JP2019025478A - Method and apparatus for processing cutting oil waste liquid - Google Patents

Abstract

To provide a method and apparatus for processing cutting oil waste liquid in which cutting oil waste liquid can be purified to a state substantially free of oil content, oil content in cutting oil waste liquid can be separated and recovered as oil of low water content as well as said processing can be implemented with simple equipment.SOLUTION: Provided is a method for processing cutting oil waste liquid characterized by including: a membrane filtration separation step of separating into high concentration oil content and oil content free water in a cutting oil waste liquid by membrane filtration treatment; a centrifuge separation step of centrifuge separating the high concentration oil content to separate into oil content, water and solid; and a demulsifier adding step of adding a demulsifier before the membrane filtration separation step or the centrifuge separation step.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a processing method and a processing apparatus for cutting oil waste liquid.

  Conventionally, biological treatment, evaporation treatment, membrane filtration treatment, centrifugal separation treatment and the like have been used for treatment of wastewater containing oil. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2010-58019) discloses a method for treating an emulsion-type water-soluble cutting oil. After adjusting the emulsion-type water-soluble cutting oil to a pH of less than 5, polyacrylic acid is added. The cutting oil waste liquid is divided into a step of separating into an upper layer containing cutting oil and a lower layer containing a surfactant, a step of ultrafiltration treatment of the lower layer, and a step of reverse osmosis membrane treatment of the ultrafiltered solution. A method of processing is described.

  Patent Document 2 (Japanese Patent Laid-Open No. 2015-199848) “Recycled Heavy Oil Production Method and Production System” includes a flotation separation process in which waste oil containing moisture is heated to 40 to 60 ° C. and separated into two layers, and flotation A two-stage solid / liquid separation process for removing solids from the liquid obtained in the separation process, and a liquid obtained in the solid / liquid separation process is heated to 80 to 100 ° C. A low water content of less than 1% by weight from waste oil containing water by a three-phase separation process that separates the liquid and sludge and a water evaporation process that heats and stirs the light liquid to 100 to 110 ° C. and evaporates the water. A treatment method for obtaining recycled heavy oil with a moisture content is described.

JP 2010-58019 A JP-A-2015-199848

  However, in the technique of Patent Document 1, since the moisture content of the oil-containing sludge aggregated with polyacrylic acid is high and difficult to dehydrate, it is difficult to reuse as fuel oil or the like. Moreover, in the technique of Patent Document 2, since a total of five steps of separation steps are required, the apparatus becomes large-scale and maintenance is complicated. In addition, since a total of three heating steps are required, the amount of energy required for the treatment is large. And in order to purify the treated water separated in each process, it was necessary to provide a separate process.

  The present invention has been made in view of the above-described conventional problems, and its purpose is to purify cutting oil waste liquid to a state in which oil is hardly contained, and to separate oil in cutting oil waste liquid as low moisture content oil. -It is providing the processing method and processing apparatus of the cutting oil waste liquid which can be collect | recovered and can implement these processes with simple equipment.

  In one aspect, the present invention provides a membrane filtration separation step for separating a high concentration of oil in cutting oil waste liquid and water that does not contain oil by a membrane filtration treatment, and separating oil and water by centrifuging the high concentration of oil. There is provided a method for treating a cutting oil waste liquid, comprising: a centrifugal separation step for separating into a solid substance; and a demulsifier addition step for adding a demulsifier before the membrane filtration separation step or the centrifugal separation step. .

  The processing method of the cutting oil waste liquid which concerns on this invention in one embodiment WHEREIN: A cutting oil waste liquid is 30 degreeC-65 degreeC at the time of the addition of a demulsifier in a demulsifier addition process, or before or after addition. It has a heating process of heating.

  In still another embodiment of the method for treating a cutting oil waste liquid according to the present invention, the cutting oil waste liquid contains a water-soluble cutting oil.

  In still another embodiment of the method for treating a cutting oil waste liquid according to the present invention, the demulsifier is water-soluble.

  In another aspect of the present invention, a heating means for heating the cutting oil waste liquid, and a cutting oil waste liquid before or after heating by the heating means are introduced, and the cutting oil waste liquid in the cutting oil waste liquid is subjected to membrane filtration treatment. Membrane filtration means for separating high-concentration oil (concentrated oil-containing waste liquid) and non-oil-containing water (treated water), return means for returning high-concentration oil to the heating means, and heating by the heating means Centrifugation means for separating the cutting oil waste liquid after warming and separating it into oil, water and solids by centrifugation, and addition of a demulsifier to the cutting oil waste liquid before or after the heating means An apparatus for treating a cutting oil waste liquid comprising means is provided.

  According to the present invention, it is possible to purify the cutting oil waste liquid to a state in which the oil content is substantially not contained, and to separate and recover the oil having a low water content such that almost the entire oil content in the cutting oil waste liquid can be reused as fuel oil, and The processing method and processing apparatus of the cutting oil waste liquid which can implement these processes with simple equipment can be provided.

It is a schematic diagram which shows an example of the processing apparatus which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows an example of the processing apparatus which concerns on the 2nd Embodiment of this invention. It is a schematic diagram which shows an example of the processing apparatus which concerns on the 3rd Embodiment of this invention.

  Hereinafter, first to third embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. The following embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention describes the structure, arrangement, etc. of components as follows. It is not something specific.

(First embodiment)
A processing apparatus according to a first embodiment of the present invention will be described with reference to FIG. The cutting oil waste liquid is not particularly limited as long as it is a waste liquid containing cutting oil. For example, a waste liquid containing water-soluble cutting oil can be suitably used. In addition, although this embodiment demonstrates the case where a cutting oil waste liquid is processed as an example, if it is not only a cutting oil waste liquid but the waste liquid containing oil, ie, an oil-containing waste liquid, with the processing object (raw water) of this embodiment, can do. As the oil-containing waste liquid, waste liquid containing various oils such as heavy oil, light oil and crude oil can be treated. In the following description, an example of processing an oil-containing waste liquid will be described.

  This oil-containing waste liquid is introduced from the raw water tank 1 into the membrane filtration treatment means 2 having a microfiltration membrane or an ultrafiltration membrane as a separation membrane using a pressure pump 5 to obtain treated water that has permeated the membrane. The oil-containing wastewater that has not permeated the membrane is returned to the raw water tank 1 as a circulating liquid through the return pipe 21. The above treatment is carried out until the oil-containing waste liquid is concentrated to a certain fixed concentration or higher.

  A demulsifier is added to and mixed with the concentrate concentrated to a certain concentration. In the example of FIG. 1, the circulating liquid is returned to the raw water tank 1, and the demulsifier is added to the raw water tank 1 to obtain a mixed liquid in which the demulsifier is mixed with the concentrated liquid. The addition position is not limited to this. It should be noted that the amount of demulsifier added varies depending on the type of demulsifier and the nature of the water to be treated, so it is desirable to confirm the optimum amount in advance. It can add so that it may become 100 ppm or more. Although the upper limit value of the demulsifier to be added is not limited to the following for the same reason as described above, it can be added to, for example, 5000 ppm or less, further 1000 ppm or less with respect to the water to be treated.

  A demulsifier is added and mixed from the demulsifier adding means to the oil-containing waste liquid returned to the raw water tank 1. When the demulsifier is added and mixed, the oil-containing waste liquid in the raw water tank 1 is preferably heated to 30 ° C to 65 ° C. When the oil-containing waste liquid is heated to 30 ° C. to 65 ° C., the viscosity of the oil-containing waste liquid is lowered, so that an effect that oil-water separation can be performed more efficiently can be expected. If the oil-containing waste liquid is heated too much, the energy efficiency of the entire processing apparatus deteriorates, and depending on the components of the oil in the waste liquid, the flash point may be exceeded. It is below ℃.

  The mixed liquid obtained by mixing the demulsifier with the concentrated liquid is introduced into the heater 3 through the steam pipe 11 and heated. The heater 3 is connected to a steam generation boiler (not shown) or connected to an electric heater. The heater 3 is provided with a circulation pipe 31 for feeding back the heated waste liquid flowing out to the raw water tank 1, and a circulation pump (not shown) is provided in the middle of the circulation pipe 31.

  The mixed liquid heated in the heater 3 is centrifuged in the centrifugal separator 4 and separated into a heavy liquid mainly composed of oil, a light liquid mainly composed of water (oil-containing water), and a solid matter. Discharged. Since the oil-containing water after centrifugation contains oil, it is returned to the raw water tank 1 via the return pipe 41 and processed again. Here, when a water-soluble demulsifier is used, the demulsifier remains in the oil-containing water. Therefore, the demulsifier can be reused by returning the demulsifier to the raw water tank 1 and mixing it with the oil-containing waste liquid. It becomes. Examples of the water-soluble demulsifier include an anionic surfactant, a cationic surfactant, a nonionic surfactant, an anionic polymer, a cationic polymer, an amphoteric polymer, and a phenol derivative. The oil-containing waste liquid heated by the heater 3 is provided with a mixing tank (not shown) instead of feeding back to the raw water tank 1, and after adding and mixing the demulsifier in the mixing tank, the mixed liquid is heated to the heater 3 Alternatively, it can be introduced into the centrifuge 4.

  According to the processing apparatus which concerns on 1st Embodiment, oil-containing waste liquid can be refine | purified to the state which does not substantially contain oil content with a simple system, and low moisture content oil can be isolate | separated and collect | recovered. Moreover, the treated water obtained in the first embodiment can be drained into the sewer by performing secondary treatment such as biological treatment.

  Moreover, according to the processing apparatus which concerns on 1st Embodiment, by adding a demulsifier with respect to an oil-containing waste liquid in the front | former stage of a membrane filtration isolation | separation process, compared with the membrane filtration process without a demulsifier addition, Since the membrane clogging can be alleviated, the treatment can be performed stably, and the cost for membrane replacement and membrane cleaning can be reduced. Furthermore, by applying heat treatment to the oil-containing waste liquid before the membrane filtration separation process, the viscosity of the liquid is reduced, so that the flux of the membrane filtration process can be improved, and the membrane area required for the membrane filtration process can be reduced. It is possible to simplify the apparatus.

  The demulsifier can be added before the membrane filtration treatment. In that case, demulsification of the oil-containing waste liquid occurs during the concentration of the oil-containing waste liquid by membrane filtration. Therefore, it is possible to expect an effect that the membrane blockage is alleviated during the membrane filtration treatment and the membrane permeation flux is improved.

(Second Embodiment)
In the processing apparatus according to the second embodiment, as shown in FIG. 2, the heater 3 is provided on the upstream side of the membrane filtration means 2. Other configurations are the same as those of the processing apparatus according to the first embodiment shown in FIG.

  In the processing apparatus according to the second embodiment, since the oil-containing waste liquid is heated by the heater 3 before the membrane filtration treatment, the viscosity is reduced and the permeation flux in the membrane filtration treatment is improved. Therefore, the number of membranes used in the membrane filtration means 2 can be reduced, or the treatment can be performed in a shorter time. In addition, since the membrane filtration treated water retains the amount of heat, the amount of heat can be recovered using a heat exchanger (not shown). Other operations and effects are the same as those of the processing apparatus according to the first embodiment.

(Third embodiment)
In the treatment apparatus according to the third embodiment, as shown in FIG. 3, the heater 3 is provided on the upstream side of the raw water tank 1. Other configurations are the same as those of the processing apparatus according to the second embodiment shown in FIG. 2, and the same operations and effects as those of the processing apparatus shown in FIG. 2 are obtained.

  In the processing apparatus according to the third embodiment, the oil-containing waste liquid is heated by the heater 3 before adding / mixing the demulsifier, so that the viscosity of the oil in the oil-containing waste liquid is increased before adding the demulsifier. The demulsifier can be mixed and dispersed in the raw water tank 1 smoothly and in a short time. Other operations and effects are the same as those of the processing apparatus according to the first embodiment or the second embodiment.

  Examples of the present invention will be described below together with comparative examples, but these examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention.

Example 1
Using the processing apparatus shown in FIG. 3, the water-soluble cutting fluid waste liquid discharged from the factory was used as test raw water and concentrated to about 15 times (volume ratio) using an ultrafiltration membrane (fractionated molecular weight of 300,000). . Next, after heating the concentrated liquid to 50 ° C., a demulsifier (Hakutol E-523, manufactured by Hakutosha) was added and mixed at a rate of 1000 mg per kg of the concentrated liquid, and this was introduced into a centrifuge. It separated into three phases: water, oil and solid.

  The water content of the oil-containing waste liquid raw water, the concentrated liquid after the membrane filtration separation process, and the centrifugal recovery oil is CA-200 manufactured by Mitsubishi Chemical Analytech, and the calorific value of the centrifugal recovery oil is CA-4AJ manufactured by Shimadzu Corporation. Each was measured.

  As shown in Table 1, the normal hexane extract substance concentration of the treated water after the membrane filtration separation step was 3.0 mg / L, and the oil concentration could be reduced to water quality that could be discharged into the sewer. On the other hand, the water content of the concentrate was 30.4%, but it was difficult to reduce the water content further only by the membrane filtration separation step.

  The recovered oil after centrifugation of the concentrate had a water content of 0.88% and a calorific value of 40.8 MJ / kg, almost equal to that of heavy oil. The oil-containing water generated in the centrifugal separation process was returned to the raw water tank and treated again to recover the oil content.

(Example 2)
About the test raw water similar to Example 1, the same demulsifier as Example 1 was added and mixed with respect to test raw water in the ratio of 500 mg per kg of test raw water, and this was the ultrafiltration membrane similar to Example 1 And concentrated to about 15 times (volume ratio). Next, the concentrate was heated to 50 ° C. and then introduced into a centrifuge to separate into three phases of water, oil and solid.

  As shown in Table 2, the normal hexane extract substance concentration of the treated water after the membrane filtration separation step was 5.0 mg / L, and the oil concentration could be reduced to the water quality that could be discharged into the sewer. On the other hand, the water content of the concentrated liquid was 26.5%, but it is difficult to reduce the water content further only by the membrane filtration separation step. The water content of the recovered oil after the centrifugal separation treatment of the concentrate was 0.92%, and the calorific value was 39.5 MJ / kg. Similar to Example 1, the heat generated by the centrifugally recovered oil was almost the same as that of heavy oil. The oil-containing water generated in the centrifugal separation process was returned to the raw water tank and treated again to recover the oil content.

  Table 3 shows the results of measuring the fresh water flux with respect to the membrane after the membrane filtration separation treatment in Example 1 and the membrane after the membrane filtration separation treatment in Example 2, and the ratio to the fresh water flux before the test. It showed in. From Table 3, it can be seen that Example 2 with the addition of the demulsifier had a higher fresh water flux ratio than Example 1 without the demulsifier, and the membrane blockage was suppressed by adding the demulsifier.

(Example 3)
For the same ultrafiltration membrane concentrate (about 15 times, volume ratio) as in Example 1, after heating the concentrate to 30 ° C., the water-soluble demulsifier (Emulsion Breaker # 3500 manufactured by Matsuken Co., Ltd.) was used. The mixture was added and mixed at a rate of 1000 mg per kg of the concentrated liquid, introduced into a centrifuge, and separated into three phases of water, oil and solid.

As shown in Table 4, the water content of the recovered oil after centrifugation of the concentrate was 0.95%, the calorific value was 39.9 MJ / kg, and the calorific value was almost the same as that of heavy oil. Further, since the demulsifier is water-soluble, and almost all of the demulsifier is contained in the oil-containing water generated in the centrifugation step, it is estimated that the demulsifier is dissolved in 800 mg / L in the oil-containing water. It was.
Next, the oil-containing water was added to and mixed with the concentrated liquid at a rate of 1000 mg per kg of the concentrated liquid, and this was introduced into a centrifuge to separate into three phases of water, oil, and solid.

  The recovered oil after centrifugation of the concentrate had a water content of 0.92% and a calorific value of 39.5 MJ / kg. Similar to Example 1, the heat generated by the centrifugally recovered oil was almost the same as that of heavy oil. From Table 5, it was possible to reuse the demulsifier in the oil-containing water generated in the centrifugation step.

(Comparative Example 1)
The same demulsifier as in Example 1 is added to and mixed with the test raw water as in Example 1 at a rate of 1000 mg per kg of the raw water, and this is introduced into a centrifuge and mixed with water, oil and solid matter. Separated into three phases.

  As shown in Table 6, the normal hexane extract substance concentration of the water (treated water) obtained in the centrifugation step is 850 mg / L, and secondary treatment such as biological treatment is required to discharge it into the sewer as it is. Met. On the other hand, the water content of the recovered oil after the centrifugation treatment was 0.99%, and the calorific value was 39.8 MJ / kg. The calorific value of the centrifugally recovered oil was almost the same as that of heavy oil.

DESCRIPTION OF SYMBOLS 1 ... Raw water tank 2 ... Membrane filtration processing means 3 ... Heater 4 ... Centrifugal separator 5 ... Pressure pump 11 ... Steam piping 21 ... Return piping 31 ... Circulation piping 41 ... Return piping

Claims (5)

A method for treating cutting fluid waste liquid,
A membrane filtration separation step for separating into high-concentration oil content in the cutting fluid waste liquid and water not containing oil content by membrane filtration treatment;
A centrifugal separation step of separating the oil component of high concentration by centrifuging the oil component, water and solids;
And a demulsifier addition step of adding a demulsifier prior to the membrane filtration separation step or the centrifugal separation step.   It has a heating step of heating the cutting oil waste liquid to 30 ° C. to 65 ° C. at the time of addition of the demulsifier in the demulsifier addition step, or before or after the addition. The processing method of the cutting oil waste liquid of Claim 1.   The processing method of the cutting oil waste liquid according to claim 1 or 2, wherein the cutting oil waste liquid contains a water-soluble cutting oil.   The processing method of the cutting oil waste liquid according to any one of claims 1 to 3, wherein the demulsifier is water-soluble. A heating means for heating the cutting oil waste liquid;
Membrane filtration treatment means for introducing cutting oil waste liquid before or after heating by the heating means, and separating into high concentration oil content and water not containing oil content in the cutting oil waste liquid by membrane filtration treatment; ,
A return means for returning the high-concentration oil to the heating means;
Centrifugation means for separating the cutting oil waste liquid after heating by the heating means and separating it into oil, water and solids by centrifugation,
An apparatus for treating a cutting oil waste liquid, comprising: a demulsifier adding means for adding a demulsifier to a cutting oil waste liquid before or after the heating means.