AU595445B2 - Temperature controlled tank container - Google Patents

Description

C 0M MO0?NWE A L T O0F AU STR A L IA PATENT ACT 1952 COMPLETE SPECIFICATION

C(ORIGINAL)

FOR OFFICE USE CLASS INT. CLASS_ 4 4 3~q 9 9 9 '944 4 4 4 4 9.

4. 4 4 44 9 *4 4 ~9 4 44 4 4 4 4 L. 4 44 4. 4 C. 4 Application Num~ber: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art-: I U. WV .t ~1 NAME OF APPLICANT: WESTERWAELDER EISENWJERK GERH-ARD G11IBH ,ADDRESS OF APPLICANT:- Ringstrasse D-5241 Weitefeld, Federal Republic of Germany.

NAME(S) OF INVENTOR(S) Hielmut GERHIARD ADDRESS FOR SERVICE.* 'DAVIES COLI 4 ISON, Patent Attorneys I Little Collins Street, Melbourne, 3000.

COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED:.

"TEMPERATURE CONTROLLED TANK CONTAINER" The following statement is a full description of this invention, including the best method of performing it known to us 9~iUli~i -iti-lli- i. ill- 2 Specification A temperature-controlled tank container is known from DE-A-2,917,364, which has a tank mounted between two frame end structures and composed of a cylindrical shell and two end bottoms. The tank surface is surrounded on all sides by an insulating jacket, on one end face of which two port-holes for .,iO introducing and discharging a temperature control medium are disposed one above the other. Division webs are provided between the tank surface and the insulating jacket for causing a forced flow of the temperature control medium along the tank 4, •9 surface.

It is emphasized in the above document that the insulating jacket is disposed on the planar wall surfaces of a parallelepiped-shaped container frame. Between these planar wall surfaces and the cylindrical container, there exist large 9.Q triangular flow cross-sections so that a large portion of the 20 temperature control medium is permitted to flow without contacting the container surface, all the more as through-holes for the medium, that are formed in supporting walls disposed transversally to the longitudinal tank axis, are provided at a relatively large distance from the container surface.

Moreover, the space between the container surface and the insulating jacket of the known tank container is partitioned by division webs in such a way that the temperature control medium flows substantially axially of the tank, so that a laminar flow may occur over large distances. Depending on the arrangement of the division webs, a flow path is formed which amounts to no more two to four times the tank length. For these reasons, the extent to which the temperature control medium, that may serve either for cooling or heating the tank, can be utilized is restricted. In addition, the disposition of a the insulating jacket on the planar surfaces of the container frame requires considerable expense in terms of insulating and covering material and is accompanied by a considerable increase in the tare weight of the overall tank container.

:r 1 m r 1 4 Finally, the known tank container requires a box-like container framework; lacking this, the known design is unsuited.

DE-A-2,917,364 referred to above briefly mentiones an alternative design in which helical division webs are provided to partition the space between outer and inner shells to form flow channels for a temperature control medium. The document does not disclose, however, any details of the arrangement required to achieve a forced flow of the temperature control S.r medium along a closed path from the inlet port-hole to the 0 outlet port-hole.

Temperature-controlled tanks are required particularly S.for shipping food. Such tanks are usually made of special steel and are formed with walls that are as thin as possible S for economical reasons. Conventional tank containers of this type therefore require reinforcing rings welded to the outer tank surface to obtain the required strength of the tank body.

It is an object of the invention to devise a temperature- 0S *controlled tank container which does not require a complete container framework, which while having a simple structure I.I*0 and minimum tare weight permits uniform contact of the tank surface by the temperature control medium flowing around it with good utilization of the temperature difference, and which S* has sufficient strength even at reduced thickness of the tank shell material.

To meet this object, an even number of division webs are substantially equi-angularly distributed round the tank circumference and form a continuous circulation channel from the input port-hole to the outlet port-hole. At the same time, the division webs are formed as section bars to reinforce the tank shell and thus replace the otherwise required reinforcing rings.

The temperature control medium is passed as a layer of uniform thickness of only a few centimeters in practice along a helical path about the cylinder circumference in intimate 36 contact with the tank surface, and that at least once in either direction. The uniform and small spacing of the insulating jacket from the tank shell co-operates with the helical shape of the flow path to achieve a continuous rotation of the S/ 4 1 temperature control medium, so that the entire flow volume is utilized for extensive heat exchange on the tank surface.

Due to the fact that the tank is closely enveloped, a comparatively small amount of insulating and covering material is required for the insulating jacket, and the tare weight of the tank container is minimized. The helically extending division webs are easily mounted, and they result in a more stable support for the insulating jacket than the conventional rings which extend circumferentially, because the former provide load transfer points at locations which change continual- 9 ly in the axial direction.

,In contrast to the prior-art tank container referred to 0 above, the invention does not require a closed box-like container framework. Rather, the structure of the present inven- 15 tion is suited for tank containers in which the frame is reduced to just two end structures which are joined to the 9 bottoms of a self-contained tank.

It is known from DE-U-1,851,590 for a double walled storage tank to use helically disposed wires so as to keep por- .'20 tions of an outer shell in spaced relationship from an inner shell. Apart from the fact that the outer and inner shells of the known tank are only partially spaced from each other, the wires used therein are neither intended nor suited to form continuous and mutually spaced passageways for the flow of a temperature control medium. In addition to this difference, the division webs of the present invention, by virtue of being formed as section bars, increase the compressive strength of the cylindrical tank shell similar to conventional circular reinforcing rings.

Another tank is known from US-A-3,335,904, wherein a filler material of relatively low structural strength and a helical reinforcing rib are disposed between an inner skin and an outer skin of the tank shell. This known container, however, is made of glass fibre reinforced plastics, the space between the outer and inner skins of the tank shell is completely filled, and the reinforcing rib does not serve to provide channels Zor flowing a temperature control medium.

Similarly, US-A-4,548,335 discloses a liquid gas con- -1 5 tainer/(w gas the space between an outer vessel and an inner vessel is filled with insulating material. A tube which is helically disposed within the insulating material serves to discharge liquid gas and is arranged immediately adjacent the outer vessel to increase the heat transfer for conversion of the liquid to the vapour phase. Again, the helical structure does not serve to partition the space between the outer and inner vessels to form flow channels for a temperature control medium.

10 Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which Fig. 1 is a schematic side view of a temperature-controlled tank container, Fig. 2 is an end view of the tank container, wherein the left half of Fig. 2 is an end view of the tank container of Fig. 1 as viewed form the left and the right half is an end view of as viewed from the right, 20 Fig. 3A and 3B are schematic illustrations of the two end faces of a different embodiment of the tank container.

As shown in Figs. 1 and 2 the tank surface is composed of a cylindrical shell 10 and bottoms 11, 12 attached at either end thereof, said bottoms being respectively joined via end rings 13 with diagonal braces 14 of frame end structures Such a purely endwise suspension of a cylindrical tank from two end structures 15 is known from DE-C-3,212,696. In Fig. 1, the end structures 15 are shown to be additionally intercon- 30 nected by lower longitudinal rails 16. The right-hand tank bottom 12 as viewed in Fig. 1 is provided with a manhole 17 and a discharge fitting 18. Also, a filling connection 19 is illustrated near the left-hand (as viewed in Fig. 1) tank bottom 11 in the vertex line of the cylindrical tank shell Two division webs 20, 21 extending along two helices offset by 1C0 0 are placed about the cylindrical shell 10 of the tank surface. It is assumed in Fig. 1 that each division web 21 surrounds the tank surface twice, all four corner 1 1 6 0* 5 *5* 9*

.J

5* S i *r 9 points of said division webs being disposed in the illustration of Fig. 1 in a horizontal plane including the tank axis. The two division webs 20, 21 may be rectangular-section strips of, for instance, 8 mm x 30 mm which have their narrow edge welded to the tank surface. They thus fulfil the function of reinforcing ring normally provided on cylindrical tanks. In order to avoid peak stresses at the end points of the division webs 20, 21, the webs extend from pipe sections 22 each welded to the tank surface with a closed circular seam.

10 The division webs 20, 21 keep an insulating jacket generally referenced 23 in spaced relationship from the tank surface. As indicated in the partially sectional view at the bottom of Fig. 1, the insulating jacket 23 is composed of an inner skin 24, an outer skin 25 and an insulating material 26 sandwiched therebetween. In areas between the division webs 21 the inner skin 24 of the insulating jacket 23 may be supported on the tank surface by additional spacer members in the form of bead- or socket-like shaped portions 27.

Preferably, the insulating material 26 is formed largesized foamed polyurethane slabs which are pre-slotted on their surfaces facing the inner skin 24 so that they can be given the required cylindrical shape.

The insulating jacket 23 extends with the cylindrical shape defined by the division webs 20, 21 along the entire length of the tank container right to the end structures 15 to terminate on flat or curved insulating plates 28 which are inserted in said end structures 15 and may have a design similar to the insulating jacket 23. Thus the tank is insulated on all sides.

As will be apparent from the left-hand part of the end view of Fig. 2, the left-hand (as viewed in Fig. 1) bottom 11 of the tank is provided with the two openings 31, 32 for connection to a supply system for the temperature control medium.

Such supply systems are common especially in container ships where the temperature control medium is especially cooling air which is available in large flow volumes at small pressure differences. Similar supply systems are also provided in container yards in ports.

1 "1 I~u C--Y.L 7 In such a cooling system the openings 31, 32 of the tank container are also called "port-holes", the lower opening 31 forming an inlet port-hole and the upper opening 32 forming an outlet port-hole. The flow of cooling medium is caused by an overpressure existing at the inlet port-hole 31 and a corresponding negative pressure existing at the outlet port-hole 32.

As will be further apparent from Figs. 1 and 2, the space enclosed between the left-hand tank bottom 11, the insulating 1 jacket 23 and the end structure 15, which terminates in an in- 10 sulating plate 28, is divided both inside and outside of the 9oooo* S end ring 13 by means of a division plate 33 extending in the S. horizontal centre plane. The division plate 33 starts from the two pipe sections 22 where the division webs 20, 21 terminate •o on the two opposite sides of the tank surface. The end ring 13 is provided with through-holes 34 both above and beneath the division plate 33. Corresponding through-holes may alternatively or additionally be provided in the flanges of the diagonal braces 14, which flanges extend in the longitudinal direction of the tank. A further possible modification resides 20 in passing the cooling medium about the diagonal braces 14 provided a sufficient distance is maintained between said braces and the insulating plate 28 as well as betweem the braces .and the insulating jacket 23.

In this way a flow passageway for the temperature control medium is defined which extends from the lower inlet port-hole 31 through the lower through-holes 34 in the end ring 13, one of the two helical flow passageways defined between the two division webs 20, 21 to the area of the right-hand tank bottom 12 (as viewed in Fig. thence back through the other of the two helical flow passageways and through the upper throughholes 34 in the end ring 13 to the outlet port-hole 32. Since the flow passageways between the two division webs 20, 21 have a relatively small uniform height, the temperature control medium flows around the entire tank surface in intimate contact contact therewith, The helical design of the flow passageways simultaneously causes continuous rotation of the temperature control medium whereby the generation of a laminar flow, which wduld be detrimental to heat transfer, is prevented.

.I i 8 As will be apparent from Fig. 1 and 2, the end ring 13 which joins the right-hand tank bottom 12 to the end structure is continuous and is interrupted only in the vicinity of the discharge fitting 18. The diagonal braces 14, which connect this end ring 13 to the end structure 15, also are formed with small through-holes. On the other hand, the two division webs 20, 21 end at a distance from the end ring 13 so that there is room for the passage of the temperature control medium. In this embodiment the temperature control medium does 10 not flow across the portion of the tank bottom 12 disposed ooo S" inwardly of the end ring 13. Normally, temperature control of e*.

the inner portions of the tank bottoms 11, 12 need not be proa: a vided in view of the extensive flow of medium especially a e around the entire cylindrical shell 10. If, however, temperature control for this portion is required, the division webs 21 will be extended to the right-hand end ring 13, and the r latter of the corresponding diagonal braces 14 will be provi- Sg. ded with through-holes 34 similar to those indicated in the left-hand part of Fig. 1.

S q. 20 Whereas the embodiment illustrated in Fig. 1 is provided with only two helical division webs 20, 21 offset by 1800, it is basically possible to provide four or a larger even number of division webs which result in a correspondingly increased number of helical flow passageways so that the entire flow path for the temperature control medium along the tank surface is extended.

Fig. 3A schematically shows the end face of a tank container provided with the inlet and outlet port-holes 31, 32, said tank container being provided with four helically dis- I 30 posed division webs 35, 36, 37, 38. Fig. 3B shows the opposite end face of the same tank container. Along the end face illustrated in Fig. 3A the division webs 35 to 38 extend right to the end ring 13. Also, each of the two port-holes 31, 32 opens into a communicating passageway 40 defined by two limiting webs 39 extending at an acute angle, said communicating passageway 40 being in connection communicated via through-holes in the end ring 13 with the respective flow passageway defined between a pair of division webs 35, 36 and 37, 38, re- I rA -9spectively. Outside the communicating passageways 40 the end ring 13 is provided with further through-holes which communicate the flow passageway defined between the division webs 36, 37 across the hemispherical portion of the bottom to the opposite flow passageway defined between the division webs 35, 38.

At the other end face shown in Fig. 3B, the division webs 37 extend right to the end ring 13 provided therein, while the other two division webs 36, 38 terminate in spaced relation- 1 ship therefrom. With this embodiment the temperature control 0 10 medium flows from the intlet port-hole 31 along the path indigoo,*: 1 cated by the arrows A, B, C, D and E towards the outlet porthole 32, said path winding four times helically around the tank.

1

Claims (8)

1. A temperature-controlled tank container comprising a tank formed of a cylindrical shell and a pair of end bottoms and mounted between a pair of end structures, an insulating jacket which surrounds the tank surface on all sides, two port-holes for introducing and discharging a o temperature control medium being formed above one another in e S:one end face of the insulating jacket, and fo 0 Sso division webs disposed between the tank and the insulat- *0 S ing jacket and helically surrouding the tank shell, an even number of said division webs being equi-angularly distributed a about the tank circumference to form a continuous flow channel S.. *for the temperature control medium from the inlet port-hole to S.. the outlet port-hole, said division webs being formed of sec- tion bars reinforcing the tank.

2. The tank container of claim i, wherein the tank is con- nected to said end structurcsby means of end rings mounted on said bottoms, at least some of said division webs terminating at the end face remote from said port-holes at a distance from the respective end ring.

3. The tank container of claim 2, wherein at least some of said division webs are attached to the end face provided with said inlet and outlet port-holes, and wherein flow passageways defined between two respective division webs communicate with said port-holes via through-holes formed in the respective end ring and via communicating passageways defined by limiting I 1 1~ A 11 webs on the respective tank bottom.

4. The tank container of claim 3, wherein said limiting webs, which extend from each port-hole to the end ring, di- verge at an acute angle.

The tank container of claim 1, wherein said insulating S, jacket comprises an inner skin, an outer skin and an insulat- ing material sandwiched therebetween.

6. The tank container of claim 5, wherein said inner skin is provided with shaped portions for additional supporting said insulating jacket relative to the tank surface.

7. The tank container of claim 5, wherein said insulating material is applied in the form of foamed slabs which are pre- slotted on their surface facing said inner skin.

8. A temperature-controlled tank container substantially as Shereinbefore described with reference to the drawings. Dated this 3rd day of May 1988 WESTERWAELDER EISENWERK GERHARD GMBH By its Patent Attorneys DAVIES COLLISON .I .c L4r~l. 1 C _~r -I