KR20150140912A - Recycling method of sludge recovery oil - Google Patents

Abstract

The present invention relates to a method for recycling recovery oil including the following steps: a) collecting sludge settled in a crude oil tank; b) separating the sludge into the recovery oil, water, and sediments; and c) mixing the recovery oil with crude oil and performing a fractional distillation process. According to the method for recycling recovery oil of the present invention, limit on storage capability of the crude oil tank caused by settlement of the sludge can be eliminated by recycling the recovery oil separated from the sludge settled in the crude oil tank; drawbacks of the recovery oil, which are a high flow point, a low ignition point, and a high content of impurities, are eliminated; an effect of increasing profitability can be expected by performing the fractional distillation process; process costs for processing the sludge can be reduced; and costs for processing waste can be significantly reduced.

Description

Recycling method of sludge recovery oil [

The present invention relates to a recycling method of recovery oil. More particularly, the present invention relates to a recovery method of a recovery oil, which can recover recovery oil from sludge accumulated in a crude oil tank and then mix it with crude oil to recycle the recovery oil and expect profitability improvement effect.

In general, crude oil refers to petroleum as it is in its natural state, not processed or refined, and refers to a blackish brown sticky liquid mainly composed of various hydrocarbon compounds. Crude oil contains impurities such as sulfur, oxygen, nitrogen compounds, metals, moisture and gas components as well as hydrocarbon compounds as main components. These impurities are mixed with rust, naturally produced solid material, insoluble material, etc., generated from pipes or tank walls during the transfer of crude oil, and are formed into sludge and deposited on the lower part of the storage tank.

The crude oil storage tanks of refineries are obliged to undergo regular inspections every 8 to 10 years, though they vary from country to country due to the risk of oil spill due to leak. At this time, crude oil sludge Is cleaned and discharged. In addition, if oil spillage occurs in spite of these preliminary inspections, the sludge should be cleaned in order to repair the crude oil storage tank. In general, sludge accumulates in the crude oil storage tank because it is generated and accumulated at a high rate, and it reduces the space used in the tank. If it accumulates to the height of the crude oil outlet without being removed for a long time, it flows over the tank, ≪ / RTI > Particularly, when the level of the sludge is higher than the crude oil outlet, a large amount of sludge flows into the process for a moment, which causes problems such as a charge pump trip. In addition, when the sludge is introduced into the process, the lifetime of the heat exchanger in the process is shortened, the catalyst life is shortened, and the throughput loss due to the frequent filter operation of the catalyst process is adversely affected.

It is also important to remove the sludge from the tank, but it is also important to treat and dispose of it. Such sludge treatment methods include an incineration method, a physical refining method using a refinery or the like, a chemical refining method of treating sludge with isooxane and gas oil, and the like. In the recovery oil separated through the refining methods, And the content of impurities is high, there are restrictions on utilization. In addition, there are various restrictions on the operation of the process such as securing the reserve tank.

U.S. Pat. No. 04014780 (Mar. 29, 1977) United States Patent No. 05085710 (February 04, 1992)

As a result of repeated studies to solve the above problems, the inventors of the present invention have found that recovery oil recovered from sludge accumulated in a crude oil tank is mixed with crude oil and a disadvantage of recovery oil having high tie point, low flash point and high impurity content And to provide a recycling method of recovery oil that can expect profitability improvement effect.

The present invention relates to a recycling method of recovery oil. More specifically, the present invention relates to

a) recovering the sludge deposited in the crude oil tank;

b) separating the sludge into recovery oil, water and sediment; And

c) mixing the recovery oil with the crude oil and subjecting the oil to fractional distillation;

And recovering the recovery oil.

Further, step c) according to the present invention is more specifically

c1) a method in which recovery oil is mixed with crude oil using a line mixer and then transferred to a charge pump;

c2) a method in which recovery oil is periodically mixed with crude oil and transferred to a charge pump; And

c3) a method in which recovery oil is mixed with crude oil passed through a charge pump and transferred to a desalinator;

And the recovery oil may be mixed with the crude oil and the recovery oil.

The embodiment described above is not limited to the contents described above, and includes all matters that can be easily changed by a person engaged in the field. As an example, there may be cases where other types of devices are used for the purpose of implementing the same technique.

The recovery oil recycling method according to the present invention recovers the recovery oil separated from the sludge settled in the crude oil tank, thereby eliminating the storage limitation of the crude oil tank due to the accumulation of the sludge. In addition, the profitability improvement effect can be expected by overcoming the disadvantages of the recovery oil having a high tie point, a low flash point and an impurity content, and a fractional distillation treatment. Also, the sludge treatment can reduce the process cost, and the waste treatment cost can be greatly reduced.

1 to 3 show a recovery oil-crude oil mixing process according to an embodiment of the present invention.

Hereinafter, a method of recycling recovery oil according to the present invention will be described in detail with reference to the accompanying drawings. The following drawings are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the following drawings, but may be embodied in other forms, and the following drawings may be exaggerated in order to clarify the spirit of the present invention. Also, throughout the specification, like reference numerals designate like elements.

Hereinafter, the technical and scientific terms used herein will be understood by those skilled in the art without departing from the scope of the present invention. Descriptions of known functions and configurations that may be unnecessarily blurred are omitted.

First, a method of recycling recovery oil according to an embodiment of the present invention,

a) recovering the sludge deposited in the crude oil tank;

b) separating the sludge into recovery oil, water and sediment; And

c) mixing the recovery oil with the crude oil and subjecting the oil to fractional distillation;

. ≪ / RTI >

The crude oil used in the present invention refers to a flammable liquid existing in a natural state in the ground and having a brown to black color. Also, it may include various types of hydrocarbons and impurities, and these components may vary depending on the mined area and the type of hydrocarbons, but the present invention is not limited thereto.

Sludge deposited in the crude oil tank may vary in properties depending on the crude oil to be stored and the cleaning cycle. The method of recovering the deposited sludge may also vary. For example, in case of light oil, the amount of sludge is small and it is possible to wash with water. In the case of heavy oil, sludge and oil on the wall can be removed by dissolving in light oil. Also, in the case of bunker oil, since the sludge is solid at normal temperature, it is possible to dissolve and remove the solidified sludge at the bottom of the tank.

The sludge according to the present invention is not limited, but it can contain 5 to 28% by weight of water, and even in the case of pure sludge, that is, sediment, the content of asphaltene or inorganics can be 2 to 38% . Particularly, the foreign substance is composed mainly of iron (Fe), and the longer the storage time of the tank, the more the iron component due to corrosion of the tank can be increased. In addition, wax components, sand, other coke precursors, and the like may be further included.

Asphaltenes are insoluble in n-hexane and are soluble in toluene, which can precipitate as solid particles in crude oil to form sludge or form emulsions with heavy components such as resins and water. Particularly, in the case of sedimentation with solid particles, the asphaltenes existing in emulsion form are mixed with other crude oil or thermally separated, and the resin around the asphaltenes is separated and converted into a solid form.

In addition, the crude sludge may further contain water irrespective of the type of crude oil. The inclusion of such water forms a kind of film around the asphalt. Such membranes may cause the asphaltenes to crosslink three-dimensionally and other resins to become solvated, causing asphaltenes to form emulsions without phase separation with the crude oil components. Therefore, in the case of emulsion-like asphaltenes, it is the most difficult component to separate crude sludge and it is difficult to separate by centrifugation.

The step a) according to the present invention may be varied depending on the composition of the crude oil and the sludge. However, the step a) may be carried out by a filtration method using a filter or the like, a stirring method, a mechanical separation method such as a manual method (a method of discharging sludge from a tank using a person or a machine) , A heat separation method in which sludge is dissolved and pulverized by using heated crude oil or hot water, a solvent for dissolving sludge or a solvent extraction method for imparting fluidity to sludge by injecting a drug into a tank, a sound wave separation method and a chemical separation method Can be performed in more than one way.

Next, the recovered sludge can be recovered only by recovering recovery oil, water and sediment as in step b).

In the present invention, step b) is not limited to the separation method, and various methods can be selected depending on the composition of the sludge and the sludge removal method. For example, the sludge is allowed to stand at a temperature of 60 ° C or higher, preferably 60 to 130 ° C, such as Korean Patent No. 10-0475172, and the sediment and water can be phase-separated with the recovery oil. The reason for heating at this time is that the viscosity of sludge is lowered and the removal rate of sediments is improved. If necessary, an additive such as a dispersant may be further added. On the other hand, this process may be performed in a crude oil tank, or in a separate storage space connected to the crude oil tank. Or a method of heating the sludge to evaporate the recovery oil contained in the sludge as in JP-A-2012-229403, and then recovering the recovered oil by cooling.

According to an embodiment of the present invention, the recovered recovery oil may be recycled by mixing the recovery oil with the crude oil and subjecting it to fractional distillation treatment as in step c). More particularly, step c) of the present invention comprises:

c1) a method in which recovery oil is mixed with crude oil using a line mixer and then transferred to a charge pump;

c2) a method in which recovery oil is periodically mixed with crude oil and transferred to a charge pump; And

c3) a method in which recovery oil is mixed with crude oil passed through a charge pump and transferred to a desalinator;

The crude oil and the recovery oil may be mixed and subjected to fractional distillation treatment.

The double c1)

c1-1) mixing the recovery oil with crude oil using a line mixer; And

c1-2) transferring the crude oil mixed with the recovery oil to the charge pump;

As shown in FIG.

Referring to FIG. 1, recovery oil separated from water and sediments through phase separation can be mixed with crude oil passed through a charge pump as in (1), and then passed through a line mixer. The crude oil that has been thoroughly mixed with the recovery oil through the line mixer can be fed back to the charge pump and transferred to the Crude Distillation Unit (CDU) process as shown in ②. However, for more smooth mixing, the crude oil that has undergone the process of ② can be sent back to the process of ① for circulation. Also, the recovery oil can be continuously supplied during the circulation process, and the process of mixing the oil with the circulation and mixing through the line mixer can be continued.

It is also possible to mix the crude oil stored in the crude oil tank, rather than the crude oil charge tank, in the same manner. First, the recovered oil produced by phase separation can be mixed with the crude oil in the crude oil tank as in ③ and then passed through a line mixer. The crude oil sufficiently mixed with the recovery oil through the line mixer can be transferred to the crude oil tank again as shown in ④, and then transferred to the fractionation distillation process through the crude oil charge tank and the charge pump. Also, the crude oil mixed with the recovery oil of (4) can be circulated to the step (3) where it is mixed with the recovery oil. In this circulation process, the recovery oil can be continuously supplied, and the process of mixing with circulation and mixing through the line mixer can be continued.

The number of cycles in the c1) method according to the embodiment of the present invention is not limited, and the type, size, shape, and number of line mixers are not limited. For example, it is possible to adjust the flow rate inside the mixer by placing several members in the interior, and alternatively, a static mixer and a sulzer mixer may be alternately installed in the mixer.

Also, in the c1) method according to the embodiment of the present invention, the processes of (1) to (4) can be performed at the same time. In other words, recovery oil phase-separated from the sludge and crude oil from the crude oil tank can be mixed with ③ and passed through a line mixer to ④. The crude oil that has passed through the line mixer can be circulated in the same way as in the procedure (3) without being sent directly from the crude oil tank to the crude oil charge tank. In addition, the crude oil which has been passed through the process of ③ and ④ is transferred to the crude oil charge tank and the charge pump in the crude oil tank, and then sent to the front of the line mixer through the process of ① to mix again with the recovery oil. It can be sent to the front of the pump. Of course, even in this case, the crude oil passed through the charge pump can be recirculated through the process of (1) without being sent directly to the fractional distillation process.

The c2) method according to the embodiment of the present invention is a method of controlling the mixing period of the recovery oil when the crude oil and the recovery oil are mixed. In general, the recovery oil has a very high pour point, so it becomes solid when mixed with crude oil at room temperature. These solid recovery oils may not pass through the strainer used for impurity filtration at the charge pump front end.

The problem is that if the recovery oil is continuously mixed with crude oil, the strainer may be clogged by the recovery oil of the solid phase. According to the c2) method of the present invention, when the crude oil and the recovery oil are mixed, the supply period of the recovery oil is adjusted to eliminate the strainer clogging at the front end of the charge pump. That is, the solid recovery oil can remain in the strainer without passing through the strainer. However, only the crude oil passes through the strainer during the period when the recovery oil injection is stopped. Therefore, the recovery oil filtered by the strainer is washed by the flow of the crude oil, .

Referring to FIG. 2, step c2) will be described as follows. Recover the recovered recovery oil by mixing the sludge with the crude oil stored in the crude oil charging tank. At this time, the injection position of the recovery oil is the charge pump front end, and it can be mixed immediately without introducing the line mixer. The mixing cycle of the recovery oil can be freely modified depending on the composition of the sludge and recovery oil, the fluidity of the recovery oil, etc. However, it is possible to have a cycle of feeding the recovery oil for 0.5 to 3 hours and then stopping the supply of the recovery oil for 0.2 to 1 hour have. That is, it has a recovery oil supply interruption period of 0.2 to 1 hour in order to clean the residual recovery oil that can not pass through the strainer due to the injection of the recovery oil.

The method c3) according to the embodiment of the present invention is a method for securing the fluidity of the recovery oil by preheating the crude oil when the crude oil and the recovery oil are mixed.

Generally, when crude oil is fractionally distilled, it is divided into LPG, gasoline, naphtha, kerosene, light oil and heavy oil based on the boiling point by heating to 340 to 360 ° C. At this time, a heat exchanger (preheat exchanger) is installed to recover the heat energy applied to the distillation column to heat the crude oil before desalting. When crude oil is preheated through a heat exchanger, crude oil at room temperature or slightly above normal temperature is preheated to a temperature above 100 ° C. Since the preheating temperature is a temperature exceeding the pour point (70 DEG C) of the recovery oil, the recovery oil has a high fluidity immediately after mixing with the crude oil, so that the recovery oil can be uniformly mixed.

FIG. 3 illustrates a process c3) according to an embodiment of the present invention. The recovery oil, which is phase separated in the sludge, may be poured into crude oil passed through the preheater and mixed. At this time, the temperature of the crude oil passing through the preheater can be preheated to a temperature higher than the pour point of the recovery oil, and preferably, it can be preheated to a temperature of 90 to 150 ° C. In addition, the recovery oil may be injected periodically, such as c2) or continuously injected, and may be preheated again through the preheater after the crude oil passes through the desalinizer so that the recovery oil and the crude oil can be mixed more uniformly.

In the present invention, the recovery oil may be mixed in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of the crude oil. When the recovery oil is mixed more than 2 parts by weight, mixing with the crude oil is not smooth and it is difficult to secure the fluidity of the recovery oil. Because of the impurities in the recovery oil, the heating furnace, piping and other facilities are occluded, So that the process efficiency can be greatly reduced.

The method for recycling recovery oil according to the present invention may further include additives such as a neutralizing agent, an emulsifying agent, a metal decontamination agent, and a stabilizer depending on the case. In particular, if too much caustic is used, the fatty acid may stabilize the asphaltene-water mixture and interfere with the separation process. If the crude oil and water are mixed too strongly, an emulsion that is difficult to decompose may form, It is advisable to add a neutralizing agent and an anti-emulsifier which can control the stability of the mixture. Such an additive may be added in the middle of the process, and may be introduced at any stage within the range not impairing the object of the invention.

Also, the method of recycling recovery oil according to the present invention may further include mixing a condensate when mixing crude oil and recovery oil.

The condensate according to the present invention refers to a liquid hydrocarbon mixture having a carbon number of 1 to 7 obtained by condensing a gaseous mixture and condensing high-boiling substances by physical phase change. Condensate is a hydrocarbon with a low carbon number, so it has a low viscosity and can improve mixing efficiency between recovery oil and crude oil.

Hereinafter, a method of recycling the recovery oil according to the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following examples and comparative examples are merely examples for explaining the present invention in more detail, and the present invention is not limited by the examples and the comparative examples.

The composition and physical properties of the materials used in Examples and Comparative Examples are as follows.

(crude oil)

The properties and blending ratios of crude oil used in Examples are shown in Tables 1 and 2 below.

[Table 1]

[Table 2]

(Sludge and recovery oil after phase separation)

The characteristics of the recovery oil after the sludge and phase separation processes are shown in Table 3 below.

[Table 3]

 (Properties of mixed oil)

The properties of the mixed oil used in the examples were measured in the following manner.

① Sulfur: Total sulfur was measured by monochromatic wavelength-dispersive X-ray fluorescence (MWDXRF) spectrometry according to ASTM D7039 (Standard Test Method for Sulfur in Gasoline and Diesel Fuel by Monochromatic Wavelength Dispersive X-ray Fluorescence Spectrometry).

(2) Nitrogen: The sample was decomposed into gases by burning at 1,000 ° C using an elemental analyzer (EA-CHNS), and the thermal conductivity of these gases was measured to calculate the content.

(3) Micro-carbon residue (MCR): The amount of carbon residue remaining after evaporation and pyrolysis of the substrate was measured according to ASTM D450.

④ Metal content: The contents of iron, vanadium and nickel were measured using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometer).

⑤ Salinity: A salt analyzer was used according to ASTM D3230.

(yield)

The sample was measured using a gas chromatography flame ionization detector (GC-FID).

(Example 1)

1,400 tons of sludge collected in the crude oil charging tank was transferred to a centrifuge tank at 80 ° C for phase separation. Through the phase separation, water and sediment were separated separately from the sludge, and 1,000 tons of the remaining recovery oil was recovered.

Separately from the above, crude oil 1 in Table 1 stored in a crude oil charging tank was passed through a charge pump and mixed with recovery oil. The mixing amount is as shown in Table 4 below, and immediately after mixing, the mixture was passed through a line mixer to uniformly mix recovery oil and crude oil. The mixed oil was fed back to the charge pump and sent to the CDU process for fractional distillation. At this time, a sample of crude oil was sampled and the yield according to the nature of the crude oil and recovery oil mixed oil and the fractional distillation temperature was measured and described in Table 4 below.

(Example 2)

1,400 tons of sludge collected in the crude oil charging tank was transferred to a centrifuge tank at 80 ° C for phase separation. Through the phase separation, water and sediment were separated separately from the sludge, and 1,000 tons of the remaining recovery oil was recovered.

Separately from the above, crude oil 2 in Table 1 stored in a crude oil charge tank was passed through a charge pump and mixed with recovery oil. The mixing amount is as shown in Table 4 below, and immediately after mixing, the mixture was passed through a line mixer to uniformly mix recovery oil and crude oil. The mixed oil was fed back to the charge pump and sent to the CDU process for fractional distillation. At this time, a sample of crude oil was sampled and the yield according to the nature of the crude oil and recovery oil mixed oil and the fractional distillation temperature was measured and described in Table 4 below.

(Comparative Example 1)

The same procedure as in Example 1 was followed to fractional distillation except that the recovery oil was not mixed. At this time, a crude oil sample was taken and the yields according to the characteristic and fractional distillation temperatures were measured and are shown in Table 4 below.

(Comparative Example 2)

The procedure was as far as fractional distillation in the same manner as in Example 2, except that the recovery oil was not mixed. At this time, a crude oil sample was taken and the yields according to the characteristic and fractional distillation temperatures were measured and are shown in Table 4 below.

[Table 4]

As shown in Table 4, it can be seen that the crude oil subjected to the recycling method according to the present invention maintains a similar composition without increasing the components other than iron and salinity. However, the increase in the salinity content tended to increase the water retention time, but the decrease in the water retention efficiency was prevented by the injection of the antifoaming agent. In addition, the yield value is similar regardless of the temperature, and it can be seen that even when the recovery oil is mixed, it can be effectively recycled without affecting the properties and yield.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken in conjunction with the present invention. Therefore, the contents described in the embodiments are not intended to limit the scope of the present invention defined by the limitations of the claims.

Claims (9)

a) recovering the sludge deposited in the crude oil tank;
b) separating the sludge into recovery oil, water and sediment; And
c) mixing the recovery oil with crude oil and fractionally distilling the recovery oil;
And recycling the recovery oil. The method according to claim 1,
Wherein the step c) comprises mixing the recovery oil and the crude oil by one or more of the methods selected from the following c1) to c3).
c1) a method in which the recovery oil is mixed with crude oil using a line mixer and then transferred to a charge pump;
c2) a method in which the recovery oil is periodically mixed with crude oil and transferred to a charge pump; And
c3) a method in which the recovery oil is mixed with the crude oil passed through the charge pump and transferred to the desalter; 3. The method of claim 2,
The c1)
c1-1) mixing the recovery oil with crude oil using a line mixer; And
c1-2) transferring the crude oil mixed with the recovery oil to the charge pump;
And recycling the recovery oil. The method of claim 3,
And the crude oil passed through the step c1-2) is sent back to the step c1-1) to recycle the recovered oil. 3. The method of claim 2,
Wherein the recovery oil is supplied for 0.5 to 3 hours and then mixed with the recovered oil for 0.2 to 1 hour. 3. The method of claim 2,
Wherein the crude oil of c3) is preheated to a temperature equal to or higher than the pour point of the recovery oil. The method according to claim 6,
Wherein the crude oil is preheated to 90 to < RTI ID = 0.0 > 150 C. < / RTI > 3. The method of claim 2,
Wherein the recovery oil is mixed in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of the crude oil. The method according to claim 1,
Wherein the step a) is carried out by any one or two or more of the methods selected from mechanical separation, heat separation, solvent extraction, sound separation and chemical separation.

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