JP2012040517A - Fixed bed type voc adsorption/desorption method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently cleaning an exhaust gas containing volatile organic compounds in a pollution control field.SOLUTION: The method includes arranging a plurality of small-diameter metallic adsorbing tubes 6 formed by filling a metallic small-diameter tube 9 with an adsorbent 5 in an adsorption tower 3, and causing VOC (volatile organic compound) in the exhaust gas to adsorb on an adsorbent by passing the exhaust gas through the plurality of small-diameter metallic adsorbing tubes to remove VOC. When the adsorption capacity of the adsorbent deteriorates after sufficiently adsorbing VOC, the small-diameter metallic adsorbing tube in which the adsorbent with adsorbed VOC is charged is heated by a heating medium to desorb VOC.

Description

  The present invention relates to a VOC fixed bed type adsorption / desorption method for purifying exhaust gas containing a volatile organic compound in the pollution prevention field.

  Volatile organic compounds (VOC) such as toluene, xylene, and trichlorethylene, which are considered as one of the causative substances of suspended particulate matter and photochemical oxidants, are discharged in the painting process, cleaning process, printing process, etc. The Air Pollution Control Law has been implemented to reduce VOC emissions, and measures to reduce VOC emissions such as recovery, regeneration, sealing, combustion / decomposition, and substance substitution are being implemented.

  The present invention is one of the VOC emission suppression measures described above, and is based on a fixed bed adsorption method using activated carbon or the like. As is well known, the fixed bed adsorption method using activated carbon recovers the VOC content from the exhaust gas, recycles it as a solvent, and reuses the exhaust gas as a fixed bed in which an adsorbent such as activated carbon is packed in the adsorption tower. The VOC flows into the adsorbent and is sufficiently adsorbed to remove it.

  If the adsorbent sufficiently adsorbs VOC, the adsorbing capacity decreases, so that it is necessary to desorb VOC or replace the adsorbent. Normally, steam is introduced, but the desorption gas generated at that time is introduced into the condenser together with a large amount of steam, and the VOC is cooled and recovered. For example, Japanese Patent Laid-Open Nos. 2001-149740 and 2001-179041 have been proposed.

  However, the agglomeration time due to the desorption of VOC takes 1 to 5 hours (first run) and the VOC residual rate of the adsorbent is 10 to 40%, and further, the moisture condensed from the steam and the recovered VOC Separation treatment was also necessary.

  The present invention has been made in view of the above points, and in order to solve the above-described problems, exhaust gas containing a volatile organic compound (VOC) is passed through an adsorption tower loaded with an adsorbent to exhaust gas. VOC fixed bed type adsorption / desorption method in which the VOC is adsorbed on the adsorbent and removed, and the VOC is sufficiently adsorbed on the adsorbent to reduce the adsorbent capacity. An adsorbent is loaded into a thin metal pipe and a plurality of fine metal adsorption cylinders formed in the shape of a narrow adsorption tower are arranged in the adsorption tower so that the exhaust gas containing VOC The VOC in the exhaust gas is adsorbed on the adsorbent and removed by passing it through a thin metal adsorption cylinder of the cylinder. When the adsorbent sufficiently adsorbs the VOC and the capacity of the adsorbent decreases, the VOC is adsorbed. Heat treatment with a heating medium on a small-diameter metal adsorption cylinder loaded with a suitable adsorbent To provide a VOC fixed bed adsorption and desorption wherein the desorbing wearing the VOC.

  In addition, after the VOC adsorbed by heat treatment with the heating medium is desorbed, the metal small diameter adsorption cylinder is cooled with the cooling medium, and the exhaust gas containing VOC is again recirculated into the metal fine diameter adsorption cylinder of the plurality of cylinders. The VOC fixed bed type adsorption / desorption method is characterized in that the VOC in the exhaust gas is adsorbed by the adsorbent and removed by passing through the sorbent.

  Furthermore, another object of the present invention is to provide a VOC fixed bed type adsorption / desorption method characterized in that a concentration sensor or / and a temperature sensor are arranged in at least one small-diameter adsorption cylinder.

  Furthermore, another object of the present invention is to provide a VOC fixed bed type adsorption / desorption method characterized in that when a metal small diameter adsorption cylinder is heated with a heating medium, the inside of the small diameter adsorption cylinder is in a reduced pressure state.

  In the present invention, an exhaust gas containing a volatile organic compound (VOC) is passed through an adsorption tower loaded with an adsorbent, and VOC in the exhaust gas is adsorbed on the adsorbent to remove the VOC. This is a VOC fixed bed adsorption / desorption method in which the adsorbent is heat-treated and the VOC is desorbed by adsorbing to the adsorbent when the adsorbent is heat treated. A plurality of fine metal adsorption cylinders formed in a tower shape are arranged in the adsorption tower, and exhaust gas containing VOC is allowed to pass through the metal fine adsorption cylinders of the plurality of cylinders so that VOC in the exhaust gas is adsorbent. By adsorbing to the metal, the metal small-diameter adsorption cylinders are gathered to form a fixed bed type adsorption tower, and the exhaust gas containing VOC is allowed to pass through the metal small-diameter adsorption cylinders to obtain VOCs. Can be removed by adsorbing to the adsorbent. Can.

  When the adsorbent sufficiently adsorbs the VOC and the capacity of the adsorbent decreases, the metal small-diameter adsorption cylinder loaded with the adsorbent adsorbing the VOC is heated with a heating medium to desorb the adsorbed VOC. Thus, for example, when the steam heating medium is fed into the adsorption tower, the steam heating medium uniformly contacts the entire outer peripheral surface of the metal small-diameter tube loaded with the adsorbent adsorbing the VOC and transfers heat. Then, the VOC adsorbed on the adsorbent in the metal small-diameter adsorption cylinder becomes a boiling state in a short time, evaporates, desorbs from the adsorbent, flows out from the metal small-diameter adsorption cylinder, and passes through the condenser. It can be recovered in a short time, and the remaining rate of VOC can be reduced to 5 to 10%, the recovery efficiency can be improved, and there is no need to separate the conventional steam heating medium from the condensed water. Can also be simplified

  In addition, after the VOC adsorbed by heat treatment with the heating medium is desorbed, the metal small diameter adsorption cylinder is cooled with the cooling medium, and the exhaust gas containing VOC is again recirculated into the metal fine diameter adsorption cylinder of the plurality of cylinders. The exhaust gas containing exhaust gas containing VOC can be efficiently and sequentially purified as described above by repeatedly performing the removal process by allowing the adsorbent to adsorb the VOC in the exhaust gas by passing the gas.

  Furthermore, by disposing a concentration sensor or / and a temperature sensor in at least one small-diameter adsorption cylinder, the concentration sensor can detect the concentration of VOC in the small-diameter adsorption cylinder. It is possible to detect that VOC is adsorbed in a saturated state by an adsorbent in a metal small-diameter adsorption cylinder, and can efficiently purify exhaust gas containing VOC, and a concentration sensor in the small-diameter adsorption cylinder or / And the temperature sensor can accurately control the supply and stop of the steam heating medium, and remove the VOC from the adsorbent adsorbed by heating the thin metal adsorption cylinder and removing it as much as possible. Can be recovered efficiently.

  Furthermore, when the metal small diameter adsorption cylinder is heated with a heating medium, the VOC adsorbed on the adsorbent in the metal small diameter adsorption cylinder can be shortened more efficiently by reducing the pressure inside the small diameter adsorption cylinder. It can be boiled in time, evaporated, desorbed from the adsorbent, flowed out of the metal small-diameter adsorption cylinder, and recovered in a short time through the condenser.

Schematic for explanation of the VOC adsorption treatment state of the exhaust gas of one embodiment of the present invention, Schematic for explanation of the VOC desorption processing state as above, An enlarged vertical sectional view for explanation (a) and an enlarged flat sectional view ((b)) of the thin-diameter adsorption cylinder part of the VOC adsorption / desorption process same as above.

  In the VOC fixed bed type adsorption / desorption method of the present invention, an exhaust gas containing a volatile organic compound (VOC) is passed through an adsorption tower loaded with an adsorbent, and the VOC in the exhaust gas is adsorbed on the adsorbent and removed. When the VOC is sufficiently adsorbed on the adsorbent and the capacity of the adsorbent decreases, the adsorbent is heat treated to desorb the VOC. A plurality of fine metal adsorption cylinders formed in the shape of a narrow adsorption tower are loaded in the adsorption tower so that exhaust gas containing VOC passes through the metal fine adsorption cylinders of the plurality of cylinders. When the VOC in the exhaust gas is adsorbed on the adsorbent and removed, and the adsorbent sufficiently adsorbs the VOC and the capacity of the adsorbent decreases, the metal small diameter adsorption cylinder loaded with the adsorbent adsorbing the VOC Heat treatment with a heating medium to desorb the adsorbed VOC It is a symptom.

  As shown in FIGS. 1 and 2, the VOC fixed bed type adsorption / desorption device 1 is a fixed bed type exhaust gas containing a volatile organic compound (VOC) such as toluene, xylene, trichlorethylene or the like through an inflow pipe 2 having a predetermined diameter. The small-sized adsorption towers 6 are loaded into the adsorption tower 3 so that the small-sized adsorption towers are gathered, and the small-sized adsorption towers 6 are gathered. In this way, it is made to pass through each of these small-diameter adsorption cylinders 6, purify the VOC in the exhaust gas by adsorbing it to the adsorbent 5, and flow out from the outlet 7 through the outflow pipe 8. ing.

  As shown in FIG. 3, the small diameter adsorbing cylinder 6 is formed by loading a metal thin tube 9 with an adsorbent 5 to form a small diameter adsorption tower. Steel pipes, alloy steel pipes, stainless steel (SUS) steel pipes, and metal pipes such as titanium can be used, and stainless steel (SUS) steel pipes having corrosion resistance, durability, and availability are preferable. The diameter is 10 to 100 mm, preferably 10 to 50 mm, more preferably 10 to 30 mm, and the diameter, number, and length can be appropriately determined according to the treatment capacity of the adsorption tower 3. , Can be arranged in a lattice or staggered pattern. Note that the thin tube 9 is preferably as thin as possible, and the adsorbent 5 can be loaded and held by attaching a metal mesh 10 of a predetermined mesh to the bottom.

  Further, as the adsorbent 5, granular, bead-like, fibrous, honeycomb-like activated carbon, zeolite, or the like can be used, and those having a shape and size that can be easily loaded into the small-diameter tube 9 and can be exchanged are preferable. Those having a diameter corresponding to a diameter of 2 to 10 mm, particularly those corresponding to a diameter of 3 to 6 mm are preferable.

  1 to 3, the upper and lower end portions thereof are perpendicular to the partition plates 11 and 12, and the metal thin-diameter adsorption cylinders 6 are penetrated to form a plurality of metal thin-diameter adsorption cylinders 6 respectively. The upper and lower portions are hermetically disposed on the partition plates 11 and 12, and the upper and lower partition plates 11 and 12 are hermetically disposed at substantially the center of the adsorption tower 3, so that the exhaust gas containing VOC The VOCs in the exhaust gas are adsorbed and removed by the adsorbents 5 that are loaded by passing through the thin metal adsorption cylinders 6 of the cylinder.

  Then, a heating medium such as steam is connected between upper and lower partition plates 11 and 12 in which a plurality of thin metal adsorption cylinders 6 of the adsorption tower 3 are hermetically arranged, and the adsorbent 5 is connected. When VOC is sufficiently adsorbed and the capacity of the adsorbent 5 is reduced, the concentration of VOC is measured by the semiconductor type concentration sensors 13 and 14 disposed in the outflow pipe 8 of the small diameter adsorption cylinder 6 and the adsorption tower 3. When a predetermined concentration is obtained as detected, a heating medium such as steam is supplied so that the entire surface of the outer peripheral surface is uniformly heated over the upper and lower lengths of the thin metal adsorption cylinder 6. Is formed. As the heating medium, steam is preferable because of its large heating capacity. Reference numerals 15 and 16 denote temperature sensors, which are appropriately disposed in the small-diameter adsorption cylinder 6 and the adsorption tower 3, respectively, so as to detect the temperature of these portions, and temperature control management of a heating medium such as steam. And safety control management.

As shown in FIGS. 1 and 2, open / close valves 17 and 18 are provided at the upper and lower inlets 4 and 7 of the adsorption tower 3, respectively. When heating medium such as steam is supplied, these valves are opened and closed. The valves 17 and 18 are closed, and a heating medium such as steam of 0.3 to 1 Pa (3 to 10 Kg / cm ² ) and 100 to 180 ° C. is supplied from the heating medium supply port 19 on the side of the adsorption tower 3. ing. The steam is preferably superheated steam, and can be obtained by heating steam generated by a boiler or the like with an electric heater heating device or the like of a sheathed heater. 20 is a heating medium outlet, 21 is a drain outlet, 22 is a condensing device, 23 is a vacuum pump, 24 is a recovery can, and a concentration sensor S is provided in the VOC outlet 25 of the adsorption tower 3, and each supply An automatic opening / closing valve or the like can be disposed on the opening, the discharging portion, etc. so as to be freely controlled.

  When the VOC adsorbed by heat treatment with the heating medium is desorbed in this manner, the concentration sensor 13 and S disposed at the VOC discharge port 25 of the small diameter adsorption cylinder 6 and the adsorption tower 3 detect the concentration of VOC to be predetermined. When the cooling medium is cooled, the cooling medium such as water or air is introduced by diverting the heating medium supply port 19 on the side of the adsorption tower 3 and cooling is completed. The removal treatment can be repeated by passing the exhaust gas containing VOC through the metal small-diameter adsorption cylinder 6 to adsorb the VOC in the exhaust gas to the adsorbent 5. If necessary, it can also be performed by timer setting.

  In the above description, the gist of the present invention has been described with one adsorption tower 3 as a unit. However, according to the gist of the present invention, an appropriate number of adsorption towers 3 are arranged in parallel according to the processing amount of exhaust gas. In other words, it is possible to implement an embodiment corresponding to the above.

  FIG. 1 and subsequent figures show an embodiment of the present invention. As shown in FIG. 1, the VOC fixed bed type adsorption / desorption device 1 flows exhaust gas containing a volatile organic compound (VOC) from an inlet 4 of a fixed bed type adsorption tower 3 through an inflow pipe 2 having a predetermined diameter. Then, adsorbent 5 of granular activated carbon corresponding to a diameter of 3 to 8 mm is loaded into a small diameter pipe 9 of a stainless steel (SUS) pipe having a diameter of 30 mm, and a small diameter adsorption cylinder 6 is assembled into an adsorption tower shape. Then, the VOC in the exhaust gas is adsorbed on the adsorbent 5 for purification, and flows out from the outlet 7 through the outflow pipe 8.

  Such a metal small diameter adsorption cylinder 6 has a length of about 50 cm, and upper and lower ends thereof are staggered on partition plates 11 and 12 of stainless steel (SUS) plates having a predetermined thickness as shown in FIGS. The upper and lower portions of a stainless steel (SUS) small-diameter pipe 9 are hermetically welded to the partition plates 11 and 12, respectively, and the upper and lower partition plates 11 and 12 are hermetically arranged in the adsorption tower 3. The VOC contained in the exhaust gas is adsorbed to the adsorbent 5 loaded by passing the exhaust gas containing VOC through the small diameter adsorption cylinders 6 of the metal and removed.

  The steam heating medium can be supplied freely from the heating medium supply port 19 on the side between the upper and lower partition plates 11 and 12 in which the plurality of metal thin-diameter adsorption cylinders 6 of the adsorption tower 3 are hermetically disposed. In addition to pipe connection, required concentration sensors 13, 14, and S for semiconductors are disposed in at least one small-diameter adsorption cylinder 6, the outflow pipe 8 at the outlet 7 of the adsorption tower 3, and the VOC outlet 25. The VOC concentration is detected, and the temperature sensors 15 and 16 are disposed in the small-diameter adsorption cylinder 6 and the adsorption tower 3 to detect the temperatures of these parts, so that the exhaust gas is supplied. , Stop control, temperature control management of steam heating medium and safety control management are made possible.

  As shown in FIG. 1, when exhaust gas containing VOC flows into the adsorption tower 3 formed in this way through the blower through exhaust gas containing VOC from the upper inlet 4, the exhaust gas is a plurality of metal small-diameter adsorption cylinders. The VOC in the exhaust gas passes through the inside of the exhaust gas 6 and is adsorbed and removed by the adsorbent 5 and flows out from the outlet 7 so that the exhaust gas can be purified.

When the adsorbent 5 sufficiently adsorbs VOC and the capability of the adsorbent 5 is reduced by the concentration sensors 13 and 14 in the small diameter adsorbing cylinder 6 and the outlet 7 part of the adsorbing tower 3, respectively, the adsorbing tower The upper and lower inlet 4 parts and the outlet 7 parts of the on-off valves 11 and 12 are closed, and the heating medium supply port 13 on the side of the adsorption tower 3 is heated to 0.3 Pa (3 Kg / cm ² ), 130 ° C. superheated steam. Supply media.

  When the steam heating medium is fed into the adsorption tower 3, the outer peripheral surface of the metal small-diameter adsorption cylinder 6 loaded with the adsorbent 5 having adsorbed VOC is heated with steam. As shown in FIGS. 3 (a) and 3 (b), the steam heating medium uniformly contacts the entire outer peripheral surface of the metal thin-diameter adsorption cylinder 6 and transfers heat to the inside. The adsorbent 5 adsorbed VOC is boiled instantaneously or in a short time, evaporates, desorbs from the adsorbent 5, flows out of the metal small-diameter adsorption cylinder 6, and the condenser device 22 is discharged from the VOC discharge port 25. And can be recovered in the recovery can 24 in a short time. The residual rate of VOC is as low as 5 to 10%, and there is no need to separate the conventional steam heating medium from the condensed water, improving the quality accuracy of the recovered product, saving space and simplifying the equipment. it can.

  When the VOC adsorbed by heat treatment with steam is desorbed and detected by the concentration sensors 13 and S in the VOC discharge port 25 in the small diameter adsorption cylinder 6 and the adsorption tower 3, the desorption state of the VOC is confirmed. 13 is switched to an air cooling medium to flow in, the outer peripheral surface of the metal small diameter adsorption cylinder 6 is cooled with the cooling medium, and the exhaust gas containing VOC flows again into the adsorption tower 3 to enter the small diameter adsorption cylinder 6. The inside of the exhaust gas is passed through, and the VOC in the exhaust gas is adsorbed by the adsorbent 5 and removed repeatedly. In this way, purification treatment of exhaust gas containing VOC can be carried out efficiently and sequentially.

  By making the metal small diameter adsorption cylinder 6 small, when the steam heating medium is fed into the adsorption tower 3 as shown in FIGS. 3 (a) and 3 (b), the steam heating medium is VOC. The VOC adsorbed to the adsorbent 5 in the metal small-diameter adsorption cylinder 6 is instantaneously brought into contact with the entire outer peripheral surface of the metal small-diameter adsorption cylinder 6 loaded with the adsorbent 5 adsorbed to transfer heat. Or it becomes a boiling state in a short time, evaporates, desorbs from the adsorbent, flows out from the metal small diameter adsorption cylinder 6, sucks through the vacuum pump 23, and condenses in the condensing device 22. It can be recovered well. In heating the steam, steam generated by a boiler or the like is heated by an electric heater heating device of a sheathed heater or the like, and high-temperature superheated steam of about 150 ° C. is preferable. VOC is absorbed more quickly from the adsorbent 5 that has adsorbed VOC. Can be desorbed.

  In addition, by making the inside of the small diameter adsorption cylinder 6 in a reduced pressure state with the vacuum pump 23, the VOC adsorbed on the adsorbent 5 in the metal small diameter adsorption cylinder 6 is more efficiently evaporated as a boiling state in a short time, It can be desorbed from the adsorbent 5 and allowed to flow out of the metal small diameter adsorbing cylinder 6 and can be recovered in a shorter time.

  Thus, in the past, it took 1 to 5 hours to recover VOC, but it can be processed in a short time such as several minutes to several tens of minutes, and exhaust gas removal processing can be performed efficiently in a short time. Can do.

  INDUSTRIAL APPLICABILITY The present invention can widely use exhaust gas containing a volatile organic compound generated in a painting process, a cleaning process, a printing process, etc. in the purification treatment field.

DESCRIPTION OF SYMBOLS 1 ... Adsorption / desorption apparatus 3 ... Adsorption tower 5 ... Adsorbent 6 ... Thin diameter adsorption cylinder 9 ... Thin diameter pipe 11, 12 ... Partition plate 13 ... Concentration sensor 15 ... Temperature sensor 19 ... Heating medium inflow port

JP 2001-149740 A JP 2001-179041 A

Claims (4)

The exhaust gas containing the volatile organic compound (VOC) is passed through the adsorption tower loaded with the adsorbent, and the VOC in the exhaust gas is adsorbed on the adsorbent to be removed, and the VOC is sufficiently adsorbed on the adsorbent. When the capacity of the adsorbent is reduced, a VOC fixed bed type adsorption / desorption method in which the adsorbent is heated to desorb VOC,
A plurality of fine metal adsorption cylinders formed into a thin adsorption tower by loading an adsorbent into a thin metal pipe are disposed in the adsorption tower, and exhaust gas containing VOC is exhausted from the metal of the multiple cylinders. When the VOC in the exhaust gas is adsorbed on the adsorbent and removed by passing through the small-diameter adsorption cylinder, and the adsorbent sufficiently adsorbs the VOC and the capacity of the adsorbent decreases, the adsorbent adsorbing the VOC is removed. A VOC fixed bed type adsorption / desorption method, characterized in that the adsorbed VOC is desorbed by heat-treating a loaded metal small-diameter adsorption cylinder with a heating medium. After the VOC adsorbed by heat treatment with the heating medium is desorbed, the metal small-diameter adsorption cylinder is cooled with the cooling medium, and the exhaust gas containing VOC again passes through the multiple metal fine-diameter adsorption cylinders. The VOC fixed bed type adsorption / desorption method according to claim 1, wherein the VOC in the exhaust gas is repeatedly adsorbed by the adsorbent and removed. The VOC fixed bed type adsorption / desorption method according to claim 1 or 2, wherein a concentration sensor or / and a temperature sensor are disposed in at least one small-diameter adsorption cylinder. The VOC fixed bed type adsorption / desorption method according to any one of claims 1 to 3, wherein when the metal small-diameter adsorption cylinder is heated with a heating medium, the inside of the small-diameter adsorption cylinder is depressurized.

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