NL2015683B1 - A method of performing a cleaning operation in a tube system, and a device for use in the method. - Google Patents
A method of performing a cleaning operation in a tube system, and a device for use in the method. Download PDFInfo
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- NL2015683B1 NL2015683B1 NL2015683A NL2015683A NL2015683B1 NL 2015683 B1 NL2015683 B1 NL 2015683B1 NL 2015683 A NL2015683 A NL 2015683A NL 2015683 A NL2015683 A NL 2015683A NL 2015683 B1 NL2015683 B1 NL 2015683B1
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Abstract
A method of of performing a cleaning operation in a tube system using a pig, said tube system comprising a manifold tube comprising a wall provided with two tubes branching off. According to the invention, the two tubes are connected using a device introduced in the manifold, said device comprising a connecting pipe; and the step of cleaning of the tubes comprises propelling the pig using transport fluid from the first tube via the connecting pipe to the second tube. The invention also relates to the device.
Description
A method of performing a cleaning operation in a tube system, and a device for use in the method
The present invention relates to a method of of performing a cleaning operation in a tube system, said tube system comprising - a manifold tube comprising a wall, said wall comprising a first opening and a second opening, and - a first tube and a second tube, said tubes being connected to the wall of the manifold tube at the first opening and the second opening respectively, with the manifold tube connecting the first tube with the second tube, wherein the method of performing the cleaning operation comprises the step of cleaning the inner wall surfaces of the first tube and the second tube using a pig propelled by transport fluid. A tube system comprising a manifold tube and branches connected by the manifold tube is common in the art, for example in refineries. A tube of the tube system is for example part of a heat exchanger and for proper operation it may need to be cleaned at the inside, such as to remove scale or other deposited material.
To remove deposited material such as scale, the tube system is filled with a cleaning liquid, usually water, and a pig is passed through the tube by pumping water into the tube. A problem arises at the end of the tube where it is attached to the manifold tube. There the pig has to be stopped because otherwise it would end up in the manifold tube. To this end, a device is introduced into the manifold tube before cleaning, the device comprising a stop with apertures. The stop will block the pig but does allow for the passage of cleaning liquid to the other tube via the manifold tube. By blocking the pig, it is possible to continue the cleaning operation by passing the pig through the tube in the reverse direction by reversing the direction of flow of the cleaning liquid. This process is repeated several times, such as tens or if necessary even hundreds of times. A problem with the method is that due to friction against the inner wall surfaces of the tube system, the pig tends to get hot and may be damaged when it is stopped by the stop. The forces experienced by the pig when it is stopped are usually very large because of the large volume of water behind the pig that is also stopped (water shock). The hot pig tends to get soft, and may get stuck on the stop.
As the manifold tube is usually of a larger diameter than the tubes, it can't handle high pressure as well, and thus it may not be possible to dislodge the stuck pig by reversing the flow of the cleaning liquid at a high pressure. In case of such problems, the cleaning operation has to be interrupted. This is a time consuming matter because the tube system has to be drained first, and re-filled to continue cleaning, involving a large amount of liquid.
The object of the present invention is to reduce the above problems and provide for a method that is less prone to delays.
To this end, a method according to the preamble is characterized in that a device comprising - a frame comprising - a body, and - a support connected to the body, said support being for contact with the inner surface of the manifold tube, and - a connecting pipe held by the frame, said connecting pipe comprising a first end and a second end; is used, wherein the first end of the connecting pipe is pressed at the first opening of the wall of the manifold tube towards to the first tube and the second end of the connecting pipe is pressed at the second opening of the wall of the manifold tube towards the second tube so as to provide a passage for the pig from the first tube to the second tube, and the step of cleaning of the first tube and the second tube comprises propelling the pig using transport fluid from the first tube via the connecting pipe to the second tube.
This allows the pig to be passed from the first tube to the second tube, and also in the reverse direction if this is advantageous for the cleaning operation being performed. Because the stop is eliminated the pig can't get stuck on the stop. Because the pig is not stopped by the stop, there is no water shock when the pig reaches the first opening. Only part of the tube system needs to be filled with cleaning liquid, which saves time, because currently if one tube is cleaned, all tubes and the manifold tube are filled. Because used cleaning liquid is contaminated, it can't be discharged in the sewer for environmental reasons. A further advantage of the present invention is that the amount of cleaning liquid necessary to clean a tube system and has to be processed after cleaning the tube system is reduced, saving cost.
In the present application, the term cleaning operation is not limited to the removal of solid deposits. It also includes the removal of a liquid, such as a cleaning liquid from the tube system using a pig, in which case the transport fluid will be a gas.
According to a favourable embodiment, the transport fluid is a liquid.
Cleaning operations wherein the transport fluid is a liquid is an important field of application of the invention.
According to a favourable embodiment, resilient sealing elements are used at the first end and the second end of the connecting pipe.
Thus leakage of cleaning liquid into the manifold tube can be avoided. Depending on the use of the tube system, the presence of cleaning liquid is in particular undesirable if it contains water.
This water has to be removed before the tube system can be used for production purposes. This may for example be the case for a refinery.
According to a favourable embodiment, the cleaning operation comprises a liquid removal step and the transport fluid is a gas.
This operation is often a further operation performed after a cleaning operation such as disclosed above. The liquid used has to be removed, for which a soft-bodied (foam) pig is suitable, and it can be propelled through both the first tube and the second tube. The gas will for example be an inert gas but more usually the gas will be air. If there is more than one pass through the tube system, the soft-bodied pig is preferably not be propelled in the opposite direction, but in the same direction repeatedly.
According to a favourable embodiment, the manifold tube comprises at least two pairs of tubes, each pair of tubes comprising a first tube and a second tube.
This allows for the tube system not to be completely filled with water, but only the tubes that are about to be cleaned. This strongly reduces the amount of water at any one time. Reduced amount of water that has to be processed for environmentally safe disposal of contaminants. Also, the time needed for filling and draining is reduced.
According to a favourable embodiment, at least one of the first tube and the second tube is part of a heat exchanger.
This is an important field of application of the present invention. In such a case, the first tube and or the second tube is in general in the form of a coil or serpentine.
Finally, the present invention relates to a device for use in a method of performing an operation in a tube system, said device comprising a frame, which frame comprises a support for contact with the inner surface of a tube, wherein the frame comprises - a body, and - a support connected to the body, said support being for contact with the inner surface of the manifold tube, and and the device comprises a connecting pipe held by the frame, said connecting pipe comprising a first end and a second end; wherein the distance between i) the first end and the second end and ii) the support can be varied.
Such a device may advantageously be used in the method according to the invention. The device according to this embodiment can be easily introduced in a manifold tube in a first state where the distance between i) the ends of the connecting pipe and ii) the support is relatively small. For performing the cleaning operation, the distance is increased to an expanded second state so as to clamp the device inside the manifold tube, connecting the first tube with the second tube via the connecting pipe.
The support will contact the inner wall of a tube, which for the method according to the invention will be a manifold tube. It will preferably spread the load over a relatively large surface area so as to avoid local high loads and/or deformation of the tube.
According to a favourable embodiment, the device comprises a hydraulic actuator and the distance between i) the first end and the second end, and ii) the support can be varied using the hydraulic actuator. A hydraulic actuator has the advantage that it is possible to control and/or to monitor the hydraulic pressure easily, and use this to avoid damage to the manifold tube.
According to a favourable embodiment, the body comprises - a first body section, - a second body section, and - a guide for moving the first body section and the second body section with respect to each other in a first direction for varying the distance between said first body section and said second body section; wherein each body section is provided with at least one arm, said arm comprising a first proximal end and second distal end, wherein the arm is connected - with its first proximale end hingeably about an axis that extends tangentially with respect to the first direction to one of the body sections, and - with its second distal end hingeably about an axis that extends tangentially with respect to the first direction to the connecting pipe.
Thus changing the distance between the body sections will move the ends of the connecting pipe in a transverse direction with respect to the first direction.
According to a favourable embodiment, the guide comprises a threaded spindle .
Thus the distance can be varied easily and reliably. A large radial force may be exerted, if that is necessary.
According to a favourable embodiment, the frame comprises two frame sections, each frame section comprising - one of the body sections, and - two arms, each arm comprising a first proximal end and second distal end; wherein the arms are connected with their first proximale ends hingeably about axes that extend tangentially with respect to the first direction to one of the body sections, and wherein for each of said frame sections - a first arm of said two arms is connected with its second distal end hingeably about an axis that extends tangentially with respect to the first direction to the first support section, and - a second arm of said two arms is connected with its second distal end hingeably about an axis that extends tangentially with respect to the first direction to the second support section.
This is very useful for a manifold tube that comprises a first tube and a second tube that are extending from the manifold tube at the same axial position. The first axis and the second axis of a frame section will not run parallel. This reduces the degrees of freedom of the frame, enforcing a controlled movement of the ends of the connecting pipe. The first axes may run parallel. The second axes may run parallel. The two axes of a single arm will run parallel.
According to a favourable embodiment, each frame section further comprises a support section, each support section comprising two legs, each leg comprising a first proximal end and second distal end; wherein the legs are connected with their first proximale ends hingeably about axes that extend tangentially with respect to the first direction to one of the body sections, and wherein for each of said frame sections - a first leg of said two legs is connected with its second distal end hingeably about an axis that extends tangentially with respect to the first direction to a first foot, and - a second leg of said two legs is connected with its second distal end hingeably about an axis that extends tangentially with respect to the first direction to a second foot.
Thus the load can be spread more evenly over the inner surface of the manifold tube. The first legs are preferably connected to a single first foot. The second legs are preferably connected to a single second foot.
According to a favourable embodiment, the connecting pipe comprises a harmonica shape over at least part of its length.
This allows for the angle of the pipe ends to be changed with respect to each other, which is in particular useful for a tube system where the first and second tube are connected to the manifold tube at the same axial position.
According to a favourable embodiment, the first end and the second end are provided with a resilient sealing.
This allows for pressure to be spread more evenly, lowering the local load forces on the manifold tube. It also helps to reduce leakage of cleaning liquid during a cleaning operation of a tube system according to the above method.
The present invention will now be illustrated with reference to the drawing where
Fig. 1 schematically depicts a tube system with a manifold tube comprising a device according to the present invention;
Fig. 2A and Fig. 2B show cross-sectional and longitudinal views of a detail of Fig. 1; and
Fig. 3A and Fig. 3B show two perspective views of a device according to the invention.
Fig. 1 schematically depicts a tube system 190 comprising a first tube 191 and a second tube 192 connected by a manifold tube 193. To clean the tube system 190, it is provided with a pig 194 which is propelled using a cleaning fluid 195 (usually water) present in reservoirs 196 by pump 197. Control valves 198 are provided as well.
The tubes are shown over part of their length as a single line.
The manifold tube 193 is provided with a device 100 (shown with dashed lines) according to the present invention, said device 100 comprising a connecting pipe 110 (shown with solid lines). The connecting pipe 110 comprises a first end 111 and a second end 112.
The device 100 comprises a first annular resilient sealing 121 at the first end 111 of the connecting pipe 110 and a second annular resilient sealing 122 at the second end 112 of the connecting pipe 110 .
In accordance with the method according to the present invention, the first tube 191 is connected to the second tube 192 by the connecting pipe 110 to provide a passage for the pig 194 from the first tube 191 to the second tube 192, and vice versa if the direction of flow of the cleaning fluid is reversed (indicated by the arrows along the tubes).
The first tube 191 and the second tube 192 are typically part of a heat exchanger, e.g. for refining oil which is passed through the tube system 190 while hot gas is passed at the outside thereof. This results in the formation of scale at the inner wall of the tubes, which needs to be removed periodically using the pig 194. The pig 194 is a standard pig and has protrusions for contacting the inner wall of the tubes allowing the removal of the scale.
Instead of two reservoirs 196, a single reservoir 196 may be used.
Fig. 2A and Fig. 2B each show a cross-sectional and a longitudinal view of the manifold tube 193 and demonstrate how the device 100 is used to connect the first tube 191 and the second tube 192 .
First, device 100 is introduced in the manifold tube 193. The device 100 comprises a frame 210 comprising body 220 and a support 230, said support comprising legs 231 with feet 232 at distal ends thereof. In the embodiment shown here, the legs 231 are hingedly connected at the proximal ends thereof to the body 220. At their distal ends the legs 231 are hingedly connected to the feet 232.
The frame 210 also comprises arms 240. In the embodiment shown here, the arms 240 are hingedly connected at the proximal ends thereof to the body 220. At their distal ends the arms 240 are hingedly connected to the first end 111 or to the second end 112 of the connecting pipe 110 (shown with dashed lines).
The device 100 works mechanically similar to a scissor jack screw. The body 220 comprises a first body section 220' and a second body section 220". By increasing the distance between said body sections, the device 100 is in a first state wherein the distance between the feet 232 and the ends of the connecting pipe 110 is relatively small. In the first state, the device 100 can be introduced into the manifold tube 193.
By reducing the distance between said body sections, said distance is increased, allowing for the connection of the connecting pipe 110 between the first tube 191 and the second tube 192. Then the device 100 is in an extended, second state as shown in Fig. 2B.
In the embodiment shown, the feet 232 have a radius that is similar to the radius of the inner diameter of the manifold tube 193, so as to spread the load exerted by the device when it is in the second state. Also, the resilient sealings are shaped to spread the load.
In the embodiment shown here, a guide is provided in the form of a threaded spindle 250 cooperating with the body sections. At least one of the body sections will comprise a threaded hole for the threaded spindle 250. If each body section has a threaded hole, the threading will be opposite and the threaded spindle 250 will comprise two sections with opposite threading. The distance between the body sections is changed by rotating the threaded spindle 250.
Fig. 3A and Fig. 3B each show a perspective view of an embodiment of the device 100 according to the present invention.
The device 100 comprises a wheel 301 for rotating the threaded spindle 250.
In the present embodiment, the movement of the pipe ends and the feet 232 is restricted because for each of the body sections the axes of - the legs are at an angle to each other; and - the arms are at an angle to each other.
The connection pipe 110 comprises harmonica-shaped sections to allow for minor bending of the connection pipe 110. The inner diameter of the connection pipe 110 will be at least the same and in general not much wider than the inner diameter of the first tube 191 and the second tube 192 so as to allow the passage of the pig 194 and to prevent it from getting stuck in the connection pipe 110.
Many variations are possible within the scope of the appended claims. For example, it is possible to use hydraulics instead of a threaded spindle, or even to replace legs and/or arms with hydraulic cilinders and pistons. An advantage of a screw based device is that it will not collapse. And advantage of the use of hydraulics is that the pressure can be easily monitored, making it easy not to exert too much pressure on the inside of the manifold tube 193.
Claims (14)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL2015683A NL2015683B1 (en) | 2015-10-29 | 2015-10-29 | A method of performing a cleaning operation in a tube system, and a device for use in the method. |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL2015683A NL2015683B1 (en) | 2015-10-29 | 2015-10-29 | A method of performing a cleaning operation in a tube system, and a device for use in the method. |
Publications (1)
Publication Number | Publication Date |
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NL2015683B1 true NL2015683B1 (en) | 2017-05-31 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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NL2015683A NL2015683B1 (en) | 2015-10-29 | 2015-10-29 | A method of performing a cleaning operation in a tube system, and a device for use in the method. |
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