JP2018039005A - Processing method of crude oil-containing waste liquid and processing facility of crude oil-containing waste liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method of a crude oil-containing waste liquid capable of effectively and surely separating and recovering crude oil and water of the crude oil-containing waste liquid in short time, and a processing facility thereof.SOLUTION: There is provided a processing method of a crude oil-containing waste liquid having an addition process for adding a coagulant to the crude oil-containing waste liquid, a heating process for heating the waste liquid during or after addition either, and a centrifugation process for centrifuging the waste liquid to which the coagulant is added to separate three components of an oil component, water and a solid. For reducing moisture content of recovered oil, an emulsion breaker is added before conducting the centrifugation process. A polyamine-based coagulant is included as the coagulant.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for treating crude oil-containing waste liquid and a treatment facility used therefor, and is suitable for use in the treatment of waste liquid discharged from a washing process of a crude oil storage tank.

Crude oil imported from abroad is temporarily stored in a crude oil tank and sent to the refining process as needed. The tank used for storage needs to be inspected regularly. At that time, all the stored crude oil is drawn out and the inside of the tank is washed. As a tank cleaning method, a Crude Oil Washing method (hereinafter referred to as “COW”) in which sludge accumulated in the tank is washed with heated crude oil is widely applied. After the COW is carried out, a washing waste liquid called “warm water washing SLOP” in which sludge and water are mixed with crude oil is discharged by washing with warm water.
The hot water washing SLOP contains sludge accumulated in the crude oil tank and high boiling point hydrocarbons such as wax and asphaltene contained in the crude oil. Moreover, since the sludge remaining in the tank is also contained in the hot water washing SLOP, it is desirable to separate and treat these by an appropriate treatment in order to treat this.
On the other hand, since the oil contained in the warm water washed SLOP is derived from crude oil, it is desirable to recover and refine it for effective use of resources. However, since oil containing moisture and sludge cannot be supplied as it is to the crude oil refining process, it is desirable that the sludge and water content of the recovered oil be as low as possible.

  The crude oil refining process is not originally intended to process crude oil containing a large amount of water, but treats a large amount of crude oil-containing waste liquor with a high water content, such as warm water washed SLOP, in which sludge and water are mixed with crude oil. If an attempt is made, problems such as corrosion of the refining equipment may occur due to the influence of water, salts, etc. contained in the hot water cleaning SLOP. For this reason, the hot water cleaning SLOP is processed little by little, and there is a problem that the untreated hot water cleaning SLOP must be stored in the storage tank for a long period of time. For this reason, development of the equipment which can process hot water washing SLOP in large quantities was calculated | required.

  In order to meet these demands, various oil / water separation methods have been proposed. For example, an oil-water separation device called API that floats oil by supplying oil-containing wastewater to a water tank having a certain residence time by utilizing the specific gravity difference between water and oil, and CPI using an inclined plate has been put into practical use. Yes.

However, in the oil-water separator using such a difference in specific gravity, there is a problem that it is necessary to retain wastewater for a long time in the apparatus for the separation, which increases the size of the apparatus and increases the processing time. In addition, oil and water contained in the warm water washing SLOP are stable in the presence of oil droplets in water and oil droplets in oil due to the presence of a surface active component in wax and crude oil and floating substances. There is a case. In such a state, there is a problem that it is difficult to sufficiently separate oil and water by the separation method using the specific gravity difference.
In this respect, if a centrifuge is used, oil-water separation can be performed in a short time. For example, Patent Document 1 discloses a method in which oil containing water is supplied to a centrifuge and water and oil are separated in a short time.
Patent Document 2 also discloses a method of separating water and sludge from oil containing water by centrifugation. The oil-water separation method using such a centrifugal separator has an advantage that it can be performed in a relatively short time compared to oil-water separation based on a difference in specific gravity.
Furthermore, in Patent Document 3, an anionic surfactant and an inorganic flocculant are added to oil-containing wastewater, and after forming a floc of oil in advance, a nonionic surfactant is added and centrifuged to separate water from oil. A method for separating sludge has been proposed.
Moreover, although patent document 4 describes the oil-water separation technique by centrifugation as a background art, it is pointed out as a subject that the moisture content of the oil collect | recovered by this technique is high.
Furthermore, Patent Document 5 discloses a method for removing solids and salt from crude oil containing solids and salt. That is, warm water is added to crude oil, and after adding an emulsion breaker, they are mixed well with a stirrer. Thereafter, the oil component, water, and solid content that are desalted from the mixed solution in the stationary separation tank are separated. However, static separation tanks leave the mixed liquid to be treated and separate it using the specific gravity difference between oil, water, and solids. And need to increase water area

JP 2006-104233 A JP-A-2015-199848 JP 59-112808 A JP 2012-229403 A Japanese Patent No. 4679680

However, when crude oil forms an emulsion in the warm water washed SLOP, it may be difficult to separate water and oil by the separation method using a centrifuge. Even in the tests conducted by the present inventors, even if the hot water washed SLOP is simply centrifuged by the method of the above-mentioned patent document, the water and the oil may not be separated, and the centrifugation that completes the oil-water separation in a short time. Therefore, there has been a demand for a more reliable method for oil-water separation treatment of crude oil-containing waste liquor that takes advantage of these characteristics.
Moreover, although various methods have been proposed for separating water and oil using centrifugal separation, the water content of recovered oil is still high, and further reduction has been desired. For this reason, when oil was separated and refined from the hot water washing SLOP using a centrifuge, further reduction of the moisture content was desired.

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to efficiently separate and recover oil and water from a crude oil-containing waste liquid such as warm water washed SLOP efficiently and in a short time. An object of the present invention is to provide a method of treating crude oil-containing waste liquid and its treatment equipment.

The method for treating a crude oil-containing waste liquid according to the present invention includes an addition step of adding a flocculant to a waste liquid containing crude oil, and adding the waste liquid at least one of before, during, and after the addition of the flocculant. It is characterized by having a heating step for heating and a centrifugation step for separating the waste liquid to which the flocculant has been added into three components of oil, water and solid matter.
Furthermore, the crude oil-containing waste liquid treatment facility according to the present invention includes an addition facility for adding a flocculant to a waste liquid containing crude oil, a heating facility for heating the waste liquid, and the flocculant being added. A centrifuge for separating the heated waste liquid into oil, water and solids is provided.
Furthermore, another crude oil-containing waste liquid treatment facility of the present invention is a waste fluid treatment facility containing crude oil, an addition facility for adding a flocculant and an emulsion breaker to the waste liquid, and heating the waste liquid. And a centrifuge for separating the heated waste liquid into oil, water and solids, to which the flocculant and the emulsion breaker are added.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to isolate | separate the crude oil, the water, and solid substance in a crude oil containing waste liquid efficiently and reliably in a short time. In addition, by separating crude oil from water and solids, it is possible to recover crude oil in crude oil-containing waste liquid that has been difficult to reuse and use it as a resource.

It is a schematic diagram of the processing equipment of the crude oil containing waste liquid of Embodiment 1. It is a schematic diagram of the processing equipment of the crude oil containing waste liquid of Embodiment 2. It is a schematic diagram of the processing equipment of the crude oil containing waste liquid of Embodiment 3. It is a schematic diagram of the hot water washing | cleaning SLOP processing equipment of Embodiment 4 and Example 4. FIG. FIG. 10 is a schematic diagram of a crude oil-containing waste liquid treatment facility according to a fifth embodiment. It is a figure which shows the state of the hot water washing | cleaning SLOP after the centrifugation of Examples 2, 3 and Comparative Examples 1,2. It is a graph which shows the relationship between the emulsion breaker addition rate in Example 4, and the moisture content of recovered oil. It is a graph which shows the relationship in the temperature in Example 4, and the moisture content of the collection | recovery oil.

As a result of intensive research to solve the above-mentioned problems, the present inventor has added a flocculant to the waste liquid prior to oil-water separation of the crude oil-containing waste liquid using a centrifuge, and the oil-water separation can be achieved in a short time. The present inventors have found that it can be performed efficiently and reliably and have completed the present invention.
That is, the method for treating a waste liquid crude oil-containing waste liquid according to the present invention includes an addition step of adding a flocculant to a waste liquid containing crude oil, and the waste liquid at least one of before, at the time of, and after the addition of the flocculant. And a centrifugal separation step of separating the waste liquid to which the flocculant has been added into three components of oil, water and solids by centrifugation.

  Here, the aggregating agent refers to an additive added to agglomerate particles or oil droplets in the crude oil-containing waste liquid, and examples thereof include a polymer aggregating agent and an aggregating agent composed of inorganic salts. As the polymer flocculant, one or more of a cationic polymer flocculant, an anionic polymer flocculant, and a nonionic polymer flocculant is appropriately selected in consideration of the surface charge of particles in the crude oil-containing waste liquid. do it. In addition, as the flocculant made of inorganic salts, aluminum sulfate (sulfur clay), polyaluminum chloride, iron chloride, polyiron sulfate, and the like are applicable.

Examples of the cationic polymer flocculant include polyamine-based, polyimine-based, polydiallyldialkylammonium chloride, and polyacrylamide Mannich-modified products. Particularly preferred are polyamine flocculants. The present inventors have confirmed that by using a polyamine-based flocculant as the flocculant, oil-water separation by centrifugation can be performed efficiently and reliably in a short time. As a polyamine type flocculant, a polyamine type condensate is mentioned, for example.
Examples of the anionic polymer flocculant include poly (meth) acrylic acid and salts thereof.
Examples of nonionic polymer flocculants include poly (meth) acrylamide.

Moreover, according to another form of this invention, it is preferable to add an emulsion breaker before performing the said centrifugation process with respect to crude oil containing waste liquid. For example, when the present invention is applied to oil-water separation of warm water washed SLOP, the warm water washed SLOP contains a wax component derived from crude oil and a component having surface activity. Such a waste liquid collects a wax component or a component having surface activity at the interface between water and oil, and forms a state in which water and oil are difficult to directly contact with each other. In this state, an O / W emulsion in which minute oil droplets are stably present in water or a W / O emulsion in which minute water droplets are stably present in oil is obtained.
Since oil droplets in the emulsion (water droplets in the case of W / O type emulsion) are stable and difficult to separate due to a simple specific gravity difference, such waste liquid promotes separation due to specific gravity difference using centrifugation. It is preferable.
By the way, when an emulsion breaker is allowed to act on emulsified oil droplets (or water droplets), oil-water separation can be performed efficiently and reliably in a shorter time. The emulsion breaker is not particularly limited as long as it destroys the emulsion in the crude oil-containing waste liquid, and examples thereof include a cationic emulsion breaker, an anionic emulsion breaker, and a nonionic emulsion breaker. A plurality of these may be added.

  Examples of the anionic emulsion breaker include sulfate ester type and sulfonic acid type anionic emulsion breakers. Examples of sulfuric acid ester type and sulfonic acid type anionic emulsion breakers include polyoxyalkylene alkyl ether sulfates (preferably polyoxyalkylene having an average addition mole number of 1 to 5), alkyl ether sulfate esters (Preferably having 8 to 22 carbon atoms of the alkyl group), dialkyl sulfosuccinate salts, petroleum sulfonate salts and alkyl naphthalene sulfonate salts (preferably alkyl groups having 0 to 5 carbon atoms) and the like. One type or two or more types selected. These salts may be used, for example, ammonium salts, alkali metal (potassium, sodium, etc.) salts, alkaline earth metal (calcium, barium, etc.) salts, tertiary amines (eg monoethanolamine, diethanolamine, triethanolamine). Etc.). Examples of the polyoxyethylene alkyl ether sulfate ester salt include polyoxyethylene lauryl ether sulfate triethanolamine and sodium polyoxyethylene lauryl sulfate.

  Examples of nonionic emulsion breakers include polyoxyalkylene alkyl ethers, alkylphenol alkylene oxide adducts / formalin condensates, polyalkylene glycol copolymers, alkylamine alkylene oxide adducts, and polyether polyol urethane resins. Can be mentioned. Examples of the cationic emulsion breaker include polyamine compounds such as N-polyoxyethylene polyalkylene polyamine, and one or more selected from these can be used.

  Moreover, when adding an emulsion breaker to a waste liquid, it is preferable that the alkylphenol condensate is contained. The present inventors have confirmed that oil-water separation by centrifugation can be performed more effectively by using an alkylphenol condensate as an emulsion breaker. Examples of the alkylphenol condensate include an alkylene oxide adduct of an alkylphenol condensate.

  On the other hand, it is also effective to heat the emulsified waste liquid for oil-water separation. Here, taking a crude oil-containing waste liquid as an example, the wax covers the periphery of the oil droplets (or water droplets) as described above, thereby preventing the oil droplets from coming into direct contact with the surrounding water and stabilizing the emulsion. . By the way, waxes dissolve on the oil side when heated, so when the waste liquid is heated, the waxes dissolve, the oil droplets come into direct contact with the surrounding water, and the interface becomes unstable. Oil-water separation is promoted by making it.

  In addition, suspended substances contained in crude oil-containing waste liquid such as warm water washed SLOP have the role of stabilizing the emulsion by covering the periphery of oil droplets (or water droplets) together with waxes, but floating by heating The wax adhering to the substance is also dissolved and removed in the oil, so that the emulsion becomes unstable. The suspended matter is recovered as sludge in the centrifugal separation process, and the effect of reducing the oil content in the sludge can be expected by removing the wax from the suspended matter by heating.

  Heating also has the role of reducing the viscosity of the crude oil-containing waste liquid. When the viscosity is lowered, an effect of facilitating mixing of the above-described chemicals such as an emulsion breaker and a flocculant can be expected. The emulsion breaker has the effect of entering the surfactant layer on the surface of the oil droplet (or water droplet) and making the surfactant layer easily disturbed. For this reason, when oil droplets collide, it becomes easy to unite, and as a result, an oil droplet becomes coarse and separation is promoted. Since heating has the effect of increasing the dispersion of the emulsion breaker and the surfactant layer itself, the effect of promoting oil-water separation can be expected.

  For the above reasons, it is preferable to heat the waste liquid so that the temperature is 45 ° C. or higher. If the temperature of the waste liquid is less than 45 ° C., the waxes that stabilize the emulsion of the waste liquid may not be dissolved. Therefore, it is difficult to break the emulsion due to dissolution of the waxes, and oil / water separation may be difficult. . In addition, when the temperature of the waste liquid is less than 45 ° C., the viscosity of the waste liquid does not decrease so much, so that the effect of easily mixing chemicals such as an emulsion breaker and a flocculant is difficult to be exhibited, and oil / water separation may also be difficult. There is.

  On the other hand, when the temperature of the crude oil-containing waste liquid rises, the volatilization of the oil component in the crude oil is promoted. For this reason, it is preferable that the temperature of a waste liquid shall be 65 degrees C or less. In particular, when the temperature of the waste liquid exceeds 60 ° C., it also exceeds the flash point of heavy oil, which is generally considered to be difficult to ignite. Furthermore, it is desirable that each facility be sealed so that the combustible gas does not leak easily so that the volatilized oil component does not stay around the facility. Or it is desirable to make it the structure which sucks the gas volatilized from each equipment and volatilizes it in a safe place.

  For the above reasons, the temperature of the waste liquid is preferably in the range of 45 ° C. or higher and 65 ° C. or lower, and more preferably in the range of 45 ° C. or higher and 55 ° C. or lower.

  The crude oil-containing waste liquid treatment facility of the present invention is a waste liquid treatment facility containing crude oil, an addition facility for adding a flocculant to the waste liquid, a heating facility for heating the waste liquid, and the flocculant comprising: And a centrifuge for separating the added and heated waste liquid into oil, water and solids.

Furthermore, another crude oil-containing waste liquid treatment facility according to the present invention is a waste fluid treatment facility containing crude oil, a heating facility for heating the waste liquid, and agglomeration in the waste liquid before and after the heating. An addition facility for adding an agent and an emulsion breaker, and a centrifuge for separating the heated waste liquid to which the emulsion breaker has been added into oil, water and solid matter To do.
In this case, it is preferable that the heating equipment can control the temperature of the waste liquid to a predetermined temperature of 45 ° C. or more and 65 ° C. or less. If the temperature of the waste liquid is less than 45 ° C., the waxes that stabilize the emulsion of the waste liquid may not be dissolved. Therefore, it is difficult to break the emulsion due to dissolution of the waxes, and oil / water separation may be difficult. . In addition, when the temperature of the waste liquid is less than 45 ° C., the viscosity of the waste liquid does not decrease so much, so that the effect of easily mixing chemicals such as an emulsion breaker and a flocculant is difficult to be exhibited, and oil / water separation may also be difficult. There is. On the other hand, the temperature of the waste liquid is preferably set to 65 ° C. or less from the viewpoint of preventing dissipation due to volatilization of oil components in the crude oil as much as possible. In particular, when the temperature of the waste liquid exceeds 60 ° C., it also exceeds the flash point of heavy oil, which is generally considered to be difficult to ignite, so it is more preferable that the temperature of the crude oil-containing waste liquid is 55 ° C. or less.

  Furthermore, in the processing equipment for crude oil-containing waste liquid according to the present invention, an oil / water separation equipment for removing oil contained in the water separated from the centrifuge, and the oil separated by the oil / water separation equipment are stored in the waste liquid. It is preferable to provide a return facility for returning to the tank and processing with the centrifuge again. Here, the oil / water separation equipment for removing the oil contained in the water separated from the centrifugal separator includes a pressure flotation system, a membrane separation system, and an equipment for separating oil by API or CPI using a specific gravity difference. .

<Description of Embodiment>
(Embodiment 1)
The treatment facility of Embodiment 1 is a facility for treating a crude oil-containing waste liquid, for example, a warm water washing SLOP that is a washing waste liquid of a crude oil storage tank. As shown in FIG. 1, a flocculant and an emulsion breaker are added to the crude oil-containing waste liquid. A mixing tank 1 for adding, a heat exchanger 2 for heating the waste liquid flowing out from the mixing tank, and a centrifuge 3 for centrifuging the heated waste liquid flowing out from the heat exchanger 2 I have. The mixing tank 1 is connected to a flocculant storage tank (not shown) via a chemical injection pump 4 and is connected to an emulsion breaker storage tank (not shown) via a chemical injection pump 5. The heat exchanger 2 is connected to a steam generating boiler (not shown) via a steam pipe 6. Furthermore, a circulation pipe 7 for feeding back the heated waste liquid flowing out from the heat exchanger 2 to the mixing tank 1 is provided, and a circulation pump 8 is provided in the middle of the circulation pipe 7.

In the treatment facility of the first embodiment configured as described above, first, crude oil-containing waste liquid is supplied to the mixing tank 1, and the flocculant and the emulsion breaker are added by the chemical injection pumps 4 and 5. Stir and mix. The waste liquid flowing out from the mixing tank 1 enters the heat exchanger 2, is heated by the steam supplied from the steam pipe 6, and is sent to the centrifuge 3. Furthermore, it is centrifuged by the centrifuge 3, and is separated and discharged into a light liquid mainly composed of oil, a heavy liquid mainly composed of water, and sludge. The heat source supplied to the heat exchanger 2 can also use hot water. Furthermore, since the condensed water of the steam supplied from the steam pipe 6 to the heat exchanger 2 becomes hot hot water, it can be used as an auxiliary heat source for raising the temperature of the crude oil-containing waste liquid.
As described above, in the treatment facility of the first embodiment, before the crude oil-containing waste liquid is separated into light liquid, heavy liquid, and sludge by the centrifuge 3, the flocculant and the emulsion breaker are added and mixed in the mixing tank 1. The For this reason, oil, water, and solids of the crude oil-containing waste liquid can be efficiently separated and recovered in a short time. Furthermore, since the waste water is fed back from the heat exchanger 2 to the mixing tank 1 using the circulation pipe 7 and the circulation pump 8, the crude oil-containing waste liquid can be uniformly heated. For this reason, waxes that stabilize the emulsion of the waste liquid dissolve, the emulsion breaks, and oil-water separation becomes easy

(Embodiment 2)
As shown in FIG. 2, in the treatment facility of Embodiment 2, the heat exchanger 12 is provided on the upstream side of the mixing tank 11. Other configurations are the same as those of the processing facility according to the first embodiment shown in FIG. 1, and the same components are denoted by the same reference numerals and detailed description thereof is omitted.

  In the treatment facility of the second embodiment, since the waste liquid is heated by the heat exchanger 12 before adding and mixing the flocculant and the emulsion breaker, the oil content in the waste liquid is added before the flocculant and the emulsion breaker are added. The viscosity is lowered, and there is an advantage that the medicine can be mixed and dispersed in the mixing tank 11 more smoothly and in a short time. Other operations and effects are the same as those of the processing facility of the first embodiment.

(Embodiment 3)
In the processing facility of Embodiment 3 shown in FIG. 3, a recovery oil tank 21 for recovering a light liquid discharged from the centrifuge 3 and an oil component in a heavy liquid discharged from the centrifuge 3 are separated. An oil / water separation tank 22 and a recovered oil return pipe 23 for returning the oil separated in the oil / water separation tank 22 to the mixing tank 1 and the circulation pipe 7 are provided. Other configurations are the same as those of the processing facility according to the first embodiment shown in FIG. 1, and the same components are denoted by the same reference numerals and detailed description thereof is omitted.

In the treatment facility of the third embodiment, the light liquid is composed of oil remaining after the moisture and sludge are separated, but the discharged light liquid is returned to the oil refining process again as recovered oil through the recovered oil tank 21. Will be. In addition, although the main component of the heavy liquid is water, some oil and sludge that could not be separated may remain, so after being discharged from the centrifuge 3, once supplied to the oil-water separation tank 22, After removing oil and sludge, it is discharged as treated water. Here, in order to separate and remove oil and sludge from the water in the oil / water separation tank 22, it is possible to apply API or CPI which is a separation device using a specific gravity difference. A membrane filtration device using a microfiltration membrane or a pressure levitation device may be installed instead of the oil / water separation tank 22. Further, in order to further recover the oil from the concentrated oil or sludge, it is preferable to return it to the crude oil-containing waste liquid through the recovered oil return pipe 23. This is because when oil remains in the water tank after oil-water separation, the suction of the circulation pump 8 installed at the inlet of the preceding mixing tank 1 or the circulation pipe 7 that feeds back the heat from the heat exchanger 2 to the mixing tank 1 In order to return to the side and improve the oil recovery rate, it is returned as necessary. Further, since the water separated in the oil / water separation tank 22 contains agglomerated flocs, it is possible to enhance the agglomeration effect by returning it to the crude oil-containing waste liquid.
Other operations and effects are the same as those of the processing facility of the first embodiment.

(Embodiment 4)
As shown in FIG. 4, the treatment facility of the fourth embodiment is configured to circulate crude oil-containing waste liquid such as hot water washing SLOP between the mixing tank 31 and the heat exchanger 32. The crude oil-containing wastewater discharged from the mixing tank 31 is configured to be sent to a centrifuge 33 after an emulsion breaker and a flocculant are supplied from a medicine supply tank (not shown). The centrifuge 33 separates the crude oil-containing wastewater into a light liquid containing a large amount of crude oil, a heavy liquid containing a lot of water, and sludge. The light liquid is stored in a light liquid tank 34 and the heavy liquid is stored in a heavy liquid tank 35. It has become so. The mixing tank 31, the light liquid tank 33 and the heavy liquid tank 34 have a sealed structure, and a pipe 36 for removing the generated gas is connected, and the other end of the pipe 36 is connected to the odorant 37. Yes.

  In the treatment facility of Embodiment 4 configured as described above, since the crude oil-containing wastewater is heated by the heat exchanger 32 before being sent to the centrifuge 33, before the flocculant and the emulsion breaker are added, The viscosity of the oil in the waste liquid is lowered, the mixing of the flocculant and the emulsion breaker is facilitated, and the oil-water separation of the emulsion is promoted. The heating is preferably limited to about 60 ° C. in order to suppress the volatilization of components in the crude oil. In addition, it is also possible to install mixing equipment such as a line mixer and a stirring tank after adding the flocculant and the emulsion breaker. Further, in order to maintain the temperature up to the centrifuge, it is preferable that the heated pipe and the centrifuge have a heat insulating structure.

  In the fourth embodiment, in order to remove volatile components from the hot water cleaning SLOP, the mixing tank 31, the light liquid tank 34, the heavy liquid tank 35, and the like have a sealed structure, and the piping 36 for removing the generated gas is provided. Therefore, volatile components can be safely diffused into the atmosphere. Note that, depending on the concentration of the volatile component, the volatile component may exceed the explosion lower limit value. Therefore, it is desirable to provide a backfire prevention device in the odor stack or the piping as necessary.

(Embodiment 5)
In Embodiment 5 shown in FIG. 5, except that the medicine supply tank for the emulsion breaker is not installed, and the piping 36 and the odor stack 37 for eliminating the generated gas are not installed, Since it is the same as that of the processing equipment, the same components are denoted by the same reference numerals and detailed description thereof is omitted.
According to the treatment facility of the fifth embodiment, the waste liquid is heated while being circulated between the mixing tank 31 and the heat exchanger 32, and then the flocculant is added. That is, since the flocculant is added to the waste liquid that has been heated to lower the viscosity of the oil, there is an advantage that mixing and dispersion with the flocculant can be performed more smoothly and in a short time. Other operations and effects are the same as those of the processing facility of the first embodiment. In the fifth embodiment, only the flocculant is added and the centrifugal separation is performed without adding the emulsion breaker, but depending on the properties of the crude oil-containing waste liquid to be treated, the effect of separating the oil and water only by adding the flocculant. May be obtained. For this reason, it is desirable to conduct a laboratory-scale treatment test in advance to determine the appropriate chemical selection and injection rate.

The flocculant used in the treatment facilities of Embodiments 1 to 5 above refers to an additive added to agglomerate particles in the crude oil-containing waste liquid. For example, a flocculant composed of a polymer flocculant or inorganic salts is used. Can be mentioned. As the polymer flocculant, one or more of a cationic polymer flocculant, an anionic polymer flocculant, and a nonionic polymer flocculant is appropriately selected in consideration of the surface charge of particles in the crude oil-containing waste liquid. do it. As the flocculant, for example, a polyamine type flocculant such as Hakutron B-733 manufactured by Hakuto is suitable.
In addition, the emulsion breaker used in the treatment facilities of Embodiments 1 to 5 above is an agent that facilitates separation of an emulsion liquid into an aqueous phase and an oil phase, and is a nonionic alkylphenol such as Hakutoru E-523 manufactured by Hakuto. Condensates, nonionic polyether polyol urethane resins such as EW-01 manufactured by Hakuto, and those containing an anionic dialkylsulfosuccinate salt such as EW-02 manufactured by Hakuto are suitable.
The injection amount of each of these chemicals may be determined in advance by conducting an oil-water separation test on a small scale and determining the optimum addition amount as appropriate.
In addition, when the waste liquid in which the flocculant and the emulsion breaker are added and mixed in the mixing tank 1 in the first embodiment is heated in the heat exchanger 2, or in the second embodiment, the waste liquid heated in the heat exchanger 12 is used. When a flocculant and an emulsion breaker are added and mixed in the mixing tank 11, the viscosity of the oil in the waste water is lowered, and thus the centrifugal separation is appropriately performed. According to the test results of the inventors, it is desirable to heat to 40 ° C. or higher in order to properly treat oil-water separation. However, depending on the components in the oil contained, oil components having a low boiling point may be present, and if the temperature is too high, the amount of evaporation of such volatile components increases, so that appropriate temperature control is important. In addition, since the low boiling point components may evaporate and vaporize and diffuse into the atmosphere, which may cause odors, the mixing tank 1, the subsequent centrifugal separator 3 and the oil / water separation tank 22 are generated as a sealed structure. It is desirable that the gas is separately sucked into the processing facility or led to the odor and diffused. In addition, since light liquid and recovered oil may be ignited by static electricity, it is desirable to ground the centrifuge, the pipe through which the light liquid and recovered oil flow. Further, it is also preferable to keep the tank or centrifuge to be sealed, replace with nitrogen gas, and maintain an environment in which ignition is difficult.

The heated crude oil-containing waste liquid is supplied to the centrifuge 3. The centrifuge used in the present invention is desirably a three-phase separation type centrifuge. In general, a crude oil-containing waste liquid such as warm water washed SLOP often contains solid sludge in addition to oil and water. In a three-phase separation type centrifuge, oil, water and sludge can be separated in one step.
In the case of crude oil-containing waste liquid, it is desirable to determine the supply amount of oil-containing waste water to the centrifuge while confirming the distribution of light and heavy liquid water discharged from the centrifuge.

The Example of the processing method of the crude oil containing waste liquid of this invention is explained in full detail, comparing with a comparative example.
Example 1
In Example 1, in order to examine oil-water separation of the hot water washing SLOP using a three-phase centrifuge, evaluation at a laboratory level was performed.
The warm water washed SLOP (water content 18.8 mass%) discharged from the crude oil storage tank was used as a test waste liquid. The waste liquid for test was heated to 50 ° C. in a water bath, and then an emulsion breaker (Hakutol E-523) containing an alkylphenol condensate was added at a rate of 10 mg / kg per crude oil to be treated and stirred well. Next, after adding a polyamine type flocculant (Haktron B-733) at a rate of 500 mg / kg, the mixture was further stirred. The liquid mixture thus obtained was supplied to a centrifuge and centrifuged to separate into three phases of light liquid, heavy liquid and sludge. The volume ratio of each phase was 15: 23: 2. The light liquid was a brown liquid with viscosity, and the water content was measured to be 0.8% by mass. The light liquid was considered to be almost oil. The heavy liquid was a slightly brownish transparent liquid. The heavy liquid COD, the amount of hexane extract, total nitrogen, total phosphorus, and various heavy metal concentrations were measured. As a result, as shown in Table 1, the normal hexane extract concentration was 1.4 mg / L, and the heavy liquid was considered to consist essentially of water. As for other components, although the iron concentration was slightly high, the concentrations of nitrogen, phosphorus and heavy metals were low, and the result was good water quality.

(Example 2)
In Example 2, the hot water washed SLOP (water content = 82%) discharged from the crude oil storage tank was used for the test. Hactron B-733 as a flocculant was added to the test oil so as to be 500 mg / kg and stirred, and an emulsion breaker was not added. About the others, it processed by the method similar to Example 1. FIG.

(Example 3)
In Example 3, Hactol E-523 was added to the test oil as an emulsion breaker to the same hot water washed SLOP as in Example 2 and stirred, and then Haktron B-733 was added as a flocculant to 500 mg / kg. It added to the test oil so that it might become, and it stirred. About the other, the process similar to Example 1 was performed.

(Comparative Example 1)
In Comparative Example 1, neither a flocculant nor an emulsion breaker was added to the same hot water washing SLOP as in Example 2. About the other, the process similar to Example 1 was performed.

(Comparative Example 2)
In Comparative Example 2, without adding a flocculant to the same hot water washed SLOP as in Example 2, Hactol E-523 was added to the test oil as an emulsion breaker so as to be 10 mg / kg and stirred. About the other, the process similar to Example 1 was performed.

<Result>
The result of the processing is shown in FIG. In Comparative Example 1 in which neither an emulsion breaker nor a flocculant was added, oil and water were not separated even after centrifugation. The same result was obtained in Comparative Example 2 in which only the emulsion breaker was added.
In contrast, in Example 2 in which only the flocculant was added and stirred, and in Example 3 in which both the emulsion breaker and the flocculant were added and stirred, the oil, water, and sludge were separated into three phases. From the above, it has been clarified that the addition of a flocculant is essential in order to separate the water, oil, and sludge of the hot water washed SLOP.

Example 4
In Example 4, the treatment shown in FIG. 4 was used to treat the hot water washing SLOP generated from the washing of the crude oil tank. The water content of the hot water washed SLOP subjected to the test was 26 to 35%, and the toluene insoluble content was about 1%.
In the treatment test, warm water washed SLOP serving as raw water was heated to a predetermined temperature. Subsequently, Hakutol E-523 as an emulsion breaker and Haktron B-733 as a flocculant were added, and then supplied to a three-phase separation type centrifuge.
The water content of the recovered oil (light liquid) when hot water washed SLOP is supplied to the centrifuge at 400 L / hr and the E-523 addition rate is added at a rate of 0 to 40 mg / L is shown in FIG. In addition, the liquid temperature of warm water washing | cleaning SLOP was set to 52 degreeC, and B-733 addition rate was set to 300 mg / L.
As a result, as shown in FIG. 7, the water content of the recovered oil tends to decrease as the E-523 addition rate increases, and the water content decreases to about 1.1% under the condition of the addition rate of 40 mg / L. did. From this result, it was shown that increasing the addition rate of the emulsion breaker while adding the flocculant is effective in reducing the water content of the recovered oil. In general, an emulsion breaker is a kind of surfactant, and it is known that emulsification is promoted again when the addition rate is excessive. Therefore, in this example, the maximum emulsion breaker addition rate was set to 40 mg / L. .

(Example 5)
In Example 5, in order to evaluate the effect of the addition of the flocculant, after warming the warm water washed SLOP, E-523 was added at a rate of 20 mg / L and B-733 at a rate of 500 mg / L, and a three-phase separation type was added. The test supplied to the centrifuge was performed.
As a result, the suspended solid concentration of the obtained heavy liquid was 1000 mg / L, and the COD was 670 mg / L.

(Comparative Example 3)
In Comparative Example 3, the same warm water washed SLOP as in Example 5 was heated, and then 20 mg / L of E-523 was added, and a test was performed in which it was supplied to a three-phase separation type centrifuge.
As a result, the obtained separated water (heavy liquid) contains a black floating substance, and as in Comparative Example 2, the floating substance in the heavy liquid remains as it is without being precipitated. It was a black suspension. From this result, in order to improve the water quality of the heavy liquid, it was considered effective to add an aggregating agent to facilitate aggregation of suspended solids as in the case of Example 2 and Example 3. The recovered heavy liquid had a suspended solid concentration of 3400 mg / L and a chemical oxygen demand (COD) of 1800 mg / L.
From the comparison between Example 5 and Comparative Example 3, it was confirmed that the flocculant was effective in improving heavy liquid properties by adding the flocculant before the centrifugal separation.

(Example 6)
In Example 6, the relationship between the temperature of the hot water washed SLOP and the oil moisture content was investigated. Here, the supply amount of the hot water washing SLOP to the centrifuge was set to 250 L / hr and 500 L / hr. The results are shown in FIG. Here, the temperature of the hot water washing SLOP was adjusted so that the temperature of the recovered oil (light liquid) discharged from the centrifuge became a set value.
As a general trend, the water content of the recovered oil tends to decrease as the temperature increases, and the water content tends to decrease if the hot water wash SLOP supply to the centrifuge is low at the same temperature. Was recognized.
Under the condition of 250 L / hr, the water content decreased to less than 2% at 50 ° C. or higher, and the water content decreased to 0.9% at 55 ° C. In addition, when the supply amount of hot water washing SLOP was 500 L / hr, the water content decreased to less than 2% when it exceeded 55 ° C, and the water content decreased to 1.4% at 66 ° C. In this case, the light liquid needs to be collected in a container that can be sealed.

(Example 7)
In Example 7, the hot water washing SLOP was processed by the same processing equipment as in Example 4. The warm water washed SLOP was heated to 50 ° C. Next, 200 mg / L of EW-01 and 20 mg / L of EW-02 (both Hakuto Co., Ltd.) were respectively added as emulsion breakers, and 300 mg / L of Hactron B-733 was added as a flocculant, and then three-phase It supplied to the separation type centrifuge.
The supply amount to the centrifuge was set to 400 L / hr, and recovered oil (light liquid), separated water (heavy liquid), and sludge were recovered. The water content of the recovered oil was 0.6%, which was slightly lower than the water content of the recovered oil obtained in each test of Example 4.

  The present invention is not limited to the description of the embodiments and examples of the invention described above. Various modifications are also included in the present invention as long as those skilled in the art can easily conceive without departing from the scope of the claims.

  The present invention can be used for the treatment of waste liquid containing crude oil.

Claims (11)

A method for treating a waste liquid containing crude oil,
An addition step of adding a flocculant to the waste liquid;
A heating step of heating the waste liquid before the addition of the flocculant, at the time of addition, and at least any time after the addition;
A centrifugal separation step of separating the waste liquid to which the flocculant has been added into three components of oil, water and solids,
A method for treating a crude oil-containing waste liquid, wherein at least a part of the water separated by the centrifugation step is returned to the waste liquid.   2. An oil-water separation step of separating the water separated in the centrifugal separation step is provided, and the separated water obtained in the oil-water separation step is returned to the waste solution. Processing method.   The method for treating a crude oil-containing waste liquid according to claim 1 or 2, wherein a step of adding an emulsion breaker is performed before the centrifugal separation step. A method for treating a waste liquid containing crude oil,
An addition step of adding a flocculant and an emulsion breaker to the waste liquid;
Mixing the waste liquid to which the flocculant and the emulsion breaker have been added in a mixing tank (1);
A heating step of heating the waste liquid mixed in the mixing step by a heating facility (2);
A part of the waste liquid heated in the warming step is returned to the mixing tank (1) through a pipe connection, and is circulated between the mixing tank (1) and the heating equipment (2) so as to circulate the waste liquid. A circulation step in which the temperature of the waste liquid is made uniform and the emulsion breakage of the waste liquid occurs to facilitate oil-water separation;
Centrifugation in which the flocculant and the emulsion breaker are added and mixed, and the heated waste liquid is centrifuged to separate a light liquid mainly composed of oil, a heavy liquid mainly composed of water, and sludge. Process,
A light liquid tank supplying step of supplying a light liquid mainly composed of the oil to the light liquid tank (34);
A heavy liquid tank supplying step of supplying the heavy liquid mainly composed of water to the heavy liquid tank (35);
The mixing tank (1), the light liquid tank (34) and the heavy liquid tank (35) have a sealed structure, pipes are connected to the tanks, and pipes for removing volatile gases generated in the tanks. A gas removal step of diffusing volatile components into the atmosphere by a odor stack (37) connected to
A method for treating crude oil-containing waste liquid, comprising: A method for treating a waste liquid containing crude oil,
A heating step of heating the waste liquid by a heating facility (12);
An addition step of adding a flocculant and an emulsion breaker to the heated wastewater;
Mixing the waste liquid to which the flocculant and the emulsion breaker have been added in a mixing tank (1);
A part of the waste liquid mixed in the mixing step is returned to the heating equipment (12) by pipe connection, and is circulated between the heating equipment (12) and the mixing tank (11) to thereby remove the waste liquid. A circulation step in which the temperature is made uniform, and the emulsion of the waste liquid breaks down to facilitate oil-water separation;
Centrifugation step of separating the waste liquid mixed in the mixing step into a light liquid mainly composed of oil, a heavy liquid mainly composed of water, and sludge,
A light liquid tank supplying step of supplying a light liquid mainly composed of the oil to the light liquid tank (34);
A heavy liquid tank supplying step of supplying the heavy liquid mainly composed of water and the heavy liquid tank (35);
The mixing tank (1), the light liquid tank (34) and the heavy liquid tank (35) have a sealed structure, pipes are connected to the tanks, and pipes for removing volatile gases generated in the tanks. A gas removal step of diffusing volatile components into the atmosphere by a odor stack (37) connected to
A method for treating crude oil-containing waste liquid, comprising:   The method for treating a crude oil-containing waste liquid according to any one of claims 3 to 5, wherein the emulsion breaker contains an alkylphenol condensate.   The crude oil-containing waste liquid treatment method according to any one of claims 1 to 6, wherein the crude liquid-containing waste liquid is heated at a temperature in the range of 45 ° C to 65 ° C before the centrifugation step. .   The method for treating a crude oil-containing waste liquid according to any one of claims 1 to 7, wherein the flocculant contains a polyamine flocculant. A waste liquid treatment facility containing crude oil,
A mixing tank (1) to which the waste liquid is supplied;
An addition facility (4, 5) for adding the flocculant and the emulsion breaker to the waste liquid in the mixing tank;
A heating facility (2) for heating the waste liquid from the mixing tank to 45 ° C. to 65 ° C .;
A pipe (7) for circulating the waste liquid heated by the heating equipment (2) between the mixing tank (1) and the heating equipment (2) to uniformly heat the waste liquid. And the pump (8),
Centrifuges (3), (33) for separating the waste liquid from the heating facility into a light liquid mainly composed of oil, a heavy liquid mainly composed of water, and sludge;
A light liquid tank (34) for storing a light liquid mainly composed of the oil;
A heavy liquid tank (35) for storing the heavy liquid containing water as a main component, and the mixing tank, the light liquid tank, and the heavy liquid tank have a sealed structure, and each tank has a sealed structure. A crude oil-containing waste liquid treatment facility, characterized in that a plumbing (37) connected to a pipe and connected to a pipe for removing volatile gas generated in each tank is provided. A waste liquid treatment facility containing crude oil,
A heating facility (12) for heating the waste liquid to 45 ° C. to 65 ° C .;
A mixing tank (11) for storing and mixing the heated waste liquid;
An addition facility (4, 5) for adding the flocculant and the emulsion breaker to the mixing tank (11);
A waste liquid from the mixing tank (11) is circulated between the mixing tank (11) and the heating equipment (12), and a pipe (7) and a pump (8) for uniformly heating the waste liquid. )When,
A centrifuge (3) for separating the waste liquid from the mixing tank (11) into a light liquid mainly composed of oil, a heavy liquid mainly composed of water, and sludge;
A light liquid tank (34) for storing a light liquid mainly composed of the oil;
A heavy liquid tank (35) for storing the heavy liquid containing water as a main component, and the mixing tank, the light liquid tank, and the heavy liquid tank have a sealed structure, and a pipe is provided in each tank. A crude oil-containing waste liquid treatment facility, characterized in that it is connected to a pipe (37) connected to a pipe for removing volatile gas generated in each tank. A waste liquid treatment facility containing crude oil,
A mixing tank (1) to which the waste liquid is supplied;
An addition facility for adding a flocculant and an emulsion breaker to the waste liquid in the mixing tank;
A heating facility (2) for heating the waste liquid to 45 ° C. to 65 ° C .;
A centrifuge for adding the flocculant and the emulsion breaker and separating the heated waste liquid into a light liquid mainly composed of oil, a heavy liquid mainly composed of water, and sludge;
A light liquid tank (34) for storing a light liquid mainly composed of the oil;
A heavy liquid tank (35) for storing the heavy liquid containing water as a main component, and the mixing tank, the light liquid tank, and the heavy liquid tank have a sealed structure, and each tank has a sealed structure. A pipe is connected, and a odor stack (37) connected to the pipe for removing volatile gas generated in each tank is provided,
A pipe (7) and a pump for circulating the waste liquid heated by the heating equipment (2) or the waste liquid from the mixing tank to the mixing tank and the heating equipment and uniformly heating the waste liquid (8) and
An oil / water separation tank (22) for separating oil in the heavy liquid discharged from the centrifuge;
A recovered oil return pipe (23) for returning the separated oil from the oil / water separation tank (22) to the waste liquid, the mixing tank, the pipe and a pump;
A crude oil-containing waste liquid treatment facility characterized by comprising: