JP5767593B2 - Oil content water treatment system - Google Patents

Description

  The present invention relates to a technique for treating oil-containing water separated from an object to be treated, and, for example, treats industrial wastewater and water accompanying oil / natural gas production (hereinafter referred to as “associated water”). Regarding technology.

  When producing oil and natural gas, a large amount of accompanying water is also produced. Since the accompanying water is unnecessary as a product of oil or natural gas, it must be disposed of separately from oil or natural gas.

  A technique disclosed in Non-Patent Document 1 is known as a process technique for accompanying water. A product containing oil, natural gas, and associated water is first guided to a three-phase separator, and is divided into a gas that is a gas above, and an oil that is a liquid below and associated water based on the specific gravity difference. Furthermore, because of the sill installed in the space where the liquid in the three-phase separator is located, only relatively light oil can exceed the sill as the liquid, so gas, oil, The accompanying water can be taken out. In addition, when hardly containing a volatile component (gas), the two-phase separator of oil and accompanying water can be used.

  Since the accompanying water that has come out of the three-phase separator maintains a high pressure, it is guided to the hydrocyclone at high speed. In the hydrocyclone, the oil is separated into the inside and the water is separated into the outside by centrifugal force, and the oil can be extracted from the inside. The oil is combined with the oil taken out from the three-phase separator and sent to the oil refining line.

  On the other hand, the accompanying water from which the oil component has been removed by the hydrocyclone still contains about 50 to 100 mg / L of the oil component (emulsion oil) that has been emulsified (suspended), and thus cannot be directly released into nature. Therefore, removal of emulsion oil is attempted by using techniques such as IGF (Induced Gas Floatation). IGF injects gas and flocculant into the accompanying water to agglomerate the oil and gas to form an agglomerate with a low specific gravity (hereinafter referred to as “floc”). It removes oil.

  However, in order to uniformly disperse the gas in the accompanying water and create a floc having a uniform specific gravity, it is necessary to make the gas fine and insert it, which requires a great deal of energy. On the other hand, if an attempt is made to make a floc having a low specific gravity by suppressing the input energy of the gas, it is necessary to make the agglomeration time and the amount of injected gas excessive, resulting in an increase in size of the apparatus. In particular, in the case of offshore facilities rather than onshore, downsizing of the apparatus is an important issue. Moreover, when heavy oil is a removal target, there is a problem that a sufficient specific gravity difference cannot be obtained between water and floc, and good separation performance cannot be obtained.

  With respect to these problems, for example, Patent Document 1 discloses a technique for removing emulsion oil by an aggregation magnetic separation method. The agglomeration magnetic separation method means that flocculant and magnetic powder are put into the oil-containing water to be treated, and agglomerated flocs are produced by stirring, and the flocs are recovered by magnetic force. In this method, the emulsion oil is removed from the water to obtain treated water. Since this method uses magnetic force for separation, it is possible to stably and accurately remove emulsion oil without being affected by the difference in specific gravity between water and emulsion oil. Moreover, since the magnetic powder is injected, it is easy to disperse in the oil-containing water, and it is easy to make a floc having uniform magnetization characteristics.

JP 2009-656 A

"Process Systems-VORTOIL Deoiling Hydrocyclones", [online], CAMERON, [searched on December 13, 2011], Internet <URL: http://www.cam.com/Forms/Product.aspx?prodID=30c75393 -87cc-431a-a28d-848dffc80c1b>

  However, in the aggregation magnetic separation method, when the recovered floc is discarded as industrial waste, the magnetic powder contained in the floc is also discarded. Therefore, the magnetic powder must be periodically supplied to the entire system, which increases the cost. Moreover, since the magnetic powder is contained in the collected floc, the cost for disposal of industrial waste is increased accordingly.

  Therefore, the present invention has been made in view of the circumstances described above, and in the oil-containing water treatment of the aggregation magnetic separation method, at least a part of the magnetic powder contained in the recovered floc is reused without being discarded. The challenge is to achieve cost reduction.

In order to solve the above problems, the oil-containing water treatment system of the present invention is an oil-water separation that separates an object to be treated containing oil and water into oil and oil-containing water that is water in which the oil is suspended. Adding a separator, a solid-liquid separation unit for separating and removing solids from the separated oil-containing water, and a flocculant and magnetic powder to the oil-containing water from which the solids have been removed. Agglomerated part for generating a floc comprising the aggregate of suspended oil and the magnetic powder adhering thereto, a magnetic separation part for separating the generated flock from the oil-containing water by magnetic force, and A magnetic powder recovery unit that recovers magnetic powder by magnetic force from the separated floc, and a residue of the floc after the magnetic powder is recovered in the magnetic powder recovery unit is returned to the upstream side of the solid-liquid separation unit. In the magnetic powder recovery unit It characterized by having a a return mechanism for returning to the agglomeration section and the recovered magnetic powder have.
Other means will be described later.

  According to the present invention, it is possible to realize cost reduction by reusing at least a part of the magnetic powder contained in the recovered floc in the aggregated magnetic separation type oil-containing water treatment without discarding.

It is the schematic of the structure of 1st Embodiment of this invention. It is the schematic of the structure of 2nd Embodiment of this invention. It is the schematic of the structure of 3rd Embodiment of this invention.

  Hereinafter, first to third embodiments will be described with reference to the drawings as modes for carrying out the present invention (hereinafter referred to as “embodiments”).

(First embodiment)
As shown in FIG. 1, in the oil-containing water treatment system 100a (100), the liquid 1 to be treated containing crude oil or the like first flows into a three-phase separator 2 (oil-water separator, solid-liquid separator). The three-phase separator 2 separates a liquid to be treated 1 (a material to be treated) containing gas, oil (crude oil), and water into gas, oil, and oil-containing water that is water in which the oil is suspended. It has a function.

  When the liquid 1 to be treated flows into the three-phase separator 2, it is separated into gas (gas) and liquid due to the difference in specific gravity, and oil and water in the liquid (accompanying water. Oil content is contained) by the sill 3 installed in the space where the liquid is located. Water). The gas is discharged from the gas outlet 4, the oil is discharged from the oil outlet 5, and the accompanying water is discharged from the water outlet 6.

  At this time, the purity of the oil discharged from the oil take-out port 5 is almost 100%. However, as described above, the accompanying water discharged from the water take-out port 6 contains 50 parts of the emulsified (suspended) oil. About 100 mg / L is included. Further, when the three-phase separation is performed, a drain valve 7 (solid-liquid separation unit) is provided at the lower part of the three-phase separator 2 so that the three-phase separator 2 is precipitated at the bottom on the left side in FIG. The unnecessary solid matter can be removed from the solid matter outlet 8 (solid-liquid separation unit). That is, in the first embodiment, the three-phase separator 2 also serves as a solid-liquid separation unit that separates and removes unnecessary solids from the accompanying water.

  The accompanying water taken out from the water outlet 6 is sent to the rapid stirring tank 9 (aggregation part). At that time, since unnecessary solid matter in the three-phase separator 2 is removed from the solid matter outlet 8, the load on the apparatus after the rapid stirring tank 9 can be reduced. In the rapid agitation tank 9, an inorganic flocculant such as PAC (polyaluminum chloride), ferric sulfate, ferric chloride, aluminum sulfate or the like is added from the inorganic flocculant tank 11 through the inorganic flocculant injection pump 14. Further, magnetic powder, for example, iron tetroxide powder, is added from the magnetic powder tank 12 through the magnetic powder injection pump 15 to generate a floc composed of aggregates of suspended oil and magnetic powder adhering thereto. The

  As a result, the oil particles to be removed, or the oil particles and the magnetic powder aggregate to form a small flock (micro flock). Next, a polymer flocculant, such as an anionic or nonionic polyacrylamide, is added from the polymer flocculant tank 13 through the polymer flocculant injection pump 16 in the subsequent slow stirring tank 10 (aggregation part). By stirring at a low speed, micro flocs are crosslinked with a polymer flocculant to form large flocs.

  The water (flocculated water) containing a large number of flocs formed in this way flows into the magnetic separation unit 17. The magnetic separation unit 17 includes a magnetic drum 18 containing a permanent magnet such as a neodymium magnet, and a scraper 19 that is in contact with the outer periphery of the magnetic drum 18 or installed in the vicinity of the magnetic drum 18. The substantially lower half of the magnetic drum 18 is immersed in the condensed water, and the substantially upper half faces the upper space.

  When the condensed water comes into contact with or passes through the magnetic drum 18, the magnetic powder contained in the floc is adsorbed on the outer peripheral surface of the magnetic drum 18 by the magnetic force of the permanent magnet. The adsorbed floc moves along with the rotation of the magnetic drum 18 and is scraped off by the scraper 19 (separated from the condensed water).

  If a gap of about 1 mm, for example, is provided between the scraper 19 and the surface of the magnetic drum 18, the gap portion of the floc adsorbed on the surface of the magnetic drum 18 is not scraped off. Since it does not fall while adsorbed, the quality of treated water is not adversely affected. Further, if the gap is provided in this way, the scraper 19 does not directly touch the surface of the magnetic drum 18, so that the wear on the surface of the magnetic drum 18 can be greatly reduced. The condensed water from which the floc has been removed is discharged as treated water 21, and the removed floc is stored in the floc water tank 20 as slurry-like floc water together with the contained water.

  Flock water is sent from the flock water tank 20 to the two-fluid nozzle 25 by the flock water transfer pump 22. At the same time, high-pressure gas, for example, air having a gauge pressure of 0.03 to 0.5 MPa (megapascal), nitrogen, natural gas, or the like is fed into the two-fluid nozzle 25 from the high-pressure gas pipe 23 via the high-pressure gas flow rate adjustment valve 24. It is. Thereby, in the two-fluid nozzle 25, a shear force is generated between the flock water and the high-pressure gas, and the flock is decomposed by this force.

  From the flocs thus disassembled, magnetic powder, strictly speaking, a magnetic powder with a large proportion of magnetic powder (referred to as “recovered magnetic powder”) is recovered by magnetic force by a small magnetic separator 26 (magnetic powder recovery unit). Then, the magnetic powder is reused by returning the recovered magnetic powder to the magnetic powder tank 12 by the recovered magnetic powder return line 27 (return mechanism). Further, the remaining residue, which is the remaining flocked water from which the recovered magnetic powder has been removed, is pressurized by the pump 29 (return mechanism) via the residue return line 28 (return mechanism) and returned to the upstream line of the three-phase separator 2. To do. At this time, the residue contains unnecessary solids, agglomerated oil, magnetic powder that could not be removed, water, etc., but unnecessary solids and magnetic powder that could not be recovered were removed from the solid matter outlet. 8 can be taken out as sludge, and the agglomerated oil can be taken out from the oil outlet 5 and the water can be taken out from the water outlet 6.

  Here, the magnetic drum is used in both the magnetic separation unit 17 and the small magnetic separator 26. However, in the magnetic separation unit 17, the flow direction of water and the rotation direction of the magnetic drum are the same so as not to break the flock. Therefore, it is preferable to make the relative speed as small as possible and to break the floc in the small magnetic separator 26, so that the relative speed is increased by reversing the water flow direction and the rotation direction of the magnetic drum.

  As described above, according to the oil-containing water treatment system 100 of the first embodiment, by performing the oil-containing water treatment of the cohesive magnetic separation method, it is possible to realize a stable treatment regardless of the specific gravity difference between emulsion oil and water. Further, at least a part of the magnetic powder contained in the recovered floc can be reused without being discarded, thereby realizing cost reduction.

  In other words, not all of the magnetic powder flows from the magnetic separator 26 to the recovered magnetic powder return line 27, and a part (for example, about 10%) returns to the upstream line of the three-phase separator 2 as a residue. However, at least a part of the magnetic powder contained in the recovered floc (for example, about 90%) can be reused via the recovered magnetic powder return line 27 without being discarded, thereby significantly reducing the cost. Can be realized.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected about the same structure as 1st Embodiment, and duplication description is abbreviate | omitted suitably. In the oil-containing water treatment system 100b (100) of the second embodiment shown in FIG. 2, the difference from the case of the first embodiment shown in FIG. 1 is that the solid-liquid separation separator 30 ( (Solid-liquid separation unit) (for example, cyclone type), line 31 and oil / water separation separator 33 (for example, cyclone type) are provided, and the residue from the magnetic separator 26 is returned upstream of the solid-liquid separation separator 30. Is a point.

  The residue contains an aggregating agent and often still has an aggregating effect. Therefore, a slight agglomeration reaction occurs in the solid-liquid separation separator 30 due to the influence of the returned residue, and the solid matter is easily separated. Similarly, the separation performance is improved by the oil / water separator 33. Further, compared to the embodiment of FIG. 1, generally, the solid-liquid separation separator 30 has a lower pressure than the three-phase separator 2, so that the required pressure of the pump 29 can be reduced.

  Unnecessary solid matter in the solid-liquid separation separator 30 is removed from the solid matter outlet 32. Further, the oil 34 obtained by the oil / water separation separator 33 merges with the oil obtained from the three-phase separator 2 and is discharged from the oil outlet 5. Further, the accompanying water obtained from the separator 33 for oil / water separation is discharged from the water outlet 35 and introduced into the rapid stirring tank 9.

  In the second embodiment, the solid-liquid separation separator 30 and the oil / water separation separator 33 are drawn separately. However, a solid, oil, and water can be taken out by one cyclone. Further, instead of this one cyclone, one low-pressure three-phase separator may be used, which will be described in the third embodiment.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected about the same structure as 1st, 2nd embodiment, and duplication description is abbreviate | omitted suitably. In the oil-containing water treatment system 100c (100) of the third embodiment shown in FIG. 3, the low-pressure three-phase separator 36 is installed in the subsequent stage of the three-phase separator 2.

  The difference from the second embodiment shown in FIG. 2 is that a part of or all of the gas taken out from the gas outlet of the low-pressure three-phase separator 36 is passed through the low-pressure three-phase separator 36. It is used as a gas fed into the two-fluid nozzle 25 via the gas pipe 23 and the high-pressure gas flow rate adjusting valve 24. The oil 34 obtained by the low-pressure three-phase separator 36 merges with the oil obtained from the three-phase separator 2 (the illustration of the merge is omitted) and is discharged from the oil take-out port 5.

  With this structure, the running cost can be reduced without the need for newly preparing a high-pressure gas, and the size of the apparatus can be reduced. A part of the gas taken out from the gas outlet 4 of the three-phase separator 2 may be used as the gas fed into the two-fluid nozzle 25.

Although description of this embodiment is finished above, the aspect of the present invention is not limited to these. For example, the present invention can be applied not only to the treatment of accompanying water such as oil and natural gas, but also to other treatments such as industrial wastewater containing oil, and the same effects can be obtained.
In addition, the production of oil from oil sands and the like, and the production of oil from aging oil wells require a large amount of water, and as a result, a large amount of accompanying water is produced. Therefore, the present invention is preferably used. Can do.

The gas used as the high-pressure gas to be fed into the two-fluid nozzle 25 is not limited to air, nitrogen, or natural gas, but may be other gas such as helium or argon as long as it does not cause an adverse chemical reaction such as explosion. There may be.
In addition, about a concrete structure, it can change suitably in the range which does not deviate from the main point of this invention.

1 Liquid to be treated 2 Three-phase separator (oil-water separator)
3 Sill 4 Gas outlet 5 Oil outlet 6 Water outlet 7 Drain valve (solid-liquid separation part)
8 Solid matter outlet (solid-liquid separation part)
9 Rapid stirring tank (aggregation part)
10 Slow stirring tank (aggregation part)
DESCRIPTION OF SYMBOLS 11 Inorganic flocculant tank 12 Magnetic powder tank 13 Polymer flocculant tank 14 Inorganic flocculant injection pump 15 Magnetic powder injection pump 16 Polymer flocculant injection pump 17 Magnetic separation part 18 Magnetic drum 19 Scraper 20 Flock water tank 21 Treated water 22 Flock water transfer pump 23 High-pressure gas piping 24 High-pressure gas flow rate adjustment valve 25 Two-fluid nozzle 26 Magnetic separator (magnetic powder recovery part)
27 Collected magnetic powder return line (return mechanism)
28 Residue return line (return mechanism)
29 Pump (return mechanism)
30 Separator for solid-liquid separation (solid-liquid separation part)
31 Line 32 Solid matter outlet 33 Oil separator separator 34 Oil 35 Water outlet 36 Low pressure three-phase separator 100, 100a, 100b, 100c Oil content water treatment system

Claims (5)

An oil-water separation separator that separates an object to be treated containing oil and water into oil and oil-containing water that is water in which the oil is suspended;
A solid-liquid separation unit for separating and removing solids from the separated oil-containing water;
A flocculant that generates flocs composed of the aggregate of suspended oil and the magnetic powder adhering thereto by adding a flocculant and magnetic powder to the oil-containing water from which the solid matter has been removed; ,
A magnetic separation unit for separating the generated floc from the oil-containing water by magnetic force;
From the separated floc, a magnetic powder recovery unit that recovers magnetic powder by magnetic force,
A return mechanism for returning the floc residue after recovering the magnetic powder in the magnetic powder recovery unit to the upstream side of the solid-liquid separation unit, and returning the magnetic powder recovered in the magnetic powder recovery unit to the aggregation unit When,
An oil-containing water treatment system characterized by comprising: In the oil-containing water treatment system according to claim 1,
An oil-containing water treatment system, wherein the oil-water separation separator and the solid-liquid separation unit are the same device. In the oil-containing water treatment system according to claim 1,
The solid-liquid separation part is arranged at a subsequent stage of the oil-water separation separator,
The oil-containing water treatment system, wherein the residue is returned between the oil-water separation separator and the solid-liquid separation part by the return mechanism. In the oil-containing water treatment system according to any one of claims 1 to 3,
The magnetic powder recovery unit has a structure in which the floc received from the magnetic separation unit is flowed to one nozzle, high-pressure gas is flowed to the other nozzle, and the floc is decomposed by shearing force of the high-pressure gas. An oil-containing water treatment system comprising: a two-fluid nozzle. In the oil-containing water treatment system according to claim 4,
The oil / water separator is a three-phase separator that separates gas from the object to be treated in addition to oil and oil-containing water,
The oil-containing water treatment system is characterized in that a gas taken out from the three-phase separator is used as the high-pressure gas.

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