JP2017124385A - Exhaust gas treatment device and exhaust gas treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas treatment technology that can efficiently perform exhaust heat recovery.SOLUTION: An exhaust gas treatment device includes: an exhaust gas route through which an exhaust gas passes; a waste heat recovery boiler 3 provided in the exhaust gas route to recover exhaust gas heat and generate vapor; and a denitration device 6 provided downstream relative to the waste heat recovery boiler 3 of the exhaust gas route to convert NOx contained in the exhaust gas after the waste heat recovery boiler 3 recovers heat, into nitrogen and water by ammonia catalytic reduction using an ammonia reduction agent and denitration catalyst.SELECTED DRAWING: Figure 1

Description

  Embodiments of the present invention relate to an exhaust gas treatment technique for a power plant in which combined cycle power generation is performed.

  In a thermal power plant where combined cycle power generation or the like is performed, a denitration device is disposed in a waste heat recovery boiler. The denitration apparatus is provided with a denitration catalyst and has a role of detoxifying nitrogen oxides contained in the exhaust gas to water and nitrogen.

  In recent years, supply of electric power from renewable energy such as solar power generation is supplied to an electric power network, which causes fluctuations in the supply and demand of electric power, and the adjustment of electric power supply and demand by adjusting the output of a thermal power plant may be performed. However, with the output adjustment (non-rated operation) of the thermal power plant according to the supply and demand fluctuation, the temperature of the exhaust gas becomes a low temperature at which the catalyst does not work easily. There is a catalyst that has improved the function at such a low temperature (see, for example, Patent Document 1).

  Moreover, in the operation outside the rating, there is a fear that the denitration by the current denitration apparatus is not sufficiently performed because the ratio of nitrogen dioxide in the nitrogen oxides increases at the same time as the temperature is lowered. Therefore, there is a catalyst that can cope with low-temperature exhaust gas even at a high nitrogen dioxide ratio (see, for example, Patent Document 2).

  For example, in the case of photovoltaic power generation, which is one of renewable energies, such off-rated driving opportunities increase in limited weather conditions where sunlight is frequently blocked, but there is no blocking. In the case, normal rated operation is the main. Therefore, it is necessary to achieve both denitration of exhaust gas at different temperatures and different nitrogen dioxide ratios depending on weather conditions.

JP 2002-36198 A JP 2008-119651 A

Basic Industrial Catalytic Reaction, Catalysis Society of Japan, p260

  When the denitration device is disposed in the waste heat recovery boiler, a part of the heat of the exhaust gas is consumed for the denitration reaction. Therefore, waste heat recovery cannot be performed efficiently in the waste heat recovery boiler.

  The embodiment of the present invention has been made in view of such circumstances, and an object thereof is to provide an exhaust gas treatment technique capable of efficiently performing waste heat recovery.

  An exhaust gas treatment apparatus according to an embodiment of the present invention includes an exhaust gas path through which exhaust gas passes, a waste heat recovery boiler that is provided in the exhaust gas path and recovers heat of the exhaust gas to generate steam, and the exhaust gas path Nitrogen oxides provided in the exhaust gas after the heat is recovered by the waste heat recovery boiler provided downstream from the waste heat recovery boiler are converted into nitrogen by ammonia catalytic reduction using an ammonia reducing agent and a denitration catalyst. And a denitration device that converts water into water.

  An exhaust gas treatment method according to an embodiment of the present invention includes a waste heat recovery step of recovering heat of exhaust gas passing through an exhaust gas path to generate steam, and the exhaust gas after heat is recovered by the waste heat recovery step. The exhaust gas treatment method includes a denitration step of converting contained nitrogen oxides into nitrogen and water by ammonia catalytic reduction using an ammonia reducing agent and a denitration catalyst.

  The embodiment of the present invention provides an exhaust gas treatment technology capable of efficiently performing waste heat recovery.

The figure which shows the structure of the thermal power plant to which the denitration apparatus of 1st Embodiment was applied. The figure which shows the denitration apparatus of 2nd Embodiment. The figure which shows the filter which the denitration apparatus of 2nd Embodiment has. The graph which shows the example of evaluation of the denitration performance of a denitration catalyst.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a configuration of a thermal power plant to which the denitration apparatus according to the first embodiment of the present invention is applied. In the thermal power plant of the present embodiment, a combined cycle power generation system is employed in which internal combustion power generation using a gas turbine is performed and steam power generation is performed with the exhaust heat.

  As shown in FIG. 1, the thermal power plant of this embodiment is provided with a gas turbine 1 as an internal combustion engine. The gas turbine 1 is rotated by combustion of fuel together with a compressor that compresses air, a combustion chamber that burns fuel, a fuel supply that supplies fuel to the combustion chamber, and air compressed by the compressor. And a turbine. And the rotational force of a turbine is transmitted to the 1st generator 10, and internal combustion power generation is performed. When the thermal power plant is performing the rated operation, the temperature of the exhaust gas is 300 ° C to 400 ° C. On the other hand, since the output of the gas turbine 1 is suppressed when the thermal power plant is operating outside the rating or when the thermal power plant is started up, the temperature of the exhaust gas becomes 250 ° C. or lower.

  The exhaust gas discharged from the gas turbine 1 is sent to the waste heat recovery boiler 3 through the first flue 2. The waste heat recovery boiler 3 has a water pipe 5 through which water is conducted. The water pipe 5 is a thin pipe bent at a plurality of positions inside the waste heat recovery boiler 3, and the surface area to which exhaust gas hits is increased by being bent. Steam is generated when water flowing through the water pipe 5 inside the waste heat recovery boiler 3 exchanges heat with the exhaust gas. This process is a waste heat recovery process in which the heat of exhaust gas is recovered to generate steam. As will be described later, the exhaust gas sent to the waste heat recovery boiler 3 enters the second flue 4. The exhaust gas is denitrated by the denitration catalyst 8 of the denitration device 6 provided in the second flue 4 and then discharged from the chimney 9 into the atmosphere.

  A water pipe 5 extending from the waste heat recovery boiler 3 is connected to the steam turbine 12. The steam generated inside the water pipe 5 by heat exchange with the exhaust gas is sent to the steam turbine 12. The steam turbine 12 is rotated by the pressure of the steam. And the rotational force of the steam turbine 12 is transmitted to the 2nd generator 11, and steam power generation is performed.

  Further, the steam turbine 12 is connected to a condenser 13. The steam that has rotated the steam turbine 12 is condensed by the condenser 13 and returned to water. Further, the water pipe 5 extending from the condenser 13 is connected to the waste heat recovery boiler 3. And the water of the condenser 13 is sent to the water pipe 5 inside the waste heat recovery boiler 3 again by a water supply pump (not shown).

  Thus, efficient power generation can be performed by reusing the heat of the exhaust gas discharged from the gas turbine 1 used for internal combustion power generation for steam power generation. In addition, the temperature of the exhaust gas after heat exchange is performed in the waste heat recovery boiler 3 is about 70 ° C. to 100 ° C. The exhaust gas after passing through the waste heat recovery boiler 3 is always at a temperature of 170 ° C. or lower, regardless of whether the thermal power plant is in a rated operation or an unrated operation (including during startup). Here, the temperature when the temperature of the exhaust gas is 170 ° C. or lower is assumed to be a low temperature.

  The exhaust gas subjected to heat exchange in the waste heat recovery boiler 3 is sent to the chimney 9 through the second flue 4. In the present embodiment, an exhaust gas path through which exhaust gas passes is formed by the first flue 2, the waste heat recovery boiler 3, and the second flue 4. Further, the second flue 4 is provided with a denitration device 6 that performs denitration to convert nitrogen oxides contained in the exhaust gas into nitrogen and water by ammonia catalytic reduction using an ammonia reducing agent and a denitration catalyst 8. ing.

  The denitration device 6 has a denitration catalyst 8 and an injector 7 as spraying means for spraying an ammonia reducing agent toward the denitration catalyst 8. The injector 7 is provided upstream of the denitration catalyst 8 in the exhaust gas path. The ammonia reducing agent sprayed from the injector 7 is sufficiently mixed with the exhaust gas before reaching the denitration catalyst 8. The injector 7 may be disposed at a predetermined distance from the denitration catalyst 8 or may be disposed immediately before the denitration catalyst 8. The exhaust gas mixed with the ammonia reducing agent reaches the denitration catalyst layer of the denitration catalyst 8 and is converted into nitrogen and water by the following reaction formulas (1) to (3). This process is a denitration process for denitrating exhaust gas.

_{4NO + 4NH 3 + O 2 →} 4N 2 + 6H 2 O ... Reaction Formula (1)
NO + NO ₂ + 2NH ₃ → 2N ₂ + 3H ₂ O ... Reaction formula (2)
6NO ₂ + 8NH ₃ → 7N ₂ + 12H ₂ O ... Reaction formula (3)

In the denitration reaction, the main reaction changes depending on the ratio of NO to NO ₂ in NOx. In the reaction formulas (1) and (2), the main reaction occurs when the NO ₂ ratio (NO ₂ / NOx ratio) in NOx is 0.5 or less, and a high denitration rate is easily obtained because the reaction rate is relatively fast. . On the other hand, the reaction formula (3) becomes a main reaction under high NO ₂ conditions in which the NO ₂ / NOx ratio is 0.6 or more.

  The denitration catalyst 8 of the present embodiment is a catalyst containing a metal composed of silver and ruthenium as a component with respect to an aluminum oxide carrier. The denitration catalyst 8 may contain silver metal oxide or ruthenium metal oxide as a component. By using such a denitration catalyst 8, denitration of low temperature exhaust gas at 170 ° C. or lower can be performed.

  The denitration device 6 is provided at a position immediately before the chimney 9 in the exhaust gas path. That is, the denitration device 6 performs denitration at a position immediately before the exhaust gas enters the chimney 9. In this way, the ammonia reducing agent is sprayed from the injector 7 at a position immediately before the exhaust gas enters the chimney 9 having the lowest temperature. Therefore, the oxidation reaction of the ammonia reducing agent can be suppressed, and the consumption amount of the ammonia reducing agent is reduced.

  The chimney 9 is a long cylindrical device for guiding the exhaust gas upward based on the principle of ascending current, and discharges the exhaust gas introduced from the lower part into the atmosphere through the upper opening. The denitration device 6 may be provided inside the chimney, or may be provided below the chimney. Further, the position immediately before the exhaust gas enters the chimney refers to a state in which there is no other device between the denitration device 6 and the chimney 9 and only the exhaust gas path, and between the denitration device 6 and the chimney 9. A certain distance may be provided. Further, since there is no other device in the exhaust gas path immediately before the chimney 9, this space is the place where the denitration device 6 is most easily provided. The exhaust gas denitrated by the denitration device 6 is released into the atmosphere via the chimney 9.

  Further, in the prior art, the waste heat recovery boiler 3 and the denitration device 6 have to be provided integrally because of the restriction of the temperature at which the denitration catalyst 8 functions. On the other hand, in this embodiment, the denitration device 6 can be made independent from the waste heat recovery boiler 3 and provided separately. Therefore, it becomes possible to improve the operability and maintainability of the waste heat recovery boiler 3 and the denitration device 6.

  In the present embodiment, the denitration device 6 is provided on the downstream side of the waste heat recovery boiler 3. Then, denitration for converting nitrogen oxides contained in the exhaust gas of 170 ° C. or lower after heat is recovered by the waste heat recovery boiler 3 into nitrogen and water by ammonia catalytic reduction using an ammonia reducing agent and a denitration catalyst. I do. Therefore, in the present embodiment, waste heat recovery can be performed using exhaust gas before heat is taken away by the ammonia catalytic reduction reaction for denitration, so that waste heat recovery can be performed efficiently. Further, since the exhaust gas after the waste heat recovery is always at a temperature of 170 ° C. or less, it is not necessary to frequently change the amount of the ammonia reducing agent input, so that stable denitration can be performed.

In the present embodiment, the denitration catalyst 8 is a catalyst having a metal or metal oxide composed of silver and ruthenium as a component with respect to an aluminum oxide carrier, and thus has high activity as a catalyst even at low temperatures. Therefore, the denitration of the low temperature exhaust gas at 170 ° C. or less at the standard pressure can be performed. The low temperature exhaust gas may be any temperature as long as it is 170 ° C. or lower. For example, the temperature may be 150 ° C. or lower, 130 ° C. or lower, 125 ° C. or lower, 110 ° C. or lower, 100 ° C. or lower, or 90 ° C. or lower. In addition, the conventional denitration catalyst has a problem that denitration of low-temperature exhaust gas at 170 ° C. or lower cannot be performed, but this embodiment can solve such a problem. In addition, the denitration catalyst 8 of the present embodiment can denitrate exhaust gas under a high NO ₂ condition that occurs due to a low temperature.

  Next, a denitration apparatus 6A according to the second embodiment will be described with reference to FIGS. In addition, about the same component as the component shown by embodiment mentioned above, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

As shown in FIG. 2, the denitration device 6 </ b> A is provided in the second flue 4 as in the above-described embodiment. The denitration apparatus 6A, the catalyst cartridge ₈₀ 1, ₈₀ 2 of a plurality (n sheets), having a denitration catalyst 8A consisting of ... 80 _n. Each of the catalyst cartridges 80 ₁ , 80 ₂ ,... 80 _n has the same configuration, and is formed as a plate-like member having a quadrangular shape. These catalyst cartridges 80 ₁ , 80 ₂ ,... 80 _n are provided so as to be orthogonal to the flow direction of the exhaust gas in the second flue 4, and the exhaust gas enters from one surface and is discharged from the other surface. It has come to be. The second flue 4 has a square tube shape that is a quadrangular shape in a sectional view, and the catalyst cartridges 80 ₁ , 80 ₂ ,... 80 _n are detachable so as to partition the inside of the second flue 4. Is attached.

In addition, the catalyst cartridges 80 ₁ , 80 ₂ ,... 80 _n are arranged side by side along the exhaust gas passage direction inside the second flue 4 with the surfaces on the side where the exhaust gas enters facing in the same direction. Yes. For example, the exhaust gas that has passed through the first catalyst cartridge 80 ₁ is adapted to pass through the other catalyst cartridge 80 _2.

In addition to nitrogen oxides, the exhaust gas contains an inhibitory component that inhibits denitration such as a small amount of dust and vapor (humidity). Therefore catalyst cartridge ₈₀ 1 as the use period becomes longer, ₈₀ 2, ... 80 _n denitration performance is lowered. For example, the first sheet of the catalyst cartridge 80 ₁ is disposed on the upstream side with respect to the passing direction of the exhaust gas is susceptible to inhibitory components contained in the exhaust gas,耐使for periods shorter, the replacement frequency is increased.

The catalyst cartridge ₈₀ 1, ₈₀ 2, when ... 80 _n is exhausted, a new catalyst cartridge ₈₀ 1, ₈₀ 2, can be exchanged for ... 80 _n. Although not particularly illustrated, a maintenance port that is opened and closed in the second flue 4 may be provided, and the replacement operation of the catalyst cartridges 80 ₁ , 80 ₂ ,... 80 _n may be performed through the maintenance port. A maintenance port is provided at a side position of the second flue 4 so that the replacement operation of the catalyst cartridges 80 ₁ , 80 ₂ ,... 80 _n is performed from the side of the second flue 4.

The catalyst cartridge ₈₀ 1, ₈₀ 2 denitration catalyst 8A is a plurality of the second embodiment, since a ... 80 _n, the catalyst cartridge ₈₀ 1, ₈₀ 2 individually according to the exhaustion degree, can exchange ... 80 _n. Further, the replacement work can be easily performed. Also, the catalyst cartridge 80 ₁ the exhaust gas hits the first consumable becomes vigorous, so the exhaust gas catalyst cartridge 80 _n is hardly wasting hits the end, the catalyst cartridge 80 _1, 80 2, _... in the 80 _n at the exchange, severe wasting replace the catalyst cartridge 80 _1, because most catalytic cartridge 80 _n that are not exhausted can continue to use consumption can be reduced the amount of denitration catalyst 8A.

Further, the arrangement of the catalyst cartridges 80 ₁ , 80 ₂ ,... 80 _n may be periodically changed. For example, by replacing the first sheet of the catalyst cartridge 80 ₁ on the downstream side of the catalyst cartridge 80 _n of the n-th, it may be a second sheet of the catalyst cartridge 80 ₂ the first as the exhaust gas hits, periodically this by repeating the catalyst cartridge ₈₀ 1, ₈₀ 2 may extend the life of ... 80 _n.

  When the exhaust gas is at a low temperature, moisture contained in the exhaust gas is likely to be condensed. In the second embodiment, a metal filter 20 (demister) is provided upstream of the denitration catalyst 8A in order to remove moisture (humidity) contained in the exhaust gas. In this example, a metal filter 20 is provided between the injector 7 and the denitration catalyst 8A. Note that the metal filter 20 may be provided on the upstream side of the injector 7.

  The metal filter 20 includes an outer frame 23 attached along the inner periphery of the second flue 4 and an aggregate of metal fibers such as a wire mesh 24 held by the outer frame 23. The wire mesh 24 has a fibrous shape to increase the contact area with the exhaust gas (fluid). The outer frame 23 is provided in order to maintain the shape of the wire mesh 24 with respect to the flow of exhaust gas.

  The second flue 4 is partitioned by the metal filter 20 (wire mesh 24). The exhaust gas that passes through the second flue 4 always passes through the metal filter 20 and then hits the denitration catalyst 8A. In addition, since exhaust gas contains an acidic component, it is desirable to form the metal filter 20 with a material excellent in corrosion resistance, for example, a material such as SUS317.

  The exhaust gas that has entered the second flue 4 passes through the metal filter 20 after being mixed with the ammonia reducing agent sprayed from the injector 7. The exhaust gas may pass through the metal filter 20 before being mixed with the ammonia reducing agent. Then, the exhaust gas is dehumidified or dedusted by the metal filter 20.

  Further, the metal filter 20 has a metal pipe 25 provided along with the wire mesh 24 inside the outer frame 23. The metal pipe 25 is a thin pipe bent at a plurality of locations, and a cooling medium is conducted through the pipe. Note that the cooling medium may be cooling water, a cooling gas, or the like. The wire mesh 24 is cooled by the cooling medium, the vapor contained in the exhaust gas is condensed, and flows down through the wire mesh 24 as water. Furthermore, a storage tank 21 for accumulating condensed water is provided below the metal filter 20. Furthermore, a drainage drain 22 is also provided for draining water accumulated in the storage tank 21. When the storage tank 21 is full, drainage is appropriately performed from the drainage drain 22.

  In the second embodiment, moisture contained in the exhaust gas is condensed by the cooled metal filter 20 and can be drained smoothly (continuously) by the drainage drain 22, thus preventing moisture from hitting the denitration catalyst 8A. Can do.

  In the second embodiment, moisture (humidity) can be removed by the metal filter 20, so that the denitration catalyst 8A can be protected. Moreover, since the metal filter 20 shakes the fibrous wire mesh 24, a contact area with exhaust gas can be increased and moisture can be efficiently removed. Further, since the wire mesh 24 is cooled by the metal pipe 25 through which the cooling medium is conducted, the condensability of moisture contained in the exhaust gas can be enhanced. Moreover, it is possible to prevent water from being moved to the other inside the second flue 4 by storing the dropped water flowing from the metal filter 20 in the storage tank 21.

Next, an evaluation example of the denitration performance of the denitration catalyst used in this embodiment will be described with reference to the graph shown in FIG. The denitration catalyst of this embodiment is a catalyst of aluminum oxide (alumina) containing silver (Ag) and ruthenium (Ru). The evaluation of the denitration performance is performed in an environment around 100 ° C. that simulates the temperature inside the second flue 4 described above. In this example, the temperature is 97 ° C. and 125 ° C. As the reaction gas, simulating the composition of high NO ₂ ratio exhaust gas, 180ppmNOx _(NO 2 / NOx ratio _{0.76) + 234ppmNH 3 (NH 3} / NOx ratio 1.3) + simulated post-combustion air (16% O ₂ + 84% N ₂ ) was set.

The configuration of the denitration evaluation apparatus includes a reaction gas preparation unit that generates a reaction gas using gas cylinders of NO / N ₂ , NO ₂ / N ₂ , NH ₃ / N ₂ , O _2, and N ₂ , and a predetermined reaction gas. A reaction gas heating unit that heats the catalyst sample, a catalyst layer into which the catalyst sample is introduced, and a gas analysis unit that analyzes the NO, NO ₂ , and NH ₃ concentrations after passing through the catalyst layer.

The reaction gas is measured so that the flow rate becomes 3 L / min with a mass flow controller by measuring the flow rate using a float type flow meter. The catalyst amount was 10 g, and the space flow rate was about 15000 h ⁻¹ . A thermometer is installed on the downstream side of the reaction gas heating unit and the catalyst layer to confirm that the temperature reaches a predetermined temperature. Further, the analysis unit collects the exhaust gas for analysis. This analysis was performed using a gas detector manufactured by GASTEC for NO and NO ₂ separation measurement. In addition, the content of the component contained in the denitration catalyst carrier is desirably about 0.5 to 5%.

NO / N ₂ , NO ₂ / N ₂ , NH ₃ / N ₂ , O ₂ and N ₂ gas supplied from each gas cylinder are mixed by a static mixer and heated to the reaction temperature. The heated exhaust gas reaches the catalyst layer, and the reactions of the above-described reaction formulas (1) to (3) proceed. The exhaust gas that has passed through the catalyst layer is exhausted after the exhaust gas treatment through the analysis unit.

FIG. 4 is a graph showing the results of NH ₃ concentration, NOx concentration, NO concentration, NO ₂ concentration, and denitration rate contained in the reaction gas after denitration at reaction temperatures of 97 ° C. and 125 ° C. At 97 ° C., the NOx concentration after passing through the catalyst layer is 15 ppm (14 ppm NO + 1 ppm NO ₂ ), and the denitration rate is 91.67%. At 125 ° C., the NOx concentration after passing through the catalyst layer is 12 ppm (9 ppm NO + 3 ppm NO ₂ ) and the denitration rate is 93.56%. From this result, it can be confirmed that the denitration function works effectively even in a temperature range of around 100 ° C.

  In this embodiment, an aluminum oxide (alumina) catalyst containing silver (Ag) and ruthenium (Ru) is used as a denitration catalyst. However, the denitration catalyst is not limited to this configuration and includes other components. May be. For example, for at least one support of cerium oxide, titanium oxide, and magnesium oxide, at least one metal or metal oxide of copper, nickel, palladium, cobalt, rhodium, and iron was included. It may be a catalyst. Since these substances are thermally stable and have a high activity at low temperatures, it is possible to perform denitration of low-temperature exhaust gas.

  According to the exhaust gas treatment apparatus of the embodiment described above, the denitration apparatus is provided on the downstream side of the waste heat recovery boiler. Then, denitration for converting nitrogen oxides contained in the exhaust gas at 170 ° C. or lower after heat is recovered by the waste heat recovery boiler into nitrogen and water by ammonia catalytic reduction using an ammonia reducing agent and a denitration catalyst. I do. Therefore, in the present embodiment, waste heat recovery can be performed using exhaust gas before heat is taken away by the ammonia catalytic reduction reaction for denitration, so that waste heat recovery can be performed efficiently.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Gas turbine, 2 ... 1st flue, 3 ... Waste heat recovery boiler, 4 ... 2nd flue, 5 ... Water pipe, 6, 6A ... Denitration device, 7 ... Injector, 8, 8A ... Denitration catalyst, 9 ... Chimney, 10 ... Generator, 11 ... Generator, 12 ... Steam turbine, 13 ... Condenser, 20 ... Metal filter, 21 ... Storage tank, 22 ... Drain drain, 23 ... Outer frame, 24 ... Wire mesh, 25 ... Metal piping, 80 ... catalyst cartridge.

Claims (9)

An exhaust gas path through which the exhaust gas passes;
A waste heat recovery boiler which is provided in the exhaust gas path and recovers heat of the exhaust gas to generate steam;
Ammonia that is provided downstream of the waste heat recovery boiler in the exhaust gas path and uses nitrogen oxides contained in the exhaust gas after heat is recovered by the waste heat recovery boiler, using an ammonia reducing agent and a denitration catalyst A denitration device that converts nitrogen and water by catalytic reduction;
An exhaust gas treatment apparatus comprising:   The exhaust gas treatment apparatus according to claim 1, wherein the exhaust gas after heat is recovered by the waste heat recovery boiler is 170 ° C or lower.   3. The exhaust gas treatment apparatus according to claim 1, wherein the denitration catalyst is a catalyst containing a metal or metal oxide composed of silver and ruthenium as a component with respect to an aluminum oxide carrier. Connected to the exhaust gas path downstream from the waste heat recovery boiler, comprising a chimney in which the exhaust gas is discharged to the atmosphere,
The exhaust gas treatment apparatus according to any one of claims 1 to 3, wherein the denitration apparatus is provided at a position immediately before the exhaust gas enters the chimney.   The exhaust gas treatment device according to any one of claims 1 to 4, wherein the denitration device includes a filter provided on an upstream side of the denitration catalyst to remove moisture contained in the exhaust gas.   The exhaust gas treatment apparatus according to claim 5, wherein the filter condenses moisture contained in the exhaust gas when cooled, and the denitration device has a drainage drain capable of draining the condensed moisture.   The denitration catalyst has a plurality of plate-shaped catalyst cartridges, and each of the catalyst cartridges is orthogonal to the direction of the exhaust gas flowing in the exhaust gas path, and the exhaust gas that has passed through the catalyst cartridge is another The exhaust gas treatment apparatus according to any one of claims 1 to 6, wherein the catalyst cartridges are arranged side by side along a direction in which the exhaust gas passes so as to pass through the cartridge.   The exhaust gas is discharged from a gas turbine used for internal combustion power generation, and the steam generated by the waste heat recovery boiler rotates the steam turbine to perform steam power generation. The exhaust gas treatment apparatus according to claim 1. A waste heat recovery process for recovering heat of exhaust gas passing through the exhaust gas path to generate steam;
A denitration step of converting nitrogen oxides contained in the exhaust gas after heat is recovered by the waste heat recovery step into nitrogen and water by ammonia catalytic reduction using an ammonia reducing agent and a denitration catalyst;
An exhaust gas treatment method comprising:

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