JP5291418B2 - Method for recovering volatile organic compounds - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recovery method for easily and safely recovering a volatile organic compound from waste including the volatile organic compound, and also to provide a recovery apparatus therefor. <P>SOLUTION: In the recovery method of the volatile organic compound, a container containing a volatile organic compound solution which is one of the mixture of the plurality of volatile organic compounds, the mixture of the volatile organic compound and a resin, and the mixture of the plurality of volatile organic compounds and the resin is heated by induction heating. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a recovery method for recovering a volatile organic compound easily and safely.

Volatile organic compounds such as toluene, benzene, xylene, and N, N-dimethylformamide are used in various solvents as solvents for dissolving resins and diluting solutions for dilution.
Conventionally, a residue of a resin solution or a diluted solution using a volatile organic compound after being used for industrial production has been incinerated as waste. However, waste containing such volatile organic compounds is required to be treated by a treatment method other than incineration from the viewpoint of volume reduction of waste and effective use of resources.
Therefore, a method for separating and recovering waste containing a plurality of volatile organic compounds by distillation using the difference in boiling points of the volatile organic compounds has been studied.

In such a method for recovering a volatile organic solvent by distillation, as a means for heating waste containing a volatile organic compound, a method using a gas burner, an electric heater or the like, an indirect heat treatment using steam, etc. are studied. ing.
Moreover, although the object to be heated is moisture, there is a method of separating moisture and other components by selectively evaporating moisture by dielectric heating using a microwave (see Patent Document 1).
JP-A-6-226246

However, when a gas burner or an electric heater that heats at a high temperature is used as a heating means during distillation, the volatile organic compound leaking from the container may explode. In order to prevent the explosion, a sealed container and a device with safety measures such as filling the container with an inert gas can be used. However, the device itself becomes expensive. Gas burners and electric heaters also have a problem that energy efficiency is poor when recovering volatile organic compounds. If an explosion-proof electric heater is used, the possibility of explosion can be avoided, but the energy efficiency at the time of recovery of the volatile organic compound becomes worse.
Furthermore, in the case of performing indirect heat treatment using water vapor, there are problems that it takes time to heat the waste containing the volatile organic compound and that temperature control is difficult.

Moreover, although it is possible to heat and isolate | separate a volatile organic solvent instead of a water | moisture content by the method of the cited reference 1, there exists a possibility of bumping. Furthermore, it is difficult to control a resin solution having a high viscosity and a mixture of a plurality of volatile organic compounds to a specific temperature by this method in which only moisture is separated, and separation of the volatile organic compounds is difficult.
In addition, when microwaves are used, it is necessary to use a container such as ceramics that does not generate sparks, and the microwaves are prevented from leaking to the outside, and the microwaves are efficiently irradiated. Therefore, there is a problem in that the apparatus itself is considerably expensive.

  This invention is made | formed in view of the said situation, and it aims at providing the collection | recovery method and its collection | recovery apparatus which collect | recover a volatile organic compound easily and safely from the waste containing a volatile organic compound.

In order to achieve the above-described problems, the present invention employs the following configuration.
Volatilization in which the bottom and side surfaces of a container in which a volatile organic compound solution that is one of a mixture of a volatile organic compound and a resin and a mixture of a plurality of volatile organic compounds and a resin is placed are heated by induction heating. In this method, the heat treatment temperature on the side surface is lower than the heat treatment temperature on the bottom surface.

According to the method for recovering a volatile organic compound of the present invention, the volatile organic compound is easily and safely recovered from the waste containing the volatile organic compound (“volatile organic compound solution” described in [1]). be able to. Further, the volatile organic compound recovered by the recovery method of the present invention can be reused as a solvent, a diluent, or a fuel.
By using the volatile organic compound recovery apparatus of the present invention, it is possible to recover volatile organic compounds easily and safely from waste containing the volatile organic compounds (the volatile organic compound solution described in [1]). it can. In addition, the volatile organic compound recovered using the recovery device of the present invention can be reused as a solvent, a diluent, or a fuel.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this embodiment is for demonstrating the summary of this invention, and does not limit this invention unless there is particular limitation.

<Volatile organic compound recovery device>
The schematic diagram of one Embodiment of the volatile organic compound collection | recovery apparatus of this invention is shown in FIG. As shown in FIG. 1, the volatile organic compound recovery apparatus 10 of the present invention includes a mixture of a plurality of volatile organic compounds, a mixture of a volatile organic compound and a resin, and a plurality of volatile organic compounds and a resin. It has the container 11 in which the induction heating for putting the volatile organic compound solution 21 which is either of the mixtures, the induction heating means 12a, and the induction heating means 12b.

(container)
As the container 11, a cylindrical drum can having a capacity of 200 L and a heat resistant temperature of 900 ° C. manufactured using a steel material capable of induction heating is used.
In addition, the material of the container 11 should just be what can be induction-heated, and the material containing a metal and / or a magnetic material is mentioned.
Specific examples include aluminum, tin, lead, zinc, copper, nickel, molybdenum, titanium, magnesium, manganese, chromium, silver, iron, platinum, and alloys such as steel, stainless steel, and nichrome. Carbon can also be heated by induction heating.
In particular, those containing iron and nickel are preferable from the viewpoint of heating efficiency because they have excellent exothermic properties due to eddy current and hysteresis loss during induction heating.
Among these, from the viewpoint of workability and economy, it is preferable to use an alloy containing iron as a main component, and specifically, steel is preferable. Here, iron as a main component means that 50 to 100% by mass of iron in the total amount of the alloy is contained.

  Moreover, the heat-resistant temperature of the container 11 should just be 500 degreeC or more from a viewpoint of collection | recovery of a volatile organic compound, and if it carries out to carbonization of the residue of a volatile organic compound solution especially, it should be 800 degreeC or more. Is more preferable, and more preferably 1500 ° C. or higher. There is no upper limit to the heat-resistant temperature of the container.

In addition, the shape of the container 11 is preferably cylindrical from the viewpoint that uniform heating by induction heating is possible.
In addition, what is a polygonal columnar body, such as a rectangular parallelepiped and a cube, is also used as the container 11.
Specific examples of cylindrical containers include drums manufactured using steel materials.
Drums are used to transport and store resins and volatile organic compounds. Also, when additives are added to resins and volatile organic compounds to form processing solutions, they are generally used as processing solutions by pouring them into processing baths after mixing and mixing in drums. .
Therefore, if a drum can is used as a container for induction heating, it is necessary to transfer the volatile organic compound solution remaining in the drum can after the resin processing or the like at the office to another container. In addition, the loss of volatile organic compound resin and the loss of time that occur at the time of transfer can be reduced. In addition, the processing solution remaining in the processing bath can be returned to the original drum can for induction heating, so that it is not necessary to prepare a special container, and the apparatus is inexpensive and preferable.
Further, the capacity of the container 11 is not particularly limited. However, it is preferable that a general drum can having a capacity of 20 to 200 L is used because the apparatus is inexpensive.

Further, as shown in FIG. 1, a heat insulating material 15 is installed on the side surface of the container 11. By performing the heat insulation treatment with the heat insulating material 15, it is possible to prevent the release of heat from the container during induction heating.
The heat insulating material 15 may or may not be installed. Furthermore, when the heat insulating material 15 is installed, the heat insulating material may be installed not only on the side surface of the container 11 but also on the bottom surface.
As a heat insulating material, a calcium silicate foam, a mineral type thing, glass wool, etc. can be used.

Further, as shown in FIG. 1, the container 11 is provided with thermometers 16a to 16c for measuring the temperature of the side, bottom and inside of the container for the purpose of temperature control in the container.
The thermometer 16a to the thermometer 16c may be anything as long as the temperature can be measured, and a pin-shaped temperature sensor like the thermometer 16c can be used in addition to a general thermometer and a temperature sensor.
In addition, the installation location of the thermometer is not limited to the side surface, the bottom surface, and the inside of the container, and may be installed in a location where temperature control for recovering the volatile organic compound can be performed. Moreover, the installation location of the thermometer when measuring the temperature of the side surface and the bottom surface of the container may be either the inner surface or the outer surface of the container.
Moreover, the opening part of the container 11 is closed with the lid | cover 17, and piping which penetrates this is attached to this lid | cover 17. As shown in FIG.

(Induction heating means)
The induction heating means in the volatile organic compound recovery apparatus of the present invention is a heating means using electromagnetic induction.
As shown in FIG. 1, the induction heating means 12a and the induction heating means 12b are composed of a high frequency generator (power source) 13a and a high frequency generator (power source) 13b for causing electromagnetic induction, an induction coil 14a, and an induction coil 14b. It is configured.

An AC power source is used as the high frequency generator (power source).
A conductor is used as the material of the induction coil. Specific examples of the conductor include aluminum, tin, lead, zinc, copper, nickel, molybdenum, titanium, magnesium, manganese, chromium, silver, iron, platinum, and alloys thereof. Among these, copper is preferable because it is relatively inexpensive, has low electrical resistance, and generates little heat from the coil itself.

In addition, the cross-sectional shape of the strand which comprises an induction coil may be a hollow multiplex structure. Specifically, an induction coil 50 having a hollow double structure having an outer layer 53 made of an insulator, an inner layer 52 made of a conductor, and a hollow portion 51 shown in FIG.
Examples of the insulator provided from the viewpoint of preventing electric shock include ceramics, resins, and rubbers.
The hollow portion 51 is a passage for a coolant such as water. This is to prevent the induction coil from rising in temperature due to heat dissipation from the container 11 during induction heating, electrical resistance when a current is passed through the induction coil, and the like.

As shown in FIG. 1, the induction coil 14 a and the induction coil 14 b are attached to the positions of the side surface and the bottom surface of the container 11. In the volatile organic compound recovery device of the present invention, it is preferable that the heating area by the induction heating means for the container is large, and the heating area may be increased by heating the side and bottom surfaces of the container.
As shown in FIG. 1, when the induction coil 14 b is installed under the bottom surface of the container 11, the bottom surface of the container 11 can be heated. Furthermore, by arranging the container 11 in the induction coil 14a wound in a cylindrical shape, the induction coil 14a is installed on the side surface of the container 11, and the side surface of the container 11 can be heated.
Thus, when the induction coil 14a and the induction coil 14b are installed, even if the viscosity of the volatile organic compound solution is high, convection of the volatile organic compound solution is promoted, and the resin contained in the volatile organic compound solution It can suppress that non-volatile components, such as, burn to a container.
In addition, the installation position of the induction coil is not limited to the side surface and the bottom surface of the container 11 and may be either one.

In addition, the distance from the induction coil 14a and the induction coil 14b (the position closest to the outer surface of the induction coil container) to the container 11 (the outer surface of the container closest to the induction coil) shown in FIG. 1 is 7 cm.
The distance from the induction coil (the place closest to the outer surface of the induction coil container) to the container (the outer surface of the container closest to the induction coil) is preferably 1 to 30 cm, and more preferably 3 to 15 cm.
When the distance is less than 1 cm, it is not preferable from the viewpoint of workability and safety, and when it exceeds 30 cm, it is difficult to sufficiently heat the container, and energy efficiency may be reduced.

When such an induction heating means having a high-frequency generator (power source) and an induction coil is used, the induction heating means itself does not reach a high temperature during heating, unlike a flame using gas or an electric heater. Therefore, a heating element having a temperature higher than that of the heated container does not exist around the volatile organic compound solution, and there is no fear of explosion and the safety is excellent.
In addition, when such an induction heating means is used, the temperature in the container can be controlled by adjusting the output of the high-frequency generator (power supply), and the temperature control is easy.

(Cooling means)
The volatile organic compound recovery apparatus 10 shown in FIG. 1 is provided with a cooling means 18 for cooling the volatilized volatile organic compound and returning it to a liquid.
Examples of the cooling means 18 include an air-cooled type, a water-cooled type using water, a cooling device such as a heat exchanger using a refrigerant other than water, and a natural cooling device using outside air temperature.

The cooling means 18 is provided with a pipe for collecting the volatile organic compound 19 returned to the liquid, and a collection container for collecting the volatile organic compound 19 is installed at the end of the pipe.
In particular, when individually recovering a plurality of volatile organic compounds, like the volatile organic compound recovery device 30 shown in FIG. 2, the cooling is first performed via a branched pipe 32 installed in the cooling means 18. It is preferable that a recovery container 33 to a recovery container 35 for recovering the volatile organic compound formed are installed. In addition, between the cooling device 18 and the collection container 33 to the collection container 35, a valve 36 to a valve 38 whose opening / closing switching is adjusted by the temperature of the outer surface of the container at the time of induction heating are installed.
The temperature measurement location for switching between opening and closing of the valves 36 to 38 is not limited to the outer surface temperature of the container 11, and may be the temperature in the container or the temperature of the volatile organic compound solution in the container. Any place where the temperature at which the cooled volatile organic compound can be divided into the recovery container 33 to the recovery container 35 can be measured may be used.

  In addition, piping for discharging the gas 20 that has not been liquefied by the cooling means 18 is also installed in the cooling means 18 shown in FIG. A suction means for sucking the generated gas, a deodorizing device, or the like may be installed at the end of the pipe.

(Superheated steam supply means)
Further, the volatile organic compound recovery device 10 of the present invention uses superheated steam for performing carbonization treatment on the residue after the volatile organic compound is recovered from the volatile organic compound solution 21 in the container 11. Supply means may be installed. The superheated steam supply means is for supplying superheated steam into the container, and a pipe (pipe) having a hole or a nozzle is used.
The superheated steam supply means may be attached to the lid, side surface, bottom surface or the like of the container, and is preferably installed so that the superheated steam can be effectively blown into the container, particularly the residue. From the viewpoint of reuse and handling of the container, a pipe having a large number of holes for supplying superheated steam to the container lid 17 may be installed as the superheated steam supply means.
The superheated steam supply means may be installed in the volatile organic compound recovery device 10 after recovering the volatile organic compound. Specifically, a lid in which a pipe having a large number of holes for supplying superheated steam into the container is installed as the superheated steam supply means is prepared separately from the lid 17 used at the time of recovering the volatile organic compound. Preferably it is. And after a volatile organic compound is collect | recovered, a superheated steam supply means is good to be installed in the volatile organic compound collection | recovery apparatus 10 by attaching the lid | cover in which the superheated steam supply means was installed in the container 11. FIG.
If the residue does not contain flammable, ignitable and explosive volatile organic compounds, a gas burner or an electric heater may be installed as a means for performing carbonization.

<Recovery method of volatile organic compounds>
Next, a method for recovering the volatile organic compound will be described.
The volatile organic compound recovery method of the present invention is a volatile organic compound, a mixture of a plurality of volatile organic compounds, a mixture of a volatile organic compound and a resin, and a mixture of a plurality of volatile organic compounds and a resin. This is a volatile organic compound recovery method in which a container containing an organic compound solution is heat-treated by induction heating, and is preferably performed using a volatile organic compound recovery apparatus as shown in FIG.
Hereinafter, the volatile organic compound recovery method of the present invention will be described with reference to FIG. 1 which is a schematic diagram of an embodiment of the volatile organic compound recovery device of the present invention. However, the recovery method of the present invention is limited to this. Is not to be done.

(Volatile organic compound solution)
Examples of volatile organic compounds include acetone, methanol, ethanol, isopropyl alcohol, isobutyl alcohol, propylene glycol monoethyl ether (hereinafter referred to as “MPG”), ethyl acetate, methyl ethyl ketone (hereinafter referred to as “MEK”), and the like. Examples include benzene, toluene (hereinafter referred to as “TOL”), xylene, N, N-dimethylformamide (hereinafter referred to as “DMF”), and the like, which are generally classified as volatile organic compounds (VOC). . Further, it may be a mineral spirit.

  The volatile organic compound solution 21 placed in the container 11 is a mixture containing two or more of the above volatile organic compounds, or a mixture of one or more of the above volatile organic compounds and a resin. .

Examples of the mixture containing two or more volatile organic compounds include a mixture of MEK, TOL, and DMF, a mixture of MPG, DMF, and the like. However, it is not limited to these combinations.
When two or more kinds of volatile organic compounds are contained, a mixture of volatile organic compounds having different boiling points is preferable because the recovered volatile organic compounds are easily separated for each volatile organic compound.

Moreover, as resin which the volatile organic compound solution 21 contains, a urethane resin, an acrylic resin, a silicone resin, a polycarbonate resin, a vinyl acetate resin, a fluororesin, etc. can be mentioned, These 1 type (s) or 2 or more types are used. be able to.
As a mixture of one or more of the above volatile organic compounds and a resin, a mixture of urethane resin and DMF, a mixture of urethane resin, MEK, and TOL, a mixture of urethane resin, MEK, TOL, and DMF, Examples thereof include a mixture containing a fluorine-modified acrylic resin, acetone, mineral spirit, and the like used for water repellents. However, it is not limited to these combinations.

  In addition to volatile organic compounds and resins, the volatile organic compound solution 21 is added to resins such as pigments, crosslinking agents, antioxidants, ultraviolet absorbers, plasticizers, penetrants, organic fine particles, inorganic fine particles, and antibacterial agents. Various additives may be added.

In the volatile organic compound recovery method of the present invention, the viscosity (20 ° C.) of the volatile organic compound solution 21 is preferably 100000 mPa · s or less. The lower limit is not particularly limited, and there is no problem as long as the viscosity is low.
When the viscosity (20 ° C.) of the volatile organic compound solution 21 exceeds 100000 mPa · s, the convection of the volatile organic compound solution 21 in the container 11 is deteriorated when the heat treatment is performed by induction heating, and the side surface of the container is burnt. May occur.
Moreover, even if the viscosity (20 degreeC) before heat processing exceeds 100000 mPa * s, if fluidity comes out by heat processing, as the volatile organic compound solution 21 in this invention, Can be used.

(Induction heating)
In the volatile organic compound recovery method using the volatile organic compound recovery apparatus 10, the container 11 containing the volatile organic compound solution 21 as described above is induction-heated by the induction heating means 12a and the induction heating means 12b. .
Specifically, a current having a constant frequency is supplied from the high-frequency generator (power source) 13a and the high-frequency generator (power source) 13b to generate an electromagnetic field in the induction coil 14a and the induction coil 14b. Since the container 11 is installed in this electromagnetic field, an induced current is generated in the container 11 and only the container 11 is heated. This is induction heating. Then, the heated container 11 heats the volatile organic compound solution 21 in the container 11. In addition, if the electric current currently supplied from the high frequency generator (power supply) 13a and the high frequency generator (power supply) 13b is cut | disconnected, an electromagnetic field will lose | disappear and the heating of the container 11 will stop. The temperature of the container 11 is adjusted by the heating time by induction heating or the power during induction heating, and the heating temperature of the volatile organic compound solution 21 can be adjusted. The temperature of the container 11 is measured by thermometers 16a to 16c attached to the container 11. Thus, since the temperature of the container 11 can be adjusted while confirming temperature with the thermometer 16a-the thermometer 16c, it is set as the heating temperature according to each boiling point of the volatile organic compound solution 21 in the volatile organic compound solution 21. It is possible to individually collect the volatile organic compounds in the volatile organic compound solution.

  At this time, the frequency of the current in the high-frequency generator (power source) 13a and the high-frequency generator (power source) 13b depends on the material and thickness of the container containing the volatile organic compound solution, the distance between the container and the induction coil, and the shape of the induction coil. Although it depends on the material and size (thickness) of the induction coil, it is preferably 1 kHz to 100 kHz, more preferably 3 kHz to 30 kHz, from the viewpoint of heating efficiency. Depending on this frequency, the depth of heat penetrating in the thickness direction of the vessel to be induction-heated differs. Therefore, when the frequency is less than 1 kHz, the container may be dissolved. Further, when the frequency exceeds 100 kHz, the container surface is heated in a concentrated manner, so that the heating efficiency tends to decrease.

  Moreover, it is preferable that the electric power in the high frequency generator (power supply) 13a and the high frequency generator (power supply) 13b at this time is 0.1-50 kW, and it is more preferable that it is 1-20 kW. When the electric power exceeds 50 kW, the container is rapidly heated, heated more than the heat conduction to the volatile organic compound solution, and may exceed the heat resistance temperature of the container. On the other hand, in the case of less than 0.1 kW, there is a large heat dissipation loss and the heating efficiency tends to be lower than the heat conduction to the internal volatile organic compound solution.

The heat treatment temperature during induction heating depends on the type of the volatile organic compound, but it may be about 60 to 500 ° C. at the temperature of the container 11 (the temperature of the outer surface of the side surface of the container heated by induction heating). Depending on the boiling point of the target volatile organic compound, it is preferable to perform heat treatment in a plurality of stages at a plurality of temperatures.
The heat treatment time during induction heating is preferably about 30 to 720 minutes in the case of a volatile organic compound solution of about 100 kg, although it depends on the amount of the volatile organic compound solution.

For example, when a 100 L volatile organic compound solution containing MEK, TOL, and DMF is used as the volatile organic compound, it is heated at room temperature (about 20 ° C.) to 120 ° C. for 1 to 120 minutes at the outer surface temperature of the container. By processing, MEK is mainly recovered. Subsequently, TOL is mainly recovered by heat treatment at 121 to 140 ° C. for 1 to 120 minutes. Subsequently, DMF is mainly recovered by heat treatment at 141 to 160 ° C. for 1 to 180 minutes.
The temperature measurement location is not limited to the outer surface temperature on the side of the container, and may be the temperature in the container or the temperature of the volatile organic compound solution in the container. The temperature is not particularly limited as long as it is a temperature at a location where collection can be managed.

In order to accelerate the heat treatment of the volatile organic compound solution in the container, the heat treatment area by induction heating on the container may be increased. Specifically, as shown in FIG. 1, not only the heating of the bottom surface of the container using the induction coil 14b but also the heating of the side surface of the container using the induction coil 14a may be performed. When side heating is also performed, convection of the volatile organic compound solution is promoted.
In particular, when the volatile organic compound solution 21 in the container 11 contains a resin and the viscosity of the volatile organic compound solution is high, the convection of the volatile organic compound solution is increased by increasing the heat treatment area in this way. Since it is promoted and the heating amount per unit area can be reduced, it is possible to prevent the resin from being burnt to the container.
Further, the heat treatment temperatures of the side surface and the bottom surface by the induction heating unit 12a and the induction heating unit 12b may be the same temperature or different temperatures. From the viewpoint of suppressing the burning of the resin to the container, the container More preferably, the temperature of the side surface of the container is lower than the temperature of the bottom surface, and the side surface and the bottom surface of the container are heated by induction heating.
In addition, when the volatile organic compound solution in a container does not convect, the volatile organic compound collect | recovered by the phenomenon of the burning of resin occurring during collection | recovery of a volatile organic compound may be colored brown, and is unpreferable.

(Cooling, recovery)
The vaporized volatile organic compound that has been heat-treated by induction heating by the induction heating unit 12a and the induction heating unit 12b is cooled and condensed using the cooling unit 18, and is collected in a collection container through a pipe installed in the cooling unit 18. The The cooling temperature is not particularly limited as long as it is not higher than the temperature at which the target volatile organic compound can be liquefied.
At this time, as shown in FIG. 2, if the pipe 32 having a branch installed in the cooling means 18 is attached with a valve 36 to a valve 38 that can be switched according to the heating temperature of the container 11, The volatile organic compound can be separately collected in the collection container 33 to the collection container 35 according to the boiling point of the volatile organic compound.
Further, when the recovered volatile organic compound is heat-treated again by induction heating, a volatile organic compound with higher purity is recovered. When the recovered volatile organic compound is heat-treated again, it is preferable to use a container capable of induction heating as the first collection container because the heat treatment by induction heating can be performed without replacing the container.

(Heat treatment, carbonization treatment)
From the viewpoint of reducing the volume of waste, it is preferable to further heat-treat the residue after recovering the volatile organic compound from the volatile organic compound solution.
Furthermore, if the residue after the recovery of volatile organic compounds in the container is carbonized, the residue can be reused as a fuel, adsorbent, or deodorant, and effective use of resources can be achieved. It is more preferable because it is possible.
For such heat treatment and carbonization treatment, induction heating or heating with superheated steam can be used. Among them, it is more preferable to perform a carbonization treatment with superheated steam because the amount of heat is large and a reducing atmosphere can be created and the residue is carbonized to easily obtain charcoal having adsorption performance, deodorization performance, and the like. The superheated steam used for the carbonization treatment is preferably 120 ° C. to 1500 ° C., and the temperature of the superheated steam is more preferably 700 ° C. or more from the viewpoint of the adsorptivity and deodorizing properties of the carbonized residue.
Note that a gas burner, an electric heater, or the like may be used during the carbonization treatment so long as flammable, ignitable, and explosive volatile organic compounds do not remain in the residue.

The carbonization treatment with superheated steam is preferably performed at 500 to 1500 ° C. (in-container temperature) for about 30 to 720 minutes. When heat treatment is performed under such conditions, it is possible to carbonize the residual resin or the like that is a residue.
In addition, from the viewpoint of imparting deodorant performance and the like to the residue, it is more preferable that the heat treatment temperature with superheated steam is 700 ° C. or higher (container temperature, preferably reducing atmosphere).
In addition, from the viewpoint of carbonization stability, it is particularly preferable to heat-treat the container by induction heating or the like in addition to the process of directly contacting superheated steam with the residue. Specifically, it is more preferable from the viewpoints of safety and workability that the superheated steam and the residue are directly brought into contact with each other while the container is heated by induction heating to perform carbonization.
In addition, it is preferable from the viewpoint of energy efficiency during carbonization that the volatile organic compound in the residue is sufficiently volatilized and removed by heat treatment such as induction heating before carbonizing the residue with superheated steam. .

By using the volatile organic compound recovery apparatus and recovery method as described above, when recovering the volatile organic compound from the volatile organic compound solution, there is no risk of explosion or the like and it is safe. Moreover, temperature control when recovering the volatile organic compound from the volatile organic compound solution is easy, and the volatile organic compound can be efficiently separated and recovered. Furthermore, since it is not necessary to prepare a special container or apparatus when recovering the volatile organic compound from the volatile organic compound solution, the volatile organic compound recovery apparatus can be provided at low cost.
The volatile organic compound recovered by the volatile organic compound recovery device and recovery method can be effectively used as a fuel for solvents, diluents, boilers, etc., and discharges volatile organic compounds to the environment. Control and reduce the amount of waste.
In addition, the residue remaining in the container after the recovery of the volatile organic compound can be carbonized in the container to reduce (reduce) the waste, and further, the residue (carbon ) Can also be used for other applications such as fuel, adsorbent, deodorant, etc., and is preferable from the environmental viewpoint.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
The following examples will be described using the schematic diagram of an example of the volatile organic compound recovery apparatus of the present invention shown in FIG.

<Example 1>
In the volatile organic compound recovery apparatus 30 of FIG. 2 used in the example of the present invention, a 200 L drum can (heat resistant temperature 900 ° C.) manufactured using a steel plate was used as the container 11 into which the volatile organic compound solution was placed. . The side surface of the container 11 was covered with a heat insulating material 15.

The volatile organic compound recovery device 30 includes an induction heating means 12b composed of a high frequency generator (power source) (HI HEATER 4020N, manufactured by Daiichi RF Co., Ltd.) 13b and an induction coil 14b, and a high frequency generator (power source) 13a. And an induction heating means 12a comprising the induction coil 14a.
The spiral induction coil 14 b was installed under the container 11. Furthermore, the container 11 was installed in the induction coil 14 a (inside the cylindrical shape formed by the coil), and the induction coil 14 a for induction heating was installed around the side surface of the container 11. Here, the number of turns of the induction coil 14a was 13. The distance between the induction coil 14a and the induction coil 14b and the container 11 was 7 cm.
The induction coil 14a and the induction coil 14b are shown in FIG. 3, in which the wire has a hollow double structure, and the inner layer 52 made of copper is covered with the outer layer 53 made of an insulating resin tube. A coil 50 was used. Further, water was passed through the hollow portion 51 of the induction coil so that the temperature of the coil did not rise during heating by induction heating.

  A thermometer 16a and a thermometer 16b were attached to the outer surface of the side surface and the bottom surface of the container 11, respectively, so that the temperature of the side surface (outer surface) of the container and the temperature of the bottom surface (outer surface) of the container could be measured. In addition, a thermometer 16c is also attached to the lid 17 of the container so that the temperature inside the container 11 can be measured.

  Further, a pipe 31 for allowing the vaporized volatile organic compound to pass through was installed on the lid 17 of the container 11, and the pipe 31 and the cooling means 18 were connected. A water-cooled heat exchanger was used as the cooling means 18.

The cooling means 18 is provided with a pipe 32 for passing a volatile organic compound that has been cooled and liquefied, and a pipe 39 for releasing a gas that has not been liquefied by the cooling means 18. Further, a MEK recovery container 33, a TOL recovery container 34, and a DMF recovery container 35, which can recover a cooled and liquefied volatile organic compound, were installed at the tip of the pipe 32, respectively.
Further, between the cooling means 18 and the collection container 33 to the collection container 35, a valve 36 to a valve 38 that are controlled to be opened and closed by the temperature of the side surface (outer surface) of the container are attached. Here, electromagnetic valves were used as the valves 36 to 38. The temperature at which the MEK valve 36 opens (the temperature on the side of the container (outer surface)): room temperature (20 ° C.) to 120 ° C. The temperature at which the electromagnetic valve 37 for the TOL opens (temperature on the side of the container (outer surface)): The temperature was set to 121 to 140 ° C., and the temperature at which the DMF solenoid valve 38 was opened (temperature of the container side surface (outer surface)) was set to 141 to 160 ° C.

Moreover, the deodorizing device 40 was attached to the tip of the pipe 39 for releasing the gas that was not liquefied by the cooler. The deodorizing device 40 was provided with an exhaust port 41 and a drain 42.
Although not shown, a suction means for sucking the gas generated from the container was installed between the deodorizing device 40 and the cooling means 18.

Next, the volatile organic compound was recovered from the volatile organic compound solution by the following procedure.
As the volatile organic compound solution, a mixture of the following components was used.
(Volatile organic compound solution)
Viscosity 2000 mPa · s (20 ° C.), waste resin generated during synthetic leather production, 150 kg.
Urethane resin 29 parts by weight White pigment 6 parts by weight MEK 45 parts by weight TOL 10 parts by weight DMF 60 parts by weight

The container 11 containing the volatile organic compound solution 21 (150 kg) was heat-treated by induction heating. The frequency used for induction heating was 12 kHz (constant).
Since the volatile organic compounds contained in the volatile organic compound solution are MEK, TOL, and DMF, first, in order to recover MEK, the container 11 is heated by induction heating, and the container side surface temperature (outer surface) is set to room temperature (outside surface). The temperature was raised from 120 ° C. to 120 ° C. over 120 minutes.
Subsequently, in order to recover TOL, the container 11 was heated by induction heating, and the container side surface temperature (outer surface) was raised to 140 ° C. over 60 minutes.
Furthermore, in order to collect | recover DMF, the container 11 was heated by induction heating and the container side surface temperature (outer surface) was heated up to 160 degreeC over 60 minutes.
The temperature of the bottom surface of the container 11 was always 300 ° C. (outer surface) from the time of collection.

Through the above-described operation, colorless and transparent MEK, TOL, and DMF were collected in the collection containers 33 to 35 of MEK, TOL, and DMF.
The recovered volatile organic compound could be used as a solvent for a urethane resin solution for producing synthetic leather.

Next, in place of the lid 17, a lid connected to a pipe for blowing superheated steam into the container 11 was attached to the container 11 in addition to the thermometer 16 c and the pipe 31.
By injecting superheated steam (800 ° C.) into the container 11 and simultaneously performing heating by induction heating and heating by superheated steam, the carbonization treatment of the residue 25 kg of the volatile organic compound solution is made to 800 ° C. (temperature in the container). For 3 hours.
The obtained carbide was 5 kg, and the volume of waste was reduced. Moreover, when the deodorizing performance was confirmed by the following deodorizing tests with the obtained carbide, the deodorizing performance was confirmed.

(Deodorization test)
The deodorization test was performed according to the following procedure.
First, 1.0 g of the obtained carbide was added to a 500 ml Erlenmeyer flask. Next, 2 μl of MEK was injected into the Erlenmeyer flask, and the Erlenmeyer flask was covered with a film, sealed, and shaken lightly. After this Erlenmeyer flask was allowed to stand at 25 ° C. for 16 hours, 1 ml of air in the Erlenmeyer flask was sampled, and the MEK concentration was measured using a gachromatograph to obtain the MEK concentration (X) when carbide was added. .
Further, except that no carbide was added to the Erlenmeyer flask, the concentration of MEK in the Erlenmeyer flask was measured in the same manner as the MEK concentration (Y) when no carbide was added.
The MEK concentration (X) when carbide was added was 11 ppm, and the MEK concentration (Y) when carbide was not added was 876 ppm. Therefore, the deodorization rate of carbide MEK obtained from the following general formula (1) was 99%, and the deodorization property was confirmed.
(MEK concentration (Y) −MEK concentration (X)) / MEK concentration (Y) × 100 = deodorization rate of carbide MEK (1)

As described above, when the volatile organic compound is recovered from the volatile organic compound solution generated after the production of the synthetic leather using the recovery method and the recovery apparatus of the present invention, the volatile organic compound (MEK, TOL) is easily and safely recovered. , DMF) was recovered, and the recovered MEK, TOL, and DMF could be used again as a solvent for the resin solution for synthetic leather production.
Therefore, according to the method and apparatus for recovering volatile organic compounds of the present invention, useful volatile organic compounds can be obtained from volatile organic compound solutions that have been discarded as waste, and effective use of resources. Can be said. Further, it is possible to suppress the release of volatile organic compounds to the outside environment such as the atmosphere or water system, and to reduce the burden on the environment.
Furthermore, if it carries out to carbonization process, the solid content contained in the volatile organic compound solution can be utilized more effectively.

It is a schematic diagram of one Embodiment of the volatile organic compound collection | recovery apparatus of this invention. 1 is a schematic diagram of a volatile organic compound recovery device of the present invention used in Example 1. FIG. 1 is a perspective view of an induction coil used in Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 30: Volatile organic compound collection | recovery apparatus 11: Container 12a, 12b: Induction heating means 13a, 13b: High frequency generator Induction coil: 14a, 14b, 50
Outer layer: 53, inner layer: 52, hollow part: 51

Claims (1)

Volatilization in which the bottom and side surfaces of a container in which a volatile organic compound solution that is one of a mixture of a volatile organic compound and a resin and a mixture of a plurality of volatile organic compounds and a resin is placed are heated by induction heating. A method for recovering an organic compound,
A method for recovering a volatile organic compound, wherein the heat treatment temperature on the side surface is lower than the heat treatment temperature on the bottom surface .

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