NO134230B - - Google Patents

Abstract

arm-insulated container with a double-curved outer surface, as well as a method of manufacturing such a container and apparatus for use in carrying out the method.

Description

The present invention relates to a heat-insulated cryogenic container comprising at least a first actual container with an outer double-curved surface and a heat-insulating layer of rigid foam placed on the outer surface, where it covers at least a significant part of it.

A cryogenic container is to be understood as a suitable container

for the storage of liquids at a very low temperature, and double-curved surface is to be understood as a surface that curves in two directions.

It is generally known to coat containers with thermal insulation. as examples of prior art, reference can be made to German explanatory document no. 1 954 992, English patent no. 1 240 614 and no.

1,247,863, as well as US patent no. 3,491,910 and no. 3,504,820. However, there are problems associated with the application of foam plastic insulation on double-curved cryogenic containers of the such containers as a rule have considerable dimensions, as they are usually used for the transport of, for example, liquefied natural gas on board ships.

The present invention aims to arrive at an effective insulation for a cryogenic container of the kind mentioned at the outset, with minimal voltage breakdowns in the insulation despite the extreme temperature differences in such containers, as well as a method and an apparatus which makes it possible to apply such insulation with minimal workplace outside the container during the insulation application which usually has to be carried out in a closed room, e.g. a ship's room.

The purpose is achieved by a container, method and apparatus as specified in the patent claims.

In the following, the invention will be described in more detail with reference to the drawing, where: Fig. 1 schematically illustrates the production of a thermal insulation of a spherical container in accordance with the invention. Figs. 2 and 3 are schematic illustrations of parts of a foam deposition head which can be used in an apparatus in accordance with fig. 1. Fig. 4 is a schematic illustration of a support suitable for use in connection with the foam deposition head shown in fig. 1, 2 and 3. Figs. 5, 6 and 7 are schematic illustrations of foam welding assemblies intended to be used in connection with the foam deposition heads of fig. 2 and 3. Fig. 8 is a schematic illustration of a foam welding device intended for use in connection with the use of previously formed foam strands when carrying out the method according to the invention. Fig. 9, 10 and 11 schematically show a device for use when applying a reinforcement in connection with the apparatus in fig. 8 to obtain a reinforced, prefabricated foam strand.

Fig. 12 and 15 schematically illustrate assembly and placement

ring of the welding apparatus in fig. 8-11.

Fig. 14 is a schematic interrupted view of the construction

on fig. 1 in combination with a mechanism for applying a vapor barrier.

Fig. 15 and 16 schematically illustrate the operation of the apparatus

tet for applying a vapor barrier.

Fig. 15A is a schematic illustration of a part of the appa-

the rate on fig. 15, seen in section along the line 15A-15A in fig. 15.

Figures 15B, 15C and 15D schematically illustrate vapor barriers

during various stages of manufacture.

Figs. 17 and 18 are two schematic illustrations of an alternative embodiment of a foam application head which may be used in conjunction with the apparatus of Figs. 1. Figs. 17A and 17B schematically illustrate modifications of the method for placing the reinforcing material.

Fig. 19 is a schematic section through an embodiment

for. a joint between consecutive windings during use

section of prefabricated foam insulation.

Fig. 20 is a schematic interrupted section of insulation

posed using prefabricated foam.

Fig. 21 is a schematic interrupted section of insulation produced by applying newly formed foam. Fig. 22, 23 and 24 schematically and in cross-section illustrate alternative connections between successive strings or turns arranged in accordance with the invention.

Fig. 25 schematically illustrates the connection between isola-

tion which is located closest to the container in fig. 1 and insulation facing away from the container.

Fig. 26 and 27 schematically illustrate alternative embodiments for insulation layers according to the invention.

In fig. 1, 40 generally denotes a container with an apparatus

for applying insulation. The complete container 40 comprises a generally spherical inner container 41 which surrounds an internal space,

not shown in the drawing, for the absorption of cryogenic substances. Be-

the holder 4l has an upper or top part 42 and a lower or bottom part 43* The container 41 has a generally spherical or doubly curved outer surface 44. Between the top part 42 and the bottom part 43 there is a diametrical or generally equatorial flange 45 which extends around the container 41. An approximately cylindrical support is arranged around the container 41. The support 46 has a top part 48 and a bottom part 49 arranged around the container 41. The top part 48 of the cylindrical support 46 is in effective contact with the flange 45. The bottom part 49 of the support 46 is attached to a foundation or a deck 51 on a ship or another movable or stationary structure. The container 41 has, near the top, a protective cover 53 designed to receive lines, valves, etc. not shown in the drawing. for liquids and gases. The first or upper isolation device 55 is arranged near the top part 42 of the container 41. The isolation device comprises a cooperating combination of a guide device 57, suitably in the form of a rail which is held in a fixed position in relation to the container 41 by means of about support elements 59 arranged in the container. The elements 59 are fixed to the foundation 51. An arc-shaped support frame 6l extends from a place near the top part 42 of the container 41 to a place between the flange 45 and the container' 41 bottom part 43. The arc-shaped support frame has a upper end 62 and a lower end 63- A drive device 65 for the frame is attached to the frame 6l at a location near the guide device or rail 57* The drive device 65 is provided with a motor 66 which is in drive connection with a gear 67 located in contact with the rail 57- Near the first end of the frame 62 and in cooperative combination with this there is a storage device 69. Storage device The pin 69 comprises a pivot pin 71 attached to the casing 53 in the extension of an axis through the spherical container and at the same distance from any point on the circular rail 57. The pin 71 is passed through the bearing device 69 and is provided with a pivot bearing 73 at the end which faces away from the casing 53. The vortex bearing 73 forms rotatable connections for a power source for the supply of electric, hydraulic and/or pneumatic driving force. The storage device 69 is made with a peripheral platform 74 and an annular guide 75 in abutment against a flange 76 on the casing 53 to thereby prevent axial wobble of the storage device 69. A supply device 78 for heat insulation is movably placed on the platform 74. A material source 79 is attached near the storage device 69; a supply line 81 extends from the device 78 to a location near the frame 61 which carries a thermal insulation deposition head 82 adapted to receive foam or foam-forming material from the supply line 81 and deposit it as a continuous string in engagement with a previously applied string . The foam deposition head 82, which deposits the foam strand 83, is in operative communication with a device 84 for applying a vapor barrier and which is arranged to move at a fixed distance from the head 82. Near the bottom 43 of the container 41, another or lower isolation apparatus generally designated 86. The apparatus 86 comprises an arc-shaped frame 87 with a lower end 88 and an upper end 89, a drive device 91 for the frame attached to the upper end 89 and a storage device 92 for the frame attached approximately coaxially with the pivot pin 71• A foam deposition head 93 is movably arranged on the frame 87. A lower peripheral guide device or rail 95 is arranged on the inside of the cylindrical support 46 and cooperates with a gear wheel 96 which is stored on and driven by the drive device 91. For the storage device 92 there is adjustably attached another foam supply device 98. 99 is a supply pipe for material which is passed through the cylindrical support 46.

When using a device as illustrated in fig. 1, the upper part of the container and part of the cylindrical support are first provided with thermal insulation by first placing the application head 82 near the lower end 63 of the frame 6l. The insulation material, e.g. synthetic foam plastic, is directed from the foam source to the application head, and a continuous strand of foam is deposited around the perimeter of the support 46. The first insulating strip may be held in position by any suitable means, adhesives, brackets attached to the container support, etc. Once the first strand of plastic skin has been deposited, the following turns are applied with foam plastic and joined successively with the previous ones. When the frame 6l rotates around the container 49 while applying successive windings, the head 82 is gradually moved upwards from the lower end 63 of the frame 61 in the direction towards its upper end 62 so that insulating material is applied in the desired amount and in uniform thickness and at the desired speed. The apparatus and method require little care except for the supply of material to form the foam-shaped insulation strip. '' "■'»-*'~* r The apparatus for applying the lower insulation layer is working

in a similar manner and with the: first applied insulation strip flour being placed around the container 41 near the second or upper end 89 of the frame 8l by means of the application head 93, and strip-

the line or strand is then wound gradually downward in a direction away from the container's equatorial flange to cover a substantial portion of the container's downward facing surface. An approximately cylindrical insulation element 101 is arranged on the inner surface of the cylindrical support 46 and the space between the insulation element 101, and the spirally applied insulation is filled with insulation material 102 which can be in the form of prefabricated plates, e.g. sheets of foam plastic or foam, which are produced in connection with the application of foam-forming, hardenable materials.

A lower equatorial region 104 of the container 41 will thus not receive any direct application of insulating material. Heat to be supplied to the container 4l through the non-insulated part,

must, however, come from a considerable distance through the support element 46, the outer insulation 83 and the inner insulation 101.

Figs 2 and 3 illustrate in front view and ground view, respectively, an application head for insulation material with the welding unit removed. The apparatus in Fig. 2 and 3 is generally designated 110 and is particularly suitable for applying preformed insulating strips of foamed thermoplastic or strips with thermoplastic surfaces which can be connected to each other by heating. The apparatus 110 is shown in connection with a container wall 111. The apparatus 110 comprises a cooperating combination of a frame or support 112 which is approximately L-shaped. The frame carries a stand 113• The stand 113 interacts with

a support arm 114 which is carried by a carriage on an arc-shaped support similar to the support frames 61 and 87 in fig. 1. The arm 114 is pivotally attached to the strut 113" The strut is further, at a point between the arm 114 and 112, rotatably connected to the piston rod of a hydraulic cylinder 116 which extends between the strut 113 and the arc-shaped frame carriage. The hydraulic cylinder serves to adjust the upright 113 in relation to the support arm 114 and likewise the frame 112 in relation to the wall 111. The frame 112 carries a drive motor 118 which is in operative connection with a first drive roller 119. The motor 118 is preferably an electric, hydraulic or pneumatic motor with gear head. Another drive roller 120 and a third

drive roller 121 is rotatably supported on the frame 112. Several belts 122 preferably with a V-shaped profile engage in suitable grooves in the rollers 119, 120 and 121, so that a large friction surface is provided. The axes of the drive rollers 119, 120 and 121 are essentially coplanar and lie in a plane approximately parallel to the wall 111. The drive rollers 119, 120 and 121 project down from the frame 112 in the direction

away from the strut 113. A first side guide roller 123 is arranged approximately opposite the first drive roller 119. Another guide roller 124 is arranged opposite the drive roller 121. The axes of the rollers 119 and 123 are approximately coplanar and likewise the axes of the rollers 121 and 124. The roller 123 is rotatably supported in a pin 125. The pin 125 is carried by a shaft 126 which in turn is carried in a bearing 127 attached to the frame 112. A tension device or spring 129 serves to press the bearing 125 and the roller 123 in the direction of the drive roller 119" The roller 124 is mounted in a similar unit designated 131

which presses the roller 124 in the direction of the drive roller 121. The rollers 123 and 124 can rotate freely about their axes and can move away from or in the direction of the associated drive roller, but their axes of rotation are kept approximately parallel to the axis of rotation of the associated drive roller. A roller adjuster 132 is attached to the frame 112. The roller adjuster conveniently consists of a fluid-driven cylinder with a movable rod or arm 135; the rod 135 is operatively engaged with a pressure roller frame 136 which carries two pressure rollers 137 and 138 which are rotatably stored in the frame. The pressure rollers 137 and 138 have axes of rotation that lie in a plane approximately normal to the plane containing the axes 119, 120 and 121 and normal to a plane containing the axes of the rollers 123 and 124. The three sets of rollers thus form a channel where the drive rollers 119 > 120 and 121 form one side of the channel, the rollers 122, 123 and 124 form the opposite side, and the rollers 137 and 138 form the top of the channel which is generally designated 141. According to fig. 2, a first foam element 142 is arranged in the channel 141. The foam element 142 extends in one with a foam element 142A, and a fiber-shaped insulation mat 144 is arranged between the element 142A and the container wall 111. A guide roller assembly 1.45 is attached to the arm 114 and can desired is used to keep the application unit 110 at a distance from the wall 111. A sensor member 146, which e.g. a single-pole, double-acting electric switch, a pneumatic pilot valve or the like, is attached to the assembly 145 and serves, in a manner not further illustrated in the drawing, to regulate the position of the application

the head 110. When the rollers 147 1 guide roller assembly 145 are no longer in contact with the wall 111 over a predetermined distance, it is done is; appropriate correction. A welding assembly 150 which is schematically indicated in fig. 3, is attached to the frame 112. Fig. 4 schematically illustrates the relationship between the arms 114 and the setting element 116 as well as a carriage which can be moved along the arc-shaped frame. Reference numerals 153 and 154 denote side parts of an arc-shaped frame, similar to the arc-shaped frames 61 and 87 in fig. 1. The frame element 153 is provided with a first rack 155, while the element 154 is provided with a similar rack 156. A frame carriage 158 is arranged between the two frame elements 154 and 153. On the frame is stored a first gear 159 and another gear l6l. The gears 159 and 16l mesh with the racks 155 and 156, respectively. The gears 159 and 16l are driven at the same speed by means of a motor not shown. The frame 158 carries an adjustably mounted plate 163. The plate 163 is connected to the frame i58 by means of two support elements 165 and 166, both of which are designed with adjustable lengths. The support members may be of any desired construction, but preferably they are designed as scissors and are operated by means of a motor not shown which is controlled by the sensing member 146 which is shown in fig. 2 and 3-Fig. 5, 6 and 7 are three schematic illustrations of the welding head which is indicated schematically in fig. 3 and here denoted by the reference number 150. The welding head 150 comprises a frame 150 made with two parallel slots 171 and 172. A wedge-shaped heating plate 174 is attached to a carriage 175 which is slidably mounted in the slots 171

and 172. A setting body 177, which e.g. a pneumatic or hydraulic cylinder, is rigidly connected to the frame 170 and is further connected to an arm 178. For practical reasons, the arm 178 is made U-shaped and is designed to move the carriage 175 to one or the other of the two extreme positions which is allowed by the slots 171 and 172. A vertical strut l8l is also attached to the frame 170. The stand 181 carries an upper pressure roller 182 intended to rest against the upper side of a foam element 141B. "Upper part of the foam element" is to be understood as the part facing away from the last applied strip and away from the heating plate. The upright 181 and the frame 170 further carry a separating roller 184 designed to maintain a desired distance between a newly applied foam strip such as the foam strip i4lc

and the foam strip l4lb which is about to be applied. The separator roller 164 is arranged approximately parallel to the roller 182. As shown in fig. 5 and 6, the rollers 182 and 184 are made with bearings l82a and l84a which divide the roller 1 into two parts and allow the surface of the roller to come into contact with the foam strip 141b without the use of a blank bearing which in certain cases could get lost in a wall, e.g. the wall Ill indicated on fig. 6. An edge guide roller 186 is rotatably stored in the frame 170 and extends on one or the other side of the heating plate and forms a positive guide of the frame from an already applied strip, e.g. the strip 14lc in fig. 6. Preferably, the frame 170 is pivotally connected to the frame 112 by means of a pivot pin 188. The pin 188 allows rotation about an axis which lies in a plane approximately parallel to the plane through the heating plate. The pin 188 in turn carries a horizontally extending pin 189 which allows movement of the frame 170 in a plane parallel to the plane of the heating plate and around an axis normal to the plane of the heating plate. A setting device 191, which e.g. a hydraulic cylinder operated with a suitable pressure fluid may conveniently serve to adjust the frame 170 relative to the frame 112.

Fig. 8 illustrates an embodiment of the foam supply device 78 in Fig. 1 and is generally denoted 200. The supply device 200 is a welding mechanism which is particularly suitable for use in connection with prefabricated foam plastic blanks or strips and is suitable for joining or butt welding the strips in extension of each other and with their end surfaces butting against each other. The welding assembly 200 comprises a frame 201 on which two drive rollers 202 and 203 are rotatably mounted. The drive rollers 202 and 203 are driven by means of a suitable motor not shown in the drawing. Another pair of drive rollers 208 and 206 are arranged at a distance from the frame 201

and is operated separately by means of a suitable device not shown. The two pairs of drive rollers have approximately parallel axes and are arranged on one side of the frame 201. Preferably each pair of rollers, i.e. the rollers 202 and 203, are arranged so that they are pulled springily towards each other in a similar way to the rollers 205 and 206 and are adapted to receive therebetween a suitable sized strip or blank of prefabricated foam. The frame 201 is made with slots 208, 209 and 210. The slots 208, 209 and 210 are parallel to each other and serve to slide a carriage 212. The carriage 212 can be freely slidably adjusted between the feed rollers 202 and 203

and the discharge rollers 205 and 206..1 the carriage 212 is eri's slot 214 which extends in a direction approximately at right angles to the direction of the slots 208, 209 and 210. A heating plate 215 is slidably mounted in the slot 214. A first pair of guide rollers 217 and 218, whose axes are approximately parallel to the axis of the roller 202, are arranged near the rollers 202 and 205. -Another pair of guide rollers 219 and 220 are rotatably attached to the carriage 212 and are arranged on the opposite side of the rollers 217 and 218. The axes for the rollers 219 and 220 are parallel to the axes of the rollers 217 and 218. The rollers 203 and 206 and the rollers 219, 220 form one side of a passage 221 for foam insulation. The other approximately parallel and opposite side is formed by the rollers 202 and 205 and the rollers 217 and 218. The other sides of the passage or channel 221 are formed by the frame 201. Arranged in the channel 221 is shown a first foam strip 221a and a second foam strip 221b, the ends of which abut the plate 215» The plate 215 is connected to a suitable setting device, e.g. a pneumatic or hydraulic cylinder which allows setting the plate at least partially inside the channel 221 or retracting the plate so that it is completely outside the channel 221. For the sake of clarity, the setting device is not shown in the drawing. A device 223 for yielding tightening, which e.g. a spring, is connected to the carriage 212 and the frame 201 so that the carriage 212 is pulled in the direction of the infeed rollers 202 and 203. The frame 201 has a planar extension 224 on the side facing away from the infeed rollers 202 and 203 and in the vicinity of the outfeed rollers 205 and 206 and is destined to receive material from them.

When using the device 200, a foam strip is fed, which e.g. the strip 221a, to the feed rollers 202 and 203. The strip is fed through the channel 221 with the heating plate 215 pulled out just before the end of the strip passes the plate 215* The end of the strip 221b is fed between the rollers 202 and 203 and fed to a place between

the guide rollers 218 and 220. The plate 215 is introduced between the strip ends, and the strip ends are pressed into contact with the plate by exerting pressure against the strip 221b either manually or by means of the rollers 202 and 203. The carriage 212, due to its spring bearing, allows an efficient self-centering of the plate between the ends of successive strip elements. When the ends of the foam plastic elements are heated to a desired temperature that allows the elements to stick together, the plate 215 is quickly pulled out, and the

softened ends of the foam plastic elements are pressed into contact with each other. As a result of heat release to the surroundings, the thermoplastic material between the foam strips hardens so that these are effectively welded together. Appropriately, the welding is carried out in such a way that the longitudinal axes of the two strip pieces do not run exactly in extension of each other, but form a small angle corresponding to the curvature of the surface to be covered by the foam strips. Such an angular position can generally be easily achieved manually or by adjusting the guide rollers 217 and 218. By providing for such a deviation from a rectilinear course, a stress concentration at the weld seam is avoided when the strip is wrapped around the curved surface as indicated at 8l in fig. 1.

Fig. 9 schematically shows a suitable embodiment of an apparatus 3om which can be used for reinforcing the insulation. The apparatus is generally designated 230 and is intended to be placed at the upper part of the apparatus 200 in fig. 8. The apparatus 230 comprises a frame 231 which can be made integral with or releasably attached to the frame 201 of the apparatus 200. To illustrate how the apparatus 230 should be arranged in relation to the apparatus 200, the rollers 205 and 206 in fig. 9 indicated by dashed lines. The frame 231 carries several heating elements designated 233 > 234, 235 and 235a. The heating elements 233, 234, 235 and 235a are generally rectilinear, elongated elements. The elements 233 and 234 are arranged near the surface of frames. 231, while the elements 235 and 235a are located at a vertical distance from the base plate and in a position generally corresponding to the bottom and one side of the channel 221 in the apparatus 220. In the vicinity of the heating elements 233 and 234 a roller 236 is arranged which is rotatably supported on the frame 231. Another roller 237 is arranged near the heating elements 235 and 235a. The roller 236 is made with disk-shaped projections 236a and 236b which are provided with grooves along their periphery, <p>g which projections are arranged near the heating elements 233, resp. 234. The roller 237 is made with a similar pair of projections, each of which is located in the vicinity of the heating element 235 and 235a, respectively. One of these projections 237a is shown.

A guide roller" 238 cooperates with the rollers 236 and 237 to press

a foam strip against the roller 237. A similar guide roller cooperates with the roller 236, but is not shown in the drawing. Close to the rollers 236 and 237 cooling means are arranged, e.g. air nozzles 239, which cooperate with the roller 236 and air nozzles 241 in the vicinity of the roller 237. In the vicinity of the air nozzles and at a distance from the rollers 236 and 237 are

two sets of guide rollers 242 and 243 are arranged. The rollers 242 and 243 form an extension of the channel 221 in fig. 8 and has axes that are parallel to the rollers 205 and 206.

Fig. 10 schematically illustrates the roller device seen in

section along the line 10-10 of the device 230 in fig. 9 and shows the relative position of the rollers 236, 237 and 238 together with a fourth roller 238a which is not shown in fig. 9" The axes of the four rollers are generally coplanar, and the rollers are arranged to form a passage 221c through which a foam strip, such as the strip 221d, can be inserted. An elongate reinforcing element 245, soni e.g. a filament or a yarn, is fed into the groove on the projection 237a on the roller 237. The reinforcing element 245 is suitably supplied from a suitable supply 246 such as e.g. a coil, drum or other suitable device .not shown in the drawing. Similar reinforcing elements are supplied to the grooved projections 237b, 236a and 236b from supplies not shown in the drawing.

A continuous 3cm strip coming from apparatus 200 is heated at locations corresponding to heating elements 233, 234, 235 and 235a. The foam plastic strip melts or softens to an easily deformable state, but at a temperature below that at which significant decomposition takes place. Reinforcement fibres, such as fibers 245, pressing., into the foam surface softened by heat at. using the projections 236a, 236b, 237a and 237b respectively on the rollers 236 and 237- In general, foam plastic that is suitable for use as thermal insulation will be relatively soft at room temperature. Under such conditions, the softened foam will harden and effectively enclose the pressed-in reinforcement filaments. :.Such reinforcement can. consist of glass fiber bundles or metallic monofilaments such as e.g. smooth fence wire depending on the need for the construction being produced. Preferably, such reinforcement elements are added to the part of the foam strip which will form the outside of the finished construction and in a part of the strip which will lie between adjacent windings of the insulation. In the finished construction, the reinforcement introduced by means of the projections 237a and 237b will lie on the outside of the thermal insulation, such as e.g. the outer surface of the insulation 83 in fig. 1, while the reinforcement element introduced by means of the projections 236a cg 236b will be on the underside of the foam plastic strip 8l in fig. 1. The use of such reinforcing elements is particularly advantageous when relatively large foam strips are bent over a curved surface, as the foam elements are exposed to significant tensile stresses during this bending. After forward-

position of the insulation, the reinforcement is advantageous when the insulation is exposed to stresses caused by the temperature differences between the inside and outside of the insulation.

Fig. 11 is a schematic illustration of a cross section

through a foam element and heating elements in section along line 11-11

on fig. 1 and shows the position of the heating elements 233, 234, 235 and 235a in the device 230 in fig. 9 in relation to a foam element 221d.

The figure shows how parts of the foam element indicated by the reference numbers 233a, 234a, 235b and 235c are shown collapsed or melted

tet as a result of the heating from the elements.

Fig. 12 schematically illustrates the assembly of a scour supply device 78 in Fig. 1 and a support 74. The foam supply device 78 preferably comprises an apparatus such as

shown in fig. 4, 5, 6, 7, 8, 9, 10 and 11. The device 78 is appropriately mounted in such a way that it can swing around a fixed

angle by means of a joint connection 251, e.g. performed as a ball joint, cardan joint, universal joint or a joint of one of the many other well-known designs of such joint connections. Appropriately, the link 251 is carried on a stand 252 with adjustable height, which stand can consist of a hydraulic cylinder, a frame, a rack and pinion connection or other mechanical equivalents. The height-adjustable device 252 is displaceably stored on the support 74 in such a way that it can be set in the desired position around the periphery with the displacement of a foot 253.

Fig. 13 is a schematic plan view of the support device 74 in Fig. 1 and shows a circular guide or groove 255 which receives and guides the foot 253 in Fig. 13. 12. The welding head 200 in fig. 8 with or without the reinforcement device as shown in fig.

9, 10 and 11, and supported in the manner indicated in fig. 12

and 13, serve for easy presentation of a prefabricated, continuous

equal foam strip to the application head 82 in fig. 1, while a frame such as e.g. the arc-shaped frame 61, rotates around the container 41 and allows a spiral application of thermal insulation on the container up to a place near the top 42. The remaining parts of the insulation can either be applied by making foam at the time of application or alternatively by fitting prefabricated sections.

Fig. 14 shows an interrupted view of the apparatus in fig. 1 and illustrates the relative position of the arcuate frame 61, the surface of the container 44, the foam application head 82, the insulation 83 of FIG. 1, the carriage 158 in fig. 4 and the application device 84

on fig. for a vapor barrier.

Fig. 15 and 16 are two schematic illustrations of the operation of the device 84 in Fig. 1 and 14 which serve to apply a vapor barrier and show in sequence the elements which form a vapor barrier on the surface of the insulation 83 at a rate approximately equal to the rate of application of the foam insulation. In fig. 15 and 16, 260 denotes a supply for a continuous strip of a thin, rollable vapor barrier material such as e.g. a metal foil or plastic foil to which an adhesive layer has been applied. A web-shaped foil 26l is withdrawn from the supply 260 and fed to the forming rollers 262, 263, 264, 265, 266 and 267. The rollers are arranged so that they form three pairs. The first pair consists of rollers 262 and 263; the second pair consists of rollers 254 and 265, and the third pair consists of rollers 266 and 267. The first and third pair of rollers serve as friction rollers for braking the web, while the rollers 264 and 265 are each mounted in a frame which can be displaced relative to the first and third pairs of rollers and thus allow the rollable web to be stretched near one longitudinal edge, so that the web is deformed from its planar or cylindrical shape to an extent sufficient to allow it to conform to a doubly curved surface which it must be applied to. As indicated in fig. 1, the degree of stretch or deformation required will be zero at the cylindrical skirt of the container and will increase as the application device 84 for the vapor barrier approaches the top 42 of the container 41. The suitably stretched or optionally unstretched foil or film 26la is fed to a flange-forming unit 270 which preferably consists of a shoe 271 and a guide 272 into which the shoe fits. Between the shoe 271 and the guide 272 a gap 273 is formed. The gap varies in shape from a flat slot at A to a channel-shaped profile at B. The rollable web or foil 26la is thereby formed into a channel-shaped profile 26lb. This channel-shaped profile comes into contact with the free-running rollers 274 and 275 which lie against each side of the channel-shaped profile's step as well as two free-running pairs of rollers 276 resp. 277 which comes into contact with the channel profile's flanges. The rollers 274 and 275 and the pairs of rollers 276 and 277 serve to guide and set the channel-shaped strip 26lb to the desired position at a distance from the shoe 271 and in the vicinity of the foam insulation 278. A heating element 279 is arranged in the vicinity of the foam insulation 278. The heating element 279

serves to heat the foam insulation and a thermoplastic heat-seal coating on the web 26lb facing the foam insulation. At a location indicated by the reference numeral 26le, the approximately channel-shaped web 26lb is adhered to the foam insulation 278. The channel-shaped web 26lb has a first flange 28l and a second or lower flange 282. The flange 282 is placed in intimate contact with a flange 28la on the former applied vapor barrier web and is pressed with the help of the sealing rollers 283 and 284 in contact with the thermoplastic

ke coating on flanges 282 and 28l. In the vicinity of the heat sealing rollers 283 and 284 and at a distance from the shoe 271, a device 286 is arranged which serves to bend the flanges on the web 26lb. The device 286 has an inlet end 287 and an outlet end 288. The device 286 has the form of an evenly rounded channel with significantly greater curvature at the inlet end 287 than at the outlet end 288. A free-running roller 291 is arranged near the outlet end 288

which lies in contact, against a bent edge 292 coming from the forming device 286. In the vicinity of the roller 291 on the side facing away from the device 286, there is a flange folding device 294. The device 294 has an inlet end 295 and an outlet end 296. The folding device 294 serves to fold or fold the double flange edge 292 while forming a seam 297. Near the outlet end 296 of the forming device 294 there is a free-running roller 298 which serves to further adjust the application device 84 for the vapor barrier in the desired position.

Fig. 15A schematically shows the assembly of the rollers 264 and 265

set 1 direction of lines I5A-15A on fig. 15. The rollers 264 and 265 are mounted approximately parallel rotatable in a frame 301. The frame 301 is operatively engaged with a bearing pin 302 which is attached to the application device 84. 304 denotes an adjustment mechanism

which is articulated with the frame 301 at a point located

at a distance from the pin 302. The adjustment mechanism 304 is further connected to the frame 84 at a point that is located at a distance from the frame 301.

By means of the mechanism 304, it can angle the axes for

the rollers 265 and 264 form with the axis of the rollers 262, 263, 2^6 and 267, is varied from zero to a significant

extended to stretch the track 261 to the desired extent. Too clear- ..• •

heat owes the path 261 shown as a' flat or planar path. For many purposes, however, it is desirable to use a corrugated web where the corrugations are small and have a length of from 10 to 50 times the thickness of the web and the height of the corrugation approximately corresponds to the thickness of the web.

Fig. 15B shows a section through the web 26lb seen in direction

of the line 15B-15B in fig. 15.

Fig. 15C is a section along the line I5A-15C in fig. 15 of the web 26lb and shows the shape of the flange after it has been heat sealed to an adjacent, similar web-shaped strip and passed through the forming device 286. Fig. 15D is a corresponding section along the line I5D-I5D of fig. 15 and shows the strip 26lb and the flange 282 after it has been bent by means of the forming device 294. Figs. 17 and 18 show an alternative embodiment of a head for the production and application of foamed insulation, which head is generally designated 320. The head 320 is particularly suitable for the application of foam-shaped insulation where the foam is formed immediately in connection with the application, e.g. in the form of polyurethanes, epoxy resins, phenolic foam etc. The head 320 is built on a frame 321. The frame 321 has a mounting and insertion pin 323 on its upper side. The setting pin is articulatedly connected to a support arm 324 which corresponds to the arm 114 in fig. 2 and 3- A setting mechanism 325 is articulated with the pin 323 and corresponds entirely to the setting mechanism 116 in fig. 2 and 3« A setting unit 326

is attached to the arm 324 and corresponds to the device 145 in fig. 2

-and 3. The frame 321 carries a set of rotatably supported side rollers 328, 329 and 331. The side rollers 328, 329 and 331 are generally parallel and arranged at a distance from each other with their axes approximately coplanar. A belt 333 is passed around the rollers 328, 329 and 331. A

another set of rollers 335 and 336 are rotatably supported on the frame 321.

The rollers 335 and 336 are arranged approximately at right angles to the rollers 328, 329 and 331 and are surrounded by a belt 338. The belts 333 and 338 form two adjacent sides in a channel. Drive rollers 331 and 336

is in operative connection with a drive motor 341 under intermediate coupling of a speed reduction gear 342. The output shaft 3^3 from the transmission 342 is in connection with a bevel gear 3^5

which drives the roller 331 and a sprocket which in turn drives

another sprocket 347 which is in active engagement with the roller 336.

In the vicinity of the roller 338 and at a distance from the roller 331, there is a free-running roller 3^8 which serves to support and guide a perforated cloth, e.g. of textile material or a metal wire mesh from a supply spool 351 stored on the frame 321 near the exchange 342. A mixing assembly 353 is arranged near the guide roller 348, and the mixing assembly 353 is adapted to receive suitable foam-forming materials for the production of a foamed, curable material which is fed out through an outlet pipe 354 at a location located between the longitudinal edges of the belts 333

and 338. The apparatus 320 is shown fitted with a container wall 356 on which a layer of fibrous insulation 357 is arranged, e.g. a glass fiber mat. A first inner cloth 358 is arranged between the insulation 357 and a hardened foam 359 which is fed out through the outlet line 354. A similar foam body 359a is located immediately next to the body 359. The cloth 358 and the body 359 as well as the bands 353 and 338 form a rectangular channel 1 which the foam-forming, hardenable material fills3. Appropriately, a vapor barrier 351 can be placed in the vicinity of the band 333 between the band and the foam 359" and upon curing and maturing, the barriers are attached to the foam body. Conveniently, a top fabric 362 is arranged between the band 338 and the foam body 359, which fabric represents a suitable reinforcement of the insulation layer. The top cloth 362 is suitably supplied from the supply roll 351 which is shown in fig. 18, and passes to the free-running roller 3^8 and then on the surface of the belt 338. Between the roller 335 and the roller 3^8 there is conveniently arranged a device 364 which serves to bend the edges of the cloth and which is arranged to to receive the edge of the cloth 358 and fold or fold it to the desired shape. Fig. 17A shows the shape or profile that would be desirable at point 365, as shown in fig. 17- Fig. 17A is an enlarged, interrupted view of a foam strip 359a with a top cloth 362a arranged on the upper side, and a side cloth 358a. In the vicinity of the upper part of the cloth 358a there is arranged a detachable film strip 367 which is placed between the upward facing surface 362b of the cloth 362a and a folded part 358b of the cloth 358a. This film may suitably consist of polyethylene, polytetrafluoroethylene, a hydrocarbon wax or a similar material which is not prone to adhere to the cloth or the foam body.

An alternative rigid device is shown in fig. 17B showing "an upper sheet 362b, a side sheet 358c and a film strip 368 which overlaps the upper sheet 362b and effectively prevents adjacent portions of the foam body from adhering to this area. Both devices shown in Fig. 17A respectively and 17B, allows an equalization of tensile stresses as the surface of the foam insulation near the container wall 356 cools below the temperature of the outer portions of the foam body near the vapor barrier 361.

Fig. 19 schematically illustrates a method for stress relief that can be used in connection with prefabricated foam bodies. Fig. 19 shows a deposited prefabricated foam strip 370 having an outer surface 371, an inward facing surface 372 and an upward facing surface 373 • An adjacent or upper foam strip 375 having an outward facing surface 376 and an inward facing surface 377 bore a downward facing surface J( b. The latter surface of the strip 375 has a raised portion 379, while the lower strip 370 has a raised portion 37^• The raised portion 379 of the upper strip is in contact with and is firmly connected to the upwardly facing surface 373 of the lower strip 370 at a point in the vicinity of the outward facing surface of the strips 370 and 375 - A space or unglued part 381 is located between the strips 370 and 375 in an area in the vicinity of the inward facing surface 372, resp. 377-When the inward facing surfaces 377 and 372 are cooled

to cryogenic temperatures, they will tend to contract, and the forces arising in the bonded or connected portions of the foam bodies will tend to produce cracks propagating in directions more or less parallel to the surfaces 371»376, 372 and 377 and not in the direction normal to these surfaces. Suitable prefabricated foam strips with raised portions in the desired positions can be produced by any suitable foam forming technique including cutting with a hot metal wire, sawing, milling, etc.

Fig. 20 represents in interrupted view an illustration of

an embodiment of the invention designated 390. The embodiment 390 comprises a wall 391 with an insulated surface 392, a first body of porous, fiber-shaped insulation 393 in contact with the surface 392 on the wall 391» Another fiber-shaped insulation body 39^ is placed on the surface of the wall in some distance from the body 393« Isola-

sion bodies 393 and 39^ enclose a space 395 between the bodies.

A first strip 397 of synthetic plastic material is arranged near the insulating layer' 393 at a distance from the surface 392. Another strip 39b" is arranged near the strip 397* Strip-

lines 398 and 397 are connected to each other by means of an internal

sealing or heat welding 399« The weld 399 is located near an outward facing surface 401 of the insulation which

stands of the strips 397 and 398 at a distance from the surface 392 of the wall 391* 1 distance from the outward facing surface 401, the insulation and the adjacent surface 392, a stress-relieving slot 402 is formed between the insulation strips 392 and 398. At a distance from the fibrous insulation bodies 393 and 39^ the slot 402 ends in a pear-shaped cavity 404. Fibrous reinforcing elements 406 are shown embedded in the insulating bodies 397 and 398. A metal element 408 which serves as a vapor barrier is shown arranged on the surface 401 of the insulating bodies 397 and 398.

The embodiment illustrated in fig. 20, is particular

suitable for cryogenic containers that work at relatively low temperatures. The space 395, which is located between the fiber-shaped insulation elements 393 and 39^, forms a suitable path for gaseous

the substances that escape through the wall 391, and the slot 402 with the pear-shaped termination 404 represents a tension-relieving device under the influence of a significant temperature gradient that occurs when the temperature of the wall 391 is significantly below the ambient temperature.

Fig. 21 schematically shows a section through an isolated be-

holder designated 410 comprising a container wall 411 with an external insulated surface 412. A compressible fibrous mat 413 is arranged in contact with the surface 412. The fibrous mat can suitably consist of glass fibres, inorganic or organic fibres.

The mat 413 has an external surface 414 at a distance from the wall 411.

A reinforcing fabric 415 is arranged in contact with the surface 414.

A foam insulation 417 produced at the point of use is

arranged in contact with the cloth 415 and comprising a first or lower strip 418 and a second or upper strip 419, which strips are formed of foam-forming materials in connection with the application by means of a foam application device of the type illustrated in fig. 17 and 18. Another reinforcing fabric 421 is arranged approximately centrally in the insulation 417 and lies approximately parallel to it

first cloth 415. A non-adhesive film strip 423 is arranged between the first cloth 415 and the second cloth 421 at a place which forms the connection between the strips 41B and 419- A third or outer cloth 424 is arranged approximately parallel to the first cloth 415 on a outer surface 426 of the cellular insulation 41?. A fourth cloth 427 extends from the first cloth 415 to the third cloth 424 and is embedded in the foam material, while this is applied e.g. by means of an apparatus as indicated in fig. 17 and 18. A string-shaped reinforcement 429 is arranged in the insulating body 417 in suitable places.

Fig. 22 illustrates an embodiment of a stress relieving slot designated 435. The slot 435 is located between the first insulating strip 436 and the second insulating strip 437. The strips or bodies 436 and 437 have an outer surface 438 and an inward facing surface 439. The slot 435 extends inwardly from surface 439 in the direction toward surface 438 and ends approximately midway between surfaces 438 and 439 in the form of a curved inwardly concave termination 435a.

The embodiment illustrated in fig. 22, is particularly advantageous in the event that extreme temperature variations occur, and it is desirable that any cracks should propagate in the direction towards the inward facing surface 439 and not parallel to the surface 439 or the outer surface 438.

Fig. 23 shows an alternative embodiment of a joint, generally designated 440, between successive thermoplastic bodies 441 and 442. A textile reinforcement 443 1 form of a bent

strip with longitudinal edges 444 and '445 is arranged near the outward facing surface 446 of the joint 440. The strip 443 forms an internal bead 448. The internal bead 448 is arranged in a slot 449 which has a profile 1 similar to the slot 402 in fig. . 20.

The textile reinforcement 443 and its bead-shaped edge 448 substantially reduce the tendency for cracks to propagate outwards towards the outer surface 446.

Fig. 24 illustrates a joint 450 which has several similarities to the device 440 in fig. 23. The joint 450 in fig. 24 differs, however, from that shown in fig. 23 in that a fiber-shaped reinforcement 451 comprises a first strip 452 and a second strip 453 which extends from the outer surface 454 inwardly through a slot 455 made with a similar profile to the slot 402 in fig. 20. The reinforcement elements 452 and 453 in the pear-shaped extension 456 of the slot are bonded to opposite internal surfaces of the cavity 456 and form an effective resistance to the propagation of cracks on the reinforced surface. Fig. 25 schematically illustrates how one prefabricated jacket 460 can be firmly connected to insulation 461 which is wound spirally on a container 463" "A ring 464 is attached to the container 463 by means of rivets 465 or similar fastening elements. The ring 464 is further riveted to a flanged ring 466 formed with an approximately diametrically arranged flange 467 and a perpendicular flange 468. A combination of the rings 464 and 466 terminates the foam insulation produced at the point of application. the rings 466 and 470 of materials with low thermal conductivity, such as glass fiber reinforced plastic; for example polyesters and epoxy resins. The rings 466 and 470 are connected to each other by means of a band 472 which is preferably produced at the point of use by impregnating glass fibers with a suitable hardener such as epoxy resin.The joint is in turn covered with an annular layer of foam plastic olation, designated 474 which can preferably be produced in the same way as the foam plastic insulation 46l. Fig. 26 shows an alternative embodiment of heat insulation generally designated 480 for a container. The insulation layer ,480 comprises several turns of synthetic foam plastic material designated 48l, 48la and 48lb. Each of the windings 48l has an approximately rectangular, elongated cross-sectional profile and is made with a pair of longitudinal slots 482 and 483 which extend in the longitudinal direction of the insulating winding and extend from a surface 484 determined to lie in the vicinity of the surface to be insulated, to a location at the opposite or away face 485. The slits 482 and 483 are spaced up to a quarter of the total distance between the strips 48l and 48lb and extend generally parallel to the space between them. The strip 48l further contains several transverse slits 486 which are arranged at approximately right angles to the slits 482 and 483 and extend through the entire thickness or height of the strip 48l. Strip 48l is connected to strips 48la and 48lb, as previously described. Expediently, the surface 485 can be provided with a reinforcement in the form of threads or a cloth 487. The cloth 487 lies over the edges of the strip 48l and the surface of the strip 485' and extends between the strips 48l and 48la and likewise between 48l and 48lb in places 1 near surface 485 facing away from surface 484. Adjacent portions of the fabric are connected to each other without directly connecting the strips 48l, 48la, etc. to each other, thereby forming an additional slit between the strips. As a series of strips such that the strips 48l, 48la and 48lb are placed in place,

the reinforcing fabrics will strengthen the joint between adjacent strips and likewise the outer surface of these and form a form of termination of crack formation which is particularly strong at the joints between the strips or windings. An insulation layer 488 is arranged over the cloth 487. The insulation layer 488 can also more appropriately consist of synthetic foam plastic and be attached to the cloth. A protective, optionally metallic layer 489 is arranged on the insulating layer 488 on the side facing away from the surface 485. Both layers 488 and 489 are placed in place at the same time as the strip 48l and welded or otherwise connected with previously assembled material.

The embodiment of the invention illustrated in fig. 26, is particularly appropriate when extreme temperature variations have to be taken into account between the inside of the insulation facing a tank, and the outward facing surface such as e.g. the protective layer 489. By the arrangement of slits such as the slits 482, 483 and 486 and similar slits in the other windings, the formation of cracks in the insulation as a result of contraction during cooling is prevented in a predetermined manner, and is at least limited to areas other than the joints between successive turns of the insulation.

In fig. 26, for the sake of clarity, the slits are shown with a finite width or thickness, but it is appropriate when manufacturing the insulation to make the slits very thin. It is well known that synthetic foam plastic can be sawn or cut with smooth cutting surfaces. Although the slot pattern in the drawing is shown square, other patterns can be used when desired.

An alternative embodiment of the insulation according to the invention is schematically illustrated in fig. 27 and is generally designated 490. The insulation 490 is generally made similar to that shown in fig. 26 and comprises several insulation strips 491, 491a and 491b which are glued together. The strip 491 is made with two slits 492 and 493 which extend in the longitudinal direction of the strip and correspond to the slits 482 and 483 in fig. 26. The strip 491 has a first surface 494 and a second surface 495. The slits extend from the surface 494 to a location near the surface 495. The surface 494 and corresponding surfaces on the strips 491a and 491b are provided with a reinforcing cloth 496. The cloth 496 can , if desired, be cut at locations corresponding to the connection between the slits 492 and 493 in the surface 494. A reinforcing fabric 497 similar to the fabric 487 is arranged on the surface 495 facing away from the surface 494. The fabric 497 suitably overlaps the strip 491b and extends into the joint between strips 491 and 491a, as previously described. Above the cloth 497 and similar cloths, an insulation layer 498 is arranged, e.g. in the form of a sheet of polystyrene foam provided with a protective layer 499 on the surface facing away from the surface 495.

In the joints between the successive strips 491, 491a and 491b, reinforcing tape 501 is arranged. The tapes 501 are preferably applied to the insulation strips before they are placed in place,

and preferably the reinforcing tapes at a location generally corresponding to the supply station 78 for the insulation strip comprise a plurality of elongated filaments embedded in a base mass of synthetic thermoplastic material which is heat-sealed or otherwise connected to the underside of the insulation strip before it is fed to the application head. If the insulation strip e.g. is a strip 491 of polystyrene foam, the reinforcing tapes 501 may contain filaments of, for example, metal or glass that are previously coated with polystyrene and heat-welded to the underside of the insulation strip to form a reinforcement both during the advance of the strip to the application head and in the finished insulation. The embodiment illustrated in fig. 27, ensures controlled cracking in the equatorial plane and limits cracking in a meridional direction by means of the reinforcing fabric 496.

When using the present invention, a curved or double-curved surface can be simply fitted with thermal insulation. Such insulation e.g. consisting of foam plastic can be arranged directly in contact with the container wall or alternatively can be arranged at a distance from this with or without a loose fiber mat as an intermediate layer. If it is desired to use heat-setting foam instead of thermoplastic foam, a suitable adhesive such as e.g. epoxy resin for assembling the insulations into a coherent body. The insulation can be provided with a skin; i.e. a reinforcement in the form of a textile cloth on the inward-facing and/or outward-facing surface. In a similar way, such a cloth can be arranged in the joint between successive windings of insulating material with or without previously formed slits or parts with low adhesion to regulate crack formation. Suitable reinforcing elements can be arranged in any desired locations and fixed by welding or by means of adhesive or by embedding in a foam-shaped, hardenable mass. In this way, the insulation layer can be given practically any desired properties.

If desired, cylindrical containers can easily be insulated in accordance with the present invention by using a suitable arrangement of guide rails; e.g. a guide rail at the top of the container and one at the bottom of the container with a suitable rectilinear support carried by the rails. To simplify the illustrations, control devices and control circuits have been omitted. For most applications, simple limit switches can be used to maintain the desired position of the foam application head or devices for applying a vapor barrier.

In certain cases, e.g. when prefabricated foam strips are used, it may be desirable to modify the welding apparatus illustrated in fig. 8 so that a vertical movement of a welding plate is obtained, e.g. the weld plate 215, to form a joint with the general configuration of. the joint in fig. 19 which can ensure greater flexibility as the diameter of the windings decreases, as well as a 3-penning relief space which extends generally vertically in the joint.

Depending on the particular requirements placed on the insulation of a container in each specific case, the Insulation can be applied in a direction from the bottom up or from the top down or in any other or desired way with practically any desired form of foam insulation with or without reinforcement and means for stress relief.

Claims (7)

1. Insulated cryogenic container comprising at least one first actual container with an outer doubly curved surface, a thermal insulation layer of rigid foam placed on the outer. surface where it covers at least a significant part of it, characterized in that the insulation is in the form of a number of largely parallel closed windings (83) which are connected to each other along their edges so that they continuously enclose at least part of the double-curved outer surface (44) of the container (41) in a heat-insulating sleeve, and that a vapor barrier material in the form of a spirally wound metal strip (261) is arranged on the surface of the foam plastic windings, the edges of the metal strip on the opposite windings being mechanically attached to each other. 2.. Method for producing an insulated cryogenic container as stated in claim 1, characterized in that a continuous strip of rigid foam plastic is wound on the container's doubly curved surface by means of at least one application head which can be moved in a spiral path around the container's circumference, during simultaneous welding of the opposite windings, the application head being moved during the application operation along an arc-shaped support frame which is simultaneously rotated around the circumference of the container. 3. Apparatus for manufacturing an insulated cryogenic container as stated in claim 1, characterized in that it comprises at least one arc-shaped support frame (61, 87) which extends over at least part of the circumference of the container (41) to be insulated, and is arranged to be rotated around this, a drive device (65, 91) for rotation of the support frame, as well as an insulation application device (82, 93) which is stored on the support frame (61, 87) and arranged to be moved along this under the support frame's rotation, thereby passing through a spiral path over at least a part of the container (41) to be insulated. 4. Apparatus as stated in claim 3, characterized in that the arc-shaped support frame near one end (62, 88) is pivotally supported in a fixed point (71) located in the extension of an axis of symmetry through the container, and that the drive device (65, 91 ) is attached to the support frame (61, 87) at a point on it at a distance from the fixed pivot point (71), to cooperate with a circular guide rail (57, 95) running around the circumference of the container, for rotation of the support frame around the container. 5. Apparatus as set forth in claim 3 or 4 where the insulation application device (82, 93) is designed for applying foam plastic, characterized in that it comprises a heat sealer (150) which is carried by the insulation application device and is designed for welding consecutive windings together of the insulation material. 6. Apparatus as stated in claims 3-5, characterized in that it comprises a device (84) for applying a continuous strip (261) of a vapor barrier material over the insulation applied by means of the insulation application device (82, 93), the device ( 84) for applying the vapor barrier strip is arranged at a fixed distance from the device for applying the insulation. 7. Apparatus as stated in claim 6, characterized in that it comprises a heat sealer (279) for welding the vapor barrier material to the insulation material.