JP4280828B2 - Gas replacement type occlusion discharge NOx treatment method and apparatus - Google Patents

Description

  The present invention relates to a gas replacement type occlusion discharge NOx treatment method in which NOx such as polluted air is adsorbed on an adsorbent, and then the desorbed NOx is decomposed by discharge, and an apparatus for carrying out the method.

  When performing discharge treatment of NOx pollutant gas, if oxygen is contained, NOx decomposition reaction due to discharge is significantly inhibited. For example, when about 300 ppm of NO is discharged at an oxygen concentration of about 3% diluted with nitrogen, only the oxidation reaction of NOx proceeds, and the NOx decomposition reaction hardly proceeds.

Since the oxidation reaction requires treatment of by-products such as nitric acid, it is desirable to cause a NOx decomposition (reduction) reaction by removing oxygen. As a method for this, when NOx is once adsorbed on the adsorbent and this NOx is desorbed from the adsorbent (hereinafter referred to as “desorption”), the flow gas is switched to nitrogen gas, and the flow gas composition of the discharge field is changed to N ₂ / NOx. A method of performing discharge NOx decomposition by using gas has been proposed (Non-patent Document 1 below).

  In this method, since the production energy of nitrogen gas is large, it is necessary to minimize the required amount of nitrogen gas. For this reason, a method has been devised in which nitrogen gas is circulated between the adsorbent-filled container and the discharge container, and the nitrogen gas is circulated and used until the increase in oxygen concentration accompanying the discharge treatment reaches an allowable limit (patent). 3455815 specification). However, with this method, it is necessary to renew the nitrogen gas at a constant frequency, which increases the amount of nitrogen gas used and makes the processing operation troublesome.

As a method for solving this point, the present inventors also proposed a method in which oxygen generated by decomposition of NOx is removed by an oxygen remover and the oxygen remover is regenerated by hydrogen in the above circulation method. (Japanese Patent Application No. 2003-411110). In this method, since it is not necessary to renew the desorption gas, a high concentration NOx-containing nitrogen gas can be used as a circulation gas at the time of desorption. In the discharge process, NOx equivalent to desorption NOx is only decomposed, so that the NOx concentration is kept high even at the end of discharge. As a result, the discharge process is always performed for high concentration NOx, and the energy efficiency of the discharge process is improved.
Patent No. 3455815 specification Japanese Patent Application No. 2003-411110 N. Goto, S. Kudo, H. Motoyama & S. Ohyama, Japanese Journal of Applied Physics, 41, L64 (2002)

(1) Residual oxygen at the end of adsorption As described above, many researches and developments have been made on measures to avoid the adverse effects of oxygen as a by-product accompanying NOx decomposition due to discharge. However, after completion of the adsorption operation, when the desorption operation is started, the gas remaining in the NOx adsorbent filling container contains oxygen at the stage of switching the flow gas to nitrogen gas or N ₂ / NOx mixed gas. Measures against this oxygen are necessary.

  Such influence of residual oxygen does not cause a problem when the filling rate of the adsorbent filled in the NOx adsorbent filling container is sufficiently high. This is because, when the filling rate is high, the amount of residual oxygen is sufficiently smaller than the total amount of adsorbed NOx, so in comparison with the oxygen produced during NOx decomposition, residual oxygen can be ignored as an oxygen source. It is.

  However, when the filling rate of the adsorbent is increased, the pressure loss in the gas flow increases, so that there is a problem that the pump power increases in order to meet the demand for processing a large amount of gas at high speed. In order to suppress such an increase in pressure loss, practically, the adsorbent is carried on a honeycomb-like ceramic or the like.

  When such a honeycomb-shaped adsorbent is used, pressure loss can be reduced, but at the same time, the adsorbent filling rate decreases. As the filling rate decreases, the amount of residual oxygen at the time of gas switching increases and may exceed the total amount of adsorbed NOx. In particular, when treating NOx-contaminated air, in addition to the low NOx concentration, the adsorption amount remains small, and because the oxygen concentration is high, the residual oxygen is calculated to greatly exceed the adsorption NOx amount, and some measures are taken. It is necessary to take

 As a countermeasure, there is a method of releasing the residual gas in the NOx adsorbent filling container to the outside by nitrogen gas purge at the time of gas switching. However, in this method, nitrogen gas outflow loss is unavoidable in the gas purge, which increases the processing cost. Therefore, the present invention provides a method for removing residual oxygen without causing such nitrogen gas outflow loss.

(2) Residual useful gas at the end of desorption As a similar problem, N ₂ / O ₂ mixed gas or N ₂ / NOx mixed gas remains in the NOx adsorbent filled container at the end of desorption and discharge. . These residual gases are useful gases for decomposing NOx by electric discharge, and discharging the residual gases to the outside when switching to the adsorption operation increases processing costs. In addition, releasing the N ₂ / NOx mixed gas to the outside environment directly leads to a decrease in performance as a NOx removing device. The NOx remaining in the NOx adsorbent-filled container may be re-adsorbed to the adsorbent, but may be difficult to re-adsorb in the absence of oxygen. In addition, when it is re-adsorbed, the NOx adsorption amount in the next stage is reduced, resulting in a reduction in processing performance. Therefore, it is desirable that the residual gas at the end of desorption is efficiently recovered and reused as a useful gas.

  As described above, it is an important issue to take effective measures against the gas remaining in the NOx adsorbent-filled container during the switching operation between adsorption and desorption. Therefore, the present invention aims to remove residual oxygen without incurring nitrogen gas outflow loss as described above, and to recover and reuse the residual gas in the NOx adsorbent-filled container through a series of replacement operations. And

  In order to solve the above problems, the gas replacement occlusion discharge NOx treatment method according to the present invention includes a first gas container filled with carbon dioxide gas above a NOx adsorbent filled container filled with NOx adsorbent and a nitrogen gas below. The NOx adsorbent filling container, the first gas container, and the second gas container are filled with the NOx adsorbent by two connecting pipes each provided with an open / close valve. Connected to the NOx adsorbent filling container, NOx is adsorbed to NOx adsorbent by circulating NOx pollutant gas in the NOx adsorbent filling container, and at the end of the adsorption operation, carbon dioxide in the upper first gas container is The NOx adsorbent filling container is caused to flow downward to replace the adsorbed gas in the NOx adsorbent filling container, the carbon dioxide gas in the NOx adsorbent filling container is caused to flow down to the second gas container below, and the first Replace with nitrogen gas in 2 gas container and fill with NOx adsorbent NOx adsorbed on the NOx adsorbent by filling with nitrogen gas inside and then depressurizing or heating, and decomposing NOx by circulating NOx desorbed in the NOx adsorbent filled container between the discharge container After that, the positions of the upper and lower first gas containers and the second gas container are reversed, and the carbon dioxide gas in the upper second gas container is allowed to flow downward in the NOx adsorbent filling container to be in the NOx adsorbent filling container. The carbon dioxide gas in the NOx adsorbent filling container is caused to flow down to the first gas container below, and the adsorbed gas in the first gas container is substituted into the NOx adsorbent filling container. A series of operations of filling the adsorbed gas, circulating NOx pollutant gas, and performing the adsorption operation is repeated until the oxygen concentration in the nitrogen gas increases and the efficiency of the discharge treatment decreases, and then the nitrogen treatment The gas is changed.

  Further, another gas replacement type occlusion discharge NOx treatment method according to the present invention is the gas substitution type occlusion discharge NOx treatment method, wherein the volume inside the first gas container and the second gas container is set in the NOx adsorbent filling container. It is set equal to the void volume.

Further, another gas replacement type occlusion discharge NOx treatment method according to the present invention is the gas substitution type occlusion discharge NOx treatment method, wherein the filling gas in the gas container located below is N ₂ / NOx mixed gas, Oxygen scavenger filling container is installed in the first stage, NOx decomposition by discharge is performed to the same extent as the desorption amount from the NOx adsorbent, and a series of operations of NOx adsorption, gas replacement, NOx desorption, discharge treatment, gas replacement, NOx adsorption Is repeated until the oxygen scavenger is deactivated, and thereafter the oxygen scavenger is exchanged or regenerated.

  Further, another gas replacement type occlusion discharge NOx treatment method according to the present invention is the gas substitution type occlusion discharge NOx treatment method, wherein two of the connecting pipes connecting the upper and lower gas containers and the NOx adsorbent filling container are used. , One is inserted into the gas container, the tube is inserted into the container from the NOx adsorbent-filled container side facing the other connecting pipe, and the inner tubes in the upper and lower gas containers and their connections Attach an electric heater to at least one of the pipe and the inner tube that goes upward in the NOx adsorbent-filled container and the corresponding connecting pipe on the gas container side, and heat the pipe that is used as the rising pipe during the gas replacement operation. By doing so, convection is promoted.

  In addition, the gas displacement occlusion discharge NOx treatment apparatus according to the present invention has a first gas container disposed above a NOx adsorbent filling container filled with a NOx adsorbent therein, and a second gas container disposed below the NOx adsorbent. The NOx adsorption container is connected to the first gas container and the second gas container so that the NOx adsorbent filling container can be turned upside down by two connecting pipes each provided with an on-off valve. A NOx-contaminating gas is circulated in the agent-filled container so that NOx can be adsorbed to the NOx adsorbent, the first gas container is filled with carbon dioxide gas, the second gas container is filled with nitrogen gas, The NOx adsorbent filling container and the discharge container are connected via an on-off valve, and the gas in the first gas container and the NOx adsorbent filling container, and the gas in the NOx adsorbent filling container and the second gas container are connected. They are provided so that they can be replaced in order.

  Further, another gas replacement type occlusion discharge NOx processing apparatus according to the present invention is the gas replacement type occlusion discharge NOx processing apparatus, wherein the volume inside the first gas container and the second gas container is the inside of the NOx adsorbent filling container. It is set equal to the void volume.

Further, another gas replacement type occlusion discharge NOx processing apparatus according to the present invention is the gas replacement type occlusion discharge NOx processing apparatus, wherein the filling gas in the gas container located below is N ₂ / NOx mixed gas, An oxygen remover-filled container is provided in the previous stage, and a series of operations including NOx adsorption, gas replacement, NOx desorption, discharge treatment, gas replacement, and NOx adsorption are repeated until the oxygen remover is deactivated.

  Further, another gas replacement type occlusion discharge NOx processing apparatus according to the present invention is the gas replacement type occlusion discharge NOx processing apparatus, wherein two of the connecting pipes connecting the upper and lower gas containers and the NOx adsorbent filling container are used. , One is inserted into the gas container, the tube is inserted into the container from the NOx adsorbent-filled container side facing the other connecting pipe, and the inner tubes in the upper and lower gas containers and their connections A convection-promoting electric heater is attached to at least one of the pipe, the inner insertion pipe extending upward in the NOx adsorbent filling container, and the corresponding connection pipe on the gas container side.

Since the present invention is configured as described above, the following effects can be obtained.
(1) Removal of residual oxygen at the end of adsorption
Oxygen remaining in the NOx adsorbent-filled container at the end of NOx adsorption can be eliminated without causing loss of useful gas. As a result, the required amount of nitrogen gas can be reduced, the energy efficiency of the discharge treatment can be improved, and the load on the oxygen removing device can be reduced.

(2) Recovery and reuse of residual gas at the end of desorption
The gas remaining in the NOx adsorbent-filled container at the end of the NOx desorption / discharge process can be recovered as a useful gas and reused. As a result, the required amount of nitrogen gas or N ₂ / NOx mixed gas to be circulated at the time of desorption can be reduced. When N ₂ / NOx mixed gas is circulated, NOx removal performance is improved by preventing external release and re-adsorption of N ₂ / NOx mixed gas remaining in the NOx adsorbent filling container at the end of desorption. Has the effect of

(3) Gas replacement time shortening During gas replacement, a tube used as a riser is heated to induce an updraft and promote convection. Thereby, the time required for gas replacement can be greatly shortened.
There are many advantages.

  In the present invention, gas containers are installed above and below a container filled with NOx adsorbent through two on-off valves, the upper gas container is filled with carbon dioxide gas, and the lower gas container is filled with nitrogen gas. The structure is such that the positional relationship between the upper and lower gas containers can be reversed by filling and rotating. The volume inside the upper and lower gas containers is assumed to be equal to the void volume in the NOx adsorbent-filled container. After NOx is adsorbed by circulating NOx pollutant gas through the NOx adsorbent filling container, the carbon dioxide gas in the upper gas container is replaced downward into the NOx adsorbent filling container at the end of the adsorption operation, and then the carbon dioxide gas is replaced. Nitrogen gas is filled into the NOx adsorbent filling container by substituting the lower gas container. Thereafter, NOx is desorbed by depressurization or heating, and NOx is decomposed by circulating between the discharge vessel. At the same time, the positional relationship between the upper and lower gas containers is reversed by a rotating operation. After completion of the desorption / discharge process, the carbon dioxide in the upper gas container is replaced downward into the NOx adsorbent filling container, and then the carbon dioxide is replaced with the lower gas container. As a result, the NOx adsorbent filling container is filled with the adsorbed gas, and the NOx contamination gas is circulated again to start the adsorption operation. The above-described series of operations is repeated until the oxygen concentration in the nitrogen gas increases and the efficiency of the discharge treatment decreases, and thereafter, the gas replacement occlusion discharge NOx treatment method or method thereof is characterized in that the nitrogen gas is replaced. This is an apparatus to be implemented.

Further, the gas substitution type occlusion discharge NOx treatment method or the apparatus for carrying out the method according to the present invention is the above-mentioned gas substitution type occlusion discharge NOx treatment method and apparatus, wherein the filling gas in the lower gas container is mixed with N ₂ / NOx. The gas is filled with an oxygen remover-filled container in the front stage of the discharge vessel, and NOx decomposition by discharge is kept at the same level as the amount of desorption from the NOx adsorbent, and NOx adsorption / gas replacement / NOx desorption / discharge treatment / gas replacement -A series of operations of NOx adsorption ... is repeated until the oxygen scavenger is deactivated, and then the oxygen scavenger is exchanged or regenerated.

  In addition, the gas replacement type occlusion discharge NOx treatment method or the apparatus for carrying out the method according to the present invention connects the upper and lower gas containers and the NOx adsorbent filling container in the gas substitution type occlusion discharge NOx treatment method and apparatus. One of the two connecting pipes is inserted into the gas container. A tube is inserted into the container from the connection port on the side of the NOx adsorbent-filled container facing the other connection pipe. Attach an electric heater to the inner intubation in the upper and lower gas containers and their connection pipes, and the upper intubation pipe in the NOx adsorbent filling container, and the corresponding connection pipe on the gas container side, during the gas replacement operation, When used as riser tubes, these tubes are heated to promote convection and reduce the time required for gas replacement.

  FIG. 1A is a cross-sectional view of a NOx adsorbent-filled container 11 and a gas replacement apparatus connected to the NOx adsorbent-filled container 11 which is the center of an apparatus for carrying out the gas replacement occlusion discharge NOx treatment method according to the present invention. A description will be given based on the longitudinal sectional view of b). The NOx adsorbent filling container 11 has a cylindrical shape, and the NOx adsorbent 12 is filled in the container, and a gas to be treated such as an air pollutant gas flows from one end of the cylindrical container, and the other side. In the meantime, NOx is adsorbed by the NOx adsorbent 12, and the NOx is desorbed as described later. This NOx adsorbent-filled container 11 is cylindrical and has a central axis installed horizontally.

  In the state shown in FIG. 1, the first gas container 9 is installed on the upper side of the NOx adsorbent filling container 11 through the on-off valves 1 and 2, and the second gas container is on the lower side through the on-off valves 3 and 4. 10 is installed. The first gas container 9, the second gas container 10 and the release valves 1 to 4 are combined with a cylindrical cover 13 that covers the outer periphery of the NOx adsorbent filling container 11, and are configured integrally. The outer periphery of the container 11 can be integrally rotated.

  A rotatable gas seal 14 is provided between the cylindrical cover 13 and the outer periphery of the NOx adsorbent filling container 11. The rotationally movable gas seal 14 maintains the airtightness of the pipe connection portion between the first gas container 9 and the second gas container 10 and the NOx adsorbent filling container 11 and enables a smooth rotation operation. Thereby, the 1st gas container 9 and the 2nd gas container 10 can rotate the outer periphery of NOx adsorbent filling container 11, maintaining airtightness with the external environment. By such a rotating operation, the positional relationship between the gas containers 9 and 10 can be reversed upside down.

  The connecting pipe 15 provided with the on-off valve 2 and the connecting pipe 16 provided with the on-off valve 4 are respectively inserted deep inside the first gas container 9 and the second gas container 10. In the NOx adsorbent filling container 11, the bent pipe 17 and the bent pipe 18 are disposed at positions facing the connection pipes of the on-off valve 1 and the on-off valve 3 so that the bent pipe 17 and the bent pipe 18 do not interfere with each other. It is inserted deep inside.

  The internal volumes of the first gas container 9 and the second gas container 10 are set to be the same as the void volume excluding the volume of the NOx adsorbent in the NOx adsorbent filling container 11.

 FIG. 2 shows an apparatus capable of carrying out the gas replacement occlusion discharge NOx treatment method according to the present invention by combining the above apparatus with the discharge treatment apparatus. Stated in order.

(1) Initial state As shown in FIG. 1 and FIG. 2 (a), the first gas container 9, the on-off valve 1 and the on-off valve 2 are positioned above the NOx adsorbent filling container 11. The second gas container 10, the on-off valve 3, and the on-off valve 4 are positioned below the NOx adsorbent filling container 11. The first gas container 9 is filled with carbon dioxide gas, and the second gas container 10 is filled with nitrogen gas. The discharge vessel 19 and the vacuum pump 20 are also filled with nitrogen gas. At this time, the on-off valves 1 to 8 are closed.

(2) Adsorption By opening the on-off valve 5 and on-off valve 6 and allowing NOx contaminated gas to flow through the NOx adsorbent filling container 11, NOx is adsorbed and the clean gas is exhausted. After the amount of adsorption reaches a predetermined level, the on-off valve 5 and the on-off valve 6 are closed to end the adsorption operation.

(3) Gas replacement Open the on-off valve 1 and the on-off valve 2. The carbon dioxide gas in the first gas container 9 is supplied to the lower part of the NOx adsorbent filling container 11 through the on-off valve 1 by natural convection, and at the same time, the adsorbed gas remaining in the NOx adsorbent filling container 11 is Both gases are replaced by being led into the first gas container 9 through the on-off valve 2. After the replacement, the on-off valve 1 and the on-off valve 2 are closed, and the on-off valve 3 and the on-off valve 4 are opened. Then, the carbon dioxide gas in the NOx adsorbent-filled container 11 flows down to the second gas container through the on-off valve 4, and at the same time, nitrogen gas in the second gas container 10 (N ₂ / O ₂ from the second round). Gas)) flows upwardly into the NOx adsorbent filling container 13 through the on-off valve 3, and both gases are replaced. After this replacement is completed, the on-off valve 3 and the on-off valve 4 are closed.

(4) Desorption & Discharge Treatment The on-off valve 7 and on-off valve 8 are opened, the vacuum pump 20 is started, and gas is circulated between the NOx adsorbent filling container 11 and the discharge container 19. At this time, the inside of the NOx adsorbent filling container 11 and the discharge container 19 is depressurized by the operation of the vacuum pump 20. By adjusting the opening degree of the on-off valve 8, the exhaust pressure of the vacuum pump 20 is reduced and the reduced pressure in the NOx adsorbent filling container 11 is maintained. As the pressure is reduced, NOx is desorbed from the adsorbent 12. At the same time, power is supplied from a power source (not shown) to the discharge vessel 19 to start discharging. After most of the NOx desorbed by decompression is decomposed by discharge, the discharge is stopped and the vacuum pump 20 is also stopped. Since oxygen is generated as a by-product of NOx decomposition due to discharge, the treated N2 / O2 gas remains in the NOx adsorbent-filled container 11 and the discharge container 19. However, as the above steps (2) to (5) are repeated, the oxygen concentration increases, and when the concentration exceeds about 1%, the efficiency of the discharge treatment decreases. In this case, a new NOx adsorbent-filled container is used. 11 or the gas inside the discharge vessel 19 is replaced with nitrogen gas. Thereafter, the on-off valve 7 and the on-off valve 8 are closed.

(5) Gas replacement Thereafter, the first gas container 9 and the second gas container 10 on the outer periphery of the NOx adsorbent filling container 11 are integrally rotated, and the positional relationship between the two is switched up and down as shown in FIG. As a result, the second gas container 10 filled with carbon dioxide gas moves upward, and the first gas container 9 filled with adsorbed gas moves downward.

By opening the on-off valve 3 and the on-off valve 4, the carbon dioxide gas in the second gas container 10 descends into the NOx adsorbent filling container 11 by natural convection, and at the same time, remains in the NOx adsorbent filling container 11. The treated N ₂ / O ₂ gas rises into the second gas container 10 and both gases are replaced. After this replacement is completed, the on-off valve 3 and the on-off valve 4 are closed, and the on-off valve 1 and the on-off valve 2 are opened. Then, the carbon dioxide gas in the NOx adsorbent filling container 11 falls to the first gas container 9, and at the same time, the adsorbed gas in the first gas container 9 rises into the NOx adsorbent filling container 11 and both. The gas is replaced. After this replacement is completed, the on-off valve 1 and the on-off valve 2 are closed.

Next, the first gas container 9 and the second gas container 10 arranged on the outer periphery of the NOx adsorbent filling container 11 are integrally rotated, and the positional relationship between the two is exchanged as shown in FIG. As a result, the first gas container 9 filled with carbon dioxide gas moves upward, and the second gas container 10 filled with treated N ₂ / O ₂ gas moves downward.
Thereafter, the procedure returns to the suction operation (2) and the respective steps are repeated.

  The above describes the method of renewing the circulating gas to nitrogen gas when the oxygen concentration increases with the discharge treatment, but separately from this, the inventors previously filed the discharge It is also possible to apply a method in which an oxygen removing agent is installed in the stage before sending gas to the container 19 to remove oxygen. The configuration of the apparatus in this case is the same as that of Example 1 except that an oxygen removing agent filling container is installed in the front stage of the discharge container 19 of FIG. In this method, since the oxygen concentration does not increase, it is not necessary to update the circulating gas. For this reason, it becomes possible to use nitrogen gas containing high concentration NOx as the circulating gas at the time of desorption. Then, the discharge process is performed on the high concentration NOx, and the energy efficiency of the discharge process is improved.

Regarding the operation procedure, the difference from the first embodiment is as follows.
(1) Initial state The inside of the second gas container, the oxygen removing agent filling container, the discharge container, and the vacuum pump are filled with N ₂ / NOx mixed gas.

(3) Gas replacement The NO 2 adsorbent-filled container 11 is filled with the N ₂ / NOx mixed gas by a series of replacement operations.

(4) Desorption & discharge treatment The discharge treatment is stopped at the stage where NOx equivalent to the desorbed NOx is decomposed. As a by-product of the NOx degradation due to discharge, oxygen is generated, because it is removed by the oxygen scavenger, within NOx adsorbent filling container 13 and the discharge vessel 19, as in the case of discharge starting N ₂ / NOx gas Remains. However, when the capacity of the oxygen scavenger becomes saturated as the procedures (1) to (4) are repeated, the oxygen scavenger is replaced or the oxygen scavenger is regenerated.

(5) Gas replacement The N ₂ / NOx mixed gas is evacuated into the second gas container 10 by a series of replacement operations.

  In the present invention, gas replacement is performed by natural convection, but in the above embodiment, the start of convection is triggered by the difference in gas weight inside the rising and lowering pipes due to particle diffusion. It becomes. Therefore, it may take time to start convection. Further, after the start of convection, when the driving force of convection is insufficient, the convection speed is slow and it takes time for gas replacement. In order to increase the driving force of convection, the distance between both gas containers and the NOx adsorbent filling container can be increased, but in that case, it is necessary to secure a space for rotational movement, and the occupied volume of the apparatus increases dramatically. .

  Therefore, it is effective to promote convection by attaching an electric heater to the ascending pipe and heating at the start of replacement. Specifically, the connection pipes of the release valves 1 to 4, the insertion pipes 15 and 16 extending into the first gas container 9 and the second gas container 10, and the NOx adsorbent filling container 11 from below upward. An electric heater is attached to the insertion tube 18 or the like extending to the end.

 In the above procedure (3), the connection pipes of the on-off valve 2 and the on-off valve 3 and the corresponding insertion pipes are used for ascending, so these are heated. In the procedure (5), since the connecting pipes of the on-off valves 1 and 4 and the corresponding insertion pipes are used for ascending, these are heated.

  By this method, it is possible to shorten the time until the start of convection and increase the driving force of convection, and the time required for gas replacement is greatly reduced. Further, various means such as use of a forced drive fan can be employed for promoting the stay.

  The present invention can be used as an exhaust gas treatment device or an air purification device by being installed at a NOx pollutant gas emission source or a peripheral point thereof. In particular, it is effective for the treatment of low concentration NOx and is suitable for purification of NOx-contaminated air.

(A) is a cross-sectional view of a NOx adsorbent filling container and a gas displacement device, and (b) is a longitudinal front view thereof. BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram which shows the downward direction from the upper side of a paper surface by the perpendicular direction in Example 1 of this invention, (a) shows the 1st state by which the 1st gas container 9 is arrange | positioned upward, (b) is downward The 2nd state arrange | positioned is shown.

Explanation of symbols

9 First Gas Container 10 Second Gas Container 11 NOx Adsorbent Filling Container 12 Adsorbent 13 Cylindrical Cover 14 Rotating Movable Gas Seal
15 Connection pipe 16 Connection pipe 17 Curved pipe
18 curved pipes

Claims (8)

A first gas container filled with carbon dioxide gas is disposed above a NOx adsorbent filled container filled with NOx adsorbent, and a second gas container filled with nitrogen gas is disposed below, and the NOx adsorbent filled container; The first gas container and the second gas container are connected to each other so that the NOx adsorbent filling container can be turned upside down by two connecting pipes each provided with an on-off valve,
NOx is adsorbed on the NOx adsorbent by circulating NOx pollutant gas through the NOx adsorbent filling container,
At the end of the adsorption operation, the carbon dioxide gas in the upper first gas container is allowed to flow downward in the NOx adsorbent filling container to replace the adsorbed gas in the NOx adsorbent filling container,
The carbon dioxide gas in the NOx adsorbent filling container is caused to flow down into the second gas container below, and the nitrogen gas in the second gas container is replaced with nitrogen gas in the NOx adsorbent filling container,
Next, desorption of NOx adsorbed on the NOx adsorbent by depressurization or heating,
NOx is decomposed by circulating NOx desorbed in the NOx adsorbent filling container between the discharge container,
Then reverse the position of the upper and lower first gas container and the second gas container,
The carbon dioxide gas in the upper second gas container is allowed to flow downward in the NOx adsorbent filling container to replace the treated gas in the NOx adsorbent filling container,
The carbon dioxide gas in the NOx adsorbent filling container is caused to flow down to the first gas container below, and the adsorbed gas in the NOx adsorbent filling container is filled by replacing the adsorbed gas in the first gas container,
Again, NOx polluted gas is circulated and a series of operations to perform the adsorption operation are repeated until the oxygen concentration in the nitrogen gas increases and the efficiency of the discharge treatment decreases, and then the nitrogen gas is replaced. Gas replacement occlusion discharge NOx treatment method.   2. The gas replacement occlusion discharge NOx treatment method according to claim 1, wherein the volume inside the first gas container and the second gas container is set equal to the void volume in the NOx adsorbent-filled container. The filling gas in the gas container located below is N ₂ / NOx mixed gas,
An oxygen removal agent filling container is provided in the front stage of the discharge container,
NOx decomposition by discharge is performed only to the same extent as the amount of desorption from the NOx adsorbent,
NOx adsorption, gas replacement, NOx desorption, discharge treatment, gas replacement, NOx adsorption are repeated until the oxygen scavenger is deactivated.
2. The gas replacement occlusion discharge NOx treatment method according to claim 1, wherein the oxygen removing agent is replaced or regenerated thereafter. One of each of the two connecting pipes connecting the upper and lower gas containers and the NOx adsorbent filling container is inserted into the gas container,
Insert the pipe from the connection port on the side of the NOx adsorbent filling container facing the other connection pipe into the container,
An electric heater is attached to at least one of the inner intubation pipes in the upper and lower gas containers and their connection pipes, and the upper intubation pipe in the NOx adsorbent filling container, and the corresponding connection pipe on the gas container side,
2. The gas replacement occlusion discharge NOx treatment method according to claim 1 , wherein convection is promoted by heating a tube used as a rising tube during a gas replacement operation. The first gas container is arranged above the NOx adsorbent filling container filled with NOx adsorbent inside, and the second gas container is arranged below,
The NOx adsorbent filling container and the first gas container and the second gas container are connected to each other so that the NOx adsorbent filling container can be turned upside down by two connecting pipes each provided with an on-off valve.
Piping the NOx adsorbent so that NOx can be adsorbed by circulating NOx pollutant gas through the NOx adsorbent filling container,
The first gas container is filled with carbon dioxide gas,
The second gas container is filled with nitrogen gas,
The NOx adsorbent filling container and the discharge container are connected via an on-off valve,
Gas replacement type occlusion discharge NOx treatment characterized in that the gas in the first gas container and the NOx adsorbent filling container and the gas in the NOx adsorbent filling container and the second gas container can be sequentially replaced. apparatus.   6. The gas replacement occlusion discharge NOx treatment apparatus according to claim 5, wherein the volume inside the first gas container and the second gas container is set equal to the void volume in the NOx adsorbent filling container. The filling gas in the gas container located below is N ₂ / NOx mixed gas,
An oxygen removal agent filling container is provided in the front stage of the discharge container,
6. The gas replacement type occlusion discharge NOx processing apparatus according to claim 5, wherein a series of operations of NOx adsorption, gas replacement, NOx desorption, discharge treatment, gas replacement, and NOx adsorption are repeated until the oxygen removing agent is deactivated. From each of the two connecting pipes connecting the upper and lower gas containers and the NOx adsorbent filling container, one is inserted into the gas container and from the connection port on the NOx adsorbent filling container side facing the other connecting pipe. Insert the tube into the container,
An intubation tube in the upper and lower gas containers and their connection pipes, an inner intubation pipe in the upward direction in the NOx adsorbent filling container, and an electric heater for promoting convection in at least one of the corresponding connection pipes on the gas container side The gas replacement occlusion discharge NOx treatment apparatus according to claim 5, which is attached.

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