RU2775989C1 - System and method for cleanout of hydrocarbon storage tanks - Google Patents

Abstract

FIELD: hydrocarbon storage.

SUBSTANCE: invention relates to an automatic modular system and a method for cleaning hydrocarbon storage tanks. The hydrocarbon storage tank cleanout system is an automated modular system that includes: one or more programmable cleaning nozzles, made with the possibility of lifting and rotating movement by 360°, which have one or more nozzles with a cleaning range from 0 to 180°; injection and recirculation equipment, made with the possibility of supplying the required pressure and flow to cleaning nozzles designed for injecting chemical mixtures by means of an injection pump or compressor; oil waste separation and extraction equipment, made with the possibility of centrifugation of sludge from a hydrocarbon storage tank, and separation of solid particles; sludge extraction module, made with the possibility of recirculation at the bottom of the tank and dilution of all types of paraffins or unwanted compounds; chemical mixing tank and sludge receiving tank; and equipment made with the possibility of creating and injecting inert gas into the tank on a permanent basis.

EFFECT: increase in the degree of extraction of hydrocarbons from sediments.

7 cl, 2 dwg

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

The present invention relates to a modular system for cleaning hydrocarbon storage tanks, as well as a cleaning method that allows you to recover crude oil from spent sludge contained in hydrocarbon storage tanks. In addition, the present invention relates to the use of chemical mixtures used during the cleaning process of hydrocarbon storage tanks.

BACKGROUND OF THE INVENTION

Various systems and compositions are known in the art for cleaning tanks and remaining sludge. For example, US Pat. No. 7,594,996 discloses a process for recovering oil, comprising the steps of contacting a viscous oil product with a water-based dispersion fluid, negatively charged, slurry-forming fluid, and having solid impurities inside; and processing the fluid slurry to separate and recover oil, solid contaminants and dispersion fluid as separate products; wherein said contacting step comprises the steps of injecting a dispersive fluid into contact with the oil under relatively high pressure conditions to form a fluid slurry, passing the fluid slurry through the injection chamber, and injecting additional dispersive fluid contacting the slurry into said injection chamber under conditions of relatively high pressure and shear.

Similarly, US Pat. No. 5,421,903 discloses a process for flushing an oil reservoir and recovering and treating residual reservoir fluid, comprising the steps of:

load on the first means of transport the first unit of the system, equipped with a suction device for suction and discharge of residual liquid from the tank;

loading onto the second conveyance means the second unit of the system, equipped with an oil/water separator for separating the oil component from the residual liquid received from the first unit of the system, a device for treating the separated oil component, and a means for supplying a washing liquid to the tank;

load on the third means of transport the third unit of the system, equipped with an inert gas generator;

moving the first, second and third means of transport into the tank to be washed;

mutually connecting the first, second and third blocks of the system with a reservoir with a pipeline;

controlling the operation of the means for supplying the washing liquid to the reservoir for jet supplying the washing liquid to the reservoir;

control the operation of the suction device for suction and discharge of residual liquid from the tank;

controlling the operation of the oil/water separator to separate the oil component from the discharged residual liquid;

controlling the operation of the oil component of the processing device to process the separated oil component;

rinse the tank with hot water; and

supplying an inert gas to the reservoir during the above treatments.

On the other hand, US Application 20060142172 discloses a composition for removing wax, heavy asphaltene, oil and other soils from oil wells and refinery equipment, containing about 1-50% C10-C15 naphthalene depleted in a mixture of aromatic solvents, containing less than 1% naphthalene and less 50 ppm toluene with a flash point of about 100°, and up to 10-50% other additives.

Despite the existence of tank cleaning systems and tank cleaning compositions, no technology can recover a significant amount of hydrocarbons for reuse.

There are currently financial losses due to unrecovered crude oil being destroyed by thermal desorption (approximately 100% of the material is destroyed).

Moreover, in the cleaning methods and cleaning systems known so far, there is a high risk of poisoning due to the presence of gases, since the operator must enter the same tank; moreover, there are risks of explosions due to the type of equipment and tools used.

Thus, there is a need for automated systems that can recover a greater percentage of the hydrocarbons contained in the reservoir sediments.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide an automated modular hydrocarbon storage tank cleaning system that can be installed in any type of site. In a further embodiment, the system may be a semi-automated modular system.

Moreover, the present invention provides a system that can reduce cleaning time by more than 80% compared to current systems in the art.

Yet another object of the present invention is to provide a purification process comprising the use of chemical mixtures that act as purification and recovery products, respectively.

Another object of the present invention is to provide a purification method performed by the system of the present invention, which allows up to 90% recovery of hydrocarbons present in the waste.

The above is measured by, for example:

Waste properties

Water <1%

Solid waste <1%

API=13.0

Oils and paraffins: 30%

Yet another object of the invention is to provide a method and system that allows hydrocarbon storage tanks to be cleaned and recovered for reuse, thus complying with national and international environmental guidelines.

A further object of the invention is to reduce the final disposal of particulate matter to protect the environment from containment and destruction.

Brief description of the figures

Figure 1 is a diagram showing the installation and distribution of the system of the present invention according to the preferred embodiment.

Figure 2 is a diagram of the process steps and distribution of a hydrocarbon storage tank cleaning system in accordance with a preferred embodiment of the present invention.

Detailed description of the invention

Some aspects of the present invention will now be described in detail by additional reference to the attached drawings, which show the advantages of the present invention (but not limited to this). In fact, several embodiments of the invention may be expressed in many ways and should not be construed as limiting the embodiments described herein; these exemplary embodiments are provided so that the present invention is complete and complete, and will fully convey the scope of the invention to a person skilled in the art. For example, unless otherwise noted, anything described as first, second, or the like is not to be interpreted as a special order. As used in the description and additionally in the accompanying claims, singular forms contain plural references unless the context clearly indicates otherwise.

Various aspects of the present invention relate to a system and method for cleaning hydrocarbon storage tanks.

In a first aspect, the present invention discloses a mobile and modular automated cleaning system that allows hydrocarbon storage tanks to be cleaned without the need for personnel. Moreover, the system of the present invention is versatile and can be adapted to different types of tanks, according to their type and location. In a further embodiment, the system of the present invention may be a semi-automated system.

In a preferred embodiment, Figure 1 shows the system (1) of the present invention and its distribution, which contains one or more tank cleaning nozzles (2) from one or more nozzles, performing unique separate rotary and lifting movements, allowing fast self-programmed redefinition for sector cleaning . In another aspect, the nozzle nozzle has a cleaning range from 0 to 180°, while the nozzle is able to rotate 360°, covering the entire area to be cleaned and reducing flushing time. Moreover, personnel are prevented from being drawn into confined spaces for cleaning.

In another aspect, the nozzles (2) are programmable according to the type of cleaning, either during this step or before it.

In another aspect, the system (1) comprises injection and recirculation equipment (C2) mounted on a portable skid to supply the required pressure and flow to the cleaning nozzle(s) (2). The flow control is achieved by means of a valve contained in the suction pump, which is not shown.

The injection and recirculation equipment (C2) injects chemical mixtures by means of an injection pump or compressor (A1) on the vacuum side of the primary pumps. The entire slip is protected against pressure by a pressure relief valve on the discharge.

In a related aspect of the present invention, the system also includes oil waste separation and recovery equipment (not shown) that operates at least 50 hp. and a capacity of at least 3300 g. In a preferred embodiment, the separation and recovery equipment has a process capacity of approximately 10-20 m ³ /h.

In a preferred aspect, the oil waste separation and recovery equipment centrifuges the sludge coming from the storage tanks, reducing by the order of microns (according to density/solids/gallons per minute/ROP). The solids separated by such equipment have a range of at least 3 inches, and achieve a discharge of at least 1000 m horizontally, depending on the material received.

In a further aspect, the system (1) comprises a recovery module (C1) to achieve recirculation at the bottom of the storage tanks and hence dilute all types of paraffins or other undesirable compounds.

In a preferred embodiment, the system (1) of the present invention may comprise a chemical mixing tank (C3) and a sludge receiving tank (C4), which may also contain one tank (C3/C4) of different capacities according to treatment requirements.

In a further aspect, system (1) also includes equipment (N2) for generating an inert gas, preferably nitrogen (N ₂ ), whereby equipment (N2) injects the gas on a continuous basis. The injection is performed to reduce the oxygen concentration below at least 6%.

Equipment (N2) maintains a constant flow of at least 500 m ³ /h and pressure up to 300 psi.

Being modular, system (1) can be programmed by the operators themselves. This allows you to monitor the needs of the area, in cases where more pressure, flow or chemicals are needed to achieve the parameters described above. In addition, the present invention provides the ability to install a mobile laboratory (LAB) and have an eclectic generator (GE) ready to maintain the correct operation of the entire system.

In another aspect of the present invention, chemical mixtures (Q1) are used which provide recovery and purification respectively, and which are applicable in the system (1) of the present invention.

In one embodiment, the cleaning mixture may contain oil-soluble asphalt and a wax dispersant concentrate that disperses, breaks the molecular chains, and wets the solids contained in the layers of the reservoir to facilitate the recovery of wax and oil residues.

In a preferred embodiment, the cleaning mixture may contain a mixture of benzene derivatives, in particular it may contain a mixture of xylenes.

The following table shows a preferred embodiment of the cleaning mixture composition of the present invention:

Component % (volume content) xylene blend 30 - 70 Fraction C ₆ - C ₁₀ 30 - 50

In another aspect of the present invention, the recovery mixture contains a concentrate for quickly and safely treating heavy and viscous sludge in tank layers. Said recovery mixture reaches from about 89% to about 99% of the oil contained in the sludge/sludge contained in the reservoir. In addition, the mixture preferably contains a chemical that works by separating emulsions into three: oil fractions, water and solids, without the use of heat treatment, which is usually expensive and dangerous.

In one embodiment, the recovery mixture may contain benzene derivatives and other organic compounds.

In a preferred embodiment, the recovery mixture may contain xylenes and fatty acid esters.

The following table shows a preferred embodiment of the composition of the extract mixture of the present invention:

Component % (volume content) xylene blend 30 - 60 Fraction C ₆ - C ₁₀ 30 - 50 Epoxidized fatty acid esters 2 - 10

In another aspect of the present invention, a method for cleaning hydrocarbon storage tanks is provided, which is described by the diagram in Figure 2.

In this sense, the chemical mixtures of the present invention (for purification and recovery) are injected (A) into the hydrocarbon storage tank by the injection equipment and the recirculation equipment (C2). At the same time, recirculation (B) is achieved, preferably through the bottom of the tank, and suction of oil spills; and extraction (C) of the sludge by an extraction module (5) allowing any agglomerated product to be finely ground, causing it to be diluted. As the process continues, (D) a sludge receiver/chemical mixing tank (C3/C4) is supplied in which the various chemicals are mixed and returned (E) to the recovery module (C1) to recycle/relieve oil spills.

In one aspect of the method, the hydrocarbon storage tank is inert when the sludge begins to sink and a space is created between the dome and the layer of sludge contained in the tank.

The purpose of injecting an inert gas into the tank is to displace any oxygen that may have entered the space created between the silt layer and the dome. The inert gas injection will depend on the requirement required by the job.

Prior to nitrogen injection, surface sealing of the tank perimeter and dome supports is performed to reduce oxygen ingress and leakage of the inert gas to be injected.

In a preferred embodiment, the flow of inert gas to be injected will have a variable range from 150 to 350 m ³ /h, depending on the operation.

In the next step, sampling (F) of the obtained products is carried out. If conditions (G) are met, the products are passed to separation and recovery equipment (not shown) to produce crude oil and various solids. Otherwise, the products are returned (H) to the tank (C3/C4). Finally, the extracted products are returned to the container for reuse/commercialization. Moreover, when the dilution and removal of sludge from the interior of the hydrocarbon storage tank is completed, the nozzles are moved to cover a larger part of the tank during the activation step. This starts with water recirculation through injection and recirculation equipment (C2) that will be programmed to act on the walls, bottom and dome of the tank.

In a further embodiment, the method may comprise manually cleaning the hydrocarbon storage tank by removing all perimeter seals and supports of the hydrocarbon storage tank, a ventilation system (Venturi) may be placed to vent any possible gases created during the process.

A visual inspection of the inside of the tank will be performed after the tank has been vented. Small portions of solids that are trapped in the tank structures will be removed manually by the extraction module (C1), the waste of which will be thrown into the gondola for transportation and final disposal.

EXAMPLES

The examples described in detail below, in relation to the subject matter of the present invention, in no way limit the scope of this Application.

Example 1

TECHNOLOGICAL PROPOSAL FOR CLEANING THE TANK TV-5002 500,000 BARREL LOCATED IN THE DOS BOCAS MARITIME TERMINAL

Before installing the cleaning system, the sludge was measured to identify which sector and vacuum point is suitable to start the process.

During the installation of the cleaning system, ashtray type mats were installed to protect the floor in case of any spillage.

The process starts by vacuuming a 4" diameter oil spill, the sludge recovery module creates a 25 ftHg vacuum with 7 bar discharge, which allows all agglomerated products to be finely ground causing them to be dispersed, then injection of chemical mixtures from the bottom (oil spills) will be performed. , and nozzles for dissolving sludge located in the first sector of the tank. This breaks the van der Waals bonds in the molecular chains of fuel oil and paraffins, returning them to a liquid state.

Injection of chemical mixtures and injection of recycled sludge into the dome of the tank is achieved by nozzles suitable for operation in hazardous areas, which are capable of reaching an explosion with a radius of 25 to 30 m with a sludge destruction efficiency of 70 cm due to their design and in accordance with the operating conditions required in this field .

The design of the nozzles allows them to be installed on the supports (legs) of the tank dome, achieving different strategies for their location and better performance during the process.

The injection and recirculation system is responsible for the recycling of sludge and chemicals with a flow rate of 80 to 110 m ³ /h at a pressure of 8 to 15 bar.

During the cleaning process, two 70 m3 containers ^were used to store and mix the settled sludge and chemical mixtures. These containers served to maintain a constant and efficient recycling process.

The process area was demarcated and monitored by security personnel to ensure the safety of operating personnel.

During the recovery of the sludge and chemical mixtures, and the dilution and recycling process, a sample of the recycled product is taken for chemical saturation analysis, followed by chemical recovery from the hydrocarbons and, if necessary, physical separation.

During the dilute sludge recycling process, total solids and water analyzes were performed in the oil to determine the amount of solids, water and oil contained in the dilute sludge batch.

The mechanical separation was carried out by the separation and extraction equipment, by means of a horizontal centrifuge mounted on a stand, which has a separation capacity of 10 to 20 m ³ at about 3000 rpm, depending on the operating conditions.

The separated solid fraction of the mixture contained in the sludge was placed in gondolas for transportation and final disposal, having the necessary permits for such activities.

The liquid fraction (recovered crude oil) was delivered to PEMEX with pre-authorization from DIAVAZ to verify product quality.

The inertization of the tank was achieved by nitrogen generation equipment.

This stage of inertization of the tank occurs when the silt begins to sink and a space is created between the dome and the layer of silt contained in the tank.

The purpose of injecting an inert gas into the tank is to displace any oxygen that may have entered the space created between the silt layer and the dome.

The inert gas injection will depend on the demand required by the job.

Prior to nitrogen injection, the tank perimeter and dome supports were externally sealed to reduce oxygen entry and leakage of the inert gas to be injected.

The flow of inert gas to be injected varies from 150 to 350 m ³ /h, depending on the operation.

When the dilution and removal of silt from the interior of the tank is complete, the nozzles are moved to cover the majority of the tank during the activation phase.

Then, water recirculation was initiated by means of nozzles that were programmed to act on the walls, bottom and dome of the tank.

Finally, small portions of the solids trapped in the tank structures were manually removed by the solids recovery CIP, which has a vacuum capacity of up to 50 m, and were thrown into gondolas for transport and final disposal.

Many modifications and other embodiments of the invention will come to mind of a person skilled in the art to which this invention pertains, who will benefit from the knowledge presented in the previous description and the accompanying drawings. Therefore, the invention should not be limited to the specific embodiments disclosed, but modifications and other embodiments should be contained within the scope of the appended claims. Although specific terms are used here, they are used in a generic and descriptive sense only and not for the purpose of limitation.

Claims (13)

1. A system for cleaning hydrocarbon storage tanks, characterized in that it is an automated modular system, including: one or more programmable cleaning nozzles (2), made with the possibility of lifting and turning through 360°, which have one or more nozzles with a cleaning range from 0 to 180°; injection and recirculation equipment (C2) configured to supply the required pressure and flow to the cleaning nozzles (2) for injecting chemical mixtures by means of an injection pump or compressor (A1); waste oil separation and recovery equipment configured to centrifuge sludge from the hydrocarbon storage tank and separate solid particles; a sludge recovery module (C1) configured to recirculate at the bottom of the tank and dilute all types of paraffins or unwanted compounds; a chemical mixing tank (C3) and a sludge receiving tank (C4); and equipment (N2) configured to generate and inject inert gas into the reservoir on a continuous basis. 2. System according to claim 1, in which the injection and recirculation equipment (C2) for supplying the required pressure and flow to the cleaning nozzles (2) is mounted on a portable skid. 3. A system according to any one of the preceding claims, wherein the oil waste separation and recovery equipment has at least 50 hp. and at least a process capacity of 10 to 20 m ³ /h. 4. A system according to any one of the preceding claims, wherein the inert gas generation and injection equipment has a constant flow of at least 500 m ³ /h and a pressure of up to 300 psi. 5. A system according to any one of the preceding claims, wherein the inert gas is nitrogen. 6. The system according to any one of the preceding claims, which further includes a mobile laboratory (LAB) and an electrical generator (GE). 7. Chemical mixtures used in the system according to any of the preceding claims, including a cleaning mixture and a mixture for extraction, while the cleaning mixture contains from 30 to 70% xylenes and from 30 to 50% C ₆ -C ₁₀ hydrocarbons by volume, and the recovery mixture comprises, by volume, 30 to 60% xylenes, 30 to 50% C ₆ -C ₁₀ hydrocarbons, and 2 to 10% epoxidized fatty acid esters.

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