JP2008043920A - Organic matter-containing gas treatment facility and its treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic matter-containing gas treatment facility which can significantly reduce a moisture content (dissolved) to such an extent that no bleeding hardly occurs, even in the case where a hydrophilic organic matter-containing gas is recovered and the organic matter is recycled for a printing ink, and meantime, enables efficient adsorption/desorption of the gas containing a low concentration and yet a large amount of the organic matter to achieve an efficient recovery of the organic matter, and can certainly eliminate explosion risks, and an organic matter-containing gas treatment method. <P>SOLUTION: The organic matter-containing gas treatment facility comprises the following components: a dehumidification mechanism 2 which removes a moisture content of the gas to be treated containing the organic matter, an active carbon adsorber 4 which is fitted and filled with a honeycomb-shape active carbon for adsorbing/removing the organic matter contained in the dehumidified treated gas, heated gas feeders 6, 7 and 12 which feed an inert gas heated to desorb the organic matter adsorbed by the active carbon adsorber 4 from the active carbon, coolers 13 and 14 which dehydrate the organic matter desorbed by the heated inert gas by refrigerating the organic matter to 0°C or below, and a recovery device 15 which recovers the dehydrated organic matter. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic substance-containing gas treatment facility and a treatment method thereof, and more particularly to an organic matter-containing gas treatment equipment and treatment method for treating a gas mainly containing a hydrophilic organic substance in a low concentration and a large amount.

  Conventionally, in order to treat a gas containing organic solvent, VOC (volatile organic compound) and other organic compounds, it is passed through a filling tank filled with granular activated carbon to adsorb organic matter on granular activated carbon, and then a large amount There is known a method of collecting and incinerating organic substances by heating and desorbing them by passing water vapor. However, the method of adsorbing to the granular activated carbon is that the linear flow rate of the gas is 10 to 30 cm / second, the filling height of the granular activated carbon is about 100 to 300 cm, the opening ratio of the granular activated carbon is low, and the ventilation resistance is large. There is a problem that the contact efficiency of the flowing gas is low.

  In other words, if the activated carbon is granular, unevenness in the gas flow is likely to occur, and due to uneven adsorption, local heat is generated inside the packed bed, the adsorption performance decreases, and organic substances adsorbed on the activated carbon begin to desorb. There is also a risk of heat generation. In addition, when a heated gas containing oxygen such as heated air is passed to desorb the adsorbed organic matter, local heat generation occurs, the organic matter may ignite, and the granular activated carbon may burn. In addition, there is a problem in that fine powder is generated from the granular activated carbon during repeated use, clogging is likely to occur, and the airflow resistance may increase rapidly.

  A method of using fibrous activated carbon instead of granular activated carbon has been considered (for example, Patent Document 1). This method also has a problem that the ventilation resistance is large, clogging is likely to occur due to dust in the processing gas, it cannot withstand long-term use, frequent maintenance and inspection are required, and workability is inferior.

  As a method for reducing the ventilation resistance, a method using honeycomb-like activated carbon is also considered (for example, Patent Document 2).

  The above-described conventional method using the honeycomb-like activated carbon is said to explode depending on the organic matter when it reaches the explosion limit when hot air is fed to dry after passing water vapor to collect the adsorbed organic matter. Since there is a problem, the present inventors have invented an organic substance-containing gas treatment facility and a treatment method for solving the problem (Patent Document 3).

JP 11-239723 A JP-A-10-216477 JP 2006-88102 A

  However, when this organic substance-containing gas processing facility is used in a printing factory or the like to recover and reuse the organic solvent in the exhaust gas, the following problems arise. That is, instead of non-hydrophilic solvents such as toluene, hydrophilic organic solvents with lower toxicity (for example, ethyl acetate, methyl ethyl ketone, etc.) are often used as organic solvents. When this organic solvent is used for printing ink because it contains a certain amount of moisture, ink bleeding occurs on the printing surface. However, the moisture contained in the organic solvent recovered by the conventional treatment equipment is also affected by the relative humidity in the atmosphere, and even when the relative humidity is low, the dissolved moisture contained in the organic solvent is 1.5 weight. %, Usually about 2 to 3% by weight.

  Therefore, in view of the above-mentioned problems of the prior art, the object of the present invention is to recover gas containing a hydrophilic organic substance, and to contain the organic substance so that bleeding does not easily occur even when the organic substance is reused for printing ink (dissolved). ) Organic substances that can greatly reduce the amount of water, yet effectively adsorb and desorb gases containing low concentrations and large quantities of organic substances, efficiently recovering organic substances, and reliably preventing the risk of explosion It is to provide a contained gas treatment facility and a treatment method thereof.

  The above objects can be achieved by the inventions described in the claims. That is, the characteristic configuration of the organic substance-containing gas processing facility according to the present invention includes a dehumidifying mechanism that removes moisture contained in the gas to be treated containing organic substances, and an organic substance in the dehumidified gas to be adsorbed and removed. Activated carbon adsorbing device filled with and loaded with honeycomb-like activated carbon, heated gas supply device for supplying heated inert gas to desorb organic matter adsorbed by the activated carbon adsorbing device from the activated carbon, and the heated The object of the present invention is to have a cooling device that cools and dehydrates the organic matter desorbed by the inert gas to a temperature below zero degree, and a recovery device that collects the dehydrated organic matter.

  According to this configuration, before the organic substance in the gas to be treated is adsorbed / removed by the activated carbon adsorption device, the moisture is reduced in advance by the dehumidifying mechanism and the organic substance desorbed by the inert gas is cooled to below zero degree. The dehydrating cooling device can remove the moisture in the organic matter contained in the inert gas, so the moisture in the collected organic matter can be reduced sufficiently, even if the gas containing hydrophilic organic matter is collected and printed. Even when reused in ink, the amount of contained (dissolved) water can be reliably reduced to such a degree that bleeding is unlikely to occur. Moreover, since the activated carbon adsorption device uses honeycomb-like activated carbon, the ventilation resistance can be reduced and the adsorption rate is high, so it is efficient even when processing a large amount of gas at a low concentration. Since the inert gas is allowed to flow to desorb the adsorbed organic matter, it is possible not only to prevent ignition of the desorbed organic matter, but also to prevent explosion reliably and to easily collect the organic matter. Therefore, large-scale facilities such as a distillation tower are not required. Of course, since nitrogen is used for desorption of organic substances, there is an advantage that water treatment is not necessary as compared with the case of using water vapor as in the prior art.

  As a result, gas containing hydrophilic organic substances can be recovered and the water content can be greatly reduced to such an extent that bleeding is unlikely to occur even when the organic substances are reused in printing ink, yet a gas containing a low concentration and a large amount of organic substances. It was possible to provide an organic substance-containing gas treatment facility that can effectively adsorb and desorb the organic matter to efficiently recover the organic substance and reliably prevent the risk of explosion.

  The dehumidifying mechanism has a precooler composed of a heat exchanger that receives refrigerant and a subsequent dehumidifying device, and the dehumidifying device can be rotated in a cylindrical container, It is preferable that the zeolite is composed of a honeycomb rotor arranged in a honeycomb shape.

  According to this configuration, the gas to be treated that has been cooled to a low temperature by the precooler is further dehumidified by the honeycomb rotor in which molecular sieves or zeolite is arranged in a honeycomb shape, and is supplied to the downstream side with a stable low dew point. Therefore, the water in the organic matter is more reliably removed and reduced by each device arranged on the downstream side.

  The inert gas is nitrogen, and the nitrogen is heated and sent to the activated carbon adsorption device to desorb organic matter, and the desorbed organic matter is sent to the cooling device. In addition, it is preferable to introduce nitrogen that is not heated.

  According to this configuration, since nitrogen is inexpensive, the processing cost can be reduced, and furthermore, the heat utilization rate of the entire processing equipment can be increased and energy saving can be realized.

  Further, the organic substance-containing gas treatment method according to the present invention is characterized in that moisture contained in a gas to be treated containing organic substances is removed by a dehumidifying mechanism, and the organic substance in the dehumidified gas to be treated is filled with honeycomb activated carbon.・ Introduced into activated carbon adsorbing device and adsorbed and removed, heated inert gas is fed to desorb organic substances adsorbed by this activated carbon adsorbing device from activated carbon, and desorbed by this heated inert gas The separated organic substance is frozen by a cooling device to below zero degree and dehydrated, and the dehydrated organic substance is recovered.

  According to this configuration, it is possible to significantly reduce the moisture content to such an extent that even if the organic substance is collected into a printing ink and the organic substance is reused for printing ink, the moisture content can be greatly reduced. It is possible to provide an organic substance-containing gas processing method capable of effectively adsorbing and desorbing a gas containing and efficiently recovering an organic substance, and reliably preventing the risk of an explosion.

  Moisture removal in the gas to be treated by the dehumidifying mechanism is performed by passing the gas to be treated through a precooler composed of a heat exchanger that receives a refrigerant and a dehumidifying device following the precooler, and the dehumidifying device is a cylindrical container It is preferably composed of a honeycomb rotor in which molecular sieves or zeolite is arranged in a honeycomb shape so as to be rotatable inside.

  According to this configuration, water in the organic substance can be more reliably removed and reduced by each device arranged on the downstream side of the dehumidifying mechanism.

  Nitrogen is used as the inert gas, and the nitrogen is heated and sent to the activated carbon adsorption device to desorb organic matter, and the desorbed organic matter is heated to a path for feeding the cooling device. It is preferable to introduce no nitrogen.

  According to this configuration, the processing cost can be reduced by using inexpensive nitrogen, and the processing cost can be lowered by increasing the heat utilization rate of the entire processing equipment.

  Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic overall configuration of an organic substance-containing gas processing facility according to the present embodiment.

  A schematic structure of this organic substance-containing gas processing facility is shown in FIG. That is, the gas to be treated (organic substance-containing gas) generated from various chemical factories is fed by the feed fan 1 to the precooler 2a and the subsequent dehumidifier 2b constituting the dehumidifying mechanism 2, and dehumidified. The gas to be treated whose moisture has been dehumidified by the mechanism 2 is sent to an activated carbon adsorption device 4 that adsorbs and removes organic substances. Further, the organic substance-containing gas treatment facility includes a device 5 for supplying a heated inert gas to desorb the organic matter adsorbed by the activated carbon adsorption device 4 from the activated carbon, and a desorption by the heated inert gas. The apparatus includes a cooling device 6 that cools the dehydrated organic matter to below zero degree and dehydrates, a recovery device 7 that collects the dehydrated organic matter, and the like.

  The precooler 2 a is configured by a heat exchanger and is supplied with a refrigerant from the blownler 10. In this heat exchanger, the refrigerant is fed and circulated through the pipe 11 by the pump P1 from the brachinler 10 that cools the refrigerant (brine) sent from the brine storage tank T.

  The dehumidifying device 2b following the precooler 2a constitutes, for example, a rotor (honeycomb rotor) in which molecular sieves or zeolite arranged in a honeycomb shape are accommodated so as to be rotatable in a cylindrical container. (For example, about 10 rotations / hour) While the gas to be processed passes through, the moisture in the gas to be processed is removed while the regeneration fan (from the opposite direction to the sealed and separated path) A system in which warm air (about 110 to 150 ° C.) is blown and regenerated from an unillustrated) can be employed. By this dehumidifying device 2b, the gas to be treated can be set to a stable low dew point (for example, −30 ° C. or lower).

  In addition, in order to remove dust etc. in the gas to be treated, before introducing the gas to be treated into the dehumidifying mechanism 2, a prefilter made of various commercially available dust removing filters may be disposed in advance.

  The gas to be treated that has passed through the dehumidifying mechanism 2 is supplied to a plurality of activated carbon adsorption devices 4 through a control valve 3. In FIG. 1, two activated carbon adsorption devices 4 are arranged in parallel. In this way, one can be used for adsorption and the other can be used for desorption / regeneration. Of course, the activated carbon adsorption device 2 may be one or more, and the number, specifications, etc. of the activated carbon adsorption device 2 may be appropriately selected depending on the amount of gas to be treated and characteristics.

  The activated carbon adsorbing device 4 is filled and fitted with honeycomb activated carbon and does not use granular activated carbon or fibrous activated carbon as in the prior art. Therefore, the activated carbon adsorbing device 4 has low ventilation resistance and low pressure loss. It is still characterized by high adsorption capacity. Since the pressure loss of the honeycomb activated carbon is small, the power source of the feeding fan 1 may be small, and the energy consumption is small. The activated carbon adsorbing device 4 may have various configurations. For example, the activated carbon adsorbing device 4 is configured by stacking about 90 to 450 mm of honeycomb activated carbon on a unit having a perforated plate and a fluid jacket.

The specific surface area of the honeycomb active carbon, it is preferred to use those about 200~3000m ² / g, it is more preferable to use those about 300~2500m ² / g, about 400~2000m ² / g It is even more preferable to use a material having a degree.

The through-holes of the honeycomb-like activated carbon are not limited to hexagonal shapes, and various shapes such as squares, rectangles, polygons, circles, and substantially circles can be adopted. The larger the number of through-holes (number of cells), the more contact with the number of objects to be treated and the higher the adsorption capacity, which is preferable. However, if the number of through-holes is too large, the pressure loss increases, making it difficult to manufacture and cost Becomes higher. Therefore, it is preferable hole number about 15 to 2326 pieces / 10 cm ^2, about more preferably from 30 to 1,550 pieces / 10 cm about ^2, about 39 to 1,162 pieces / 10 cm ² approximately and even more preferred.

  The method for producing the honeycomb-shaped activated carbon is not particularly limited. Usually, the activated carbon raw material is added with a binder, formed into a honeycomb shape, carbonized and activated, and then washed with acid as necessary, or the activated carbon itself is used. After being formed into a honeycomb, it is dried and fired.

  The treated exhaust gas from which the organic matter has been adsorbed and removed by the activated carbon adsorbing device 4 is then released into the atmosphere through the control valve 5, but if the organic matter remaining in the treated exhaust gas is not below the emission standard value, further detoxification treatment is performed. Will be released.

  Further, on the downstream side of the activated carbon adsorption device 4, there is provided a device for desorbing and collecting organic substances adsorbed on the honeycomb-like activated carbon. In this case, the relationship between the linear flow rate (LVa) of the gas to be treated to be passed through the honeycomb-like activated carbon and the linear velocity (LVb) of the gas when the organic matter is desorbed from the honeycomb-like activated carbon having adsorbed the organic matter is important. LVb / LVa = 0 to 1 / 10,000 and more preferably LVb / LVa = 1/10 to 1 / 10,000. Within this range, organic substances adsorbed on the honeycomb-like activated carbon can be efficiently desorbed. Specifically, a treatment gas containing an organic substance is passed through honeycomb activated carbon at a linear velocity of 30 to 300 cm / second, and desorption nitrogen is passed at 1/10 to 1 / 10,000 of the linear velocity. It is possible to efficiently desorb organic substances.

  Conventionally, organic substance detachment from the honeycomb-like activated carbon adsorbed with organic substance was performed by supplying pressurized steam of about 1.9 atmospheres heated to about 130 ° C., and was dehydrated with hot air. As a result, when the organic substance is benzene, toluene or xylene (so-called BTX) having a particularly low boiling point, the explosion limit may be reached with the hot air sent for drying. It was difficult to work, and there was a problem that it was necessary to provide explosion-proof equipment and other equipment. Therefore, in order to solve this problem with certainty, in this embodiment, nitrogen, which is an inert gas, is heated to about 90 to 110 ° C., preferably about 100 ° C., and then fed. Of course, other inert gases may be used instead of nitrogen.

  That is, nitrogen is fed from the nitrogen container (gas cylinder or liquid nitrogen container, etc.) 12 through the control valve to the heat transfer oil tank 7 by the nitrogen gas circulation fan 6 to be heat exchanged and adsorbed on the honeycomb activated carbon. It is heated to a temperature somewhat higher than the boiling point of the organic matter, and flows through the pipe 20 and is fed to the activated carbon adsorbing device 4 through the control valve 8. The amount of heat in the heat transfer oil tank 7 is obtained by heating directly or indirectly by attaching a heater 24 or the like. The heat medium in the heat medium oil tank 7 is circulated by the pump P2 and maintained at a predetermined temperature. However, the heat quantity of the heat transfer oil tank 7 may be used by supplying heat generated from other heat sources in the factory. It is not always necessary to use the nitrogen gas circulation fan 6 for feeding nitrogen, and other feeding means may be used. Here, the nitrogen container 12, the nitrogen gas circulation pump 6, the heat medium oil tank 7, and the like constitute a heated gas feeding device.

  The organic matter adsorbed on the honeycomb-like activated carbon of the activated carbon adsorption device 4 is desorbed by heated nitrogen, and is fed to the first cooler 13 through the desorption nitrogen control valve 9 together with nitrogen, and is somewhat cooled. Refrigerant is fed and circulated from the first chiller unit 16 to the first cooler 13 by a heat exchanger cooling water circulation pump P3. Reference numeral 17 is a cooling water tank equipped with a supply pump P4 for storing cooling water to be sent to the first chiller unit 16.

  In addition, it is preferable to introduce the organic substance desorbed from the honeycomb-shaped activated carbon with heated nitrogen to the first cooler 13 through the pipe 21 without heating a part of nitrogen from the nitrogen container 12. If it does in this way, the heat consumption in the 1st cooler 13 may be small, the heat utilization factor of the whole installation increases, and it becomes energy saving. Reference numeral 22 is a cooling valve for controlling the amount of cooling nitrogen introduced.

  Furthermore, nitrogen containing organic matter is fed into a plurality of narrow tubes arranged inside the second cooler 14 and cooled, and the organic matter is made liquid. In that case, since the second cooler 14 cools nitrogen containing organic matter to zero degrees or less, preferably -10 ° C. or less, the moisture in the nitrogen is frozen on the surface of the thin tube and separated and removed. In FIG. 1, two second coolers 14 are arranged in parallel to increase the efficiency of moisture removal, but may be one or more.

  Moreover, nitrogen from which organic substances and moisture have been removed can be reused by being fed to a heat transfer oil tank 7 for heating the nitrogen. Reference numeral 23 is a control valve for controlling the supply amount of nitrogen.

  The liquid organic substance is further sent to a collection tank 15 such as a decanter and collected as a high-purity organic substance. By doing in this way, the dissolved water | moisture content in high purity organic substance can be made into about 0.5 weight% or less. Therefore, when the organic substance is ethyl acetate, even if it is used as a solvent for gravure printing ink, it is possible to reliably suppress the occurrence of ink bleeding. The first and second coolers 13 and 14 constitute a cooling device, and the decanter 15 constitutes a recovery device. However, depending on the organic matter in the gas to be treated, the decanter 15 is not necessarily required, and other recovery means may be used.

  The refrigerant is supplied from the second chiller unit 18 to the second cooler 14 via the heat exchanger 19, and is circulated by the brine circulation pump P5.

An example in which an exhaust gas containing ethyl acetate is treated as an organic substance-containing gas that is a gas to be treated will be described. The relative humidity in the atmosphere is about 60%, and the exhaust gas flow rate (about 300 Nm ³ / h) containing ethyl acetate (about 2000 ppm by weight) is cooled to 5 ° C. or less with a precooler as shown in FIG. Then, after the dew point was set to −30 ° C. or less with a honeycomb rotor which is a dehumidifying device, the dehydrate was supplied to the activated carbon adsorbing device 4 containing the honeycomb-like activated carbon to be adsorbed. The activated carbon adsorption device 4 includes about 20,000 honeycomb activated carbons and has a size of 3,000 × 4,500 × height of 1,000 mm. A first cooler 13 in which nitrogen heated to about 100 ° C. is passed through the honeycomb-shaped activated carbon having adsorbed ethyl acetate to desorb ethyl acetate, and nitrogen containing organic matter is cooled to about 15 ° C. or less; Subsequently, the 2nd cooler 14 cooled to about -10 degreeC was passed. The liquid ethyl acetate finally recovered from the decanter was about 137 kg / h (recovery rate: about 97%), and the dissolved water contained in this ethyl acetate was 0.35% by weight.
[Another embodiment]
(1) In the above embodiment, an example of processing a gas to be processed having ethyl acetate as an organic substance has been shown. However, the present invention is not limited to this, and the present invention is widely used when it is desired to reduce moisture in the recovered organic substance. Can be applied.

  The present invention can be widely applied when processing gases containing organic substances discharged from various chemical industries, food industries, paper industries, pharmaceutical industries, and the like.

Schematic overall flow diagram of an organic substance-containing gas processing facility according to an embodiment of the present invention

Explanation of symbols

2 Dehumidifying mechanism 2a Precooler 2b Dehumidifying device 4 Activated carbon adsorption device 6, 7, 12 Heated gas feeding device 13, 14 Cooling device 15 Recovery device

Claims (6)

A dehumidifying mechanism for removing moisture contained in the gas to be treated containing organic matter, an activated carbon adsorbing device filled with and fitted with honeycomb-like activated carbon for adsorbing and removing the organic matter in the dehumidified gas to be treated, and the activated carbon A heated gas supply device that feeds a heated inert gas to desorb the organic matter adsorbed by the adsorption device from the activated carbon, and the organic matter desorbed by the heated inert gas is frozen to below zero degree. An organic matter-containing gas processing facility comprising a cooling device for dehydration and a recovery device for collecting the dehydrated organic matter. The dehumidifying mechanism has a precooler composed of a heat exchanger that receives refrigerant and a subsequent dehumidifying device, and the dehumidifying device can be rotated in a cylindrical container, 2. The organic substance-containing gas treatment facility according to claim 1, wherein the zeolite comprises a honeycomb rotor arranged in a honeycomb shape. The inert gas is nitrogen, and the nitrogen is heated and sent to the activated carbon adsorption device to desorb organic matter, and the desorbed organic matter is sent to the cooling device. 3. The organic substance-containing gas treatment facility according to claim 1 or 2, wherein unheated nitrogen is introduced into the atmosphere. Moisture contained in the gas to be treated containing organic substances is removed by a dehumidifying mechanism, and the organic substance in the dehumidified gas to be treated is filled and mounted with honeycomb-like activated carbon, introduced into the activated carbon adsorption device, and adsorbed and removed. In order to desorb the organic matter adsorbed by the activated carbon adsorption device, heated inert gas is fed, and the organic matter desorbed by the heated inert gas is frozen to below zero degree by the cooling device and dehydrated. An organic substance-containing gas treatment method for recovering dehydrated organic substances. Moisture removal in the gas to be treated by the dehumidifying mechanism is performed by passing the gas to be treated through a precooler composed of a heat exchanger that receives a refrigerant and a dehumidifying device following the precooler, and the dehumidifying device is a cylindrical container The organic substance-containing gas treatment method according to claim 4, wherein the organic substance-containing gas treatment method comprises a honeycomb rotor in which molecular sieves or zeolite is arranged in a honeycomb shape so as to be rotatable inside. Nitrogen is used as the inert gas, and the nitrogen is heated and sent to the activated carbon adsorption device to desorb organic matter, and the desorbed organic matter is heated to a path for feeding the cooling device. The organic substance containing gas processing method of Claim 4 or 5 which introduce | transduces nitrogen which is not.

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