System and method for selective extraction of viscous hydrocarbons from tanks and other containers

Abstract

The present invention proposes a system and method for selectively extracting viscous hydrocarbons from tanks and other containers. The system comprises the following components for heating hydrocarbons: a steam ejector 3 generates vortex diffusion of the motive steam together with gas drawn in by the Venturi effect, and a surrounding heating conduit 5 is attached externally to the tank or container. The method includes the following operations: heating the surface layer of hydrocarbons with gas injected by the steam ejector, causing the selective flow of hot hydrocarbons to the surroundings; local heating of the hydrocarbons by the surroundings, causing water precipitation and the selective flow of the hottest hydrocarbons to an extraction pump; and extracting the precipitated water and hydrocarbons that selectively flow from the surroundings with two pumps.

Description

Technical Field

[0001] The present invention relates to a system and method for selectively extracting viscous hydrocarbons from storage tanks and other containers that must be periodically emptied and cleaned for periodic inspection, repair, load change, disassembly, etc.

[0002] The purpose of the system and method of the present invention is applicable to storage tanks and other containers containing viscous hydrocarbons existing in petroleum refineries, petrochemical plants, thermal power plants, port terminals, etc. Floating roof (or floating roof type) oil tanks and hydrocarbon process units, including distillation towers, reactors, fan coolers, containers with gaseous hydrocarbon "demisters", interconnecting pipes, etc., constitute typical examples of the application of the present invention.

[0003] Among the viscous hydrocarbons to which the present system and selective extraction method are applicable, it is necessary to point out hydrocarbons (class B, flash point <55°C) accumulated at the bottom of the oil tank, heavy oil (class C, flash point included between 55°C and 100°C), and asphalt (class D, flash point >100°C).

[0004] US3874399A discloses a method for discharging high-viscosity hydrocarbons from a tank by recirculating preheated discharged hydrocarbons in the tank to reduce the viscosity of the contents in the tank and facilitate its discharge.

[0005] ES417373A1 describes a method for purging combustible waste from a container, including passing a gas stream containing inert gases such as steam and nitrogen through the container, where the gas stream introduced into the container has a steam content of 4 - 50% by volume and introduces sufficient heat into the container to reach a temperature of at least 50°C.

[0006] U.S. Patent Application Publication No. 5085242A discloses a method and apparatus for removing residues from a storage tank by locally heating the tank with steam, water vapor, or electricity and flowing hydrocarbons into the heated area.

[0007] GB2101475A describes a method of cleaning a storage tank with sludge by bringing it into contact with hot water (hot water injection and recirculation), which results in a temperature of 70°C, reducing viscosity and allowing for the removal of residue.

[0008] ES2391183B1(P201100464), belonging to the same inventor as the present application, discloses a method for selectively extracting high-viscosity hydrocarbons by using the steps of applying safety measures (measuring the explosiveness inside the tank for a floating-roof oil tank), heating the contents of the tank with a flexible coil slightly immersed in hydrocarbons, and heating the surface layer of hydrocarbons by injecting hot air into the tank.

[0009] Similarly, ES2544575B1(P201400060), belonging to the same inventors as this application, discloses a method for the selective extraction of residual viscous hydrocarbons in a storage tank. This method includes measuring the explosiveness of the tank, heating the hydrocarbons with a device placed inside the tank, and heating the surface of the hydrocarbons by injecting hot air. As a further step, after the extraction of hydrocarbons and the maintenance of hot air injection, hot water is injected onto the residual hydrocarbons to facilitate subsequent extraction.

[0010] Patent document WO2017118766A1(P201600007), belonging to the same inventors as this application, discloses a method for extracting viscous hydrocarbons from a tank by injecting a flow consisting of hot air and steam into the tank. A centrifugal fan or gas circulator is used to pass the flow through an electric heater equipped with a deflector that generates a vortex. This heats the air, absorbs moisture into the air, superheats the steam, and extracts the hydrocarbons. Furthermore, the hydrocarbons can be further heated by a device for local heating near the intake pipe.

[0011] Patent document WO2019197690 (P201800095), belonging to the same inventors as this application, describes a method for extracting viscous hydrocarbons from storage tanks and process equipment, which proposes injecting an inert gas into a portion of the tank or equipment until an oxygen concentration is achieved that guarantees a range of zero flammability, and then injecting a gas flow homogenized by an irreversible vortex diffusion process into the portion of the tank or equipment, which consists of gas recirculated from the portion of the tank or equipment, and amounts of water vapor and inert gas always required to maintain the oxygen concentration at a value that guarantees a range of flammability and to flow hydrocarbons in an amount equivalent to that required by an extraction pump suitable for use in a potentially explosive atmosphere.

[0012] Utility Model No. RU25176U discloses a device for washing viscous oil and sediment or sediment of petroleum products from a tank, the device comprising means for heating, liquefying, moving and mixing the sediment, the sediment comprising a hollow bar through which steam, gas or liquid circulates, the hollow bar positioned above the bottom of the sediment and comprising discharge means comprising an ejector head for transporting the steam, gas or liquid to the tank surface.

[0013] The method of the present invention differs from the prior art methods described above in that it uses a combination of a steam ejector (or steam exhauster) and a perimeter heating conduit attached to the outer wall of the tank, which aims to establish two selective hydrocarbon flows: a flow from the surface layer to a region heated by the entire extension of the perimeter conduit, and a flow from the region heated by the perimeter conduit to a pump suction device for selectively extracting hydrocarbons. This allows heating of hydrocarbons in the surface layer and hydrocarbons adjacent to the entire extension of the perimeter conduit to be heated in a localized manner.

[0014] Two elements that characterize the objective of the method of the present invention, namely the steam ejector and the ambient heating conduit, are not used in any of the prior art methods, and are unable to generate two selective flows of hydrocarbons coming from the surface layer, nor can they generate the precipitation and separation extraction of non-emulsified water, thus providing results that cannot be obtained by either of those or any combination thereof.

[0015] Therefore, the method of the present invention achieves a more selective extraction than that achieved by any or a combination thereof of prior art methods. The extraction of hydrocarbons is called "selective" because two conditions are met: the hydrocarbons are extracted separately from non-emulsified water, and mixing of hydrocarbons from the surface layer with hydrocarbons closest to the bottom of the tank or container (the latter of which are usually emulsified with water or contaminated with sludge and precipitates) is prevented during the extraction.

[0016] In the case of prior art methods based on generalized heating of hydrocarbons in a tank, such as the method of US3874399A, the extraction performed is not selective as a generalized reduction of the hydrocarbon viscosity, and therefore results in an undesirable flow of contaminated hydrocarbons from the bottom of the tank to the pump's suction duct.

[0017] Regarding prior art methods based on localized heating of hydrocarbons in a tank, such as US5085242A, the flow of hydrocarbons into the heating region is very slow or nonexistent, resulting in an undesirable flow of the most contaminated hydrocarbons from the bottom of the tank to the heating region, in addition to being far less effective and therefore no longer selective in extraction.

[0018] In the case of conventional methods that establish heating by means of injecting steam, as in ES417373A1, or that establish hot water recirculation, as in GB2101475A, extraction is not selective in either case because an undesirable flow of the most contaminated hydrocarbons occurs from the bottom of the tank to the extraction area, and hydrocarbons having condensed steam or recirculated hot water become contaminated with water.

[0019] When this method is applied to fuel oil tanks, preventing contamination by both water and undesirable flows of contaminated hydrocarbons from the bottom of the tank is fundamental to selling extracted fuel oil in compliance with legal specifications regarding water and sediment content, because small flows of contaminated fuel oil from the bottom of the tank into the pump's suction duct are usually sufficient to cause non-compliance with the aforementioned legal specifications, and all extracted fuel oil would have to be managed as waste.

[0020] Regarding the other four prior art methods mentioned above (ES2391183B1, ES2544575B1, WO2017118766A1, and WO2019197690), all four correspond to the same inventor as this application. In the last two (WO2017118766A1 and WO2019197690), the surface layer of hydrocarbons is heated with steam, which is very effective due to the high heat transfer capacity of steam, but the extraction is not selective because the hydrocarbons are contaminated with condensate from the steam injected into the tank or container. Therefore, neither the title nor the specification describing the methods of WO2017118766A1 and WO2019197690 mentions that the hydrocarbon extraction is selective. In contrast, the term “selective” appears in the title and specification of the present invention as it arises in the first and second prior art methods (ES2391183B1 and ES2544575B1), the latter two methods which establish the injection of hot air for heating the surface layer of hydrocarbons and thus avoid the contamination effect of water vapor, but they present the disadvantages of having a much lower ability to heat the surface layer of hydrocarbons and having much higher costs invested in the implementation of the apparatus and method.

[0021] In relation to the aforementioned costs, the apparatus characterizing the system of the present invention is very simple and requires only a supply of steam for operation. This advantage becomes even more apparent when considering that steam is generally readily available in viscous hydrocarbon storage facilities. In contrast, the four prior art methods belonging to the same inventor described above require the use of a considerable number of electrical devices, namely ATEX electric heaters, centrifugal fans, gas circulators, high-power generator sets, variable frequency drive devices, and electrical cabinets. In contrast, the steam ejector and surrounding piping have no mechanical or electrical components and are therefore very low-cost devices that require no maintenance, and furthermore, the steam ejector alone performs multiple functions. It draws gas from a given position in a tank or container by the Venturi effect, subjects the drawn gas to vortex diffusion treatment using its driving steam, and injects the resulting homogeneous mixture of high-temperature gas to another position in the same tank or container.

[0022] In addition to performing selective extraction with much higher heating capacity and at a much lower cost than two prior art methods (ES2391183B1 and ES2544575B1) that enable this, the method of the present invention enables more effective selective extraction. The significant reduction in viscosity due to double heating of hydrocarbons (heating the surface layer with the driving vapor of the ejector and locally heating the hydrocarbons adjacent to the entire length of the surrounding conduit) prevents the undesirable flow to the pump of hydrocarbons closest to the bottom of the tank, which are the most contaminated (and therefore remain viscous and substantially static, as they are not heated). In contrast, by using either of the two prior art methods mentioned above, hydrocarbons flow viscously through the pump's suction device, and the undesirable flow of hydrocarbons from the bottom of the tank to the pump's suction device occurs to some extent, particularly as the level (or liquid level) of hydrocarbons in the tank decreases, and during certain periods (winter in the Northern Hemisphere) when the hydrocarbons closest to the bottom of the tank are at a higher temperature than the surface temperature.

[0023] Furthermore, it should be noted that the most commonly used method in refineries for extracting viscous hydrocarbons from oil tanks is based on dilution with crude oil or low-viscosity hydrocarbons supplied by the refinery itself. The method of the present invention offers significant advantages over the aforementioned method, as it enables the extraction of hydrocarbons without mixing with contaminants from the bottom of the tank, avoids the hazardous leakage inherent in the aforementioned method in tanks with unsealed bottoms, and removes layers of hydrocarbons contaminating the inner surfaces of the tank walls and floating roofs as an additional cleaning effect. Moreover, applying the objectives of the method of the present invention requires the use of much simpler equipment, significantly reducing equipment investment costs and operating costs. With respect to other containers, the most popular methods are pressurized water cleaning and chemical cleaning, and this method has the advantage of being more effective and generating less waste. [Disclosure of the Invention] [Means for solving the problem]

[0024] The present invention relates to a system and method for selectively extracting viscous hydrocarbons from storage tanks and other containers. The hydrocarbon extraction is called "selective" because two conditions are met: the hydrocarbons are extracted separately from non-emulsified water, and mixing of hydrocarbons from the surface layer with hydrocarbons closest to the bottom of the tank or container (the latter usually emulsified with water or contaminated with sludge and precipitates) is prevented during the extraction.

[0025] According to the first embodiment, a system for the selective extraction of viscous hydrocarbons from a storage tank or container is characterized by comprising the following combination of elements: - A steam boiler having control means configured to adjust the amount and temperature of steam it supplies, wherein the temperature is between 120 and 200°C (approximately 2 to 15 bar). At least one steam ejector for the purpose of heating the surface layer of hydrocarbons to be extracted, wherein a driving steam nozzle is connected to the boiler, whereby in the diffuser of the steam ejector, vortex diffusion of the driving steam provided by the steam boiler and the gas sucked into the ejector through its suction opening due to the Venturi effect occurs, and the gas comes from the tank or the container itself, from the atmosphere, from the steam boiler (the steam is for raising the temperature of the gas exhausted by the ejector), or from a combination of the above-mentioned sources of origin. As a result, at the discharge opening of the ejector, a homogeneous mixture of high-temperature gas is obtained which the steam ejector itself injects into the tank or the container through a gas discharge duct to heat the surface layer of hydrocarbons. The steam ejector At least one pump for the selective extraction of hydrocarbons from the surface layer heated by a homogeneous mixture of high-temperature gas injected by the steam ejector, wherein the suction duct of the pump is connected to the tank or the container in the peripheral region, where hydrocarbons from the surface layer heated by the mixture of gas injected by the steam ejector flow. The pump

[0026] When the boiler supplies steam to the gas suction duct of the ejector to raise the temperature of the gas injected into the tank or the container, the steam must be depressurized so as not to impair the proper operation of the ejector and not to cause a danger of overpressure. The danger of overpressure can be eliminated by a pressure reducing valve at the outlet of the boiler, a duct having a diameter sufficient for the expansion of the steam to occur, or a second steam ejector whose gas discharge opening is connected to the gas suction opening of the ejector that injects gas into the tank or the container.

[0027] Regarding this system, it should be mentioned that since the homogeneous mixture of gas generated by vortex diffusion prevents the free upward movement of the steam injected into the tank or the container, most of the injected driving steam condenses on the surface layer of hydrocarbons, and a large amount of latent heat (539.4 cal / g at 100 °C) is transferred to it.

[0028] According to another embodiment of the present invention, the system further comprises - a peripheral conduit (5) externally attached to a portion of the metal wall of the tank or container (1) located below the level determined by the hydrocarbon to be extracted, for the purpose of locally heating the hydrocarbon, a part of the peripheral conduit (5) being constituted by the actual portion of the metal wall of the tank or container (1) to which it is attached, whereby the hot gas circulated through the peripheral conduit (5) comes into direct contact with the portion of the metal wall to locally heat the hydrocarbon adjacent to the tank or container (1), such heat transfer being a function of the area of the metal wall in contact with the hot gas, the temperature of the gas circulated through the peripheral conduit, and the thermal conductivity of the metal wall of the tank or container, the peripheral conduit (5); - at least a second pump for extracting the settled water in the tank or container, the suction ducts of the first and second pumps being connected to the tank or container in a peripheral region close to the region heated by the peripheral conduit, the pump; - a gas duct connected to the gas inlet and outlet openings of the ejector and to two different points (or positions / places) around the tank or container located above the level determined by the hydrocarbon to be extracted, at least one of the connection points of the duct of the steam ejector being close to the peripheral connection region of the hydrocarbon and settled water suction ducts, the gas duct.

[0029] In another embodiment, the present invention comprises - a first suction device connected to the end of the hydrocarbon suction duct, the suction opening of which is directed upwards, and a second suction device connected to the settled water suction duct, the suction opening of which is directed towards the bottom of the tank or container; - A peripheral heating conduit consisting of a synthetic fiber covering supported by semicircular arches distributed along the entire conduit, wherein the peripheral conduit acquires a semi-cylindrical shape in which its flat sections coincide with sections of the metal wall of a tank or container to which it is attached and sealed by two straps, and the semicircular arches have two support plates welded to their two ends for guiding and holding two straps attached to them and passing through them, so that when the two straps are tensioned at their ends at two fixed points, they press and seal the support plates of all the arches and the synthetic fiber along the entire length of the peripheral conduit and its upper and lower edges against the cylindrical wall of the tank or container (for example, a silicone-treated fiber roll that can withstand temperatures higher than 200°C and has dimensions of about 50 meters in length and 1 meter in width can be used as the synthetic fiber), the peripheral heating conduit - A steam ejector, wherein its discharge port is connected by a gas duct to an inlet port for high-temperature gas from the surrounding conduit, its drive steam nozzle is connected to the boiler, and its gas intake port draws in air from the atmosphere by the Venturi effect, thereby uniformly mixing the drawn air with the drive steam and injecting it into the inlet port for high-temperature gas in the surrounding conduit by the ejector itself. - At least one centrifugal fan or gas circulator installed in the gas intake duct of a steam ejector and configured to increase the flow rate of gas injected into a tank or container. - At least one steam ejector or connection point installed in the gas suction duct of a steam ejector that injects gas into a tank or container to raise the temperature of the gas being injected into the tank or container. - A nitrogen tank connected to a gas suction duct of a vapor ejector that injects gas into a tank or container to prevent the risk of fire or explosion in the case of hydrocarbons with a flash point of less than 55°C (Class B), and having a control means configured to adjust the amount of nitrogen supplied to the tank or container. It has.

[0030] The present invention is also applicable to the selective extraction of viscous hydrocarbons and other substances, where asphalt emulsion, oily emulsion, oily sludge, and soot can be mentioned as non-limiting examples, wherein the hydrocarbons and substances mentioned herein are exposed to gas circulation and heating conditions, and are therefore susceptible to flowing into the area surrounding a tank or container to which at least one extraction pump duct is connected.

[0031] Next, the method for selectively extracting viscous hydrocarbons from storage tanks and other containers, which is the objective of the present invention, is characterized by the following operation. An operation to heat the surface layer of hydrocarbons extracted by a steam ejector connected to a boiler that supplies steam at a temperature between -120 and 200°C, wherein the ejector draws gas from a point in a tank or container by the Venturi effect, vortex-diffuses the drawn gas with its driving steam, injects a homogeneous mixture of the resulting high-temperature gas into another point in the same tank or container, the gas intake and exhaust points of the ejector are above a level determined by the hydrocarbons being extracted, and during extraction, the amount of steam supplied to the ejector is adjusted so that a selective flow of high-temperature hydrocarbons into a region of local heating equivalent to that drawn in by a pump that selectively extracts hydrocarbons is established. - An operation in which a localized heating of hydrocarbons flowing from the surface layer is performed by a peripheral conduit externally attached to a tank or container through which a high-temperature gas is circulated, wherein non-emulsified water precipitates during extraction, and a selective flow of heated hydrocarbons is established by the peripheral conduit toward a suction device connected to a pump via a duct for selective extraction of hydrocarbons. - An operation comprising selective extraction of hydrocarbons heated by a surrounding conduit using a first pump and periodic extraction of precipitated water using a second pump, wherein the duct for hydrocarbon extraction has a suction device at one end with its suction opening directed upward, and the duct for precipitated water extraction has a suction device at one end with its suction opening directed towards the bottom of a tank or container, and the hydrocarbon suction device is immersed in the hydrocarbons heated by the surrounding conduit as described above.

[0032] When the heat supply is no longer effective and the flow of hydrocarbons to the pump's suction device ends, the extraction is terminated and the inside of the tank or container is inspected. If a considerable amount of hydrocarbons remains in a certain area of ​​the tank or container, the extraction is continued while appropriately selecting the installation point for the apparatus described above that defines the system of the present invention. At the end of hydrocarbon extraction, water, oily precipitates, or high-melting-point hydrocarbons remain at the bottom of the tank or container, and these are removed by conventional methods. In contrast, it should be emphasized that when this method is applied, the layer of hydrocarbons initially adhering to the inner surfaces of the tank walls and roof is separated and removed by the circulation of high-temperature gas inside the tank or container, in particular by heating and entrainment of water vapor as it condenses on the hydrocarbon layer.

[0033] This law should mention that the homogeneous mixing of gases due to vortex diffusion in the diffuser of the steam injector prevents the free upward movement of water vapor injected into the tank or container, so that most of the injected driving steam condenses on the surface layer of hydrocarbons, and a large amount of latent heat (539.4 cal / g at 100°C) is transferred to it.

[0034] In another embodiment of the present invention, a high-temperature gas circulated through a perimeter heating conduit is supplied by a steam ejector, the gas discharge opening of which is connected to an inlet opening for the high-temperature gas in the perimeter conduit, the driving steam nozzle is connected to the boiler described above, the gas intake opening of which draws in air from the atmosphere by the Venturi effect, the drawn-in air is homogeneously mixed with the driving steam and injected by the ejector itself into the inlet opening for the gas in the perimeter conduit.

[0035] If the tank or container contains a viscous hydrocarbon (Class B) with a flash point below 55°C, the following actions are also included: The initial action of injecting nitrogen into the tank or container until the oxygen concentration reaches less than -8%, and - A controlled supply of a constant amount of nitrogen into the aforementioned suction duct of the steam ejector to maintain the oxygen concentration in the tank or container at all times below 8%. Injecting steam into the tank or container also contributes to maintaining the oxidizing oxygen concentration below 8% (oxygen, a component of steam, is not an oxidizing agent).

[0036] As described above, when this system and method is applied to the selective extraction of Class B viscous hydrocarbons (flash point < 55°C) that accumulate at the bottom of an oil tank, nitrogen must be injected into the tank or container to maintain an oxygen concentration of less than 8% at all times. On the other hand, for Class C and D viscous hydrocarbons (flash point ≥ 55°C), such as heavy oil and asphalt, there is no risk of fire or explosion when applying the objectives of the system and method of the present invention, so injection of nitrogen into the tank or container is unnecessary.

[0037] The systems and methods of the present invention are applicable to storage tanks and other containers containing viscous hydrocarbons found in oil refineries, petrochemical plants, thermal power plants, port terminals, and the like. The methods for applying the present invention to other containers are substantially the same as those for storage tanks, except that the installation of the apparatus must be adapted to multiple configurations and sizes in each case. Examples of these latter applications include process units in refineries and petrochemical plants, including distillation columns, reactors, fan coolers, containers with gaseous hydrocarbon "demisters," and interconnecting pipes. The systems and methods can be applied to complete process units or to their components separately, in both cases, by appropriately selecting gas intake and discharge points of one or more vapor ejectors, as well as areas of localized heating of hydrocarbons, and by injecting nitrogen as a fire and explosion prevention measure. [Brief explanation of the drawing]

[0038] Figure 1 shows a floating-roof oil tank 1, and covers 2a and 2b having fittings necessary for the installation of this system and the application of this method are installed on its manhole. The steam ejector 3 draws gas from a given point in the tank via a gas suction duct 3a connected to cover 2a using the Venturi effect, and injects this gas using a gas discharge duct 3b connected to cover 2b once it has been homogeneously mixed with the driving steam supplied by the steam boiler 4 at a temperature of 120-200°C and has become hot. The boiler has a valve 4a that adjusts the amount of steam supplied to the ejector.

[0039] Furthermore, a perimeter conduit 5 is installed attached to the outer metal wall of the tank to heat oil adjacent to the total length of the perimeter conduit. In one embodiment, the perimeter conduit is connected to a second steam ejector 6 that, by the Venturi effect, draws in air from the atmosphere 6a, homogeneously mixes it with driving steam supplied by a steam boiler 4 having a control valve 4b, and discharges it into the perimeter conduit through a gas discharge duct 6b.

[0040] Pump 7 selectively extracts oil heated by the surrounding conduit through suction duct 7a, and a second pump 8 extracts settled water through suction duct 8a. The extracted oil and water are pumped separately to predetermined storage, transport, or processing points through oil and water delivery ducts 7b and 8b. The suction ducts of the aforementioned pumps have oil suction devices 7c and settled water suction devices 8c connected to their respective ends. These devices are positioned in the tank adjacent to the area heated by the surrounding conduit, with the oil suction devices having upward-facing suction openings and the water suction devices having suction openings directed towards the bottom of the tank and slightly spaced therefrom.

[0041] Assuming the hydrocarbons accumulating at the bottom of the oil tank are Class B (flash point < 55°C), a nitrogen tank 9 is provided to eliminate the risk of fire and explosion. The nitrogen tank 9 supplies a controlled amount of nitrogen to the gas suction duct of the ejector 3a via a control valve 9a. Thus, the homogenized high-temperature gas flow injected into the tank has a high nitrogen concentration, which contributes to maintaining the oxygen concentration in the tank at a constant level of less than 8%. Similarly, the injection of drive steam from the ejector also contributes to maintaining the oxidizing oxygen concentration in the tank at a level of less than 8% (oxygen, a component of water vapor, is not an oxidizing agent). [Modes for carrying out the invention]

[0042] A preferred application of this method is the extraction of viscous hydrocarbons accumulated at the bottom of floating-roof oil tanks (Class B hydrocarbons with a flash point <55°C).

[0043] The operation sequence of this method is as follows: Initial injection of nitrogen into the tank until the oxygen concentration reaches less than 8%. Subsequently, during oil extraction, the nitrogen tank 9, equipped with a control valve 9a, provides a controlled amount of nitrogen so that the oxygen concentration inside the tank is always kept below 8%.

[0044] - Heating of the oil surface layer by the steam ejector 3. This involves drawing gas from a point in the tank itself, above the level of oil to be extracted, and returning it homogeneously mixed with the amount of nitrogen necessary to maintain the driving steam and oxygen concentration below 8%. The amount of driving steam supplied to the ejector is adjusted so that a sufficient amount of oil from the surface layer flows selectively into the area adjacent to the ambient heating conduit 5, without slowing down the selective extraction of the oil.

[0045] -Local heating of the oil with the aforementioned peripheral conduit externally attached to the tank, such that when the viscosity of adjacent hydrocarbons decreases due to heating, precipitation of non-emulsified water occurs, and a selective flow of the oil heated by the peripheral conduit to a suction device 7c connected to the oil extraction pump 7 is established. The injection of hot gas into the peripheral conduit is performed using a second steam ejector 6 that draws in air from the atmosphere by the Venturi effect, homogeneously mixes it with its driving steam, and injects it into the peripheral conduit, and the steam is supplied by the steam boiler 4, the supply of which is regulated by a valve 4b.

[0046] -Selective extraction of oil heated by a surrounding conduit and extraction of sedimentary water separately using two pumps 7 and 8 (the suction devices 7c and 8c of pumps 7 and 8, respectively, are positioned in the tank adjacent to the area heated by the surrounding conduit). This allows the pumps to transfer the oil and water separately to designated locations for storage, transport, or processing.

[0047] When the heat supply is no longer effective and the flow of oil to the oil suction device 7 ceases, the extraction is complete and the inside of the tank is inspected. If a considerable amount of oil remains in a certain area of ​​the tank, the extraction is continued while appropriately selecting the placement points for the device. In large tanks, several placements for the device are possible, or it is possible to use two or more steam ejectors simultaneously, each having its own corresponding ambient heating conduit and extraction pump. At the end of the extraction, water, oily precipitates, or hydrocarbons with high melting points always remain at the bottom of the tank, and these are removed by conventional methods. In contrast, it should be emphasized that when this method is applied, the layer of oil initially adhering to the inner surfaces of the tank walls and roof is separated and removed by the circulation of high-temperature gas inside the tank, particularly by the entrainment of water vapor as it condenses on the layer of oil.

[0048] The following is the invention as originally described in the application. <Claim 1> A system for selectively extracting viscous hydrocarbons from storage tanks and other containers, -A steam boiler (4) having control means configured to adjust the amount and temperature of the steam it supplies, the temperature of which is between 120 and 200°C, - An apparatus for injecting a homogenized gas stream into the tank or container to heat the surface layer of the hydrocarbon to be extracted, - At least one pump (7) for selectively extracting the hydrocarbons from the surface layer heated by an injected homogeneous gas mixture, wherein the suction duct (7a) of the pump (7) is connected in a peripheral region to the tank or container (1) for extracting the hydrocarbons heated from the surface layer therein. It has, - The apparatus for injecting a homogenized gas flow into the tank or container comprises at least one steam ejector (3) equipped with a driven steam nozzle connected to the steam boiler (4), wherein in the diffuser of the steam ejector (3), vortex diffusion occurs of the driven steam provided by the steam boiler (4) and the gas drawn in by the steam ejector (3) through its intake opening (3a) by the Venturi effect, and the gas arrives from the tank or container (1) itself, from the atmosphere, from the steam boiler (4), or from a combination of the sources, and as a result, a homogeneous mixture of high-temperature gas is obtained at the discharge opening of the steam ejector (3) for the steam ejector (3) itself to inject into the tank or container (1) through a gas discharge duct to heat the surface layer of hydrocarbons. A system characterized by the following features. <Claim 2> -A peripheral conduit (5) externally attached to a portion of the metal wall of the tank or container (1) located below a level determined by the hydrocarbon being extracted, for the purpose of localized heating of the hydrocarbon, wherein a portion of the peripheral conduit (5) is made up of an actual portion of the metal wall of the tank or container (1) to which it is attached, and the hot gas circulating through the peripheral conduit (5) comes into direct contact with the portion of the metal wall, thereby locally heating the hydrocarbon adjacent to the tank or container (1), -At least one second pump (8) for extracting sediment from the tank or container (1), wherein the suction ducts (7a) and (8a) of the first and second pumps are connected to the tank or container (1) in a peripheral region close to the region heated by the peripheral conduit (5), - A gas duct connected to the gas intake and discharge openings of the vapor ejector (3) and connected to two different points around the tank or container located above a level determined by the hydrocarbons being extracted, wherein at least one of the connection points of the duct of the ejector is close to the connection area around the hydrocarbon and sediment water intake duct. The system according to claim 1, further comprising: <Claim 3> The system according to claim 1 or 2, wherein the hydrocarbon suction duct (7a) is connected at one end to a suction device (7c) with its suction opening directed upward, and the sediment water suction duct (8a) is connected at one end to a suction device (8c) with its suction opening directed toward the bottom of the tank or container. <Claim 4> The system according to claim 2, wherein the surrounding heating conduit (5) consists of a synthetic fiber cover supported by semicircular arches distributed along the entire length of the conduit, thereby the surrounding conduit (5) acquires a semi-cylindrical shape in which its flat section coincides with a section of the metal wall of the tank or container (1) to which it is attached and sealed by two straps, and the semicircular arches have support plates welded to their two ends to guide and hold the two straps passing through them. <Claim 5> The system according to claim 2 or 4, wherein the hot gas circulating through the surrounding conduit (5) is supplied by a second steam ejector (6), the gas discharge opening of which is connected to an inlet opening for the hot gas in the surrounding conduit (5), the drive steam nozzle of which is connected to the steam boiler (4), and the gas intake opening of which draws in air from the atmosphere by the Venturi effect, thereby homogeneously mixing the intake air with the drive steam and injecting it into the inlet opening for the gas in the surrounding conduit (5) by the second steam ejector (6) itself. <Claim 6> The system according to claim 1, wherein the gas intake duct of the steam ejector (3) has at least one centrifugal fan or gas circulator configured to increase the flow rate of gas that the steam ejector (3) injects into the tank or container (1). <Claim 7> The system according to claim 1, wherein the gas intake duct of the steam ejector (3) has at least one connection point for injecting another steam ejector or depressurized steam. <Claim 8> The system according to any one of claims 1 to 7, configured to process Class C and Class D hydrocarbons having a flash point of 55°C or higher. <Claim 9> It is configured to process Class B hydrocarbons with a flash point below 55°C. The system according to any one of claims 1 to 7, wherein the gas intake duct of the vapor ejector that injects the gas into the tank or container is connected to a nitrogen tank having a control means configured to adjust the amount of nitrogen supplied. <Claim 10> A method for selective extraction of viscous hydrocarbons from storage tanks and other containers, particularly tanks or containers (1) having floating roofs and metal walls, A method comprising heating a surface layer of hydrocarbons to be extracted by a steam ejector (3) connected to a steam boiler (4) that supplies steam at a temperature of 120-200°C, thereby causing the steam ejector (3) to draw in gases arriving from the tank or container (1) itself, from the atmosphere, from the steam boiler (4), or from a combination of the aforementioned sources through its intake opening via the Venturi effect, vortex-diffusing the drawn-in gases with its driving steam, injecting the resulting homogeneous mixture of high-temperature gases into another point in the tank or container (1), and adjusting the amount of steam supplied to the steam ejector (3) to create a selective flow for selective extraction of high-temperature hydrocarbons from the surface layer into a duct (7a) of a pump (7). <Claim 11> - An operation in which a high-temperature gas circulates in a tank or container, and a peripheral conduit (5) externally attached to the tank or container locally heats hydrocarbons selectively flowing from the surface layer, wherein during extraction, a precipitate of non-emulsified water occurs, and a selective flow of heated hydrocarbons is generated by the peripheral conduit toward a suction device (7c) connected by a duct (7a) to a pump (7) for selective extraction of hydrocarbons, - The operation involves selective extraction of hydrocarbons heated by a surrounding conduit (5) by the pump (7) and periodic extraction of sedimentary water by a second pump (8), wherein the duct for the extraction of hydrocarbons is connected at one end to a suction device (7c) with its inlet facing upward, and the duct for the extraction of sedimentary water is connected at one end to a suction device (8c) with its inlet facing the bottom of the tank or container, the hydrocarbon suction device is immersed in the hydrocarbons heated by the surrounding conduit, and the water suction device is positioned at the bottom of the tank (1) with its inlet slightly separated from the bottom, the operation The method according to claim 10, further comprising: <Claim 12> The method according to claim 11, wherein the high-temperature gas circulating through the surrounding conduit (5) is supplied by a second steam ejector (6), the gas discharge opening (6b) of which is connected to an inlet opening for the high-temperature gas in the surrounding conduit (5), the drive steam nozzle of which is connected to the steam boiler (4), and the gas intake opening of which draws in air from the atmosphere by the Venturi effect, thereby homogeneously mixing the drawn air with the drive steam and injecting it into the inlet opening for the gas in the surrounding conduit (5) by the second steam ejector (6) itself. <Claim 13> The method according to any one of claims 10 to 12, applicable to hydrocarbons having a flash point of 55°C or higher. <Claim 14> It is applicable to Class B hydrocarbons with a flash point below 55°C, and furthermore, - An operation to inject nitrogen from the tank (9) into the tank or container (1) until the oxygen concentration reaches less than 8%, - Operation of a controlled supply of nitrogen to maintain the oxygen concentration in the tank or container at all times below 8% The method according to any one of claims 10 to 12, further comprising:

Claims

1. A system for extracting viscous hydrocarbons from storage tanks and other containers, - A steam boiler (4) having control means configured to adjust the amount and temperature of the steam it supplies, wherein the temperature of the supplied water is between 120 and 200°C, - An apparatus for homogenizing the steam supplied by the steam boiler with a gas flow configured to recirculate gas from the steam boiler itself, injecting the resulting homogeneous gas mixture into the tank or container (1), and heating the surface layer of the extracted hydrocarbon, - At least one first pump (7) for selectively extracting the hydrocarbons from the surface layer heated by an injected homogeneous gas mixture, wherein the first pump (7) has a first pump suction duct (7a) connected in a peripheral region to the tank or container (1) for extracting the heated hydrocarbons from the surface layer therein. It has, The apparatus for homogenizing the gas flow and injecting it into the tank or container (1) comprises at least one steam ejector (3) arranged to provide vortex diffusion of the driving steam supplied by the steam boiler (4) and the recirculated gas from the tank or container (1), wherein the steam ejector (3) - The driving steam connected to the steam boiler (4), - A vapor ejector gas intake duct (3a) connected to a point in the tank or container (1) on the surface layer of the hydrocarbon to be extracted, - A steam ejector gas discharge duct (3b) through which the homogeneous gas mixture is injected into the tank or container (1). The diffuser of the steam ejector (3) has a vortex diffusion that occurs in the diffuser of the steam ejector (3) of the driving steam supplied by the steam boiler (4) and the gas that the steam ejector (3) draws in through the steam ejector gas intake duct (3a) by the Venturi effect, gas arriving from the tank or container (1) itself, from the atmosphere, from the steam boiler (4), or a combination thereof, and at the discharge port of the steam ejector gas discharge duct (3b) of the steam ejector (3), the homogeneous mixture of high-temperature gas obtained as a result of the vortex diffusion is injected into the tank or container (1) to heat the surface layer of hydrocarbons. As a result, such vortex diffusion prevents the steam injected into the tank or container (1) from moving freely upward, and consequently, most of the injected driving steam condenses on the surface layer of the hydrocarbon, and its latent heat is transferred to the surface layer. A system characterized by the following features.

2. - A peripheral conduit (5) externally attached to a portion of the metal wall of the tank or container (1) located below a level determined by the hydrocarbon being extracted, for the purpose of localized heating of the hydrocarbon, wherein a portion of the peripheral conduit (5) is made up of the portion of the metal wall of the tank or container (1) to which it is attached, and the high-temperature gas circulating through the peripheral conduit (5) comes into direct contact with the portion of the metal wall, thereby locally heating the hydrocarbon adjacent to the tank or container (1), - At least one second pump (8) for extracting sediment from the tank or container (1), wherein the first pump suction duct (7a) and the second pump suction duct (8a) are connected to the tank or container (1) in a peripheral region close to the region heated by the peripheral conduit (5), - A gas duct connected to the gas intake and discharge openings of the vapor ejector (3) and connected to two different points around the tank or container (1) located above a level determined by the hydrocarbons being extracted, wherein at least one of the two different points of the gas duct of the ejector is in close proximity to the surrounding area. The system according to claim 1, further comprising:

3. The system according to claim 2, wherein the first pump suction duct (7a) is connected at one end to an oil suction device (7c) with its suction opening directed upward, and the second pump suction duct (8a) is connected at one end to a sediment water suction device (8c) with its suction opening directed toward the bottom of the tank or container.

4. The system according to claim 2, wherein the surrounding conduit (5) consists of a synthetic fiber cover supported by semicircular arches distributed along the entire length of the surrounding conduit (5), thereby obtaining a semi-cylindrical shape having a flat portion that matches the portion of the metal wall of the tank or container (1) to which it is attached and sealed by two straps, and the semicircular arches have support plates at their two ends having rings welded to them for guiding and holding the two straps passing through them.

5. The system according to claim 4, wherein the hot gas circulating through the surrounding conduit (5) is supplied by a second steam ejector (6), the gas discharge opening of which is connected to an inlet opening for the hot gas in the surrounding conduit (5), the drive steam nozzle of which is connected to the steam boiler (4), and the gas intake opening of which draws in air from the atmosphere by the Venturi effect, thereby homogeneously mixing the intake air with the drive steam and injecting it into the inlet opening for the hot gas in the surrounding conduit (5) by the second steam ejector (6) itself.

6. The system according to claim 1, wherein the steam ejector gas intake duct (3a) has within it at least one gas circulator configured to increase the flow rate of gas that the steam ejector (3) injects into the tank or container (1).

7. The system according to claim 1, wherein the steam ejector gas intake duct (3a) has in it at least another steam ejector or a connection point for injecting depressurized steam.

8. The system according to any one of claims 1 to 7, configured to process hydrocarbons having a flash point of 55°C or higher, which are Class C and Class D hydrocarbons.

9. It is configured to process Class B hydrocarbons with a flash point below 55°C. The system according to any one of claims 1 to 7, wherein the vapor ejector gas intake duct (3a) for injecting the gas into the tank or container (1) is connected to a nitrogen tank having a control means configured to adjust the amount of nitrogen supplied.

10. A method for extracting viscous hydrocarbons from storage tanks and other containers, particularly tanks or containers (1) having a floating roof and metal walls, - A steam ejector (3) connected to a steam boiler (4) that supplies steam at a temperature of 120 to 200°C heats the surface layer of the hydrocarbon to be extracted. - The steam ejector (3) draws in gas arriving from the tank or container (1) itself, from the atmosphere, from the steam boiler (4), or a combination thereof, through its intake opening using the Venturi effect. - The steps of vortex-diffusing the aspirated gas with the driving steam supplied by the steam boiler (4), - A step of injecting the resulting homogeneous mixture of high-temperature gas into another point in the tank or container (1), - A step of adjusting the amount of steam supplied to the steam ejector (3) to create a selective flow of high-temperature hydrocarbons for selective extraction of hydrocarbons from the surface layer to the first pump suction duct (7a) of the first pump (7). A method that includes this.

11. - An operation in which a high-temperature gas circulates in a tank or container (1) through a peripheral conduit (5) externally attached to the tank or container (1) to locally heat the hydrocarbons selectively flowing from the surface layer, wherein during extraction, sedimentation of non-emulsified water occurs, and a selective flow of heated hydrocarbons is generated by the peripheral conduit (5) toward an oil suction device (7c) connected to a first pump (7) for selective extraction of hydrocarbons by a first pump suction duct (7a), and - The operation of selective extraction of hydrocarbons heated by the surrounding conduit (5) by the first pump (7), and periodic extraction of sediment by the second pump (8), wherein the first pump suction duct (7a) is connected at one end to an oil suction device (7c) with its suction port facing upward, and the second pump suction duct (8a) is connected at one end to a sediment suction device (8c) with its suction port facing the bottom of the tank or container (1), the operation The method according to claim 10, further comprising:

12. The method according to claim 11, wherein the high-temperature gas circulating through the surrounding conduit (5) is supplied by a second steam ejector (6), the gas discharge opening (6b) of which is connected to an inlet opening for the high-temperature gas in the surrounding conduit (5), the driving steam nozzle of which is connected to the steam boiler (4), and the gas suction opening of which draws in air from the atmosphere by the Venturi effect, thereby homogeneously mixing the drawn air with the driving steam and injecting it into the inlet opening for the gas in the surrounding conduit (5) by the second steam ejector (6) itself.

13. The method according to any one of claims 10 to 12, for use in processing Class C and Class D hydrocarbons having a flash point of 55°C or higher.

14. - The operation of initial nitrogen injection from the nitrogen tank (9) to the tank or container (1) until the oxygen concentration reaches less than 8%, - Operation of a controlled supply of nitrogen to maintain the oxygen concentration in the tank or container (1) at all times below 8% The method according to any one of claims 10 to 12, further comprising, for use in processing Class B hydrocarbons having a flash point of less than 55°C.

Images