JPH07265641A - Solvent recovery device - Google Patents

Abstract

PURPOSE:To obtain a solvent recovery device dispersing with a waste liq. mixture treating device, capable of miniaturizing a device for burning the waste at need, and capable of remarkably reducing the running cost. CONSTITUTION:A steam generator 5 is provided below a solvent adsorption tower 1, a condenser 10 is furnished to the tower, and a distillation column 18 is connected to the condenser. A gas contg. a water-soluble solvent vapor is introduced into the tower 1 from the upper part to adsorb the solvent vapor, and steam is blown in from the generator 5 to desorb the adsorbed solvent. A pipeline 19 to supply the water separated from the column 18 to the generator 5, a separated water tank 20, a pipeline 21 and a makeup water pipe 23 are further provided.

Description

Detailed Description of the Invention

[0001]

This invention relates to printing, paint, resin,
Exhaust gas (organic solvent) generated from the solvent vapor generation part in the cleaning industry, etc., especially methyl alcohol, which is soluble in water,
I. P. The present invention relates to an apparatus suitable for recovering a solvent such as A, toluene, ethyl acetate, butyl acetate, and acetone.

[0002]

2. Description of the Related Art As a conventional solvent recovery device of this type, there is an adsorption tower type solvent recovery device.

[0003]

By the way, in this conventional apparatus, in order to discharge the water containing the solvent recovered in the adsorption tower, that is, the mixed liquid (condensed liquid) to the outside of the system (river), this liquid is discharged. It must be treated below the regulation value according to the wastewater standards. Therefore, a wastewater treatment device for the liquid is required.
Further, since the amount of water contained in the liquid is large, the equipment becomes a large facility and the operating cost is high. Further, there is also a method in which the mixed liquid is burned by a combustion device, but in this case as well, there is a problem that the equipment is large and the operating cost is increased as in the above case.

Therefore, the present invention solves the above-mentioned conventional problems, does not require a wastewater treatment apparatus for mixed liquids, and can reduce the size of the apparatus for combustion treatment and the operating cost. It is an object of the present invention to provide a solvent recovery device that can be manufactured at a significantly low cost.

[0005]

In order to achieve the above object, a solvent recovery apparatus of the present invention is provided with a vapor generator below a solvent adsorption tower, a condenser provided in the adsorption tower, and a condenser. In a solvent recovery device that installs a distillation column connected to, adsorbs solvent vapor by introducing gas containing water-soluble solvent vapor from above into the adsorption column, and desorbs the adsorbed solvent by blowing vapor from the vapor generator. A pipe is provided to supply the separated water from the distillation column to the steam generator. The steam generator is composed of an overheating electric heating coil and a steam generating electric heating coil arranged above and below. In this case, a heating pipe for overheating may be provided instead of the heating coil for overheating, and a heating pipe for steam generation may be provided instead of the heating coil for steam generation.

Further, the solvent recovery apparatus of the present invention comprises two solvent adsorption towers and a condenser provided in each of these adsorption towers or as a common one, and a common steam generator is provided. Provided in connection with the lower part of each of the adsorption towers, provided with a shared distillation column connected to the condenser, a pipe for supplying separated water from the distillation column to the steam generator, one of the adsorption towers When the concentration of the solvent exhausted from the outlet of the first adsorption tower exceeds a predetermined value, the operation of the one adsorption tower is stopped and the operation of the other adsorption tower is started.

[0007]

[Function] The condensate containing the water-soluble solvent is sent to the distillation column,
Due to the difference in the boiling points, the solvent is evaporated and divided into concentrated solvent and water. The separated water is supplied to the steam generator again through the pipe. Although a small amount of solvent is also contained in the supplied separated water, it is sent to the adsorption tower together with the steam by heating by the steam generator to be desorbed and is not discharged to the outside of the system. Further, even if the separated water is circulated in this way, the solvent itself evaporates, so that the solvent does not increase in the steam generator.

[0008]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention. Reference numeral 1 denotes an adsorption tower, which is installed on the leg portion 2 by accommodating the adsorbent a of the activated carbon tower therein. 3 is a dust filter, 4 is a fan connected to the dust filter 3, and this fan 4 is installed in communication with the upper space of the adsorbent a accommodated in the adsorption tower 1.

Reference numeral 5 denotes a steam generator directly connected to the lower part of the adsorption tower 1. The steam generator 5 has a housing 6, and an upper heating electrothermal coil 7 is provided in the upper space of the housing 6. An electric heating coil 8 for steam generation is arranged in the water.

A condenser 10 composed of an inner and outer double pipe is wound around the upper periphery of the adsorption tower 1. The inner tube of the condenser 10 is provided with an inlet 11 for supplying cooling water and an outlet 12 for discharging water. One end of the outer pipe is connected to an introduction pipe 13 opened in the upper space of the adsorbent a housed in the adsorption tower 1, and the other end is a drain pipe.
It is connected via 14 to a condensate temporary storage tank 15. A distillation column 18 is connected to the tank 15 via a pump 16 and a pipe 17, and a separation water tank 20 is connected to the distillation column 18 via a pipe 19. The lower part of the separation water tank 20 is connected to a makeup water pipe 23 via a pipe 21 having a valve 22. The makeup water pipe 23 is connected to the casing 6 of the steam generator 5. 18
Reference numerals a, 18b and 18c are a heater attached to the distillation column 18 for generating steam and the like, a cooler for cooling the solvent, and a water sealing portion for separated water.

Reference numeral 25 is a gas introducing damper, 26 is an air exhausting damper, and 27 and 28 are temperature controllers. The temperature controller 27 has a steam generating electrothermal coil 8 which is always underwater exposed on the water surface in case of an accident. The temperature controller 28 is provided so as to switch off the coil when the power is turned on while the coil is turned on or off when the heating coil 7 for overheating becomes below or above the set temperature. Has been. 30 is the case 6
A water level gauge for maintaining the water level in the inside at a constant water level, 31 is a solenoid valve, 32 is an exhaust pipe, and 33 is a solvent extraction pipe.

The operation of the above embodiment will be described. Damper 25,
26 is opened, and the raw gas containing the water-soluble solvent vapor is introduced into the dust filter 3 by the activation of the fan 4. This raw gas is supplied with static air pressure by the fan 4 and is supplied into the adsorption tower 1 for adsorption. The solvent vapor in the gas is adsorbed by the adsorbent a while passing through the agent a, and the air purified by this is exhaust pipe.
It is released into the atmosphere via 32.

After the adsorbent a has adsorbed a predetermined amount, the dampers 25 and 26 are closed, and the steam generated in the casing 6 of the steam generator 5 is sent to the adsorbent a, whereby the adsorbent a is adsorbed. The used solvent is desorbed.

The desorbed solvent vapor and water vapor are introduced into the introduction pipe 13
Is led to the condenser 10 through the passage and is condensed while passing countercurrently with the cooling water through the passage in the outer pipe forming the condenser, becomes liquid and is temporarily stored in the tank 15 through the drain pipe 14. . At this time, cooling water flows in through the inlet 11 to cool the solvent vapor and water vapor, and is discharged through the outlet 12.

The mixed liquid (condensed liquid) in the tank 15 is pump 16
The distillation column 18 is continuously activated by a fixed amount via the pipe 17 when the
And is heated by the steam from the heater 18a to evaporate the solvent due to the difference in boiling point and separated into concentrated solvent and water. The solvent evaporated in the distillation column 18 is cooled by the cooler 18
The separated water cooled by b, recovered from the conduit 33, and separated is separated into a separated water tank 20 through a water sealing portion 18c and a pipe 19.
After entering, it is supplied into the casing 6 of the steam generator 5 through the pipe 21 and the makeup water pipe 23. The recovered concentrated solvent is reused or used as a combustion improver. Further, it is burned depending on its component and concentration. It should be noted that even a small amount of solvent (preferably even if containing about 1% or less) in the separated water is sent to the adsorption tower 1 together with the steam by heating by the steam generator 5 to be desorbed and discharged to the outside of the system. There is no. Even if the separated water is circulated in this way, the solvent itself evaporates,
There is no increase in solvent.

When the desorption is completed, the dampers 25 and 26 are opened, the fan 4 is activated and the cooling gas (generally the atmosphere) is introduced, and the adsorbent a is dried and cooled.

2 to 3 show an adsorption tower 1 having the same structure as described above.
2 units are installed in parallel, and the distillation column 18 and the steam generator 51 are installed.
1 shows an example in which one is installed as a common one in these adsorption towers. That is, the distillation column 18 is connected to the condensers 10 of the No. 1 adsorption column 1 and No. 2 adsorption column 1 by the pipes 53 and 54, the tank 15, the pump 16 and the pipe 17. It should be noted that each condenser 10 may be independent of each adsorption tower 1 and one may be shared by each adsorption tower. Also, the steam generator 51
Are connected to the lower portions of the No. 1 adsorption tower 1 and No. 2 adsorption tower 1 by pipes 56 and 57, and a three-way valve 58 is installed at the connecting portion of the pipes 56 and 57. Reference numeral 60 denotes a separated water tank, which includes a distillation tower 18 and a pipe 61 having a water sealing portion 18c, and a steam generator 51 and a pipe 62.
Are respectively connected via. Reference numeral 64 denotes a pump installed in the pipe 62, and 65 in the steam generator 51 denotes a steam generation chamber, in which a steam superheating coil 66 as an electric heater is provided.
And a heating coil 67 for steam generation are arranged above and below. 68
Is a liquid level gauge (controller), 70 is a blanking prevention thermometer, and 71 is an overheat prevention thermometer.

Reference numeral 73 is a pipe 74 having a distillation column 18 and a cooler 18b.
Solvent recovery tanks connected through, 76 and 77 are exhaust pipes connected to the exhaust pipes 32 of the No. 1 adsorption tower 1 and No. 2 adsorption tower 1, and 78 is a cooling water supply pipe. Valve near tower 1
80 and 81 are provided. 83 is a cooling water return pipe, 90, 91
Is a drain pipe that connects the separated water tank 60 and the exhaust pipe 32 of the No. 1 adsorption tower 1 and the No. 2 adsorption tower 1. No. 1 adsorption tower 1
The operation of the No. 2 adsorption tower 1 and stop of the No. 2 adsorption tower 1 can be alternately switched by a control member (not shown).

An example of the operation of this example will be described below. In this example, the raw gas containing the water-soluble solvent is supplied into the No. 1 adsorption tower 1 through the duct filter (not shown) when the dampers 25, 26 of the No. 1 adsorption tower 1 are opened and the fan 4 is started. Only the solvent is adsorbed by the adsorbent a in the adsorption tower 1, and the cleaned air is discharged into the atmosphere through the exhaust pipes 32 and 76. Then, when the adsorption time in the No. 1 adsorption tower 1 becomes long, the amount of the solvent in the adsorbent a increases, and the solvent is gradually exhausted from the outlet of the adsorption tower a. The breakthrough point is the concentration of about 10% of the concentration. Before this breakthrough time, the control member was No. 1 adsorption tower 1
Then, the operation is switched to the No. 2 adsorption tower 1. 1
In order to desorb the solvent from the adsorbent a when the adsorption by the adsorption tower 1 is completed, the steam generator 51 is connected to the pipe 56 and the three-way valve 58.
After that, steam (105 ° C. to 110 ° C.) is sent to the No. 1 adsorption tower 1. The steam and the solvent desorbed by the steam are cooled in the condenser 10 and liquefied. The liquefied mixed liquid (solvent and water) is temporarily stored in the tank 15 via the pipe 53. Next, when the pump 16 is started, it is sent to the distillation column 18 through the pipe 17, where the mixed liquid is heated by the steam from the heater 18a, the solvent is evaporated due to the difference in boiling point, and the concentrated solvent and water are separated. It Then, the solvent is cooled by the cooler 18b and is recovered in the recovery tank 73 through the pipe 74 and is reused or used as a combustion improver. Further, it is burned depending on its component and concentration. On the other hand, the separated water is the water sealing part 18c,
It is sent to the separated water tank 60 via the pipe 61. This separated water contains a small amount of dissolved solvent.

The separated water in the separated water tank 60 is supplied to the steam generator 51 by the pump 64 through the pipe 62. Steam generator 51
Then, the separated water is evaporated by the steam generating heating coil 67 provided in the steam generating chamber 65 to generate superheated steam (105 ° C to 110 ° C). A small amount of solvent is also heated in the steam generation chamber 65, and is sent to the No. 1 adsorption tower together with water vapor for desorption.
When steam is generated in the steam generation chamber 65 and the liquid level is lowered, the pump 64 is activated by the liquid level gauge 68 to replenish the separated water in the separated water tank 60. If the separated water is insufficient, replenish industrial water as supplementary water. Incidentally, since a trace amount of residual solvent contained in the separated water is also heated and vaporized by the steam generator 51,
The solubility is always constant, and even if the separated water is circulated, the solvent of the separated water does not increase.

FIG. 4 shows another example of the steam generator. This steam generator 85 is equipped with steam superheat pipes at the top and bottom of the steam generation chamber 87.
88 and a steam generation pipe 89 are provided, and steam is supplied to the both pipes from a steam generator boiler 86 through a conduit. Then, the separated water is vaporized by the steam heating pipe 88 and the steam generating heating pipe 89. Such a steam generator 85 may be installed in place of the steam generator 5 provided in the lower part of the adsorption tower 1 in FIG. The same effect can be obtained by replacing the distillation column 18 with a rectification column.

[0022]

Since the inventions of claims 1 to 3 have the above-mentioned constitutions, they have the following excellent effects. (1) The separated water is supplied to the steam generator, heated, and circulated as water vapor, which eliminates the need for a wastewater treatment device for draining the collected mixed solution of solvent and water, thereby reducing the equipment cost. It can be greatly reduced. Also, when the concentrated solvent is incinerated, the amount becomes 1/4 to 1/10 of the mixed liquid, and the equipment cost and the operating cost can be greatly reduced. (2) Since a small amount of solvent remaining in the separated water is also heated by the steam generator, it is vaporized (solvent vapor) and circulated together with water vapor. Therefore, the solubility of the solvent remaining in the separated water is always constant and does not increase. Therefore, the separated water can be continuously circulated (that is, continuous desorption operation can be performed), and the steam generator and the piping are less corroded. (3) Since the separated water is converted into steam by the steam generator, severe temperature control is not required and the operation becomes easy. (4) The structure is relatively simple and can be manufactured at low cost. In addition to the above, the invention of claim 4 can further perform adsorption treatment by alternate operation of two adsorption towers, thereby increasing the operation rate.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention.

FIG. 2 is a piping system diagram showing an example in which two adsorption towers are installed in parallel.

FIG. 3 is an enlarged view of a main part of FIG.

FIG. 4 is an enlarged view of an essential part showing another example of the steam generator corresponding to FIG.

[Explanation of symbols]

 1 Adsorption tower 3 Dust filter 4 Fan 5 Steam generator 7 Electric heating coil for overheating 8 Electric heating coil for steam generation 10 Condenser 17, 21 Piping 18 Distillation tower 20 Separation water tank 23 Make-up water pipe

Claims (4)

[Claims] 1. A steam generator is provided below a solvent adsorption tower,
And a condenser is provided in the adsorption tower, a distillation tower connected to the condenser is provided, and a gas containing a water-soluble solvent vapor is introduced into the adsorption tower from above to adsorb the solvent vapor,
A solvent recovery apparatus for desorbing adsorbed solvent by injecting steam from the steam generator, characterized in that a pipe for supplying separated water from the distillation column to the steam generator is provided. 2. The steam generator comprises a superheating electric heating coil and a steam generating electric heating coil which are arranged one above the other.
The solvent recovery device described. 3. The solvent recovery apparatus according to claim 2, wherein a heating pipe for overheating is provided in place of the heating coil for overheating, and a heating pipe for steam generation is provided in place of the heating coil for steam generation. 4. A solvent vapor adsorption tower comprising two solvent adsorption towers and a condenser provided in each of these adsorption towers or provided as a common one, and a common steam generator is connected to a lower portion of each of the adsorption towers. A common distillation column is connected to the condenser, and a pipe for supplying separated water from the distillation column to the steam generator is provided, and the solvent exhausted from one outlet of the adsorption column is provided. When the concentration exceeds a predetermined value, the operation can be switched so that the operation of the one adsorption tower is stopped and the operation of the other adsorption tower is started.