SU897120A3 - Tank for low-temperature liquids - Google Patents

Description

(54) TANK FOR LOW-TEMPERATURE The invention relates to a cryogenic technique, in particular to the design of large rheogenic tanks, for liquefied natural gas. Tanks are known that include thermal insulation from foamed materials, which is supported by elements, such as bolts, attached to a liquid-tight tank wall til. The disadvantage of such tanks is the low strength of their heat insulation. The closest in technical essence and the achieved effect to the proposed is a reservoir containing outer and inner shells, thermal insulation placed between them, made in the form of layers of foam material and wire meshes, installed equidistant to the inner shell of the reservoir, and a layer impermeable to ti and placed between the internal liquid fluids tank shell and thermal insulation 2. However, in this tank, thermal insulation also has insufficient strength and can crack when cooled to cryogenic temperatures. The purpose of the invention is to increase the thermal insulation strength and prevent its cracking. The goal is achieved by the fact that the reservoir additionally holds layers of fibrous material placed between the layers of foam material, wire meshes are installed between the layers of fibrous and foam materials in the plane of their contact, and the spacing between the grids and the dimensions of their cells are reduced; in the side of the inner shell of the reservoir reins Figure 1 shows a reservoir- designed for low-temperature liquids, a partial section; 2 shows the placement of bolts for fastening the insulation on the inner surface of the tank wall; FIG. 3 is a vertical sectional view of one of the support bolts; in fig. - heat insulating jacket with layers of fibrous material, partial section; in fig. 5, the node I of FIG. L is showing the construction of the insulation.

The tank contains a wall 1, which can be of any shape. The sheet of metal forming the reservoir is, for example, a steel sheet used usually as a structural material in the construction of ships. One of the metal anchors 2, designed as saddles for support bolts, is shown by spot welded in zone 3 to the inner surface of the tank wall 1.

The anchor 2 is screwed into the lower end of the hollow support bolt k, which is filled inside with polyurethane foam or other heat insulating material 5. The strings 6 and 7 of fiberglass or stainless steel wire are supported and tightened by bolts in the form of multiple layers forming a grid that is equidistant to the inner wall surface reservoir. The strings 6 and 7 are arranged so that the closer they get to the low-temperature side, the greater the density of their mutual placement.

A screw 8 is attached to the head of the support bolt k a plywood sheet 9. The latter is made with holes and provided with plugs 10, polyurethane foam is injected through the holes into the space between sheet 9 and wall 1, so that a heat insulating layer 11 of rigid polyurethane foam is obtained. The holes are then closed with plugs 10. The surface of sheet 9 is coated with a multilayer coating 12 formed of several layers of fiberglass and epoxy resin or polyurethane resin alternately lying on top of each other to prevent contact of cryogenic liquid with the seams of sheet 9When using rigid polyurethane as a heat insulating material tendencies to increase the tensions on the low-temperature side, whereas with increasing temperature the stresses decrease and some April voltage compression temperature-side. In a number of cases, thermal tensile stresses will be strong enough to cause cracking of the insulating layer.

Thermal insulation is designed to prevent the insulating layer from cracking under the influence of thermal stresses by means of grids of strings 6 and 7 with a lower coefficient of linear elongation than the coefficient of linear elongation of the insulating material.

In addition, the vertical gaps between the walls are made smaller on the low-temperature side for additional voltage of the heat insulating layer 11.

The proposed construction of an insulating layer offers particular advantages for large tanks, for example, with an area of this part 30 x 30 and a height of more than 20 m, which is completely insulated. At the corners of such a huge reservoir, the thermal stresses can increase to significant values. Since the support bolts C themselves are good insulators, metal meshes stretched between them will cause heat transfer in the direction equidistant to the steel sheet of the tank. In the transverse direction, heat transfer takes place only through the insulating layer 11 and through the supporting bolts 4. Tensioning the metal grids with bolts k is advantageous in that the grids help to equalize the temperature distribution per unit thickness of the insulating layer 11 and make the same voltage in the layer when exposed to temperature a layer of liquid 13.

It is desirable that the arrangement of the support bolts 4 be carried out (FIG. 2) so that the gaps between the fiberglass strings or the metal wires 6 and 7 can vary widely.

Hooks k can be provided on the support bolts k (Fig. 3) for strings or wires.

Claims (2)

It is known that polyurethane foam, applied by spraying or in any other way, can serve well as thermal insulation at temperatures down to -100. Therefore, it is generally economical and efficient construction can be obtained by creating insulation for temperatures of this level in the usual way, followed by creating insulation for lower temperatures according to this description. Also provided is thermal insulation with a secondary liquid-impermeable wall parallel to the inner surface of the tank and located at a distance from it, with an insulating structure being created inwardly from the secondary wall. Secondary, liquid-tight, wall 15 rests on bolts k. In the gap between the wall 15 and the inner hull of the vessel 1, a solution of the thermally insulating material 16 is injected. The secondary wall 15 and the insulating material 16 can be pre-formed as a factory-made panel and the panels can be assembled in place. The expandable hard urethane solution is sprayed and foamed on the inner surface of the secondary, liquid impermeable, wall 15, thus forming heat insulating layers and so on. The short staple glass fiber 21 is loosened and scattered across the foamed insulating layers 18 and 20 The intersecting wires 22 and 23 are drawn into a mesh over the fiberglass layer 21 and the next insulating layer is applied by spraying, causing the meshes to be dipped into the insulating layer. Thus, the insulation layers and wires are alternated several times to obtain a multi-layer coating with a desired wall thickness. In order to form the innermost layer, a foaming agent 2D containing short staple glass fiber is sprayed over the insulating layer, and the resulting mixed layer is then coated with a liquid-impermeable wall 25 made of fiberglass and synthetic resin, for example a polyurethane resin. When making such an insulation at the time of applying a layer of polyurethane, short staple glass fibers show a tendency to ascend, but are retained from this by nets. . The wire mesh layers 22 and 23 can be formed by a method according to the "official" layer in Figure 5. The surface of the foaming layer is electrostatically charged, so that the short staple glass fibers rise and form an elastic layer, the grids are temporarily fixed above this layer by spraying an expanding insulating material, as shown at point 2b. Then the next insulating layer of polyurethane is applied. Due to the features described above, the present invention allows the use of conventional steel sheets for the wall 1 of the tank, thereby providing a significant cost advantage. In addition, the gaps between fiberglass strings or metal wires forming grids parallel to the tank wall can be gradually reduced, providing an effective and sufficient reinforcement of the insulating layer in order to solve the problem of thermal stresses. If wires and short staple glass fibers are used in combination to form the wire layers, the resulting mesh structures can have large cells, since the glass fibers fill the cells and provide reinforcement with desirable strength. For example, a network of wire, which should have a cell size of about 5 mm, may contain much larger cells with a size of 20 mm if the wire is supplemented with fiberglass. An additional advantage associated with the use of metal wires as a grid material is that the temperature distribution in the horizontal direction of the insulating coating is uniform, and the occurrence of any local thermal stresses in the coating can be prevented. Claims A tank for low-temperature liquids containing outer and inner shells, heat insulation placed between them, made both wire grids installed equidistantly to the inner shell of the tank, and a layer impermeable to liquid, placed between the inner shell of the tank and heat insulation, In order to increase the strength of the thermal insulation and prevent its cracking, the tank additionally contains layers of fibrous material placed between nennogo material provo3, W 1/3 ,12 / jL V / if / X ZtiCn-V g .,.  Vjry - ;; .-- iv: fy.; AVj j; : yy. ... -. / ...; ::.;.:,; i-v. . f: Sv --y "sI-J-.A: W" .L-b -4VH i  u fi i. Ш7  ; i; ; jgvi; ; i::;  : Vj V..; -4 ..- :: iy-y i . .t u-.i.-r.-V. ST.-1TA. fibrous and foamed materials in the plane of their contact, and the spacing between the grids and the dimensions of their cells are reduced towards the inner shell of the tank. Sources of information taken into account in the examination 1.Patent of France No. 2109153, cl. F 16 L 59/00, 05.25.72: 2. The patent of Germany No. 1289071, cl. 17 9, 02.11 .69. jj -....; V-- -, - ..;. zg iy / vrj- / ::::; c ;; /.-.Y ry / i; 77 FIG. E1. © ® ® @ © Phage.2 .. Schschschsch D§ §Sh sh% w:; c;) .x M S jvji. 2 :: Jm- --- i.iff: ff -: - i - i: - i: lii; / j ( ..chI-i iP.IiiOiSjix. vt-j- / tjii -illj. iSTii ... StfV Vt.N ",. V. J C / NT-r. ... i (.i 4Q 27   . --- -XJ c -o i el - ::.; ---- V -:; - :: v -V rai g Jgfeiiij j   {i- -v d {5y; yb 4 :: v; :, ti.rvfv :: 25 / 8 Fi.g.5 2f 23