JP6586199B1 - Exhaust gas treatment system - Google Patents

Abstract

An object of the present invention is to provide an exhaust gas treatment system that can operate safely, at a low cost, and stably, while suppressing deterioration of the catalytic functions of an oxidation catalyst and a denitration catalyst when treating exhaust gas discharged from a combustion facility. An exhaust gas treatment system for treating exhaust gas discharged from a combustion facility includes a pre-processing unit that reduces or removes an organosilicon compound contained in the exhaust gas, and oxidizes carbon monoxide contained in the exhaust gas. And the main treatment unit 12 having a denitration catalyst 12b for reducing nitrogen oxides contained in the exhaust gas, and the pretreatment unit 11 is replaced with a used oxidation catalyst 12a and / or a denitration catalyst. 12b. [Selection] Figure 1

Description

  The present invention relates to an exhaust gas treatment system for treating exhaust gas discharged from a combustion facility.

  In plant cultivation facilities such as greenhouses and plant factories, carbon dioxide-containing gas with adjusted carbon dioxide concentration is used as plant growth gas in order to adjust the growth state of cultivated plants according to consumption demand and shipping time. . Until now, liquefied carbon dioxide and fossil fuel combustion gas have been mainly used as a source of carbon dioxide-containing gas. From the viewpoint of environmental protection and cost reduction, biomass power generation facilities, garbage incineration facilities, etc. The use of combustion gas (exhaust gas) discharged from combustion facilities is being studied.

  However, the exhaust gas discharged from the combustion equipment may contain various impurities in addition to carbon dioxide. For example, in biomass power generation facilities, plant-derived wastes (biomass, etc.) such as wood chips and large sawdust are burned, but since plants contain nitrogen, nitrogen is produced when biomass is burned. . Further, when the combustion of biomass is incomplete, carbon monoxide is generated. Nitrogen oxides and carbon monoxide are harmful to the human body. If these harmful gases are contained in plant growth gas, they may adversely affect the safety and health of farmers working in plant cultivation facilities. There is. Nitrogen oxides may inhibit plant growth. Therefore, it is desirable that the exhaust gas supplied to the plant cultivation facility as a plant growth gas removes nitrogen oxides and carbon monoxide as much as possible to improve safety. Therefore, in order to reduce nitrogen oxides and carbon monoxide in the exhaust gas discharged from the combustion facility, in a conventional exhaust gas treatment system, a denitration catalyst that reduces nitrogen oxides to nitrogen, and carbon monoxide to carbon dioxide. An oxidation catalyst that oxidizes was installed (see, for example, Patent Document 1). In the exhaust gas supply system described in Patent Document 1, when exhaust gas generated by burning biomass or the like is supplied to a garden house, a denitration catalyst and an oxidation catalyst are provided in the middle of the exhaust gas flow path connected to the garden house. Nitrogen oxides and carbon monoxide in it are reduced.

JP 2017-93393 A

  By the way, because plant-derived waste such as biomass contains trace amounts of silicon, combustion of biomass fuel made from biomass produces gaseous organosilicon compounds, which are used for denitration catalysts and oxidation. It may adhere to the surface of the catalyst and cover the surface of the catalyst, and the catalyst function may be lost (poisoned). Also in the exhaust gas supply system of Patent Document 1, when biomass fuel is used, the catalytic function of the denitration catalyst and the oxidation catalyst is reduced due to poisoning accompanying the adhesion of the organosilicon compound to the catalyst surface, and in the exhaust gas supplied to the plant cultivation equipment Nitrogen oxides and carbon monoxide may not be sufficiently reduced. Thus, in the conventional exhaust gas treatment system represented by Patent Document 1, the plant growth gas is safely and inexpensively and stably supplied to the plant cultivation facility while reducing nitrogen oxides and carbon monoxide in the exhaust gas. There was room for improvement in terms of supplying

  The present invention has been made in view of the above problems, and in processing exhaust gas discharged from a combustion facility, it is safe and low-cost while suppressing deterioration of the catalytic function of an oxidation catalyst and a denitration catalyst. An object is to provide an exhaust gas treatment system capable of stable operation.

The characteristic configuration of the exhaust gas treatment system according to the present invention for solving the above problems is as follows:
An exhaust gas treatment system for treating exhaust gas discharged from a combustion facility,
A pretreatment section for reducing or removing the organosilicon compound contained in the exhaust gas;
A main treatment unit having an oxidation catalyst for oxidizing carbon monoxide contained in the exhaust gas and / or a denitration catalyst for reducing nitrogen oxide contained in the exhaust gas;
The pretreatment part is to have a used oxidation catalyst and / or denitration catalyst.

  According to the exhaust gas treatment system of this configuration, carbon monoxide and / or nitrogen oxides contained in the exhaust gas are reduced or removed by the present treatment unit in a state where the organosilicon compound contained in the exhaust gas is reduced or removed in advance by the pretreatment unit. Can be removed. Therefore, the organosilicon compound does not substantially adhere to the surface of the oxidation catalyst and / or the denitration catalyst in the present processing section, and the catalytic function of the oxidation catalyst and / or the denitration catalyst can be maintained for a long time. In addition, by using a used oxidation catalyst and / or denitration catalyst as a catalyst in the pretreatment section for reducing or removing organosilicon compounds, the oxidation catalyst and / or denitration catalyst that cannot be used in this treatment section can be used effectively. can do. Even if it is an oxidation catalyst and / or a denitration catalyst that cannot be used as this processing section, the catalytic function remains to some extent, so by using such a used catalyst, it is safe and low-cost. The necessary and sufficient effect can be achieved as the pre-processing unit.

In the exhaust gas treatment system according to the present invention,
The main processing unit is configured as a catalyst unit in which a plurality of catalyst elements forming the oxidation catalyst and / or the denitration catalyst are arranged in series in the flow direction of the exhaust gas,
When the catalytic function of the catalyst element on the most upstream side of the catalyst unit is lowered, the catalyst element on the most upstream side is separated from the catalyst unit and moved to the pretreatment unit, and the catalyst element on the most downstream side is moved. It is preferable that an unused catalyst element is connected immediately after that to function as a catalyst unit of a new main processing unit.

  According to the exhaust gas treatment system of this configuration, since this treatment unit is configured as a catalyst unit in which a plurality of catalyst elements are arranged in series, only the catalyst element having a reduced catalyst function is replaced among the plurality of catalyst elements. Thus, the catalyst function of the entire catalyst unit can be maintained above a certain level. For example, in the case where the catalytic function of the most upstream side catalyst element is less than a specified value among the catalyst units of this processing unit, the most upstream side catalyst element is separated from the catalyst unit and moved to the preprocessing unit, By connecting an unused catalyst element immediately after the most downstream catalyst element, a continuous replacement cycle of the catalyst elements constituting the catalyst unit of this processing unit is established. Thereby, the fluctuation | variation of the catalyst function of the catalyst unit of this process part decreases, and the exhaust gas treatment system which can be stably operated continuously can be implement | achieved.

In the exhaust gas treatment system according to the present invention,
The pretreatment unit is configured as a catalyst unit in which a plurality of catalyst elements forming the used oxidation catalyst and / or the used denitration catalyst are arranged in series in the exhaust gas flow direction,
A catalyst element having a reduced catalytic function separated from the catalyst unit of the main processing unit is connected immediately after the catalyst element on the most downstream side of the catalyst unit of the preprocessing unit, and on the most upstream side of the preprocessing unit. It is preferable that the catalyst element is separated from the catalyst unit of the pretreatment unit and functions as a catalyst unit of a new pretreatment unit.

  According to the exhaust gas treatment system of this configuration, since the pretreatment unit is configured as a catalyst unit in which a plurality of catalyst elements are arranged in series, only the catalyst element that does not perform the catalytic function is replaced among the plurality of catalyst elements. As a result, the catalyst function of the entire catalyst unit can be maintained above a certain level. For example, if the catalytic function of the most upstream catalyst element of the catalyst unit in the pretreatment unit is almost lost, the most upstream catalyst element is disconnected from the catalyst unit and immediately after the most downstream catalyst element. A continuous replacement cycle of the catalyst elements constituting the catalyst unit of the pretreatment unit is established by connecting the catalyst element having a reduced function as the main treatment unit separated from the catalyst unit of the treatment unit. Thereby, the fluctuation | variation of the catalyst function of the catalyst unit of a pre-processing part decreases, and the exhaust gas treatment system which can be stably operated continuously can be implement | achieved.

In the exhaust gas treatment system according to the present invention,
It is preferable that a reheating unit for heating the exhaust gas discharged from the combustion facility is provided in a stage preceding the pretreatment unit.

  According to the exhaust gas treatment system of this configuration, the temperature of the exhaust gas discharged from the combustion facility gradually decreases, but by heating in the reheating unit, the exhaust gas remains in the high temperature state while maintaining the high temperature state. It can flow in and the catalytic reaction between the exhaust gas and each catalyst can proceed.

In the exhaust gas treatment system according to the present invention,
In the reheating unit, it is preferable that the heating temperature of the exhaust gas is set to 160 ° C. or higher.

  According to the exhaust gas treatment system of the present configuration, if the heating temperature of the exhaust gas in the reheating unit is set to 160 ° C. or higher, the catalytic reaction between the exhaust gas and each catalyst becomes active, and carbon monoxide and / or Alternatively, nitrogen oxides and organosilicon compounds can be sufficiently reduced or removed.

The characteristic configuration of the exhaust gas treatment system according to the present invention for solving the above problems is as follows:
An exhaust gas treatment system for treating exhaust gas discharged from a combustion facility,
A first treatment unit having an oxidation catalyst and / or a denitration catalyst with reduced function;
A second treatment part having an oxidation catalyst and / or a denitration catalyst whose function is not lowered;
A switching channel capable of switching a flow direction of the exhaust gas between the first processing unit and the second processing unit;
When the catalyst function of the second processing unit is a specified value or more, the switching flow path is switched so that the exhaust gas flows from the first processing unit to the second processing unit,
When the catalyst function of the second processing unit becomes less than a specified value, the oxidation catalyst and / or the denitration catalyst whose function of the first processing unit is reduced are changed to the oxidation catalyst and / or the denitration catalyst whose function is not reduced. The switching flow path is switched so that the exhaust gas flows from the second processing section to the first processing section.

  According to the exhaust gas treatment system of the present configuration, the first treatment unit and the second treatment unit are provided with a switching channel that can switch the flow direction of the exhaust gas between the first treatment unit and the second treatment unit. When the catalytic function of one oxidation catalyst and / or denitration catalyst is greatly reduced, the oxidation catalyst and / or denitration catalyst is replaced with a new oxidation catalyst and / or denitration catalyst whose catalytic function has not decreased, and then The exhaust gas treatment can be resumed only by switching the flow direction of the exhaust gas by the switching channel. Thus, according to the exhaust gas treatment system of this configuration, the period during which the operation of the exhaust gas treatment system is interrupted can be shortened, and efficient exhaust gas treatment becomes possible.

In the exhaust gas treatment system according to the present invention,
It is preferable to provide a supply unit that supplies the treated exhaust gas to the plant cultivation facility.

  According to the exhaust gas treatment system of this configuration, it can be suitably used as an application for supplying plant growth gas to a plant cultivation facility.

FIG. 1 is a block diagram showing the overall configuration of the exhaust gas treatment system according to the first embodiment. FIG. 2 is a schematic diagram of the preprocessing unit and the main processing unit. FIG. 3 is an explanatory diagram showing a replacement procedure of each catalyst in the pretreatment unit and the main treatment unit. FIG. 4 is a block diagram showing the overall configuration of the exhaust gas treatment system according to the second embodiment. FIG. 5 is an explanatory diagram illustrating a switching procedure of the switching flow path between the first processing unit and the second processing unit.

  Hereinafter, an embodiment relating to an exhaust gas treatment system according to the present invention will be described. However, the present invention is not intended to be limited to the configuration described below.

<First embodiment>
〔overall structure〕
FIG. 1 is a block diagram showing an overall configuration of an exhaust gas treatment system 100 according to the first embodiment. The exhaust gas treatment system 100 supplies combustion gas containing carbon dioxide (hereinafter referred to as “exhaust gas”) discharged from the combustion facility 50 that burns biomass, general garbage, and the like to the plant cultivation facility 60 as a plant growth gas. System. The exhaust gas generated in the combustion facility 50 is attracted by the blower 51 and forcibly exhausted from the exhaust pipe 52 to the outside. A branch pipe 53 is provided in the middle of the exhaust pipe 52, and a part of the exhaust gas to be supplied to the plant cultivation facility 60 is passed through the bag filter 54. In the bag filter 54, dust, tar, acid gas, etc. contained in the exhaust gas are reduced or removed. The exhaust gas from which dust, tar, acid gas, etc. has been reduced or removed contains carbon dioxide, nitrogen and oxygen as the main components. In addition, nitrogen oxides, carbon monoxide, organosilicon compounds, etc. Impurities are also included. Nitrogen oxide and carbon monoxide are gases harmful to the human body, so it is desirable to reduce them as much as possible for safety. In addition, the organosilicon compound may adhere to the surface of the catalyst to form an organosilicon polymer or silicon oxide, thereby losing the function of the catalyst. Therefore, in order to reduce or remove these impurities, the exhaust gas after passing through the bag filter 54 is introduced into the exhaust gas treatment system 100 for further purification. Hereinafter, a detailed configuration of the exhaust gas treatment system 100 will be described.

  In FIG. 1, a portion surrounded by a broken line corresponds to the exhaust gas treatment system 100. The exhaust gas treatment system 100 includes a pretreatment unit 11 and a main treatment unit 12, and further includes a reheating unit 13 at a stage upstream (upstream side) of the pretreatment unit 11.

  The pretreatment unit 11 is disposed in front of the main treatment unit 12 and has a function of reducing or removing an organosilicon compound contained in the exhaust gas. Thereby, it is prevented that the organosilicon compound substantially flows into the processing unit 12. The pretreatment unit 11 contains a catalyst for reducing or removing the organosilicon compound. The present processing unit 12 contains an oxidation catalyst that oxidizes carbon monoxide and / or a denitration catalyst that reduces nitrogen oxide, thereby oxidizing the carbon monoxide contained in the exhaust gas, and oxidizing the nitrogen contained in the exhaust gas. It has the function of reducing things or both. In addition, ammonia is used together as a reducing agent in the reduction of nitrogen oxides by the denitration catalyst. Since the exhaust gas passes through the pretreatment unit 11 and the main processing unit 12, the exhaust gas supplied to the plant cultivation facility 60 described later contains almost no organosilicon compound and carbon monoxide and / or nitrogen oxides. Therefore, it is safe for farmers and is suitable as a plant growth gas without inhibiting the growth of plants.

  The reheating unit 13 has a function of heating the exhaust gas discharged from the combustion facility 50. Although the temperature of the exhaust gas discharged from the combustion facility 50 gradually decreases, the exhaust gas flows into the pre-processing unit 11 and the main processing unit 12 while being maintained at a high temperature by being heated by the reheating unit 13. Catalytic reaction with each catalyst can be promoted. The heating temperature of the exhaust gas by the reheating unit 13 is preferably 160 ° C. or higher, and more preferably 190 ° C. or higher. If the heating temperature of the exhaust gas is 160 ° C. or higher, the catalytic reaction between the exhaust gas and each catalyst becomes active, and about carbon monoxide and / or nitrogen oxide (initial concentration: about 6 to 1000 ppm) contained in the exhaust gas. Ultimately, the organosilicon compound (initial concentration: about 2 to 10 ppb) contained in the exhaust gas can be reduced to 5 ppm or less, and finally to 1 ppb or less. In addition, the higher the exhaust gas heating temperature, the less the deterioration of the catalyst. When the temperature of the exhaust gas discharged from the combustion facility 50 is 160 ° C. or higher, it may be introduced as it is into the pretreatment unit 11 and the main treatment unit 12 without being reheated. That is, the reheating unit 13 may be provided as necessary when the temperature of the exhaust gas is low.

[Preprocessing section and main processing section]
FIG. 2 is a schematic diagram of the preprocessing unit 11 and the main processing unit 12, and shows three configuration examples. In FIG. 2A, the main catalyst 12 contains the oxidation catalyst 12a and the denitration catalyst 12b, and the pretreatment unit 11 contains the oxidation catalyst 11a. The oxidation catalyst 11a of the pretreatment unit 11 is the oxidation catalyst 12a used in the main treatment unit 12 and is removed for replacement. That is, the oxidation catalyst 11a is a catalyst similar to the oxidation catalyst 12a, but has a reduced catalyst function. In the present processing unit 12, ammonia is added to the exhaust gas as a reducing agent immediately before the exhaust gas is introduced into the denitration catalyst 12b. The method of adding ammonia to the exhaust gas may be carried out manually by means such as a syringe with an addition hole provided in the exhaust gas flow path, or may be provided with addition means (not shown) such as a spray device. In FIG. 2B, the main treatment unit 12 contains the oxidation catalyst 12 a and the denitration catalyst 12 b, and the pretreatment unit 11 contains the denitration catalyst 11 b. The denitration catalyst 11b of the pretreatment unit 11 is the denitration catalyst 12b used in the main treatment unit 12, and is removed for replacement. That is, the denitration catalyst 11b is a catalyst similar to the denitration catalyst 12b, but has a reduced catalyst function. In addition, in this process part 12, it is the same as that of Fig.2 (a) that ammonia is added in the position just before the denitration catalyst 12b. In FIG. 2 (c), the main treatment unit 12 contains the oxidation catalyst 12 a and the denitration catalyst 12 b, and the pretreatment unit 11 contains the oxidation catalyst 11 a and the denitration catalyst 11 b. The oxidation catalyst 11a and the denitration catalyst 11b are used in the same manner as described above, and have a reduced catalyst function. In addition, in this process part 12, it is the same as that of Fig.2 (a) and (b) that ammonia is added in the position just before the denitration catalyst 12b. As described above, the pretreatment unit 11 accommodates the used oxidation catalyst 11 a and / or the denitration catalyst 11 b after being used in the main treatment unit 12. Even if these used catalysts cannot be used as the main treatment unit 12 due to a decrease or loss of oxidation promotion action and / or reduction promotion action, other catalyst functions (for example, adsorption action) remain to some extent. Therefore, there is no practical problem in the use for reducing or removing the organosilicon compound in the exhaust gas. As a used catalyst, as long as it has 1 to 99% of a catalyst function (oxidation promoting action, reduction promoting action, or adsorption action) as compared with an unused catalyst, it is sufficiently used as the pretreatment section 11. Is possible. By using such a used oxidation catalyst 11a and / or denitration catalyst 11b as the catalyst of the pretreatment unit 11, it becomes possible to reduce or remove the organosilicon compound in the exhaust gas at low cost. Further, since the replaced used oxidation catalyst 11a and / or denitration catalyst 11b is reused, it is also effective in terms of protecting resources such as precious metals and rare metals used in the catalyst.

  In the configuration example shown in FIG. 2, the used oxidation catalyst 11a and / or the denitration catalyst 11b having a reduced catalyst function are used as the catalyst of the pretreatment unit 11, but the catalyst function is sufficient although it has been used. It is also possible to use the remaining oxidation catalyst 12a and / or the denitration catalyst 12b. In this case, since the catalytic function of the pretreatment unit 11 can be maintained for a long period of time, even if the catalytic function of the pretreatment unit 11 is slightly lowered from the initial state, it is not necessary to immediately replace the catalyst, and it can be used as it is. can do.

[Catalyst replacement procedure]
In order to enable continuous operation of the exhaust gas treatment system 100, it is required to keep the impurity concentration in the exhaust gas below a certain level by suppressing fluctuations in the catalyst function of the pretreatment unit 11 and the main treatment unit 12 as a whole. . Therefore, in the exhaust gas treatment system 100 of the first embodiment, the pretreatment unit 11 and the main treatment unit 12 are each configured as a catalyst unit in which a plurality of catalyst elements are arranged in series, and the catalyst is replaced in units of catalyst elements. Is preferred. In addition, it is preferable to comprise a catalyst element with the porous material with a large specific surface area, in order to improve the contact property with waste gas. The catalyst element is preferably formed as a bulk body having a certain size and shape in consideration of ease of replacement after use. Hereinafter, the replacement procedure of the catalyst element in the pretreatment unit 11 and the main treatment unit 12 will be described.

  FIG. 3 is an explanatory diagram showing a replacement procedure of the respective catalysts (the oxidation catalysts 11a and 12a and the denitration catalysts 11b and 12b) in the pre-processing unit 11 and the main processing unit 12. In FIG. 3, the thickness of the line for drawing each catalyst represents the degree of the catalyst function of each catalyst, which means that the catalyst function decreases as the line becomes thinner. In addition, although illustration is abbreviate | omitted, in this process part 12, it is the same as that of FIG. 2 that ammonia is added to exhaust gas in the position just before exhaust gas is introduce | transduced into the denitration catalyst 12b. As shown in FIG. 3 (a), the pretreatment unit 11 is a catalyst unit in which a plurality of catalyst elements, which are used oxidation catalysts 11a and used denitration catalysts 11b, are alternately arranged in series in the exhaust gas flow direction. The present processing unit 12 is configured as a catalyst unit in which a plurality of catalyst elements that are the oxidation catalyst 12a and the denitration catalyst 12b are alternately arranged in series in the exhaust gas flow direction. Note that the alternating arrangement of the catalyst elements in the main processing unit 12 shown in FIG. 3A is merely an example. For example, in the present processing section 12, a configuration in which a plurality of oxidation catalysts 12a are arranged adjacent to each other, and a plurality of denitration catalysts 12b are arranged next to each other, or a plurality of denitration catalysts 12b are arranged to be adjacent to each other, A configuration may be adopted in which a plurality of oxidation catalysts 12a are arranged adjacent to each other. Also in these configurations, ammonia is added to the denitration catalyst 12b immediately before the exhaust gas is introduced. When a plurality of denitration catalysts 12b are arranged adjacent to each other, ammonia may be added at a position immediately before the most upstream denitration catalyst 12b. The exhaust gas to be treated passes through the pretreatment unit 11 and the main treatment unit 12 in order from the left side to the right side of the drawing. When the exhaust gas flow rate (integrated amount) reaches a certain level or more, the catalytic function of the oxidation catalyst 11a, which is the most upstream side catalyst element, in the pretreatment unit 11 decreases, and in the main processing unit 12, the most upstream side catalyst. The catalytic function of the oxidation catalyst 12a as the element is lowered. Here, for the oxidation catalyst 12a in the present processing unit 12, for example, when the catalyst function of the unused oxidation catalyst 12a is assumed to be 100%, an appropriate numerical value (for example, 95%) of 90 to 99% is reached. It is presumed that the catalyst function was lowered. When the catalytic function is lowered, as shown in FIG. 3B, the most upstream side oxidation catalyst 11a in the pretreatment unit 11 loses almost the catalytic function and becomes the oxidation catalyst 11a ', and the most upstream side in the main processing unit 12 The oxidation catalyst 12a is reduced in catalytic function to become an oxidation catalyst 12a ′. Therefore, as shown in FIG. 3 (c), the oxidation catalyst 11a ′ having almost lost the catalytic function is separated from the catalyst unit in the pretreatment unit 11, and the oxidation catalyst 12a ′ having a reduced catalytic function is removed in the main processing unit 12. Disconnect from the catalyst unit. The oxidation catalyst 11a ′ cut off in the pretreatment unit 11 is regenerated in a separate process or discarded as it is. As shown in FIG. 3D, the oxidation catalyst 12a ′ separated in the main processing unit 12 is connected immediately after the denitration catalyst 11b which is the most downstream side catalyst element of the preprocessing unit 11, and as a result, FIG. As shown in FIG. 3 (e), a new catalyst unit including a denitration catalyst 11b, an oxidation catalyst 11a, a denitration catalyst 11b, and an oxidation catalyst 11a (oxidation catalyst 12a ′) is configured. In the main processing unit 12, as shown in FIG. 3D, an unused oxidation catalyst 12a is connected immediately after the denitration catalyst 12b, which is the most downstream side catalyst element of the main processing unit 12, and as a result, FIG. As shown in FIG. 3 (e), a new catalyst unit including a denitration catalyst 12b, an oxidation catalyst 12a, a denitration catalyst 12b, and an oxidation catalyst 12a is configured. And the exchange procedure similar to Fig.3 (a)-FIG.3 (e) is repeated over the period when the waste gas processing system 100 is operated. Thus, according to the exhaust gas treatment system 100 of the first embodiment, the pretreatment unit 11 and the main treatment unit 12 as a whole can be obtained by replacing only the catalyst element having a reduced catalyst function among the plurality of catalyst elements. Variations in the catalyst function are suppressed, and as a result, the impurity concentration in the exhaust gas can be maintained below a certain level. Further, the exhaust gas treatment system 100 can be continuously operated by establishing a continuous replacement cycle of the catalyst elements 11a, 11b, 12a, and 12b constituting the catalyst unit.

[Supply of plant growth gas]
The exhaust gas that has been treated by the pretreatment unit 11 and the main treatment unit 12 and reduced the organosilicon compound, carbon monoxide and / or nitrogen oxides to a significant concentration is attracted by the blower 61 as shown in FIG. Then, after being cooled to an appropriate temperature by the cooling device 62, it is supplied from the supply pipe 63, which is a supply unit, to the plant cultivation facility 60 as plant growth gas. Examples of the plant cultivation facility 60 include a vinyl house, a glass house, and a plant factory. Thus, the exhaust gas treatment system 100 of the first embodiment can be suitably used as an application for supplying plant growth gas to the plant cultivation facility 60.

<Second embodiment>
〔overall structure〕
FIG. 4 is a block diagram showing the overall configuration of the exhaust gas treatment system 200 according to the second embodiment. The exhaust gas treatment system 200 according to the second embodiment is provided with a switching channel capable of switching the flow direction of the exhaust gas between the pretreatment unit 11 and the main treatment unit 12 in the exhaust gas treatment system 100 according to the first embodiment. Is. In addition, when the flow direction of exhaust gas is switched, since the exhaust gas passes through the main processing unit 12 and the preprocessing unit 11 in this order, the function of the preprocessing unit 11 and the function of the main processing unit 12 are switched. Therefore, in the second embodiment, the preprocessing unit 11 is referred to as a first processing unit 15 and the main processing unit 12 is referred to as a second processing unit 25, and the type of processing is not specified. Further, in the exhaust gas treatment system 200 of the second embodiment, the configurations other than the first processing unit 15, the second processing unit 25, and the switching channel 30 are the same as those described in the exhaust gas treatment system 100 of the first embodiment. Since it is substantially the same, detailed description is abbreviate | omitted.

[Switching flow path]
The switching channel 30 includes a main channel 31 that connects the first processing unit 15 and the second processing unit 25, a first bypass channel 32 that bypasses the first processing unit 15 and the second processing unit 25, and A second bypass channel 33. FIG. 5 is an explanatory diagram showing a switching procedure of the switching channel 30 between the first processing unit 15 and the second processing unit 25. FIG. 5 illustrates a configuration in which the oxidation catalyst 25 a and the denitration catalyst 25 b are accommodated in the second processing unit 25, and the used oxidation catalyst 15 a and the denitration catalyst 15 b whose functions are reduced are accommodated in the first treatment unit 15. In FIG. 5, the flow path indicated by a thick line means that exhaust gas is flowing, and the arrows shown along the flow path indicate the flow direction of the exhaust gas. In the switching channel 30, a first valve 34 and a second valve 35 are provided in the main channel 31 with the first processing unit 15 and the second processing unit 25 interposed therebetween, and a third valve 36 is provided in the first bypass channel 32. And a fourth valve 37 is provided in the second bypass flow path 33. Switching of the flow direction of the exhaust gas between the first processing unit 15 and the second processing unit 25 is performed by opening and closing each valve described above. Hereinafter, the valve operation of the switching channel 30 will be described.

[Valve operation of switching channel]
At the start of operation of the exhaust gas treatment system 200, as shown in FIG. 5A, the first valve 34 and the second valve 35 are opened, and the third valve 36 and the fourth valve 37 are closed. When exhaust gas is allowed to flow in this state, the exhaust gas proceeds through the main flow path 31 in the order of the first processing unit 15 and the second processing unit 25. In this case, the organosilicon compound is reduced in the first processing unit 15, and carbon monoxide and nitrogen oxides are reduced in the second processing unit 25. Then, if the exhaust gas flow is continued as it is, the functions of the respective catalysts accommodated in the first processing unit 15 and the second processing unit 25 gradually decrease as shown in FIG. During the period when the catalyst function of the processing unit 25 is equal to or greater than the specified value, the exhaust gas flow is continued. As the specified value, for example, when the catalyst function of an unused catalyst is 100%, an appropriate numerical value of 90 to 99% (for example, 95%) can be adopted. When the catalyst function of the second processing unit 25 becomes less than the specified value, as shown in FIG. 5C, the first valve 34 and the second valve 35 are closed to temporarily stop the flow of exhaust gas. Then, as shown in FIG. 5 (d), the used oxidation catalyst 15a and denitration catalyst 15b are taken out from the first processing unit 15, and replaced with the first processing unit 15 as shown in FIG. 5 (e). A new oxidation catalyst 15a and denitration catalyst 15b whose functions are not lowered are accommodated. Then, as shown in FIG. 5F, the third valve 36 and the fourth valve 37 are opened while the first valve 34 and the second valve 35 are closed. When the flow of the exhaust gas is resumed in this state, the exhaust gas proceeds in the order of the second processing unit 25 and the first processing unit 15 through the first bypass flow path 32, and then downstream through the second bypass circuit 33. To the plant cultivation facility 60. In this case, the organosilicon compound is reduced in the second processing unit 25, and carbon monoxide and nitrogen oxides are reduced in the first processing unit 15. In the exhaust gas treatment system 200 of the second embodiment, ammonia is added to the exhaust gas as a reducing agent immediately before the exhaust gas is introduced into the denitration catalyst 15b. It is the same. Thus, according to the exhaust gas treatment system 200 of the second embodiment, when one of the catalyst functions of the first processing unit 15 and the second processing unit 25 is greatly reduced, the catalyst having the reduced catalyst function is catalyzed. Exhaust gas treatment can be resumed simply by replacing the catalyst with a new one whose function has not deteriorated and then switching the flow direction of the exhaust gas through the switching channel. As a result, the period during which the operation of the exhaust gas treatment system 200 is interrupted can be shortened, and efficient exhaust gas treatment becomes possible.

<Another embodiment>
The exhaust gas treatment system of the present invention has the configuration described in the above embodiment as long as the effects of the present invention of reducing impurities in the exhaust gas can be achieved safely and at low cost while suppressing a decrease in catalyst function. It is also possible to change. Some such modifications will be described as another embodiment.

[Another embodiment 1]
The exhaust gas treatment system described in the above embodiment is configured to connect one main processing unit to one preprocessing unit, but has a configuration in which a plurality of main processing units are connected to one preprocessing unit. It is also possible to do. If multiple main treatment units are connected to a single pretreatment unit, exhaust gas treatment using multiple catalysts can be performed. By appropriately selecting the type of catalyst, other than carbon monoxide and nitrogen oxides It is also possible to treat other harmful gases (for example, sulfur oxides, hydrogen halides, organophosphorus compounds, ethylene gas, etc.).

[Another embodiment 2]
In the exhaust gas treatment system described in the above embodiment, the form of the catalyst is configured as a bulk body having a certain shape, but it is also possible to adopt a form such as a granular body or a powder. In this case, since a large contact area between the exhaust gas and the catalyst can be secured, the reactivity of the exhaust gas is increased, and the exhaust gas treatment can be performed even with a relatively small amount of catalyst. And the exchange amount of the catalyst after use can also be reduced. Moreover, it is also possible to make it the structure which enclosed the catalyst, such as a granular material and powder, in the container which has air permeability. In this case, although the reactivity between the exhaust gas and the catalyst is high, replacement and handling are easy.

[Another embodiment 3]
The exhaust gas treatment system described in the above embodiment is configured as a continuous exhaust gas treatment system that continuously treats exhaust gas discharged from the combustion facility through the pretreatment unit and the main treatment unit in order, but is a batch type. Alternatively, it may be configured as a semi-batch type exhaust gas treatment system. For example, exhaust gas discharged from a combustion facility is first introduced into a pretreatment container, and the organosilicon compound is removed by mixing and stirring the catalyst and the exhaust gas inside the pretreatment container, and then the exhaust gas is removed from the pretreatment container. It can also be set as the structure which removes carbon monoxide and / or a nitrogen oxide by moving to this processing container and mixing and stirring a catalyst and waste gas inside the said processing container. In this case, since the residence time of the exhaust gas in each processing container becomes longer, the contact time between the exhaust gas and each catalyst also becomes longer, and as a result, impurities in the exhaust gas can be reliably removed. In addition, since the pretreatment container and the present treatment container function as an exhaust gas buffer, even if the amount of exhaust gas generated from the combustion facility is temporarily increased or decreased, the exhaust gas treatment can be reliably handled.

  The exhaust gas treatment system of the present invention can be used for the purpose of supplying plant growth gas to plant cultivation facilities, but also for the purpose of supplying carbon dioxide-containing gas to facilities such as chemical factories, food factories, and electronic component factories. Is possible.

DESCRIPTION OF SYMBOLS 11 Pretreatment part 11a Used oxidation catalyst 11b Used denitration catalyst 12 Main treatment part 12a Oxidation catalyst 12b Denitration catalyst 13 Reheating part 15 First treatment part 25 Second treatment part 31 Main flow path (switching flow path)
32 First bypass channel (switching channel)
33 Second bypass channel (switching channel)
50 Combustion equipment 60 Plant cultivation facility 100 Exhaust gas treatment system (first embodiment)
200 Exhaust gas treatment system (second embodiment)

Claims (5)

An exhaust gas treatment system for treating exhaust gas discharged from a combustion facility,
A pretreatment section for reducing or removing the organosilicon compound contained in the exhaust gas;
A present processing section having a denitration catalyst for reducing nitrogen oxides contained in the oxidation catalyst及beauty before Symbol exhaust gases to oxidize carbon monoxide contained in the exhaust gas,
The preprocessing unit may have a spent oxidation catalyst and / or NO x removal catalyst,
The main processing unit is configured as a catalyst unit in which a plurality of catalyst elements forming the oxidation catalyst and catalyst elements forming the denitration catalyst are alternately arranged in series in the exhaust gas flow direction,
When the catalytic function of the catalyst element on the most upstream side of the catalyst unit is lowered, the catalyst element on the most upstream side is separated from the catalyst unit and moved to the pretreatment unit, and the catalyst element on the most downstream side is moved. An exhaust gas treatment system configured to connect an unused catalyst element immediately after that to function as a catalyst unit of a new main treatment unit . The pre-processing unit constructed as a catalyst unit in which the catalyst elements are arranged more series in the flow direction of the exhaust gas alternately to form the catalyst element及beauty before Symbol spent denitration catalyst to form the spent oxidation catalyst And
A catalyst element having a reduced catalytic function separated from the catalyst unit of the main processing unit is connected immediately after the catalyst element on the most downstream side of the catalyst unit of the preprocessing unit, and on the most upstream side of the preprocessing unit. The exhaust gas treatment system according to claim 1 , wherein the catalyst element is separated from the catalyst unit of the pretreatment unit and functions as a catalyst unit of a new pretreatment unit. The exhaust gas treatment system according to any one of claims 1 and 2 , wherein a reheating unit that heats the exhaust gas discharged from the combustion facility is provided in a stage preceding the pretreatment unit. The exhaust gas treatment system according to claim 3 , wherein the reheating unit has a heating temperature of the exhaust gas set to 160 ° C. or higher. The exhaust gas treatment system according to any one of claims 1 to 4 , further comprising a supply unit that supplies the treated exhaust gas to a plant cultivation facility.

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