Method for thermally insulating reservoirs

Abstract

The invention is directed to a method of insulating tanks having a capacity between 200 m.sup.3 and 20,000 m.sup.3 used for storage of oil and oil products. In the method, foundation elements, including tank bottom heat insulation, are prepared. The tank is mounted on the prepared foundation, then insulation of the tank walls and roof is installed. Supporting relieving skirts are mounted on the tank walls and roof, forming tiers. The tiers are filled with foam glass blocks having expansion joints. A top coat of metal sheets is mounted on the outer surface of the blocks. Foam glass blocks in the lower tier are made to be removable to provide access to a wall-bottom corner weld joint, and the blocks of the remaining tiers are fixed to the tank surface and interconnected with an adhesive material.

Claims

1. A method for providing heat insulation of a tank, comprising: installing a wall, a roof, and a bottom on a foundation; coupling supporting relieving skirts to the tank, the supporting relieving skirts defining tiers; forming a heat-insulated layer by positioning foam glass blocks in the tiers including a lower row of foam glass blocks that include detachable foam glass blocks set on a lower tier of the relieving skirts wherein a shock absorbing sealing gasket, sized for a snug fit with adjacent blocks, is attached around a perimeter of each of the detachable foam blocks, while additional rows of foam glass blocks above the lower row of foam glass blocks are coupled to the tank via an adhesive wherein the blocks of adjacent rows are offset from one another; forming at least one vertical expansion joint and at least one horizontal expansion joint in the heat-insulated layer; coupling at least one corrugated metal sheet of galvanized steel having a thickness of 0.70.08 mm and an anticorrosive coating on the outside to an outer surface of the additional rows of foam glass blocks above the lower row of foam glass blocks; and fastening the at least one metal sheet to the supporting relieving skirts using screws with sealing gaskets.

2. The method of claim 1, wherein the supporting relieving skirts are mounted on the wall and the roof and separated by between 1.5 meters (1.5 m) and 2 m.

3. The method of claim 1, further comprising mounting the supporting relieving skirts on the wall and the roof using fasteners having a same material as the tank, the fasteners including a plate welded perpendicular to a plane of a plate support platform.

4. The method of claim 1, further comprising attaching the at least one metal sheet to the supporting relieving skirts using a self-tapping screw with a sealing rubber gasket.

5. The method of claim 1, wherein the foam glass blocks of the additional rows are characterized by: a thermal conductivity of no more than 0.05 watts per square meter of surface area for a temperature gradient of one kelvin for every meter thickness (0.05 W/mK), a vapor permeability of 0 mg/mhPa, a crushing strength of at least 0.7 Megapascals (MPa), and a density of between 115 kilograms per cubic meter (kg/m.sup.3) and 180 kg/m.sup.3.

6. The method of claim 1, wherein forming the heat-insulated layer includes installing foam glass blocks of at least one row to be offset from at least another row of foam glass blocks by a distance equal to half of a length of a foam glass block.

7. The method of claim 1, further comprising forming a recess in the foam glass blocks of the additional rows, filling the recess with an adhesive, and adhering the additional rows of foam glass blocks on the wall or the roof to couple the foam glass blocks to the tanks.

8. The method of claim 1, wherein a polyurethane sealant is used as the adhesive.

9. The method of claim 1, wherein forming the at least one vertical expansion joint includes forming multiple vertical expansion joints around a perimeter of the tank at intervals of between 4.5 m and 5.5 m.

10. The method of claim 1, wherein width of the vertical and horizontal expansion joints is (203) mm.

11. The method of claim 1, wherein the shock-absorbing sealing gasket is glued around the perimeter of each of the detachable foam blocks.

12. The method of claim 10, wherein the shock-absorbing sealing gasket has a thickness between 20 and 25 mm.

13. The method of claim 10, wherein the shock-absorbing sealing gasket is made of a cellular rubber material.

14. The method of claim 1, wherein the tank volume is between 200 to 20,000 m3.

15. The method of claim 1, wherein the coupling supporting relieving skirts to the tank comprises coupling at least three supporting relieving skirts.

16. The method of claim 1, further comprising connecting overlapping parts of the at least one metal sheet by pop rivets.

17. The method of claim 1, wherein each of the detachable foam glass blocks is coupled at an outer surface to a metal plate that protects the block from mechanical impact.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The features of the disclosure are illustrated by the following drawings.

(2) FIG. 1 illustrates a front side view of a scheme of the heat insulation on the tank wall;

(3) FIG. 2 illustrates a side view of the scheme of the heat insulation on the tank wall of FIG. 1;

(4) FIG. 3 illustrates a side view of a scheme of heat insulation on a tank roof

(5) FIG. 4 illustrates a front view of a scheme of heat insulation of lids and pipe branches on a tank wall;

(6) FIG. 5 illustrates a side view of a scheme of heat insulation on a tank bottom;

(7) FIG. 6 illustrates generally a quick-detachable heat-insulating element of a corner weld joint in a wall-bottom of a tank;

(8) FIG. 7 illustrates a scheme for fastening of supporting discharge skirts; and

(9) FIG. 8 illustrates a front view of a scheme for fastening of a top coat on a tank wall.

DETAILED DESCRIPTION

(10) The drawings include the following elements along with their corresponding reference numbers: 1.tank bottom, 2.tank wall, 3.tank roof, 4.the tank pipe branches and manholes, 5.the tank supporting relieving skirt, 6.the tier between supporting relieving skirts, 7.cellular glass blocks for heat insulation of tank walls and roof, 8.lower supporting relieving skirt, 9.corner weld joint wall-bottom of the tank (annular plate of the tank bottom), 10.removable cellular glass blocks, 11.shock-absorbing sealing gaskets for the removable blocks, 12.removable block metal plate, 13.adhesive material, 14.tank wall horizontal expansion joint, 15.tank wall vertical expansion joint, 16.tank wall heat insulation top coat (smooth metal sheet), 17.tank roof heat insulation top coat (corrugated metal sheet), 18.fastening element plate, 19.the support platform for mounting the supporting relieving skirt, 20.galvanized self-tapping screws with sealing rubber gaskets, 21.pop rivet, 22.reinforced concrete pilework, 23.leveling blanket, 24.a layer of bituminous mastic, 25.foam glass blocks for tank bottom heat insulation, 26.waterproofing layer, 27.tank roof canopy, 28.collars of the pipe branches and manholes on the tank wall and roof, 29.an underlay sheet of the pipe branches and manholes of the tank, and 30.a cover sheet of the pipe branches and manholes of the tank.

(11) The claimed method is carried out as follows.

(12) The foundation (base) is prepared, which includes the installation of a cylindrical tank, including the installation of a bottom 1 of the tank, a wall 2 of the tank, and a roof 3 of the tank. Then, supporting structures are mounted on the tank wall and roof for aiding in installation of, and supporting, heat insulating material. The supporting structures include supporting relieving skirts 5 that form tiers 6 (with brief reference to FIG. 1). Supporting relieving skirts 5 are made, e.g. of steel, in the form of beams or corners. In this case, the supporting relieving skirts are attached to the wall around the perimeter of the tank and to the roof in concentric circles at distances of between 1.5 m and 2 m of each other. If the distance between skirts exceeds 2 m, deformation of the heat insulating material may occur. If the distance between the skirts is less than 1.5 m, the specific consumption of metal for the structure significantly increases. The number of supporting relieving skirts mounted on the tank wall and roof is determined based on the geometric dimensions of tanks of different capacities.

(13) The supporting relieving skirts 5 are mounted using fasteners made of the same material as the tank (steel), and include a plate 18 welded to a plate support platform 19 and oriented perpendicular to the plane of the plate support platform 19 (with brief reference to FIG. 7). The plate support platform 19 supports the plate 18. Supporting relieving skirt fasteners are welded to the tank surface at distances of 1.5 m or less therebetween on the perimeter of the side wall and around the circumference of the roof. After the installation of the fastening elements, the tank outer surface and the supporting structure for the heat insulation are protected by weather resistant anticorrosive coatings.

(14) Then, the foam glass blocks (including, for example, cellular glass) 7 are set on the base of the supporting relieving skirt 5 by tiers starting from the bottom. A lower tierbetween the lower supporting relieving skirt 8 and the annular plate of the tank bottom 9 (around the corner weld joint)one row of foam glass blocks 10 are installed and made removable. This provides the ability for quick extraction of the blocks 10 for easy access to a corner weld joint wall-bottom 9.

(15) Removable blocks 10 of the lower layer are made with a shock-absorbing sealing gasket 11 (with brief reference to FIG. 6) having a thickness between 20 mm and 25 mm. The gasket 11 is made, for example, using a cellular rubber substance (such as foam rubber) of brands K-Flex or Armaflex. The sealing gaskets are glued around the perimeter of the block onto its end sides (bottom, top and the two side), allowing the blocks to snugly fit with each other. The gasket also allows the blocks 10 to be removable.

(16) A metal plate 12 in the form of a smooth galvanized steel sheet, being 0.7 mm thick with a tolerance of 0.08 mm, is made to have an anticorrosive coating on the outside. The plate 12 is coupled to the outer (front) surface of the removable blocks 10 using bituminous mastic and protects the blocks against mechanical impacts. For protection against mechanical impacts, installation of a metal plate with anticorrosive coating may also be positioned on the inner surface of the block. The size of the removable blocks is determined based on the location of lower supporting skirt.

(17) Other wall tiers and the roof of the tank are filled with additional foam glass blocks, which are attached to the tank surface and to each other using an adhesive material 13. The adhesive material may include, for example, a Polyurethane sealant of grade 3M. The joints between adjacent blocks and between blocks and the tank structural elements are filled with polyurethane sealant applied around the blocks perimeter. The layer of polyurethane sealant may have a width of 3 mm plus or minus 1 mm that provides a balance between strength and flexibility of construction. The blocks are placed in several rows with offset blocks in adjacent rows, as shown in FIG. 1. The offset may be, for example, half of a block length.

(18) The cuboid foam glass blocks are formed with a cruciform recess on a side that contacts the tank. The cruciform recess is formed to have two grooves (cavities) intersecting at right angles in the center of the side of the block that is in contact with the tank surface. The grooves have a cross-sectional shape in the form of a semicircle having a diameter of 20 mm with a tolerance of 2 mm, and pass along the entire surface of the block to the ribs. To mount the blocks to the tank surface, the cruciform recess is completely filled with polyurethane sealant, and the adhesive material protrudes beyond the block by between 8 mm and 12 mm to provide an improved coupling of the block with the tank surface.

(19) The walls and roof insulating blocks 7 are foam glass blocks having dimensions of 450 mm by 300 mm and a thickness of between 25 mm and 125 mm. The insulating blocks 7 have the following characteristics: a thermal conductivity of no more than 0.05 watts per square meter of surface area for a temperature gradient of one kelvin for every meter thickness (0.05 W/mK), a vapor permeability of 0 mg/mhPa, being in the NG flammability group, a crushing strength of at least 0.7 Megapascals (MPa), and a density of between 115 kilograms per cubic meter (kg/m.sup.3) and 180 kg/m.sup.3.

(20) Installation of the heat insulation is performed scaffolding. When the heat insulation is mounted along a tank section perimeter, the scaffolding is moved by the tank generatrix, and heat insulation is mounted on the entire height of an adjacent section.

(21) When mounting blocks on the tank surface, the expansion joints are formed by installing blocks and/or their partial blocks with a gap therebetween, which is filled, for example, with butyl rubber sealant of grade 3M. In this case, at least one horizontal expansion joint 14 is formed on the tank wall. At least 10 vertical joints 15 are formed being in each section (with brief reference to FIGS. 1, 2). At least ten expansion joints are formed on the tank roof in each tier and are oriented radially. The size of the gap for the formation of expansion joints is 20 mm plus or minus 3 mm.

(22) Vertical expansion joints 15 are positioned, for example, at 5 m intervals along the tank perimeter, and the horizontal joint 14 is placed, for example, between the second and the third supporting relieving skirts (such as in the middle of the two skirts). To ensure the continuity of the wall vertical expansion joints with the roof expansion joints of the tank, foam glass blocks are cut while in place.

(23) Thus, the location of expansion joints, the material they filled with, and the size of the joints compensate for deformation of the tank under external mechanical stress, preserving the integrity of the heat insulation.

(24) The metal sheet coating layers 16, 17 are mounted on the outer surface of the foam glass blocks 7 of the tank wall and roof and protect the blocks 7 from mechanical damage and environmental influences. The metal sheet coating layers 16, 17 include sheets of galvanized steel having a thickness of 0.7 mm with a permissible deviation of 0.08 mm, and are made to have anticorrosive coating on the outside. Profiled (i.e., corrugated) sheets having a thickness between 10 mm and 35 mm, and a width of not less than 1,000 mm, are used for the top coat 16 of the tank wall heat insulation. Smooth sheets having a minimum width of 1,000 mm are used for the top coat 17 of the roof heat insulation.

(25) The metal sheets are glued to the foam glass blocks, for example, using a polyurethane sealant, and are fastened to the supporting relieving skirts 5 using galvanized self-tapping screws 20 with sealing gaskets. The screws 20 with sealing gaskets are installed in holes that are jointly drilled in the sheet and the supporting relieving skirt 5 (with brief reference to FIG. 7). The sheets are coupled (i.e., the screws 20 are installed) at a distance of 300 mm plus or minus 5 mm along the tank perimeter, which ensures their snug fit to each other and to the heat insulating layer. The overlap of top coat sheets is connected using aluminum rivets 25 also at a distance of 300 mm plus or minus 5 mm (with brief reference to FIG. 8). The sheets overlap horizontally by a distance of 50 mm plus or minus 5 mm, and by one step of the corrugation profile in the vertical direction. The chosen values preserve the mutual arrangement of sheets and the continuity of the structure at longitudinal and transverse locations of the tank walls.

(26) The ledgeor canopy 27on the roof 3 is located at the junction of the roof 2 top coat and the wall top coat to prevent contamination of the tank wall 2 from mud flows (with brief reference to FIG. 3). The lay-in type panels of galvanized steel sheets are mounted to fix the top coat 17 on the surface of the blocks on the tank roof 2. Top coat sheets are attached to lay-in type panels using self-tapping galvanized screws with sealing gaskets that are installed in holes drilled through the sheet and the lay-in panel.

(27) Collars 28 made of sheet steel and having a thickness of 5 mm are welded on the pipe branches and manholes 4 on the tank wall and roof (with reference to FIG. 4). A doubling sheet 29 of galvanized steel is set under a cover sheet 30 to enhance tie-ins of the pipe branches and manholes. The cover sheet 30 for the pipe branches and manholes is mounted to the collar 28 and to the doubling sheet 29 using the self-tapping screws 20. The joint of the backing sheets, cover sheet and collar is sealed using mastic.

(28) Weatherproof anticorrosive coatings that include epoxy and/or polyurethane are used as a top coat anticorrosive coating for the pipe branches and manholes 4 on the wall and roof.

(29) Installation of the tank bottom heat insulation 1 includes the installation of concrete ring (pilework) 22. A leveling layer 23, intended for leveling the surface for laying the foam glass blocks, is then placed on the concrete ring 22. The leveling layer 23 includes, for example, cement screed or medium-grain sand with a minimum thickness of 50 cm (with brief reference to FIG. 5). The leveling layer is covered with a layer of bitumen mastic 24, and the insulation layer is laid on it. The insulation layer is made of foam glass blocks 25 having dimensions of 600 mm by 450 mm and a thickness between 40 mm and 180 mm. The blocks 25 have the following characteristics: a thermal conductivity of no more than 0.05 watts per square meter of surface area for a temperature gradient of one kelvin for every meter thickness (0.05 W/mK), a vapor permeability of 0 mg/mhPa, being in the NG flammability group, a crushing strength of at least 0.9 Megapascals (MPa), a density of between 130 kilograms per cubic meter (kg/m.sup.3) and 180 kg/m.sup.3, a length and width of about 450 mm by 600 mm and thickness of between 40 mm and 180 mm. Foam concrete blocks may also be used as the heat-insulating material of the tank bottom.

(30) When mounting the heat insulation layer, the cutting of the foam glass blocks in place is allowed. The joints between the blocks are filled with bitumen mastic (an adhesive for the bottom), the mastic layer having a width of 3 mm plus or minus 1 mm. The waterproofing layer 26 has a thickness between 1 mm and 3 mm, and is designed to protect the tank bottom 1 from surface corrosion and provides the uniform distribution of the load on the heat insulation. The waterproofing layer 26 provides elimination of local stress concentrations in the heat insulation during installation and operation of the tank and is applied on the heat insulating layer. Grades I-III bituminous concrete, for example, is used for the waterproofing layer 26.

(31) The application of the proposed method ensures the preservation of the integrity of the heat insulation in the longitudinal and transverse directions of the tank walls; provides insulation of the tank walls, roof and bottom from the effects of low ambient temperatures; and also prevents cooling of the stored fluid in the tank and thawing of soil. The construction performance of the heat insulation provides the possibility of dismantling and re-assembling for tank maintenance and repair, including the quick access to corner weld joint of the tank walls.