Title of Invention	A TANK FOR STORING A LIQUID AT AMBIENT TEMPERATURE AND PRESSURE
Abstract	The present invention relates to a tank for storing a liquid at ambient temperature and pressure comprising a tank bottom, a circle cylindrical side wall, a dome and an internal floating cover, characterized in that the dome is arranged over the upper edge of the circle cylindrical side wall with a spacing, and in that the tank bottom is located on a rigid foundation.

Full Text

The present invention relates to a tank for storing a liquid at ambient temperature and pressure. Such a tank is for example a tank of large dimensions for storing a hydrocarbon oil. For example the diameter of such a tank is in the range of from 15 to 80 m, and the height is in the range of from 10 and 2 5 m. French patent specification No. 1 118 496 discloses a tank for storing a liquid at ambient temperature and pressure comprising a tank bottom, a circle cylindrical side wall and a dome, wherein the tank furthermore includes an internal floating cover. Such a tank is placed on the ground. It is an object of the present invention to improve the known tank by providing a tank having an improved ventilation, which tank is cheap to construct and easy to clean. To this end the tank for storing a liquid at ambient temperature and pressure according to the present invention comprises a tank bottom, a circle cylindrical side wall and a dome, wherein the dome is arranged over the upper edge of the circle cylindrical side wall with a spacing, wherein the tank furthermore includes an internal floating cover, and wherein the tank bottom is located on a rigid foundation. The improved ventilation is obtained by the spacing. Normally, the internal floating cover is provided with supports suspended from it, The tank of the present invention has a rigid foundation, and this allows putting supports for the internal floating cover on the tank bottom. Not only is the internal floating cover lighter, but the height of the supports can be selected so that the volume of the space below the internal floating cover when resting on the supports is minimized. When it is required that an operator gets under the internal floating cover, it can be lifted by an air flow and higher temporary supports can be placed on the tank bottom. The rigid foundation of the tank bottom can be arranged above ground level so as to allow detecting leakage of the tank bottom. Moreover the elevated rigid foundation makes it possible that the tank is provided with draining means for removing all liquid from the tank. Reference is made to German patent specification No. 30 15 588, which publication discloses a fully closed tank for storing fluids which is supported on a rigid support. This publication is not relevant to the present invention because the known tank is of a different type. The invention will now be described by way of example in more detail with reference to the accompanying drawings, wherein Figure 1 shows schematically a cross-section of the tank according to the present invention; and Figure 2 shows schematically a cross-section of the lower part of the tank according to the present invention with an alternative foundation. Reference is now made to Figure 1. The tank 1 for storing a liquid at ambient temperature and pressure according to the present invention comprises a tank bottom 3 and a circle cylindrical side wall 4. The tank bottom 3 and the side wall 4 are made of a suitable steel. The tank 1 has an inlet-outlet opening 6 provided with a flange for connecting a conduit (not shown) for loading or unloading the tank 1. The tank 1 further comprises a dome 7, which is made of a light weight material. The dome 7 is arranged over the upper edge 8 of the circle cylindrical side wall 4 supported by a plurality of vertical bars 9 (only one is shown). The upper edge 8 and the outer edge 10 of the dome 7 define a spacing 11, the outer edge 10 extends in horizontal direction between 0.5 and 0.8m over the upper edge 8, and in horizontal direction between 0.3 and 0.6m. The tank 4 furthermore includes an internal floating cover 12 provided with a seal 13 at its perimeter. The internal floating cover 12 is suitably made of a light weight material, such as a reinforced plastics material. The tank bottom 3 is located on a rigid foundation 16 made suitably of reinforced concrete. The rigid foundation 16 consists of a rigid lower plate 20 and a rigid, elevated upper plate 22 on which the tank bottom rests 3, and spacing members in the form of walls 26 arranged between the lower plate 2 0 and the elevated upper plate 22. The number of spacing members is suitably between 10 and 20. The lower plate 20 is supported directly by the ground 24. The upper plate 22 of the rigid foundation 16 is elevated above the level 25 of the ground 24. The height of the rigid foundation is 2.5 m. The tank 1 comprises supports 3 5 for the internal floating cover 12 which supports 3 5 are located on the tank bottom 3. The height of the supports 35 is suitably such that, when resting on the supports 35, the internal floating cover 12 floats just above the inlet-outlet opening 6. As the way in which the side wall 4 is joined to the tank bottom 3 is known, this will not be discussed here in detail. During normal operation, the tank 1 is filled with liquid through the inlet-outlet opening 6, and the internal floating cover 12 floats on the liquid 37 in the tank 1. The dome 7 protects the internal floating cover 12 from rain, snow and wind. Since the dome 7 is arranged with a spacing 11 over the upper end of the side wall 4, there is sufficient ventilation to prevent formation of an explosive mixture above the internal floating cover 12. The tank can furthermore be provided with a drain 40, which includes a conduit 41 extending through the rigid foundation 16. The conduit 41 is provided with a valve (not shown) and it is connected to a discharge conduit (not shown). When the tank 1 needs to be cleaned, the liquid level in the tank 1 is lowered by allowing the tank 1 to unload through the inlet-outlet opening 6. In the tank 1 remain the so-called bottoms, and the bottoms can easily be removed by circulating a liquid cleaning composition through the inlet-outlet opening 6 and the drain 40. This cleaning operation can be safely done without an operator in the tank. The flow of liquids to the drain 40 can be facilitated when the tank bottom 3 is so shaped that the inlet of the drain 40 is below the level of the edge between the side wall 4 and the tank bottom 3. In an alternative embodiment shown in Figure 2, the rigid foundation 16 consists of a single elevated rigid plate 22' supported by piles 40. CLAIMS 1. Tank for storing a liquid at ambient temperature and pressure comprising a tank bottom, a circle cylindrical side wall and a dome, wherein the dome is arranged over the upper edge of the circle cylindrical side wall with a spacing, wherein the tank furthermore includes an internal floating cover, and wherein the tank bottom is located on a rigid foundation. 2. Tank as claimed in claim 1, wherein the tank comprises supports for the internal floating cover which supports are located on the tank bottom. 3. Tank as claimed in claim 1 or 2, wherein the rigid foundation is elevated. 4. Tank as claimed in anyone of the claims 1-3, wherein the rigid foundation consists of a rigid lower plate and a rigid upper plate on which the tank bottom rests, and spacing members arranged between the lower and the upper plate. 5. Tank as claimed in anyone of the claims 1-4, wherein the rigid foundation is supported by piles. 6. Tank for storing a liquid at ambient temperature and pressure comprising a tank bottom substantially as herein described with reference to the accompanying drawings.

Documents:

1073-mas-1997-abstract.pdf

1073-mas-1997-claims filed.pdf

1073-mas-1997-claims granted.pdf

1073-mas-1997-correspondnece-others.pdf

1073-mas-1997-correspondnece-po.pdf

1073-mas-1997-description(complete)filed.pdf

1073-mas-1997-description(complete)granted.pdf

1073-mas-1997-drawings.pdf

1073-mas-1997-form 1.pdf

1073-mas-1997-form 26.pdf

1073-mas-1997-form 3.pdf

1073-mas-1997-other documents.pdf