CN120551142A - Crude oil storage tank cleaning method - Google Patents
Crude oil storage tank cleaning methodInfo
- Publication number
- CN120551142A CN120551142A CN202510750279.3A CN202510750279A CN120551142A CN 120551142 A CN120551142 A CN 120551142A CN 202510750279 A CN202510750279 A CN 202510750279A CN 120551142 A CN120551142 A CN 120551142A
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- China
- Prior art keywords
- crude oil
- storage tank
- oil storage
- mixture
- cleaning
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B08—CLEANING
- B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
- B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto
- B08B9/08—Cleaning containers, e.g. tanks
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B08—CLEANING
- B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
- B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto
- B08B9/08—Cleaning containers, e.g. tanks
- B08B9/093—Cleaning containers, e.g. tanks by the force of jets or sprays
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Cleaning In General (AREA)
Abstract
The invention belongs to the technical field of crude oil storage, and discloses a crude oil storage tank cleaning method which comprises the steps of S1, adding thin oil into a crude oil storage tank, stirring a mixture in the crude oil storage tank, stopping stirring when the viscosity of the mixture in the crude oil storage tank is detected to be less than or equal to a preset viscosity, standing for a first preset time, extracting crude oil in the mixture in the crude oil storage tank to the outside of the crude oil storage tank, S2, adding a first cleaning liquid into the crude oil storage tank, stirring the mixture in the crude oil storage tank, extracting the mixture with fluidity in the crude oil storage tank to the outside of the crude oil storage tank after stirring for a second preset time, S3, spraying a second cleaning liquid into the crude oil storage tank, standing for a third preset time, and extracting a cleaning product in the crude oil storage tank to the outside of the crude oil storage tank, S4. The crude oil storage tank is cleaned in the modes of stirring, cleaning liquid spraying, cleaning and the like, so that the cleaning effect of the crude oil storage tank is improved.
Description
Technical Field
The invention relates to the technical field of crude oil storage, in particular to a method for cleaning a crude oil storage tank.
Background
The crude oil storage tank is a steel sealed container for storing crude oil and other petroleum products, and is mainly applied to the industrial fields of refineries, oil fields, oil reservoirs and the like. The sediment in the crude oil storage tank is formed by natural deposition at the bottom of the crude oil storage tank due to the fact that mechanical impurities, soil, sand grains, heavy metal salts and heavy oil components such as asphaltene, colloid and paraffin are contained in the oil in the process of storing the oil, and the sediment in the crude oil storage tank has the characteristics of high viscosity, strong cohesiveness, high emulsification degree, complex components, slow natural sedimentation and the like.
The crude oil storage tank is cleaned and overhauled internationally usually every about 6 years, the domestic petroleum industry prescribes that the first time of opening and overhauling a newly-built steel oil tank is not longer than 10 years, and the second time and later time of opening and overhauling the tank are usually 5-7 years. At present, a COWS (Crude Oil WASHER SYSTEM) storage tank mechanical cleaning technology is generally adopted for cleaning sediment at the bottom of an inner tank of a large-scale crude oil storage tank in China. COWS cleaning is a cleaning technology of 'similar oil products, totally closed and mechanical automatic circulation', and is used for cleaning sediment in a tank by utilizing crude oil as a cleaning medium and combining high-pressure spraying and circulating flow. That is, the COWS technology relies on physical flushing and limited solvency of crude oil, and is difficult to cope with complex deposits, resulting in poor cleaning of crude oil storage tanks.
Accordingly, there is a need for a crude oil tank cleaning method to solve the above problems.
Disclosure of Invention
The invention aims to provide a crude oil storage tank cleaning method, which aims to solve the problem of poor cleaning effect of a crude oil storage tank in the prior art.
The technical scheme adopted by the invention is as follows:
The crude oil storage tank cleaning method comprises the following steps:
S1, adding thin oil into a crude oil storage tank, stirring a mixture in the crude oil storage tank, stopping stirring when the viscosity of the mixture in the crude oil storage tank is detected to be less than or equal to a preset viscosity, standing for a first preset time, and extracting crude oil in the mixture in the crude oil storage tank to the outside of the crude oil storage tank;
S2, adding a first cleaning solution into the crude oil storage tank, stirring the mixture in the crude oil storage tank, and extracting the mixture with fluidity in the crude oil storage tank out of the crude oil storage tank after stirring for a second preset time;
S3, spraying a second cleaning solution into the crude oil storage tank, standing for a third preset time, and spraying a third cleaning solution into the crude oil storage tank;
S4, extracting the cleaning products in the crude oil storage tank to the outside of the crude oil storage tank.
Further, step S1 includes the steps of:
S11, adding thin oil into the crude oil storage tank, stirring the mixture in the crude oil storage tank, stopping stirring when the viscosity of the mixture in the crude oil storage tank is detected to be less than or equal to a preset viscosity, and standing for a first preset time;
S12, extracting the crude oil in the mixture in the crude oil storage tank to the outside of the crude oil storage tank, detecting the liquid level in the crude oil storage tank and the thickness of sediment in the mixture, and stopping extracting the crude oil in the crude oil storage tank when the liquid level in the crude oil storage tank is reduced to be close to the thickness of the sediment.
Further, between step S12 and step S2, the following steps are further included:
and flushing the crude oil storage tank by using crude oil in the mixture in the crude oil storage tank, and extracting the crude oil in the crude oil storage tank to the outside of the crude oil storage tank after flushing.
Further, between step S2 and step S3, step S2' is further included:
And step S2, after a fourth preset time interval, adding the first cleaning solution into the crude oil storage tank again, wherein the volume concentration of the first cleaning solution is 2-3 times that of the first cleaning solution added in the step S2, stirring the mixture in the crude oil storage tank, and after a second preset time, extracting the mixture with fluidity in the crude oil storage tank out of the crude oil storage tank.
Further, between step S2 and step S3, step S30 is further included:
And opening a manhole of the crude oil storage tank, carrying out ventilation treatment on the interior of the crude oil storage tank, and introducing inert gas into the crude oil storage tank after the ventilation treatment.
Further, the following steps are included between the step S30 and the step S3:
and moving the residual mixture at the bottom of the crude oil storage tank to a manhole, and extracting the mixture out of the crude oil storage tank.
Further, in step S3, the second cleaning solution and the third cleaning solution are sprayed manually.
Further, between the step S3 and the step S4, the method further includes the following steps:
Judging whether the crude oil storage tank is qualified in cleaning, if so, executing the step S4, and if not, executing the step S3 again.
Further, the volume concentration of the first cleaning liquid is 0.01% -5%, and the ratio of the volume of sediment in the mixture in the crude oil storage tank to the volume of the first cleaning liquid is 2.5:1% -1:4.
Further, the preset viscosity is preset apparent viscosity or preset kinematic viscosity, the preset apparent viscosity is 300 mPas, and the preset kinematic viscosity is 350cSt.
The invention has the beneficial effects that:
The invention provides a crude oil storage tank cleaning method which comprises the following steps of S1, adding thin oil into a crude oil storage tank, stirring a mixture in the crude oil storage tank, stopping stirring when the viscosity of the mixture in the crude oil storage tank is detected to be less than or equal to a preset viscosity, standing for a first preset time, extracting crude oil in the mixture in the crude oil storage tank to the outside of the crude oil storage tank, S2, adding a first cleaning liquid into the crude oil storage tank, stirring the mixture in the crude oil storage tank for a second preset time, extracting the mixture with fluidity in the crude oil storage tank to the outside of the crude oil storage tank, S3, spraying a second cleaning liquid into the crude oil storage tank, standing for a third preset time, and then spraying a third cleaning liquid into the crude oil storage tank, and S4, extracting a cleaning product in the crude oil storage tank to the outside of the crude oil storage tank. Through adding thin oil into a crude oil storage tank, stirring the mixture in the crude oil storage tank, reducing the viscosity of the mixture in the crude oil storage tank, extracting crude oil in the mixture in the crude oil storage tank to the outside of the crude oil storage tank, then utilizing a first cleaning liquid, a second cleaning liquid and a third cleaning liquid to clean the mixture in the crude oil storage tank respectively, extracting cleaning products in the crude oil storage tank to the outside of the crude oil storage tank, namely cleaning the crude oil storage tank in a stirring mode, a cleaning liquid injection cleaning mode and the like, and improving the cleaning effect on the crude oil storage tank.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following description will briefly explain the drawings needed in the description of the embodiments of the present invention, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the contents of the embodiments of the present invention and these drawings without inventive effort for those skilled in the art.
Fig. 1 is a flowchart of a crude oil tank cleaning method according to an embodiment of the present invention.
Detailed Description
In order to make the technical problems solved, the technical scheme adopted and the technical effects achieved by the invention more clear, the technical scheme of the invention is further described below by a specific embodiment in combination with the attached drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the drawings related to the present invention are shown.
It should be noted that like reference numerals and letters refer to like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
In the description of the present invention, unless explicitly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, and may, for example, be fixedly connected, detachably connected, or integrally formed, mechanically connected, electrically connected, directly connected, indirectly connected through an intervening medium, or in communication between two elements or in an interaction relationship between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
In the present invention, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature. In the description of the present embodiment, unless specifically stated otherwise, "a plurality of" means two or more.
In the description of the present embodiment, the terms "upper", "lower", "right", etc. orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of description and simplicity of operation, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the invention. Furthermore, the terms "first," "second," and the like, are used merely for distinguishing between descriptions and not for distinguishing between them.
It will be understood that when an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present.
The technical scheme of the invention is further described below by the specific embodiments with reference to the accompanying drawings.
The embodiment provides a crude oil storage tank cleaning method, which improves the cleaning effect of the crude oil storage tank.
Illustratively, as shown in FIG. 1, a crude oil storage tank cleaning method includes the steps of:
s1, adding thin oil into a crude oil storage tank, stirring a mixture in the crude oil storage tank, stopping stirring when the viscosity of the mixture in the crude oil storage tank is detected to be less than or equal to a preset viscosity, standing for a first preset time, and extracting crude oil in the mixture in the crude oil storage tank to the outside of the crude oil storage tank;
s2, adding a first cleaning solution into the crude oil storage tank, stirring the mixture in the crude oil storage tank, and extracting the mixture with fluidity in the crude oil storage tank out of the crude oil storage tank after stirring for a second preset time;
s3, spraying a second cleaning solution into the crude oil storage tank, standing for a third preset time, and spraying a third cleaning solution into the crude oil storage tank;
s4, extracting the cleaning products in the crude oil storage tank to the outside of the crude oil storage tank.
It can be understood that by setting the steps, thin oil is added into the crude oil storage tank, the mixture in the crude oil storage tank is stirred, the viscosity of the mixture in the crude oil storage tank is reduced, the mixture is kept still for a first preset time, crude oil in the mixture in the crude oil storage tank is extracted out of the crude oil storage tank, then the mixture in the crude oil storage tank is stirred and cleaned by using the first cleaning liquid, the mixture with fluidity in the crude oil storage tank is extracted out of the crude oil storage tank, then the mixture in the crude oil storage tank is cleaned by using the second cleaning liquid and the third cleaning liquid, and cleaning products in the crude oil storage tank are extracted out of the crude oil storage tank, namely, the crude oil storage tank is cleaned by stirring, cleaning liquid spraying, and the like, so that the cleaning effect of the crude oil storage tank is improved.
It can be further thought that the crude oil storage tank is cleaned in the modes of stirring, cleaning liquid spraying, cleaning and the like, and the combined action of the two modes improves the cleaning effect on the crude oil storage tank, the crude oil storage tank is not required to be used repeatedly, and the cleaning efficiency is high.
In this embodiment, the first preset time, the second preset time and the third preset time are all any time from 0 to 3 hours, and specific values of the first preset time, the second preset time and the third preset time can be determined according to actual use requirements, which is not specifically limited in this embodiment.
Step S1 comprises the steps of:
S11, adding thin oil into a crude oil storage tank, stirring the mixture in the crude oil storage tank, stopping stirring when the viscosity of the mixture in the crude oil storage tank is detected to be less than or equal to a preset viscosity, and standing for a first preset time;
s12, extracting the crude oil in the mixture in the crude oil storage tank to the outside of the crude oil storage tank, detecting the liquid level in the crude oil storage tank and the thickness of sediment in the mixture, and stopping extracting the crude oil in the crude oil storage tank when the liquid level in the crude oil storage tank is reduced to be close to the thickness of the sediment.
It will be appreciated that by providing the above steps, by detecting the liquid level in the crude oil storage tank and the thickness of the sediment in the mixture, and reducing the liquid level in the crude oil storage tank to a level close to the thickness of the sediment, in the process, by adding thin oil to the crude oil storage tank and stirring the mixture in the crude oil storage tank, the viscosity of the crude oil in the mixture is reduced, and after a first preset time of standing, the crude oil present in the upper layer of the mixture can be extracted, so that the liquid level in the crude oil storage tank is reduced to a level close to the thickness of the sediment, and the collection of the crude oil is facilitated.
The thin oil is an oil product or solvent with low viscosity and high solubility, and is mainly used for dissolving or diluting stubborn sediments such as crude oil, asphaltene, wax and the like remained in a crude oil storage tank.
Between step S12 and step S2, there is further included a step of flushing the crude oil storage tank with crude oil in the crude oil storage tank mixture, and extracting crude oil in the crude oil storage tank to the outside of the crude oil storage tank after flushing. It can be understood that the crude oil in the mixture in the crude oil storage tank is used as the same kind of washing oil to wash the high-level mixture in the crude oil storage tank, so that the collection effect of the crude oil can be further improved, and the workload of subsequent treatment of washing products is reduced.
In this embodiment, in step S2, after stirring for a second preset time, the mixture in the crude oil storage tank may be left for 8-12 hours and then extracted out of the crude oil storage tank. The range of the value of the volume ratio of sediment in the mixture in the crude oil storage tank to the volume ratio of the first cleaning liquid is 2.5:1-1:4, the cleaning temperature is 10-30 ℃, the 2h is more than or equal to the second preset time is more than or equal to 0.5h, and the stirring speed is controlled to be 50-150 rpm.
In this example, the mixture was crude oil and sediment. The first cleaning fluid may be a crude oil viscosity reducer solution or a chemical flow improver solution to reduce the viscosity of the mixture for ease of draining. The second cleaning liquid and the third cleaning liquid can be water-soluble cleaning liquids. The volume concentration of the first cleaning solution, the second cleaning solution and the third cleaning solution can be in the range of 0.01% -5%. The viscosity reducer and the chemical flow improver of crude oil are selected as cleaning liquid, the cleaning liquid is required to be oil-soluble, and components such as nitrogen, phosphorus, sulfur and the like which have influence on the refining of the downstream crude oil are not contained, and meanwhile, the average corrosion rate of the cleaning liquid on the wall material of a storage tank is less than or equal to 0.076mm/a. The specific compositions of the crude oil viscosity reducer solution, the chemical flow improver solution and the water-soluble cleaning liquid are all the prior art, and the embodiment will not be repeated.
The volume concentrations of the first cleaning liquid, the second cleaning liquid and the third cleaning liquid can be determined according to aspects of viscosity, specific gravity, rheological property and the like of on-site sediment, and the requirement of slow actual use is met.
In this embodiment, the preset viscosity may be a preset apparent viscosity or a preset kinematic viscosity, the preset apparent viscosity is 300mpa·s, and the preset kinematic viscosity is 350cSt. The kinematic viscosity and the kinematic viscosity are in the prior art, and the description is omitted in this embodiment.
In the embodiment, the area where the mixture in the crude oil storage tank is stirred is mainly the position where the thickness of the sediment in the crude oil storage tank is thicker and the peripheral position thereof, the viscosity test is timely carried out on the oil sludge of each cleaning position during the cleaning process, the apparent viscosity of the cleaned mixture is controlled to be less than or equal to 300 mPa.s or the kinematic viscosity is less than or equal to 350cSt, the viscosity reduction requirement can be considered to be met, and when the cleaning is finished, the flowable mixture is transferred to the bypass tank until the liquid level in the crude oil storage tank reaches the position as low as possible.
Further, between step S2 and step S3, step S2' is further included:
And after the fourth preset time is spaced in the step S2, adding the first cleaning solution into the crude oil storage tank again, wherein the volume concentration of the first cleaning solution is 2-3 times that of the first cleaning solution added in the step S2, stirring the mixture in the crude oil storage tank, and after the second preset time is carried out, extracting the mixture with fluidity in the crude oil storage tank out of the crude oil storage tank.
It can be understood that through setting up step S2', can carry out the twice washing of crude oil storage tank, and the volumetric concentration of the first washing liquid is different in the twice washing process, and the interval fourth presets time in the middle, is convenient for improve the cleaning performance to the crude oil storage tank, can further improve the rate of recovery and the cleaning efficiency of oil. In this embodiment, the fourth preset time may be 12h. Of course, in other embodiments, the volume concentration of the first cleaning solution added to the crude oil storage tank in step S2' may be the same as the concentration of the first cleaning solution added to the crude oil storage tank in step S21, and may be determined according to the actual use requirement, which is not described in detail in this embodiment.
The number of times of cleaning the mixture in the crude oil storage tank with the first cleaning liquid can be determined according to the liquid level in the crude oil storage tank and the thickness of the sediment detected, and the crude oil storage tank can be protected by nitrogen gas from the nitrogen generator through the strut Kong Jiazhu on the floating roof.
In the embodiment, in the step S2, a first cleaning liquid is added into a crude oil storage tank for cleaning, the prepared first cleaning liquid is pumped and pressurized by a suction pump and filled by struts uniformly selected from the outermost struts and the inner rings of the tank top (ensuring that dead angles of a top plate are not covered), each floating roof strut is cleaned for at least 1h, oil-containing wastewater (cleaning products) in the crude oil storage tank is completely pumped into a bypass tank after cleaning is finished, after the step S2 is separated by a fourth preset time, the first cleaning liquid is added into the crude oil storage tank again for cleaning, the first cleaning liquid filling method is the same as that in the step S2, after the first cleaning liquid is filled, a cleaning gun is set into a bottom plate cleaning mode, so that the cleaning gun extends from the center point to the periphery, the waste water and thick oil around a manhole can be properly transferred to the bypass storage tank by a screw pump in the cleaning process, and finally the cleaning products (oil-containing waste water) in the crude oil storage tank are completely pumped into the bypass tank by a hydraulic screw pump.
Further, between step S2 and step S3, step S30 is further included:
And opening a manhole of the crude oil storage tank, ventilating the crude oil storage tank, and introducing inert gas into the crude oil storage tank after the ventilation treatment.
It can be appreciated that in this embodiment, before further cleaning the storage tank, the blind plates of the oil inlet and outlet pipelines are required to be isolated, the manhole is opened, the axial flow fan is installed to perform forced ventilation, the sealing element is removed, and inert gas is introduced into the crude oil storage tank after ventilation treatment to ensure the safety of the subsequent cleaning operation. In this embodiment, inert gases including, but not limited to, nitrogen, may be used with the nitrogen generator and filled into the crude oil storage tank through the strut holes in the float roof.
Further, the following steps are included between the step S30 and the step S3:
and (3) moving the residual mixture at the bottom of the crude oil storage tank to a manhole and extracting the mixture outside the crude oil storage tank.
In this embodiment, the floating roof may be removed before performing the above steps. Under the condition of forced ventilation and floating roof removal of the crude oil storage tank, workers can enter the tank on the premise of wearing protective articles, and the push plate is used for pushing the residual mixture (namely part of the mixture) at the bottom of the tank to a manhole and extracting the residual mixture out of the crude oil storage tank. And then spraying a second cleaning solution into the crude oil storage tank, for example, uniformly spraying the second cleaning solution onto accessories such as tank walls, tank bottoms and pillar surfaces in the crude oil storage tank, standing for a third preset time (which can be 1 h), fully dissolving the mixture in the tank body by the second cleaning solution, spraying the third cleaning solution into the crude oil storage tank until the accessories such as the tank walls and the pillar surfaces are free from adhering oil sludge or exposing metallic luster, and sucking oily wastewater (the residual mixture) in the crude oil storage tank into a sewage tank outside the tank by a hydraulic screw pump so as to realize comprehensive cleaning of the crude oil storage tank.
In this embodiment, the spraying of the second cleaning solution and the third cleaning solution in step S3 is performed manually. It can be appreciated that the spraying of the second cleaning liquid and the third cleaning liquid is performed by using the manual handheld high-pressure spray gun, so that adjustment can be performed according to different conditions, for example, the cleaning time of the position can be appropriately increased according to the heavier mixture in the crude oil tank, so as to improve the cleaning effect.
In this embodiment, between step S3 and step S4, the following steps are further included:
Judging whether the crude oil storage tank is qualified in cleaning, if so, executing the step S4, and if not, executing the step S3 again. It can be understood that if the crude oil storage tank is found to be cleaned qualified, the mixture in the crude oil storage tank is normally extracted out of the crude oil storage tank, and if the mixture is not qualified, the step S3 is re-executed to clean the crude oil storage tank, so that the cleaning effect of the crude oil storage tank is ensured. Aiming at how to judge whether the cleaning of the crude oil storage tank is qualified, the cleaning can be confirmed according to actual conditions, and the actual use requirements can be met, and the embodiment is not particularly limited.
For the treatment of the cleaning products (oily wastewater) collected from the cleaning of crude oil storage tanks. In this embodiment, the treatment of the oily wastewater is divided into two steps of demulsification and clear water deoiling treatment.
The demulsification treatment is that demulsification is carried out on the oily wastewater under the condition of room temperature by adopting a demulsifier, the adding amount of the demulsifier can be optimized and determined through an on-site indoor test, the oily wastewater after being added with the drugs is aerated and stirred for 1-2 hours by using an aeration pump during demulsification, the mixture is uniformly mixed and stood, when an oil-water interface is stable and the thickness of an oil layer is unchanged, oil skimming is carried out to recover upper layer oil slick, the oil content of lower layer water is measured, the oil content of the wastewater after demulsification is required to be less than or equal to 200mg/L, and if the primary demulsification effect does not reach the aim, secondary demulsification or proper compound demulsifier (and adding amount) can be carried out until the oil content of the wastewater after demulsification is less than or equal to 200 mg/L.
The clean water oil removal treatment is that when the oil content of wastewater after demulsification is 200-40 mg/L, oil removal treatment is carried out on the oil-containing wastewater by adopting a water removal agent, the addition amount of the water removal agent can be determined through on-site indoor test in an optimized way, after the water removal agent is added, the oil-containing wastewater after dosing is aerated and stirred by adopting an aeration pump for 1-2 hours, so that the oil-containing wastewater is fully mixed for oil removal, standing, when an oil-water interface is stable and the thickness of an oil layer is unchanged, skimming oil is carried out to recover upper layer floating oil, the oil content in lower layer water is measured, and the oil content of the wastewater after oil removal is required to be less than 40mg/L.
The demulsifier is a surfactant capable of breaking an emulsion. Can remove water from crude oil and heavy oil to make the water content meet the requirement, and can be obtained by polymerizing fatty alcohol, propylene oxide and ethylene oxide. The water scavenger is colorless to pale yellow uniform liquid, and is mainly used for an oilfield sewage treatment system to reduce the oil content of sewage.
It can be appreciated that the upper layer oil slick can be recovered by the treatment of the cleaning product in the embodiment, and the oil content of the wastewater after oil removal is low, so that the waste of resources is avoided, and the probability of environmental pollution of the cleaning product is reduced.
In this embodiment, a 50000m 3 crude oil storage tank is taken as an example of an external floating roof crude oil storage tank. The parameters of the crude oil storage tank are that the tank height is 19.5m, the diameter is 60m, 119 struts are distributed on the tank top, the storage medium in the tank is crude oil, the density of the crude oil is 800.9-877.8 kg/m 3, the total sediment (sludge) volume in the tank is 5790+/-469 m 3, the hard sediment volume is 4356+/-353 m 3, the sediment in the tank is unevenly distributed, the thickness of the total sediment is 3.5-5.2 m, the thickness of the hard sediment at the tank bottom is also 3.0-4.8 m, the thickness of the sediment at other parts is basically 1.2-1.4 m, and the cleaning method of the crude oil storage tank comprises the following steps:
When the liquid level in the crude oil storage tank is 6.5m, adding thin oil for stirring, then extracting crude oil in the mixture to the receiving side tank until the liquid level in the crude oil storage tank is about 5m, and stopping extracting.
The crude oil (with the kinematic viscosity of 45.33 cSt) in the mixture in the crude oil storage tank is used as the same-kind washing oil to be washed at the high-level sediment for 2 hours until the kinematic viscosity of the high-level sediment at each pillar in the tank is less than or equal to 350cSt, and then the crude oil in the crude oil storage tank is transferred outwards until the crude oil level in the crude oil storage tank is reduced to about 2.7 m.
The method comprises the steps of adding a first cleaning solution to clean sediment in a crude oil storage tank, cleaning and stirring the sediment, controlling the settling time to be 8-12 h after cleaning, carrying out external transfer of the crude oil storage tank, carrying out 2 rounds of cleaning, adding the first cleaning solution from 20 columns at the first time, stirring and cleaning the sediment beside each column for 2h, transferring the cleaned and stirred crude oil to the external of the crude oil storage tank, reducing the liquid level in the crude oil storage tank to about 1m, adding the first cleaning solution from 20 columns for the second time, adding the first cleaning solution from the second time for 12h at intervals of 12h, adding the first cleaning solution from 10 columns each time, and stirring and cleaning the sediment beside the columns for 2h. The oil product and sediment in the crude oil storage tank are transferred out of the crude oil storage tank through the auxiliary mechanical cleaning of the first cleaning liquid of 2 rounds and are recovered into the receiving storage tank. The whole cleaning operation time was 22d.
Spraying a second cleaning solution into the crude oil storage tank, standing for a third preset time, and spraying a third cleaning solution into the crude oil storage tank, wherein the dosage of the second cleaning solution and the third cleaning solution is 2m 3 each time, the tank wall, the top plate and the bottom plate of the crude oil storage tank are respectively cleaned, the cleaning effect is good, and all cleaning products in the tank are pumped into a receiving storage tank through a hydraulic screw pump, so that the recovery rate of oil products is improved;
Judging whether the cleaning in the crude oil storage tank is qualified, if so, carrying out the process of indicating that the cleaning of the crude oil storage tank is finished, if not, continuously spraying a second cleaning liquid into the crude oil storage tank, standing for a first preset time and a third preset time, spraying a third cleaning liquid into the crude oil storage tank, for example, properly increasing the volume concentration of the second cleaning liquid, spraying the third cleaning liquid on sediment positions remained on the tank wall, the top plate, the bottom plate, the pillar surface, dead corners and the like, staying for 1h, spraying the third cleaning liquid by using a high-pressure spray gun, carrying out the manual cleaning, and judging that the cleaning of the crude oil storage tank is qualified and the expected cleaning effect and acceptance condition are reached if the bottom surface of a floating bin in the cleaned crude oil storage tank, the pillar and the bottom plate of the central tank are exposed to the original metal luster;
The 10m 3 oily wastewater produced by cleaning is subjected to chemical demulsification and water agent deoiling treatment, wherein the dosage of the demulsifier is 3% (m/v), the dosage concentration of the water agent is 20mg/L (m/v), the oil content of the oily wastewater after demulsification is reduced to 59.75mg/L, the expected deoiling rate is less than or equal to 200mg/L, the oily wastewater after demulsification is light yellow after deoiling by the water agent, and is transparent, the oil content of the oily wastewater is reduced to 34.3mg/L, and the expected deoiling target less than or equal to 40mg/L is achieved.
In this example, a 3m 3 horizontal crude oil tank for storing crude oil dirty oil is taken as an example. The parameters of the crude oil storage tank are that the height of the tank is 1.65m and the diameter is 1.6m, the storage medium in the tank is crude oil dirty oil, the crude oil density is about 850.9kg/m 3, the total sediment volume in the tank is about 0.6m 3, and the sediment distribution in the crude oil dirty oil storage tank is relatively uniform. The crude oil storage tank cleaning method can also be as follows:
the first cleaning solution, the second cleaning solution and the third cleaning solution are respectively added into the crude oil storage tank from the manhole of the crude oil storage tank according to the volume concentration of 0.01%;
Opening an oil pipeline valve, slowly injecting crude oil (or thin oil with the viscosity of 4.465 cSt) into a crude oil storage tank, observing the liquid level change in the crude oil storage tank, and stopping injecting crude oil into the crude oil storage tank when the liquid level in the crude oil storage tank is about 2.0m 3;
starting a nitrogen making machine to inject nitrogen into the crude oil storage tank so as to ensure that the oxygen content in the crude oil storage tank is lower than 8%, starting a hydraulic station, and circularly stirring and cleaning sediment in the crude oil storage tank for 2 hours through a screw pump;
Collecting an oil sample in a crude oil storage tank, observing the flowing condition and the wall sticking condition of sediment, and measuring the viscosity of the sediment, wherein the measured kinematic viscosity is 3.667-5.457 cSt (the sediment at the bottom of the crude oil storage tank is like thin oil, has good fluidity and does not stick to the wall), which indicates that the first cleaning liquid, the second cleaning liquid and the third cleaning liquid have good cleaning effect on the sediment in the tank;
after the cleaning operation of sediment in the bottom of the crude oil storage tank is finished, pumping the mixture in the crude oil storage tank, and draining, and observing the thickness of the sediment on the wall of the crude oil storage tank by using an explosion-proof flashlight from a manhole of the crude oil storage tank;
Adding a second cleaning solution into the crude oil storage tank, namely, the liquid level of the crude oil storage tank is about 50%, injecting nitrogen into the tank by a nitrogen making machine, and stirring and cleaning sediment in the tank at intervals by a screw pump, namely, starting the screw pump for stirring once every 15min, wherein the stirring time is 3min each time, and cleaning for 3h in total;
The floating crude oil is recovered and then the water in the tank is emptied.
In the process, before the floating crude oil is recovered and water in the tank is drained, the explosion-proof flashlight is used for observing from a manhole of the crude oil storage tank, before the crude oil storage tank is cleaned, the sediment in the tank is black and sticky, but the cleaned crude oil storage tank wall is exposed out of the metal surface, most of the sediment is not present, a layer of crude oil floats on the water after cleaning, the water body is clear, and the first cleaning liquid, the second cleaning liquid and the third cleaning liquid have good cleaning effect on the sediment on the crude oil storage tank wall.
Note that the above is only a preferred embodiment of the present invention and the technical principle applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, while the invention has been described in connection with the above embodiments, the invention is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the invention, which is set forth in the following claims.
Claims (10)
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