JP5387991B2 - Operation method of volatile organic compound adsorption tower - Google Patents

Description

  The present invention relates to an operation method for reducing a load applied to an apparatus when processing a volatile organic compound from a gas before discharging the gas containing the volatile organic compound.

  Exhaust gas generated from factories may contain volatile organic compounds that cause problems if discharged into the atmosphere as they are. In this case, before exhaust gas is discharged into the atmosphere, the contained volatile organic compounds must be treated. As a method for this, an adsorption tower containing activated carbon or other adsorbent is used to adsorb volatile organic compounds contained in exhaust gas to the adsorbent, reduce the concentration in the gas and discharge it to the atmosphere. An adsorption / desorption system is generally used in which a volatile organic compound is desorbed to make the adsorption tower reusable and the volatile organic compound is treated.

  For the above desorption, it is necessary to bring a gas not containing a volatile organic compound into contact with the adsorbent. Since adsorption cannot be performed simultaneously with desorption by a single adsorption tower, desorption is preferably carried out promptly. As a method of speeding up desorption, a method of introducing a large amount of desorption gas, a method of reducing pressure by sucking with a vacuum pump, a method of introducing high-temperature desorption water vapor to promote desorption which is an endothermic reaction, etc. There is.

  In order to introduce high-temperature desorption water vapor, a large amount of fuel is consumed for its heating, so a method for saving fuel has been studied. In Patent Document 1, desorbed water vapor containing the recovered volatile organic compound is guided to a combustion furnace, and the volatile organic compound is burned as a fuel (Claim 1). It is described that the steam is heated (Claim 2).

  On the other hand, in Patent Document 2, an adsorption tower that sucks with a vacuum pump is provided with a plurality of adsorbent layers provided with an adsorbent, thereby increasing the desorption speed without using a high-performance vacuum pump. A method has been proposed. The adsorption tower described in this document introduces a gas containing alcohols, which are volatile organic compounds, from below, and extracts exhaust gas from which alcohols have been reduced from above (Patent Document 2 FIG. 1). Desorption gas introduction holes (purge air introduction pipes) are provided between the uppermost adsorbent layer and each adsorbent layer, and desorbed gas exhaust holes (exhaust conduits) are adsorbed between each adsorbent layer and the lowermost layer. It is provided at a location below the agent layer (Patent Document 2 [0039]). Then, an automatic valve of a desorption gas introduction hole and an exhaust conduit underneath with one adsorbent layer is opened sequentially from the top as a set and closed as soon as desorption is completed (Patent Document 2 [0042] ] To [0045]).

  However, this method is a method in which each layer is desorbed stepwise by suction, and in the method using heated desorption water vapor, even if the method of Patent Document 2 in which gas is sucked from each layer is adopted, such an effect is not obtained. Absent.

  Further, in Patent Document 3, when performing adsorption of a volatile organic compound and desorption of the volatile organic compound by vapor using a plurality of adsorption devices, the total demand for vapor does not exceed a certain level. Describes a method of advancing the start timing of the desorption process of one desorption apparatus.

JP 2007-2222736 A JP 2002-293754 A JP 2010-005579 A

  However, when a large amount of water vapor from which a volatile organic compound is desorbed as in Patent Document 1 is supplied to the combustion furnace at a time, the calorific value of the combustion furnace increases and the heat load on the apparatus also increases. If the size is not large, long-term use will be difficult. On the other hand, the amount of water vapor desorbed shows a peak immediately after its start and then decreases rapidly. Therefore, if the combustion furnace is enlarged, the fuel is insufficient after the peak and the calorific value is small. It becomes too much. For this reason, the amount of the volatile organic compound desorbed by water vapor supplied to the combustion furnace is required to be leveled throughout the desorption process.

  Also, if the amount of water vapor is reduced at the start of desorption, and the amount of water vapor is increased as desorption proceeds, it is possible to prevent the combustion furnace from becoming too hot. Attempting to adjust the volume should not be done because it increases the load on the combustion furnace.

  As described in Patent Document 2, when a plurality of supply ports are provided in the height direction of the adsorption tower and the supply ports are opened alternately in order from the supply port closer to the supply port, Since the region of the adsorbing layer to be desorbed is limited, the peak height of the calorific value can be suppressed. However, each time the individual supply ports are opened, the peak of the calorific value is generated many times. For this reason, even if the maximum amount of heat could be suppressed, as a result, it was not sufficient for reducing the thermal load applied to the apparatus.

  Patent Document 3 describes a method for adjusting the timing of desorption, which is necessary for the entire apparatus when performing desorption in parallel to a plurality of adsorption towers operated in parallel. In order to keep the peak amount of water vapor below a certain level, the desorption start timing of the individual adsorption towers is shifted, which can be applied only to an environment where each adsorption tower is independent. Moreover, since the peak size for each adsorption tower does not change, the reduction of the heat load on the combustion furnace is insufficient.

  Therefore, an object of the present invention is to reduce the heat load applied to the combustion furnace at a higher level than the method according to Patent Document 2.

In the present invention, a desorption water vapor supply port branched from one or a group of combustion furnaces is separated from one end of a supply outlet side for supplying water vapor after desorption of the adsorption layer to the combustion furnace. A plurality of locations are provided, and at least one supply port is provided at a location for supplying desorption water vapor directly to the adsorption layer,
In opening each supply port,
The supply port to be opened next is opened at least before closing the supply port opened immediately before,
In closing each supply port, at least the supply port opened immediately before is opened after a lapse of a predetermined time, thereby solving the above-mentioned problem. Here, the term “immediately before” does not mean the moment before, but means that the procedure was performed immediately before in the order of the procedure.

  Here, the combustion furnace which supplies desorption water vapor | steam is fixed in one or a group. And the place away from the end on the outlet side, which is the outlet at the time of desorption of the adsorption layer of the adsorption tower, is the place where the part directly supplied to the adsorption layer and the end on the opposite side to the outlet side Including both where the layer is not filled. When at least one supply port supplies desorption water vapor directly to the adsorption layer, the supply port is basically not the entire area of the adsorption layer, but basically only the water vapor adsorbed on the outlet side from the supply port. Means to be desorbed. The supply port provided at a position farther from the supply port than the end opposite to the supply port of the adsorption layer is desorbed with the desorption water vapor introduced from the supply port over the entire adsorption layer. To do.

  In addition, when the supply ports are opened and closed under the above conditions, the desorption water vapor that newly flows into the second and subsequent supply ports is the maximum desorption water vapor. Therefore, the peak of the amount of water vapor to be desorbed is greatly reduced as compared with the case where the entire amount flows into the newly opened supply port as in Patent Document 2.

  After that, if it is kept open for a long period of time, it will continue to occupy a part of the desorption water vapor even though the water vapor to be desorbed has disappeared around the supply port. The supply port is closed after a certain period of time elapses. After the peak has passed, the amount of volatile organic compounds that are desorbed and supplied to the combustion furnace gradually decreases, so by closing the supply port after a certain amount of time has passed, Along with the closing of the supply port, even if a large amount of water vapor flows into the supply port opened after that, the amount of desorption increases slightly, and a sudden increase peak does not appear.

  Specifically, the second supply port is opened at the end on the outlet side of the adsorption layer of the adsorption tower, or in the pipe from there to the combustion furnace, by the opening of the first supply port. It is preferable that the increase be made after the amount of the organic matter starts to increase and before the increase reaches the maximum value, and it is particularly preferable to judge by the amount of the organic matter in the vicinity of the outlet of the adsorption tower. When the second supply port is opened, the desorption water vapor supplied to the first supply port is halved, so that the amount of desorption can be reduced and the peak can be lowered. However, if this timing is measured by the combustion furnace, since the organic substance has already reached the combustion furnace at the time of detection, the peak leveling effect due to the opening of the second supply port is not in time. For this reason, it is better to measure before the combustion furnace, that is, on the adsorption tower side. Rather than observing the change in the piping, it is better to observe the change near the outlet until the first wave of organic matter reaches the combustion furnace. This is preferable because it can earn as long as possible.

  In addition, after the start of desorption, the supplied desorption water vapor F is cooled in the adsorption layer at the initial stage of desorption and is mostly condensed and discharged as a large amount of water (drain). When the temperature of the adsorption layer rises, it partially condenses and becomes a mixture of water (mist) and steam. Therefore, as the desorption process proceeds, the rate of steam increases and the temperature rises. For this reason, before carrying out the present invention, the amount of organic matter contained by collecting a gas sample from the air in the vicinity of the outlet at the end of the adsorption tower by opening the first supply port in advance. When the temperature is measured at that location, the degree of progress of the desorption process can be grasped almost in real time by measuring the temperature when the invention is carried out. However, since the relationship between the progress of this desorption process and temperature is almost similar in most adsorption towers heated from room temperature to the boiling point of water, the amount of organic matter in the air is measured in real time. The progress of the desorption process can be grasped more easily.

  The timing of closing each supply port must be at least after the next supply port is opened, and after the first supply port is opened, one supply port is always opened. In particular, when a plurality of supply ports are provided in series in the height direction of the tower, the two supply ports are always opened after the second supply port is opened, that is, the third and later. When the supply port of the product is opened simultaneously with the closing of the supply port opened two times before that, the amount of steam supplied to each supply port is not reduced excessively, and it is operated appropriately without being concentrated too much. This is preferable.

  The third and subsequent supply ports are opened two minutes or more after the previous supply port is opened, and the steam supplied from the previous supply port reaches the combustion furnace. This should be done before. If it is less than 2 minutes, the amount of steam supplied from each supply port is too small and desorption does not proceed sufficiently. On the other hand, even if it takes longer than the time for the supplied steam to reach the combustion furnace, the desorption time becomes too long, and the working efficiency deteriorates.

  The order in which the supply ports are opened is sequentially opened from the supply port closer to the supply port. Therefore, the supply port to be opened last is basically the supply port located farthest from the supply port. However, this is not necessarily the case when the inside of the adsorption layer is partitioned in parallel. When the inside of the adsorption layer is partitioned in parallel and there is a supply port for supplying desorption water vapor only to each partitioned region, after opening one supply port, the supply port to be opened next is another Even if there is an unopened supply port close to the supply port depending on the area, it is a supply port that supplies to the same partitioned area as the previously opened supply port and is farther from the supply port than the previously opened supply port Even if the supply port located at 1 is opened first, the problem that the peak rises does not occur. This is because the respective areas do not interfere with each other. In particular, when the capacity, volume and horizontal cross-sectional area of the adsorption tower are large and it is difficult to desorb at once, by providing such a parallel partition, desorption can be performed independently for each partitioned area. By performing the above, it is possible to suppress desorption leakage. In the case of such a large-scale adsorption tower, if a plurality of supply ports having a plurality of stages are provided in series in each of the regions partitioned in parallel, it is easy to ensure desorption.

  In addition, even if there are parallel partitions in the adsorption layer, if there is no partition at a location farther from the outlet than the adsorption layer, and a supply port that opens at the end is provided there, it opens at the end. The supply port can introduce and remove desorption water vapor into all the regions that are in parallel to ensure complete desorption. In addition, when there are parallel partitions, after all the supply ports are opened, once all the supply ports that have been closed are opened, it is possible to thoroughly remove and attach all the partitioned regions.

  On the other hand, when there are no partition and there are multiple supply ports that are multistage in series, the desorption water vapor introduced from the supply port farther from the supply port has a portion of the adsorption layer closer to the supply port than that. Since all can be desorbed, the significance of performing such simultaneous opening is low, and if an outlet that opens last is provided at a location farther from the outlet than the adsorbing layer, desorption can be performed thoroughly.

  According to the present invention, when the adsorption tower for adsorbing and treating the volatile organic compound is operated, the amount of the volatile organic compound supplied to the combustion furnace is leveled, so that stable operation can be performed in a small combustion furnace. it can. Since the heat load applied to the combustion furnace itself is reduced, the life of the combustion furnace can be improved.

Configuration diagram of adsorption tower, combustion furnace, etc. for implementing the first embodiment Flow chart in the first embodiment Conceptual diagram of changes in temperature and amount of volatile organic compounds when one supply port is opened, and the opening timing of the second supply port based on that change Configuration diagram of adsorption tower for implementing the second embodiment Configuration diagram of adsorption tower for implementing the third embodiment Example graph

  Embodiments of the present invention will be described below. This invention makes it possible to discharge the volatile organic compound-containing gas A into the atmosphere as a treated gas B having a reduced concentration, and recovers the volatile organic compound and uses it as a fuel. This is related to the operation method of the apparatus.

  The volatile organic compound to be treated in the present invention is an organic compound that can be converted into a gas when heated at normal pressure, and particularly, a liquid that is liquid at room temperature is easily adsorbed. Examples thereof include hydrocarbon solvents such as alcohols having about 1 to 8 carbon atoms such as methanol, ethanol and isopropyl alcohol, and aromatic organic compounds such as toluene and benzene.

  FIG. 1 shows a first embodiment of an overall view of a volatile organic compound processing apparatus embodying the present invention. This volatile organic compound processing apparatus includes an adsorption tower 11, a combustion furnace 13, and a heat exchanger 14.

  The adsorption tower 11 (11a, 11b) has a substantially cylindrical shape, and is provided with a single porous plate 20 in the vicinity of the lower end. The porous plate 20 has a size that covers the entire cross section of the adsorption tower 11, and an adsorption layer 12 filled with an adsorbent that adsorbs volatile organic compounds and can be desorbed by heating is provided on the porous plate 20. . Examples of the adsorbent include activated carbon. The adsorption layer 12 does not reach the upper and lower ends of the adsorption tower 11 and has hollow portions on both the upper and lower sides.

  The inlet 17 for the volatile organic compound-containing gas A is provided on the upper end side of the adsorption layer 12 of the adsorption tower 11, and the exhaust port 18 for the post-treatment gas B is provided on the lower end side of the adsorption layer 12. . The discharge port 18 discharges into the atmosphere. Moreover, although not shown in figure at the bottom part on the lower end side, there is provided a drainage port for discharging water produced mainly by condensation of steam. The volatile organic compound-containing gas A is generated by another apparatus or the like, and is a processing target for removing the volatile organic compound to form a post-processing gas B. For example, various exhaust gas etc. are mentioned. When the volatile organic compound-containing gas A passes through the adsorption layer 12 between the introduction port 17 and the discharge port 18, the volatile organic compound is adsorbed by the adsorbent, and the volatile organic compound It becomes the after-treatment gas B having a reduced concentration.

  In addition, in the adsorption layer 12 of the adsorption tower 11, supply ports 15 </ b> A to 15 </ b> C for desorption water vapor F consisting of a plurality of stages are provided at substantially equal intervals in order from the top. These supply ports pass through the outer wall of the adsorption tower 11, reach the inside of the adsorption layer 12, and are opened so as to easily diffuse into the adsorption layer 12.

  Further, a desorption water vapor F supply port 15 </ b> D is also provided on the lower end side of the adsorption layer 12. These supply ports 15 </ b> A to 15 </ b> D are provided at the ends of pipes branched from desorption water vapor F generated from one combustion furnace 13 described later. That is, the amount of the desorption water vapor F to be supplied is that the supply ports that are open among the supply ports 15A to 15D are almost equally shared. The supplied desorption water vapor F is cooled by the adsorption layer 12 at the initial stage of desorption, and most of the water is condensed and discharged from the drain as a large amount of water (drain). When the temperature rises, it partially condenses to become a mixture of water (mist) and steam, desorbs the volatile organic compound adsorbed on the adsorption layer 12, and forms a volatile organic in a gas or droplet (mist) state. It rises while entraining the compound and exits from the outlet 16 provided at the upper end of the adsorption tower 11. Accordingly, each of the supply ports 15A to 15D has a common route to the outlet 16. Hereinafter, the organic compound-containing water vapor K exiting from the outlet 16 refers not only to a pure vapor state but also to a mixture of water and vapor and droplets (mist) of desorbed organic compound.

  Valves are respectively attached to the pipes leading to the supply ports 15A to 15D, and the opening and closing can be independently controlled independently. At the time of operation, the supply port 15A that is closest to the supply port 16, that is, the uppermost supply port 15A in this embodiment is opened in order.

  A contained water vapor temperature sensor 25 is provided in the vicinity of the outlet 16, and the temperature of the organic compound-containing water vapor K traveling to the combustion furnace 13 can be measured. As described above, the organic compound-containing water vapor K is a mixture of water (mist) and steam, but since the ratio of the steam increases as the temperature of the adsorption layer 12 rises, the detection temperature of the contained water vapor temperature sensor 25 increases. That is, the approximate progress of the desorption process can be grasped from this detected temperature. Since the supply and temperature of the desorption water vapor are basically the same, the progress of the desorption process can be grasped over time, but it is affected by external conditions such as temperature and humidity, so it is grasped by temperature. Is desirable.

  The organic compound-containing water vapor K exiting from the outlet 16 is sent to the combustion furnace 13 through the water vapor pipe 21. The combustion furnace 13 is for generating heat for generating the desorption water vapor F, and has a fuel supply port 22 for supplying the fuel D therefor. The water vapor supply port 23 for supplying the organic compound-containing water vapor K sent from the 11 supply / outlets 16 is also provided. Of course, the combustion furnace 13 also has a burner and a chimney (both not shown). Furthermore, it has a combustion furnace temperature sensor 24 for measuring the internal temperature. The heat generated in the combustion furnace 13 is supplied to the heat exchanger 14.

  The heat exchanger 14 includes a circulation port 31 that supplies water E that is a source of water vapor, and heats the water E to generate desorption water vapor F. The generated desorption water vapor F is supplied to the supply ports 15A to 15D of the adsorption tower 11 through the desorption water vapor supply path 32, and a branch 33 is provided in the middle, and one of the branches is heat exchange. A circulation path 34 that circulates to the vessel 14 is formed. This circulation path has a function of spraying water E, and is connected to the heat exchanger 14 through the circulation port 31. Until the desorption water vapor F to be generated reaches a sufficiently high temperature, the generated water vapor goes around this circulation path and is not discharged to the adsorption tower 11 or the outside, thereby improving the thermal efficiency. Further, the heat exchanger 14 has a water vapor temperature sensor 36 for measuring the internal temperature in order to adjust the temperature of the generated water vapor.

  Another branch 35 is provided between the other side of the branch 33 and the supply ports 15 </ b> A to 15 </ b> D of the adsorption tower 11. One of the branches 35 is connected to an open port 39 to the atmosphere, and can be released into the atmosphere when the internal pressure in the desorption water vapor supply path 32 becomes excessive or the desorption water vapor F remains. A valve that can be opened and closed as necessary is provided.

  On the other side of the branch 35 of the desorption water vapor supply path 32, another branch 40 is provided, and each supply of the adsorption towers 11 (11a, 11b) is provided in parallel. It is connected to the mouths 15A to 15D. That is, while the adsorption column 11a is adsorbing the volatile organic compound-containing gas A, the other adsorption column 11b is desorbed by supplying the desorption water vapor F from the supply ports 15A to 15D. , The treatment of the volatile organic compound-containing gas A can always be continued. However, desorption in one of the adsorption towers must be completed in a time until the adsorption capacity of the other adsorption tower is attenuated and reaches the limit as will be described later.

  The execution procedure of the operation method of the volatile organic compound processing apparatus having the above configuration will be described. In the volatile organic compound processing apparatus according to the present invention, first, the volatile organic compound contained in the volatile organic compound-containing gas A is introduced into one adsorption tower 11 (11a or 11b), and the adsorbent of the adsorption layer 12 is obtained. Adsorb to. The treated gas B that has passed through the adsorption layer 12 exits from the outlet 18 and is released into the atmosphere. This adsorption work is performed until a certain period of time elapses or until the adsorption capacity becomes below a certain level. In order to stop the adsorption by detecting a decrease in the adsorption capacity, a volatile organic compound detection device (not shown) is provided at the discharge port 18 where the concentration of the volatile organic compound contained in the gas B after the treatment is determined. A control circuit is provided that, when measured and exceeds a predetermined value, interprets that the adsorption capacity of the adsorption layer 12 has reached its limit and issues a command to close the valve of the inlet 17.

  On the other hand, preparation for desorption is proceeded before the adsorption is completed. Since the desorption water vapor F cannot be supplied immediately, if heating is started after the completion of adsorption, a time lag occurs before the desorption begins, and the originally necessary adsorption process is stopped.

  The preparation stage of this desorption process will be described using the flow of FIG. First, combustion of the fuel D is started in the combustion furnace 13, and the air in the circulation path 34 (32 → 33 → 34 → 31) of the desorption water vapor F is circulated by a fan (not shown) provided in the path. (S11). When the water temperature is detected by the water vapor temperature sensor 36 and a water control circuit (not shown) confirms that the air temperature is equal to or higher than the set temperature T1 at which water vapor can be generated (S12), the branch 33 to the heat exchanger 14 The valve of the water supply port 38 of the water E into the return circulation path 34 is opened, and water E is sprayed to generate water vapor in the heat exchanger 14 (S13). In the heat exchanger 14, the temperature of the water vapor generated by the water vapor temperature sensor 36 is detected, and the open port 39 is used until the desorption water vapor F reaches a temperature T2 suitable for desorption (S14) or until the adsorption is completed. The valve is opened and released into the atmosphere (S15). This is because desorption is an endothermic reaction, and desorption does not proceed quickly unless the steam is sufficiently hot. Here, the desorption water vapor F is superheated water vapor or saturated water vapor.

  When the adsorption in the adsorption tower 11 is completed and the desorption water vapor F becomes equal to or higher than the predetermined temperature T2 (S14), the open port control circuit (not shown) closes the valve to the open port 39, and the most outlet The valve of the desorption water vapor F to the supply port 15A close to 16 is opened (S16). The desorption water vapor F supplied to the supply port 15A desorbs the volatile organic compound adsorbed on the upper layer portion of the adsorption layer 12, and becomes an organic compound-containing water vapor K, which is delivered from the outlet 16 (S17).

When the organic compound-containing water vapor K reaches the water vapor temperature sensor 25 provided in the vicinity of the outlet 16, this sensor detects a temperature rise (S 18). Although this temperature rise depends on the equipment of the adsorption tower 11, it rises according to the progress of the desorption process as described above. Specifically, when the temperature value starts to rise from room temperature and rises to about 40 ° C., the operation is performed assuming that the organic compound-containing water vapor K has reached. The time from when the supply port 15A is opened until the arrival of the organic compound-containing water vapor K is detected until the adsorption layer 12 is warmed and the desorption water vapor F passes through the adsorption layer 12 as a mixture of mist and vapor. If, there is a time lag T _rag the combined time to reach the containing steam temperature sensor 25 provided near the test outlet 16 from exits the adsorption layer 12.

Organic compounds containing water vapor K detected after opening the supply port 15A after the above time lag T _rag has elapsed, since the most desorption immediately after the start of the desorption proceeds, rapidly the amount of volatile organic compounds containing It shows a behavior that it rises and shows a maximum value and then gradually decreases. Further, the temperature indicated by the contained water vapor temperature sensor 25 increases according to the progress of the desorption process. An example of the change in the amount and temperature of the volatile organic compound is shown in FIG. Here, the temperature change in the vicinity of the outlet 16 shown in FIG. 3, that is, the temperature change due to the organic compound-containing water vapor K is a change when only the supply port 15A is opened alone, and the supply port 15B is changed based on this change. The opening timing will be determined.

  Note that the volatile organic compound that is desorbed when the supply port 15A is opened is not the entire region of the adsorption layer 12, but only the portion above the supply port 15A, compared to the case where the entire region is desorbed collectively. The maximum value of the amount of volatile organic compounds is sufficiently small. In this embodiment, the portion above the supply port 15A is about a quarter of the entire adsorption layer 12, and the maximum value of the volatile organic compound to be desorbed is also the case where the entire region is desorbed collectively. Compared to about a quarter. Then, the next supply port 15B is opened until the amount of the volatile organic compound reaches the maximum value and the temperature reaches the minimum value, thereby further reducing the maximum value and the minimum value and leveling the whole. To do.

  However, if the supply port 15B is opened immediately after the supply port 15A is opened, the peak indicating the maximum value of the amount of the volatile organic compound is too close and overlapped, and the leveling effect may be insufficient. For this reason, the opening of the supply port 15B should be performed after the desorption water vapor F supplied from the supply port 15A has progressed to some extent.

Specifically, when the supply port 15B is opened (S19), when the water supply to the adsorption tower 11 is reached by opening the supply port 15A, the atmosphere near the outlet 16 starts to warm and reaches 40 ° C. It is preferable that the time T _{open0 be} from the time point to the time point when the adsorption layer 12 is sufficiently warmed and the atmosphere near the outlet 16 reaches 90 ° C. When the vicinity of the outlet 16 exceeds 90 ° C., the most advanced organic compound-containing water vapor K reaches the combustion furnace 13 in most cases, and the temperature rise peak of the combustion furnace 13 due to the opening of the supply port 15B. This is because the response of the leveling effect is lowered. Although it depends on the length of the contained steam pipe 21 from the outlet 16 to the combustion furnace 13, it is more preferable to open it before the time when it reaches 80 ° C. because it reaches the combustion furnace 13 easily. FIG. 3 shows a case where the temperature of the combustion furnace 13 is rapidly increased almost simultaneously with the temperature of the outlet 16 reaching 90 ° C., and the organic compound-containing water vapor K reaches at this point. By increasing the transfer distance of the contained steam pipe 21 to the combustion furnace 13, the arrival to the combustion furnace 13 can be delayed, and conversely, the arrival to the combustion furnace 13 can be accelerated by shortening the distance. There are some errors depending on the design, while fine adjustments can also be made by device design.

Therefore, from opening the supply port 15A, time _{T open1} of up to open the supply port 15B _is a _{T rag <T open1 <T rag} + T open0. This relationship is shown in the lower part of FIG. The origin is when the supply port 15A is opened. In the figure, the hatched band indicates the time during which each supply port is open.

  When the supply port 15B is opened (S19), the previous supply port 15A remains open. When the supply port 15B is opened, the desorption water vapor F having the same supply source is dispersed in the supply port 15A and the supply port 15B, so that the desorption water vapor F supplied to the supply port 15A is virtually halved. . Thereby, since the pressure which extrudes the organic compound containing water vapor | steam K in the containing water vapor | steam piping 21 also falls temporarily, the maximum value of the volatile organic compound desorbed by the desorption water vapor F supplied from the supply port 15A is supplied. This is further reduced as compared with the case where the opening 15B cannot be opened, and the temperature rise peak of the combustion furnace 13 is also leveled.

By opening the supply port 15B, desorption occurs particularly in the region of the supply port 15A and the supply port 15B in the adsorption layer 12. Thereby, the organic compound-containing water vapor by the desorption water vapor F supplied to the supply port 15B is supplied to the water vapor temperature sensor 25 after the time T _lag2, which is longer than the T _rag when the supply port 15A is opened, elapses. To reach. This is because the time required to pass through the adsorption layer 12 is longer at the supply port 15B than at the supply port 15A. However, the maximum value of the content of the organic compound indicated by the organic compound-containing water vapor reached by opening the supply port 15B and the peak of the temperature rise of the combustion furnace 13 caused thereby are larger than the maximum value generated by opening the supply port 15A. Will be small enough. The amount of the desorption water vapor F flowing into the supply port 15B is half of the total amount of the desorption water vapor F supplied to the supply port 15A, and the desorption water vapor F supplied to the supply port 15A is also halved at the same time. Since the amount of the organic compound-containing water vapor derived from the supply port 15A is also almost halved, the maximum values derived from the supply port 15B are all leveled.

On the other hand, after a certain period of time has elapsed since the supply port 15B was opened, the next supply port 15C was opened before _Trag2 passed and the water vapor supplied from the supply port 15B reached the combustion furnace 13. (S20). In accordance with this, the supply port 15A is closed. If the supply port 15A is left open, the desorption water vapor F flowing into each of the supply ports 15A to 15C is divided into three equal parts, and the desorption efficiency from the supply port 15C becomes too low. Almost all volatile organic compounds have already been desorbed in the adsorbing layer 12 above the supply port 15A, and the corresponding amount of water vapor is routed to the supply port 15C. At this time, the supply port 15B remains open.

  The time from when the supply port 15B is opened to when the supply port 15C is opened is after the temperature rise of the combustion furnace 13 due to the arrival of the organic compound-containing water vapor K derived from the supply port 15A is indicated. It is preferable to set until the temperature rise of the combustion furnace 13 due to the arrival of the organic compound-containing water vapor K derived from 15B is shown. Specifically, although it depends on the scale of the adsorption tower, in most cases, 2 to 15 minutes after the supply port 15B is opened is a suitable time.

  However, the closing of the supply port 15A and the opening of the supply port 15C do not need to be performed at the same time. If the supply port 15A is closed after providing a slight time lag, the desorption water vapor F flowing into the supply port 15C. Is a third of the total at the first peak, and shows a multi-stage rise in which the desorbed water vapor F increases to a half after the peak, and the volatile organic compound contained in the organic compound-containing water vapor The amount can be further leveled.

  Similarly, the next supply port is also two minutes or more after the previous supply port is opened, and the organic compound-containing water vapor K derived from the previous supply port reaches the combustion furnace. By closing the supply port opened two times ago, the maximum value of the amount of volatile organic compounds is suppressed while the amount of water vapor F to be removed is secured, and leveling is achieved. (S21). Although the four supply ports 15A to 15D are shown in the figure, even when the supply ports are provided in multiple stages, the maximum value of the amount of the volatile organic compound can be suppressed and leveled by the same method. it can.

  The last supply port 15 </ b> D in this embodiment is provided not at the adsorption layer 12 but at the bottom of the adsorption tower 11 below the adsorption layer 12. It can be desorbed throughout. If it is below the adsorbing layer 12, the entire adsorbing layer 12 is spread, but it is most preferable that the adsorbing layer 12 is provided at the bottom in order to diffuse evenly.

  The timing for closing the last two supply ports may be closed at the same timing as described above, except that there is no supply port that opens at the same time (S22, S23). Further, only the last one supply port 15D is opened after taking a longer time, and after a certain period of time that can be experimentally determined that sufficient desorption has proceeded since the last supply port 15D was opened. There may be. However, it is necessary to finish before the limit of adsorption in the other adsorption tower 11b comes. The desorption of the adsorption tower 11a is completed by closing the last supply port 15D.

  After the closure, the excess desorption water vapor F is discharged from the open port 39 to the outside (S24), the temperature of the combustion furnace 13 is not lowered, and the generation of the desorption water vapor F in the heat exchanger 14 is not stopped. Is preferred. This is because once the operation is stopped, the heat load applied to the apparatus when heating again is large, and it takes too much time for preparation, and the time loss generated until the start of desorption of the next adsorption tower 11b also increases. If the desorption water vapor F continues to be generated, the steps from S11 to S15 can be omitted and the process can be started promptly from S16 in the next desorption performed in the adsorption tower 11b.

  Thereafter, the adsorption tower 11a that has been desorbed ends the adsorption due to the lowering of the adsorption capacity of the other adsorption tower 11b, and again takes the adsorption from the volatile organic compound-containing gas A.

  By opening and closing the supply ports 15A to 15D as described above, the load applied to the combustion furnace 13 is reduced by leveling the amount of the volatile organic compound, not the combustion furnace 13 having an excessive capacity. However, the desorption process can be performed in the combustion furnace 13 having a minimum size. However, even if leveling is performed in this way, the total amount of fuel and volatile organic compounds introduced into the combustion furnace 13 temporarily increases when the organic compound-containing water vapor K arrives due to the opening of the first supply port 15A. However, it may drop suddenly when the supply port is closed. Since the change clearly appears as the furnace temperature of the combustion furnace 13, the temperature in the combustion furnace 13 is continuously measured by the temperature sensor 24 in the combustion furnace. When the detection is detected, the heat load applied to the combustion furnace 13 can be further reduced by finely adjusting the supply amount to be increased.

Even if this embodiment is changed in several points, the effect of the present invention can be obtained.
In the above embodiment, the contained water vapor temperature sensor 25 provided in the vicinity of the outlet 16 may be provided at a location slightly entering the contained steam pipe 21 from the outlet 16. However, compared with the case where it is provided in the contained steam pipe 21, the adjustment range of the set temperature is increased according to the size of the adsorption tower and the amount of the adsorbent. When the above configuration is provided in the pipe closer to the combustion furnace 13, the adjustment width depending on the size of the adsorption tower 11 can be reduced.

  Moreover, the arrival of the organic compound-containing water vapor can be detected as a result of an increase in the combustion temperature also by the measurement of the temperature sensor 24 in the combustion furnace provided in the combustion furnace 13 without using the water vapor temperature sensor 25. However, in that case, since the temperature of the combustion furnace 13 has already risen, even if the opening adjustment of the supply ports 15 </ b> A to 15 </ b> D is performed thereafter, it takes too much time for the adjustment result to reach the combustion furnace 13. For this reason, the adjustment when the temperature sensor 24 in the combustion furnace 13 deviates from a predetermined temperature range is preferably performed by adjusting the fuel D from the fuel supply port 22 directly connected to the combustion furnace 13. .

  Further, after the desorption in one adsorption tower 11a is finished and until the desorption in the other adsorption tower 11b is started, the desorption water vapor F is returned to the heat exchanger 14 by using the branch 33 and is in a standby state. It may be.

  Further, when the supply port 15A is opened, the opening 39 is opened, and the opening 39 is closed after the first desorption peak has elapsed, thereby further leveling the first maximum value or the minimum value. be able to. Furthermore, instead of opening the opening 39, the amount of desorption water vapor F generated by the heat exchanger 14 may be temporarily reduced, but this is not preferable because the load on the heat exchanger 14 increases.

  Next, 2nd embodiment which changed the structure of the adsorption tower 11 is described using FIG. In the adsorption tower 51 for performing adsorption and desorption in this embodiment, a cylindrical adsorption layer 53 is divided into three 120 degrees by three partitions 52, and each partitioned region 54 is independent. It is. In each of the regions 54A to 54C, supply ports 55A and 55B, supply ports 55C and 55D, and supply ports 55E and 55F are provided in two upper and lower stages. A supply port 55G is provided at the bottom of the adsorption tower 11 below the adsorption layer 53. The partition 52 does not reach either the upper side or the lower side of the adsorption layer 53. Although not shown in the figure, each supply port is provided with a valve for open / close control.

  The inlet 17 for introducing the organic compound-containing gas A, the outlet 18 for discharging the treated gas B, and the outlet 16 are provided in the same manner as the adsorption tower 11. Although not shown in the drawing, the configurations of the combustion furnace 13 and the heat exchanger 14 are the same, and the configurations of the pipes are also the same. Also, the same operation method is possible in which two adsorption towers 51 having the same configuration are provided, and adsorption is performed on the other side while desorption is performed on the one side.

  When the organic compound-containing gas A is adsorbed by the adsorption tower 51 according to this embodiment, the organic compound-containing gas A introduced from the inlet 17 is divided into each of the regions 54A to 54C arranged in parallel. Passed and adsorbed, discharged as processed gas B.

  The process of obtaining the desorption water vapor F having a sufficiently high temperature in the combustion furnace 13 and the heat exchanger 14 in the preparation stage of the desorption process is the same as that of the first embodiment. In starting the desorption, one of the supply ports 55A, 55C, and 55E on the side close to the outlet 16 in any one of the three regions 54A to 54C is selected and opened. If the supply port 55A is opened, the supply port to be opened next may be the supply port 55B located below in the same region 54A, or the supply on the side close to the outlet 16 in one of the other regions 54B, 54C. Either the mouth 55C or 55E may be used. When the second supply port is opened, the first opened supply port 55A remains open, and thus is included in the desorbed organic compound-containing water vapor as in the first embodiment. The maximum value of the amount of volatile organic compounds can be leveled.

  Then, the desorption water vapor F can be efficiently distributed by closing the supply port 55A opened first, in accordance with the timing of opening the third supply port. The timing can also be set as in the first embodiment.

  In another embodiment, the second supply port and the third supply port are in different regions 54A to 54C from the first supply port, so that the fourth supply port is provided. They shall not be closed until the mouth is opened. Then, the supply port opened first is closed, the supply port in the same area as the first supply port is opened as the fourth supply port, and then the second supply port is closed and the same. By repeatedly opening the supply port in the area as the fifth, the desorption can be performed uniformly in each of the areas 54A to 54C.

  Hereinafter, the supply ports 55A to 55F may be opened in any order as long as the condition is that the lower supply port opens after the upper supply port in the same region. For example, 55A, 55B, 55C, 55D, 55E, and 55F may be in the order of detaching each region in sequence, or the upper supply port such as 55A, 55C, 55E, 55B, 55D, and 55F may be opened first. Therefore, the order of opening the lower supply ports may be used, or an irregular order combining them may be implemented.

  After all the supply ports 55A to 55F are opened, finally, the supply port 55G provided at the bottom of the adsorption tower 51 is opened. The desorption water vapor | steam F supplied here passes through all the area | regions 54A-54C, and performs desorption of finishing.

  Furthermore, after a certain period of time has elapsed since the supply port 55G is opened, all the supply ports may be opened to ensure thorough desorption. When such full opening is performed after 15 minutes or more have passed since the last supply port 15G is opened, finishing can be performed after sufficient desorption by the last supply port 55G. On the other hand, when it is performed after 30 minutes, it takes too much time for the entire desorption process, which is not preferable.

  This embodiment can be implemented with further changes in details. The partition 52 may partition not only the inside of the adsorption layer 53 but also the bottom part below the adsorption layer 53. This is desirable in terms of desorption efficiency. However, there is a demerit that the number of members of the adsorption tower 51 increases and the control becomes complicated.

  Also, in order to simplify the structure, the supply ports provided in the respective regions 54A to 54C are not multi-staged, but only one stage, the supply ports in the respective regions are opened in order, and finally the supply port at the bottom is opened. Good. In the case where the adsorbent in the adsorption tower 51 is relatively small, such a configuration can be sufficiently implemented. However, in order to ensure the detachment of each region, it is better not to omit the supply port opened at the bottom provided at the bottom.

  Furthermore, the adsorption layer 53 can be implemented not by three but also by two or four. However, if the number of divisions increases too much, the desorption efficiency decreases.

  Next, 3rd embodiment which changed the structure of the adsorption tower 11 is described using FIG. In the adsorption tower 57 that performs adsorption and desorption in this embodiment, the adsorption layer 53 is divided into three parts by three partitions 52, and the partitioned regions 54A to 54C are formed as in the second embodiment. be independent. The difference from the second embodiment is that there is one supply port (58A to 58C) provided in each of the regions 54A to 54C. Apart from these, a supply port 58D is provided at the bottom of the adsorption tower 11 below the adsorption layer 53, and the other configuration is the same as that of the adsorption tower 51. Compared to the adsorption tower 51 that executes the second embodiment, the configuration like the adsorption tower 57 is applied when the scale is relatively small.

  In carrying out the desorption, as in the first and second embodiments, first, the first supply port 58A is opened, and the organic compound-containing water vapor derived from the first supply port 58A is left open. Before K reaches the combustion furnace, the second supply port 58B is opened. The third supply port 58C is opened after a certain period of time has elapsed from the opening of the second supply port 58B, before the organic compound-containing water vapor derived from the supply port 58B reaches the combustion furnace, and the timing is adjusted accordingly. The first supply port 58A is closed. That is, the supply ports 58A to 58C in each region are opened in order, and the fourth supply port 58D provided at the bottom of the adsorption tower 57 is finally opened. The timing at which the fourth supply port 58D is opened is after a predetermined time has elapsed since the third supply port 58C was opened, and before the organic compound-containing water vapor K derived from the supply port 58C reaches the combustion furnace. What is necessary is just to carry out with the timing which closes the 2nd supply port 58B. Further, the third supply port 58C is closed at the same timing, and the entire amount of water vapor is supplied from the fourth supply port 58D, so that all the regions 54A to 54C are thoroughly attached and detached.

  Among these first to third embodiments, when the adsorption layer cross-sectional area is large, efficiency is improved by partitioning and desorbing in parallel as in the second and third embodiments. On the other hand, in terms of thorough desorption, the first embodiment is superior in that the water vapor supplied from the next supply port is further desorbed even in the region of the adsorption layer desorbed by the previous supply port.

  Hereinafter, the present invention will be described more specifically by way of examples. First, the experimental apparatus will be described. In the experiment, an adsorption tower having an adsorption tower size: φ68 (inner diameter) × 700H, a packed part: φ68 × 600H (volume: 2.18 L), and an activated carbon weight: 1000 g (Shirakaba S2x 4/6) is used. Two types of experiments were conducted by changing the positions of the supply port and the supply port. The configuration other than the adsorption tower is the same as in FIG.

<Experiment method>
A gas containing toluene as a volatile organic compound was passed through an adsorption tower in advance, and the toluene was sufficiently adsorbed on activated carbon as an adsorbent. After completion of the adsorption, desorption water vapor was introduced from the supply port, and organic compound-containing water vapor containing toluene was discharged from the outlet at the top of the tower. A part of this water vapor was collected in a pipe provided between the outlet and the combustion furnace, passed through a cooling pipe, and condensed and recovered. The collection was performed every minute, the toluene layer of the collected agglomerated liquid was allowed to stand and separated, the volume was measured, and the change over time in the amount of desorbed toluene was measured.

Example 1
A steam supply port was provided at the center of the side surface and the bottom surface of 160 mm and 350 mm from the top surface of the adsorption tower, and an outlet was provided at the center of the top surface of the adsorption tower. That is, in the form of FIG. 1, the supply port is one stage less. The following procedure was carried out with the upper supply port in the layer being A, the lower supply port in the layer being B, and the bottom supply port being C.
(1) A is opened, and 1.68 kg / h desorption water vapor is allowed to flow. B and C are closed.
(2) After 5.5 minutes, B is opened, and 0.84 kg / h desorption water vapor is passed through A and B.
(3) After 12 minutes, A is closed to open C, and 0.84 kg / h of desorption water vapor is allowed to flow through B and C, respectively.
(4) After 30 minutes, B is closed and 1.68 kg / h desorption water vapor is allowed to flow through C.
The result is shown in FIG.

(Example 2)
In the same configuration as in Example 1, the opening of B was changed after 6 minutes, and the opening of C and the closing of A were changed after 15 minutes. The result is shown in FIG.

(Comparative example)
Measurement was performed by supplying 1.68 kg / h of desorption water vapor from the start to the end of the desorption without using a multi-stage supply port and only the one provided at the bottom of the adsorption tower. The result is shown in FIG.

(result)
In the comparative example, the discharge amount showed a maximum of 27 g / min in 12 minutes after the start of desorption, and then dropped rapidly, but in Example 1, the discharge amount showed a maximum of about 4 g / min throughout the desorption process, It can be seen that it is stable at almost the same value throughout the desorption process. In Example 2, the maximum was about 7 g / min, and leveling was performed in substantially the same manner as Example 1 except for the first timing.

It is considered that the following phenomenon occurs at each timing of the embodiment.
(1) A release A release increases the amount of desorption rapidly. In addition, by opening from A close to the outlet, an increase in the desorption amount is started earlier than in the prior art.
(2) A release + B release By continuously releasing B, water vapor from A is halved, and the peak of the desorption amount is greatly reduced compared to the conventional case. Further, since there is a time lag in which the solvent desorbed by the B release reaches the outlet (before the combustion furnace), the latter half of the whole tends to decrease.
(3) B opening + C opening Since the solvent desorbed by B opening reaches, the discharge amount increases, but after exceeding the peak, it tends to decrease as in (2).
(4) C open Same as (3).

  The difference between the first maximum value in Example 1 and Example 2 is that the peak was suppressed in Example 1 because the amount of desorption water vapor to the supply port A was halved immediately before the maximum value occurred. Conceivable.

11, 11a, 11b Adsorption tower 12 Adsorption layer 13 Combustion furnace 14 Heat exchanger 15A, 15B, 15C, 15D Supply port 16 Outlet 17 Inlet 18 Outlet 20 Perforated plate 21 Containing steam piping 22 Fuel supply port 23 Containing steam supply Port 24 Combustion furnace temperature sensor 25 Contained water vapor temperature sensor 31 Circulation port 32 Desorption water vapor supply path 33 Branch (to circulation path)
34 Circulation path 35 Branch (to air discharge)
36 Water vapor temperature sensor 38 Water supply port 39 Opening port 40 Branch (Adsorption tower two minutes)
51 Adsorption tower 52 Partition 53 Adsorption layers 54A-54C Regions 55A-55G Supply port 57 Adsorption towers 58A-58D Supply port A Volatile organic compound-containing gas B Processed gas D Fuel E Water F Desorption water vapor K Organic compound-containing water vapor T _Time lag from start of _rag supply to first detection T _open0 Time period for opening the second supply port T _open1 Time from opening of the first supply port to opening of the second supply port

Claims (6)

A gas containing a volatile organic compound is introduced into an adsorption tower having an adsorption layer filled with an adsorbent that adsorbs the volatile organic compound, and the content is reduced by adsorbing the volatile organic compound to the adsorbent. After exhausting the treated gas, the desorption water vapor generated by heating with heat generated in the combustion furnace is introduced into the adsorption tower to desorb volatile organic compounds from the adsorbent, and the desorbed organic compound-containing water vapor is removed. The operation method of the adsorption tower, which is discharged from the outlet provided on one end side than all the adsorption layers, introduced into the combustion furnace and burned,
The adsorption tower is provided with a plurality of desorption water vapor supply ports generated by heating with heat generated in one or a group of combustion furnaces, at least at locations away from the end of the adsorption layer on the outlet side. And
At least one of the supply ports introduces the desorption water vapor directly into the adsorption layer,
In opening each supply port,
If there are a plurality of supply ports sharing a part of the path in the adsorption layer to the outlet, the supply port close to the outlet is opened first,
The supply port to be opened next is opened at least before closing the supply port opened immediately before,
When closing each supply port, it is characterized in that it is performed after a lapse of a certain time since opening the supply port opened immediately before,
Operation method of volatile organic compound adsorption tower.   2. The volatilization according to claim 1, wherein one of the two supply ports that are open at the same time is closed in accordance with a timing of opening a supply port that is opened next. To use a functional organic compound adsorption tower.   3. The method for operating a volatile organic compound adsorption tower according to claim 1, wherein all the supply ports that have been once closed are opened after the supply ports that are finally opened are opened. The timing at which the third and subsequent supply ports are opened is two minutes or more after the previous supply port is opened, and the organic compound-containing water vapor derived from the previous supply port is removed from the combustion furnace. Before reaching
The operation method of the volatile organic compound adsorption tower according to any one of claims 1 to 3 , wherein the timing of closing each supply port is matched with the opening of the supply port that is opened two times later. There are a plurality of paths in the adsorption layer to the outlet, and there is a supply port for introducing the desorption water vapor on each path corresponding to at least the number of paths,
The inside of the adsorption layer is partitioned in parallel, and there is a supply port for introducing the desorption water vapor only in each partitioned region,
After opening one supply port, if there is a dedicated supply port for the same area as the supply port, the supply port is opened with priority over the other supply ports. After all of the dedicated supply ports have been opened, open the dedicated supply ports for other routes.
The operation method of the volatile organic compound adsorption tower in any one of Claims 1 thru | or 4 . The volatilization according to any one of claims 1 to 5 , wherein a supply port is provided at a position on the other end side of all the adsorption layers of the adsorption tower and is opened at the end of all the supply ports. To use a functional organic compound adsorption tower.

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