WO2012141024A1

WO2012141024A1 - Method for recovering oil fraction in crude oil sludge

Info

Publication number: WO2012141024A1
Application number: PCT/JP2012/058898
Authority: WO
Inventors: 均南口; 忠美毛利
Original assignee: システム機工株式会社
Priority date: 2011-04-14
Filing date: 2012-04-02
Publication date: 2012-10-18
Also published as: JPWO2012141024A1; JP5925189B2

Abstract

Provided are: a first step for introducing crude oil sludge into a vacuum vaporizing chamber (1); a second step for heating the crude oil sludge in the vacuum vaporizing chamber (1), stirring in a vacuum, and vaporizing the water and light oil fraction in the crude oil sludge; a third step for separating the water and light oil fraction by cooling the vaporized material obtained in the second step; and a fourth step for removing the vaporization residue in the vacuum vaporizing chamber (1) obtained in the second step from the vacuum vaporizing chamber (1), and separating the heavy oil fraction and the solid residue. Using this simple method, the oil fraction of the crude oil sludge can be recovered without requiring chemical injection or another similar pretreatment, and with substantially no water being admixed with the recovered oil fraction.

Description

Oil recovery method in crude oil sludge

The present invention relates to a method for recovering oil content in crude oil sludge accumulated at the bottom of a crude oil tank, for example.

Oil contained in crude oil sludge accumulated in a crude oil tank or the like is usually about 30 to 80% by weight, and there is a great need for oil recovery. Crude sludge treatment methods and treatment technologies include COW (Crude
Oil Washing) method, warm water washing method, chemical treatment method, manual method, and centrifugal separation method.

The COW method heats crude oil to approximately 60 ° C., pressurizes it, crushes and dissolves sludge accumulated at the bottom of the tank with an injection nozzle, and transfers it to another tank. Although crude sludge can be processed in a short period of time and has a lot of results, sludge is deposited again at the destination. For this reason, it can be said that it is a prescription for turning crude oil sludge. The COW method is a method of forcibly stirring uprooted sludge to make it temporarily fluid and recovering it to another tank, so there is a merit that sludge is not carried out of the tank. The problem has occurred and the problem is not essentially solved. Japanese Utility Model Laid-Open No. 6-81649 discloses a liquid ejecting apparatus used in the COW method.

The hot water washing method is a method that dissolves and floats crude sludge with hot water, and is a relatively safe treatment method, but it requires a large amount of hot water, so it is expensive, and oil that does not dissolve in hot water cannot be recovered. There are various problems such as emulsion generated by agitation and treatment of a large amount of waste water, and it is not so often used recently.

The chemical treatment method uses a chemical that dissolves sludge, but for reasons such as requiring heating and stirring operations, limited dissolution effects, and increased costs. This is rarely done recently.

The manual method has been practiced for a long time by a method in which an operator enters the tank and discharges it outside the tank with a manual or automatic excavator, and there are many places where it is still implemented. There are health, safety and global environment conservation (HSE) in recent years, especially safety issues. There is also a problem that the oil content of the discharged crude oil sludge is not recovered.

Any of the above methods has a big problem in terms of recovery of the oil content in the crude oil sludge, and is not an effective method. In this respect, the centrifugal separation method is a promising method in that, for example, a decanter type three-phase (solid matter, water, oil content) separator is used, and an oil content with little solid content or moisture content can be recovered. SEPTEMBER 2009 / STORAGE TERMINALS; pages 27 to 30 disclose that oil is recovered from crude sludge using a decanter type three-phase separator. JP-A-2004-243300 discloses a method for treating oil-water mixed sludge accumulated in a crude oil tank or the like. After the sludge is separated into a solid content and a liquid content by a centrifugal separator, an organic system is added to the liquid content. A method is disclosed in which a polymer flocculant is added to coagulate and precipitate oil suspended in a liquid in a suspended state.

Japanese Utility Model Publication No. 6-81649 JP 2004-243300 A (Claim 1)

However, centrifugation method using a three-phase separator of the decanter type, also the processing speed a large size is about 10 kL / hour, mass deposited in large tanks (typically 2000 m ³ or more) time to process Take it. In addition, it is difficult to feed from a crude oil tank to a centrifuge, and in many cases, it is necessary to feed more than twice the amount of sludge in order to stir and mix with fresh crude oil. In addition, pretreatment such as heating and injection of an emulsion breaker is necessary, and there is a problem that it is difficult to recover and oil is difficult to recover with a stable quality. In addition, it is difficult to completely separate solid sludge, oil, and moisture, and there is a problem that the recovered oil contains solids and, in many cases, at least about 2% of water. For this reason, it is a simple method that does not require pretreatment such as dilution of crude oil sludge and injection of emulsion breaker, etc., and can be directly treated, and the crude oil sludge with little water contamination in the recovered oil An oil recovery method has been desired.

Therefore, an object of the present invention is to provide an oil content recovery method for crude oil sludge that is a simple method, does not require pretreatment such as chemical injection, and has almost no water mixture in the recovered oil content.

In such a situation, the present inventor has intensively studied, and as a result, the crude oil sludge contains a water-in-oil emulsion phase, so that water is inevitably mixed in the recovered oil in the conventional centrifugal separation method. Water-in-oil emulsions in crude oil sludge can be easily broken by vacuum evaporation under specific conditions using a vacuum evaporation tank. Evaporated substances and evaporation residues obtained from the vacuum evaporation tank are easily separated from water by a simple separation method. The present inventors have found that oil can be recovered as oil components that do not contain oil, and have completed the present invention.

That is, the present invention includes a step of introducing crude oil sludge into the vacuum evaporation tank, and a step II of evaporating light oil and water in the crude oil sludge by heating and stirring the crude oil sludge in the vacuum evaporation tank under vacuum. And step III for cooling the vaporized substance obtained in step II to separate into light oil and water, and step IV for taking out the evaporation residue in the vacuum evaporation tank obtained in step II outside the vacuum evaporation tank And providing a method for recovering oil content in crude oil sludge.

According to the present invention, since the crude oil sludge is evaporated in a vacuum evaporation tank, a strong water-in-oil emulsion can be broken without using chemicals, and light oil from heavy substances and heavy oil from evaporation residues can be destroyed. Each can be recovered efficiently. In addition, since these recovered oil components hardly contain moisture, they can be recovered by blending with crude oil or the like as they are, and the environmental load can be greatly reduced. In addition, since the oil recovery rate is high, the needs for oil recovery can be satisfied with the recent rise in crude oil prices. Further, the heavy oil can be recovered and used together with solids or separated into heavy oil and solids and used individually as industrial fuel.

It is a flow figure which collects oil content from crude oil sludge.

In the present invention, as the crude oil sludge, sludge accumulated at the bottom of the crude oil tank outdoors, sludge accumulated at the bottom of the crude oil tank of the crude oil tanker, crude oil sludge exposed to the outdoors, crude oil sludge drifting the ocean or after drifting the ocean, Crude oil sludge berthed. Examples of sludge accumulated on the bottom of an outdoor crude oil tank include, for example, those deposited at a thickness of 500 to 2000 mm on the bottom of the tank during regular inspection after long-term use for 5 to 10 years. Crude oil sludge exposed to the open air is discharged into deserts that are larger than crude oil tanks by the conventional manual method, and is often found in oil producing countries such as the Caspian Sea coast and the Middle East. The crude oil sludge drifting in the ocean or the crude oil sludge docked after drifting includes, for example, an oily pollutant in which crude oil that has flowed into or out of the ocean due to an undersea oil field accident or a tanker accident and seawater are mixed. Such an oil pollutant is generally an emulsion produced by mixing crude oil and seawater, so it is an environmental pollutant called crude oil mousse. Compared with crude oil sludge accumulated in a crude oil tank, Although it has the same or similar composition, it has a high oil content and a low solid content.

Crude oil sludge contains asphaltenes, coke-like substances, oil and water. The oil content contained in the crude oil sludge is not particularly limited and is usually 20 to 80% by weight. Crude oil sludge may be diluted with crude oil. A coke-like substance is also called a coke precursor, and is a solid substance in which asphaltenes are condensed. The water content in the crude oil sludge is usually 10 to 30% by weight. Other substances contained in the crude oil sludge include those in which the wax content in the crude oil crystallizes and settles due to a decrease in temperature or the like, or inorganic substances such as iron and sand. In crude oil sludge, the amount of solids including asphaltene and coke is the remainder excluding oil and moisture.

Asphaltenes are a general term for petroleum components that are insoluble in n-hexane and soluble in toluene, and are solid components in crude oil alone. Asphaltenes include those that settle as solid particles and become sludge, and those that form an emulsion together with heavy components such as resin and moisture to settle and sludge.

Asphaltenes that settle as solid particles are those in which crude asphaltene particles are covered with resin (heavy oil) and exist stably in a colloidal form, mixed with different oil types such as light oil. In other cases, the resin is detached from the periphery of the asphaltenes due to a thermal history and settled as solid particles.

On the other hand, as described above, crude oil sludge contains about 10 to 30% by weight of water regardless of the crude oil type. For this reason, asphaltenes form a water-in-oil (W / O) emulsion that is stable and does not phase-separate with heavy components such as resins and moisture. This water-in-oil (W / O) emulsion is stable and does not phase separate because the film formed around the water droplets is stable. This is because the asphaltene is three-dimensionally cross-linked and the resin is solvated. This emulsion phase is extremely stable and is the most troublesome component in treating crude oil sludge and does not disappear by centrifugation or the like.

Thus, crude oil sludge is a complex mixture of asphaltene particles, coke-like substances, water-in-oil emulsion, wax crystallized product, etc., and interacts with each other such as aggregation, emulsion, and gelation. In addition, although crude oil sludge is deposited at the bottom of the tank, for example, it is mixed with oil, so what method should be used to separate the crude oil sludge from the oil when discharging it to the outside of the tank? However, the oil and sludge are mixed in order to provide fluidity, and the oil is generally contained in a large amount such as 80% by weight at maximum. For reference, the properties of crude oil sludge accumulated in crude oil tanks of petroleum companies are shown in Table 1. In Table 1, the heptane-insoluble fraction is soluble in the fraction (oil) up to the resin, and asphaltene is insoluble. The benzene insoluble matter is soluble up to asphaltenes, and the insoluble matter is mud moisture, minerals and coke-like substances. The coke-like substance is a main component of benzene insoluble matter. It should be noted that the toluene-insoluble component and the benzene-insoluble component are considered to be substantially the same substance because both solvents have substantially the same solubility. The oil content is a calculated value, which is 100- (heptane insoluble content)-(water content), and the asphaltene is a calculated value, (heptane insoluble content)-(benzene insoluble content).

Next, an example of a method for recovering the oil content in the crude oil sludge according to the present invention will be described with reference to FIG. Step I is a step of introducing crude oil sludge into a vacuum evaporation tank. In FIG. 1, reference numeral 21 denotes a crude oil sludge accumulated at the bottom of the crude oil tank transferred from the crude oil tank, a crude oil sludge left unattended in the field, and an oily pollutant that drifts or shores in the ocean (crude oil mousse). ) Are collected and transferred and stored in the crude oil sludge storage tank 2. Note that crude oil sludge and the like deposited on the bottom of these crude oil tanks may be directly transferred to the vacuum evaporation tank. The method of introducing the crude oil sludge into the vacuum evaporation tank is not particularly limited, and a method of automatically conveying the crude oil sludge 21 heated by the heater 22 and having fluidity by the screw pump 3 or the like is mentioned.

Step II is a step of evaporating light oil and water in the crude oil sludge 21 by heating and stirring the crude oil sludge in the vacuum evaporation tank 1 under vacuum. Conventionally, the vacuum evaporation method is used for drying waste containing a large amount of water, such as waste food or excess sludge, or for obtaining dry food. Further, a decompression process such as distillation of petroleum under reduced pressure using a vacuum distillation apparatus or the like is also known. Both are aimed at efficient evaporation with reduced boiling points of water and oil under reduced pressure. On the other hand, the present invention aims to break the emulsion in the raw material, and is an operation in which oil is contained in the evaporating substance and the evaporation residue, respectively, which is greatly different from the conventional vacuum evaporation method.

The vacuum evaporation tank 1 having the stirring blades 11 is preferable in that the crude oil sludge can be stirred uniformly. The vacuum evaporation tank 1 has means for heating the crude oil sludge in the vacuum evaporation tank 1 to a constant temperature. In this example, the vacuum evaporation tank 1 has an outer heating space (jacket) 12 and is heated through steam 9 generated in a boiler. Moreover, the inside of the rotating shaft which comprises the axis | shaft of the stirring blade 11 may be made into a hollow structure, and the vapor | steam 9 which generate | occur | produced with the boiler may be passed through the inside. Thereby, a heat transfer area can be increased further. Moreover, the vacuum evaporation tank 1 has decompression means such as a vacuum pump 7 for decompressing the inside of the tank. The decompression means is not limited to a vacuum pump, and for example, an ejector can be used. Further, the vacuum evaporation tank 1 has a crude oil sludge inlet 13, an evaporated substance outlet 14 connected to the aggregator 4, and an evaporation residue outlet 15 connected to the heavy oil separator 8. In FIG. 1, symbol E ₁ indicates the exhaust of the vacuum pump.

After the step I, the inlet valve 16 and the distillation residue take-off valve 17 of the vacuum evaporation tank 1 are closed, and the condenser 4 and the light oil separator 6 are sealed in the system, and the vacuum pump 7 is operated to evacuate the system. Reduce pressure. Further, steam flows through the outer heating space 12 of the vacuum evaporation tank 1 to heat the crude oil sludge 21.

In step II, the heating and vacuum conditions are such that the evaporated substance of the crude oil sludge 21 contains moisture and some oil. Some oil components are light oil components that evaporate with the evaporation of moisture. The light oil has a boiling point of up to 250 ° C. under atmospheric pressure and particularly up to 200 ° C. under atmospheric pressure. Specific examples of the heating and vacuum conditions include a heating temperature of 70 to 150 ° C., preferably 70 to 130 ° C., and a degree of vacuum (gauge pressure) of −80 to −100 KPa, preferably a degree of vacuum (gauge pressure) of −90 to − 100 KPa. Under such heating and vacuum conditions, water in the crude oil sludge can be surely evaporated and the emulsion can be extinguished. Also, the light oil other than water was entrained as an evaporating substance because the water was surely evaporated, and the water and light oil that did not form an emulsion were easily and reliably placed by means such as standing after condensation. This is because they can be separated. On the other hand, evaporating only the moisture from the crude oil sludge requires a delicate operation, and even if only the moisture is evaporated, it is not easy to remove a trace amount of light oil that is inevitably mixed.

In Step II, the amount of light oil to be evaporated varies depending on the amount of light oil contained in the crude oil sludge and cannot be determined unconditionally. However, it is approximately 5% by weight or more, preferably 10% by weight to the oil content of the crude oil sludge. 50% by weight. If the amount of the light oil to be evaporated is too small, the evaporation of water becomes insufficient and the emulsion may not be completely extinguished. On the other hand, when the amount is too large, the heating temperature and the degree of vacuum are increased more than necessary, which is not efficient. On the other hand, if the lower limit value of the amount of light oil to be evaporated is the above value, the water is sufficiently evaporated and the emulsion can be completely extinguished.

The stirring of the crude oil sludge in the step II is carried out in order to uniformly heat and promote the evaporation of the evaporated substance in the crude oil sludge. The stirring speed (rotational speed) is not particularly limited, but may be about 2 to 30 revolutions / minute. With such a stirring speed, the evaporation of the evaporating substance in the crude oil sludge can be sufficiently promoted.

In step II, with the heating and decompression of the vacuum evaporation tank 1, evaporation of light oil such as gasoline in the crude oil sludge starts, and the water forming the emulsion also evaporates. The emulsion disappears due to the evaporation of moisture.

Step III is a step in which the evaporated substance obtained in Step II is cooled and separated into light oil and water. A known condenser 4 may be used for cooling the evaporating substance. The refrigerant 5 for cooling the condenser 4 is not particularly limited, and examples thereof include water such as seawater and industrial water and known refrigerants other than water. The condensed material condensed by the condenser 4 is separated into a light oil component and water by stationary separation in the light oil component separator 6, and the light oil component is recovered. The light oil separator 6 can use, for example, a known gravity type oil-water separation. The light oil separator 6 of this example is divided into two chambers by a baffle plate 61 having a predetermined height lower than the internal height, and allows the condensed material 621 to flow into one chamber 62. The condensate 621 flowing into the chamber 62 is a mixture of light oil and water and does not become an emulsion, but is completely separated vertically. Light oil components having a specific gravity lighter than water, which is statically separated in one chamber 62, flow into the other chamber 63 by overflowing from the chamber 62. For this reason, the light oil component 622 recovered in the other chamber 63 is hardly mixed with water, and is usually 0.5% by weight or less, particularly 0.3% by weight or less, and further 0.1% by weight or less. Amount. The light oil component 622 accumulated in the chamber 63 is recovered from the light oil component outflow pipe 65 (reference numeral P _{1 in} FIG. ₁ ). The separated water remaining in one chamber 62 may be drained by opening the drain valve 64 (symbol P _{2 in} FIG. 1). The light oil separator 6 may have a one-chamber structure without a baffle plate. When the light oil separator 6 has one chamber, a light oil recovery pipe or the like may be installed near the center of the light oil separator 6 in the height direction. Steps II and III proceed almost simultaneously.

The II process is completed when the evaporation of the water in the crude oil sludge almost stops and the operation of the vacuum pump 7 is stopped. Whether or not the evaporation of moisture in the crude oil sludge has been stopped can be determined by observing the level gauge of the light oil content separator 6. That is, when the oil-water interface (water level) of the liquid level gauge does not change with time, it can be determined that the evaporation of moisture has stopped. Further, by observing the rising tendency of the temperature in the vacuum evaporation tank 1, it can be determined that the evaporation of moisture has stopped. That is, in the vicinity of the end of the step II, the evaporation substance in the vacuum evaporation tank 1 decreases, and the heating proceeds while the internal temperature of the vacuum evaporation tank 1 rises.

After the operation of the vacuum pump 7 is stopped, the decompression release valve 71 is further opened to send the atmosphere into the system so that the system is at atmospheric pressure. The evaporation residue in the vacuum evaporation tank 1 consists of a solid content and heavy oil content containing asphaltenes and coke-like substances, and the emulsion in the evaporation residue disappears and contains almost no water. The heavy oil is an oil that is heavier than the light oil in the evaporated substance. Further, the evaporation residue after Step II is high temperature and has sufficient fluidity. After completion of step II and step III, step IV is performed.

Step IV is a step of taking out the evaporation residue in the vacuum evaporation tank obtained in Step II, and is preferably a step of separating the extracted evaporation residue into a heavy oil and a solid residue. . In order to take out the evaporation residue in the vacuum evaporation tank 1 to the outside of the vacuum evaporation tank 1, the valve 17 installed in the middle of the pipe connecting the vacuum evaporation tank 1 and the heavy oil separator 8 may be opened. Thereby, the evaporation residue in the vacuum evaporation tank 1 flows into the heavy oil separator 8 by gravity. That is, the evaporation residue in the vacuum evaporation tank 1 is taken out of the vacuum evaporation tank in a fluidized state.

The evaporation residue is separated into an oil and a solid in the heavy oil separator 8. The heavy oil separator 8 is not particularly limited as long as it can separate a mixture (fluid) of oil and solids by standing, and a known separator can be used. In this example, the inside of the heavy oil separator 8 is divided into three chambers by two

baffle plates

81 and 82 that are lower than the inner height and different in height, and three

chambers

83, 84, 85 having different heights are divided. Are sequentially adjacent. That is, the evaporation residue 831 flows into the chamber 83 having a height. The evaporation residue that has flowed into the chamber 83 is a mixture of heavy oil and solids, and since there is no moisture, there is no emulsion and it is completely separated vertically. The heavy oil component that has been allowed to stand and separate in the chamber 83 and a part of the solid content flow into the adjacent chamber 84 as it overflows from the chamber 83. In addition, the heavy oil that has been allowed to stand and separate in the chamber 84 flows into the adjacent chamber 85 as it overflows from the chamber 84. The heavy oil recovered in the most downstream chamber 85 contains almost no moisture, and is usually 1.5% by weight or less, particularly 1.0% by weight or less, and further 0.5% by weight or less. It is. The heavy oil collected in the chamber 85 is recovered from the heavy oil outflow pipe 87 (reference numeral P _{3 in} FIG. 1). Incidentally, the solid content after separation remaining in the chamber 83 may be discharged by opening the discharge valve 86 (code P ₄ in FIG. _1). The solid content contains asphaltene and heavy oil and can be used as a fuel. If the solid content is used as boiler fuel for generating the heating vapor in the vacuum evaporation tank 1, the oil recovery cost can be reduced. The heavy oil separator 8 is not limited to the above three chambers, and may be one chamber, two chambers, or four or more chambers. When the heavy oil separator 8 has one chamber, a heavy oil recovery pipe or the like may be installed in the vicinity of the center of the heavy oil separator 8 in the height direction. If it is required that the remaining amount of solids in the heavy oil is very small, the heavy oil and solids mixture can be further separated by a filter or centrifuge using a metal filter. Also good.

In the present invention, there are a step of recovering the light oil separated in the step III and a step of recovering the heavy oil separated in the step IV. That is, the light oil separated and recovered in the step III and the heavy oil separated and recovered in the step IV are mixed and recovered, or individually recovered without mixing. The recovered mixed oil or light oil and heavy oil may be returned to, for example, a crude oil tank. According to the oil recovery method of the present invention, since no chemicals are used, processing such as chemical recovery is unnecessary, and the environmental burden can be greatly reduced. In addition, the need for oil recovery can be satisfied with the recent rise in crude oil prices.

In the case of crude sludge having a low solid content such as crude oil mousse, the evaporation residue in the vacuum evaporation tank is simply taken out of the vacuum evaporation tank as it is in the IV process. Since crude mousse has a high oil content and a low solid content, it is efficient to recover the solid content and heavy oil without separating them. For example, the recovered heavy oil containing a small amount of solids may be returned to the crude oil tank.

The oil recovery method in the crude oil sludge of the present invention is a continuous process or a discontinuous process. The continuous process is a method of continuously carrying out the steps I to IV described above, and some of the steps may be performed simultaneously, for example, steps II and III. In addition, a discontinuous process means that there is a discontinuous part (idle time) that cannot be said to be continuous, for example, at one or more between steps I and II, between steps II and III, and between steps II and IV. Say how to do. An all discontinuous process refers to a batch process. Either the continuous process or the discontinuous process has the effect of the present invention.

Next, an example of a continuous process in the method for recovering oil in crude sludge according to the present invention will be given. Crude oil sludge is heated in the storage tank 2. Crude oil sludge fluidized by heating is continuously charged into the vacuum evaporation tank 1 by a screw pump 3 or the like (Step I). In the vacuum evaporation tank 1, all the operations of heating, vacuum and stirring are performed continuously at the same time. Thereby, the evaporation of moisture and light oil continuously proceeds (step II), and the moisture and light oil are continuously sent to the condenser 4. Also in the step III, the evaporated substance obtained in the step II is continuously cooled and condensed, and the light oil component and water are continuously separated in the light oil component separator 6 and discharged to the outside. Also in the IV process, the evaporation residue is continuously discharged from the vacuum evaporation tank 1. Further, when the separation step is performed in the IV step, the continuously discharged evaporation residue is also continuously separated into a heavy oil component and a solid component by the heavy oil separator 8.

In the case of a continuous process, the crude oil sludge inlet 13 and the evaporation residue outlet 15 to the vacuum evaporation tank 1 should be installed at a site as far as possible (particularly horizontal distance). It is preferable in that it is possible to prevent the crude oil sludge being charged from being short-circuited and mixed into the evaporation residue and discharged from the vacuum evaporation tank 1 while being insufficiently evaporated. The processing retention time (retention time) of the crude oil sludge in the vacuum evaporation tank 1 varies depending on the operating conditions such as the degree of vacuum and temperature, and therefore cannot be determined in general. This is preferable in that vacuum evaporation is performed.

In the present invention, the recovery rate of the total oil content from the crude oil sludge, that is, the total oil content with respect to the oil content in the raw material charged in the vacuum evaporation tank is almost 100%. Therefore, it can be recovered at approximately 98%. The water content in the total oil, which is the sum of the recovered light oil and heavy oil, is usually less than 1.0% by weight, preferably 0.5% by weight or less. The recovered oil may be recovered as a mixture of light oil and heavy oil, or the heavy oil may be recovered as a mixture together with the solid. A mixture of heavy oil and solids can be used as an industrial fuel.

Next, the present invention will be described more specifically with reference to examples. However, this is merely an example and does not limit the present invention.

Using a vacuum evaporation tank for testing with the following specifications, a light oil separator and a heavy oil separator, each with a simple chamber separator, and recovering oil in crude oil sludge A under the following operating conditions went. That is, the crude oil sludge A was introduced into the vacuum evaporation tank A and heated and stirred under vacuum to evaporate the light oil and water in the crude oil sludge A (Step I and Step II). Next, the evaporated substance was cooled and separated into light oil and water, and the light oil was recovered (step III). On the other hand, with the end of generation of the condensed liquid, the operation of the vacuum evaporation tank A was stopped, the vacuum state was returned to atmospheric pressure, and the residue was discharged from the lower part of the vacuum evaporation tank to the heavy oil separator. And the heavy oil isolate | separated with the heavy oil content separator was collect | recovered.

As a result, 8.2% by weight of a light oil having a specific gravity of 0.770 was recovered from the light oil separator. No moisture was detected in this light oil. On the other hand, 20.6% by weight of heavy oil having a specific gravity of 0.950 to 0.990 was recovered from the heavy oil separator, and 48.1% by weight of the separation residue was recovered. The water content in this heavy oil was 0 (zero) wt%. The separation residue was mostly solid and contained a small amount of heavy oil. The amount of oil recovered from the crude oil sludge A was 98% (28.8% by weight / 29.3% by weight).

(Vacuum evaporation tank and operating conditions)
・ Vacuum evaporation tank A shown in FIG.
・ Average rotation speed of stirring blades: 20 rotations / minute ・ Vacuum degree: −96 kPa, heating temperature (raw material temperature): 80 to 120 ° C.
Evaporative material temperature (condenser inlet temperature): 50 to 85 ° C
・ Batch treatment: Raw material 47.8 kg, treatment for 2 hours ・ Crude oil sludge A: Moisture 22.9 wt%, oil content 29.3% wt, solid content 47.8 wt%
(Related equipment)
・ Heating means: Jacket system with steam heating from outside ・ Vacuum pump; Water seal type ・ Condenser: Cooling water used

The same method as in Example 1 was performed except that the following vacuum evaporation tank and operating conditions were used. As a result, 5.1% by weight of light oil having a specific gravity of 0.790 was recovered from the light oil separator. The water content in this light oil was 0.1% by weight or less. On the other hand, 13.1% by weight of heavy oil was recovered from the heavy oil separator, and 60.1% by weight of separation residue was recovered. The water content in the heavy oil was 1.0% by weight. The recovery rate as a liquid oil from crude oil sludge B was 58% by weight (18.2% by weight / 31.6% by weight). In addition, a part of heavy oil content is contained in the separation residue, and if the solid content or a mixture of the solid content and the heavy oil is used as the fuel, the recovery rate as an energy source is close to 100%.

(Vacuum evaporation tank and operating conditions)
・ Vacuum evaporation tank B shown in Fig.1
・ Average speed of stirring blades: 20 revolutions / minute ・ Vacuum degree: −100 kPa, heating temperature (raw material temperature): 75 to 97 ° C.
・ Evaporation substance temperature (condenser inlet temperature): 45-50 ℃
・ Batch treatment: Raw material 41.2 kg, treatment for 5 hours ・ Crude oil sludge B: Moisture 20.4 wt%, oil content 31.6 wt%, solid content 48.0 wt%

The same method as in Example 1 was performed except that the following vacuum evaporation tank and operating conditions were used. As a result, 9.2% by weight of light oil was recovered from the light oil separator. The water content in this light oil was 0.1% by weight or less. On the other hand, 13.4% by weight of heavy oil was recovered from the heavy oil separator, and 56.2% by weight of separation residue was recovered. The water content in the heavy oil was 1.0% by weight. The recovery rate as a liquid oil from crude oil sludge C was 64% by weight (22.6% by weight / 35.3% by weight). In addition, a part of heavy oil content is contained in the separation residue, and if the solid content or a mixture of the solid content and the heavy oil is used as the fuel, the recovery rate as an energy source is close to 100%.

(Vacuum evaporation tank and operating conditions)
・ Vacuum evaporation tank A shown in FIG.
・ Average rotation speed of stirring blades: 20 rotations / minute ・ Vacuum degree: −94.3 kPa, heating temperature (temperature in the tank): 124.9 ° C.
・ Evaporation substance temperature (condenser inlet temperature): 58-80 ℃
・ Batch treatment: Raw material 44.7 kg, treatment for 2 hours ・ Crude oil sludge C: Moisture 21.0 wt%, oil content 35.3% wt, solid content 43.7 wt%

According to the present invention, since the recovered oil content hardly contains any water, it can be recovered by blending it with crude oil or the like as it is. The amount of crude oil sludge accumulated in a huge crude oil tank over a long period of time is large, and the oil recovered from it becomes a valuable resource under the recent rise in crude oil prices. In addition, since no chemical is used, secondary processing such as chemical processing becomes unnecessary, and the environmental load can be reduced.

Crude oil and heavy oil spilled into the ocean, while drifting into the ocean, are affected by wind and waves, and heavy components such as asphaltene are mixed with seawater to form an emulsion. It causes great environmental pollution around the ocean and coast. In the past, oil pollutants that drifted or shored in the ocean were often treated as waste without collecting the oil, and in extreme cases, the drifting oil pollutants settled on the seabed with chemicals. For a long period of time, it caused enormous environmental pollution. On the other hand, the oil content recovery method of the present invention can treat such an oil pollutant as it is without using chemicals and can be separated into an oil content and a solid content, thereby reducing the waste treatment burden, Contributes greatly to global environmental conservation.

DESCRIPTION OF SYMBOLS 1 Vacuum evaporation tank 2 Crude oil tank or crude oil sludge storage tank 4 Condenser 6 Light oil separator 7 Vacuum pump 8 Heavy oil separator 10 Oil recovery apparatus in crude oil sludge

Claims

I process for introducing crude oil sludge into the vacuum evaporation tank;
II step of evaporating light oil and water in the crude oil sludge by heating and stirring the crude oil sludge in the vacuum evaporation tank under vacuum;
A step III in which the evaporated substance obtained in step II is cooled and separated into light oil and water;
And a step IV of taking out the evaporation residue in the vacuum evaporation tank obtained in the step II to the outside of the vacuum evaporation tank, and a method for recovering oil in crude oil sludge.
Crude oil sludge accumulated at the bottom of an outdoor crude oil tank, sludge accumulated at the bottom of a crude oil tank of a crude oil tanker, crude oil sludge exposed to the outdoors, crude oil sludge drifting in the ocean, or crude oil sludge docked after drifting in the ocean The method for recovering oil in crude oil sludge according to claim 1, wherein:
The method for recovering oil content in crude oil sludge according to claim 1 or 2, wherein the crude oil sludge contains asphaltene, coke-like substance, oil and water.
The method for recovering oil content in crude oil sludge according to any one of claims 1 to 3, wherein the crude oil sludge contains a water-in-oil emulsion phase.
The crude oil sludge according to any one of claims 1 to 4, wherein the oil in the evaporated substance obtained in the step II is a light oil up to a boiling point of 250 ° C (under atmospheric pressure). Oil recovery method.
The oil content in the crude oil sludge according to any one of claims 1 to 4, wherein the step II has a heating temperature of 70 to 150 ° C and a degree of vacuum (gauge pressure) of -85 to -100 KPa. Collection method.
The method for recovering oil content in crude sludge according to any one of claims 1 to 6, wherein in step III, the condensate condensed by cooling is allowed to stand and be separated into light oil and water.
The method for recovering oil in crude oil sludge according to any one of claims 1 to 7, wherein in the step IV, the evaporation residue in the vacuum evaporation tank is taken out of the vacuum evaporation tank in a fluidized state.
9. In the step IV, the removed fluid is separated into a heavy oil and a solid, or separated into a heavy oil and a mixture of the heavy oil and the solid. Oil recovery method for crude oil sludge.
10. The method for recovering oil content in crude oil sludge according to claim 9, comprising a step of recovering the light oil component separated in the step III and a step of recovering the heavy oil component separated in the step IV.
The method for recovering oil content in crude oil sludge according to any one of claims 1 to 10, wherein the process is a continuous process or a discontinuous process.