RU2363636C1 - Stationary roof of vertical double-walled steel tank - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention refers to oil industry and can be implemented for tank batteries of oil and oil product pipelines, at petroleum storage depots, and at sea and river oil terminals. The stationary roof consists of bearing elements, of a cover, of a reinforcing ring, of a central shield and of a breather; the bearing elements are made in form of diametrically pair wise double-beam steel semi arches bent along radius equipped with cross rigid constraints eccentrically arranged relative to lengthwise axes of the semi arches; guy rods pass through the rigid constraints; also each double beam steel semi arch with its internal end is loosened with a hinge assembled on the central shield equipped with the breather; in span each semi arch freely rests on a main wall forming a structure of a pylon type; with external end the semi arch is loosened with a hinge arranged on the reinforcement ring of the tank in upper part of a protective wall.

EFFECT: facilitating overhead cover of significant (more, than 50…60 m) spans of working area in vertical double walled steel tanks of big capacity, which allows implementing tanks of said type in climatic regions with considerable snow cover; also invention decreases load on main wall to great degree (fabricating structure from normal steel is possible), and protects main wall from environment corrosion.

2 cl, 5 dwg

Description

The invention relates to the oil industry and can be used in tank farms of trunk oil and oil product pipelines, at oil depots, at sea and river oil terminals.

Known designs of steel vertical tanks intended for the storage of oil and oil products with a capacity of 40 ... 50 thousand m ³ or more, equipped with a floating roof [1].

One of the structures of the floating roof consists of upper and lower decks, the space between which is divided by radial and transverse partitions, creating airtight compartments and forming a continuous pontoon over the entire roof area. To prevent the rotation of the floating roof around its axis, guides in the form of pipes are provided. The annular space between the floating roof and the tank wall is sealed with a sealing shutter.

The disadvantages of the roof structures of this type of reservoirs are the unreliability of their work in climatic regions with large snow cover, the complexity of installation and operation. The unevenness of the snow cover of the floating roof leads to distortions and, as a consequence, to flooding.

Known designs of steel vertical tanks for storing oil and oil products with a capacity of 30 ... 50 thousand m ³ equipped with a stationary spherical roof made of light alloys [2].

The dome of a spherical shape is a structure consisting of a frame and flooring. The core mesh of the supporting frame is designed according to the star pattern. The supports are pivotally mounted on the steel ring of the tank stiffness, which is also the lower spacer ring of the dome. All elements of the dome frame are rectilinear rods of extruded I-beams. The elementary geometric shape of the frame is a triangle. The flooring also consists of separate triangles. The connection of the individual elements of the frame, as well as the flooring with the frame is carried out using bolt and screw connections.

Among the disadvantages of roofs of this type of tanks is the use of truss structures made of light alloys to cover large spans of the working space (more than 60 m), which significantly complicates and increases the cost of roof construction, its assembly, installation of cover and operation, and also requires the use of measures to neutralize differences of electrode potentials of the materials of the tank wall (steel) and the roof (aluminum alloy).

The closest in technical essence to the proposed design is the construction of a stationary roof of vertical steel tanks of the type "glass in a glass" with a capacity of 40 thousand m ³ or more, made by analogy with a spherical shield steel roof on a vertical steel tank with a pontoon with a building value of 20,000 cubic meters [ 3]. The spherical shield roof is represented by load-bearing elements - beams in the form of I-beams, going from the central ring to the stiffening ring installed around the perimeter of the wall in its upper part, by transverse ties in the form of corners and a flooring in the form of sheets.

The overlapping of a vertical two-walled steel tank is either floating (a floating roof installed in a space bounded by the main wall) or stationary - similar to the spherical shield steel roof discussed above. The disadvantage of the construction of the stationary roof of a vertical two-walled steel tank is that the span between the main and protective walls (with the help of an atmospheric visor) and the overlap of the working space (with the help of a stationary roof) are separated. Such a constructive solution is imperfect, as it complicates the installation and operation of the tank and does not solve the problem of overlapping large spans in the workspace.

The technical result of the invention is the ability to overlap significant (more than 50 ... 60 m) spans of the working space in vertical double-walled steel tanks of large capacity. The proposed technical solution allows you to unload the upper part of the semi-arches from bending moment caused by constant and temporary loads applied to the roof (dead weight of the semi-arches, weight of the coating and snow cover, wind), increase the length of the semi-arches, which allows you to overlap the space between the main and protective walls, and also unload the main wall from the spacer forces arising in the semi-arches, and transfer these forces to the stiffening ring installed in the upper part of the protective wall.

The technical result is achieved by the fact that the stationary roof of a vertical two-walled steel tank contains load-bearing elements, a cover, a stiffening ring, a central shield and a breathing tube, and the load-bearing elements are made in the form of bent radially and diametrically pairwise two-beam steel half-arches with transverse eccentrically mounted relative to the longitudinal axes of the half-arches rigid ties along which cable ties are passed, with each double-girder steel semi-arch hinged at the inner end rum mounted on a central shield, equipped with a breathing pipe, in the span, each half-arch freely rests on the main wall, forming a pylon type structure, and the outer end of the half-arch is hinged, mounted on the reservoir stiffness ring in the upper part of the protective wall (see figure 1) .

Comparative analysis shows that the claimed stationary roof differs from the prototype in that its load-bearing elements are made in the form of diametrically pairwise two-girder steel half arches, unfastened by hinges mounted on the periphery of the tank on the stiffening ring of the protective wall and freely resting in the span on the main wall with the formation of the pylon structure type; the inner ends of the semi-arches are based on hinges that are mounted on the central shield, while the half-arches themselves are made of two-beam with transverse rigid ties eccentrically mounted relative to their longitudinal axes, along which cable ties are skipped, and the step of installing transverse rigid ties is determined by the condition of the passage of the tension vector of cable-stayed ties through the area bounded by the contour abcd of the cross section of the semi-arches (see figure 1).

The invention is illustrated by drawings, where figure 1 shows a schematic diagram of the layout of the elements of the roof of the tank and the vector of the tension force of cable-stayed couplers within the contour a-b-c-d of the cross section of the half-arch, and in figure 2 - General view and cross-section of the half-arch.

The design of the vertical two-walled steel tank includes a protective wall 1 and the main wall 2. In the upper part of the protective wall along the perimeter there is a stiffening ring 3. Bearing elements are represented by diametrically paired two-beam steel half-arches. Each two-frame steel semi-arch is made in the form of two beams 4 bent along the radius of curvature of the roof R, for example, of two channels or two I-beams, supported through a hinge 5, having one degree of freedom, on a stiffening ring and on a hinge 6, having two degrees of freedom and installed on the main wall. The inner end of the two-beam steel half-arch is connected to the central shield 7 by means of a hinge 8, having one degree of freedom and mounted on the central shield, equipped with a breathing pipe 9. Each two-beam steel half-arch is made with transverse rigid ties 10 eccentrically mounted relative to the longitudinal axis of symmetry of the beams, through which are passed cable ties 11, tensioned using hydraulic or screw jacks (not shown). On the beams of diametrically pairwise two-girder steel half-arches, a sheet covering 12 is laid covering the span between the protective and the main walls, as well as the working space of the tank limited by the main wall.

The proposed design works as follows. When exposed to constant and temporary loads on the tank roof, hinges 5 and 8 make it possible to move the roof in a vertical plane, and hinge 6 - in a horizontal one. The spacer forces T from the resultant load S (the vector of which is applied at the center of gravity of each two-beam steel half-arch and is directed vertically downwards) are transmitted to the protective wall and lie in the horizontal plane, and the forces stretching the upper part of each two-beam steel half-arch are compensated by the bending moment M by the preliminary tension of the cable-stayed screeds. The step of setting the transverse connections t is determined by the condition of the passage of the vector N of the tension force of the cable-stayed couplers through the area bounded by the contour a-b-c-d of the cross section of the double-beam steel half-arch (see figure 2).

The inventive stationary roof of a vertical double-walled steel tank reliably overlaps the working space of large-capacity tanks and, thus, allows the use of vertical double-walled steel tanks for operation in climatic regions with large snow cover, significantly reduces the load on the main wall, which allows for the manufacture of a stationary steel roof normal quality, and also protects the main wall from atmospheric corrosion. The environmental and fire safety issues are much simpler and more reliable, since the claimed roof, firstly, allows the use of well-known constructions of lightweight pontoons with a membrane made of practically fireproof materials (for example, foam glass), and secondly, as part of a double-walled tank - refuse boning. In addition, the evaporation of the product stored in the tank is reduced, since both the pontoon (floating cover) and the stationary roof (stationary cover) impede the release of product vapor into the environment.

Information sources

1. GG Vasiliev and others. Pipeline transportation of oil. Ed. S.M. Vainshtok. Textbook for universities in 2 volumes - M .: NedraBiznesentr LLC, 2002, t.1. - Page 320-321.

2. RD 16.00-60.30.00-KTN-025-1-04 book No. 1. Design standards for domed roofs and pontoons made of aluminum alloys for vertical steel and reinforced concrete tanks, the rules for their operation. - Page 5-9.

RD 16.00-60.30.00-KTN-025-1-04 book number 2. To design standards for domed roofs and pontoons made of aluminum alloys for vertical steel and reinforced concrete tanks, the rules for their operation. The application is graphical. Page 3.

3. TP. G.1.000.4.10302.005-05-PP-146. Typical design of a vertical steel tank with a pontoon made of aluminum alloys with a building value of 20,000 cubic meters. The calculations. Volume 4. Sheets 2, 3.

4. PB 03-605-03. Rules for the construction of vertical cylindrical steel tanks for oil and oil products. - Clause 3.10.

Claims (2)

1. A stationary roof of a vertical two-walled steel tank containing load-bearing elements, a cover, a stiffening ring, a central shield and a breathing tube, characterized in that the load-bearing elements are made in the form of bent radially and diametrically pairwise two-beam steel half-arches with transverse eccentrically mounted relative to the longitudinal axes of the semi-arches rigid ties along which cable ties are skipped, with each two-beam steel semi-arch with an inner end fixed by a hinge installed on the central shield, equipped with a breathing tube, in the span, each half-arch freely rests on the main wall, forming a pylon-type structure, and the outer end of the half-arch is secured by a hinge mounted on the reservoir stiffness ring in the upper part of the protective wall. 2. The stationary roof of a vertical double-walled steel tank according to claim 1, characterized in that the step of the transverse connections of each two-beam steel half-arrays is determined by the condition of the passage of the tension vector of cable-stayed couplers through the platform, limited by the contour of the cross-section of this two-beam steel half-arrays.

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