BRPI0803360A2 - floating roof emergency drain - Google Patents

Abstract

EMERGENCY DRAIN FOR FLOATING CEILING TANKS. The present invention relates to an emergency drainage device for liquids, usually rainwater, accumulated on the floating roof of a floating roof type tank in the event of failure of the normal drainage system. It is made up of a drainage pipe (1) fixed to the floating ceiling plate (2) so that its top is just above the floating ceiling. The drainage pipe (1) receives a flange (6) at its top and a reservoir (3) at its base and is long enough for the water column inside to create the pressure necessary to force the accumulated water to flow. over the floating ceiling into the tank interior. The invention further features a drain closure assembly. The closure assembly consists of a flange (7), an inner threaded joint (8) and a pipe (9), the top of which is bent 180 ° to prevent water or dirt from entering. Under normal fuel tank operating conditions, the closure assembly (7, 8 and 9) will remain bolted to the drain pipe flange (6) and will only be removed if the emergency drain is required.

Description

EMERGENCY DRAIN FOR FLOATING CEILING TANKS

FIELD OF INVENTION

The present invention relates to an emergency emergent drainage device, usually rainwater, accumulated on the floating roof of a floating roof type tank in the event of a failed normal drainage system. In particular, the present invention applies to tanks used for the storage of petroleum and fuel derived from it.

BACKGROUND OF THE INVENTION

A floating roof tank consists of curved plates welded together, forming a vertical cylindrical body (called the side), closed at the bottom and open at the top, inside which liquid products are stored. Floating on this product is a floating ceiling that isolates the product from contact with the atmosphere. Among the ceiling type models one of the most common is the pontoon type (or pontoon), which consists of a float in the periphery and which supports a steel plate that covers the product contained in the tank.

Floating ceiling tanks are widely used for storing petroleum and its derived fuels due to their feature of minimizing the space for vapor formation, regardless of the amount of fuel stored. In addition, they allow to contain almost all of the vapor formed in a confined space that does not pose a risk of leakage to the environment. These are characteristics of great importance both for safe fuel handling operations and for the preservation of the environment.

This type of tank also presents some problems, one of which is the risk of liquid accumulation on the floating ceiling. Commonly, this liquid is rainwater. If this buildup exceeds a certain limit, it will create a load on the floating ceiling above what it was designed to withstand, which may lead to its collapse. It is therefore necessary for the floating ceiling to have a drainage system of this liquid.

RELATED TECHNIQUE

The alternative adopted for draining rainwater that accumulates on the roof is to place drains that drain the water through hoses or hinged pipes passing through the stored fuel and release it to the outside of the tank near its base.

This is a simple and effective solution that uses gravity itself to drain water. Examples of such an alternative are shown in US Patent Documents 4,214,671 and US 4,248,357. The first uses a hinged pipe system to drain rainwater, which accompanies the up and down movement of the floating ceiling. The second is a coiled spiral hose to produce the same effect.

However, in view of the possibility of failures in the operation of the drainage device, such as clogging, it is necessary to provide an emergency drainage system for this situation. Known emergency systems are based on devices that allow any water accumulated on the floating roof to flow into the tank. This water accumulates in the deep end and is subsequently removed by appropriate means. Water that is removed from the tank becomes contaminated by the product contained in it and needs to be decontaminated before being discharged into the environment.

In the construction of the emergency drain, it must be taken into account that due to the weight of the ceiling and any water accumulated on it, the product below the center plate is pressurized, so the water accumulated on the ceiling needs something that provides energy for it to flow. into the tank. This can be achieved using the force of gravity and the density difference between the water and the stored product.

One type of emergency drain is shown in patent document JP 5.077.883. It consists of a float placed over a welded pipe to the floating ceiling that communicates with the interior inside. If liquid accumulates on the ceiling, the float will rise, allowing it to flow into the tank. Once accumulated liquid is drained, the float will close the tube again. This drain is not suitable for use in pontoon roof tanks, as the fuel is near the roof plate, which may allow the fuel to eventually drain to the ceiling due to increased pressure inside the tank or by fluctuating water. slip into the tank. Also, because of how long the float usually remains unused and the consequent buildup of dirt between it and the pipe, it may occur that they will adhere to each other and fail when they become necessary.

Another type of emergency drain is shown in US Patent No. 4,134,515. It consists of a siphon installed in the tetoflutuante whose bottom is inside the tank and is closed by a tear-off. When the roof fills with water above a certain level, a spring-loaded device activates and breaks the seal, allowing water to drain into the tank. This drain has the disadvantage of having a relatively complex operation and is therefore more susceptible to failure and also having a higher cost.

The present invention proposes a new type of emergency drain which, unlike those shown above, does not require moving parts, is quite simple in construction and can be used in pontoon roof tanks, thereby eliminating the drawbacks presented by the drains described in the patent documents. US 4,134,515 and JP 5,077,883. SUMMARY OF THE INVENTION

The present invention relates to an emergency drain which contains a U-tube with water on one side and product on the other, so as to take advantage of the gravity force and physical properties of the fluids. The greater the height of this U-tube and the difference in density between water and fluid, the greater the pressure difference that the gravity force will create to provide the desirable flow of water to the interior of the tank, as well as to prevent outflow of fuel to the outside. In this invention, a tube, the top of which is just above the floating ceiling and whose base contains a reservoir that remains filled with water, is attached to the floating ceiling. The water column inside the tube, on the one hand, and the water in the reservoir plus the fuel above the reservoir water, on the other, constitute the U-tube that creates the necessary conditions for draining the accumulated water over the floating ceiling and for prevent backflow of fuel to the ceiling.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 shows a vertical section through the emergency drain of the present invention.

Figure 2 shows a horizontal section of the drain as shown in Figure 1.

DETAILED DESCRIPTION OF THE INVENTION

In order to facilitate understanding of the invention, its detailed description will be made based on the accompanying figures and is an integral part thereof.

The emergency drain of the present invention basically consists of a drainage pipe (1) and a reservoir (3). The invention is complemented by a drain closure assembly (7, 8 and 9) and the assembly auxiliary elements .

The drainage pipe (1) is fixed to the floating ceiling plate (2), by welding or similar means, using a reinforcing ring (5). In the lower part of the drainage pipe (1) a reservoir (3) is fixed. At the top of the drainage pipe (1) a flange (6) is welded. Preferably, the flange (6) should be a few inches above the floating roof plate (2) to prevent water that can be drained from the main drain from mixing with the product, requiring further treatment to be discarded in the environment. The length of the drainage pipe (1) should be sufficient for the water column inside to exceed the fuel pressure within the tank as detailed below.

Preferably, said reservoir (3) is constructed from a tube closed at the bottom by a plate welded to it. The service diameter (3) must allow it to contain a volume of water greater than the capacity of the drainage pipe (1) and have a height difference to the drainage pipe (1) sufficient for the water column inside the drainage pipe. Drainage (1) Create the necessary back pressure both to prevent the backflow of fuel and to allow any water accumulated over the floating ceiling to drain. It is important that the reservoir (3) contains a larger volume of water than the drainage pipe (1) as a safety feature to prevent fuel from reaching the drainage pipe (1), otherwise the fuel could leak into the floating roof. because it is less dense water.

The reservoir (3) is fixed to the drainage pipe (1) by means of plaques (4) welded to the outer face of the drainage pipe (1) and to the inner face of the reservoir (3) or other means. The bottom of the reservoir (3) should be just below the lower end of the drainage pipe (1) to allow water to drain from the drainage pipe (1) into the reservoir (3). The upper part of the reservoir (3) is opened to allow the accumulated water in the floating ceiling to drain into the tank in an emergency situation. To eliminate the need for periodic supplementation of water into the reservoir (3) when the main drain is operational. The fitting of a dodrain closure assembly is foreseen. The closure assembly consists of a flange (7), bolted to the flange (6) of the drainage pipe (1), an inner threaded union (8), welded to the flange (7) and a pipe (9), threaded to the joint whose top is curved 180 ° to prevent water or dirt from entering. The length of the pipe (9) should be sufficient so that, in the event of a lack of water in the reservoir (3), the pressure of the fuel column rising to it counterbalances the overpressure within the tank, preventing fuel from spilling onto the roof. floating. Under normal fuel tank operating conditions, the locking assembly (7, 8 and 9) will remain bolted to the drainage tube flange (6) (1).

Should the main drain become unavailable due to some maintenance, maintenance personnel will check the water level in the reservoir (3), completing it if necessary, and remove the closure assembly (7, 8 and 9), leaving the flange (6) Drain pipe (1) open to space above floating ceiling. Thus, the emergency drain will be ready to drain the water in case of any rain during the unavailability of the main drain. In this situation, the water reservoir (3) and drainage pipe (1) will be filled with water and the space below the floating ceiling will be filled with liquid hydrocarbons of less than 0.9 density (such as oil, diesel, gasoline, etc.). ). If some rain occurs during this period of unavailability of the main drain, when the accumulated rainwater over the floating ceiling exceeds the level of the drainage pipe flange (6), the water flow from the ceiling to the interior of the tank will begin. and will remain until the water level is below the flange (6) of the drainage pipe (1). The "U" pipe that generates the pressure difference to allow accumulated water over the floating ceiling to flow into the tank, It is formed, on the one hand, by the water inside the drainage pipe (1) above the height of the water reservoir (3), and, on the other hand, by the product outside the same pipe (pressurized by the weight of the ceiling and the accumulated water on it). ), ie inside the tank.

The "U" pipe that prevents product flow from the interior of the tank to the ceiling is formed by the water side by the height of the drainage pipe (1) and the product side by the product outside the same pipe, as explained. above. Or, in the case of lack of reservoir water (3), by the product column rising into the tube (9) of the drain closure assembly (7, 8 and 9), on one side, and by the product outside the drain pipe (1) on the other side.

Therefore, the greater the height of the drainage pipe and the lower the height of the water reservoir, the greater the operating flow and product flow safety to the ceiling.

Although the "EMERGENCY DRAIN FOR TETOFLUCTANT TANKS" just described with reference to the accompanying drawings appears to be the preferred embodiment of the invention, it will be understood that a number of modifications may be made without departing from the scope of their protection. Some elements may be replaced by others with the same technical function, in particular the materials used, their dimensions, shapes and proportions.

Claims (10)

1. . EMERGENCY DRAIN FOR FLOATING CEILING TANKSCharacterized by a drainage pipe (1) and a reservoir (3), the drainage pipe (1) is fixed by its upper part to the floating roof plate (2) of a storage tank. and the reservoir (3) attached to the bottom of the drainage pipe (D- EMERGENCY DRAIN FOR FLOATING CEILING TANKS according to claim 1, characterized in that the drainage pipe (1) is fixed to the floating ceiling plate (2) by welding or similar means, using a safety ring. reinforcement (5). EMERGENCY DRAIN FOR FLOATING CEILING TANKS according to claim 1, characterized in that the reservoir (3) is fixed to the drainage pipe (1) by means of welded sheets (4) or equivalently fixed to the face. drainage pipe (1) and the reservoir inner face (3), with the bottom of the reservoir (3) just below the lower end of the drainage pipe (1) to allow water to drain drainage pipe (1) into the reservoir (3). EMERGENCY DRAIN FOR FLOATING CEILING TANKS according to claim 3, characterized in that the upper part of the reservoir (3) is opened into the tank, allowing accumulated water in the floating roof to drain into the tank in one location. of emergency. EMERGENCY DRAIN FOR FLOATING CEILING TANKS according to claim 1, characterized in that the drainage pipe (1) has welded a flange (6) on its top, which flange (6) is preferably a few centimeters above. of the floating roof plate (2). EMERGENCY DRAIN FOR FLOATING CEILING TANKS according to claim 1, characterized in that the drainage pipe (1) is of sufficient length that the water column in the interior overcomes the liquid overpressure inside the tank. when the reservoir (3) is full of water, to allow water accumulated on the floating roof to drain into the tank. EMERGENCY DRAIN FOR FLOATING CEILING TANKS according to claim 1, characterized in that the reservoir (3) contains a greater volume of water than the capacity of the drainage pipe (1) and has a height difference to the pipe. Drainage (1) sufficient for the water column inside the drainage pipe (1) to create the necessary back pressure both to prevent the backflow of fuel and to allow the accumulated water to flow out of the ceiling. EMERGENCY DRAIN FOR FLOATING CEILING TANKS according to claim 1, further comprising a closure assembly composed of a flange (7) screwed to the flange (6) of the drainage pipe (1), an inner threaded coupling (8) welded to the flange (7) and a pipe (9) threaded to the coupling whose top is curved 180 ° to prevent water or dirt from entering. EMERGENCY DRAIN FOR FLOATING CEILING TANKS according to claim 8, characterized in that the pipe length (9) is sufficient so that, in the event of a lack of water in the reservoir (3), the pressure of the fuel column rises until it counterbalances the overpressure inside the tank, preventing fuel from spilling onto the floating roof. EMERGENCY DRAIN FOR ROOF TANKS according to claims 1, 8 and 9, characterized in that the closure assembly (7, 8 and 9) remains screwed to the flange (6) of the drainage pipe (1) under normal conditions. operation pointanque, and will only be removed if the emergency drain is required.