WO2007073209A1

WO2007073209A1 - Lifting in process ranks

Info

Publication number: WO2007073209A1
Application number: PCT/NO2006/000497
Authority: WO
Inventors: Jan Silgjerd; Finn WICHSTRØM
Original assignee: Aker Kværner Engineering & Technology As
Priority date: 2005-12-23
Filing date: 2006-12-22
Publication date: 2007-06-28
Also published as: NO330543B1; NO20056159L

Abstract

It is shown a device for performing lifting operations in process racks. It comprises a first and a second crane (8, 9) and a lifting yoke (24, 25), which lifting yoke has a first and a second end and the lifting yoke is arranged to extend through the rack and is supported at each end by a respective one of the two cranes (8, 9).

Description

Lifting in process racks

The present invention concerns a device and method for performing lifting operations in process equipment racks.

The invention is first of all arranged for use concerning the rack system described in the Norwegian patent application nr. 2005 3481 submitted 15.july 2005 by Aker Kvasmer Engineering and Technology AS. This application is hereby incorporated by reference.

As it also appears from the above mentioned application, the intention is that the whole process on an offshore platform shall be arranged in racks. These can be in the order of magnitude 3-7 meters wide, 10 - 25 meters high and be equally long as the platform is wide. In the racks there are no needs for any decks, stairs or ladders. Access to the process equipment can be performed with manual remotely controlled manipulators. These can be controlled either from a position on the platform or from a control centre on shore. I addition, the access of personnel can be performed by mobile decks on which the operators are located. These decks can be suspended in bars from travelling cranes. There are preferably two travelling cranes on the platform and these can operate independent of each other or in tandem. The travelling cranes have preferably a span that is at least equally large as the breadth of the whole process area, i.e. the span is somewhat larger than the length of the rack and it is taller than the tallest process rack.

AU the equipment which is to be operated when the process is running, will be suitably placed in the outer edge of the process racks. Accordingly it would be simple for the manipulators and the persons on the mobile decks to reach this equipment.

The process racks are shaped so that the process can be defined in process sections from the function. As an example, the water treatment part of the process can be split in one or more process sections. The same can occur with the sand treatment part or the separator part. Each process section is attached to structural frames in a way that makes it possible to lift it out as one unit without it interfering with the structural integrity of the process rack. The reason to why the process is split in process sections is to make it possible to change one process section with another in a short amount of time, preferably within a period of 24 hours.

With the technology of today, a replacement of equivalent process equipment will take weeks. During that time, personnel will be present and it must therefore be put restrictions on the operation, hi many cases, the platform must stop the production. With the present invention it is, in a first aspect, aimed to substantially reduce this down time, hi some cases, it will also be possible to remotely control the whole replacement from a place outside the process area, so that the production can continue practically unhindered during the replacement.

A hydrocarbon process is designed to perform work based on information about the reservoir from which the oil and gas is exploited. The conditions in the reservoir will change over time and this change is in practice hard to predict sufficiently accurate so that the process is optimal at any time during the whole lifetime of the platform; order of magnitude 15- 30 years.

A replacement of process sections will make it more probable that the process is adjusted to the desired work in relation to the economic constraints for the enterprise, at any time. That the process sections can be replaced within a short amount of time, as mention above, will imply two things:

1. The platform will be shut down in a relatively short period, and the production loss during this period will consequently be reduced compared to the method of replacing equipment today. With traditional layout of the process, a replacement of a process section of some size will take 2-4 weeks.

2. The weight of a process section is normally in the range 5 - 150 tons. This equipment is to be put down on and retrieved from a supply boat. The sea condition in the period when the equipment is put down on the boat and new equipment is lifted off by use of the present invention will be during a predicted weather window in the magnitude 24 hours. Even in the middle of the winter, that land of "windows" will occur now and then, where these types of operations can be conducted. If the lifting operation had to be performed with a floating crane and over a period longer than 24 hours, the periods during the year where this could be performed would be reduced. In some winters it would not be possible to perform these kinds of operations.

Thus, the invention aims in a second aspect to provide replacement of process equipment at times where it otherwise not would have been possible.

Since the replacement of process equipment today is a very expensive affair, it will not be profitable to perform the replacements often. One will therefore wait until the production conditions have substantially changed and it is a lot to gain on adjusting the process to the condition of the well. This makes the process non-optimal over a certain amount of time.

In a third aspect, the present invention aims at provide more frequent replacements of process equipment so that the process can be better optimized than by the relatively infrequent replacements performed today.

The invention will now be further explained by reference to the enclosed drawings, where:

Figure 1 shows a front elevation view illustrating the device according to the present invention,

Figure 2. shows a ground plan view illustrating the device according to the present invention,

Figures 3 - 6 shows lifting of a process module out of a rack,

Figure 7 and 8 shows a first embodiment of the yoke,

Figures 9 and 10 shows a second embodiment of the yoke, Figures 11 and 12 shows a third embodiment of the yoke,

Figure 13 shows the yoke parts swung to inactive position,

Figure 14 shows a manipulator arranged on a yoke part and,

Figure 15 shows a work platform arranged on a yoke part.

Figure 1 shows a front elevation of a process rack 1 that in three levels 2, 3, 4 contains process modules 5, 6, 7. The process modules can contain a collection of different components or be one equipment unit, for example a pressure tank. In the process area there can be a number of racks arranged with a certain distance between them, as it is described in the above mentioned NO 2005 3481. Figure 2 shows a ground plan view of the same devices as in Figure 1.

In the process area it is arranged a crane system. The crane system consists of two portal cranes 8, 9, arranged to move over the whole process area. The cranes 8, 9 are in their basic structure built in a conventional way with two portal frames 10, 11 (see also Figure 2) and a traverse 12. In the traverse, traverser carriages 13, 14 are arranged (se also Figure 2). From the traverser carriages 13, 14 elongated bars 15, 16, 17 extend. The bars can for example be telescopic. In the bars 15, 16, 17 mobile decks 18 and several manipulators 19, 20 are suspended. The traverse carriages, bars, platforms and manipulators are arranged so that they can pass each other and thereby be placed in different positions in relation to each other. In addition, each crane is equipped with one or two lifts (not shown) so that the cranes in a common lift can lift modules up to 150 tons. The portal cranes 8 and 9 can be equipped equally or different, but are in principle built in the same way.

The two cranes 8, 9 are equipped with wheels 21 that run on not shown rails. The cranes 8, 9 have different width and height, so that the first crane 8 runs on a railway with smaller track width than the second crane 9. The second crane 9 is tall enough to pass over the first crane 8. Thereby, the two cranes can pass each other (provided that the bars in the second crane 9 and the equipment suspended in these are drawn away from the path of the first crane 8). The traverse 12 of the second crane 9 has in this relation a boom 22, 23 on one or both sides into which the traverser carriages 13, 14 can be run when the cranes are passing each other. The cranes are placed in the Ex zone, and it is therefore placed an overpressure room (not shown) on the crane where all the electric equipment is mounted.

I connection with the lifting of process sections out of the racks, and to facilitate a complete replacement during the desired 24 hours, it is important to be able to handle pipe flanges in an effective way, so that these operations do not become critical on the time line for the progress.

In this connection, a manipulator will be equipped with a tool that grabs each of the two pipe ends that are to be bolted together, either with compact flanges or conventional flanges. The manipulator tool clamps the pipe flanges against each other sufficiently strong so that the flange surfaces lay plan towards each other and so that the centre line in one of the pipes are in line with the centre line of the other. The force that is needed to perform this operation is a hydraulic force generated by equipment (not shown) on top of the traverse 12.

The manipulator is shaped so that it, in the next step, can hold one of the pipes and rotate the other in relation to the first. The rotation is controlled manually and until the bolt holes are on line so that it is possible to push the bolts in.

Pushing in the bolts, mounting of nuts and tightening to the right torque is done by the manipulator or manually while the pipes are held in position. This way of mounting flanges does not have any dimensional limits.

The manipulators 19, 20 could also be used to loosen single components, such as electronic and pneumatic instruments, transport these to a given place on the platform and then collect a corresponding single component of same type and install this on the same place. This will be a well suitable form of maintenance that will contribute to keep down the maintenance costs. The manipulator, which is a manually remote controlled tool, can perform said operations either from a place on the platform or from a place outside the platform, for instance on an operation centre on shore. The manipulator will be equipped with the necessary instrumentation and control logics to control itself towards the goal, grip it and handle the single components or otherwise manipulate single components. Appropriately, the manipulator is controlled from one of the work platforms 18, where an operator can be situated. The operator can relocate the platform 18 to an appropriate place for visual surveillance. The manipulators can also be equipped with a camera to give the operator access to a place that is not easily seen from the platform.

A method and a device for lifting out a larger process unit or process section will now be explained by Figures 3 - 6. By this device, it is possible to lift out a process section even when the clearing around the object to be lifted out is small.

Figure 1 shows the portal cranes 8 and 9 with mounted lifting yokes. Each yoke consists of two yoke parts 24, 25. These are either mounted rigidly or have been picked up and coupled to the crane immediately before the operation. In Figure 2 it is shown two parallel yokes, each consisting of yoke parts 24, 25, as shown from above. For smaller components and in narrow places, a yoke that goes in at a single lifting point only can be used, while two lifting yokes are used to lift large components. The yoke parts 24, 25, as will be explained below, can be connected inside the module 3.

The cranes 8, 9 are positioned so that the traverses 12 are placed on each side of the process rack. Each of the cranes runs into position with one or two yoke parts 24, 25 that hangs down in telescopic bars 17 from a respective traverser carriage 13. Each of the cranes 8, 9 pushes the said two or four yoke pars 24, 25, as described above, into the process rack from respective sides, by displacing the yokes along their longitudinal axis relative to the bars 17, until the ends meet and are locked to one another so that the yoke parts constitute one or two yokes with a moment stiff connection. In Figure 4 the two lifting yoke parts 24, 25 are led in to the module in a flush position and interconnected with their respective ends.

The yokes have one or more traverser carriages 26 arranged to carry the process section 6 that is to be lifted out. From the traverser carriages one or more straps 27 or other lifting device is suspended. The straps are led around the process section 6 that is to be lifted out. The component can either be lifted in the top, as shown, or the yoke parts 24, 25 can be run under the component. The yokes can be shaped so that both options are possible. This is done either by connecting the traverser carriage to a specific lifting lug on the object, or by using normal shackles, straps etc.

To relieve the object from its mountings in the rack, the yokes are lifted slightly by raising the telescopic bars 17 until the object is no longer resting on the carrying structure in the process rack 1. In stead of lifting the bars 17 to achieve this, the traverser carriage may be equipped with a hoist (not shown) that may lift the process section a sufficient distance.

Pipes and electrical connections that connect the process section 6 with the process are released during or after the process section 6 is strapped up in the two yokes.

When the process section 6 is disconnected form the process, and it is no longer resting against the carrying structure in the process rack 1, it can be transported with the traverser carriages 26 along the yokes and out of the process rack 1, as shown in Figure 5. The traverser carriage 26 is driven for instance by motors that are in engagement with a pitch rack along the yoke or a screw drive for accurate and secure positioning. The same pitch rack can also be used to drive the yoke parts 24, 25 themselves forward or backwards in relation to the bar 17.

The process section 6 is transported out of the rack so far that the point of gravity of the process section 6 is outside the rack 1 and is possible to be reached with on or more hooks 28 on one of the cranes 9. The load can now be transferred to the hooks 28. It is a critical operation when the object is to be transferred form the yokes to the hook(s) 28. This can be done either by providing two extra lifting points inside or outside the points attached to the traverser carriages 26 or by letting the hooks 28 grab the whole traverser carriage 26 and relieve this while the yoke is driven away. With the last method the whole load can be lifted away without taking a new grip, and it will be most relevant by smaller loads and only one yoke, but it can also be used with two yokes where a grip is taken in two traverser carriages 26. Alternatively, if the load is skidded out by pushing out yokes under the object, the hooks 28 may be attached to lifting lugs on the top of the process section in a conventional way.

After the process section 6 has been taken over by the hooks 28, the yoke parts 24 and 25 are disconnected and the portal crane 9 is driven to a place where the process section 6 can be lowered down to a supply boat (see Figure 6). This can take place outside the edge of the platform or through a moon pool.

A new process section could afterwards be put in place by performing the above mentioned steps in opposite order.

The yoke parts 24, 25 can be constructed in different ways. The Figures 7-12 show examples of this.

The different principles for the design of these lifting yokes are shown in the figures. Common for these are that there is provided an articulation between the yoke parts 24, 25 and the bars 17 to prevent large torques from being transferred from the yokes to the bars. In connection with the joint there is a cylinder or another actuator that can adjust the angle that the yoke part 24, 25 is pushed in to the rack with. When the yoke parts 24, 25 are in position and are locked, the cylinder is released so that the yoke may swing relative to its attachment to the bars.

In Figure 7 it is shown two yoke parts 24, 25 rotary coupled in a joint 29 to a respective bar 17. A cylinder 30 is arranged between the yoke parts 24, 25 and the bar 17 to swing the yoke part 24, 25 in the vertical plane. The yoke parts can also possibly be rotated about the axis of the bar 17. At the joint 29 there is also arranged a linear driver 31 comprising a motor (not shown) and a number of wheels 32, arranged to displace the yoke parts 24, 25 horizontally in a straight line.

At their ends the yoke parts 24, 25 are complementary shaped. In this connection the yoke part 24 has an upper part 33 that is longer than a lower part 34. In addition, the lower part has a small protrusion 35. The yoke part 25 has a lower part 36 that is longer out than an upper part 37. The lower part 37 has at the lowest a small recess 38 which is complementary to the protrusion 35.

In Figure 8 are the two yoke parts 24 and 25 interconnected. The upper part 33 of the yoke part 24 is now resting on the lower part 36 of the yoke part 25, and the lower part 36 of the yoke part 25 is resting on the protrusion 35. The cross section of the yoke parts are shown to the left in the Figures 7 and 8, and are an I-beam with double webs. The traverser carriage 26 runs with wheels on the lower flange of the I-beams.

In the Figures 9 and 10 the yoke parts 24, 25 have a circular cross section. The traverser carriage 26 runs here with wheels on the upper part of the yoke parts. Except for this, the embodiment according to the Figures 9 and 10 are in accordance with the embodiment in Figures 7 and 8.

In the Figures 11 and 12 the yoke parts 24, 25 are constituted by two rods 39 and 40, respectively. Between the rods 39, 40 there is arranged a screw spindle 41. The upper rods 39 are at their outer ends shaped so that one of the rods 39 has a section with smaller diameter that can be led into a hole in the end of the other rod 39. The lower rods are designed with opposite hooks 42, 43, which are arranged to grab one another. To provide this engagement the yoke parts 24, 25 are displaced towards each other in an upward inclination until they reach each other. Then the yoke parts are turned downwards into ahorizontal position, as shown in Figure 12.

The screw spindles 41 are preferably designed to engage with each other and form one spindle. The spindles can be used both to displace the yoke parts towards one another and away from one another, and also to displace the traverser carriage 26 along the yoke.

There are many possible solutions for attaching the traverser carriage to the object that is to be lifted, for example:

• Special lifting lugs mounted on the object and adapted to the construction of the traverser carriage, for example so that it can be manually or automatically pushed into a bolt or similar to connect the traverser carriage to the lug.

• Conventional shackle, strap or similar that is connected in lifting points or led around objects etc. (this is probably the most relevant on smaller and lighter objects)

Lighter objects can be removed from the process section by using a manipulator arm that can be mounted either directly under a telescopic bar or on the traverser carriage of the yoke, as shown in Figure 14. In these cases it will be an advantage if the platform or the arm on which the manipulator is placed on can lean on the structure on certain places. Docking stations can be designed in the racks for this purpose. Thereby, the accuracy of using a manipulator mounted on the traverser carriage can be improved.

The yokes used when objects are be taken out of the sections can, when not in use, either be disconnected with a quick release coupling or they can be tilted up as shown in Figure 13. Work platforms may be arranged directly under the telescopic bars. However, this gives a somehow limited access. If there is a need for better access, smaller mobile work platforms can be connected to the traverser carriage, as shown in Figure 15. Thereby, good access is provided about many axes.

Claims

C l a i m s

1. Device for performing lifting operations in process racks comprising a first and a second crane and a lifting yoke, which lifting yoke has a first and a second end, c h ar a c t e r i z e d i n that the lifting yoke is arranged to extend through the rack and to be supported at a respective end by one of the two cranes, and that the yoke comprises yoke parts, that while they are supported in a respective crane, are displaced substantially horizontally relative to the support in the crane, so that the yoke can be led through a rack.

2. Device according to claim 1, wherein the yoke parts are arranged to be interconnected through the rack so that they form a rigid connection for lifting purposes.

3. Device according to one of the preceding claims, wherein it comprises a traverser carriage arranged to move along the yoke.

4. Device according to one of the claims 2 — 3, wherein the yoke parts are complementary shaped so that they may be interconnected to form a moment stiff connection.

5. Device according to one of the preceding claims, wherein the cranes are portal cranes that are dimensionally shaped so that they can pass each other.

6. Method to provide lifting operations in process racks, wherein a lifting yoke is led through the process rack, that the lifting yoke is supported at each end outside the process rack, that an object to be lifted is connected with the yoke, that the object is lifted by the yoke and that the object is led along the yoke out of the process rack.

7. Method according to claim 6, wherein the yoke comprises two parts, that the two yoke parts are led from each side into the rack, that the yoke parts are interconnected at their opposite ends to form a moment stiff connection.

8. Method according to claim 6 or 7, wherein the object to be lifted after it is led out of the rack along the yoke is taken over by another lifting device, after which the yoke is pulled out of the process rack.