WO2023243715A1

WO2023243715A1 - Method for operating direct cooling water system, oil content separation promoter, and treatment facility for direct cooling water system

Info

Publication number: WO2023243715A1
Application number: PCT/JP2023/022419
Authority: WO
Inventors: 荻野哲; 加藤雅敏
Original assignee: ナルコジャパン合同会社
Priority date: 2022-06-17
Filing date: 2023-06-16
Publication date: 2023-12-21
Also published as: JP2023184205A

Abstract

Provided is a method for operating a direct cooling water system capable of efficiently separating oil content and suspended matter from direct cooling water that contains oil and metal scale, such as an iron oxide and iron, and of easily recovering the oil content.　The method for operating a direct cooling water system that contains oil and metal scale comprises: causing an oil content separation promoter to be present in wastewater of the direct cooling water system, in a path of turbulent flow from a scale sluice to a scale pit; removing separated floating oil content in a cross-flow settling tank downstream of the scale pit; and recovering and cooling the wastewater from which the oil content was removed in the cross-flow settling tank, and using said wastewater once again as direct cooling water. The cross-flow settling tank is provided with a partitioning weir, and the partitioning weir is disposed inside the cross-flow settling tank with the upper end thereof protruding from the water surface and the lower end thereof being spaced apart from the bottom surface of the cross-flow settling tank, and is provided at a position up to a prescribed depth from the water surface. Flow of the floating oil content is dammed by the partitioning weir, and cooling water wastewater, from which the oil content was separated, is caused to pass between the bottom surface of the cross-flow settling tank and below the lower end of the partitioning weir.

Description

Direct cooling water system operation method, oil separation promoter, and direct cooling water system treatment equipment

The present disclosure relates to a method of operating a so-called direct cooling water system such as spray water in continuous casting or rolling in a steel mill.

In steel mills, a large amount of mill scale is generated due to processing equipment such as direct cooling water used for cooling steel materials during the manufacturing of steel materials. Such scales are mainly metals such as iron oxide and iron generated from steel materials, and metal scales that do not contain oil are useful resources that can be reused in pig iron making, steel making processes, etc. However, during the continuous casting process and rolling process, lubricating oil and rolling oil used in manufacturing machines such as rolling mills mix into cooling water containing scale, so many metal scales are generated. In this case, it contains water and several mass % of oil. Moreover, oil may inevitably be mixed in during work such as recombining the rolling rolls. Each time such an operation is performed, the oil concentration in the scale varies greatly, and specifically, it may vary within a range of 1 to several 10% by mass.

Such direct cooling water is treated with an organic or inorganic flocculant in a scale pit or coagulation-sedimentation facility, and after being cooled, it is reused as cooling water.

As a treatment for such a direct cooling water system, coarse suspended solids (coarse SS) such as metal powder and oil with a particle size of 50 μm or more and fine suspended solids with a particle size of less than 50 μm are treated in the direct cooling water. A technique has been proposed in which fine SS (fine SS) is coagulated and sedimented in the same process and removed at the same time (see Patent Documents 1 to 4). This treatment method attempts to obtain clear treated water by adding a specific polymer to cause oil-containing suspended matter to coagulate and settle in a scale pit and remove it.
In the case of a treatment method in which coarse SS and fine SS containing oil and the like are coagulated and sedimented in the same process, the sludge that accumulates in scale pits and the like contains oil. On the other hand, scales that do not contain oil are useful resources that can be reused in steel manufacturing processes, etc., as described above. Therefore, if the sludge that accumulates in the scale pit contains oil, it is necessary to separate the oil in order to reuse the sludge.

As a method for separating oil from oil-impregnated sludge, for example, there is a method in which an organic solvent is mixed with oil-impregnated sludge as an extractant, and the mixture is strongly stirred to extract oil from oil-impregnated sludge with an organic solvent (see Patent Document 5). On the other hand, since oil-impregnated sludge contains water, such treatment forms a stabilized emulsion.
To break (demulsify) such a stabilized emulsion, a multi-disc centrifuge is required, which is an expensive investment (see Patent Documents 6 and 7).

In addition, oil-impregnated sludge is temporarily stored in sedimentation tanks and thickening layers in steel plants, and must be transported to a treatment facility when it is processed for disposal or as a raw material for steel production. There is. At this time, since oil-impregnated sludge often has a high moisture content and is easily flowable, there is a concern that the oil-impregnated sludge and the oil contained therein may leak out during transportation. Therefore, compared to sludge that does not contain oil and is used as a raw material for steelmaking, oil-impregnated sludge is subject to restrictions such as the amount of transportation and drying. Therefore, it is necessary to make oil-impregnated sludge into a treated material that is easy to transport (Patent Document 8).

Patent No. 6068112 Patent No. 6374157 Patent No. 6374352 Patent No. 6374351 Japanese Patent Application Publication No. 2015-132011 Japanese Patent Application Publication No. 3-238059 Japanese Patent Application Publication No. 2005-349371 JP2019-98327A

In this way, oil-impregnated sludge is subject to limitations not only in its treatment but also in its transportation.
Therefore, the present disclosure efficiently separates oil and other suspended substances from direct cooling water containing oil and metal scales such as iron oxide and iron, suppresses the generation of oil-containing sludge, and To provide a method for operating a direct cooling water system that can easily recover oil.

In one aspect, the present disclosure provides a method for operating a direct cooling water system containing oil and metal scale such as iron oxide or iron, the method comprising:
Presence of an oil separation promoter in the wastewater of the direct cooling water system in the turbulent flow path from the scale sluice to the scale pit;
Removing the separated floating oil in a cross-flow settling tank downstream of the scale pit, collecting the wastewater from which the oil has been removed in the cross-flow settling tank, cooling the collected wastewater, and directly using it as cooling water again. including doing;
The cross-flow sedimentation tank includes a partition weir, and the partition weir is arranged in the cross-flow sedimentation tank with an upper end protruding from the water surface and a lower end spaced apart from the bottom surface of the cross-flow sedimentation tank, and the partition weir allows the The present invention relates to a method of operating a direct cooling water system, in which the flow of floating oil is dammed, and the wastewater from which the oil has been separated is allowed to pass through a spaced apart portion between the lower end of the partition weir and the bottom of the cross-flow settling tank.

In another aspect, the present disclosure relates to a direct cooling water system treatment facility containing oil and metal scale. The processing equipment of the present disclosure includes:
A path forming a turbulent flow state from the scale sluice to the scale pit,
an oil separation promoter supply device for adding an oil separation promoter to the wastewater of the direct cooling water system;
It includes a lateral flow sedimentation tank located downstream of the scale pit and removes separated oil,
The cross-flow settling tank is equipped with a partition weir,
The partition weir has an upper end protruding from the water surface and a lower end separated from the bottom surface of the cross-flow sedimentation tank, so that the flow of the floating oil is dammed by the partition weir, and the lower end of the partition weir and the cross-flow sedimentation tank are separated from each other. It is arranged in the cross-flow sedimentation tank so that the wastewater from which the oil content has been separated can pass through a spaced apart part from the bottom surface of the tank.

In still another aspect, the present disclosure provides an oil separation promoter for carrying out the method of operating a direct cooling water system of the present disclosure, wherein the oil separation promoter is made from a cationic or amphoteric organic coagulant or polymer. This invention relates to an oil separation promoter.

According to the method of the present disclosure, oil is efficiently separated from direct cooling water containing oil and metal scales such as iron oxide and iron, while suppressing the generation of oil-containing sludge and allowing the oil to float to the surface of the water. can be easily collected.
According to the present disclosure, in one or more embodiments, the amount of oil contained in generated sludge can be suppressed. Therefore, according to the present disclosure, in one or more embodiments, oil can be removed from oil-containing sludge, which was necessary in the conventional method of coagulating and settling coarse SS and fine SS containing oil in the same process. This has the advantage that special processing for separating the two is no longer necessary.

FIG. 1 is a schematic diagram showing the configuration of a direct cooling water circulation system in a continuous casting process. 2A and B are drawings for explaining an example of a configuration in which a partition weir is arranged in a cross-flow sedimentation tank, in which FIG. 2A is a plan view seen from the top, and FIG. 2B is a cross-sectional view taken along the line 2A-2A. It is a diagram.

In treating direct cooling water containing oil and metal scale such as iron oxide or iron, the present disclosure provides an oil separation promoter to be added to the cooling water in a turbulent flow path from scale sluice to scale pits. Based on the knowledge that by having a scale pit, the oil can be efficiently separated and the generation of oil-containing sludge can be suppressed, and the separated and floated oil can be easily collected in a cross-flow settling tank equipped with a partition weir downstream of the scale pit. Based on.

According to one aspect of the present disclosure, the flow of the separated floating oil (floating oil) is dammed by a partition weir arranged in a cross-flow settling tank, and the lower end of the partition weir and the cross-flow settling By passing the cooling water wastewater from which the oil has been separated from the bottom of the tank, the treated water can be recovered and cooled, and then used directly as cooling water again.

[Operating method of the present disclosure]
The present disclosure relates to a method of operating a so-called direct cooling water system such as spray water in continuous casting or rolling in a steel mill.
The operating method of the present disclosure includes at least the following (1) to (3).
(1) An oil separation promoter is present in the cooling water in the turbulent flow path from the scale sluice to the scale pit.
(2) In a cross-flow settling tank equipped with a partition weir on the downstream side of the scale pit, the flow of the floating oil is dammed by the partition weir and the oil is removed, and the lower end of the partition weir and the bottom of the cross-flow settling tank are and passing the cooling water from which the oil has been separated.
(3) Collecting the wastewater from which oil has been removed in the cross-flow settling tank, cooling it, and directly using it again as cooling water.

In one or more embodiments, the "direct cooling water system" in the present disclosure refers to a water system that uses cooling water that is directly sprayed onto an object or used to immerse the object by recooling it. The direct cooling water system wastewater and the direct cooling water system wastewater in the present disclosure are cooling water used as direct cooling water, that is, cooling water directly sprayed onto an object or cooling water in which the object was immersed. Direct cooling water wastewater (direct cooling water wastewater) in the present disclosure contains oil and metal scale. In one or more embodiments, the direct cooling water can be directly sprayed or immersed onto steel products such as steel materials and steel plates, rolling rolls, etc. in the continuous casting process or rolling process of a steel mill to cool them. Alternatively, cooling water used for descaling or the like or cooling water that can be used, such as cooling water containing oil and metal scale, can be mentioned. "Direct cooling water" and "cooling water" in the present disclosure may include cooling water used as direct cooling water and cooling water that can be used as direct cooling water.
Examples of the metal scale include iron oxide, iron, and the like in one or more embodiments.

The operating method of the present disclosure includes the presence of an oil separation promoter in the turbulent flow path.
In one or more embodiments, the "turbulent state" in the present disclosure means that the flow or vortex of the cooling water is irregular, or that the flow rate of the cooling water is 0.5 m/s or more. can be mentioned. This is because if the flow rate of the cooling water is 0.5 m/s or more, the water flow or vortex flow of the cooling water containing metal scale becomes irregular.
In one embodiment that is not particularly limited, the "turbulent flow path from the scale sluice to the scale pit" in the present disclosure includes the scale sluice, the scale pit, and the piping between the scale sluice and the scale pit. It will be done.

In one or more embodiments, the scale sluice includes a location where cooling water is directly collected in a continuous casting process or a rolling process. In one or more embodiments, the scale sluice includes a function of discharging, circulating and reusing cooling water recovered from the continuous casting process or rolling process, and oil and metal scale such as iron oxide or iron. It can also function to move cooling water to the outdoor scale pit.

In one or more embodiments, the oil separation promoter is preferably a cationic organic coagulant or polymer or an amphoteric organic coagulant or polymer. In one or more embodiments, the cationic organic coagulant or polymer includes an alkylamine/epichlorohydrin condensate, polyethyleneimine, an alkylene dichloride/polyalkylene polyamine condensate, a dicyandichloride/polyalkylene polyamine condensate, and a polydimethyl Examples include aminoethyl methacrylate and polydiallyldimethylammonium chloride. Examples of the amphoteric organic coagulant or polymer include, in one or more embodiments, a copolymer of trialkylamine and acrylic acid, a copolymer of diallyldimethylammonium chloride and acrylic acid, and the like.

In one or more embodiments, there may be one type of oil separation promoter, or there may be multiple types of oil separation promoters.
In one or more embodiments, the operating method of the present disclosure uses an organic or inorganic flocculant that is commonly used to coagulate and precipitate iron oxide and iron scale in a normal manner, in addition to an oil separation promoter. be able to.
The oil separation promoter used in the operating method of the present disclosure may or may not contain an inorganic flocculant in one or more embodiments.

In one or more embodiments, the amount of the oil separation promoter added is 0.001 mg/L to 5 mg/L, preferably 0.05 mg/L to 5 mg/L.
In one embodiment of the present disclosure, which is not particularly limited, the concentration of the oil separation promoter in the turbulent flow path is 0.001 mg/L to 5 mg/L, preferably 0.001 mg/L to 5 mg/L, in one or more embodiments. 05 mg/L to 5 mg/L.

The operating method of the present disclosure includes removing separated floating oil in a cross-flow settling tank provided with a partition weir downstream of the scale pit.
The partition weir is arranged in the cross-flow sedimentation tank with an upper end protruding from the water surface and a lower end spaced apart from the bottom of the cross-flow sedimentation tank. As a result, the flow of oil (floated oil) that has surfaced by the partition weir is dammed, and the wastewater from which the oil has been separated is allowed to pass between the lower end of the partition weir and the bottom of the cross-flow settling tank (separated portion). Can be done.

In one or more embodiments, recovery (or removal) of the oil whose flow is blocked by the partition weir can be performed using a skimmer, an oil recovery device floated on the water surface of the cross-flow settling tank, or the like. Therefore, in one or more embodiments, the cross-flow sedimentation tank may include a skimmer, an oil recovery device, a recovery tank for storing or processing the recovered oil, and the like.

In one or more embodiments, a cross-flow sedimentation tank (also referred to as a cross-flow coagulation-sedimentation tank) suspends oil and other suspensions during the process (time) in which the water to be treated moves in the longitudinal direction of the tank. Precipitate (or coagulate) a substance. Therefore, from the perspective of improving separation efficiency, the larger the size (especially the length) of the cross-flow sedimentation tank, the better (the longer the better), but from the perspective of equipment investment, etc. It may be determined as appropriate depending on the size of the equipment from which the cooling water system is discharged, the amount of wastewater to be discharged, the size of the place where the cross-flow sedimentation tank is installed, etc.

In one or more embodiments, the partition weir may be arranged perpendicular to the flow direction. In one or more embodiments, the shape of the partition weir is diagonal to the flow direction in order to make the flow of cooling water smooth and to recover and/or separate oil more easily or efficiently. It may be a V-shape in which two plate-like objects extending from the sides of the cross-flow settling tank are arranged so as to close along the flow direction, or it may be a concave shape. 2A and 2B are drawings for explaining an example of arranging the partition weir 10 in the cross-flow sedimentation tank 3. FIG. 2A is an example of a view seen from the top, and FIG. 2B is an example of a view taken along the line 2A-2A. FIG. In FIG. 2A, the partition weir 10 is arranged in a V-shape such that the intersection (apex) of two plate-like objects extending from the side surface of the cross-flow sedimentation tank 3 is located on the downstream side of the cross-flow sedimentation tank 3. As shown in FIGS. 2A and 2B, the cross-flow sedimentation tank 3 includes, in addition to the partition weir 10, an oil recovery device 11 for recovering floated and separated oil, and a sludge drain for recovering suspended solids that have coagulated and settled. A pump 14 may also be provided. In one or more embodiments, the oil recovery device 11 includes a float and is placed floating on the water surface upstream of the partition weir 10. In one or more embodiments, the sludge pump 14 is arranged at the bottom of the cross-flow settling tank 3 upstream of the partition weir 10.

In one or more embodiments, the partition weir may be configured to have a V-shape with two plate-like members extending from the sides of the cross-flow sedimentation tank, as shown in FIG. In order to achieve more efficient separation, the angle (θ) between the two plate-like objects may be arranged to be an acute angle, and the oil contained in the partition weir can be more easily recovered. Therefore, they may be arranged at an obtuse angle. In one or more embodiments, the angle (θ) formed is 30° or more, 40° or more, 50° or more, 60° or more, 70° or more, 80° or more, 90° or more, or 110° or more. In one or more embodiments, the angle (θ) formed is 170° or less, 160° or less, 150° or less, 140° or less, 130° or less, or 125° or less.

In one or more embodiments, the partition weir is arranged in the cross-flow settling tank so that the distance between the water surface and the lower end of the partition weir (d1 in FIG. 2B) is 0.5 m or more. In one or more embodiments, the distance between the water surface and the lower end of the partition weir (d1 in FIG. 2B) is 1 m or more, 1.5 m or more, or 2 m or more. In one or more embodiments, the distance between the water surface and the lower end of the partition weir is 2.5 m or less, or 2 m or less. In one or more embodiments, the partition weir is the distance between the lower end of the partition weir and the bottom of the cross-flow sedimentation tank (the length of the separated part between the lower end of the partition weir and the bottom of the cross-flow sedimentation tank) (d2 in FIG. 2B) is arranged in the cross-flow sedimentation tank so that the distance is 0.5 m or more. In one or more embodiments, the distance between the lower end of the partition weir and the bottom of the cross-flow sedimentation tank (d2 in FIG. 2B) is 1 m or more or 2 m or more. In one or more embodiments, the distance between the lower end of the partition weir and the bottom of the cross-flow sedimentation tank is 3 m or less or 2.5 m or less. In one or more embodiments, the partition weir has a distance (d1) between the water surface and the lower end of the partition weir that is 1/2 or more of the depth of the cross-flow sedimentation tank (distance between the water surface and the cross-flow sedimentation tank: D), They may be arranged so as to be 2/3 or more, or 3/4 or more.

In one or more embodiments, the upper end of the partition weir only needs to protrude (expose) above the water surface to the extent that it can block the flow of floating oil and the oil does not overflow the upper end of the partition weir. In one or more embodiments, the upper end of the partition weir may be exposed 10 cm or more, 30 cm or more, or 50 cm or more from the water surface.

The number of partition weirs is not particularly limited, and in one or more embodiments, it may be one, or two or three or more partition weirs may be arranged in the flow direction of the cross-flow sedimentation tank. Good too.

The location of the partition weir is not particularly limited, and in one or more embodiments, it is 1/2 or less, 1/3 or less, or 1/2 from the downstream end of the cross-flow sedimentation tank toward the upstream side. It can be placed in 4 or less positions.

In one or more embodiments, the operating method of the present disclosure may include collecting suspended substances other than oil (sludge components containing metal scale) precipitated in a cross-flow settling tank. In the operating method of the present disclosure, in one or more embodiments, the oil is floated and separated, so that the suspended matter (sludge component) has a low oil content, and preferably substantially no oil. In the present disclosure, "substantially oil-free" means that the amount of oil in the suspended matter (sludge component) is less than 0.5 mg/L (below the detection limit). In one or more embodiments, the cross-flow sedimentation tank in the operating method of the present disclosure includes a pump (such as a sludge pump) for collecting suspended solids (sludge components), and a sludge collected by the pump for storing or storing the sludge. It may further include a waste sludge collection tank (tank) for processing.

The operating method of the present disclosure includes collecting the wastewater from which oil has been removed in a cross-flow settling tank, cooling it, and directly using it as cooling water again.
In one or more embodiments, the oil-containing wastewater (direct cooling water) treated by the operating method of the present disclosure can be used as direct cooling water in a rolling mill or the like after passing through a filter and a cooling tower.
The operating method of the present disclosure can also be referred to as a direct cooling water treatment method in one or more embodiments. Further, the operating method of the present disclosure can also be referred to as the operation or operating method of the direct cooling water system treatment facility of the present disclosure in one or more embodiments.

[Processing equipment of the present disclosure]
In another aspect, the present disclosure relates to a direct cooling water system treatment facility containing oil and metal scale. The processing equipment of the present disclosure includes:
A path forming a turbulent flow state from the scale sluice to the scale pit,
an oil separation promoter supply device for adding an oil separation promoter to the wastewater of the direct cooling water system;
A cross-flow sedimentation tank that is placed downstream of the scale pit and removes separated floating oil,
The cross-flow settling tank is equipped with a partition weir,
The partition weir is disposed in the cross-flow sedimentation tank with an upper end protruding from the water surface and a lower end spaced apart from the bottom surface of the cross-flow sedimentation tank, and the flow of the floating oil is dammed by the partition weir, and The wastewater from which the oil has been separated can pass between the lower end of the partition weir and the bottom surface of the cross-flow settling tank. According to the processing equipment of the present disclosure, the method of operating a direct cooling water system of the present disclosure can be performed efficiently.

In the processing equipment of the present disclosure, the path for forming a turbulent flow state from the scale sluice to the scale pit, the equipment incidental thereto, such as the cross-flow sedimentation tank and the partition weir, are the same as the operating method of the present disclosure.

[Oil separation promoter of the present disclosure]
In still another aspect, the present disclosure provides an oil separation promoter for carrying out the method of operating a direct cooling water system of the present disclosure, wherein the oil separation promoter is made from a cationic or amphoteric organic coagulant or polymer. This invention relates to an oil separation promoter.
The cationic or amphoteric organic coagulant or polymer in the oil separation promoter of the present disclosure is the same as the operating method of the present disclosure.

A non-limiting embodiment of the present disclosure will be described with reference to FIG. 1. One embodiment of the operating method of the present disclosure includes the following (1) to (4).
(1) In scale sluice 1, an amphoteric organic coagulant or polymer is added to the direct cooling water system wastewater.
(2) In the scale pit 2, a cationic organic coagulant or polymer and an inorganic coagulant are added directly to the cooling water system wastewater.
(3) In the cross-flow sedimentation tank 3 equipped with a partition weir, the oil in the wastewater to which the chemical has been added is suspended, and other suspended substances (sludge components) are coagulated and precipitated.
(4) Collect the wastewater from which oil has been removed, cool it, and use it again as direct cooling water.
Each step of (1) to (4) will be explained in detail below.

(1) In the scale sluice 1, an amphoteric organic coagulant or polymer is directly added to the cooling water system wastewater using the chemical addition device 7.
In one or more embodiments, the amount of the amphoteric organic coagulant or polymer added is 0.001 mg/L to 5 mg/L, preferably 0.05 mg/L to 5 mg/L. Further, in one or more embodiments, the concentration of the amphoteric organic coagulant or polymer in the wastewater in the scale sluice is 0.001 mg/L to 5 mg/L, preferably 0.05 mg/L to 5 mg/L. It is L.

(2) In the scale pit 2, a cationic organic coagulant or polymer and an inorganic coagulant are directly added to the cooling water system wastewater using a chemical addition device (not shown).
The cationic organic coagulant or polymer and the inorganic coagulant may be added separately, or may be added as a mixture. The cationic organic flocculant or polymer and the inorganic coagulant may be added at the same position in the scale pit or at different positions.
In one or more embodiments, the amount of the cationic organic flocculant or polymer added is 0.001 mg/L to 5 mg/L, preferably 0.05 mg/L to 5 mg/L. Further, in one or more embodiments, the concentration of the cationic organic flocculant or polymer in the wastewater in the scale sluice is 0.001 mg/L to 5 mg/L, preferably 0.05 mg/L to 5 mg. /L.
In one or more embodiments, the inorganic coagulant includes polyaluminum chloride (PAC), aluminum sulfate, aluminum chloride, ferric chloride, ferric sulfate, polyferric sulfate, and the like. In one or more embodiments, the amount of the inorganic coagulant added is 0.001 mg/L to 20 mg/L, preferably 0.1 mg/L to 10 mg/L. Further, in one or more embodiments, the concentration of the inorganic coagulant in the wastewater in the scale sluice is 0.001 mg/L to 20 mg/L, preferably 0.1 mg/L to 10 mg/L.

(3) In the cross-flow sedimentation tank 3 equipped with a partition weir, the oil in the wastewater to which the chemical has been added is suspended, and other suspended substances (sludge components) are coagulated and precipitated.
The oil content in the wastewater to which the drug has been added and introduced into the cross-flow sedimentation tank 3 is separated from the wastewater and floats to the water surface. The flow of the floating oil (floating oil) is dammed up by a partition weir installed in the cross-flow settling tank. The dammed oil can be easily recovered using, for example, a skimmer or an oil recovery device placed above the water surface. Further, suspended substances (sludge components) other than oil are coagulated and precipitated in the cross-flow sedimentation tank 3, and can be recovered using a sludge pump or the like, for example. Therefore, wastewater from which oil and other suspended substances have been removed can be passed between the lower end of the partition weir and the bottom of the cross-flow sedimentation tank.

(4) Collect wastewater from which oil has been removed, cool it, and use it directly as cooling water again.

In the above embodiment, an amphoteric organic coagulant or polymer is added in the scale sluice 1, and a cationic organic coagulant or polymer and an inorganic coagulant are added in the scale pit 2. The types of chemicals used in the operating method and the positions at which they are added are not limited to these.

The present disclosure further relates to one or more embodiments below.
[1] A method for operating a direct cooling water system containing oil and metal scale, comprising:
Presence of an oil separation promoter in the wastewater of the direct cooling water system in the turbulent flow path from the scale sluice to the scale pit;
Removing the separated floating oil in a cross-flow sedimentation tank downstream of the scale pit, and collecting the wastewater from which the oil has been removed in the cross-flow sedimentation tank, cooling it and directly using it as cooling water,
The cross-flow sedimentation tank includes a partition weir, and the partition weir is arranged in the cross-flow sedimentation tank with an upper end protruding from the water surface and a lower end spaced apart from the bottom surface of the cross-flow sedimentation tank, and the partition weir allows the damming the flow of floating oil, and allowing the wastewater from which the oil has been separated to pass through a spaced apart portion between the lower end of the partition weir and the bottom of the cross-flow settling tank;
How to operate a direct cooling water system.
[2] The method according to [1], wherein the partition weir is arranged obliquely or in a V-shape with respect to the flow direction of the cross-flow settling tank.
[3] The method according to [1] or [2], wherein the oil separation promoter is a cationic or amphoteric organic coagulant or polymer.
[4] The cationic organic coagulant or polymer may be alkylamine/epichlorohydrin condensate, polyethyleneimine, alkylene dichloride/polyalkylenepolyamine condensate, dicyandichloride/polyalkylenepolyamine condensate, polydimethylaminoethyl methacrylate, or The method according to [3], which is one or more organic coagulants or polymers selected from diallyldimethylammonium chloride.
[5] Direct cooling according to [3] or [4], wherein the amount of the cationic organic flocculant or polymer added is 0.001 mg/L to 5 mg/L or 0.05 mg/L to 5 mg/L. How to operate a water system.
[6] The amphoteric organic coagulant or polymer is one or more organic coagulants or polymers selected from a copolymer of trialkylamine and acrylic acid and a copolymer of diallyldimethylammonium chloride and acrylic acid. 3] to [5].
[7] The amount of the amphoteric organic coagulant or polymer added is 0.001 mg/L to 5 mg/L or 0.05 mg/L to 5 mg/L, according to any one of [3] to [6]. Method.
[8] The method according to any one of [1] to [7], which comprises causing an inorganic coagulant to be present in the wastewater of the direct cooling water system in the turbulent flow path from the scale sluice to the scale pit. .
[9] The inorganic coagulant is selected from the group consisting of polyaluminum chloride (PAC), aluminum sulfate, aluminum chloride, ferric chloride, ferric sulfate, and polyferric sulfate, according to [8]. the method of.
[10] The amount of inorganic coagulant added is 0.001 mg/L to 20 mg/L, 0.01 mg/L to 20 mg/L, 0.1 mg/L to 20 mg/L, 0.001 mg/L to 10 mg/L. or 0.1 mg/L to 10 mg/L, the method according to [8] or [9].
[11] The method according to any one of [1] to [10], which comprises adding an amphoteric organic coagulant or polymer to the scale sluice.
[12] Adding amphoteric organic coagulants or polymers to the wastewater of the scale sluice such that the concentration of the amphoteric organic coagulant or polymer in the wastewater of the scale sluice is 0.001 mg/L to 5 mg/L or 0.05 mg/L to 5 mg/L. The method according to any one of [1] to [11], which comprises adding an organic coagulant or polymer.
[13] The method according to any one of [1] to [12], which includes adding a cationic organic coagulant or polymer and an inorganic coagulant to the scale pit.
[14] Add to the wastewater of the scale pit so that the concentration of the cationic organic coagulant or polymer in the wastewater of the scale pit is 0.001 mg/L to 5 mg/L or 0.05 mg/L to 5 mg/L. The method according to any one of [1] to [13], which comprises adding a cationic organic coagulant or polymer.
[15] The concentration of the inorganic flocculant in the wastewater in the scale pit is 0.001 mg/L to 20 mg/L, 0.01 mg/L to 20 mg/L, 0.1 mg/L to 20 mg/L, 0.001 mg/L. The method according to any one of [1] to [14], which comprises adding an inorganic flocculant to the wastewater of the scale pit so that the concentration is L ~ 10 mg/L or 0.1 mg/L ~ 10 mg/L.
[16] Direct cooling water system treatment equipment containing oil and metal scale,
A path forming a turbulent flow state from the scale sluice to the scale pit,
an oil separation promoter supply device for adding an oil separation promoter to the wastewater of the direct cooling water system;
A cross-flow sedimentation tank that is placed downstream of the scale pit and removes separated floating oil,
The cross-flow settling tank is equipped with a partition weir,
The partition weir has an upper end protruding from the water surface and a lower end separated from the bottom surface of the cross-flow sedimentation tank, so that the flow of the floating oil is dammed by the partition weir, and the lower end of the partition weir and the cross-flow sedimentation tank are separated from each other. A direct cooling water system treatment facility disposed within the cross-flow sedimentation tank so that the wastewater from which the oil content has been separated can pass through a space between the tank and the bottom surface of the tank.
[17] An oil separation promoter for carrying out the method of operating a direct cooling water system according to any one of [1] to [15],
The oil separation promoter is made of a cationic or amphoteric organic coagulant or polymer.
[18] The cationic organic coagulant or polymer may be alkylamine/epichlorohydrin condensate, polyethyleneimine, alkylene dichloride/polyalkylenepolyamine condensate, dicyandichloride/polyalkylenepolyamine condensate, polydimethylaminoethyl methacrylate, or The oil separation promoter according to [17], which is one or more organic coagulants or polymers selected from diallyldimethylammonium chloride.
[19] The amphoteric organic coagulant or polymer is one or more organic coagulants or polymers selected from a copolymer of trialkylamine and acrylic acid and a copolymer of diallyldimethylammonium chloride and acrylic acid, [ 17] or the oil separation promoter according to [18].

Hereinafter, the present disclosure will be further explained using Examples. However, this disclosure is not to be construed as being limited to the following examples.

A treatment for removing sludge components was performed in a direct cooling water circulation system (circulated water amount: 1400 m ³ /h) of a continuous casting process as shown in FIGS. 1 and 2. The direct cooling water circulation system shown in FIG. 1 includes a scale sluice 1, a scale pit 2, a cross-flow sedimentation tank 3, a filter 4, and a cooling tower 5. Cooling water used for cooling the steel material in the rolling process is introduced into the scale pit 2 through a pipe (trough, gutter) 6 from a scale sluice 1 provided below the steel material rolling line. The scale sluice 1 includes a drug addition device 7. The cross-flow settling tank 3 includes a partition weir 10, an oil recovery device 11, an oil recovery tank (tank) 8, a sludge pump 14, and a sludge recovery tank (tank) 9, and the oil recovered by the oil recovery device 11 is an oil component. Suspended substances (sludge components) stored in a recovery tank (tank) 8 and recovered by a sludge pump 14 are collected in a sludge recovery tank (tank) 9.

The treatment for removing sludge components was carried out for two months using the following procedure.
scale sleuth 1
・Oil separation promoter to be added: Copolymer of diallyldimethylammonium chloride and acrylic acid (weight average molecular weight: approximately 400,000, manufactured by Nalco Company)
・Amount added: 0.5mg/L to circulating water
scale pit 2
・Drug added: PAC (polyaluminum chloride) 6mg/L
Cationic organic flocculant (manufactured by Katayama Chemical Industry Research Institute Co., Ltd., trade name "Floclan (registered trademark) SC-640") 1 mg/L
As mentioned above, in the scale sluice 1, an oil separation promoter is added to the circulating water before oil separation, in the scale pit 2, the above-mentioned PAC and cationic organic flocculant are added, and in the cross-flow settling tank 3, the oil is suspended. , and other suspended substances (sludge components) were coagulated and precipitated.
A V-shaped partition weir (distance between the water surface and the bottom end (d2): 1 m, distance between the water surface and the top end: 30 cm, θ: 120°) is installed in the cross-flow sedimentation tank 3 on the downstream side of the scale pit 2, and the cross-flow sedimentation tank The cooling water from which the oil has been separated is passed between the lower end of the partition weir and the bottom of the cross-flow sedimentation tank 3. .
Test water was collected from near the water surface on the upstream side of the partition weir and near the water surface on the downstream side of the partition weir, and the oil content contained in the test water was measured by the N-hexane extractable substance measurement method based on JIS K 0102.
The oil content of the test water collected from near the water surface on the upstream side of the partition weir 10 (▽12 in Figure 2A) remained at a maximum value of 52 mg/L, a minimum value of 15 mg/L, and an average value of 35 mg/L. The oil content of the test water collected from near the water surface on the downstream side of the partition weir 10 (▽13 in Figure 2A) had a maximum value of 3.5 mg/L, a minimum value of less than 0.5 mg/L, and an average value of 0.7 mg/L. It has changed.
Moreover, the oil content of the sludge coagulated and precipitated in the cross-flow settling tank 3 was not detected (less than 0.5 mg/L).
As is clear from these results, by implementing the operating method of the present disclosure, oil can be efficiently separated from direct cooling water containing oil and iron oxide and metal scale such as iron, and the treated treated water can be effectively separated. The sludge can be cooled as it is and used directly as cooling water, and has the effect of suppressing the amount of oil contained in the generated sludge.

Claims

A method of operating a direct cooling water system containing oil and metal scale, the method comprising:
Presence of an oil separation promoter in the wastewater of the direct cooling water system in the turbulent flow path from the scale sluice to the scale pit;
Removing the separated floating oil in a cross-flow settling tank downstream of the scale pit, collecting the wastewater from which the oil has been removed in the cross-flow settling tank, cooling the collected wastewater, and directly using it as cooling water again. including doing;
The cross-flow sedimentation tank includes a partition weir, and the partition weir is arranged in the cross-flow sedimentation tank with an upper end protruding from the water surface and a lower end spaced apart from the bottom surface of the cross-flow sedimentation tank, and the partition weir allows the damming the flow of floating oil, and allowing the wastewater from which the oil has been separated to pass through a spaced apart portion between the lower end of the partition weir and the bottom of the cross-flow settling tank;
How to operate a direct cooling water system.
The method according to claim 1, wherein the partition weir is arranged obliquely or in a V-shape with respect to the flow direction of the cross-flow settling tank.
The method according to claim 1 or 2, wherein the oil separation promoter is a cationic or amphoteric organic coagulant or polymer.
The cationic organic coagulant or polymer is an alkylamine/epichlorohydrin condensate, polyethyleneimine, an alkylene dichloride/polyalkylene polyamine condensate, a dicyandichloride/polyalkylene polyamine condensate, polydimethylaminoethyl methacrylate, and polydiallyldimethyl. 4. The method of claim 3, wherein the organic coagulant or polymer is selected from the group consisting of ammonium chloride.
The amphoteric organic coagulant or polymer is one or more organic coagulants or polymers selected from the group consisting of a copolymer of trialkylamine and acrylic acid and a copolymer of diallyldimethylammonium chloride and acrylic acid. The method according to claim 3.
A direct cooling water system treatment facility containing oil and metal scale,
A path forming a turbulent flow state from the scale sluice to the scale pit,
an oil separation promoter supply device for adding an oil separation promoter to the wastewater of the direct cooling water system;
A cross-flow sedimentation tank that is placed downstream of the scale pit and removes separated floating oil,
The cross-flow settling tank is equipped with a partition weir,
The partition weir has an upper end protruding from the water surface and a lower end separated from the bottom surface of the cross-flow sedimentation tank, so that the flow of the floating oil is dammed by the partition weir, and the lower end of the partition weir and the cross-flow sedimentation tank are separated from each other. A direct cooling water system treatment facility disposed within the cross-flow sedimentation tank so that the wastewater from which the oil content has been separated can pass through a space between the tank and the bottom surface of the tank.
An oil separation promoter for carrying out the method for operating a direct cooling water system according to any one of claims 1 to 5, comprising:
The oil separation promoter is made of a cationic or amphoteric organic coagulant or polymer.
The cationic organic coagulant or polymer is an alkylamine/epichlorohydrin condensate, polyethyleneimine, an alkylene dichloride/polyalkylene polyamine condensate, a dicyandichloride/polyalkylene polyamine condensate, polydimethylaminoethyl methacrylate, and polydiallyldimethyl. The oil separation promoter according to claim 7, which is one or more organic coagulants or polymers selected from the group consisting of ammonium chloride.
The amphoteric organic coagulant or polymer is one or more organic coagulants or polymers selected from the group consisting of a copolymer of trialkylamine and acrylic acid and a copolymer of diallyldimethylammonium chloride and acrylic acid. The oil separation promoter according to claim 7.