RU2286297C1 - Oil storage method and device for realization of said method - Google Patents

Abstract

FIELD: oil storage, possible use in oil, oil-chemical and other industrial branches related to production, storage and distribution of oil.

SUBSTANCE: proposed oil storage method includes creation of liquid substance in bottom part of reservoir, limited by calming layer, having density higher than that of stored oil and not forming stable emulsion with oil, for example, water, containing surfactants, filling of remaining space in reservoir with oil. During oil storage, mixing mode is periodically initiated in zone of liquid environment, and suspension of water solution of surfactants and precipitated hard particles is drained when given amount of bottom precipitation is produced, while fresh liquid substance is fed into bottom part of reservoir until reaching given volume of liquid environment zone, or liquid environment subjected to phase separation may be returned as alternative, after its output from reservoir in mixture. Also proposed is device for oil storage.

EFFECT: increased efficiency when cleaning reservoir from bottom precipitations during oil storage, increased oil storage efficiency.

2 cl, 2 dwg, 1 ex, 1 tbl

Description

The invention relates to the storage of oil and oil products and can be used in the oil, petrochemical and other industries related to the production, storage and distribution of oil.

A known method of storing oil, including partially releasing the reservoir from the contents, installing a stirring device inside the reservoir, pumping an oily diluent into the reservoir, dissolving bottom sediments at optimal temperatures using steam heaters, mixing the resulting mixture to a homogeneous state and pumping out at least part of it from the tank to the decanter for subsequent mechanical centrifugal phase separation. The oil phase is defended and returned to the tanks of the technological installations of the oil refinery for further processing (see US Pat. RF No. 2150341, IPC V 08 V 9/08, publ. 2000.06.10).

Common features of the known and proposed methods are: heating and mixing the contents of the tank at the installation site of the heating and mixing device in order to obtain a homogenized mixture and pumping out at least part of it.

The disadvantages of the known method of storing oil are the need for high costs for the acquisition, storage of hydrocarbon diluent, as well as for the homogenization of the contents of the tank after injection of the diluent, since in the known method of oil storage to remove accumulated bottom sediments, a partial release of the tank from the contents is required, injection of diluent ensure homogenization of the remaining storage product and diluent with heating and stirring. In addition, after pumping out a homogeneous suspension from the reservoir, consisting of a mixture of diluent and stored product with mechanical impurities, additional costs are required for the mechanical centrifugal separation of the suspension into phases, separation of the diluent from the stored product for reuse.

Therefore, the known method is practically unacceptable in autonomous oil storage facilities, in the fields.

A device for storing oil and petroleum products (Transport and storage of petroleum products, 2003, No. 10, p.3-7), containing a double conical bottom, between which is a sandy foundation, a double housing and a cleaning unit for removing water and mechanical impurities, consisting of pipeline, gate valve, filter.

A common feature of the known device and the claimed is a cleaning unit for removing water and solids.

However, the known device has drawbacks, the main of which are the design complexity, the impossibility of stripping mechanical impurities from the oil products contained on them, since the stripping is carried out when the oil product is dispensed from the tank: first, water, impurities “dead residue” are removed through the pipeline of the stripping unit, and then through the same pipeline is an oil product, the complexity of repair work in the event of oil products getting into the sand foundation between the bottoms.

The closest in technical essence and the achieved result to the proposed method is a storage method, comprising filling the tank with a medium having a density higher than the density of the stored oil and not forming a stable emulsion with oil, fresh water with biodegradable surfactant additives and a corrosion inhibitor to form a liquid cushion, which is placed in the tank so that its level is located below the installation level of the loading and unloading pipes of the tank. Further, the method includes filling and emptying the tank with oil, selecting and disposing of the released hydrocarbons from the vapor space of the tank and their subsequent pumping (see US Pat. RF No. 2093442, IPC ⁶ B 65 D 90/30, publ. 1997.10.20).

Common features of the proposed and known methods are:

- creation of a liquid medium zone in the bottom of the tank;

- supply and pumping of oil from the tank;

- the liquid medium has a density higher than the density of the stored oil and does not form a stable emulsion with oil;

- as a liquid medium, water with surfactant additives is used.

However, this method is not effective for storing oil containing solid particles (sand, clay, silt, etc.), since during storage such solid particles, adsorbing the storage products on themselves and settling to the bottom, entrain part of the storage product, this being compacted and forming a hard-to-remove layer under the liquid cushion in the bottom of the tank, which leads to loss of storage products. In addition, the known method does not provide cleaning of the tank from bottom sediments, which must not only be removed, but also cleaned of oil products adsorbed on them.

The closest in technical essence and the achieved result to the proposed device for storing oil is a known device, including a tank, inside which there is a mixing device, steam heaters, pipes for input and output of storage products, and an additional apparatus (decanter) for subsequent mechanical centrifugal separation from the reservoir of the liquid mixture into phases (see US Pat. RF No. 2150341, IPC B 08 V 9/08, publ. 10.06.2000).

Common features of the proposed and known devices are a tank, including a heating device, pipes for the input and output of storage products.

However, the known device does not provide efficient storage of the product, since when cleaning the tank it is necessary to partially free it from the contents (i.e. provide for a reserve tank, pumping devices, which already at this stage will lead to product losses and increased operating costs), pump in an oily diluent and, with the help of a mixing device and steam heaters, ensure homogenization of the mixture, while the entire contents of the mixture are heated and mixed the reservoir, including the diluent, the remaining storage product with bottom sediments, and then this homogeneous mixture is pumped into the decanter for subsequent centrifugal separation to separate the sediment, and additional apparatus is needed to separate the stored product from the diluent for reuse, which makes it impossible to use the known method for offline storage and in fisheries. Additional costs will be required for the disposal of bottom sediments with hydrocarbons adsorbed on them.

The technical task of the proposed invention is to provide cleaning of the tank from bottom sediments in the process of oil storage while increasing the efficiency of oil storage.

The problem is achieved in that in the proposed method for storing oil, including the creation in the bottom of the reservoir zone of a liquid medium having a density higher than the density of the stored oil, such as water containing surface-active substances (surfactants), the supply and pumping of oil from the tank is new the fact that the zone of the liquid medium is limited by a soothing layer, and periodically during the storage of oil in the zone of the liquid medium create a mixing mode, and the resulting suspension of an aqueous solution of surfactant and settled solids are discharged when a predetermined amount of bottom sediment is reached, and fresh liquid medium is supplied to the bottom of the reservoir to a predetermined volume of the liquid medium zone, or the liquid medium subjected to phase separation is returned after it is withdrawn from the tank in the mixture.

In addition, a thermal field is created at the boundary of the liquid medium zone with oil.

In addition, OP-10 or Pemox is used as a surfactant.

In addition, the concentration of surfactants in the aqueous solution is maintained in the range of not higher than 0.2-0.5%.

The inventive combination of features allows during the storage of oil by creating a periodically mixing mode in the zone of the liquid medium, the washing of the deposited solid particles (inorganic sediments) from the storage products with liquid medium (water containing surfactants), which due to lower density than the liquid medium, float out zones of the liquid medium, joining the stored product. Therefore, with the next stirring, solid particles (inorganic sediments) already washed from the storage products are removed from the tank in the resulting suspension with a liquid medium when the specified amount of bottom sediment is reached in it, which ensures effective cleaning of the tank from bottom sediments during storage, and product losses are eliminated storage and the need to clean bottom sediments. In addition, the liquid medium after separation from solid particles, for example, by separation or sludge, is returned to the tank to a predetermined volume of the liquid medium zone, which ensures low operating costs and allows you to combine the proposed method of oil storage with efficient cleaning of tanks from bottom sediments during storage even at facilities remote from technological production (fields, oil storage). The restriction of the liquid medium zone to a soothing layer localizes the created mode of mixing the liquid medium in this zone, eliminating the ingress of the stored product into the liquid medium zone, which also eliminates the loss of this product, increasing storage efficiency. The creation of a thermal field at the boundary of the liquid medium zone with oil creates a preliminary stage of desorption of storage products adsorbed by solid particles deposited in the liquid medium zone, which allows more thorough washing of solid particles during mixing in this zone and, as a result, increases the efficiency of food storage and removal of bottom sediments.

In addition, the use of OP-10 or Pemox and other surfactants as a surfactant when its concentration in water is not higher than 0.2-0.5% allows you to effectively clean the particles of mechanical impurities from oil products adsorbed on them.

The task is also achieved by the fact that in the proposed device for storing oil, which includes a tank with oil inlet and outlet nozzles, a heating device, it is new that the heating device is made in the form of a tubular-lattice web having heat supply inlet and outlet pipes installed in the cross section of the bottom part of the body, the oil inlet and outlet pipes are located above the tubular-lattice web, and the inlet nozzles are made in the bottom part below the tubular-lattice web and liquid outlet, which are interconnected through a circulation pump installed on the outside of the tank.

The described set of features of the proposed device allows you to create a local zone of a liquid medium in the bottom of the tank and periodically provide a mixing mode in this zone of the tank during storage, washing the deposited solid particles (inorganic sediments) from storage products with a liquid medium (water containing surfactant). Therefore, solid particles (inorganic sediments) already washed from the storage products, dispersed in a liquid medium when it reaches a predetermined amount of bottom sediment, are removed from the tank with regular stirring, which ensures effective cleaning of the tank from bottom sediments during storage, while eliminating the loss of storage products . In addition, the liquid medium after separation from solid particles (inorganic sediments), for example, by sedimentation or separation, is returned to the tank to a predetermined volume of the liquid medium zone, which provides low operating costs and allows you to combine the proposed method of oil storage with efficient cleaning of tanks from bottom sediments during storage even at facilities remote from technological production (fields, oil storage facilities). The heat supply to the tubular lattice web creates a preliminary stage of desorption of storage products adsorbed by settling solid particles, which allows more thoroughly washing solid particles during mixing, increasing the efficiency of oil storage and removal of bottom sediments.

The proposed invention is illustrated in figure 1. Figure 2 presents a cross section of a tubular lattice web.

The proposed method is carried out in the following sequence. Before filling the reservoir with the storage product (oil), a zone of a liquid medium is created in the bottom of the reservoir, having a density higher than the density of the stored oil and not forming a stable emulsion with the oil. To do this, water containing surfactants (surfactants) is supplied to the tank. As a surfactant, OP-10 or Pemox and others are used, and the concentration of surfactants in an aqueous solution is maintained within the range of no higher than 0.2-0.5%. The zone of the liquid medium is limited by the stilling layer, and after creating the liquid layer, the remaining volume of the tank is filled with oil. During its storage, solid particles are deposited in the bottom, entraining the storage products adsorbed by them. The creation periodically in the zone of the liquid medium (during the oil storage) of the mixing mode, in which the suspension of the settled solid particles formed during the oil storage is mixed with the liquid medium, ensures that the adsorbed storage product is washed off from the surface of the solid particles, which floats due to the lower density and attaches to bulk storage product. The suspension formed during subsequent stirring is discharged after reaching a predetermined amount of bottom sediment, subjecting it to subsequent phase separation, after which the liquid medium is returned to the bottom of the tank to a predetermined volume of liquid medium (to the level of the stilling layer), and the solid sediment freed from storage products used, for example, as a building material.

A thermal field can be created at the boundary of the liquid medium zone with oil, which provides a partial stripping of the adsorbed storage product from the surface of the deposited solid particles.

Example.

The proposed method was tested on a laboratory setup, shown in figure 1.

For the experiment, an oil sample was taken, taken at the oil treatment point No. 4 of the Slavyansk field of the Krasnodar Territory after preliminary desalination and dehydration. The density of oil is 0.92 g / cm ³ , the content of solids is 3.7% by weight.

In a 15-liter tank through the lower tube was poured 3 l of an aqueous solution of OP-10 or Pemox with a concentration of not more than 0.2% by weight. for OP-10 and 0.05% weight. for pemox. Surfactant concentrations were selected according to the melon literature, which are optimal for the selected surfactants. The created zone of the aqueous solution was limited by a tubular coil, which was connected to the thermostat, providing a thermal field at a given tank level. Then 8 liters of oil were carefully poured into the tank. Then, daily, twice a day, in the zone of an aqueous surfactant solution for 10 min, a mixing mode was created using a stirrer with a rod diameter of 3 mm. Previously, before creating a mixing mode for one hour, water heated to 80 ° C was supplied from the thermostat to the tubular coil. After a week, the liquid medium was discharged through a drain pipe into a previously prepared container. After filtration, the aqueous surfactant solution was returned to the tank through the funnel and the experiment was continued until the next surfactant aqueous solution was drained.

The precipitate was analyzed for hydrocarbon content. The hydrocarbon content ranged from 0.2 to 0.5% weight.

The results of the experiment are summarized in table.

N p / p Surfactant Conc. Surfactant,% weight. Heating Will Separate. zones
° C The amount of filtered precipitate, g Total% of total content Note After 1 week In 2 weeks In 3 weeks one OP-10 0.2 22 47.1 33.6 23.6 38.3 With the return of the fluid after centrifugation 2 OP-10 0.2 80 92.4 76,4 58.3 83,4 With weekly fluid change 3 OP-10 1.3 80 88.7 80.7 56.1 82.8 - "" - four Pemox 0.5 22 50,2 32.9 26,4 40,2 - "" - 5 Pemox 0.5 80 110.3 83,4 43.5 87.1 - "" - 6 Pemox 1.7 80 93.7 82.7 59.1 86.5 - "" -

The obtained results confirm the effectiveness of the proposed method, and during long-term storage, smaller particles of inorganic compounds that were originally present in the initial product will be removed from the oil.

The proposed device for storing oil, shown in figure 1, contains a reservoir 1 with nozzles for the inlet and outlet of oil 2 and 3, respectively. In the bottom part of the tank 1, a tubular-lattice web 4 is installed (see FIG. 2), forming a zone for the liquid medium 5. Pipes 2 and 3 are connected to the tank 1 above the tubular-lattice web 4. In the bottom part of the body of the tank 1 below the tubular lattice web 4 there are nozzles for entry and exit of the liquid medium 6 and 7, respectively. The pipe 6 can be installed tangentially to the body of the tank 1 to increase the efficiency of mixing the liquid medium in zone 5. The tubular-lattice web 4 is equipped with pipes for the inlet and outlet of the coolant 8 and 9, respectively. The nozzles 6 and 7 are interconnected through a circulation pump 10, which is installed outside the tank and provides mixing of the liquid medium, and if necessary serves to pump the liquid suspension into the separator tank 11 to sediment it or to supply fresh (new) to the bottom of the tank 1 portions of a liquid medium from its preparation tank 12 or liquid medium after settling it in the separator vessel 11. The tanks 11 and 12 are connected by a pipeline to the suction pipe of the circulation pump 10, and the discharge pipe of the pump 10 Inonii with the pipe 6 in the bottom part of the tank 1 and the separator tank 11, where the liquid medium is pumped out periodically with suspended particles.

A device for storing oil works as follows. An aqueous surfactant solution is supplied to the tank 1 through the pipe 6 to zone 5 from the tank 12 by the circulation pump 10 to a predetermined volume of zone 5, i.e. to the tubular lattice web 4. Then through the pipe 2 in the tank 1 serves oil. In the process of oil storage periodically in zone 5 using a circulation pump 10 create a mixing mode. After the next mixing in accordance with a predetermined quantitative or temporal parameter relative to the bottom sediment, it is removed through the pipe 7 into the separator vessel 11. In the separator vessel, the mixture is separated into an aqueous surfactant solution, which is returned to zone 5, and the sediment freed from oil products Which is used further as building material.

Claims (5)

1. A method of storing oil, including creating in the bottom of the reservoir a zone of a liquid medium having a density higher than the density of the stored oil, for example, water containing surfactants, supplying and pumping oil from the tank, characterized in that the zone of the liquid medium is limited a sedative layer, and periodically during the storage of oil in the zone of the liquid medium create a mixing mode, and the resulting suspension of an aqueous solution of surfactants and settled solid particles is removed when reaching the specified the amount of bottom sediment, and in the bottom part of the reservoir to a predetermined volume of the zone of the liquid medium, fresh liquid medium is supplied or the liquid medium subjected to phase separation is returned after it is withdrawn into the mixture from the tank. 2. The method according to claim 1, characterized in that at the boundary of the zone of the liquid medium with oil create a thermal field. 3. The method according to claim 1, characterized in that as a surfactant use OP-10 or Pemox. 4. The method according to claim 1, characterized in that the concentration of surfactant in the aqueous solution is maintained within the range of not higher than 0.2-0.5%. 5. A device for storing oil, including a tank with nozzles for entering and exiting oil, a heating device, characterized in that the heating device is made in the form of a tubular-lattice web having nozzles for supplying and discharging a heat carrier installed in a cross section of the bottom part of the tank body, nozzles the oil inlet and outlet are located above the tubular-lattice web, and in the bottom part below the tubular-lattice web there are made inlets of the inlet and outlet of a liquid medium, which are connected between through a circulation pump installed on the outside of the tank.

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