WO2017002168A1

WO2017002168A1 - Exhaust gas treatment system and exhaust gas treatment method

Info

Publication number: WO2017002168A1
Application number: PCT/JP2015/068685
Authority: WO
Inventors: 知昭磯部; 増田　具承; 正志清澤; 耕次東野
Original assignee: 三菱日立パワーシステムズ株式会社
Priority date: 2015-06-29
Filing date: 2015-06-29
Publication date: 2017-01-05

Abstract

This exhaust gas treatment system (1) is provided with an oxidation reactor (10), a heat exchanger (15), a heater (20), a thermometer (29) and a heating amount controller (21). The oxidation reactor (10) is internally filled with a catalyst (11) wherein Pt is supported by a titania carrier, and oxidizes carbon monoxide contained in an exhaust gas (EX). The heat exchanger (15) heats the gas before oxidation (EXb), which is the gas before being treated by the oxidation reactor (10), by performing heat exchange between the gas before oxidation (EXb) and the oxidized gas (EXa), which is the gas after being treated by the oxidation reactor (10). The heater (20) heats the gas before oxidation (EXb) after passing through the heat exchanger (15). The heating amount controller (21) controls the amount of heating by the heater (20) so that the temperature detected by the thermometer (29) is within a predetermined temperature range.

Description

Exhaust gas treatment facility and exhaust gas treatment method

The present invention relates to an exhaust gas processing facility for oxidizing carbon monoxide in exhaust gas and an exhaust gas processing method.

When oxidizing carbon monoxide (hereinafter referred to as CO) in exhaust gas, generally, exhaust gas within a predetermined temperature range is brought into contact with a catalyst, and CO in the exhaust gas is catalytically combusted. Many.

As this catalyst, for example, as described in Patent Document 1 below, a catalyst in which Pt is supported on a titania carrier is known.

Japanese Patent No. 4508693

In the oxidation treatment of carbon monoxide, it is desired that when the exhaust gas starts to flow into the treatment apparatus, the carbon monoxide is immediately oxidized by this treatment apparatus, and thereafter the carbon monoxide is stably oxidized. Furthermore, it is desired to reduce running costs in the oxidation treatment of carbon monoxide.

Therefore, the present invention suppresses the running cost, suppresses the time lag from the start of the exhaust gas inflow to the start of the oxidation treatment of carbon monoxide at the time of cold start such as at the time of starting the plant, and then stably stabilizes the monoxide. It aims at providing the technique which can oxidize carbon.

An exhaust gas treatment facility as one aspect for achieving the above object is:
The Pt-Sb catalyst in which Pt and Sb are supported on the titania support, or the Pt catalyst in which Pt is supported but not Sb on the titania support, and carbon monoxide contained in the exhaust gas is filled. Heat exchange between an oxidation reactor to be oxidized, a pre-oxidation gas that is an exhaust gas before being processed in the oxidation reactor, and an oxidized gas that is an exhaust gas after being processed in the oxidation reactor; While cooling the oxidized gas, a heat exchanger for heating the pre-oxidation gas, a heater for heating the pre-oxidation gas after passing through the heat exchanger, and a gas heated by the heater A thermometer that detects the temperature, and a heating amount adjuster that adjusts a heating amount by the heater so that the temperature detected by the thermometer falls within a predetermined temperature range.

The catalyst of this exhaust gas treatment facility is a catalyst in which Pt is supported on a titania carrier. Therefore, in this exhaust gas treatment facility, even when sulfur oxide (hereinafter referred to as SOx) is contained in the exhaust gas, for example, the performance of the catalyst is better than that of a catalyst in which Pt is supported on an alumina carrier. Deterioration can be suppressed.

Also, in this exhaust gas treatment facility, when the temperature of the gas flowing into the oxidation reactor is low, this gas is heated by a heater, so even when the exhaust gas starts to flow into the exhaust gas treatment facility, A time lag from the start to the start of oxidation of CO contained in the exhaust gas can be suppressed. Furthermore, in this exhaust gas treatment facility, the amount of heating in the heater is controlled according to the temperature detected by the thermometer, so that CO can be oxidized continuously and stably. Furthermore, in this exhaust gas treatment facility, the amount of heating in the heater is adjusted according to the temperature detected by the thermometer, so if the temperature of the gas flowing into the oxidation reactor increases, the heating by the heater The amount is reduced. For this reason, in this exhaust gas treatment facility, the running cost can be suppressed.

Here, in the exhaust gas treatment facility, the heating amount controller is configured such that the temperature detected by the thermometer before the exhaust gas from the gas generation source that has started operating flows into the oxidation reactor. The amount of heating by the heater may be adjusted so that it falls within a predetermined temperature range.

In this exhaust gas treatment facility, since the amount of heating by the heater is adjusted before the exhaust gas from the gas generation source that has started operating flows into the oxidation reactor, the exhaust gas from the gas generation source that has started operating Immediately after starting to flow into the oxidation reactor, CO contained in the exhaust gas can be oxidized.

Further, in any one of the above exhaust gas treatment facilities, nitrogen oxides contained in the exhaust gas after being heated by the heater and before being cooled by the heat exchanger are reduced. A denitration device may be provided.
Further, in any one of the above exhaust gas treatment devices, the heat exchanger and the oxidation reactor are connected, and a first line for sending the pre-oxidation gas from the heat exchanger to the oxidation reactor, A second line that connects the oxidation reactor and the heat exchanger and sends the oxidized gas from the oxidation reactor to the heat exchanger, and the denitration device is in the first line or the second line It may be provided in two lines.

In this exhaust gas treatment facility, nitrogen oxides in the exhaust gas can be removed.

In the exhaust gas treatment facility including the denitration device, the denitration device treats the oxidized gas after being treated by the oxidation reactor and before being cooled by the heat exchanger, and the thermometer May detect the temperature of the gas after passing through the oxidation reactor and before flowing into the denitration apparatus.
Further, in the exhaust gas treatment facility comprising the first line and the second line, the denitration device is provided in the second line, and the thermometer is in the second line, It may be provided at a position closer to the oxidation reactor than the denitration device.

In this exhaust gas treatment device, by detecting the temperature of the gas flowing out from the oxidation reactor, the temperature for oxidizing the CO in the oxidation reactor can be controlled, and in addition, the denitration device can perform the denitration reaction. The temperature of the can also be managed.

In any one of the above exhaust gas treatment facilities provided with the denitration apparatus, the oxidation reactor may be filled with the Pt—Sb-based catalyst.

A Pt—Sb-based catalyst in which Pt and Sb are supported on a titania support has a lower SO ₂ oxidation rate than a Pt-based catalyst in which Pt is supported on a titania support and Sb is not supported. For this reason, in this exhaust gas treatment facility, oxidation of SO ₂ can be suppressed.

In the exhaust gas treatment facility including the denitration apparatus, the denitration apparatus is an ammonia denitration apparatus that ejects ammonia as a nitrogen oxide reducing agent into the exhaust gas, and the ammonia denitration apparatus is heated by the heater. The pre-oxidation gas after being processed and before being processed in the oxidation reactor may be processed.
Further, in the exhaust gas treatment facility including the first line and the second line, the denitration apparatus is an ammonia denitration apparatus that ejects ammonia as a nitrogen oxide reducing agent in the exhaust gas, The ammonia denitration apparatus may be provided in the first line and at a position closer to the oxidation reactor than the heater.

In an ammonia denitration apparatus, ammonia generally flows out from this denitration apparatus. The ammonia is preferably not released into the atmosphere. In this exhaust gas treatment facility, after the exhaust gas passes through the denitration device, it flows into the oxidation reactor. For this reason, in this exhaust gas treatment facility, the ammonia flowing out from the denitration apparatus can be converted into nitrogen by the oxidation reactor. As a result, acidic ammonium sulfate due to the reaction between ammonia and sulfur oxide is not generated, and corrosion of equipment and piping provided downstream of the denitration device can be suppressed by this acidic ammonium sulfate. Furthermore, the release of ammonia into the atmosphere can be suppressed.

In the exhaust gas treatment facility provided with an ammonia denitration device for treating the pre-oxidation gas before being treated in the oxidation reactor, the thermometer is heated by the heater and is supplied to the ammonia denitration device. You may detect the temperature of the gas before flowing in.

In this exhaust gas treatment facility, the temperature before flowing into the ammonia denitration device is detected, and by controlling this temperature to an appropriate temperature, the denitration device and the oxidation reactor can be operated efficiently.

The exhaust gas treatment facility as another aspect is
A denitration device that ejects ammonia as a nitrogen oxide reducing agent into exhaust gas to reduce the nitrogen oxide, and an oxidation reaction that oxidizes carbon monoxide contained in the exhaust gas treated by the denitration device The oxidation reactor is filled with a Pt—Sb catalyst in which Pt and Sb are supported on a titania support, or a Pt catalyst in which Pt is supported on a titania support and not Sb. ing.

This exhaust gas treatment facility can reduce nitrogen oxides contained in the exhaust gas and oxidize carbon monoxide contained in the exhaust gas. Further, in this exhaust gas treatment facility, the ammonia flowing out from the denitration device can be converted into nitrogen by the oxidation reactor. As a result, acidic ammonium sulfate due to the reaction between ammonia and sulfur oxide is not generated, and corrosion of equipment and piping provided downstream of the denitration device can be suppressed by this acidic ammonium sulfate. Furthermore, the release of ammonia into the atmosphere can be suppressed.

In the exhaust gas treatment facility as the other aspect, the pre-treatment gas which is the exhaust gas before being treated by the denitration apparatus and the oxidation reactor, and after being treated by the denitration apparatus and the oxidation reactor Heat exchange with the treated gas, which is the exhaust gas, cools the treated gas, while heating the pre-treated gas, and the pre-treated gas after passing through the heat exchanger You may provide the heater to heat and the heating amount regulator which adjusts the heating amount by the said heater.

In any one of the exhaust gas treatment facilities including the oxidation reactor and the denitration device, the exhaust gas treatment facility after being treated by the oxidation reactor and the denitration device and before being cooled by the heat exchanger. An exhaust heat recovery device may be provided that heats the first refrigerant while allowing the exhaust gas and the first refrigerant to exchange heat and cooling the exhaust gas.

In this exhaust gas treatment facility, unnecessary heat can be recovered from the heat generated in the oxidation reactor and used effectively.

In the exhaust gas treatment facility including the exhaust heat recovery device, when the temperature of the exhaust gas before heat exchange in the exhaust heat recovery device is lower than a predetermined temperature, the exhaust heat recovery device There may be provided a heat exchange limiter for restricting heat exchange between the exhaust gas and the first refrigerant.

If the temperature of the catalyst charged in the oxidation reactor becomes too high, the oxidation rate of SO ₂ increases and a large amount of SO ₃ is generated. For this reason, the generation of SO ₃ may cause corrosion of equipment and piping provided in the subsequent stage of the oxidation reactor and purple smoke from the chimney. In this exhaust gas treatment facility, when the temperature of the exhaust gas is lower than a predetermined temperature, heat exchange between the exhaust gas and the refrigerant in the exhaust heat recovery device is limited, and the temperature of the exhaust gas is determined in advance. When the temperature is equal to or higher than the temperature, heat exchange between the exhaust gas and the refrigerant in the exhaust heat recovery unit is performed. Therefore, in this exhaust gas treatment facility, the temperature increase of the catalyst more than necessary can be suppressed by heat exchange in the exhaust heat recovery device, and the generation of SO ₃ can be suppressed.

In any one of the above exhaust gas treatment facilities, the exhaust gas after being cooled by the heat exchanger and the second refrigerant are heat-exchanged to cool the exhaust gas while heating the second refrigerant. An exhaust heat recovery device may be provided.

In this exhaust gas treatment facility, the heat of the exhaust gas after being cooled by the heat exchanger can be recovered and used effectively.

Any of the above exhaust gas treatment facilities may include a dust collector that removes dust from the exhaust gas before being treated in the oxidation reactor.

An exhaust gas treatment method as one aspect for achieving the above object is as follows:
In the oxidation reactor, it is contained in the exhaust gas by a Pt—Sb-based catalyst in which Pt and Sb are supported on a titania support, or a Pt-based catalyst in which Pt is supported on a titania support but not Sb. Heat exchange between an oxidation treatment step for oxidizing carbon monoxide and a pre-oxidation gas that is an exhaust gas before being treated in the oxidation treatment step and an oxidized gas that is an exhaust gas after being treated in the oxidation treatment step A heat exchange step of heating the pre-oxidation gas while cooling the oxidized gas by a heat exchanger, and heating the pre-oxidation gas that has passed through the heat exchanger and heating the exhaust gas Adjusting the temperature of the exhaust gas such that the temperature of the exhaust gas falls within a predetermined temperature range.

In this exhaust gas treatment method, even when SOx is contained in the exhaust gas, for example, the catalyst performance deterioration can be suppressed more than that of a catalyst in which Pt is supported on an alumina carrier.

Also, in this exhaust gas treatment method, when the temperature of the pre-oxidation gas that has passed through the heat exchanger is low, this gas is heated, so even if the exhaust gas begins to flow into the exhaust gas treatment facility, A time lag from the start to the start of oxidation of CO contained in the exhaust gas can be suppressed. Furthermore, in this exhaust gas treatment method, the temperature of the exhaust gas is adjusted in the temperature adjustment step so as to be within a predetermined temperature range, so that CO can be oxidized stably and continuously. Furthermore, with this exhaust gas treatment facility, it is possible to suppress excessive heating in this temperature adjustment step, and it is possible to reduce running costs.

Here, in the exhaust gas processing method, in the temperature adjusting step, before the exhaust gas from the gas generation source that has started to operate flows into the oxidation reactor, before flowing into the oxidation reactor or before the oxidation The temperature of the gas may be adjusted so that the temperature of the gas flowing out from the reactor falls within the predetermined temperature range.

In any one of the exhaust gas treatment methods described above, the NOx removal apparatus removes nitrogen oxides contained in the exhaust gas after temperature adjustment in the temperature adjustment step and before cooling in the heat exchange step In the denitration step, the oxidized gas after being treated in the oxidation treatment step and before being cooled in the heat exchange step is treated, and in the temperature adjustment step, The temperature of the gas may be adjusted so that the gas before flowing out of the oxidation reactor and before flowing into the denitration apparatus falls within the predetermined temperature range.

Thereby, conventionally, in order to maintain the temperature of the denitration process at an appropriate temperature, a large amount of fuel for heating or the like has been used, but the amount of fuel or the like used can be suppressed.

In any one of the exhaust gas treatment methods described above, the NOx removal apparatus removes nitrogen oxides contained in the exhaust gas after temperature adjustment in the temperature adjustment step and before cooling in the heat exchange step In the denitration process, ammonia may be injected into the exhaust gas as a nitrogen oxide reducing agent to reduce the nitrogen oxide.

In the exhaust gas treatment method of ejecting ammonia into the exhaust gas in the denitration step, in the denitration step, after the temperature adjustment in the temperature adjustment step and before the treatment in the oxidation reactor, In the temperature adjustment step, the temperature of the gas is adjusted so that the gas after the temperature adjustment in the temperature adjustment step and before flowing into the denitration apparatus is within the predetermined temperature range. May be adjusted.

In this exhaust gas treatment method, the treatment in the denitration step and the oxidation treatment step can be performed efficiently by adjusting the temperature in the temperature adjustment step.

An exhaust gas treatment method as another aspect is as follows:
A denitration step in which ammonia is injected into the exhaust gas as a nitrogen oxide reducing agent to reduce the nitrogen oxide, and a catalyst in which Pt is supported on a titania carrier, into the exhaust gas treated in the denitration step. An oxidation treatment step of oxidizing the contained carbon monoxide.

In the exhaust gas treatment method as the other aspect, the pre-treatment gas which is the exhaust gas before being treated in the denitration step and the oxidation treatment step, and after being treated in the denitration step and the oxidation treatment step A heat exchanging step of heating the pre-treatment gas while cooling the treated gas by exchanging heat with the treated gas which is the exhaust gas may be included.

In any one of the exhaust gas treatment methods including the denitration step and the oxidation treatment step, the exhaust gas treatment method is performed after the treatment in the denitration step and the oxidation treatment step and before being cooled in the heat exchange step. An exhaust heat recovery step of heating the first refrigerant while cooling the exhaust gas while exchanging heat between the exhaust gas and the first refrigerant may be included.

In the exhaust gas treatment method including the exhaust heat recovery step, in the exhaust heat recovery step, the exhaust gas and the first refrigerant according to a temperature of the exhaust gas before heat exchange in the exhaust heat recovery step. The heat exchange with may be limited.

In any one of the above exhaust gas treatment methods, the exhaust gas after being cooled in the heat exchange step and the second refrigerant are heat-exchanged to cool the exhaust gas while heating the second refrigerant. An exhaust heat recovery step may be included.

In an exhaust gas treatment method as one aspect and an apparatus for executing this method, while suppressing running costs, the time lag from the start of inflow of exhaust gas to the start of oxidation treatment of carbon monoxide is suppressed, and then the monoxide is stably stabilized. Carbon can be oxidized.

It is a systematic diagram of the exhaust gas treatment facility according to the first embodiment. It is a graph which shows the relationship between the inlet temperature of a catalyst, and a CO combustion rate. It is a sequence diagram of the exhaust gas treatment facility according to the first embodiment. It is a systematic diagram of the exhaust gas treatment facility according to the second embodiment. Inlet temperature of the catalyst is a graph showing the SO ₂ oxidation rate characteristic of the catalyst in the case of 280 ° C.. Inlet temperature of the catalyst is a graph showing the SO ₂ oxidation rate characteristic of the catalyst in the case of 300 ° C.. It is a sequence diagram of the exhaust gas treatment facility according to the second embodiment. It is a systematic diagram of the exhaust gas treatment facility according to the third embodiment. Inlet temperature of the catalyst is a graph showing the NH ₃ conversion characteristics of the catalyst in the case of 280 ° C.. Inlet temperature of the catalyst is a graph showing the NH ₃ conversion characteristics of the catalyst in the case of 300 ° C.. It is a sequence diagram of the exhaust gas treatment facility according to the third embodiment. It is a systematic diagram of the exhaust gas treatment facility according to the fourth embodiment. It is a sequence diagram of the exhaust gas treatment facility according to the fourth embodiment. It is a systematic diagram of the exhaust gas treatment facility according to the fifth embodiment.

Hereinafter, various embodiments will be described in detail with reference to the drawings.

[First embodiment]
A first embodiment of an exhaust gas treatment facility will be described with reference to FIGS.

The exhaust gas processed by the exhaust gas processing facility of the present embodiment contains CO.

As shown in FIG. 1, the exhaust gas treatment facility 1 of the present embodiment includes an oxidation reactor 10 that oxidizes CO contained in the exhaust gas EX, and an exhaust gas EX before flowing into the oxidation reactor 10. A heat exchanger 15 for exchanging heat between a certain pre-treatment gas (or pre-oxidation gas) EXb and a treated gas (or oxidized gas) EXa that has flowed out of the oxidation reactor 10 and heating the exhaust gas EX A heater 20 that controls the amount of heating by the heater 20, and a thermometer 29 that detects the temperature of the exhaust gas EX.

The reaction vessel of the oxidation reactor 10 is filled with a catalyst 11 that oxidizes CO contained in the exhaust gas EX. The oxidation reactor 10 is formed with a pre-oxidation gas inlet 12 through which the pre-treatment gas EXb flows and an oxidized gas outlet 13 through which the treated gas EXa flows out.

The catalyst 11 filled in the reaction vessel of the oxidation reactor 10 is a catalyst in which Pt is supported on a titania (TiO ₂ ) support. As such a catalyst, for example, a Pt-based catalyst (Pt / TiO ₂ ) in which Pt is supported on a titania support and Sb is not supported, or a Pt—Sb-based catalyst in which Pt and Sb are supported on a titania support ( Pt—Sb / TiO ₂ ). The Pt-based catalyst is produced, for example, by impregnating anatase-type titanium oxide with a chloroplatinic acid solution and calcining it at about 500 ° C. The Pt—Sb-based catalyst is produced by calcining atatase type titanium oxide, chloroplatinic acid, water, hydrochloric acid, and antimony chloride at about 500 ° C. All of the above-mentioned methods of making the catalyst are known, and are described in detail, for example, in the above-mentioned Patent Document 1.

The heat exchanger 15 exchanges heat between the treated gas (or oxidized gas) EXa and the pre-treated gas (or pre-oxidized gas) EXb to cool the treated gas EXa, while heating the pre-treated gas EXb. To do. In this case, the processed gas EXa and the pre-processing gas EXb may be directly heat-exchanged, but the processed gas EXa and the pre-processing gas EXb may be heat-exchanged via an intermediate medium. The heat exchanger 15 includes a pre-treatment gas inlet 16 into which the pre-treatment gas EXb flows, a pre-treatment gas outlet 17 through which the pre-treatment gas EXb flows out, a treated gas inlet 18 into which the treated gas EXa flows in, and a treatment. A treated gas outlet 19 through which the gas EXa flows out is formed.

A pre-treatment gas line 41 is connected to the pre-treatment gas inlet 16 of the heat exchanger 15, and a second pre-treatment gas line 42 is connected to the pre-treatment gas outlet 17 of the heat exchanger 15. For example, an exhaust gas EX generation source is connected to the first pre-treatment gas line 41. The pre-oxidation gas inlet 12 of the oxidation reactor 10 is connected to the second pre-treatment gas line 42. A first treated gas line 43 is connected to the oxidized gas outlet 13 of the oxidation reactor 10. The processed gas inlet 18 of the heat exchanger 15 is connected to the first processed gas line 43. A second treated gas line 44 is connected to the treated gas outlet 19 of the heat exchanger 15. For example, a chimney is connected to the second treated gas line 44.

The heater 20 has a burner (hereinafter referred to as a burner 20) that injects coke oven gas (hereinafter referred to as COG (Coke Oven Gas)), which is a kind of flammable fluid. The heating amount adjuster 21 controls the valve opening degree of the COG flow rate adjusting valve 23 according to the temperature detected by the thermometer 29 and the COG flow rate adjusting valve 23 that adjusts the flow rate of COG that is a kind of flammable fluid. And a controller 24.

The burner 20 is provided in the second pre-treatment gas line 42 and injects COG into the line 42. The thermometer 29 is provided in the second pre-treatment gas line 42 and closer to the oxidation reactor 10 than the burner 20. The controller 24 controls the COG flow control valve 23 so that the temperature detected by the thermometer 29, that is, the temperature of the pre-treatment gas EXb immediately before flowing into the oxidation reactor 10 is within a predetermined temperature range. The valve opening is controlled.

In the oxidation reactor 10, an oxidation reaction represented by the following formula (1) proceeds by the catalyst 11, and CO becomes CO ₂ .
CO + 1 / 2O ₂ → CO ₂ (1)

Next, the CO oxidation rate by the catalyst 11, in other words, the CO combustion rate will be described with reference to FIG. 2 represents the temperature of the exhaust gas EX at the inlet of the oxidation reactor 10 (≈catalyst inlet temperature), and the vertical axis represents the CO combustion rate. The graph shown in FIG. 2 is obtained under the following conditions.
Exhaust gas flow rate: 220 [Nl / h-dry]
Process gas volume per unit gas contact surface of catalyst (AV): 62.5 [Nm ³ / (m ² · hr)]
CO: 7000 [ppm-dry]
SO ₂ : 10 [ppm-dry]
O ₂ : 13.1 [% -dry]
H ₂ O: 18 [% -wet]

As shown in FIG. 2, even when the catalyst 11 is a Pt—Sb catalyst (Pt—Sb / TiO ₂ ) (the plot is ◯), it is a Pt catalyst (Pt / TiO ₂ ) (in the diagram, Even if the plot is □), the oxidation reaction is performed when the temperature of the exhaust gas EX at the inlet of the oxidation reactor 10 is 200 or more. Further, a high CO combustion rate can be obtained when the temperature of the exhaust gas EX at the inlet of the oxidation reactor 10 is 240 ° C. or higher.

For this reason, in this embodiment, the temperature detected by the thermometer 29, that is, the temperature of the pre-treatment gas EXb immediately before flowing into the oxidation reactor 10 is, for example, within a temperature range of 240 ° C. or higher. The valve opening degree of the flow rate adjusting valve 23 is controlled by the controller 24.

Next, the operation of the exhaust gas treatment facility 1 will be described according to the sequence diagram shown in FIG.

When the operation start signal SS indicating the start of operation of the generation source of the exhaust gas EX is input to the controller 24 (S1), the controller 24 opens the COG flow control valve 23. The timing at which the COG flow rate adjusting valve 23 opens is before the generation source is operated and the exhaust gas EX from the generation source after operation actually flows into the oxidation reactor 10. When the COG flow control valve 23 is opened, COG is injected from the burner 20 into the second pre-treatment gas line 42, and this COG burns in the second pre-treatment gas line 42. The gas temperature in the second pre-treatment gas line 42 is increased by the combustion heat due to the combustion of this COG.

The temperature of the catalyst 11 before the start of operation of the exhaust gas EX generation source is less than 240 ° C., and is usually room temperature. On the other hand, as described above, the opening degree of the COG flow control valve 23 is such that the temperature detected by the thermometer 29, that is, the temperature of the pre-treatment gas EXb immediately before flowing into the oxidation reactor 10 is 240 ° C. or more, for example. It adjusts so that it may become (S2: Temperature control process). For this reason, immediately after the start of the operation of the exhaust gas EX generation source, the opening degree of the COG flow rate adjustment valve 23 increases, the COG flow rate injected from the burner 20 increases, and the temperature detected by the thermometer 29 increases. It grows rapidly. In other words, immediately after the start of operation of the exhaust gas EX generation source, the temperature of the catalyst 11 rapidly increases.

As the operation start signal SS indicating the start of operation of the exhaust gas EX generation source, for example, the control signal input by the operator to the controller 24 in conjunction with the operation of the exhaust gas EX generation source, the exhaust gas EX generation source is operated. For example, a flow rate signal indicating the flow rate of the exhaust gas EX at the source outlet, a concentration signal indicating the CO concentration of the exhaust gas EX at the source outlet, and the like. When a flow rate signal indicating the flow rate of the exhaust gas EX at the generation source outlet is used as the operation start signal SS, if the flow rate indicated by the flow rate signal is equal to or higher than a predetermined value, the generation source is treated as having started operation. In addition, when a concentration signal indicating the CO concentration at the source outlet is used as the operation start signal SS, if the CO concentration indicated by the concentration signal is equal to or greater than a predetermined value, it is treated that the generation source has started operation. Is called.

The pre-treatment gas EXb, which is the exhaust gas EX from the generation source, flows into the heat exchanger 15 from the pre-treatment gas inlet 16 of the heat exchanger 15 via the first pre-treatment gas line 41. Further, the gas from the oxidation reactor 10 flows into the heat exchanger 15 from the treated gas inlet 18 of the heat exchanger 15 through the first treated gas line 43. In the heat exchanger 15, the pre-treatment gas EXb and the gas from the oxidation reactor 10 are subjected to heat exchange, and the pre-treatment gas EXb is heated, while the gas from the oxidation reactor 10 is cooled (S3: heat). Exchange process). The gas from the oxidation reactor 10 cooled by the heat exchanger 15 is discharged to the atmosphere from a chimney or the like via the second treated gas line 44. The pre-treatment gas EXb heated by the heat exchanger 15 flows into the oxidation reactor 10 via the second pre-treatment gas line 42.

The pre-treatment gas EXb heated by the heat exchanger 15 is further heated by the combustion heat of COG while passing through the second pre-treatment gas line 42. Therefore, the pre-treatment gas EXb is heated by the heat exchanger 15 and the heater 20 and then flows into the oxidation reactor 10.

If the temperature of the pretreatment gas EXb that has flowed into the oxidation reactor 10 is 200 ° C. or higher, the reaction represented by the above-described formula (1) proceeds in the oxidation reactor 10 and the CO in the exhaust gas EX is reduced. It becomes CO ₂ (S4: oxidation treatment step).

Since the oxidation reaction in the oxidation reactor 10 is a reaction accompanied by heat generation, the temperature of the treated gas EXa flowing out from the oxidation reactor 10 is higher than the temperature of the pretreatment gas EXb just before flowing into the oxidation reactor 10. . The processed gas EXa flows into the heat exchanger 15 from the processed gas inlet 18 of the heat exchanger 15 through the first processed gas line 43. In the heat exchanger 15, as described above, the treated gas EXa and the pre-treatment gas EXb are heat-exchanged, and the pre-treatment gas EXb is heated, while the treated gas EXa is cooled (S3: Heat Exchange process). The treated gas EXa cooled by the heat exchanger 15 is discharged from the chimney or the like to the atmosphere via the second treated gas line 44.

As the reaction in the oxidation reactor 10 proceeds, the temperature of the treated gas EXa flowing out of the oxidation reactor 10 increases as the reaction proceeds. For this reason, in the heat exchanger 15, when the amount of heat transferred from the treated gas EXa to the pre-treatment gas EXb increases and the amount of gas heating by the combustion heat of the COG is approximately the same, the treatment before being heated by the combustion heat of the COG The temperature of the front gas EXb increases. If the temperature of the pretreatment gas EXb before being heated by the combustion heat of COG increases, the temperature detected by the thermometer 29 also increases.

When the temperature detected by the thermometer 29 gradually increases, the controller 24 gradually decreases the valve opening degree of the COG flow rate adjustment valve 23 according to the temperature increase (S2: temperature adjustment step). That is, the controller 24 controls the valve opening degree of the COG flow rate adjusting valve 23 according to the deviation between the temperature detected by the thermometer 29 and a certain temperature (240 ° C. in this case) within the appropriate temperature range. For this reason, when the temperature detected by the thermometer 29 gradually increases, the heating amount of the pre-treatment gas EXb due to the combustion heat of COG decreases. When the reaction is continuously performed in the oxidation reactor 10 and the temperature of the pretreatment gas EXb heated by the heat exchanger 15 becomes higher than, for example, 240 ° C., the COG flow control valve 23 is almost closed. In this case, COG is not substantially injected from the burner 20, and the pre-treatment gas EXb is not heated by the combustion heat of COG. That is, in this case, the temperature of the pre-treatment gas EXb is maintained at, for example, 240 ° C. or higher only with heat generated by the reaction in the oxidation reactor 10.

Even when the reaction in the oxidation reactor 10 is continuously performed, if the flow rate of the exhaust gas EX from the generation source varies, the COG flow rate control valve 23 may open. For example, immediately after the flow rate of the exhaust gas EX from the generation source decreases and the calorific value in the oxidation reactor 10 decreases, the flow rate of the exhaust gas EX from the generation source increases, and the heat exchanger 15 Even when the exhaust gas EX is heated, the temperature detected by the thermometer 29 may be lower than 240 ° C. In this case, the COG flow control valve 23 is opened, and the exhaust gas EX before flowing into the oxidation reactor 10 is heated by the combustion heat of COG (S2: temperature adjustment step).

As described above, in this embodiment, when the temperature of the gas flowing into the oxidation reactor 10 is low, the heater 20 heats this gas, so that the exhaust gas EX begins to flow into the exhaust gas treatment facility 1. Even in this case, the time lag from the start of inflow to the start of oxidation of CO contained in the exhaust gas EX can be suppressed. In addition, in this embodiment, the gas flowing into the oxidation reactor 10 is heated by the heater 20 before the exhaust gas EX starts to flow into the oxidation reactor 10, so that the exhaust gas immediately after the start of the flow of the exhaust gas EX. CO contained in EX can be oxidized.

In the present embodiment, the amount of heating in the heater 20 is controlled according to the temperature detected by the thermometer 29, so that CO can be continuously and stably oxidized. Furthermore, in this embodiment, the amount of heating in the heater 20, in other words, the valve opening degree of the COG flow rate adjusting valve 23 is controlled according to the temperature detected by the thermometer 29, so that it flows into the oxidation reactor 10. If the temperature of the gas to be increased, the flow rate of COG decreases. For this reason, in this embodiment, running cost can be held down.

Furthermore, the catalyst 11 of the present embodiment is a catalyst in which Pt is supported on a titania (TiO ₂ ) support. For this reason, in this embodiment, as described in the above-mentioned Patent Document 1, even when sulfur oxide (hereinafter referred to as SOx) is contained in the exhaust gas, for example, alumina (Al ₂ O ₃ ) The catalyst performance deterioration can be suppressed as compared with the catalyst in which Pt is supported on the carrier.

[Second Embodiment]
A second embodiment of the exhaust gas treatment facility will be described with reference to FIGS.

As shown in FIG. 4, the exhaust gas treatment facility 1a of the present embodiment is obtained by adding a denitration device 30 to the exhaust gas treatment facility 1 of the first embodiment.

The denitration apparatus 30 reduces nitrogen oxide (hereinafter referred to as NOx) in the exhaust gas to N ₂ and H ₂ O or the like. As a method for reducing NOx, there are an ammonia catalytic reduction method, an ammonia non-catalytic reduction method, a catalytic reduction method and the like. Both the ammonia catalytic reduction method and the ammonia non-catalytic reduction method are methods in which ammonia as a reducing agent is ejected into exhaust gas. On the other hand, the catalytic reduction method is a method of reducing NOx with an Ir-containing catalyst or the like without using ammonia. The reduction method employed in the present embodiment may be any of the above-described reduction methods, but here, an ammonia catalytic reduction method capable of reducing NOx at a relatively low temperature is employed.

A denitration apparatus 30 that employs an ammonia catalytic reduction method includes a reactor, a nozzle 32 that ejects ammonia into the reactor, and a catalyst 31 that is filled in the reactor. As a typical catalyst, for example, there is a catalyst in which titania (TiO ₂ ) is used as a carrier and V ₂ O 5, WO 3, or the like is supported thereon.

As in the first embodiment, the first pre-treatment gas line 41 is connected to the pre-treatment gas inlet 16 of the heat exchanger 15, and the second pre-treatment gas line is connected to the pre-treatment gas outlet 17 of the heat exchanger 15. 42 is connected. The pre-oxidation gas inlet 12 of the oxidation reactor 10 is connected to the second pre-treatment gas line 42. An oxidized gas line 45 is connected to the oxidized gas outlet 13 of the oxidation reactor 10. The oxidized gas line 45 is connected to a pre-denitration gas inlet 33 of the denitration apparatus 30. A first treated gas line 43 is connected to the denitrated gas outlet 34 of the denitration apparatus 30. The processed gas inlet 18 of the heat exchanger 15 is connected to the first processed gas line 43 as in the first embodiment. A second treated gas line 44 is connected to the treated gas outlet 19 of the heat exchanger 15.

As in the first embodiment, the burner 20 is provided in the second pre-treatment gas line 42 and injects COG into the line 42. The thermometer 29 is provided in the oxidized gas line 45 that connects the oxidation reactor 10 and the denitration apparatus 30. The controller 24 of the heating amount controller 21 controls the COG so that the temperature detected by the thermometer 29, that is, the temperature of the oxidized gas EXa1 immediately before flowing into the denitration apparatus 30 falls within a predetermined temperature range. The valve opening degree of the flow control valve 23 is controlled.

In the denitration apparatus 30 of the present embodiment, the reactions shown in the following formulas (2), (3), etc. proceed, and NOx becomes N ₂ , H ₂ O, and the like.
NO + NH ₃ + 1 / 4O ₂ → N ₂ + 3 / 2H ₂ O (2)
_{1 / 2NO + 1 / 2NO 2} + NH 3 → N 2 + 3 / 2H 2 O ········ (3)

For the above reaction, the temperature of the exhaust gas flowing into the denitration apparatus 30 and the temperature of the catalyst are preferably 280 ° C. or higher, for example. That is, when the temperature of the exhaust gas flowing into the denitration device 30 and the temperature of the catalyst are 280 ° C. or higher, the NOx reduction rate in the denitration device 30 increases. Furthermore, it is possible to suppress a decrease in catalyst performance due to acidic ammonium sulfate precipitation.

Therefore, in this embodiment, the COG flow rate is set so that the temperature detected by the thermometer 29, that is, the temperature of the oxidized gas EXa1 immediately before flowing into the denitration apparatus 30 is within a temperature range of, for example, 280 ° C. or higher. The valve opening degree of the control valve 23 is controlled by the controller 24. Also in the present embodiment, the controller 24 controls the valve opening degree of the COG flow rate adjusting valve 23 according to the deviation between the temperature detected by the thermometer 29 and a certain temperature (280 ° C. in this case) within the appropriate temperature range. To do.

By the way, in the oxidation reactor 10, CO in the exhaust gas is oxidized, and when the reaction temperature is high, SO ₂ in the exhaust gas may be oxidized to generate SO ₃ . This SO ₃ is preferably not released into the atmosphere. For this reason, it is preferable that SO ₂ is not oxidized in the oxidation reactor 10. In particular, when the denitration device 30 is provided on the downstream side of the oxidation reactor 10 as in the present embodiment, when SO ₃ generated in the oxidation reactor 10 flows into the denitration device 30, it is derived from sulfuric acid. Since the catalyst performance deteriorates, it is necessary to increase the NOx reduction reaction temperature in the denitration apparatus 30. Further, when the denitration apparatus 30 adopts the ammonia reduction method as in the present embodiment, when SO ₃ flows into the denitration apparatus 30, the SO ₃ and NH ₃ react to form the following formula ( As shown in 4), acidic ammonium sulfate is produced. This acidic ammonium sulfate corrodes the heat exchanger and the metal material forming each line. Therefore, it is preferable that the catalyst charged in the oxidation reactor 10 can suppress the oxidation of SO _{2 in} the exhaust gas.

2NH ₃ + SO ₃ + H ₂ O → (NH ₄ ) 2SO ₄ (4)

5 and 6 show SO ₂ oxidation rate characteristics of the Pt-based catalyst (Pt / TiO ₂ ) and the Pt—Sb-based catalyst (Pt—Sb / TiO ₂ ). In the figure, the horizontal axis represents the contact area of the catalyst per unit gas amount. Therefore, the horizontal axis represents the reciprocal of the amount of processing gas (AV) per unit gas contact surface of the catalyst. In the figure, the vertical axis represents the oxidation rate of SO ₂ .

As shown in FIG. 5, when the gas temperature at the catalyst inlet is 280 ° C., the contact area (1 / AV) of the catalyst per unit gas amount of the Pt—Sb catalyst (the plot is Δ) Even with this value, the oxidation rate of SO ₂ is substantially zero. On the other hand, in the Pt-based catalyst (the plot is ◇), the oxidation rate of SO ₂ increases as the contact area (1 / AV) of the catalyst per unit gas amount increases, for example, per unit gas amount When the contact area of the catalyst is 0.02 [(m ² · hr) / Nm ³ ], the oxidation rate of SO ₂ exceeds 25 [%].

In addition, as shown in FIG. 6, even when the gas temperature at the catalyst inlet is 300 ° C., the Pt—Sb-based catalyst (in the figure, the plot is Δ) is the catalyst contact area per unit gas amount (1 / AV ) Is any value, the oxidation rate of SO ₂ is substantially zero. On the other hand, in the Pt-based catalyst (the plot is ◇), the oxidation rate of SO ₂ increases as the contact area (1 / AV) of the catalyst per unit gas amount increases, for example, per unit gas amount When the contact area of the catalyst is 0.02 [(m ² · hr) / Nm ³ ], the oxidation rate of SO ₂ exceeds 25 [%].

As described above, from the viewpoint of suppressing the oxidation of SO _{2 in} the oxidation reactor 10, the catalyst charged in the oxidation reactor 10 is preferably a Pt—Sb-based catalyst (Pt—Sb / TiO ₂ ). Therefore, in this embodiment, a Pt—Sb-based catalyst (Pt—Sb / TiO ₂ ) is used as the catalyst 11 filled in the oxidation reactor 10.

Next, the operation of the exhaust gas treatment facility 1a will be described according to the sequence diagram shown in FIG.

Also in the exhaust gas treatment facility 1a of this embodiment, when the operation start signal SS is input to the controller 24 of the COG flow control valve 23 (S1), as in the exhaust gas treatment facility 1 of the first embodiment, the COG flow control valve. 23 opens and the temperature adjustment step (S2a) is started. The timing when the COG flow rate adjusting valve 23 opens is also before the exhaust gas EX from the generated source is actually flown into the oxidation reactor 10 after the generation source is operated, as in the first embodiment.

However, in the temperature adjustment step (S2a) of the present embodiment, the valve opening degree of the COG flow rate adjustment valve 23 is the temperature detected by the thermometer 29, that is, the temperature of the oxidized gas EXa1 just before flowing into the denitration device 30. Is controlled by the controller 24 so as to be, for example, 280 ° C. or higher. Therefore, when this temperature control step (S2a) is started before the generation source is operated and the exhaust gas EX from the operation source after the operation actually flows into the oxidation reactor 10, the denitration device 30 is more influential. The inside of the oxidation reactor 10 arranged on the upstream side is inevitably adjusted to be 280 ° C. or higher. Further, even if the exhaust gas EX from the generation source actually starts to flow into the oxidation reactor 10 and the oxidation reaction is started in the oxidation reactor 10, the temperature of the exhaust gas flowing into the oxidation reactor 10 is basically The temperature is adjusted to 240 ° C. or higher. That is, in the temperature adjustment step (S2a) of the present embodiment, even when the temperature of the oxidized gas EXa1 immediately before flowing into the denitration device 30 is adjusted to be 280 ° C. or higher, for example, the exhaust gas flowing into the oxidation reactor The temperature is adjusted to 240 ° C. or higher as in the first embodiment.

Further, in the exhaust gas treatment facility 1a of the present embodiment, as in the exhaust gas treatment facility 1 of the first embodiment, the heat exchange step (S3) by the heat exchanger 15 and the oxidation treatment step (S4) by the oxidation reactor 10 are performed. Is executed.

Further, the exhaust gas treatment facility 1a of the present embodiment has a relationship in which the denitration device 30 is added to the exhaust gas treatment facility 1 of the first embodiment, and thus the denitration step (S5) by the denitration device 30 is executed. . That is, the oxidized gas EXa1 that has flowed out of the oxidation reactor 10 flows into the denitration apparatus 30, and NOx contained in the oxidized gas EXa1 is reduced in the denitration apparatus 30, and this NOx is converted into N ₂ and H ₂ O or the like (S5: denitration step).

The exhaust gas EX in which CO in the exhaust gas EX is oxidized and NOx in the exhaust gas EX is reduced is treated as a treated gas (oxidized and denitrated gas) EXa2 as in the first embodiment. It flows into the heat exchanger 15 from the treated gas inlet 18 of the heat exchanger 15 through the spent gas line 43. In the heat exchanger 15, as in the first embodiment, the treated gas EXa2 and the pre-treatment gas (pre-oxidation and pre-denitration gas) EXb are heat-exchanged, and the pre-treatment gas EXb is heated, The spent gas EXa2 is cooled (S3: heat exchange step). The treated gas EXa2 cooled by the heat exchanger 15 is discharged from the chimney or the like to the atmosphere via the second treated gas line 44.

As described above, in the present embodiment, when the temperature of the gas flowing into the oxidation reactor 10 and the denitration apparatus 30 is low, the gas is heated by the heater 20, so that the exhaust gas EX is the exhaust gas processing facility 1a. Even when starting to flow in, the time lag from the start of inflow to the start of oxidation of CO contained in the exhaust gas EX can be suppressed. Further, in the present embodiment, when the exhaust gas EX starts to flow into the exhaust gas processing facility 1a, it is possible to suppress a time lag from the start of inflow to the start of reduction of NOx contained in the exhaust gas EX. Moreover, in the present embodiment, the gas flowing into the oxidation reactor 10 and the denitration device 30 is heated by the heater 20 before the exhaust gas EX begins to flow into the oxidation reactor 10 and the denitration device 30, so the exhaust gas EX Immediately after the start of inflow, CO contained in the exhaust gas EX can be oxidized and NOx can be reduced.

In the present embodiment, since the heating amount in the heater 20 is controlled according to the temperature detected by the thermometer 29, CO can be continuously oxidized stably and NOx can be continuously increased. Can be stably reduced. Further, in the present embodiment, the amount of heating in the heater 20, in other words, the valve opening degree of the COG flow rate adjusting valve 23 is controlled according to the temperature detected by the thermometer 29, so that the oxidation reactor 10 and the denitration are controlled. If the temperature flowing into the device 30 increases, the flow rate of COG decreases. For this reason, running cost can be held down also in this embodiment.

In this embodiment, the thermometer 29 is provided in the oxidized gas line 45 that connects the oxidation reactor 10 and the denitration device 30. However, similarly to the first embodiment, the thermometer 29 may be provided in the second pre-treatment gas line 42 at a position closer to the oxidation reactor 10 than the heater 20.

[Third embodiment]
A third embodiment of the exhaust gas treatment facility will be described with reference to FIGS.

As shown in FIG. 8, the exhaust gas treatment facility 1b of the present embodiment is also obtained by adding a denitration device 30 to the exhaust gas treatment facility 1 of the first embodiment, as in the second embodiment. However, in the second embodiment, the denitration device 30 is provided on the downstream side of the oxidation reactor, but in this embodiment, the denitration device 30 is provided on the upstream side of the oxidation reactor 10.

The denitration apparatus 30 of this embodiment is also an apparatus that employs an ammonia catalytic reduction method, like the denitration apparatus 30 of the second embodiment.

As in the first embodiment, the first pre-treatment gas line 41 is connected to the pre-treatment gas inlet 16 of the heat exchanger 15, and the second pre-treatment gas line is connected to the pre-treatment gas outlet 17 of the heat exchanger 15. 42 is connected. The pre-denitration gas inlet 33 of the denitration apparatus 30 is connected to the second pretreatment gas line 42. A denitrated gas line 46 is connected to the denitrated gas outlet 34 of the denitration apparatus 30. The pre-oxidation gas inlet 12 of the oxidation reactor 10 is connected to the denitrated gas line 46. A first treated gas line 43 is connected to the oxidized gas outlet 13 of the oxidation reactor 10. The processed gas inlet 18 of the heat exchanger 15 is connected to the first processed gas line 43 as in the first and second embodiments. A second treated gas line 44 is connected to the treated gas outlet 19 of the heat exchanger 15.

The burner 20 is provided in the second pre-treatment gas line 42 as in the first and second embodiments, and injects COG into the line 42. The thermometer 29 is provided in the second pre-treatment gas line 42 and closer to the denitration device 30 than the burner 20. The controller 24 controls the valve of the COG flow rate adjusting valve 23 so that the temperature detected by the thermometer 29, that is, the temperature of the pre-treatment gas EXb1 immediately before flowing into the denitration apparatus 30 falls within a predetermined temperature range. Opening is controlled. Specifically, the controller 24 of the present embodiment controls the valve opening degree of the COG flow rate adjustment valve 23 so as to be within a temperature range of 280 ° C. or higher.

Incidentally, in the denitration apparatus 30 that employs the ammonia reduction method, ammonia flows out from the denitration apparatus 30 due to catalyst deterioration, partial catalyst blockage, or the like. The ammonia is preferably not released into the atmosphere.

9 and 10 show NH ₃ conversion characteristics of a Pt-based catalyst (Pt / TiO ₂ ) and a Pt—Sb-based catalyst (Pt—Sb / TiO ₂ ). In the figure, the horizontal axis represents the contact area of the catalyst per unit gas amount. Therefore, the horizontal axis represents the reciprocal of the amount of processing gas (AV) per unit gas contact surface of the catalyst. In the figure, the vertical axis represents the conversion rate of NH ₃ .

Here, conversion of NH ₃ is conversion of NH ₃ to N ₂ as shown in the following formula (5).
2NH ₃ + 3 / 2O ₂ → N ₂ + 3H ₂ O (5)

As shown in FIG. 9, when the gas temperature at the catalyst inlet is 280 ° C., the contact area (1 / AV) of the catalyst per unit gas amount is 0 for the Pt—Sb catalyst (the plot is Δ). If not [(m ² · hr) / Nm ³ ], in other words, if a catalyst is present, NH ₃ can be converted to N ₂ . In addition, the Pt-based catalyst (the plot is ◇) also has a catalyst contact area (1 / AV) per unit gas amount of 0 [(m ² · hr) / Nm ³ ]. If present, NH ₃ can be converted to N ₂ . Moreover, NH ₃ conversion of Pt-based catalyst is higher than the NH ₃ conversion of Pt-Sb-based catalyst. Further, in both the Pt-based catalyst and the Pt—Sb-based catalyst, the NH ₃ conversion rate increases as the contact area (1 / AV) of the catalyst per unit gas amount increases.

As shown in FIG. 10, when the gas temperature at the catalyst inlet is 300 ° C., the contact area (1 / AV) of the catalyst per unit gas amount is 0 for the Pt—Sb catalyst (the plot is Δ). Unless it is [(m ² · hr) / Nm ³ ] or more, NH ₃ can be converted to N ₂ . In addition, the Pt-based catalyst (the plot is ◇) also shows that NH ₃ is N if the catalyst contact area per unit gas amount (1 / AV) is not 0 [(m ² · hr) / Nm ³ ]. Can be converted to ₂ . Also, when the gas temperature at the catalyst inlet is 300 ° C., both the Pt-based catalyst and the Pt—Sb-based catalyst are the catalyst per unit gas amount, as in the case where the gas temperature at the catalyst inlet is 280 ° C. As the contact area (1 / AV) increases, the NH ₃ conversion increases. When the gas temperature at the catalyst inlet is 300 ° C., the NH ₃ conversion rate of the Pt—Sb-based catalyst is higher at 300 ° C. than when the gas temperature at the catalyst inlet is 280 ° C. On the other hand, the NH ₃ conversion rate of the Pt-based catalyst is almost the same when the gas temperature at the catalyst inlet is 280 ° C. and when it is 300 ° C. Therefore, when the gas temperature at the catalyst inlet of 300 ° C., NH ₃ conversion of Pt-Sb-based catalyst, is substantially the same as the NH ₃ conversion of Pt based catalyst.

Therefore, the catalyst 11 filled in the oxidation reactor 10 may be a Pt—Sb catalyst or a Pt catalyst. However, when importance is attached to the conversion of NH ₃ to N ₂ , a Pt-based catalyst is preferable to a Pt—Sb-based catalyst.

However, even when importance is attached to the conversion of NH ₃ to N ₂ , a Pt—Sb-based catalyst is employed as the catalyst 11 to be charged in the oxidation reactor 10 under the condition that the gas temperature at the catalyst inlet is increased. Also good. In addition, as described above, this Pt—Sb-based catalyst can suppress the oxidation of SO ₂ . Therefore, whether the Pt—Sb catalyst or the Pt—Sb catalyst is used as the catalyst 11 charged in the oxidation reactor 10 is determined by comparing the NH ₃ conversion rate and the SO ₂ oxidation rate. Is preferably determined.

Next, the operation of the exhaust gas treatment facility 1b will be described according to the sequence diagram shown in FIG.

In the exhaust gas treatment facility 1b of this embodiment, as in the first and second embodiments, when the operation start signal SS is input to the controller 24 of the COG flow control valve 23 (S1), the COG flow control valve 23 opens, The temperature adjustment step (S2b) is started. Similarly to the first and second embodiments, the timing at which the COG flow rate control valve 23 opens is also before the exhaust gas EX from the generated source is actually flown into the oxidation reactor 10 after the generation source is operated. is there.

However, in the temperature adjustment step (S2b) of the present embodiment, the valve opening degree of the COG flow rate adjustment valve 23 is the temperature detected by the thermometer 29, that is, the temperature of the pre-treatment gas EXb1 flowing into the denitration apparatus 30 is, for example, The controller 24 controls the temperature to be 280 ° C. or higher.

Further, in the exhaust gas treatment facility 1b of the present embodiment, similarly to the exhaust gas treatment facility 1a of the second embodiment, the heat exchange step (S3) by the heat exchanger 15, the denitration step (S5b) by the denitration device 30, and the oxidation An oxidation treatment step (S4b) by the reactor 10 is performed.

In this embodiment, the pre-treatment gas (pre-oxidation and pre-denitration gas) EXb1 flows into the denitration apparatus 30, and NOx contained in the pre-treatment gas EXb1 is reduced (S5b: denitration step). The denitrated gas EXb2, which is the exhaust gas denitrated by the denitration apparatus 30, flows into the oxidation reactor 10, and the CO contained in the denitrated gas EXb2 is oxidized (S4b: oxidation process step). In the temperature adjustment step (2b) of the present embodiment, as described above, the temperature of the pretreatment gas EXb1 flowing into the denitration apparatus 30 is adjusted to be 280 ° C. or higher, for example. For this reason, in the temperature adjustment step (2b) of the present embodiment, the temperature of the denitrated gas EXb2 from the denitration device 30 flowing into the oxidation reactor 10 is basically adjusted to 240 ° C. or higher.

As described above, also in the present embodiment, as in the second embodiment, the time lag until the oxidation of CO contained in the exhaust gas EX is started and the reduction of NOx contained in the exhaust gas EX is started. Time lag can be suppressed. Also in this embodiment, CO can be continuously and stably oxidized, and NOx can be continuously and stably reduced. Furthermore, also in this embodiment, the amount of COG used can be reduced and the running cost can be suppressed.

Further, in this embodiment, the denitration-treated gas EXb2 after the treatment in the denitration step (S5b) is treated in the oxidation treatment step (S4b). That is, in the present embodiment, the oxidation reactor 10 filled with the Pt—Sb catalyst or the Pt catalyst is disposed downstream of the denitration apparatus 30 that employs the ammonia reduction method. Therefore, in the present embodiment, ammonia flowing out from the denitration apparatus 30 can be converted into N ₂ by the oxidation reactor 10. For this reason, in this embodiment, the atmospheric release amount of ammonia injected in the denitration apparatus 30 can be suppressed.

[Fourth embodiment]
A fourth embodiment of the exhaust gas treatment facility will be described with reference to FIGS.

As shown in FIG. 12, the exhaust gas treatment facility 1c of this embodiment is a modification of the exhaust gas treatment facility 1b of the third embodiment, and the exhaust gas treatment facility 1b includes a first exhaust heat recovery device 35 and a second exhaust heat recovery device 35. An exhaust heat recovery device 49 is added.

The first exhaust heat recovery unit 35 is a heat exchanger that heats the first refrigerant CM1 while cooling the processed gas EXa2 by exchanging heat between the processed gas EXa2 and the first refrigerant CM1. The first exhaust heat recovery unit 35 is provided in the first treated gas line 43. The exhaust gas treatment facility 1c of this embodiment further includes a heat exchange limiter 36 that restricts heat exchange between the processed gas EXa2 and the first refrigerant CM1 in the first exhaust heat recovery device 35. This heat exchange limiter 36 is oxidized in the refrigerant flow rate adjustment valve 37 that adjusts the flow rate of the first refrigerant CM1 that passes through the refrigerant line connected to the first exhaust heat recovery unit 35, and in the first treated gas line 43. A thermometer 39 provided between the reactor 10 and the first exhaust heat recovery unit 35 and a controller 38 are provided. The opening degree of the refrigerant flow control valve 37 is controlled by the controller 38 according to the temperature detected by the thermometer 39.

The second exhaust heat recovery device 49 is a heat exchanger that heats the second refrigerant CM2 while cooling the processed gas EXa2 by exchanging heat between the processed gas EXa2 and the second refrigerant CM2. The second exhaust heat recovery device 49 is provided in the second processed gas line 44.

Next, the operation of the exhaust gas treatment facility 1c will be described according to the sequence diagram shown in FIG. Also in the present embodiment, as in the third embodiment, the temperature adjustment step (S2b) by the heating amount controller 21, the heat exchange step (S3) by the heat exchanger 15, the denitration step (S5b) by the denitration device 30, and the oxidation reaction An oxidation treatment step (S4b) by the vessel 10 is performed.

Furthermore, in this embodiment, the 1st waste heat recovery process (S6) by the 1st waste heat recovery device 35 and the 2nd waste heat recovery process (S7) by the 2nd waste heat recovery device 49 are also performed.

As described above, when the oxidation reaction is started in the oxidation reactor 10 and the temperature detected by the thermometer 29 reaches a predetermined temperature, the COG flow rate control valve 23 is completely closed and is processed by the heater 20. The front gas EXb1 is not heated. However, if the oxidation reaction further proceeds in the oxidation reactor 10, the amount of heat generated in the oxidation reactor 10 increases. As a result, the temperature of the exhaust gas flowing into the oxidation reactor 10 and the denitration device 30 also increases. As for the catalyst with which the oxidation reactor 10 is filled, and the catalyst with which the denitration apparatus 30 is filled, the gas processing capacity increases as the temperature increases. However, if the temperature of the catalyst becomes too high, the gas processing capacity is lowered and the deterioration of the catalyst is accelerated.

Therefore, in the present embodiment, when the temperature detected by the thermometer 39, that is, the temperature of the processed gas EXa2, reaches a predetermined temperature (for example, 350 ° C.), the controller 38 opens the refrigerant flow rate adjustment valve 37, and One exhaust heat recovery device 35 exchanges heat between the processed gas EXa2 and the first refrigerant CM1 (S6: first exhaust heat recovery step). As a result, the processed gas EXa2 is cooled, while the first refrigerant CM1 is heated. The heat of the heated first refrigerant CM1 is used as appropriate. In the present embodiment, if the temperature detected by the thermometer 39 is lower than a predetermined temperature (for example, 350 ° C.), the refrigerant flow rate adjustment valve 37 is closed, and the gas that has been processed by the first exhaust heat recovery device 35 is closed. Heat exchange between EXa2 and the first refrigerant CM1 is not performed.

Suppose that the temperature of the pre-treatment gas EXb1 immediately before flowing into the denitration apparatus 30 is 280 ° C. In this case, even if the treated gas EXa2 is cooled by the heat exchanger 15, the temperature of the treated gas EXa2 after being cooled by the heat exchanger 15 is around 200 ° C. Therefore, in the present embodiment, the heat of the processed gas EXa2 is recovered by the second exhaust heat recovery device 49 to make effective use of this heat.

As described above, in the present embodiment, unnecessary heat out of the heat generated in the oxidation reactor 10 can be recovered and effectively used.

In this embodiment, in addition to the thermometer 29 for opening and closing the COG flow rate adjusting valve 23, a thermometer 39 for opening and closing the refrigerant flow rate adjusting valve 37 is provided separately, and the temperature detected by the thermometer 39 is detected. In response to this, the opening and closing of the refrigerant flow control valve 37 is controlled. However, the opening / closing of the refrigerant flow rate adjustment valve 37 may be controlled according to the temperature detected by the thermometer 29 for opening / closing the COG flow rate adjustment valve 23.

In this embodiment, the heat exchange between the processed gas EXa2 and the first refrigerant CM1 is limited by opening and closing the refrigerant flow rate adjustment valve 37 provided in the refrigerant line. However, a bypass line that bypasses the first exhaust heat recovery device 35 is provided in the first treated gas line 43, and a bypass flow rate adjustment valve is provided in the bypass line, and the treated gas EXa2 is opened and closed by opening and closing the bypass flow rate adjustment valve. And heat exchange between the first refrigerant CM1 and the first refrigerant CM1 may be limited. In this case, if the temperature detected by the thermometer 39 is lower than a predetermined temperature (for example, 350 ° C.), the bypass flow rate adjustment valve is opened and the processed gas EXa2 and the first refrigerant CM1 by the first exhaust heat recovery device 35 are opened. Limit heat exchange with.

In the present embodiment, the exhaust gas treatment facility 1b of the third embodiment is provided with a first exhaust heat recovery device 35, a second exhaust heat recovery device 49, and the like. However, only one of the first exhaust heat recovery unit 35 and the second exhaust heat recovery unit 49 may be provided.

Although this embodiment is a modification of the third embodiment, the first exhaust heat recovery device in this embodiment is added to the exhaust gas treatment facility 1 of the first embodiment or the exhaust gas treatment facility 1a of the second embodiment. One or both of 35 and the second exhaust heat recovery unit 49 may be added.

Each of the heaters 20 in each of the above embodiments injects COG and heats the gas with the combustion heat of this COG. However, the heater may inject a combustible fluid other than COG and heat the gas with the combustion heat of the combustible fluid. Further, the gas may be heated by heat generated by an electric heater without using a flammable fluid. Further, the thermometer may be in any form as long as it can detect the temperature, and may be a thermocouple, a thin film temperature sensor, a laser temperature measuring instrument, or the like.

"Fifth embodiment"
A fifth embodiment of the exhaust gas treatment facility will be described with reference to FIG.

Many steel mills have a sintering furnace 51 that mixes lime with iron ore as a raw material to produce sintered ore 57 that is an agglomeration of ore, and a coke furnace 52 that steams and burns coal to produce coke 58. And a blast furnace 53 in which the coke 58 is put into the sintered ore 57 and iron content in the sintered ore 57 is taken out, and an exhaust gas processing facility for processing the exhaust gas EX from the sintering furnace 51 is provided. The exhaust gas treatment facility 1d of the present embodiment is an exhaust gas treatment facility in this steelworks.

The exhaust gas treatment facility 1d according to the present embodiment includes an exhaust gas treatment facility 1c according to the fourth embodiment, an exhaust gas line 56 through which the exhaust gas EX from the sintering furnace 51 flows, and the exhaust gas treatment facility 1c. A dust collector 54 and a desulfurization device 55 provided in the gas line 56.

The exhaust gas line 56 is connected to the first pretreatment gas line 41 in the exhaust gas treatment facility 1c. The dust collector 54 may be either a wet type dust collector or a dry type dust collector. Further, as the dust collector 54, both a wet type dust collector and a dry type dust collector may be provided.

The desulfurization device 55 is a device that, for example, wet-treats the exhaust gas EX using limestone as an absorbent and takes out SOx reacted with the limestone as gypsum.

In the exhaust gas treatment facility 1d of this embodiment, dust is removed from the exhaust gas EX by the dust collector 54, and the SOx content in the exhaust gas EX is removed by the desulfurizer 55. Thereafter, NOx in the exhaust gas EX is reduced by the denitration device 30 of the exhaust gas treatment facility 1c in the fourth embodiment. Subsequently, CO in the exhaust gas EX is oxidized in the oxidation reactor 10 of the exhaust gas treatment facility 1c in the fourth embodiment and then released from the chimney 59 to the atmosphere.

The COG generated in the coke oven 52 is supplied to the burner 20 of the exhaust gas treatment facility 1d of the present embodiment.

The exhaust gas treatment facility 1d of this embodiment is obtained by adding a dust collector 54, a desulfurization device 55, and the like to the exhaust gas treatment facility 1c in the fourth embodiment. However, a dust collector 54, a desulfurization device 55, etc. are added to the exhaust

gas treatment facilities

1, 1a, 1b in the first to third embodiments, and the configuration is the same as that of the exhaust gas treatment facility 1d of the present embodiment. Good.

The exhaust gas treatment facility 1d of the present embodiment is for treating the exhaust gas EX from the sintering furnace 51 of the steel mill. However, when CO is contained in the exhaust gas EX, the exhaust gas processing facility in each of the above embodiments may process the exhaust gas EX from a gas generation source other than the sintering furnace 51.

In one aspect according to the present invention, it is possible to suppress the time lag from the start of the inflow of exhaust gas to the start of the oxidation treatment of carbon monoxide while suppressing the running cost and stably oxidize carbon monoxide thereafter.

1, 1a, 1b, 1c, 1d: exhaust gas treatment equipment, 10: oxidation reactor, 11: catalyst, 12: pre-oxidation gas inlet, 13: oxidized gas outlet, 15: heat exchanger, 20: heater or Burner, 21: Heating amount regulator, 23: COG flow rate regulating valve, 24: Controller, 29: Thermometer, 30: Denitration device, 31: Catalyst, 33: Gas inlet before denitration, 34: Denitrated gas outlet, 35 : First exhaust heat recovery device, 36: Heat exchange limiter, 38: Controller, 39: Thermometer, 41: Gas line before the first treatment, 42: Gas line before the second treatment, 43: First treated gas Line: 44: Second treated gas line, 45: Oxidized gas line, 46: Denitrated gas line, 49: Second exhaust heat recovery device, 54: Dust collector, 55: Desulfurizer, 59: Chimney, EX : Exhaust gas, EXa, EXa2: treated gas (oxidized) EXa1: Oxidized gas, EXb, EXb1: Gas before treatment (gas before denitration before oxidation), EXb2: Denitrated gas, SS: Operation start signal

Claims

The Pt-Sb catalyst in which Pt and Sb are supported on the titania support, or the Pt catalyst in which Pt is supported but not Sb on the titania support, and carbon monoxide contained in the exhaust gas is filled. An oxidation reactor to oxidize,
While the pre-oxidation gas that is the exhaust gas before being processed in the oxidation reactor and the oxidized gas that is the exhaust gas after being processed in the oxidation reactor are heat-exchanged, the oxidized gas is cooled And a heat exchanger for heating the pre-oxidation gas,
A heater for heating the pre-oxidation gas after passing through the heat exchanger;
A thermometer for detecting the temperature of the gas heated by the heater;
A heating amount adjuster for adjusting the heating amount by the heater so that the temperature detected by the thermometer is within a predetermined temperature range;
An exhaust gas treatment facility comprising:
The exhaust gas treatment facility according to claim 1,
The heating amount adjuster is configured so that the temperature detected by the thermometer is within the predetermined temperature range before the exhaust gas from the gas generation source that has started operating flows into the oxidation reactor. Adjusting the amount of heating by the heater;
Exhaust gas treatment equipment.
The exhaust gas treatment facility according to claim 1 or 2,
A denitration device for reducing nitrogen oxides contained in the exhaust gas after being heated by the heater and before being cooled by the heat exchanger;
Exhaust gas treatment equipment.
The exhaust gas treatment facility according to claim 3,
The denitration apparatus processes the oxidized gas after being processed by the oxidation reactor and before being cooled by the heat exchanger,
The thermometer detects the temperature of the gas after passing through the oxidation reactor and before flowing into the denitration device,
Exhaust gas treatment equipment.
The exhaust gas treatment facility according to claim 4,
The oxidation reactor is filled with the Pt—Sb catalyst.
Exhaust gas treatment equipment.
The exhaust gas treatment facility according to claim 3,
The denitration device is an ammonia denitration device that ejects ammonia into the exhaust gas as a nitrogen oxide reducing agent,
The ammonia denitration apparatus treats the pre-oxidation gas after being heated by the heater and before being treated in the oxidation reactor,
Exhaust gas treatment equipment.
The exhaust gas treatment facility according to claim 6,
The thermometer detects the temperature of the gas after being heated by the heater and before flowing into the ammonia denitration device,
Exhaust gas treatment equipment.
A denitration device for injecting ammonia into the exhaust gas as a nitrogen oxide reducing agent to reduce the nitrogen oxide;
An oxidation reactor that oxidizes carbon monoxide contained in the exhaust gas treated by the denitration device;
With
The oxidation reactor is filled with a Pt—Sb-based catalyst in which Pt and Sb are supported on a titania support, or a Pt-based catalyst in which Pt is supported on a titania support but not Sb.
Exhaust gas treatment equipment.
The exhaust gas treatment facility according to claim 8,
Heat exchange is performed between the pre-treatment gas, which is the exhaust gas before being processed in the denitration apparatus and the oxidation reactor, and the treated gas, which is the exhaust gas after being processed in the denitration apparatus and the oxidation reactor. A heat exchanger for cooling the treated gas while heating the pre-treated gas;
A heater for heating the pre-treatment gas after passing through the heat exchanger;
A heating amount adjuster for adjusting a heating amount by the heater;
An exhaust gas treatment facility comprising:
The exhaust gas treatment facility according to any one of claims 3 to 7, wherein
The exhaust gas after being processed by the oxidation reactor and the denitration apparatus and before being cooled by the heat exchanger is heat-exchanged with the first refrigerant to cool the exhaust gas, A waste heat recovery device for heating one refrigerant;
Exhaust gas treatment equipment.
The exhaust gas treatment facility according to claim 10,
When the temperature of the exhaust gas before heat exchange in the exhaust heat recovery device is lower than a predetermined temperature, heat exchange between the exhaust gas and the first refrigerant in the exhaust heat recovery device is performed. With a heat exchanger restrictor to restrict,
Exhaust gas treatment equipment.
The exhaust gas treatment facility according to any one of claims 1 to 7, 9 to 11,
The exhaust gas after being cooled by the heat exchanger and the second refrigerant are heat-exchanged, and the exhaust gas is cooled, while being provided with an exhaust heat recovery unit that heats the second refrigerant.
Exhaust gas treatment equipment.
The exhaust gas treatment facility according to any one of claims 1 to 12,
A dust collector for removing dust from the exhaust gas before being treated in the oxidation reactor;
Exhaust gas treatment equipment.
In the oxidation reactor, it is contained in the exhaust gas by a Pt—Sb-based catalyst in which Pt and Sb are supported on a titania support, or a Pt-based catalyst in which Pt is supported on a titania support but not Sb. An oxidation treatment step of oxidizing carbon monoxide;
A heat exchanger exchanges heat between the pre-oxidation gas that is the exhaust gas before being treated in the oxidation treatment step and the oxidized gas that is the exhaust gas after the treatment in the oxidation treatment step, and the oxidized gas A heat exchange step of heating the pre-oxidation gas while cooling
A temperature adjusting step of heating the pre-oxidation gas that has passed through the heat exchanger, and adjusting the temperature of the exhaust gas so that the temperature of the exhaust gas after heating is within a predetermined temperature range;
An exhaust gas treatment method comprising:
The exhaust gas treatment method according to claim 14,
In the temperature adjusting step, the temperature of the gas before the exhaust gas from the gas generation source that has started to operate flows into the oxidation reactor, before flowing into the oxidation reactor, or out of the oxidation reactor is Adjusting the temperature of the gas to be within a predetermined temperature range;
Exhaust gas treatment method.
The exhaust gas treatment method according to claim 14 or 15,
Including a denitration step of reducing nitrogen oxide contained in the exhaust gas after being temperature-adjusted in the temperature-adjustment step and before being cooled in the heat exchange step by a denitration device;
In the denitration process, the oxidized gas after being processed in the oxidation process and before being cooled in the heat exchange process is processed,
In the temperature adjustment step, the temperature of the gas is adjusted so that the gas before flowing out from the oxidation reactor and flowing into the denitration apparatus falls within the predetermined temperature range.
Exhaust gas treatment method.
The exhaust gas treatment method according to claim 14 or 15,
Including a denitration step of reducing nitrogen oxide contained in the exhaust gas after being temperature-adjusted in the temperature-adjustment step and before being cooled in the heat exchange step by a denitration device;
In the denitration step, ammonia is injected as a nitrogen oxide reducing agent into the pre-oxidation gas after the temperature adjustment in the temperature adjustment step and before being processed in the oxidation reactor, and the nitrogen Reduce oxides,
Exhaust gas treatment method.
The exhaust gas treatment method according to claim 17,
In the temperature adjustment step, the temperature of the gas is adjusted so that the gas after the temperature adjustment in the temperature adjustment step and before flowing into the denitration apparatus falls within the predetermined temperature range.
Exhaust gas treatment method.
A denitration step of injecting ammonia into the exhaust gas as a nitrogen oxide reducing agent to reduce the nitrogen oxide;
An oxidation treatment step of oxidizing carbon monoxide contained in the exhaust gas treated in the denitration step with a catalyst in which Pt is supported on a titania carrier;
An exhaust gas treatment method comprising:
The exhaust gas treatment method according to any one of claims 16 to 18,
While the exhaust gas and the first refrigerant after being treated in the denitration step and the oxidation treatment step and before being cooled in the heat exchange step are heat-exchanged to cool the exhaust gas, Including a waste heat recovery process for heating one refrigerant,
Exhaust gas treatment method.
The exhaust gas treatment method according to claim 20,
In the exhaust heat recovery step, the heat exchange between the exhaust gas and the first refrigerant is limited according to the temperature of the exhaust gas before heat exchange in the exhaust heat recovery step.
Exhaust gas treatment method.
The exhaust gas treatment method according to any one of claims 14 to 18, 20, and 21.
Heat exchange between the exhaust gas and the second refrigerant after being cooled in the heat exchange step, and cooling the exhaust gas while heating the second refrigerant,
Exhaust gas treatment method.