• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A system and a procedure for the selective extraction of viscous hydrocarbons from tanks and other vessels is proposed. The system comprises the following hydrocarbon heating components: a steam ejector -3-, where there is a turbulent diffusion of its motor steam with the gases that it sucks in by Venturi effect, and a perimeter heating duct -5- attached externally to the tank or container. The process comprises the following operations: heating of a superficial layer of hydrocarbons by means of the gases injected by the steam ejector, which causes a selective flow of hot hydrocarbons towards the perimeter conduit; localized heating of the hydrocarbons with the perimeter conduit, which causes precipitation of the water and a selective flow of the hottest hydrocarbons to an extraction pump, and extraction by two pumps of the precipitated water and the hydrocarbons that flow selectively from the perimeter conduit . (Machine-translation by Google Translate, not legally binding)
    公开号:ES2796092A1
    申请号:ES202030521
    申请日:2020-06-03
    公开日:2020-11-25
    发明作者:Cuetos Evaristo Fontecha
    申请人:Cuetos Evaristo Fontecha；
    IPC主号:
    专利说明:

    [0002] SYSTEM AND PROCEDURE FOR THE SELECTIVE EXTRACTION OF VISCOSE HYDROCARBONS FROM TANKS AND OTHER VESSELS
    [0004] Technical field
    [0006] The present invention relates to a system and a process for the selective extraction of viscous hydrocarbons from storage tanks and other vessels, which must be emptied and cleaned regularly to carry out periodic inspections, repairs, load changes, demolitions, etc.
    [0008] The system and the method object of the invention are applicable to storage tanks and other containers containing viscous hydrocarbons existing in oil refineries, petrochemical plants, thermal power plants, port terminals, etc. Representative examples of applications of the invention are floating roof oil tanks and hydrocarbon process units, including distillation towers, reactors, air coolers, vessels with gaseous hydrocarbon demisters, interconnection pipes, etc.
    [0010] Among the viscous hydrocarbons to which the selective extraction system and procedure are applicable, it is worth highlighting the hydrocarbons that accumulate at the bottom of oil tanks (which are class B, flash point <55 ° C), the fuel oil (belonging to class C, flash point between 55 ° C and 100 ° C) and asphalt (which are class D, flash point> 100 ° C).
    [0012] Background of the invention
    [0014] US3874399A discloses a process for the evacuation of high viscosity hydrocarbons from a tank by recirculation to the tank of previously heated evacuated hydrocarbons, in order to reduce the viscosity of the tank contents and facilitate their evacuation.
    [0015] ES417373A1 describes a process for purging flammable residues from a container that comprises passing a gaseous stream containing water vapor and an inert gas such as nitrogen through the container, wherein the gaseous stream introduced into the container has a content of water vapor in the range between 4 and 50% by volume and transmits enough heat to the container to reach a temperature of at least 50 ° C.
    [0017] US5085242A discloses a method and an apparatus for the removal of waste from storage tanks by localized heating of the tank with either steam, water or electrical energy, causing a flow of hydrocarbons towards the heating zone.
    [0019] GB2101475A describes a method for cleaning storage tanks by heating the sludge by putting it in contact with hot water (injection and recirculation of hot water), thus achieving a temperature of 70 ° C that allows the extraction of the residue thanks to the decrease in viscosity.
    [0021] ES2391183B1 (P201100464), by the same inventor as the present application, discloses a procedure for the selective extraction of high viscosity hydrocarbons using the following steps: application of risk preventive measures (for oil tanks with floating roof, a measure of the explosiveness inside the tank), heating of the tank contents by means of flexible coils slightly immersed in the hydrocarbons, and heating of the hydrocarbon surface layer by injecting hot air into the tank.
    [0023] ES2544575B1 (P201400060), also by the same inventor as the present application, discloses a procedure for the selective extraction of viscous hydrocarbons remaining in storage tanks. The operations it comprises are the following: measurement of the explosiveness inside the tank, heating of the hydrocarbons by means of devices located inside the tank and heating of the surface layer of hydrocarbons by injecting hot air. As an additional stage, after the extraction of hydrocarbons and maintaining the injection of hot air, hot water is injected over the remaining hydrocarbons to facilitate their subsequent extraction.
    [0025] Document WO2017118766A1 (P201600007), also by the same inventor as the present application, discloses a process for the extraction of viscous hydrocarbons in tanks by injecting into the tank a stream consisting of hot air and steam. For injection, a centrifugal or blower fan is used that passes the current through an electric heater with baffles that causes a turbulent regime. This achieves the heating of the air, the absorption of humidity by the air and the superheating of the water vapor, followed by the extraction of the hydrocarbons. Furthermore, by means of heating devices located in the immediate vicinity of the suction lines, additional heating of the hydrocarbons can be carried out.
    [0027] Document WO2019197690 (P201800095), by the same inventor as this application, describes a process for the extraction of viscous hydrocarbons from storage tanks and process equipment, which proposes to inject an inert gas into the tank or equipment until a concentration of oxygen to ensure a zero flammability range, and then inject into the tank or equipment a stream of homogenized gases through an irreversible process of turbulent diffusion, the stream being made up of recirculating gases from the tank or equipment itself and by the quantities of water vapor and inert gas that are required at all times to maintain the oxygen concentration at values that ensure a zero flammability range and to make the hydrocarbons flow in an amount equivalent to that required by an extraction pump suitable for use in potentially explosive atmospheres.
    [0029] The process of the present invention differs from the aforementioned previous procedures by using in combination a steam ejector and a perimeter heating duct attached to the outer wall of the tank, which allows the hydrocarbons of the surface layer to be heated and the hydrocarbons adjacent to the entire length of the perimeter duct locally, in order to cause, with the double heating, that the water does not precipitate. emulsified for its separate extraction of hydrocarbons and that two selective flows of hydrocarbons are established, one from the surface layer towards the heated zone for the entire extension of the perimeter conduit and the second from said heated zone through the perimeter conduit towards a device. suction device of a pump that selectively removes hydrocarbons.
    [0030] The two components that characterize the process object of the present invention, the steam ejector and the perimeter heating duct, are not used in any of the previous procedures and provide results that are not obtained with either of them or with their combinations. , since it is not possible to generate two selective hydrocarbon fluxes from the surface layer nor the precipitation and separate extraction of the non-emulsified water.
    [0032] Therefore, with the process of the present invention, it is achieved that the extraction is more selective than with any of the previous processes or a combination thereof. The extraction of hydrocarbons is called "selective" because it meets two conditions: that the hydrocarbons are extracted separately from the non-emulsified water and that during the extraction the mixture of the hydrocarbons of the surface layer with the hydrocarbons closest to the bottom of the tank or container, which are those that are usually emulsified with water or contaminated by sludge and sediment.
    [0034] In the case of the antecedent procedures that are based on the generalized heating of the hydrocarbons in the tank, such as the US3874399A procedure, the extraction that is carried out is not selective as there is a generalized reduction in the viscosity of the hydrocarbons and consequently a unwanted flow of contaminated hydrocarbons from the bottom of the tank into the suction line of the pump.
    [0035] As for the antecedent procedures based on heating the limestone of the hydrocarbons in the tank, such as US5085242A, they are much less effective since the flow of hydrocarbons towards the heating zone becomes very slow or non-existent, in addition to producing a unwanted flow towards the heating zone of the most polluted hydrocarbons at the bottom of the tank, so the extraction is no longer selective.
    [0037] In the case of antecedent procedures that establish heating by injecting water vapor, such as ES417373A1, or that establish recirculation of hot water, such as GB2101475A, the extraction is not selective in any case, since a undesired flow towards the extraction zone of the most contaminated hydrocarbons from the bottom of the tank and the hydrocarbons are contaminated with water by the injected steam condensates or by recirculating hot water.
    [0039] When the procedure is applied to fuel oil tanks, avoiding both water contamination and the unwanted flow of contaminated hydrocarbons from the bottom of the tank is essential so that the extracted fuel oil can be marketed in compliance with legal specifications for water content and sediments. , since a small flow of contaminated fuel oil from the bottom of the tank towards the suction line of the pump is usually sufficient so that these legal specifications are not met and that all the extracted fuel oil has to be managed as waste.
    [0041] As for the other four background procedures referred to above (ES2391183B1, ES2544575B1, WO2017118766A1 and WO2019197690), the four correspond to the same inventor as the present application. In the last two (WO2017118766A1 and WO2019197690) the surface layer of the hydrocarbons is heated with steam, which is very effective due to the high heat transmission capacity of the water vapor, but the extraction is not selective because the hydrocarbons are contaminated with the condensates of the water vapor injected into the tank or container. For this reason, neither in the title nor in the reports of the procedures WO2017118766A1 and WO2019197690 mentions that the extraction of hydrocarbons is selective. On the contrary, the term "selective" does appear in the title and in the memorandum of the present invention, as in the first and second antecedent procedures (ES2391183B1 and ES2544575B1), these last procedures that establish the injection of hot air to heat the surface layer of hydrocarbons, so that the polluting effect of water vapor does not occur, but they have the drawbacks of having much lower heating capacity of the surface layer of hydrocarbons and having much higher investment costs in equipment and procedure execution.
    [0043] In relation to the aforementioned costs, the equipment that characterizes the system of the present invention is very simple and only requires the supply of steam for its operation. This advantage becomes even more apparent if it is taken into account that there is usually free availability of water flow in viscous hydrocarbon storage facilities. On the other hand, the four antecedent procedures of the same inventor referred to above require the use of a good number of electrical equipment: ATEX electric heaters, centrifugal fans, blowers, high-power generators, frequency variators, electrical panels, etc. On the contrary, the steam ejector and the perimeter duct are very low cost equipment that does not require maintenance due to the lack of mechanical or electrical components; Furthermore, the steam ejector alone performs multiple functions: suck gases from a point in the tank or container by Venturi effect, subject the gases aspirated to a turbulent diffusion process with its motor steam and inject the resulting homogeneous mixture of hot gases at another point in the same tank or container.
    [0045] In addition to performing the selective extraction with much greater heating capacity and at a much lower cost than the only two antecedent procedures that make it possible to perform it (ES2391183B1 and ES2544575B1), the procedure of the present invention allows a more effective selective extraction to be carried out. The significant reduction in viscosity experienced by Hydrocarbons with double heating (heating of the surface layer with the steam engine of the ejector and localized heating of the hydrocarbons adjacent to the entire length of the perimeter conduit) prevents the undesired flow of the most contaminated hydrocarbons and close to the bottom of the tank, which, as they are not heated, remain viscous and practically static. On the other hand, using either of the two aforementioned antecedent procedures, the hydrocarbons flow more viscous towards the suction device of the pump and the unwanted flow of hydrocarbons from the bottom of the tank towards the suction device of the pump occurs to some extent, especially as the level of hydrocarbons in the tank decreases and at times of the year (winter in the northern hemisphere) when the hydrocarbons closest to the bottom of the tank have a higher temperature than those on the surface.
    [0047] On the other hand, it should be mentioned that the procedures most used in refineries to extract viscous hydrocarbons from oil tanks are based on dilution with crude oil or low-viscosity hydrocarbons supplied by the refineries themselves. The process of the present invention has important advantages over said processes, by allowing the extraction of the hydrocarbons without mixing them with the contaminants at the bottom of the tanks, avoiding dangerous leaks inherent in said procedures in tanks with leaky bottoms and detaching the layer. of hydrocarbons that contaminates the walls and the internal face of the floating roof of the tank as an added cleaning effect. Furthermore, applying the procedure object of the invention requires the use of much simpler equipment that greatly reduces the investment costs in equipment and the execution costs. As regards other containers, the most widespread procedures are pressure water cleaning and chemical cleaning, compared to which the present procedure has the advantages of being more effective and generating less waste.
    [0048] Presentation of the invention
    [0050] The present invention relates to an extraction system and method selective selection of viscous hydrocarbons from storage tanks and other vessels. The extraction of hydrocarbons is called "selective" because it meets two conditions: that the hydrocarbons are extracted separately from the non-emulsified water and that during the extraction the mixing of the hydrocarbons of the surface layer with the hydrocarbons closest to the bottom of the tank or container, which are those that are usually emulsified with water or contaminated by sludge and sediment.
    [0052] The system for the selective extraction of viscous hydrocarbons from a storage tank or a container is characterized by comprising in combination, according to a first embodiment, the following components:
    [0054] - a steam boiler that has control means configured to regulate the quantity and temperature of the water vapor it supplies, the temperature being between 120 and 200 ° C (approximately between 2 and 15 bars);
    [0056] - at least one steam ejector intended to heat a surface layer of the hydrocarbons to be extracted, with its engine steam nozzle connected to said boiler, so that a turbulent diffusion of engine steam occurs in the steam ejector diffuser supplied by the boiler with the gases that the ejector sucks through its intake venturi effect, gases that come from the tank or container itself, from the atmosphere, from the steam boiler (water vapor to increase the temperature of the gases discharged by the ejector) or a combination of said sources, resulting in a homogeneous mixture of hot gases in the discharge mouth of the ejector that the steam ejector itself injects into the tank or container through a conduit of discharge of gases to heat the surface layer of hydrocarbons, and
    [0058] - at least one pump designed to selectively extract the hydrocarbons from the surface layer that heats the homogeneous mixture of hot gases injected by said steam ejector, a suction line of said pump being connected to the tank or container in a zone peripheral to which the hydrocarbons of the surface layer heated with the gases injected by the steam ejector flow.
    [0060] In the event that the boiler supplies water vapor to the ejector gas suction conduit to increase the temperature of the gases that are injected into the tank or container, said water vapor must be depressurized so as not to compromise the good operation of the ejector and not cause risks due to overpressures. The risks of overpressure can be eliminated by using a pressure reducing valve at the boiler outlet, a pipe with a diameter sufficient for the expansion of the water vapor or by means of a second steam ejector with its gas discharge mouth. connected to the gas suction port of the ejector that injects the gases into the tank or container.
    [0062] It should be noted from the system that the homogeneous mixture of gases resulting from the turbulent diffusion makes the free upward movement of the water vapor injected into the tank or container impossible, so that a large part of the injected engine vapor condenses on the surface layer of the hydrocarbons and It transmits large amounts of latent heat (539.4 cal / g at 100 ° C).
    [0064] According to another embodiment of the invention, the system further comprises:
    [0066] - at least one perimeter conduit for localized heating of the hydrocarbons, externally attached to a section of the metal wall of the tank or container located below the level determined by the hydrocarbons to be extracted, a part of the perimeter conduit being constituted by itself section of the metal wall of the tank or container to which it is attached, so that the hot gases that have circulated through the aforementioned perimeter conduit are in direct contact with said section of the metal wall and heat the hydrocarbons locally. adjacent areas of the tank or container, heat transmission that is a function of the area of the metal wall in contact with the hot gases, the temperature of the gases circulating through the perimeter conduit and the thermal conductivity of the metal wall of the tank or container ; - at least one second pump designed to extract the precipitated water in the tank or container, suction pipes of said first and second pumps being connected to the tank or container in a peripheral zone close to the zone heated by the perimeter conduit, and
    [0067] - Gas pipes connected to the gas suction and discharge ports of the ejector and to two different points on the periphery of the tank or container located above the level determined by the hydrocarbons to be extracted, at least one of said points being connection of the steam ejector pipes near the peripheral connection area of the hydrocarbon suction pipes and the precipitated water.
    [0069] In another embodiment, the invention additionally comprises:
    [0071] - a first suction device that is connected to one end of said hydrocarbon suction line and has its suction mouth facing upwards, and a second suction device that is connected to the precipitated water suction line and has its suction mouth oriented towards the bottom of the tank or container;
    [0073] - a perimeter heating duct made up of a synthetic fabric cover supported by semicircular arches that are distributed along the entire duct, so that the perimeter duct acquires a semi-cylindrical shape with its flat section coinciding with the wall section metal of the tank or container to which it is attached and sealed by means of two straps, said semicircular arches having support plates at their two ends that are welded with rings to guide and hold the two straps that cross them, so that by tightening the two straps at their ends to two anchor points, press and seal against the cylindrical wall of the tank or container the aforementioned support plates of all the arches and the upper and lower edges of the synthetic fabric along the entire length of the duct perimeter (for example, as a synthetic fabric, a roll of silicone fabric can be used that supports temperatures above 200 ° C and with approximate dimensions of 50 meters in length and 1 meter in width);
    [0075] - a steam ejector with its discharge mouth connected by means of a gas conduit to an inlet mouth of hot gases of the aforementioned perimeter duct, with its motor steam nozzle connected to the referred boiler and with its intake mouth of gases sucking by Venturi effect air from the atmosphere, so that the sucked air is homogeneously mixed with the motor steam and injected by the ejector itself into the hot gas inlet mouth of the perimeter duct;
    [0077] - at least one centrifugal fan or a blower installed in the gas suction line of the steam ejector and configured to increase the flow rate of gases that are injected into the tank or container;
    [0079] - at least one steam ejector or a connection point for the injection of depressurized water vapor installed in the gas suction line of the steam ejector that injects the gases into the tank or container to increase the temperature of the gases that are injected into the tank or container, and
    [0081] - a nitrogen tank connected to the gas suction line of the steam ejector that injects the gases into the tank or container to avoid the risk of fire or explosion in the case of hydrocarbons with a flash point below 55 ° C (class B), having control means configured to regulate the amount of nitrogen supplied to the tank or container.
    [0083] Likewise, the invention is applicable to the selective extraction of viscous hydrocarbons and other substances, being able to cite as a non-limiting example, asphalt emulsions, oily emulsions, oily sludge and soot, where the aforementioned hydrocarbons and substances, when subjected to some conditions of circulation of gases and heating, are capable of flowing towards a peripheral zone of the tank or container in which the connections are connected. ductions of at least one extraction pump.
    [0085] For its part, the procedure for the selective extraction of viscous hydrocarbons from storage tanks and other containers that is the object of the present invention is characterized by the following operations:
    [0087] - heating of a superficial layer of the hydrocarbons to be extracted by means of a steam ejector connected to a boiler that supplies steam at a temperature between 120 and 200 ° C, so that said ejector sucks gases from a point of the tank or container, subjects the aspirated gases to a turbulent diffusion with its motor steam and injects the resulting homogeneous mixture of hot gases at another point in the same tank or container, the ejector gas aspiration and discharge points being above the level determined by the hydrocarbons to be extracted, and regulating the amount of steam that is supplied to the ejector so that during the extraction a selective flow of hot hydrocarbons is established from the surface layer towards a zone of localized heating of the hydrocarbons in a amount equivalent to that drawn in by a pump that selectively extracts hydrocarbons;
    [0089] - localized heating of the hydrocarbons that flow from the surface layer through a perimeter conduit externally attached to a tank or container through which hot gases are circulated, so that during the extraction there is a precipitation of the non-emulsified water and a selective flow of the heated hydrocarbons through the perimeter conduit towards a suction device that is connected by a pipeline to a pump for the selective extraction of the hydrocarbons, and
    [0091] - Selective extraction of the hydrocarbons that heats the perimeter conduit with a first pump and periodic extraction of the precipitated water with a second pump, where the conduction for the extraction of the hydrocarbons has a suction device connected at one end with its upward-facing suction and conduction for ex traction of the precipitated water has a suction device connected at one end with its suction mouth oriented towards the bottom of the tank or container, the hydrocarbon suction device being immersed in the hydrocarbons heated by said perimeter conduit and the device for water suction positioned at the bottom of the tank, with its suction mouth slightly separated from the bottom.
    [0093] Once the heat input is no longer effective and the hydrocarbon flow to the pump suction device ends, the extraction is considered complete and the interior of the tank or container is inspected. If significant amounts of hydrocarbons remain in any area of the tank or container, the extraction would continue, conveniently choosing the installation points of the aforementioned equipment that define the system of this invention. At the end of the extraction of the hydrocarbons, water, oily sediments or hydrocarbons with a high melting temperature remain at the bottom of the tank or container, which are removed by conventional methods. On the other hand, it is noteworthy that when applying the procedure it is possible to eliminate the hydrocarbon layer initially adhered to the walls and the internal face of the roof of the tank, which is released by the circulation of hot gases inside the tank or container and especially due to the heating and drag of the water vapor as it condenses on the hydrocarbon layer.
    [0095] It should be noted from the procedure that the homogeneous mixture of the gases caused by the turbulent diffusion in the steam ejector diffuser makes the free upward movement of the water vapor injected into the tank or container impossible, so that a large part of the injected engine steam it condenses on the surface layer of hydrocarbons and transmits large amounts of latent heat to it (539.4 cal / g at 100 ° C).
    [0097] In another embodiment of the invention, the hot gases that have circulated through the perimeter heating duct are supplied by a steam ejector with its gas discharge mouth connected to a hot gas inlet mouth of the perimeter duct, with its steam nozzle motor connected to the aforementioned boiler and with its gas suction mouth sucking air from the atmosphere by Venturi effect, so that the sucked air is homogeneously mixed with the motor steam and injected by the ejector itself into said inlet mouth of perimeter duct gases.
    [0099] In the event that the tank or container contains viscous hydrocarbons whose flash point is below 55 ° C (class B), the following operations are also included:
    [0101] - initial injection of nitrogen into the tank or container to achieve oxygen concentrations below 8%, and
    [0103] - regulated supply of a quantity of nitrogen in said steam ejector suction duct to keep the oxygen concentration in the tank or container below 8% at all times. Injecting steam into the tank or vessel also helps to keep the oxidizing oxygen concentration below 8% (the constituent oxygen in water vapor is not oxidizing).
    [0105] As indicated above, when the system and procedure are applied to the selective extraction of class B viscous hydrocarbons (flash point <55 ° C), such as those that accumulate at the bottom of oil tanks, must inject nitrogen into tanks or vessels to keep the oxygen concentration inside them below 8% at all times, while in the case of viscous hydrocarbons of classes C and D (flash point> 55 ° C), such as For fuel oil and asphalt, it is not necessary to inject nitrogen into the tank or container because there are no risks of fire and explosion applying the system and procedure object of the invention.
    [0106] The system and the method object of the invention are applicable to storage tanks and other containers containing viscous hydrocarbons existing in oil refineries, petrochemical plants, thermal power plants, port terminals, etc. As for the way of applying the invention to other containers, it is practically the same as in storage tanks. with the exception of having to adapt in each case the installation of the equipment to its multiple configurations and sizes. Examples of these latter applications are the process units of refineries and petrochemical plants, which include distillation towers, reactors, air coolers, vessels with gaseous hydrocarbon demisters, interconnection pipes, etc. Both the system and the procedure can be applied to complete process units or separately to their components, conveniently choosing in both cases the gas suction and discharge points of one or more steam ejectors and the heating zones. localization of hydrocarbons, and injecting nitrogen as a measure to prevent fire and explosion risks.
    [0108] Brief description of the drawings
    [0110] Figure 1 shows a floating roof oil tank -1- in whose manholes are installed some covers -2a- and -2b- that have connection fittings necessary to install the system and apply the procedure . A steam ejector -3- sucks gases from a point of the tank by Venturi effect through a gas suction pipe -3a- connected to the cover -2a- and, through a gas discharge pipe -3b- connected to the lid -2b-, injects them hot and homogeneously mixed with the motor steam supplied by a steam boiler -4- at a temperature between 120 and 200 ° C, the boiler having a valve -4a- to regulate the quantity of water vapor that supplies the ejector.
    [0112] On the other hand, a perimeter conduit -5- is installed attached to the outer metal wall of the tank to heat the oil adjacent to the entire length of the perimeter conduit. In an embodiment of the invention, the perimeter duct is connected to a second steam ejector -6-, which sucks air from the atmosphere -6a- by Venturi effect and discharges it into the perimeter duct, through the duct discharge gas -6b-, homogeneously mixed with the motor steam supplied by the steam boiler -4-, which has a regulation valve -4b-.
    [0113] A pump -7- selectively extracts the oil that heats the perimeter duct through a suction line -7a-, and a second pump -8- extracts the precipitated water through a suction line -8a-. The extracted oil and water are pumped separately, through oil and water impulsion lines -7b- and -8b-, to certain storage, transport or treatment points to be determined. The aforementioned pump suction lines are connected at their respective ends to devices for suction of oil -7 c- and for suction of precipitated water -8c-, devices that are positioned inside the tank next to the area heated by the perimeter conduit and which are designed so that the oil suction device has its suction mouth facing upwards and the water suction device has its suction mouth facing the bottom of the tank and slightly separated from it.
    [0115] Since the hydrocarbons that accumulate at the bottom of the oil tanks are class B (flash point <55 ° C), to eliminate the risks of fire and explosion, a nitrogen tank -9- has been planned which, By means of a control valve -9a-, it supplies a regulated quantity of nitrogen to the gas suction line of the ejector -3a-. In this way, the flow of hot and homogenized gases that are injected into the tank has a high concentration of nitrogen that contributes to maintaining an oxygen concentration below 8% inside the tank at all times. Furthermore, the injection of motor steam from the ejector also helps to keep the concentration of oxidizing oxygen in the tank below 8% (the oxygen constituting water vapor is not oxidizing).
    [0117] Detailed description of a preferred application example of the invention
    [0118] An example of a preferred application of the procedure is represented by the extraction of viscous hydrocarbons that accumulate at the bottom of oil floating roof tanks (class B hydrocarbons, with a flash point <55 ° C).
    [0120] The sequence of operations of the procedure is as follows:
    [0121] - initial injection of nitrogen into the tank until an oxygen concentration of less than 8% is achieved. Later, during oil extraction, a nitrogen tank -9-, fitted with a control valve -9a-, supplies a regulated quantity of nitrogen, so that an oxygen concentration is maintained inside the tank at all times. below 8%;
    [0123] - Heating of a superficial layer of oil by means of a steam ejector -3- that sucks gases from a point of the tank itself above the level of the oil to be extracted and returns them homogeneously mixed with its motor steam and the amount of nitrogen that is Required to keep the oxygen concentration below 8%. The amount of motor steam that is supplied to the ejector is regulated so that an amount of oil from the surface layer that is sufficient not to slow down the selective extraction of oil flows selectively towards an area adjacent to a perimeter heating duct -5- ;
    [0125] - Localized heating of the oil with the aforementioned perimeter conduit externally attached to the tank, so that as the viscosity of the adjacent hydrocarbons decreases with heating, the non-emulsified water precipitates and a selective flow of the oil heated by the perimeter conduit to a suction device -7 c- connected to an oil extraction pump -7-. The injection of hot gases into the perimeter duct is carried out using a second steam ejector -6- that sucks air from the atmosphere by Venturi effect and injects it into the perimeter duct homogeneously mixed with its motor steam, water vapor that is supplied by said steam boiler -4-, which regulates said supply through valve -4b-, and
    [0127] - Selective extraction of oil that heats the perimeter conduit and separate extraction of the precipitated water with two pumps -7- and -8-, whose respective suction devices -7c- and -8c- are located inside the tank next to the zone heated by the perimeter duct. In this way, The pumps allow the oil and water to be transferred separately to the points designated for their storage, transport or treatment.
    [0128] Once the heat input is no longer effective and the oil flow to the oil suction device -7 c- ends, the extraction is considered complete and the interior of the tank is inspected. If significant amounts of oil remain in any area of the tank, the extraction will continue, suitably choosing the equipment positioning points. In large tanks, various positioning of the equipment can be carried out or two or more steam ejectors can be used simultaneously with their corresponding perimeter heating ducts and extraction pumps. At the end of the oil extraction, water, oily sediments or hydrocarbons with a high melting temperature always remain at the bottom of the tank, which are removed by conventional methods. On the contrary, it is noteworthy that by applying the procedure it is possible to eliminate the oil layer initially adhered to the walls and the internal face of the tank roof, which is released by the circulation of hot gases inside the tank and especially by the heating and entrainment of water vapor as it condenses on the oil layer.
    权利要求:
    Claims (14)
    [1]
    1. - System for the selective extraction of viscous hydrocarbons from storage tanks and other containers, comprising:
    - a steam boiler that has control means configured to regulate the quantity and temperature of the water vapor it supplies, the temperature being between 120 and 200 ° C;
    - at least one steam ejector intended to heat a surface layer of the hydrocarbons to be extracted, with its engine steam nozzle connected to said boiler, so that a turbulent diffusion of engine steam occurs in the steam ejector diffuser supplied by the boiler with the gases that the ejector sucks by Venturi effect through its intake, gases that come from the tank or container itself, from the atmosphere, from the steam boiler or from a combination of these sources, resulting in a homogeneous mixture of hot gases that the steam ejector itself injects into the tank or container through a gas discharge line to heat the surface layer of hydrocarbons, and
    - at least one pump designed to selectively extract the hydrocarbons from the surface layer that heats the homogeneous mixture of hot gases injected by said steam ejector, a suction line of said pump being connected to the tank or container in a peripheral zone towards the one that flows the hydrocarbons of the surface layer heated with the gases injected by the steam ejector.
    [2]
    2. - System according to claim 1, wherein it further comprises:
    - at least one perimeter conduit for localized heating of the hydrocarbons, externally attached to a section of the metal wall of the tank or container located below the level determined by the hydrocarbons to be extracted, a part of the perimeter conduit being constituted by the section of the metal wall of the tank or container to which it is attached, so that the hot gases that have circulated through said perimeter conduit are in direct contact with said section of metal wall and heat located the adjacent hydrocarbons of the tank or container;
    - at least one second pump designed to extract the precipitated water in the tank or container, suction pipes of said first and second pumps being connected to the tank or container in a peripheral zone close to the zone heated by the perimeter conduit, and
    - Gas pipes connected to the gas suction and discharge ports of the steam ejector and to two different points on the periphery of the tank or container located above the level determined by the hydrocarbons to be extracted, at least one of said points being connection of the ejector pipes close to said peripheral connection area of the hydrocarbon suction pipes and precipitated water.
    [3]
    3. - System according to claim 2, wherein said hydrocarbon suction conduit is connected at one end with a suction device with its suction mouth facing upwards and the precipitated water suction conduit is connected at one end with a suction device with its suction mouth directed towards the bottom of the tank or container.
    [4]
    4. - System according to claims 2 and 3, wherein the perimeter heating duct consists of a synthetic fabric cover supported by semicircular arches that are distributed along the entire duct, so that the perimeter duct acquires a semi-cylindrical shape with its flat section coinciding with the metal wall section of the tank or container to which it is attached and sealed by means of two straps, with the aforementioned semi-circular arches at both ends of support plates that are welded with guide rings and fastening of the two straps that cross them, so that when the two straps are tightened at their ends to Two anchor points press and seal against the cylindrical wall of the tank or container the support plates of all the arches and the upper and lower edges of the synthetic fabric along the entire length of the perimeter conduit.
    [5]
    5.
    [6]
    6. - System according to the preceding claims, wherein the gas suction conduit of the steam ejector has installed at least one centrifugal fan or a blower configured to increase the flow of gases that the steam ejector injects into the tank or container.
    [7]
    7. - System according to claims 1 to 6, wherein the gas suction conduit of the steam ejector has installed at least a second steam ejector or a connection point to inject desurized steam in order to increase the temperature of the gases that are injected into the tank or container.
    [8]
    8. - System according to claims 1 to 7, wherein the flash point of the hydrocarbons is equal to or greater than 55 ° C, classes C and D.
    [9]
    9. - System according to claims 1 to 7, applicable to hydrocarbons whose flash point is less than 55 ° C, class B, where the gas suction conduit of the steam ejector that injects the gases into the tank or container is connected to a nitrogen tank that has control means configured to regulate the amount of nitrogen supplied.
    [10]
    10. - System according to the preceding claims, applicable to the selective extraction of viscous hydrocarbons and other substances, comprising emul Asphalt sions, oily emulsions, oily sludge and soot, where the aforementioned hydrocarbons and substances, when subjected to conditions of gas circulation and heating, are capable of flowing towards a peripheral zone of the tank or container in which they are connected. the lines of at least one extraction pump.
    [11]
    11.- Procedure for the selective extraction of viscous hydrocarbons from storage tanks and other containers, in particular from a tank with a floating roof and metal wall, which includes the following operations:
    - heating of a superficial layer of the hydrocarbons to be extracted by means of a steam ejector connected to a boiler that supplies steam at a temperature between 120 and 200 ° C, so that said ejector sucks gases from a point of the tank or container, subjects the aspirated gases to a turbulent diffusion with its motor steam and injects the resulting homogeneous mixture of hot gases at another point in the same tank or container, regulating the amount of steam that is supplied to the ejector so that during the extraction a selective flow of hot hydrocarbons is established from the surface layer towards a zone of localized heating of the hydrocarbons in an amount equivalent to that drawn by a pump that selectively extracts the hydrocarbons;
    - localized heating of the hydrocarbons that flow selectively from the surface layer through a perimeter conduit externally attached to the tank or container through which hot gases are circulated, so that during the extraction, non-emulsified water precipitates and is establishes a selective flow of the heated hydrocarbons through the perimeter conduit towards a suction device that is connected by a pipeline to a pump for the selective extraction of the hydrocarbons, and
    - Selective extraction of the hydrocarbons that heats the perimeter conduit with a first pump and periodic extraction of the precipitated water with a second pump, where the conduction for the extraction of The hydrocarbons has a suction device connected at one end with its suction mouth facing upwards and the conduction for the extraction of the precipitated water has a suction device connected at one end with its suction mouth facing the bottom of the tank or container, the hydrocarbon suction device being immersed in the hydrocarbons heated by said perimeter conduit and the water suction device positioned at the bottom of the tank, with its suction mouth slightly separated from the bottom.
    [12]
    12. Method according to claim 11, wherein the hot gases that are circulated through said perimeter duct are supplied by a steam ejector with its gas discharge mouth connected to a hot gas inlet mouth of the perimeter duct , with its motor steam nozzle connected to said boiler and with its gas suction mouth sucking air from the atmosphere by Venturi effect, so that the sucked air is homogeneously mixed with the motor steam and injected by the ejector itself into said gas inlet mouth of the perimeter duct.
    [13]
    13. - Process according to claims 11 and 12, wherein the flash point of the hydrocarbons is equal to or greater than 55 ° C, classes C and D.
    [14]
    14. - Process according to claims 11 and 12, applicable to hydrocarbons whose flash point is less than 55 ° C, class B, which also includes the following operations:
    - initial injection of nitrogen into the tank or container until an oxygen concentration is below 8%, and
    - Regulated nitrogen supply to keep the oxygen concentration in the tank or container below 8% at all times.
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    同族专利:
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    ES2796092B2|2021-07-05|
    WO2021255304A1|2021-12-23|
    引用文献:
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    优先权:
    申请号 | 申请日 | 专利标题
    ES202030521A|ES2796092B2|2020-06-03|2020-06-03|SYSTEM AND PROCEDURE FOR THE SELECTIVE EXTRACTION OF VISCOSE HYDRO-CARBIDE FROM TANKS AND OTHER CONTAINERS|ES202030521A| ES2796092B2|2020-06-03|2020-06-03|SYSTEM AND PROCEDURE FOR THE SELECTIVE EXTRACTION OF VISCOSE HYDRO-CARBIDE FROM TANKS AND OTHER CONTAINERS|
    PCT/ES2021/070396| WO2021255304A1|2020-06-03|2021-06-02|System and method for the selective extraction of viscous hydrocarbons from tanks and other containers|
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