JPH0560964B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a recovery and regeneration method for obtaining recycled oil by separating and recovering oil from an emulsion-like coolant waste liquid generated in a rolling process, and an apparatus therefor. [Prior Art] Rolling oil used in the rolling process, especially in the hot rolling process, contains oil (neat oil) for the purpose of cooling the rolling rolls and lubrication between the rolling rolls and the material.
It is used in the form of an emulsion, which is a mixture of and water. Therefore, this rolling oil waste liquid (commonly referred to as coolant waste liquid) contains effective oil, but conventionally, this coolant waste liquid has been separated into two layers by standing still or by adding a flocculant to greatly separate oil and water. After separation, the oil goes through a separate treatment process and is often discarded or not reused. [Problem to be Solved by the Invention] A large amount of the above-mentioned coolant waste liquid is generated in rolling mills, but in addition to oil and water, it also contains solid substances such as adjustment additives and metal powder. Because it is a source of environmental pollution, most of it is disposed of by the direct combustion method (a treatment method in which the mixture of water and other substances is forcibly burnt by adding fuel). However, such treatment means are also cumbersome, cause many operational troubles, and have problems such as increased treatment costs, and improvements have been sought. The present invention was made in view of the above circumstances, and
An oil recovery/recovery system that can effectively and inexpensively recover and regenerate the waste oil from rolling oil generated during the rolling process, that is, the oil mixed in coolant waste liquid.
The object of the present invention is to provide a regeneration method and apparatus. [Means for solving the problem] Recovery of oil content from coolant waste liquid according to claim 1.
The regeneration method includes a step of roughly separating the coolant waste liquid into oil and water by adding a flocculant, and extracting only the oil out of the oil and water that have been roughly divided in the previous step, and reducing the oil to 120 to 130% The method is characterized in that recycled oil is obtained through a step of heating the oil to .degree. C. and dehydrating the water remaining in the oil, and cooling the dehydrated oil as it stands. In addition, in the apparatus for recovering and regenerating oil content from coolant waste liquid according to claim 2, in the apparatus for recovering and regenerating oil content from emulsion-like coolant waste liquid generated in a rolling process, a flocculant is added to the coolant waste liquid to remove oil and water. There is a coagulation separation tank which is roughly divided into two, and a coagulation separation tank that heats and
A concentration tank for dehydration and a stationary tank for stationary cooling of the oil dehydrated by the concentration tank are provided, and the concentration tank is connected to a tank body for storing the oil and a pipe inside the tank body. The steam heating pipe is installed so that the passage mainly extends in the vertical direction. Furthermore, in the apparatus for regenerating and recovering oil from coolant waste liquid according to item 3, the steam heating pipe is arranged between two ring pipes vertically spaced apart and arranged substantially horizontally, and the two ring pipes. The apparatus for regenerating and recovering oil from coolant waste liquid according to item 4, characterized by comprising a plurality of vertical pipes disposed almost perpendicularly to the ring pipes and communicating with both ring pipes, The present invention is characterized in that the transfer pump disposed between the tank and the concentration tank is a centrifugal pump such as a centrifugal pump. [Operation] The oil separated from water by the flocculant is stored in the tank body of the concentration tank. The oil is heated by a steam heating tube to a temperature above its boiling point, thereby evaporating the moisture contained therein and dehydrating it. The impurities contained in the dehydrated oil are removed by standing and cooling, and purified recycled oil can be obtained. Furthermore, the evaporation heating tube is arranged such that two ring tubes are vertically spaced apart and arranged substantially horizontally, and a plurality of ring tubes are arranged substantially vertically between the two ring tubes and communicate with each other. When configured with a vertical pipe, sludge is prevented from adhering to the tube surface of the steam heating pipe, and therefore heating can be performed in a short time without reducing the heat exchange rate, and maintenance is easy. Become something. In addition, if the transfer pump placed between the coagulation separation tank and the concentration tank is a centrifugal pump such as a centrifugal pump, the flocs of the water and oil mixture transferred from the coagulation separation tank to the concentration tank will be transferred to the pump. The centrifugal action promotes separation of water and oil. [Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of a coolant waste oil recovery/regeneration apparatus 1 according to the present invention, and shows the overall schematic configuration. In this figure, the reference numeral 3 is a coagulation separation tank, the reference numeral 4 is a concentration tank, and the reference numeral 5 is a stationary cooling tank. In the configuration according to this embodiment, a storage tank 2 is provided upstream of the coagulation separation tank 3 for temporarily storing coolant waste liquid discharged from a rolling mill (not shown) in the hot rolling process. It's summery. In addition, reference numeral 6 in the figure indicates a storage tank 2 through a pump 25.
Coolant waste liquid transfer pipe arranged between the coagulation separation tanks 3, 7 is a transfer pump 26 and a valve 36
A floc (floating oil) transfer pipe arranged between the flocculation separation tank 3 and the concentration tank 4 via A and 36B;
8 is a dehydrated oil transfer pipe arranged between the concentration tank 4 and the stationary tank 5 via a valve 37, a pump 27, and a strainer 40. The storage tank 2
Strainers 2a and 2b for separating solid substances (metal powder, foreign substances, etc.) are attached to the inlet side of the apparatus. The coagulation separation tank 3 is connected to the end of the coolant waste liquid transfer pipe 6, the end of the flocculant injection pipe 9, and the proximal end of the drain pipe 30. Further, the flocculation separation tank 3 is provided with a float suction 10 connected to the base end of the floc transfer pipe 7. The float suction 10 floats on the surface of the liquid (waste coolant liquid) stored in the coagulation separation tank 3 and is always able to suck in the liquid from above. be. Therefore, even if the liquid level falls, it can follow it. The transfer pump 26 is preferably a centrifugal pump with an impeller, and in this embodiment, it is configured as a centrifugal pump. Its effect will be described later. The concentration tank 4 has a tank body 1 for storing the liquid transferred from the coagulation separation tank 3.
1 and a steam heating pipe 12 installed within the tank body 11. In the illustrated example, two concentration tanks 4 are provided, but these two concentration tanks 4 have exactly the same structure, and there may be no problem even if there is only one concentration tank 4. The end of the floc transfer pipe 7 is connected to the upper part of the tank body 11, and the drain pipe 31 is connected to the bottom part of the tank body 11. Further, a rotary type pipe 31 is connected to the bottom of the tank body 11, and a rotary type pipe 31 is connected to the drain pipe 31 at the bottom of the tank body 11. A variable level suction 13 is provided. The rotary level variable suction 13 has a second
As shown in the figure, it is composed of a suction pipe 14 which is bent in a dogleg shape and passes through the tank body 11, and a rotary joint 15 provided at the base end of the suction pipe 14. Since the suction pipe 14 passes through the tank body 11 via the gland packing 16, it is rotatable around the axis of the penetrating portion while maintaining liquid tightness. A base end of the dehydrated oil transfer pipe 8 is connected to the rotary joint 15 . A handle 17 is provided at the proximal end of the suction tube 14 at a position close to the rotary joint 15, and the suction tube 14 can be rotated by the handle 17. Further, an exhaust pipe 19 extends from the top of the tank body 11. This exhaust pipe 19 includes a cooler (water-gas heat exchanger) 42 and a blower 4.
3. Exhaust deodorization equipment 4 consisting of a deodorization tank 44, etc.
5. The deodorizing tank 44 stores an aqueous sodium hydroxide solution, and deodorizes the exhaust air cooled by the cooler 42 by bubbling it in the solution. Note that code 2
0 is a ventilation pipe, and although not shown, an adjustment damper is provided at the tip thereof. The steam heating pipe 1 constituting this concentration tank 4
2 is as shown in FIG. 3, and includes two ring tubes 12a vertically spaced apart and arranged almost horizontally.
and a plurality of vertical pipes 12b arranged almost vertically between the two ring pipes 12a to communicate the two ring pipes 12a, and installed inside and below the tank body 11. ing. A steam supply pipe 21 is connected to the upper ring pipe 12a,
A return pipe 22 is connected to the lower ring pipe 12a, and these steam supply pipe 21 and return pipe 22 penetrate the tank body 11. Reference numeral 41 is a steam trap. The stationary tank 5 stores the liquid (dehydrated oil) transferred from the concentration tank 4 and leaves it stationary, and is connected to the end of the dehydrated oil transfer pipe 8. A refined oil extraction pipe 23 is provided at the bottom, and a drain pipe 32 is provided at the bottom. Further, in this embodiment, the stationary tank 5 is also provided with a steam heating pipe 12' similar to that shown in FIG. An exhaust pipe 19 also extends from the top of the stationary tank 5, and this exhaust pipe 19 is
It merges with the exhaust pipe 19 from the concentration tank 4 and reaches the exhaust deodorizing equipment 45 . Next, an embodiment of the method for recovering and regenerating oil from coolant waste according to the first aspect of the present invention will be described along with the operation of the apparatus 1 for recovering and regenerating oil from coolant waste having the above structure. Coolant waste discharged from a hot rolling mill (not shown) is temporarily stored in the storage tank 2. The coolant waste liquid is an emulsion in which hot rolling oil (water-soluble) and water are mixed together. The coolant waste liquid stored in the storage tank 2 is transferred to the coagulation separation tank 3 by the pump 25 via the coolant waste liquid transfer piping 6. A coagulant is added to the coolant waste liquid through the coagulant injection pipe 9 in the coagulation separation tank 3, and the coolant waste is roughly divided into oil and water. Here, the oil separated from the emulsion becomes what is called a tofu-like substance and floats to the liquid surface. This floating oil is generally called floc. The floc is transferred from the float suction 10 to the floc transfer pipe 7 by a transfer pump 26.
The tank body 11 of the concentration tank 4
is stored in As described above, since the float suction 10 is always located near the liquid surface, it is possible to efficiently collect flocs floating on the liquid surface (while avoiding suction of moisture as much as possible). In addition, the transfer pump 26 may be a spiral pump,
In other words, since it is a centrifugal pump with an impeller, the collected flocs undergo a kind of centrifugal separation action within the pump, promoting separation of water and oil, further improving separation performance within the concentration tank 4. do. In this embodiment, as described above, two concentration tanks 4 are provided, so in this case, by operating the valves 36A and 36B, the liquid is transferred into the tank body 11 of one of the concentration tanks 4. Stores liquid (flock). The water remaining in the coagulation separation tank 3 after the flocs have been removed is sent to the aeration type sewage treatment device 47 via the drain pipe 30. The coagulation separation tank 3
In this case, after draining this residual water, the coolant waste liquid from the storage tank 2 may be received again. Once the floc is stored in the tank body 11 of the concentration tank 4, steam is passed through the steam heating pipe 12 to heat the stored liquid (floc) to about 95°C. However, although the liquid stored in the tank body 11 is floc (oil), it still contains a considerable amount of water, and even when the floc floated to the surface by the float suction 10 is sucked in, only floc is completely absorbed. Of course, it is difficult to collect water, and a relatively large amount of water is also inhaled at the same time, so in addition to oil, the liquid stored in the tank body 11 still contains a considerable amount (about 40%). It will be a mixture of water. As the steam supplied to the steam heating pipe 12, exhaust steam from the equipment system, surplus steam, etc. can be used, and no special heating means (heat source) is required. By heating the steam heating pipe 12, the tank body 11
The liquid inside is separated into oil and water, and the water is separated into two layers, with the water at the bottom of the tank body 11 and the oil at the top. Some of the water in the liquid evaporates at this point. Then, while continuing heating, the valve 38 of the drain pipe 31 is operated to slowly drain the water accumulated at the bottom. At this time, by visually checking the drainage, it is confirmed that the water has been completely discharged and reached the oil layer, and at that point, the valve 38 is closed. The waste water is sent to the aeration type sewage treatment device 47 as in the case of the coagulation separation tank 3 described above. Once the above condition is achieved, heating using the steam heating tube is continued. At this point, the oil remaining in the tank body 11 has had a considerable amount of moisture removed, so the temperature of the liquid in the tank body 11 is
It can be raised to 120-130°C, ie above the boiling point temperature of water. As a result, the water contained in the liquid evaporates, and the stored liquid is dehydrated. Note that here, the heating temperature for the stored liquid is
The reason why the temperature is set at 120 or more is because if it is lower than 120°C, it is possible to evaporate water, but heating and evaporation will take time and the processing efficiency will decrease. On the other hand, the same heating temperature
The reason for setting it below 130°C is that the higher the heating temperature, the more efficient the dehydration operation, but the flash point of the oil separated in this concentration tank 4 is approximately 132°C (see the table below).
For safety reasons, care was taken not to exceed this flash point (however, it will not catch fire as there is no ignition source). The water vapor generated by the dehydration is sent to the exhaust deodorizing equipment 45 through the exhaust pipe 19 and treated together with a small amount of oil (gas) vaporized by heating. Here, the steam heating pipe 1
2, as described above, is mainly composed of a plurality of vertical pipes 12b arranged in the vertical direction as shown in FIG. In addition, since the adhered sludge falls due to gravity, it is naturally detached from the tube surface, and it is possible to prevent problems such as a decrease in heat exchange efficiency due to the adhesion of sludge. In other words, a normal steam heating pipe 50 is generally formed in a meandering arrangement on a horizontal plane as shown in FIG. If the heated material contains impurities (solid content), the sludge or impurity deposits (sediment) may adhere to the tube, and in even worse cases, it may clog the tube, causing heat loss. There are cases where the exchange rate drops significantly, but
According to the steam heating pipe 12, such a problem does not occur, and not only the heat treatment time is shortened, but also
This means that maintenance work such as sludge removal can be reduced as much as possible. In addition, in this embodiment, the steam heating pipe 12 has two ring pipes 12a and 12a, upper and lower, as shown in FIG.
and a vertical pipe 12b that connects these ring pipes 12a, but this steam heating pipe 12 does not necessarily have to have such a construction, and may be arranged so that the steam tube mainly faces in the vertical direction. In this case, the same effects as those described above can be achieved.
However, if the steam heating pipe 12 is configured as described above, the liquid stored in the tank body 11 can be heated uniformly and over a wide range, and efficient heating can be expected. Now, when the dehydration of the stored liquid is completed by the above operation, the dehydrated liquid (dehydrated oil) is transferred to the stationary cooling tank 5 via the dehydrated oil transfer pipe 8, but from the tank body 11 of this dehydrated oil. The extraction is performed via the rotary variable level suction 13. The rotary level variable suction 13 is operated by operating the handle 17 as described above.
By rotating 4, the level of the suction port 14a relative to the liquid level can be set freely, so when removing dehydrated oil, decide how much to remove and calculate (consider) its position from the liquid level. ) to change the position of the suction port. In other words, even in a dehydrated state, the liquid stored in the tank body 11 contains fine impurities, and some of these impurities may settle, so the liquid stored in the tank body 11 should be collected from an upper level if possible. is desirable, and this can be addressed. Once dehydrated oil is generated in the tank body 11 by the concentration tank 4 and by the process, it is transferred to the stationary cooling tank 5 by the pump 27 via the dehydrated oil transfer pipe 8. The liquid transferred to the stationary cooling tank 5 is heated again to a temperature of 120 to 130 DEG C. by the steam heating pipe 12', and subjected to a final dehydration treatment. However, there is no problem even if this re-dehydration operation is omitted, and therefore, in that case, it is not necessary to equip the stationary cooling tank 5 with the steam heating pipe 12'. Once the final dehydration process has been carried out, let the liquid stand and
Cool until the temperature reaches ℃ or higher. This results in
Impurities such as sludge contained inside, fine metal powder mixed in during the rolling process, and metal soap settle downward. After that, refined oil extraction pipe 23
All you have to do is extract the more targeted refined oil (regenerated oil). The reason why the cooling temperature of the liquid is set to 60° C. or lower is that if the temperature is higher than that temperature, there is a risk that the metal soap will not be separated from the refined oil and will be mixed therein. As explained above, according to the apparatus 1 for recovering and regenerating oil content from coolant waste liquid and the method for recovering and regenerating oil content from coolant waste liquid according to the present invention, the oil content contained in coolant waste liquid, which was conventionally disposed of by combustion, can be reliably removed. The recovered oil can be recovered and regenerated, and the obtained regenerated oil can be used as a fuel for dissolving or the like. Incidentally, the properties of the recycled oil obtained in this example are shown below in comparison with the undiluted solution and C heavy oil used in the rolling mill.

【table】

〔Effect of the invention〕

As explained above, according to the method for recovering and regenerating oil from coolant waste liquid according to claim 1, it is possible to roughly separate oil and water using a flocculant, dehydrate oil and fat by heating distillation, and remove fine impurities by standing still. Through this stepwise treatment, the oil contained in the coolant waste liquid can be reliably and efficiently recovered without wasting much of it, and can be recycled as fuel oil or the like. In addition, when dehydrating oil, remove oil to 120%
It is heated to ~130°C, which is lower than the flash point of remanufactured oil from coolant waste liquid, but well above the evaporation temperature of water, which, together with the effect of the stepwise treatment mentioned above, makes oil dehydration safer. This can be done extremely effectively while ensuring that Further, according to the apparatus for recovering and regenerating oil from coolant waste liquid according to claim 2, the method for recovering and regenerating oil from coolant waste liquid according to claim 1 can be effectively realized, and the same effects as described above can be achieved. I can do it.
In addition, since the oil content in the concentration tank is heated by a steam pipe installed inside the tank body, exhaust steam or surplus steam from the equipment system can be used, making it possible to omit a heat source or save energy. It is. Moreover,
As the steam pipes are installed so that they mainly extend in the vertical direction, not only is it difficult for sludge to adhere to the surface of the steam pipes, but the adhered sludge naturally peels off and falls due to gravity, causing the surface of the steam pipes to fall. This prevents a decrease in heat exchange efficiency and significantly reduces maintenance related to sludge removal. Furthermore, according to the apparatus for recovering and regenerating oil from coolant waste liquid according to claim 3, in the dehydration process, the processing time can be shortened by effectively preventing a decrease in the heat exchange rate due to sludge adhesion, and In addition to making maintenance related to the heating tube easier, the liquid stored in the tank body can be heated uniformly and over a wide range, and efficient heating and, by extension, efficient processing can be expected. Furthermore, according to the apparatus for recovering and regenerating oil from coolant waste liquid according to claim 4, the centrifugal action of the pump can promote oil-water separation of the recovered oil in the transfer process, and the oil-water separability in the concentration tank is improved. It is possible to achieve excellent effects such as improving the

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing an embodiment of the oil content recovery and regeneration device of coolant waste liquid according to the present invention, and Fig. 2 is a side view showing the rotary level variable suction according to the present embodiment together with a part of the tank body. 3 is a perspective view showing a steam heating tube according to claim 3 of the present invention, and FIG. 4 is a perspective view showing a general steam heating tube. 1... Oil recovery/regeneration device from coolant waste liquid, 3... Coagulation separation tank, 4... Concentration tank,
5... Stationary tank, 9... Coagulant injection piping, 11
...Tank body, 12...Steam heating pipe, 12a...
...Ring pipe, 12b...Vertical pipe, 26...Transfer pump.

Claims (1)

[Scope of Claims] 1. A method for recovering and regenerating oil from an emulsion-like waste coolant generated in a rolling process, comprising the steps of: roughly separating the waste coolant into oil and water by adding a flocculant; A step of extracting the oil from the oil and water that are roughly classified according to the process, heating the oil to 120 to 130°C, dehydrating the water remaining in the oil, and leaving the dehydrated oil still. A method for recovering and regenerating oil from coolant waste liquid, which comprises a cooling step and obtaining remanufactured oil. 2. In an apparatus for recovering and regenerating oil from emulsion-like waste coolant generated in a rolling process, there is a coagulation separation tank that adds a flocculant to the waste coolant to roughly separate it into oil and water; The concentration tank includes a concentration tank for heating and dehydrating the oil, and a stationary tank for cooling the oil dehydrated by the concentration tank, and the concentration tank has a tank body for storing the oil. 1. An apparatus for recovering and regenerating oil from coolant waste, comprising: a steam heating pipe installed in the tank body so that the pipe line extends mainly in the vertical direction. 3 The steam heating pipes include two ring pipes that are vertically spaced apart and arranged substantially horizontally, and a plurality of steam heating pipes that are arranged substantially vertically between the two ring pipes and communicate with both ring pipes. 3. The apparatus for recovering and regenerating oil from coolant waste liquid according to claim 2, characterized in that it is comprised of a vertical pipe. 4. Claim 2 or 3, wherein the transfer pump disposed between the coagulation separation tank and the concentration tank is a centrifugal pump such as a centrifugal pump.
A device for recovering and regenerating oil from coolant waste liquid as described above.