20 is fully located within the rectangular slot 60. The right-hand half (as shown) of the rotary drum 50 is surrounded by a close-fitting cover 64, so ensuring that as the rotary drum 50 rotates the inserts 20 do not fall out of the rectangular slots 60.
When the magazine 38 directly above the rotation axis of the rotary drum 50 is empty, the pusher blade 62 is withdrawn, and the magazines 38 are moved along to the right (as shown) so that the next full magazine 38 is in the position directly above the rotation axis of the rotary drum 50.
Referring now to
The insertion rod 56 includes a pressure sensor 66, whose signals are provided to the computer 35. This enables the computer 35 to detect if the channel 17 is blocked, or if the insert 20 jams during insertion. The insertion rod 56 can be arranged to move the insert at a speed which varies, starting at a slow speed until the leading end of the insert 20 has entered the channel 17, and then speeding up. If a problem is detected, then the computer 35 ceases the insertion operation, and withdraws the insertion rod 56. The problem may be detected from an increase in the signals from the pressure sensor 66. The threshold that is taken to indicate such a problem may also vary during insertion, increasing as a greater length of insert is within the channel. If no such problems arise, then when the insert 20 is fully inserted the insertion rod 56 is withdrawn, which may be carried out at full speed. The apparatus can then moved on to the next reactor channel 17.
As shown in
If, when a blockage or a jam is sensed, part of the insert 20 is within the portion of the guide channel 54 below the snail cam 70, then the insert 20 can be removed. Firstly the pneumatic cylinder 74 moves the actuator rod 73 so the snail cam 70 pivots, as indicated by the arrow T, so the serrated surface of the snail cam 70 comes into contact with the insert 20, and presses down on it. The gantry 34 is then withdrawn, moving the robot arm 32 and with it the guide channel 54 away from the face of the reactor block 10. The snail cam 70 clamps the insert 20 to the guide channel 54, and the shape of the snail cam 70 is such that the greater the tension in the insert 20 the greater is the clamping force. Hence the insert 20 is pulled out from the channel 17. The pneumatic cylinder 74 is then extended so that the snail cam 70 turns in the opposite direction, so it is no longer in contact with the insert 20; the insertion rod 56 may then be actuated to push the insert 20 out of the guide channel 54, into a storage space for rejected inserts 20. The robot arm 32 is then returned to the operating position, and the insertion procedure continues at the next channel 17.
Referring now to
If a partly-projecting insert 20 is to be removed from a channel 17, the frame 82 would be moved forward with the screw 86 in the retracted position (as shown), so the end of the insert 20 fits within the socket 83. The control rod 85 would then be operated to press the screw 86 onto the end of the insert 20 while the screw 86 is turned, so that the screw 86 engages with the insert 20. When the screw 86 reaches the engaged position, the removal device 80 is firmly fixed to the insert 20. The removal device 80 would then be retracted, pulling the insert 20 out of the channel 17. The insert 20 can then be disconnected from the removal device 80 by unscrewing the screw 86, returning the screw 86 to its retracted position, so the insert 20 is no longer fixed in the socket 83.
The removal device 80 is also suitable for use if an insert 20 is fully inserted into a channel 17, but is to be removed. In this case the frame 82 would be moved forward until the socket 83 is adjacent to and aligned with the end of the channel 17. The screw 86 would then be turned while being pressed on to the end of the insert 20, so that the screw 86 engages with the insert 20 and projects beyond the mouth of the socket 83. When the screw 86 is in the projecting position, it firmly engages the insert 20. The screw 86 would then be withdrawn to the engaged position, pulling the end of the insert 20 out of the channel 17 and into the socket 83. The removal device 80 would be retracted as described above, pulling the insert 20 completely out of the channel 17.
It will be appreciated that the computer 35 would be initially 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. In the course of operation the computer 35 keeps a record of those channels 17 into which an insert 20 has been inserted, and also keeps a record of those channels 17 into which it was not possible to insert an insert 20. Hence the operator can be provided with details relating to blocked or mis-sized channels that will require manual attention when the remaining channels 17 in the reactor block 10 have been automatically filled. This information can then be presented to an operator.
It will be understood that the insertion apparatus 30 is described above by way of example only, and that it may be modified in various ways while remaining within the scope of the present invention. For example the insertion apparatus 30 uses a rotary drum 50 as a transport mechanism to move support channels (rectangular slots 60) repeatedly between an input location adjacent to the feed position and an output location; the rotary drum 50 may be replaced by a different transport mechanism such as a belt or chain which may pass around rollers, the belt or chain carrying support channels to locate inserts 20.
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.
If the reactor is one in which both an exothermic reaction and an endothermic reaction take place in separate channels, for example a steam methane reforming reactor in which there are reactor channels for combustion and reactor channels for steam methane reforming, the different sets of channels may be accessible from opposite sides of the reactor. Therefore, two automated insertion apparatuses 30 as described above may be used together, one at either side of the reactor block, one inserting catalytic inserts for the exothermic reaction and the other inserting catalytic inserts for the endothermic reaction.
Analogously, even if all the reaction channels require the same catalytic insert, for example in 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 30 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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1110913.9 | Jun 2011 | GB | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/GB2012/051273 | 6/7/2012 | WO | 00 | 12/24/2013 |