JP2012183462A - Method and apparatus for removal of organic solvent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for removal of low-boiling-point organic solvents which is packed with active carbon fiber (ACF), has improved efficiency of removing organic solvents from exhaust gas, allows ACF to exert its maximum adsorption capacity in order to reduce running costs and apparatus manufacturing costs.SOLUTION: The apparatus for removal of organic solvents includes the first adsorption vessel A packed with ACF6, the second adsorption vessel B packed with ACF 26 identical to or different from the ACF6 in a mass ratio M/Mof 0.05-0.25, where Mis the mass of ACF packed in the first adsorption vessel and Mis the mass of ACF packed in the second adsorption vessel, a connection pipe 24 connecting the first adsorption vessel A to the second adsorption vessel B, a condenser 25 connected through the connection pipe 24 and steam injection means 15 and 35 arranged, respectively, in the first adsorption vessel A and the second adsorption vessel B.

Description

  The present invention relates to a method and an apparatus for removing an organic solvent, which efficiently and inexpensively separates and removes a solvent from a low-flow target gas containing a high-concentration organic solvent discharged from a factory or the like.

  Exhaust gas containing organic solvents with relatively low boiling points such as methylene chloride and trichlorethylene contained in exhaust gas from cleaning equipment and film coater equipment at electronic equipment manufacturing factories, metal processing factories, etc. Since the release causes environmental pollution, the solvent is removed.

  Conventionally, there is a solvent removal apparatus that separates and removes a solvent from a gas containing an organic solvent. This device adsorbs the organic solvent to the adsorbent in the adsorption process, switches to the desorption process before the adsorption amount of the adsorbent reaches saturation, desorbs and recovers the organic solvent from the adsorbent with water vapor, regenerates the adsorbent, A solvent removal apparatus used again for the adsorption process is mainly used. As an adsorbent used for the organic solvent, a solvent removing apparatus using activated carbon fiber (ACF), in which the adsorption / desorption of the solvent is faster than the adsorbent such as conventional activated carbon, is used. Since ACF has a property that drying is performed faster than conventional activated carbon, the drying process after the desorption process using water vapor, which is conventionally required, can be performed simultaneously with the adsorption process using the gas to be processed. Therefore, the solvent removal apparatus using ACF as the adsorbent has an advantage that it is not necessary to provide a drying process substantially independently and can be omitted.

  However, when an organic solvent is removed from a small amount of gas to be processed containing a high concentration organic solvent, the amount of ACF increases in proportion to the amount of the organic solvent to be processed. Furthermore, since the flow rate of the gas to be treated relative to the amount of ACF is small, the drying performed simultaneously with the adsorption in the adsorption process is not sufficiently performed, and the ACF as the ACF is used in a state containing moisture. For this reason, there is a problem that the adsorption efficiency of ACF is lowered, and the content of the organic solvent contained in the exhaust gas discharged from the solvent removing device is increased.

  In order to improve this problem, the flow rate of the gas to be treated is increased by diluting the gas to be treated containing a high-concentration organic solvent with outside air as described in Patent Document 1, and the adsorbent in the adsorption process is increased. A method of promoting drying is generally performed. However, the saturated adsorption amount of the organic solvent with respect to the adsorbent is proportional to the concentration of the organic solvent contained in the gas to be treated. Therefore, the method of diluting a gas to be processed containing a high concentration organic solvent with outside air has a problem that the processing efficiency is lowered.

  Patent Document 2 discloses a method of installing a drying process between a desorption process and an adsorption process. However, this method uses three adsorption cans filled with the same amount of adsorbent in parallel to perform each step, increasing the amount of adsorbent to be used and increasing the equipment cost. There is an inconvenience.

Japanese Patent No. 3183281 (paragraph [0005]) JP-A-61-35822 (page 1, lower right column, line 4 to page 2, upper left column, line 9)

  The present invention is a low boiling point organic solvent removal apparatus equipped with an organic solvent adsorption tank filled with ACF as an adsorbent, and improves the removal efficiency of the organic solvent in the exhaust gas containing a high concentration organic solvent, and also has an adsorption capability of ACF. It is an object of the present invention to provide an organic solvent removal method and removal device that maximizes the cost and reduces running costs and device manufacturing costs. That is, when the concentration of the organic solvent in the treated gas is equivalent to that of the prior art, the total amount of ACF filled in the adsorption tank can be reduced, and the total amount of ACF filled in the adsorption tank is equivalent to that of the conventional technique. The object of the present invention is to reduce the concentration of the organic solvent in the treated gas.

  The present inventor has repeatedly studied to solve the above problems. As a result, the organic solvent contained in the gas to be treated is adsorbed on the activated carbon fiber, and the organic solvent removing device for separating and removing the organic solvent is composed of the first adsorption tank and the second adsorption tank, and these two tanks are connected in series. And a connecting pipe connecting the first adsorption tank and the second adsorption tank to a predetermined range in the mass ratio of the activated carbon fibers filled in the first adsorption tank and the second adsorption tank. By providing a condenser, it has been found that an organic solvent removal device capable of increasing the adsorption amount and reducing the organic solvent discharge concentration at the outlet of the second adsorption tank can be realized, and the present invention has been completed. It was.

  The present invention for solving the above problems is described below.

[1] a first adsorption tank filled with activated carbon fibers;
The second adsorption tank filled with activated carbon fibers that are the same as or different from the activated carbon fibers, wherein the mass (M ₂ ) of activated carbon fibers filled in the second adsorption tank is filled in the first adsorption tank. A second adsorption tank filled with activated carbon fibers of 0.05 to 0.25 in a mass ratio (M ₂ / M ₁ ) based on the mass (M ₁ ) of the carbon fibers;
A connecting pipe connecting the first adsorption tank and the second adsorption tank;
A condenser interposed in the connecting pipe;
Steam injection means provided in each of the first adsorption tank and the second adsorption tank;
An organic solvent removing apparatus having

[2] A method for removing an organic solvent in a gas to be treated using the organic solvent removing apparatus according to [1],
By supplying the gas to be treated containing 3000 ppm or more of the organic solvent to the first adsorption tank and adsorbing the organic solvent to the activated carbon fiber filled therein, and drying the condensed water contained in the activated carbon fiber, A first adsorption tank treatment gas containing 500 ppm or less of an organic solvent and moisture is obtained, and then this first adsorption tank treatment gas is supplied to a condenser to condense and separate the moisture in the first adsorption tank treatment gas to the outside of the system. While discharging, supplying the first adsorption tank processing gas from which the water has been separated to the second adsorption tank, the organic solvent contained in the first adsorption tank treatment gas is adsorbed to the activated carbon fibers filled in the second adsorption tank And an adsorption step of discharging the second adsorption tank treatment gas having an organic solvent concentration of 100 ppm or less to the outside by drying the moisture contained in the activated carbon fiber,
After the supply of the gas to be processed to be supplied to the first adsorption tank is stopped, steam is supplied into the first adsorption tank and the second adsorption tank by the steam injection means, and the first adsorption tank and the second adsorption tank are filled. By desorbing the adsorbed organic solvent of each activated carbon fiber, each activated carbon fiber adsorbing the organic solvent is regenerated to activated carbon fiber containing condensed water generated by condensation of the supplied steam. A desorption step of taking out the desorbed organic solvent out of the system;
The method of removing the organic solvent in the gas to be processed that repeats alternately.

[3] The activated carbon fiber filled in the first adsorption tank has a specific surface area of 1200 m ² / g to 2000 m ² / g, an average pore diameter of 1 to 4 nm, and a total pore volume of 0.2 to 0.8 cm ³ / The method for removing an organic solvent according to [2], which is an activated carbon fiber of g.

[4] The activated carbon fiber filled in the second adsorption tank has a specific surface area of 600 m ² / g or more and less than 1400 m ² / g, an average pore diameter of 0.5 to 3 nm, and a total pore volume of 0.1 to 0.6 cm. ^The method for removing an organic solvent according to [2], wherein the organic solvent is ³ / g of activated carbon fiber.

  [5] The method for removing an organic solvent according to [2], wherein the gas to be treated supplied to the first adsorption tank is a gas to be treated containing 5000 to 100,000 ppm of an organic solvent having a boiling point of 30 to 70 ° C.

  The organic solvent removal apparatus according to the present invention includes an organic solvent adsorption tank that separates and removes an organic solvent contained in a gas to be treated, and two tanks, a first adsorption tank and a second adsorption tank, are arranged in series. A mass ratio of the activated carbon fibers filled in the adsorption tank and the second adsorption tank is set within a predetermined range, and further, a condenser interposed in a connecting pipe connecting the first adsorption tank and the second adsorption tank is provided. In addition, since the water vapor discharged from the first adsorption tank is discharged to the outside, the second adsorption tank can be sufficiently dried with a relatively small amount of gas to be treated. As a result, the second adsorption tank treatment gas The organic solvent discharge concentration can be controlled to a low concentration of 100 ppm or less.

It is a graph which shows the isothermal adsorption curve of the relationship between the organic-solvent density | concentration contained in to-be-processed gas, and the saturated adsorption amount of the organic solvent to activated carbon fiber. It is a system flowchart which shows an example of the removal apparatus of the organic solvent of this invention. It is a system flow figure which shows the other example of the removal apparatus of the organic solvent of this invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

As mentioned above, the organic solvent removal device
Two organic solvent adsorption tanks for adsorbing an organic solvent contained in the gas to be treated on the activated carbon fiber (ACF) as an adsorbent and separating and removing the organic solvent are arranged in series as a first adsorption tank and a second adsorption tank. A device,
Mass ratio (M ₂ / M ₁ ) between the mass (M ₁ ) of ACF filled in the first adsorption tank and the mass (M ₂ ) filled in the second adsorption tank of the same or different ACF as the ACF Is 0.05 to 0.25, preferably 0.1 to 0.25,
A connecting pipe connecting the first adsorption tank and the second adsorption tank;
A condenser interposed in the connecting pipe;
Steam injection means provided in each of the first adsorption tank and the second adsorption tank;
By using the apparatus having the ACF, the ACF adsorption ability can be maximized as follows.

  FIG. 1 is a graph showing an isothermal adsorption curve of the relationship between the concentration of the organic solvent contained in the gas to be treated and the saturated adsorption amount of the organic solvent on the ACF.

As shown in FIG. 1, the saturated adsorption amount of the organic solvent on the ACF is proportional to the concentration of the organic solvent contained in the gas to be processed. Therefore, in the case of a gas to be processed containing a high concentration organic solvent, a high saturation adsorption rate can be obtained, and high processing efficiency can be expected. For example, when a phenolic ACF having a specific surface area of 1500 m ² / g is used as an adsorbent, the organic solvent (methylene chloride) concentration in the gas to be treated is 5000 ppm or more, preferably 10000 to 100000 ppm. On the other hand, the saturated adsorption amount of ACF is expected to be 35% or more.

  Hereinafter, steam is supplied to an adsorption tank filled with ACF, and a desorption process for desorbing and removing the organic solvent adsorbed on the ACF, and a gas to be processed is supplied to the ACF from which the steam is supplied and the organic solvent is desorbed and removed. Thus, an organic solvent removal method having an adsorption step of adsorbing the organic solvent in the gas to be treated to the partially wet ACF while drying the wet ACF by condensing steam is considered. .

  In such a method of removing an organic solvent using ACF in a partially wet state, the adsorption process is complicated because the ACF drying and the organic solvent adsorption occur simultaneously. This is different from the adsorption phenomenon of dried ACF.

  In the above removal method, when the organic solvent is removed by adsorption with ACF from the gas to be treated containing the organic solvent, the higher the concentration of the organic solvent in the gas to be treated, the higher the concentration of the organic solvent to be adsorbed. As a result, the amount of ACF used increases. In this case, the flow rate of the gas to be processed relative to the amount of ACF used is relatively small. As a result, the flow rate necessary for drying the wet ACF in the adsorption process is not given, and the ACF becomes excessively watery. As a result, the adsorption efficiency of the organic solvent at the initial stage of the adsorption process is lowered.

  That is, in the above removal method, a certain equilibrium exists between the saturated adsorption amount of the organic solvent with respect to ACF and the water content of ACF. Therefore, the concentration of the organic solvent in the processing gas discharged from the outlet of the adsorption tank with respect to the water content of ACF is kept at an equilibrium value.

  In the conventional organic solvent treatment system, a dilution gas is introduced in order to obtain the flow rate of the gas to be treated necessary for drying the ACF and to keep the concentration of the organic solvent (methylene chloride) at the outlet of the organic solvent adsorption tank low. The concentration of the organic solvent contained in the gas to be treated introduced into the organic solvent adsorption tank must be less than 5000 ppm, and actually 1000 ppm or less. In this case, the saturated adsorption amount can be expected to be only about 18% with reference to FIG. That is, in the conventional method, since the organic solvent treats a low-concentration gas, the ACF adsorption capacity is reduced to about half.

  On the other hand, in the organic solvent removal method of the present invention, the first adsorption tank processing gas containing the low concentration organic solvent discharged from the first adsorption tank is further processed in the second adsorption tank. Therefore, the to-be-processed gas containing the high concentration organic solvent can be introduced into the first adsorption tank. The concentration of the organic solvent in the gas to be treated at the inlet of the first adsorption tank is preferably 5000 ppm or more, more preferably 10,000 to 100,000 ppm. By setting the concentration of the organic solvent in the gas to be treated to 5000 ppm or more, the saturated adsorption amount of the organic solvent to the ACF becomes 30% or more according to the graph of FIG. 1, and the treatment can be performed with high adsorption efficiency.

  Considering only this operation, the first adsorption tank filled with ACF can draw out the adsorption capacity of ACF twice that of the conventional organic solvent treatment system.

  In other words, the filling amount of ACF is reduced to half, and the facility cost is naturally reduced to half of the utility for regenerating ACF.

  Specifically, the total amount of the ACF filling amount in the first adsorption tank and the ACF filling amount in the second adsorption tank is 52 with respect to the ACF filling amount in the conventional organic solvent adsorption tank of only one tank. Reduced to 5-62.5 wt%, at least 60-62.5 wt%.

  In proportion to the reduction in the ACF filling amount, the energy related to ACF regeneration is also reduced.

  In addition, it is preferable to make the organic solvent density | concentration in the 1st adsorption tank process gas containing the organic solvent discharged | emitted from a 1st adsorption tank into 10-1000 ppm, and it is more preferable to set it as 100-200 ppm.

  Examples of the organic solvent contained in the gas to be used for the organic solvent removal method of the present invention include halogenated hydrocarbon organic solvents such as methylene chloride, chloroform, 1,1-dichloroethylene having a boiling point of 30 to 70 ° C., methylal Suitable are ethers such as methyl-t-butyl ether or acetal organic solvents, ester organic solvents such as methyl acetate and ethyl acetate, and ketone organic solvents such as acetone and methyl ethyl ketone.

  According to the organic solvent removing apparatus of the present invention, a condenser is interposed in the connecting pipe connecting the first adsorption tank and the second adsorption tank, whereby the amount of water in the first adsorption tank treatment gas is increased. This is advantageous for drying the ACF after the desorption treatment of the second adsorption tank. The temperature drop at the inlet and outlet of the condenser is preferably 15 to 35 ° C, more preferably 20 to 35 ° C. The condenser removes 35 to 65% of the amount of water in the first adsorption tank processing gas.

  In addition, by setting the mass ratio of the ACF filled in the first adsorption tank and the ACF filled in the second adsorption tank to the above range, the first adsorption tank treatment gas introduced into the second adsorption tank The flow rate is sufficient to dry the ACF in the second adsorption tank after the desorption process.

  Therefore, in the second adsorption tank, after the desorption process, the ACF in the second adsorption tank is quickly dried by the first adsorption tank treatment gas in the adsorption process without providing a drying process independently as in the conventional method. Thus, the solvent can be removed efficiently.

When the mass ratio (M ₂ / M ₁ ) between the mass (M ₁ ) of the ACF in the first adsorption tank and the mass (M ₂ ) of the ACF in the second adsorption tank is less than 0.05, This is not preferable because the organic solvent adsorption treatment is insufficient and the amount of the organic solvent contained in the second adsorption tank treatment gas increases. If the mass ratio (M ₂ / M ₁ ) of the ACF mass (M ₁ ) of the first adsorption tank and the ACF mass (M ₂ ) of the second adsorption tank exceeds 0.25, The first adsorption tank processing gas flow rate required for drying the ACF is not provided, resulting in insufficient drying. As a result, since the ACF in the second adsorption tank becomes excessive in moisture, the adsorption efficiency is lowered, and the content of the organic solvent contained in the processing gas (treated gas) discharged from the second adsorption tank is increased. It is not preferable.

  As described above, the method and apparatus for removing an organic solvent of the present invention realizes the purpose of increasing the use efficiency of ACF as an adsorbent, reducing the amount of ACF used, and eventually reducing the size of the apparatus. It is.

  Next, embodiments of the present invention will be described.

  FIG. 2 is a system flow diagram showing an example of the organic solvent removing apparatus of the present invention. The organic solvent removal apparatus of the present invention can be broadly divided into (A) a first adsorption tank capable of performing adsorption and desorption from an ACF by batch processing, and separating and removing the organic solvent; (B) From the second adsorption tank for performing the adsorption and desorption from the ACF of the organic solvent contained in the gas treated in the first adsorption tank (first adsorption tank treatment gas) by ACF. It has an adsorption removal means series configured.

  As shown in FIG. 2, in the organic solvent removal apparatus of this example, two adsorption removal means series capable of performing adsorption removal of organic compounds are provided. An operation of adsorbing an organic compound is performed in one of the adsorption removal means series (first adsorption tank A, second adsorption tank B). Meanwhile, an operation of desorbing and removing the organic compounds adsorbed in the other adsorption removal means series (first adsorption tank A ′, second adsorption tank B ′) is performed. When the adsorption / removal capacity of one series is below a preset limit, an operation to desorb and remove the adsorbed organic compound by one adsorption / removal means series is performed, while the organic compound is removed by the other adsorption / removal means series. The operation of adsorbing is alternately performed.

  The function of one adsorption removal means series (first adsorption tank A, second adsorption tank B) and the other adsorption removal means series (first adsorption tank A ′, second adsorption tank B ′) is substantially the same. Therefore, the mechanical elements of each are substantially the same. Accordingly, in the following description, mechanical elements performing the same function are distinguished from each other by adding a dash (').

  As shown in FIG. 2, the gas to be treated containing 5000 ppm or more, preferably 10,000 to 100,000 ppm of an organic solvent such as exhaust gas from a factory or work place is conveyed through the first adsorption tank introduction line 4 by the blower 2, It is introduced into the first adsorption tank main body 8 filled with ACF 6 in the first adsorption tank A.

As ACF6, the adsorption capacity is 0.05 to 0.5 g in terms of the adsorption amount of the organic solvent with respect to 1 g of ACF, and the specific surface area is preferably 1200 to 2000 m ² / g. The specific surface area is 1400 to 2000 m ^2. / G is more preferable, and 1450 to 1600 m ² / g is particularly preferable.

According to FIG. 1, when the organic solvent concentration of the gas to be treated is 1000 ppm or more, the adsorption rate increases as the specific surface area increases. Therefore, when the concentration of the organic solvent in the gas to be treated is 1000 ppm or more, it is more preferable that the specific surface area is 1200 m ² / g or more, because the adsorption rate of the solvent becomes high. If the specific surface area is a value of 1200 m ² / g or more, it is preferable because high molecular weight organic compounds that could not be removed by a conventional solvent removal apparatus can also be collected. However, when the specific surface area exceeds 2000 m ² / g, the average pore diameter becomes too large, the interaction between the solvent molecules and the pores is weak, and the solvent tends to leak.

The amount of ACF6 adsorbed in the first adsorption tank A is highly correlated with the average pore diameter and the total pore volume. Therefore, ACF6 preferably has an average pore diameter in the range of 1 to 4 nm, more preferably 3 to 4 nm. ACF6 preferably has a total pore volume of 0.3 to 0.6 cm ³ / g, more preferably 0.5 to 0.6 cm ³ / g.

  The ACF used in the present invention has an average pore diameter, total pore volume, and specific surface area suitable for the organic compound to be adsorbed for both ACF6 and ACF26 described later, polyacrylonitrile (PAN), pitch It can be used regardless of the type of cellulose, cellulose and phenol. In these ACFs used in the present invention, especially in the case of phenol-based ACF, the larger the specific surface area, the larger the average pore diameter, so that a polymer having a large molecular diameter can be adsorbed and desorbed, and the pores can be blocked. And a decrease in ACF adsorption performance can be suppressed.

  The first adsorption tank main body 8 is arranged in two or more tanks (two tanks in this example). For example, in the case of two tanks, the suction valves 10 and 10 'and the discharge valves 12 and 12' are switched alternately. By alternately switching the steam valves 14 and 14 ', the first adsorption tank main body 8 and 8' is continuously adsorbed or desorbed.

  Hereinafter, one first adsorption tank A will be mainly described.

  The adsorption process may be performed without performing a cooling / drying process using a special cooling / drying gas after the desorption process by steam heating. In particular, since ACF6 has micropores on the outer surface, simply introducing an organic solvent-containing gas as a gas to be treated advances cooling and drying, and its adsorption activity gradually increases.

  In the desorption process, the organic solvent adsorbed on the first adsorption tank main body 8 in the adsorption process described later is steamed to the first adsorption tank main body 8 through the first adsorption tank side steam introduction line 16, the steam valve 14, and the steam injection means 15. Is introduced, whereby ACF 6 is regenerated and the organic solvent-containing first adsorption tank desorption gas is generated. The regenerated ACF 6 is regenerated in a wet state containing moisture condensed from the injected steam.

  The organic solvent-containing first adsorption tank desorption gas is introduced into the condenser 22 together with the organic solvent-containing second adsorption tank desorption gas described later through the first adsorption tank side desorption gas valve 18 and the first adsorption tank side recovery line 20. A condensation treatment with cooling water is performed, and a recovered organic solvent is obtained as a condensate. On the other hand, the uncondensed component is mixed into the gas to be processed (X in FIG. 2).

  In the adsorption step, the gas to be treated is sent to the first adsorption tank A, and when the organic solvent is adsorbed here, the first adsorption tank treatment gas is discharged simultaneously. The first adsorption tank processing gas is sent to the condenser 25 through a first adsorption tank processing gas transport line (a connecting pipe connecting the first adsorption tank and the second adsorption tank) 24.

  The first adsorption tank processing gas is a gas discharged from the first adsorption tank A after the steam injected in the desorption process is condensed and the ACF 6 in a wet state is dried. Therefore, the first adsorption tank processing gas contains moisture to near saturation. The first adsorption tank processing gas containing moisture is introduced into the second adsorption tank B after the vapor derived from steam is condensed and separated by the condenser 25.

  The amount of water condensed and separated by the condenser 25 is preferably at least 30% of the total amount of water contained in the first adsorption tank processing gas. In the second adsorption tank B, the second adsorption tank treatment gas from which the organic solvent contained in the first adsorption tank treatment gas is removed by adsorption is discharged to the outside.

  Similar to the first adsorption tank main body 8, the second adsorption tank main body 28 is also arranged in two or more tanks (in this example, two tanks). For example, in the case of two tanks, the suction valves 30, 30 ′ and By alternately switching the discharge valves 32 and 32 ′ and alternately switching the steam valves 34 and 34 ′, any of the second adsorption tank main bodies 28 and 28 ′ is configured to perform adsorption or desorption. .

  Hereinafter, one second adsorption tank B will be mainly described.

As the ACF 26, an ACF having an adsorption capacity of 0.05 to 0.5 g in terms of the adsorption amount of the organic solvent with respect to 1 g of ACF and a specific surface area of 600 m ² / g or more and less than 1400 m ² / g is preferable. more preferably less than 700 meters ² / g or more 1400 m ² / g, still more preferably ^{1100~1350m 2 / g, 1200~1350m 2 /} g is particularly preferred.

The amount of ACF6 adsorbed in the first adsorption tank A is highly correlated with the average pore diameter and the total pore volume. Therefore, ACF6 preferably has an average pore diameter in the range of 1 to 4 nm, more preferably 3 to 4 nm. ACF6 preferably has a total pore volume of 0.3 to 0.6 cm ³ / g, more preferably 0.5 to 0.6 cm ³ / g.

ACF26 preferably has an average pore diameter of 0.5 to ³ nm and a total pore volume of 0.1 to 0.6 cm ³ / g, an average pore diameter of 1 to 2.5 nm, More preferably, the pore volume is 0.2 to 0.4 cm ³ / g.

  By combining the ACF 6 and ACF 26 as described above, the ACF adsorption ability can be maximized as described above.

  The organic solvent adsorbed on the second adsorption tank main body 28 is desorbed by introducing steam into the second adsorption tank main body 28 through the second adsorption tank side steam introduction line 36, the steam valve 34, and the steam injection means 35. As a result, the ACF is regenerated and the organic solvent-containing second adsorption tank desorption gas is generated. The organic solvent-containing first adsorption tank desorption gas is introduced into the condenser 22 together with the organic solvent-containing first adsorption tank desorption gas through the second adsorption tank-side desorption gas valve 38 and the second adsorption tank-side recovery line 40. Then, a condensation treatment with cooling water is performed, and a recovered organic solvent is obtained as a condensed component. On the other hand, the uncondensed component is mixed into the gas to be processed (X in FIG. 2).

  In the adsorption step, the second adsorption tank processing gas discharged after the organic solvent is adsorbed and removed is out of the system as a cleaning gas whose organic solvent concentration is controlled to 100 ppm or less, preferably 60 ppm or less, more preferably 30 ppm or less. Discharged.

  In addition, you may introduce | transduce the 2nd adsorption tank process gas into the backup process tank (not shown) which can carry out the adsorption process of the organic solvent through the 2nd adsorption tank process gas transport line 42 as needed.

  The backup processing tank has a main body of a backup processing tank that is a drum-type organic solvent processing mechanism that has a large number of passages formed by processing a sheet carrying an adsorbent on heat-resistant paper into a honeycomb shape. Is mentioned. Examples of the adsorbent supported in the backup processing tank include ACF and zeolite.

  In the example of FIG. 2, two condensers 25 and 25 ′ are provided. However, as in the example of FIG. 3, one condenser 25 is provided, and when switching between the adsorption process and the desorption process. The condenser 25 may be switched for use. The example of FIG. 3 is more preferable because the equipment cost can be reduced.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

In addition, the specific surface area of ACF, the average pore diameter, and the total pore volume were measured on condition of the following using the fully automatic gas adsorption amount measuring apparatus (ATOSORB-1 by Quantachrome Instruments).
Adsorption gas: Nitrogen adsorption temperature: Liquid nitrogen temperature (-196 ° C)
Measurement range: P / P ₀ = 0.00 to 0.99
The specific surface area was calculated from the obtained adsorption isotherm using the BET method. The total pore volume was calculated by liquid conversion of the amount of adsorption near the relative pressure of 1.0. The average pore diameter was calculated from the total pore volume and specific surface area according to the following formula (1).
Average pore diameter = 4 × total pore volume / specific surface area (1)
[Example 1]
As shown in FIG. 3, Table 1 and the following conditions, the first adsorption tank A filled with ACF6 and the second adsorption tank B filled with ACF26 are used, and contain 20000 ppm of methylene chloride (boiling point 40 ° C.) as an organic solvent. The gas to be treated was subjected to adsorption treatment at ³ Nm ³ / min for 8 minutes. The ACFs 6 and 26 after the adsorption treatment were desorbed for 6 minutes at an ACF regeneration steam amount of 13 kg / h. Note that the gas to be treated was continuously treated by alternately performing adsorption / desorption treatment using two series of adsorption removal means.

The ACF 6 used in the first adsorption tank A had a packed mass (M ₁ ) of 5 kg, a specific surface area of 1500 m ² / g, an average pore diameter of 1.5 nm, and a total pore volume of 0.55 cm ³ / g. It was. The ACF 26 used in the second adsorption tank B has a filling mass (M ₂ ) of 0.5 kg, a specific surface area of 1300 m ² / g, an average pore diameter of 0.5 nm, and a total pore volume of 0.3 cm ³ / g. Met. The ACF filling mass ratio (M ₂ / M ₁ ) between the first adsorption tank A and the second adsorption tank B was 0.1. Note that phenolic ACF (manufactured by Toho Kako Construction Co., Ltd.) was used for both ACF 6 and 26.

  The temperature drop at the inlet and the outlet in the condenser 25 interposed in the connecting pipe 24 connecting the first adsorption tank A and the second adsorption tank B was set to 20 ° C.

  In this adsorption / desorption test, the methylene chloride concentration (treated gas concentration) in the first adsorption tank treatment gas 1 hr after the start of the adsorption treatment, and the total amount of organic solvent discharged over the adsorption treatment 1 hr (organic solvent emissions) Table 1 shows the measurement results of the amount of steam for ACF regeneration. As a result, the concentration of the organic solvent in the second adsorption tank treatment gas (treated gas) was as low as 10 ppm, and the methylene chloride discharge was as low as 7 g / h.

  Further, the amount of steam for ACF regeneration was as low as 25 kg / h, and the desorption treatment was efficient.

[Example 2]
As shown in Table 1 and the following conditions, each of ACF6 and ACF26 has a specific surface area of 1500 m ² / g, an average pore diameter of 1.5 nm, and a total pore volume of 0.55 cm ³ / g. Were operated as in Example 1.

  As a result of this adsorption / desorption test, the methylene chloride concentration in the treated gas was as low as 50 ppm, and the methylene chloride discharge was as low as 35 g / h.

  Further, the amount of steam for ACF regeneration was as low as 25 kg / h, and the desorption treatment was efficient.

[Example 3]
As shown in Table 1 and the following conditions, ACFs 6 and 26 were operated in the same manner as in Example 1 except that pitch-based ACF (manufactured by Toho Kako Construction Co., Ltd.) was used.

The ACF 6 used in the first adsorption tank A has a pitch with a packing mass (M ₁ ) of 5 kg, a specific surface area of 1500 m ² / g, an average pore diameter of 1.3 nm, and a total pore volume of 0.5 cm ³ / g. System ACF. The ACF 26 used in the second adsorption tank B has a filling mass (M ₂ ) of 0.5 kg, a specific surface area of 1500 m ² / g, an average pore diameter of 1.3 nm, and a total pore volume of 0.5 cm ³ / g. The pitch ACF. The ACF filling mass ratio (M ₂ / M ₁ ) between the first adsorption tank A and the second adsorption tank B was 0.1.

  As a result of this adsorption / desorption test, the methylene chloride concentration in the treated gas was as low as 50 ppm, and the methylene chloride discharge was as low as 35 g / h.

  Further, the amount of steam for ACF regeneration was as small as 27 kg / h, and the desorption treatment was efficient.

[Example 4]
As shown in Table 1 and the following conditions, ACFs 6 and 26 were operated in the same manner as in Example 1 except that PAN-based ACF (manufactured by Toho Kako Construction Co., Ltd.) was used.

The ACF 6 used in the first adsorption tank A has a filling mass (M ₁ ) of 5 kg, a specific surface area of 1500 m ² / g, an average pore diameter of 1.3 nm, and a total pore volume of 0.5 cm ³ / g. System ACF. The ACF 26 used in the second adsorption tank B has a filling mass (M ₂ ) of 0.5 kg, a specific surface area of 1500 m ² / g, an average pore diameter of 1.3 nm, and a total pore volume of 0.5 cm ³ / g. PAN-based ACF. The ACF filling mass ratio (M ₂ / M ₁ ) between the first adsorption tank A and the second adsorption tank B was 0.1.

  As a result of this adsorption / desorption test, the methylene chloride concentration in the treated gas was as low as 80 ppm, and the methylene chloride discharge was as low as 56 g / h.

  Moreover, the amount of steam for ACF regeneration was as low as 29 kg / h, and the desorption treatment was efficient.

[Example 5]
As shown in Table 1 and the following conditions, except that phenolic ACF (manufactured by Toho Kako Construction Co.) was used for ACF6 and PAN-based ACF (manufactured by Toho Kako Construction Co.) was used for ACF26, the same as in Example 1 Operated.

The ACF 6 used in the first adsorption tank A is a phenol having a filling mass (M ₁ ) of 5 kg, a specific surface area of 1500 m ² / g, an average pore diameter of 1.5 nm, and a total pore volume of 0.55 cm ³ / g. System ACF. The ACF 26 used in the second adsorption tank B has a filling mass (M ₂ ) of 0.5 kg, a specific surface area of 1500 m ² / g, an average pore diameter of 1.3 nm, and a total pore volume of 0.5 cm ³ / g. PAN-based ACF. The ACF filling mass ratio (M ₂ / M ₁ ) between the first tank A and the second adsorption tank B was 0.1.

  As a result of this adsorption / desorption test, the methylene chloride concentration in the treated gas was as low as 80 ppm, and the methylene chloride discharge was as low as 56 g / h.

  Further, the amount of steam for ACF regeneration was as small as 27 kg / h, and the desorption treatment was efficient.

[Comparative Example 1]
As shown in Table 2 and the following conditions, the same operation as in Example 1 was performed except that only one adsorption tank filled with ACF was subjected to adsorption / desorption treatment.

The ACF used in the organic solvent adsorption tank had a filling mass of 5.5 kg, a specific surface area of 1500 m ² / g, an average pore diameter of 1.5 nm, and a total pore volume of 0.55 cm ³ / g.

  As a result of this adsorption / desorption test, the methylene chloride concentration in the treated gas was as high as 200 ppm, and the methylene chloride discharge was as high as 140 g / h.

  Further, the amount of steam for ACF regeneration was as high as 33 kg / h, and the desorption treatment was inefficient.

[Example 6]
As shown in Table 2 and the following conditions, the same operation as in Example 1 was performed except that the methylene chloride concentration in the gas to be treated was changed to 50000 ppm.

  As a result of the adsorption / desorption test, the methylene chloride concentration in the treated gas was as low as 20 ppm, and the methylene chloride discharge was as low as 7 g / h.

  Further, the amount of steam for ACF regeneration was as low as 25 kg / h, and the desorption treatment was efficient.

[Comparative Example 2]
As shown in Table 2 and the following conditions, the same operation as in Example 6 was carried out except that only one adsorption tank filled with ACF was subjected to adsorption / desorption treatment.

The ACF used in the organic solvent adsorption tank had a packed mass of 8 kg, a specific surface area of 1500 m ² / g, an average pore diameter of 1.5 nm, and a total pore volume of 0.55 cm ³ / g.

  As a result of this adsorption / desorption test, the methylene chloride concentration in the treated gas was as high as 500 ppm and the methylene chloride discharge was as high as 175 g / h, although a large amount of ACF was used as compared with Example 6. It became.

  Further, the amount of steam for ACF regeneration was as high as 33 kg / h, and the desorption treatment was inefficient.

[Example 7]
As shown in Table 2 and the following conditions, the same operation as in Example 1 was performed except that a gas to be treated containing 20000 ppm of chloroform (boiling point 61 ° C.) was used as the organic solvent.

  As a result of this adsorption / desorption test, the chloroform concentration in the treated gas was as low as 50 ppm, and the amount of chloroform discharged was as low as 28 g / h.

  Further, the amount of steam for ACF regeneration was as low as 25 kg / h, and the desorption treatment was efficient.

[Comparative Example 3]
As shown in Table 2 and the following conditions, the same operation as in Example 7 was carried out except that only one adsorption tank filled with ACF was subjected to adsorption / desorption treatment.

The ACF used in the organic solvent adsorption tank had a packed mass of 8 kg, a specific surface area of 1500 m ² / g, an average pore diameter of 1.5 nm, and a total pore volume of 0.55 cm ³ / g.

  As a result of this adsorption / desorption test, the chloroform concentration in the treated gas is as high as 300 ppm and the chloroform discharge amount is as high as 170 g / h, although a large amount of ACF is used as compared with Example 7. It became.

  Further, the amount of steam for ACF regeneration was as high as 33 kg / h, and the desorption treatment was inefficient.

[Example 8]
As shown in Table 3 and the following conditions, the flow rate of the gas to be treated is 220 Nm ³ / h, and with the increase in the flow rate of the gas to be treated, the ACF filling amount is 6 kg in the first adsorption tank A (M ₁ ) and the second adsorption. 0.6 kg in the tank B (M ₂ ) [ACF filling mass ratio between the first tank A and the second tank B (M ₂ / M ₁ )... 0.1], and the whole (M ₁ + M ₂ ) 6. The same operation as in Example 1 was performed except that 6 kg was used.

  As a result of this adsorption / desorption test, the methylene chloride concentration in the treated gas was as low as 10 ppm, and the methylene chloride discharge was as low as 10 g / h.

  Moreover, although the amount of steam for ACF regeneration was 29 kg / h, which was increased as compared with Example 1 with an increase in the amount of ACF used, the desorption treatment efficiency was sufficiently good.

[Comparative Example 4]
As shown in Table 3 and the following conditions, the same operation as in Example 8 was performed except that only one adsorption tank filled with ACF was subjected to adsorption / desorption treatment.

The ACF used in the organic solvent adsorption tank had a filling mass of 12 kg, a specific surface area of 1500 m ² / g, an average pore diameter of 1.5 nm, and a total pore volume of 0.55 cm ³ / g.

  As a result of this adsorption / desorption test, even when 12 kg and a large amount of ACF were used, the methylene chloride concentration in the treated gas was as high as 300 ppm, and the methylene chloride discharge was as high as 300 g / h.

  Moreover, the amount of steam for ACF regeneration was as high as 52 kg / h, and the desorption treatment was inefficient.

[Example 9]
As shown in Table 4 and the following conditions, the ACF filling amount is 5 kg in the first adsorption tank A (M ₁ ) and 0.3 kg in the second adsorption tank B (M ₂ ) [the first adsorption tank A and the second The same operation as in Example 1 was performed except that the ACF filling mass ratio with the adsorption tank B (M ₂ / M ₁ ) 0.06] and the total (M ₁ + M ₂ ) were 5.3 kg.

  As a result of this adsorption / desorption test, the methylene chloride concentration in the treated gas was as low as 10 ppm, and the methylene chloride discharge was as low as 7 g / h.

  Further, the amount of steam for ACF regeneration was 23 kg / h, and the desorption treatment was efficient.

[Comparative Example 5]
As shown in Table 4 and the following conditions, the ACF filling amount is 5 kg in the first adsorption tank A (M ₁ ) and 0.2 kg in the second adsorption tank B (M ₂ ) [the first adsorption tank A and the second The same operation as in Example 1 was performed except that the ACF filling mass ratio with the adsorption tank B (M ₂ / M ₁ ) 0.04] and the total (M ₁ + M ₂ ) were 5.2 kg.

  As a result of this adsorption / desorption test, the methylene chloride concentration in the treated gas was as high as 150 ppm, and the methylene chloride discharge was as high as 105 g / h.

[Example 10]
As shown in Table 4 and the following conditions, the ACF filling amount is 5 kg in the first adsorption tank A (M ₁ ) and ₁ kg in the second adsorption tank B (M ₂ ) [the first adsorption tank A and the second adsorption tank. ACF filling mass ratio with B (M ₂ / M ₁ )... 0.2], and the total (M ₁ + M ₂ ) was 6 kg.

  As a result of this adsorption / desorption test, the methylene chloride concentration in the treated gas was as low as 20 ppm, and the methylene chloride discharge was as low as 14 g / h.

  Moreover, the amount of steam for ACF regeneration was as small as 24 kg / h, and the desorption treatment was efficient.

[Comparative Example 6]
As shown in Table 4 and the following conditions, the ACF filling amount is 4.5 kg in the first adsorption tank A (M ₁ ), 1.5 kg in the second adsorption tank B (M ₂ ) (the first adsorption tank A, The same operation as in Example 1 was carried out except that the ACF filling mass ratio with the second adsorption tank B (M ₂ / M ₁ ) 0.333] and the total (M ₁ + M ₂ ) was 6 kg.

  As a result of this adsorption / desorption test, the amount of steam for ACF regeneration was as small as 23 kg / h, and the desorption treatment was efficient, but the drying of the second adsorption tank B became insufficient, and as a result, the treated gas The methylene chloride concentration in the inside was as high as 150 ppm, and the methylene chloride discharge was as high as 105 g / h.

[Example 11]
As shown in Table 2 and the following conditions, the same operation as in Example 1 was performed except that a gas to be treated containing 20000 ppm of methylal (boiling point: 42.5 ° C.) as an organic solvent was used.

  As a result of this adsorption / desorption test, the methylal concentration in the treated gas was as low as 80 ppm, and the methylal discharge was also as low as 49 g / h.

  Moreover, the amount of steam for ACF regeneration was 29 kg / h, and the desorption treatment was efficient.

[Example 12]
As shown in Table 2 and the following conditions, the same operation as in Example 1 was performed except that a gas to be treated containing 20000 ppm of methyl acetate (boiling point 54 ° C.) was used as the organic solvent.

  As a result of this adsorption / desorption test, the methyl acetate concentration in the treated gas was as low as 80 ppm, and the methyl acetate discharge was as low as 48 g / h.

  Further, the amount of steam for ACF regeneration was as small as 28 kg / h, and the desorption treatment was efficient.

[Example 13]
As shown in Table 2 and the following conditions, the same operation as in Example 1 was performed except that a gas to be treated containing 20000 ppm of acetone (boiling point 56.5 ° C.) was used as the organic solvent.

  As a result of this adsorption / desorption test, the concentration of acetone in the treated gas was as low as 50 ppm, and the amount of acetone discharged was as low as 24 g / h.

  Further, the amount of steam for ACF regeneration was as small as 28 kg / h, and the desorption treatment was efficient.

A, A ′ first adsorption tank B, B ′ second adsorption tank 2 blower 4 first adsorption tank introduction line 6, 6 ′, 26, 26 ′ ACF
8, 8 'First adsorption tank main body 10, 10', 30, 30 'Suction valve 12, 12', 32, 32 'Discharge valve 14, 14', 34, 34 'Steam valve 15, 15', 35, 35 'Steam injection means 16 First adsorption tank side steam introduction line 18 First adsorption tank side desorption gas valve 20 First adsorption tank side recovery line 22, 25, 25' Condenser 24 First adsorption tank processing gas transport line 28, 28 ' Second adsorption tank main body 36 Second adsorption tank side steam introduction line 38 Second adsorption tank side desorption gas valve 40 Second adsorption tank side recovery line 42 Second adsorption tank processing gas transport line

Claims (5)

A first adsorption tank filled with activated carbon fibers;
The second adsorption tank filled with activated carbon fibers that are the same as or different from the activated carbon fibers, wherein the mass (M ₂ ) of activated carbon fibers filled in the second adsorption tank is filled in the first adsorption tank. A second adsorption tank filled with activated carbon fibers of 0.05 to 0.25 in a mass ratio (M ₂ / M ₁ ) based on the mass (M ₁ ) of the carbon fibers;
A connecting pipe connecting the first adsorption tank and the second adsorption tank;
A condenser interposed in the connecting pipe;
Steam injection means provided in each of the first adsorption tank and the second adsorption tank;
An organic solvent removing apparatus having A method for removing an organic solvent in a gas to be treated using the organic solvent removing apparatus according to claim 1,
By supplying the gas to be treated containing 3000 ppm or more of the organic solvent to the first adsorption tank and adsorbing the organic solvent to the activated carbon fiber filled therein, and drying the condensed water contained in the activated carbon fiber, A first adsorption tank treatment gas containing 500 ppm or less of an organic solvent and moisture is obtained, and then this first adsorption tank treatment gas is supplied to a condenser to condense and separate the moisture in the first adsorption tank treatment gas to the outside of the system. While discharging, supplying the first adsorption tank processing gas from which the water has been separated to the second adsorption tank, the organic solvent contained in the first adsorption tank treatment gas is adsorbed to the activated carbon fibers filled in the second adsorption tank And an adsorption step of discharging the second adsorption tank treatment gas having an organic solvent concentration of 100 ppm or less to the outside by drying the moisture contained in the activated carbon fiber,
After the supply of the gas to be processed to be supplied to the first adsorption tank is stopped, steam is supplied into the first adsorption tank and the second adsorption tank by the steam injection means, and the first adsorption tank and the second adsorption tank are filled. By desorbing the adsorbed organic solvent of each activated carbon fiber, each activated carbon fiber adsorbing the organic solvent is regenerated to activated carbon fiber containing condensed water generated by condensation of the supplied steam. A desorption step of taking out the desorbed organic solvent out of the system;
The method of removing the organic solvent in the gas to be processed that repeats alternately. The activated carbon fiber filled in the first adsorption tank has an activity with a specific surface area of 1200 m ² / g or more and 2000 m ² / g or less, an average pore diameter of 1 to 4 nm, and a total pore volume of 0.2 to 0.8 cm ³ / g. The method for removing an organic solvent according to claim 2, wherein the organic solvent is carbon fiber. The activated carbon fiber filled in the second adsorption tank has a specific surface area of 600 m ² / g or more and less than 1400 m ² / g, an average pore diameter of 0.5 to ³ nm, and a total pore volume of 0.1 to 0.6 cm ³ / g. The method for removing an organic solvent according to claim 2, which is an activated carbon fiber. The method for removing an organic solvent according to claim 2, wherein the gas to be treated supplied to the first adsorption tank is a gas to be treated containing 5000 to 100,000 ppm of an organic solvent having a boiling point of 30 to 70 ° C.

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