FR2775438A1 - Cryogenic rectifying column construction procedure - Google Patents

Abstract

The procedure uses modules, each made from a section of an inner structure (1) enclosed in a section of an outer structure (5) and assembled on side to make a column of the required height. The inner and outer structures are fitted together by inserting each inner structure horizontally into an outer one, e.g. using a system of rollers (11) and rails (31), after which the two structures are fixed together to form a module.

Description

 The present invention relates to a method of constructing an elongated interior structure of large dimensions, surrounded by an exterior structure, said interior structure being a fluid confinement structure intended to form at least part of an installation for supplying fluid.

 The invention applies more particularly to the construction of air distillation columns, the height of which can reach 60 meters, surrounded by their support frames.

 On a production site, such a column, the verticality of which must be perfect to ensure the smooth running of the distillation process, is surrounded by a frame which supports the column and all or part of its equipment, the frame being covered with an external sheet metal protection.

 Until now, for large distillation columns, that is to say whose dimensions do not allow transport, the column and its frame are built or delivered separately on site, then erect all or part of the frame into which the column is subsequently introduced. Such a construction process is complex and poses many problems of assembling the frame, the column and its equipment, in particular to respect the verticality constraint imposed on the column.

 Such a construction method also poses safety problems in particular because of the heights at which people can be brought to work.

 The invention aims to remedy the problems mentioned above and, in particular, to provide a method of constructing an interior structure of large dimensions er.tourée an exterior structure, perme = - both on the one hand an assembly quick on site meeting the verticality constraint of the column, and also allowing pre-assembly in the workshop before transport to site.

 To this end, the subject of the invention is a method of constructing an elongated interior structure of large dimensions surrounded by an exterior structure, said interior structure being a fluid confinement structure intended to form at least part of a fluid supply installation, characterized in that n modules are constructed by assembling for each of the modules a section of the interior structure with a corresponding section of the exterior structure, these n modules being intended to be assembled on site to constitute the structure interior surrounded by the exterior structure.

According to particular embodiments, the method can include one or more of the following characteristics
- At least one section of internal structure is introduced into the corresponding section of external structure by threading, in particular by moving it on rails provided in said section of external structure disposed substantially horizontally, then these two sections are joined
- We introduce and then position, identically and parallel to a predetermined longitudinal axis of the exterior structure, each interior structure section in the corresponding exterior structure section before joining these two sections
the ends of sections of external structure and of internal structure are respectively provided with means for guiding adjacent sections, and, after having positioned the section of internal structure with respect to the section of external structure of a first module and secured these two sections , for an adjacent module
the internal structural section is introduced into the corresponding external structural section,
by means of the respective guide means, the interior structure section and the exterior structure section of said adjacent module are placed respectively in the extension of the interior structure section and of the exterior structure section of the first module,
- the two sections of external structure are aligned,
- the inner structural section of said adjacent module is positioned relative to its outer structural section and these two sections are joined
- At least part of their equipment is fitted with at least two adjacent sections of internal structure, when the corresponding modules are placed in line with one another, before separating these modules
- for each module, construction is completed by placing a protective sheet metal sheet on the corresponding section of external structure, except at least in the areas of connection to the other modules
- the internal structure is a distillation column
- the external structure is a support frame
- successively assemble the n modules from the lower module to the upper module to erect the internal structure on site
- the verticality of the interior structure to be ensured on site
the lower module is positioned in such a way that said longitudinal axis of the corresponding section of external structure is vertical, and
- successively assemble the following modules above the lower module
- The verticality of the interior structure to be ensured on site, at least one section of interior structure is temporarily separated from the section of exterior structure of a module erected to ensure the verticality of said section of interior structure; and
- the interior structure is finished with, in particular by connecting the equipment of the adjacent interior structure sections, and
- we finish installing the protective sheet metal.

The invention will be better understood on reading the description which follows, given solely by way of example, and made with reference to the appended drawings, on these:
- Figures 1A to 1D are schematic perspective views of two halves of a large air distillation column (Figures 1B and 1D) and two halves of its frame (Figures 1A and 1C), constructed for the implementation of the construction method according to the invention,
FIG. 2 is a diagrammatic view on a larger scale of the circled part II of FIG. 1A,
FIG. 3 is a schematic perspective view illustrating the threading of the lower half of the column into the lower half of the frame to form a module,
- Figure 4 is a schematic end view of the module of Figure 3, illustrating the positioning of the lower half of the column in the lower half of the frame
FIG. 5 is another schematic view at the end of the module of FIG. 3, illustrating the fixing of the skirt of the lower half of the column on the half of the corresponding frame,
FIG. 6 is a schematic side view, illustrating the connection between the upper half of the column and the upper half of the frame, and
- Figures 7 and 8 are schematic perspective views respectively illustrating the installation of dishes on the longitudinal posts of the frame and on the column.

 FIGS. 1A to 1D schematically represent two sections of an air distillation column about 60 meters in length and two sections of its frame, constructed for the implementation of the construction method according to the invention.

 A lower half 1 and an upper half 3 of an air distillation column, of generally cylindrical shape, as well as the corresponding lower 5 and upper 7 halves of its frame, of generally parallelepipedal shape, are arranged substantially horizontally in a workshop. .

 Each half l and 3 of column rests on two transverse support cradles 9 spaced apart and whose longitudinal positions relative to each half of column are as described below. These cradles 9 are provided with pads linked to rollers with axes substantially orthogonal to the longitudinal axes of each half of the column. A metal protective belt 13 surrounds each half of the column at each cradle 9.

 The half l of column (FIG. 1B), which comprises the medium pressure part and the vaporizer-condenser, not detailed in the figures, is extended, at its lower end (on the left in FIG. 1), by a cylindrical fixing skirt 15 terminated by an annular flange 16 for fixing. The column half 1 comprises at its upper end means 17 for guiding the upper half 3.

 These guide means 17 comprise on the one hand an inner sleeve 19 welded in the upper edge 20 (on the right in FIG. 1B) of the half 1 and protruding from this edge, and on the other hand four radial lugs 21 fixed, by example by welding, regularly on the outer surface of the half 1. These tabs 21 each comprise a part projecting longitudinally relative to the upper edge 20. This projecting part has an internal guide surface 22 inclined radially outwards in s '' longitudinally halfway 1 apart.

 The column half 3 (FIG. 1D) is provided in the vicinity of its upper end (on the right in FIG. 1D) with two fixing lugs 23 symmetrical and transverse with respect to the longitudinal axis of the half 3.

These tabs 23 each have an orifice 25 with an axis parallel to said longitudinal axis.

 The frame (Figures 1A and 1C) is a metal frame comprising four longitudinal posts 27 connected, on each face of the frame, by crosspieces 28 and diagonal braces 29. The two halves 5 and 7 of frame each rest on four legs 30 adjustable height. Longitudinal rails 31 are arranged on the inner surface of the lower face (in FIGS. 1A and 1C) of each half 5 and 7 of the frame.

 The upper end (on the right in FIG. 1A) of the frame half 5 is provided with means 32 for guiding the frame half 7. These guide means 32 are composed of four pyramid trunks 33 extending longitudinally each section or lower half of the longitudinal post 27.

 As shown schematically in Figure 2, these pyramid trunks 33 have different dimensions.

Typically, a first pyramid trunk has a length (as seen in Figure 2) of 200 mm, a second has a length of 150 mm and the other two have a length of 100 mm. Conjugated openings not visible in FIG. 1C are formed inside the lower ends (on the left in FIG. 1C) of the upper sections or halves of the longitudinal posts 27 of the half 7.

 The upper face (on the right in FIG. 1C) of the frame half 7 comprises three substantially horizontal crosspieces 35. The lower and upper crosspieces 35 are provided with central orifices 37 with axes parallel to the longitudinal axis of the half 7.

 The bottom of the frame half 5 (on the left in FIG. 1A) is provided with vertical and horizontal crosspieces, delimiting inside the frame an area for fixing the annular flange 16 of the skirt 15.

 Half 1 of column and half 5 of frame are assembled to constitute a first module, as described below.

 Firstly, the horizontality of the longitudinal axis of the frame half 5 is ensured by varying the height of the feet 30. This positioning can be ensured by using levels or another conventional technique for those skilled in the art.

 We then introduce half of the column 1 into the half of the frame by threading by rolling the runners there on the rails 31, using a winch 47 connected by a cable to the lower end (on the left in FIG. 3) of half 1.

 Half of the column is placed longitudinally in the half of the frame 5 so that the two cradles 9 are each facing the crosspieces of each of the large faces of the half l, and such that the skirt 15 is a few millimeters crossbars from the bottom of the half 5 (left in Figure 3). The longitudinal positions of the cradles 9 with respect to the column half 1 were therefore chosen, by carrying out adequate measurements, to obtain this result.

 Five screw jacks 49 are then placed at each cradle 9, or ten jacks in total between half 5 of the frame and half 1 of the column.

 As illustrated in FIG. 4, for each cradle 9, a vertical cylinder 49 is disposed between the half 1 and a crosspiece of the large upper face (in FIG. 4) of the half 5 of the frame, and two horizontal cylinders are each arranged between the half of the column and a crosspiece of a large lateral face of the half 5 of the frame. The internal ends of these three jacks 49 are supported and are welded to the belt 13 surrounding the half 1, and their external ends are fixed to the associated crosspieces of the half 5.

 Two vertical cylinders 49 are moreover arranged between the lower face of the cradle 9 and a cross member of the large lower face (in FIG. 4) of the half 5 of the frame. Their upper ends are fixed to the cradle 9 and their lower ends on the half 5 of the frame. Then the skids are removed there under the two cradles 9 of the column half 1, as shown in FIG. 4.

 The half 1 is then positioned relative to the half 5 so that their longitudinal axes are parallel and that they have a chosen and determined relative position. This relative position can be determined using a sighting device or using another technique which is conventional for those skilled in the art.

 This relative position can be modified by playing on the settings of the jacks 49. Preferably, it is such that the half 1 is disposed substantially in a central position in the half 5.

 Once the relative positioning of the halves 1 and 5 has been completed, these two halves are joined together, for example by pointing the nuts of the jacks 49.

 The annular flange 16 of the skirt 15 is then welded, over its entire circumference, as shown diagrammatically in FIG. 5, on the crosspieces of the bottom of the frame half 5 to finish securing the halves 1 and 5.

 Half of the frame and half of the column of the first module are then positioned and fixed relative to each other.

 For the relative positioning of the upper half 3 of the column in the upper half 7 of the frame in order to assemble the second module, the procedure is as follows.

 It ensures, in a similar manner to that used for half 5 of the frame, the horizontality of the half 7 of the frame, then the column 3 half is threaded into the half 7 of the frame as described for the first module. There are ten screw jacks 49 in a similar manner to that described for the lower module and a rod 57 (FIG. 6) is mounted, using nuts, between each leg 23 of the half 3 and the cross member 35 opposite the half 7.

 Each rod 57 passes through an orifice 25 and an orifice 37, and nuts secure one of the ends to the corresponding lug 23 and the other end to the corresponding cross 35.

 It is then possible, possibly using a technique similar to that used for the first module, to carry out a relative pre-positioning of the respective longitudinal axes of the half 7 and the half 3.

 We then place, thanks to the guide means 17 and 32, the upper halves 3 and 7 respectively in the extension of the lower halves 1 and 5. For this, we put on the one hand the trunks of pyramid 33 in the conjugate openings of upper halves of the posts 27, proceeding in decreasing order of length (as seen in FIG. 2) of the pyramid trunks, and on the other hand the sleeve 19 in the lower part (on the left in FIG. 1) of the half 3 column, so as to leave a play of a few millimeters between the opposite ends of the lower and upper halves of column and frame. The rods 57 and their nuts make it possible to adjust the distance between the two column halves.

 One then ensures, by means of an aiming device or by using another conventional technique for those skilled in the art, and by playing on the height of the feet 30 supporting the half 7 of the frame, the alignment of the halves 5 and 7.

 Then position, in a similar way to that used for the first module, the half 3 of column in the half 7 of frame, so that the longitudinal tudinal axis of half 3 is parallel to the longitudinal axis of half 7, and in such a way that the relative coordinates of these two axes are the same as the relative coordinates of the two corresponding axes of the first module.

 Once this positioning operation has been completed, half of the column 3 and half 7 of the frame are permanently secured, by pointing, for example, the nuts of the jacks 49 and the rods 57.

 We then weld metal plates on the opposite ends of the two column halves and the two frame halves to freeze the relative adjustment of the upper and lower modules. Thus, each half of the longitudinal post 27 (FIG. 7) carries dishes 59 at the ends inside the frame of its longitudinal faces outside the frame. The outer surface of each half of the column receives eight dishes 61 (FIG. 8) distributed regularly at its end adjacent to the other half of the column. The dishes 59 and 61 of the lower and upper modules are arranged one opposite the other. Each plate 59 and 61 has a part, projecting longitudinally relative to the element of the module on which it is fixed, one edge of which bears on an edge of the plate fixed opposite to the other module.

 We therefore fixed, identically for the lower module and then for the upper module, the column sections with respect to the longitudinal axis of the frame, with the axis of each column section parallel to the axis of the section of corresponding framework.

 We then equip half 1 of column and then half 3 of column by mounting the respective piping and instrumentation devices.

 The lower and upper modules being aligned, the mounting of the parts of this equipment close to the opposite ends of the two modules is carried out by ensuring their alignment, for example by using temporary connection sleeves.

 The protective sheet metal is placed for each module, except at least in the connection parts of the two modules, then the two modules are separated, for example by using jacks.

 There are then means for protecting the open ends of the column, its equipment and its framework, for example watertight hoods.

 The lower and upper modules are then ready to be transported to an industrial site. The dimensions of these modules, less than 30 m, allow them to be transported by conventional means.

 The assembly of these modules on site is carried out as described below.

 The lower module is erected by placing the bottom of the half of the frame (on the left in FIG. 1A) on feet of adjustable height arranged, for example, at the four corners of the bottom of the frame. Thanks, for example, to a sighting device, or any other conventional technique for those skilled in the art, the verticality of the longitudinal axis of the half of the frame is ensured.

 The longitudinal axis of the column half 1 being parallel to the longitudinal axis of the frame half 5, by modifying the respective height of the feet on which the frame half 5 rests, it is easy to ensure the verticality of the half 1 of column.

 We then freeze the adjustment of the lower module relative to the floor of the industrial site, then we place, for example with cranes, the upper module above the lower module, guiding the lower part of the upper module <to the left on the 1C), thanks to the guide means 17 and 32. The pyramid trunks 33 are made to penetrate successively, in decreasing lengths, into the conjugate openings of the longitudinal pole halves 27 of the half 7 of the frame and by making the sleeve penetrate 19 in the column 3 half.

 When the dishes 59 and 61 of the lower and upper modules are in contact, the preset made in the workshop has been reconstituted, ensuring the proper alignment of the two column halves. The longitudinal axis of the column is therefore arranged vertically.

 The halves 1 and 3 of the column and the halves 5 and 7 of the frame are then welded by filling in the weld bead with the few millimeters provided between the upper and lower modules. We connect the equipment of the lower module and the upper module, then we finish installing the protective sheet metal.

 The method according to the invention therefore makes it possible to pre-assemble in the workshop a distillation column of large dimensions and its framework in transportable modules, and allows, on site, rapid vertical assembly meeting the vertical constraints imposed on the distillation columns.

 The construction of each module can also be carried out directly on site.

 According to a simplified variant, it is possible, after threading the column halves 1 and 3 respectively in the frame halves 5 and 7, to temporarily fix the column halves 1 and 3 in the frame halves 5 and 7 after positioning relative less precise than in the previous construction process. We then proceed to a decoupling on site, to ensure the verticality of each half of the column of an erected module, then to a final joining. Thus, we can erect the first module, separate the lower halves 1 and 5, ensure the verticality of the half 1 of the column, permanently secure the lower halves 1 and 5, then place the second module above the first and proceed in a manner analogous for the latter.

 We can also first place the second module on the first erected module, then proceed with the separation operations half column / half frame, vertical positioning half column, and final attachment half column / half frame for the two modules.

 In other variants, it is also possible to pre-equip the column halves 1 and 3 and / or the frame halves 5 and 7 before proceeding with the introduction of the column halves 1 and 3 into the frame halves 5 and 7.

Claims (12)

 1. A method of constructing an elongated large internal structure surrounded by an external structure, said internal structure being a fluid confinement structure intended to form at least part of a fluid supply installation, characterized in that that n modules are constructed by assembling for each of the modules a section (1, 3) of the interior structure with a corresponding section (5, 7) of the exterior structure, these n modules being intended to be assembled on site to constitute the structure interior surrounded by the exterior structure.  2. Method according to claim 1, characterized in that at least one section (1, 3) of internal structure is introduced into the section (5, 7) of corresponding external structure by threading, in particular by moving it on rails ( 31) provided in said section (1, 3) of external structure disposed substantially horizontally, then these two sections are joined.  3. Method according to claim 2, characterized in that one introduces and then positions, in an identical and parallel manner with respect to a predetermined longitudinal axis of the external structure, each section (1, 3) of internal structure in the section ( 5, 7) of corresponding external structure before joining these two sections.  4. Method according to claim 3, characterized in that the ends of sections of external structure and internal structure are respectively provided with means (17, 32) for guiding adjacent sections, and in that, after having positioned the section ( 1) of internal structure with respect to the section (5) of external structure of a first module and joined these two sections, for an adjacent module  the section (3) of internal structure is introduced into the section (7) of corresponding external structure,  - By means of the respective guide means (17, 32), the section (3) of internal structure and the section (7) of external structure of said adjacent module are placed respectively in the extension of the section (1) of internal structure and section (5) of external structure of the first module,  - the two sections (5, 7) of the external structure are aligned,  - Positioning the section (3) of internal structure of said adjacent module relative to its section (7) of external structure and these two sections are joined (3, 7).  5. Method according to claim 4, characterized in that at least part of their equipment is equipped with at least two adjacent sections (1, 3) of internal structure, when the corresponding modules are placed in the extension l one from the other, before separating these modules.  6. Method according to any one of claims 1 to 5, characterized in that for each module, the construction is completed by placing a protective sheet metal on the section (5, 7) of corresponding external structure, except at least in the connection areas to other modules.  7. Method according to any one of claims 1 to 6, characterized in that the internal structure is a distillation column.  8. Method according to any one of claims 1 to 7, characterized in that the external structure is a support frame.  9. Method according to any one of claims 1 to 8, characterized in that successively assembles the n modules from the lower module to the upper module to erect the interior structure on site.  10. Method according to claims 3 and 9 taken together, the verticality of the interior structure to be ensured on site, characterized in that  the lower module is positioned in such a way that said longitudinal axis of the section (5) of corresponding external structure is vertical, and  - The following modules are successively assembled above the lower module.  11. Method according to claim 9, the verticality of the internal structure to be ensured on site, characterized in that at least one section (1, 3) of internal structure is temporarily separated from the section (5, 7) of external structure a module erected to ensure the verticality of said section (1, 3) of interior structure.  12. Method according to any one of claims 9 to 11, characterized in that  - the interior structure is finished with, in particular by connecting the equipment of the adjacent interior structure sections (1, 3), and  - we finish installing the protective sheet metal.