JP2024067774A - Denitrification control device and denitrification device - Google Patents

Abstract

[Problem] Ammonia flowing out downstream of a denitration device is suppressed. [Solution] A denitration control device according to at least one embodiment of the present disclosure is a control device for a denitration device equipped with a denitration reactor for removing nitrogen oxides from exhaust gas discharged from a combustion device that uses ammonia as fuel. The denitration control device according to at least one embodiment of the present disclosure includes an input amount calculation unit that calculates an input amount of reducing agent based on an excess amount of reducing agent that takes into account unburned ammonia. [Selected Figure] FIG.

Description

This disclosure relates to a denitration control device and a denitration device.

2. Description of the Related Art There is known a denitration device that removes or reduces nitrogen oxides (NO _x ) contained in exhaust gas from a combustion device by reacting the nitrogen oxides with a reducing agent to decompose the nitrogen oxides into harmless nitrogen and water (see, for example, Patent Document 1).

Patent Document 1 discloses a denitration system including an ammonia injection device that injects ammonia as a reducing agent into exhaust gas from a boiler, a denitration catalyst provided downstream of the ammonia injection device in the exhaust gas flow passage, and an adjustment means for adjusting the amount of ammonia injected from the ammonia injection device. The adjustment means is configured to adjust the amount of reducing agent supplied based on the _NOx concentration distribution in the exhaust gas flow passage cross section at the outlet side of the denitration catalyst so that more ammonia is supplied to an area where denitration is insufficient (i.e., an area where the _NOx concentration is relatively high).

JP 2014-100630 A

In such denitration equipment, if an excessive amount of reducing agent is supplied, there is a risk that ammonia will leak downstream of the denitration equipment. If ammonia leaks downstream of the denitration equipment, there is a risk of blockage or corrosion due to the generation of acidic ammonium sulfate. Therefore, it is necessary to suppress the ammonia leaking downstream of the denitration equipment as much as possible.

In view of the above circumstances, at least one embodiment of the present disclosure aims to suppress ammonia flowing downstream of the denitrification device.

(1) A denitration control device according to at least one embodiment of the present disclosure includes:
A control device for a denitration device having a denitration reactor for removing nitrogen oxides from exhaust gas discharged from a combustion device using ammonia as fuel,
an input amount calculation unit that calculates an input amount of the reducing agent based on an excess amount of the reducing agent taking into account unburned ammonia;
Equipped with.

(2) A denitration device according to at least one embodiment of the present disclosure,
A denitration control device having the configuration of (1) above;
The denitrification reactor;
A reducing agent input unit for inputting the reducing agent into the exhaust gas;
Equipped with.

According to at least one embodiment of the present disclosure, ammonia flowing downstream of the denitrification device can be suppressed.

1 is a schematic configuration diagram showing a boiler system including a boiler using ammonia fuel and a fuel other than ammonia fuel as main fuel according to an embodiment of the present invention as an example of a combustion device. FIG. 2 is a schematic diagram for explaining a plurality of sections obtained by dividing a cross section of a denitration reactor perpendicular to the flow of exhaust gas. FIG. 2 is a block diagram of control of the supply amount of reducing agent by the denitration control device according to the first embodiment. FIG. 2 is a diagram showing a schematic arrangement of sensors in the denitration control device according to the first embodiment, for one section. FIG. FIG. 11 is a block diagram of a control of the supply amount of a reducing agent by a denitration control device according to a second embodiment. FIG. 11 is a block diagram showing control of the supply amount of reducing agent by a denitration control device according to a third embodiment. FIG. 13 is a diagram showing a schematic arrangement of sensors in a denitration control device according to a second embodiment and a third embodiment, the diagram showing one section. FIG. 13 is a block diagram showing control of the supply amount of reducing agent by a denitration control device according to a fourth embodiment. FIG. 13 is a diagram showing a schematic arrangement of sensors in a denitration control device according to a fourth embodiment, for one section. FIG. 1 is a block diagram for estimating the inlet NH ₃ concentration (unburned ammonia concentration) using a prediction model for the inlet NH ₃ concentration. FIG. 1 is a block diagram for estimating inlet _NOx concentration using a predictive model of inlet _NOx concentration.

Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure.
For example, expressions expressing relative or absolute configuration, such as "in a certain direction,""along a certain direction,""parallel,""orthogonal,""center,""concentric," or "coaxial," not only express such a configuration strictly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained.
For example, expressions indicating that things are in an equal state, such as "identical,""equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained.
For example, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to rectangular shapes, cylindrical shapes, etc. in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained.
On the other hand, the expressions "comprise,""include,""have,""includes," or "have" of one element are not exclusive expressions excluding the presence of other elements.

<1. Overall configuration of boiler system 1>
FIG. 1 is a schematic diagram showing a boiler system 1 according to the present embodiment as an example of a combustion device, the boiler system 1 including a boiler using ammonia fuel and a fuel other than ammonia fuel as main fuels.

The boiler 10 included in the boiler system 1 of this embodiment is a boiler that can burn ammonia fuel and other fuels other than ammonia fuel using a burner and generate superheated steam by exchanging the heat generated by this combustion with feed water or steam. As the other fuel, for example, a solid fuel such as biomass fuel or coal is used. The solid fuel is, for example, pulverized coal fuel made by finely pulverizing coal. In addition, the ammonia fuel is a liquid or gas containing ammonia.

The boiler 10 has a furnace 11, combustion devices 20, 50, and a combustion gas passage 12. The furnace 11 has a hollow rectangular cylinder shape and is installed vertically. The furnace wall 101 that constitutes the inner wall surface of the furnace 11 is composed of multiple heat transfer tubes and fins that connect the heat transfer tubes to each other, and recovers the heat generated by the combustion of fuel by heat exchange with water and steam flowing inside the heat transfer tubes, while suppressing the temperature rise of the furnace wall 101.

The combustion devices 20 and 50 are installed in the lower region of the furnace 11. In this embodiment, the combustion device 20 is configured to inject pulverized coal fuel into the interior of the furnace 11. Also, the combustion device 50 is configured to inject ammonia fuel into the interior of the furnace 11.

The combustion device 20 has a plurality of burners 21 attached to the furnace wall 101, and the combustion device 50 has a plurality of ammonia burners (ammonia combustion burners) 51. An injection nozzle (not shown) configured to inject pulverized coal fuel into the furnace 11 is provided at the tip of each burner 21. In addition, each ammonia burner 51 is provided with an ammonia injection nozzle (not shown).

The burners 21 and ammonia burners 51 are arranged at equal intervals along the circumferential direction of the furnace 11 (for example, four burners installed at each corner of the rectangular furnace 11), and are arranged in multiple stages along the vertical direction. In the example of FIG. 1, one set of burners 21 is arranged in two stages, and one set of ammonia burners 51 is arranged in four stages. Note that, for convenience of illustration, FIG. 1 shows only two burners of one set, and each set is given the reference numerals 21 and 51. The shape of the furnace, the number of burner stages, the number of burners in one stage, the arrangement of the burners, and the like are not limited to this embodiment.
In addition, the combustion method in the furnace 11 of this embodiment is a swirling combustion method in which burners are installed at the corners and a flame that swirls in a spiral shape is formed inside the furnace 11, but other combustion methods may be used. Depending on the combustion method to be adopted, the shape of the furnace 11 and the arrangement of the multiple burners 21 and the multiple ammonia burners 51 may be appropriately changed. As another combustion method, for example, there is an opposed combustion method in which burners are installed on both of a pair of opposing furnace walls of the furnace 11.

The burners 21 of the combustion device 20 are connected to a plurality of mills (pulverizers) 31A, 31B (hereinafter, collectively referred to as "mills 31") via a plurality of pulverized coal fuel supply pipes 22A, 22B (hereinafter, collectively referred to as "pulverized coal fuel supply pipes 22"). The mill 31 is, for example, a vertical roller mill in which a grinding table (not shown) is supported inside so that it can be driven and rotated, and a plurality of grinding rollers (not shown) are supported above the grinding table so that they can rotate in conjunction with the rotation of the grinding table. The solid fuel pulverized by the cooperation of the grinding rollers and the grinding table is transported to a classifier (not shown) provided in the mill 31 by primary air (transport gas, oxidizing gas) supplied to the mill 31. In the classifier, the fuel is classified into pulverized coal fuel having a particle size smaller than that suitable for combustion in the burner 21 and coarse pulverized coal fuel having a particle size larger than that particle size. The pulverized coal fuel passes through the classifier and is supplied to the burner 21 together with the primary air through the pulverized coal fuel supply pipe 22. The coarse pulverized coal fuel that does not pass through the classifier falls onto the grinding table by its own weight inside the mill 31 and is re-pulverized.

The above-mentioned primary air (conveying gas, oxidizing gas) supplied to the mill 31 is sent to the mill 31 from a primary air fan 33 (PAF: Primary Air Fan) that takes in outside air via an air pipe 30. The air pipe 30 is equipped with a hot air induction pipe 30A through which hot air heated by an air heater (air preheater) 42 flows from the air sent out from the primary air fan 33, a cold air induction pipe 30B through which cold air close to room temperature that does not pass through the air heater 42 flows from the air sent out from the primary air fan 33, and a conveying gas flow path 30C through which the hot air and cold air join and flow.

The ammonia burner 51 of the combustion device 50 is connected to the ammonia fuel supply unit 90. The ammonia fuel supply unit 90 of this embodiment includes an ammonia tank 91 and an ammonia fuel supply pipe 92 for supplying ammonia fuel (e.g., liquid ammonia) stored in the ammonia tank 91 to the combustion device 50 of the boiler 10. When the ammonia gas injection method is adopted, a vaporizer (not shown) for subjecting liquid ammonia to a vaporization process may be provided in the ammonia fuel supply unit 90. When the liquid ammonia injection method is adopted, the ammonia fuel supply unit 90 may further include an atomization fluid supply pipe (not shown) for supplying an atomization fluid for atomizing liquid ammonia to the combustion device 50.

An air register (wind box) 23 is provided on the outside of the furnace 11 at the installation position of the burner 21 and the ammonia burner 51, and one end of an air duct (air duct) 24 is connected to the air register 23. A forced draft fan (FDF: Forced Draft Fan) 32 is connected to the other end of the air duct 24. The air supplied from the forced draft fan 32 is heated by an air preheater 42 installed in the air duct 24, and is supplied to the burner 21 via the air register 23 as secondary air (combustion air, oxidizing gas), and is supplied to the ammonia burner 51 as combustion air (oxidizing gas), and is then introduced into the furnace 11.

The combustion gas passage 12 is connected to the vertical upper part of the furnace 11. The combustion gas passage 12 is provided with superheaters 102A, 102B, and 102C (hereinafter, sometimes collectively referred to as "superheaters 102"), reheaters 103A and 103B (hereinafter, sometimes collectively referred to as "reheaters 103"), and a coal economizer 104 as heat exchangers for recovering heat from the combustion gas, and heat is exchanged between the combustion gas generated in the furnace 11 and the feed water or steam flowing inside each heat exchanger. The arrangement and shape of each heat exchanger are not limited to the form shown in FIG. 1.

The flue 13 is connected to the downstream side of the combustion gas passage 12, and discharges the combustion gas whose heat has been recovered by the heat exchanger. An air preheater (air heater) 42 is provided between the flue 13 and the wind duct 24, and heat is exchanged between the air flowing through the wind duct 24 and the combustion gas flowing through the flue 13. By heating the primary air supplied to the mill 31 and the combustion air supplied to the burner 21 and the ammonia burner 51, further heat is recovered from the combustion gas after heat exchange with water and steam.

The boiler system 1 of the present embodiment includes a denitration device 70. The denitration device 70 includes a denitration reactor 71, a reducing agent feed section 73, and a denitration control device 77.
The denitration reactor 71 is provided in the flue 13 at a position upstream of the air preheater 42. The denitration reactor 71 supplies a reducing agent having the effect of reducing nitrogen oxides, such as ammonia or urea water, to the combustion gas (exhaust gas) flowing through the flue 13, and promotes a reaction between the reducing agent and nitrogen oxides (NO _x ) in the exhaust gas to which the reducing agent has been supplied, by the catalytic action of a denitration catalyst provided in the denitration reactor 71, thereby removing and reducing the nitrogen oxides in the exhaust gas.

The reducing agent injection section 73 is equipped with an injection nozzle 74 for injecting the reducing agent into the flue 13 at a position upstream of the denitrification reactor 71, and a flow control valve 75 for adjusting the amount of reducing agent injected from the injection nozzle 74.
A plurality of input nozzles 74 and flow rate adjustment valves 75 are provided as described below.

The denitration control device 77 is a control device for adjusting the flow rate of the reducing agent flowing through each flow rate control valve 75 by controlling the opening degree of each flow rate control valve 75, thereby controlling the amount of reducing agent introduced into the flue 13. The denitration control device 77 includes a computer equipped with, for example, a processor (CPU, etc.), a storage device (memory device; RAM, etc.), an auxiliary storage unit, an interface, etc.
The control of the amount of reducing agent injected into the flue 13 by the denitration control device 77 will be described later.

A gas duct 41 is connected downstream of the air preheater 42 of the flue 13. The gas duct 41 is provided with environmental equipment such as a dust collector 44 such as an electrostatic precipitator that removes ash and the like from the exhaust gas, a desulfurization device 46 that removes sulfur oxides, and an induced draft fan (IDF) 45 that guides the exhaust gas to these environmental equipment. The downstream end of the gas duct 41 is connected to a chimney 47, and the exhaust gas treated by the environmental equipment is discharged outside the system.

In the boiler 10, when the multiple mills 31 are driven, pulverized and classified pulverized coal fuel is supplied together with primary air to the burner 21 via the pulverized coal fuel supply pipe 22. In addition, ammonia fuel is supplied from the ammonia fuel supply unit 90 to the ammonia burner 51. Furthermore, secondary air heated by the air preheater 42 is supplied from the air duct 24 to the burner 21 and the ammonia burner 51 via the air register 23.
The burner 21 injects a pulverized coal fuel mixture, which is a mixture of pulverized coal fuel and primary air, into the furnace 11, and also injects secondary air into the furnace 11. The pulverized coal fuel mixture injected into the furnace 11 is ignited and reacts with the secondary air to form a flame. The ammonia burner 51 injects combustion air together with ammonia fuel into the furnace 11. The ammonia fuel injected into the furnace 11 reacts with the combustion air and burns.
High-temperature combustion gas generated by the combustion of pulverized coal fuel and ammonia fuel rises within the furnace 11 and flows into the combustion gas passage 12 .
The timing at which the ammonia fuel is injected into the furnace 11 may be after the temperature inside the furnace 11 has risen to a certain temperature by the combustion of the pulverized coal fuel. For example, after the mono-combustion of the pulverized coal fuel is performed at the start of the boiler 10, the ammonia fuel may be injected into the furnace 11, and ammonia mixed combustion of the ammonia fuel and the pulverized coal fuel may be performed. Further thereafter, the injection of the pulverized coal fuel may be stopped, and the mono-combustion of ammonia may be performed.
In addition, in this embodiment, air is used as the oxidizing gas (primary air, secondary air, combustion air), but the oxidizing gas may have a higher or lower oxygen content than air, and stable combustion in the furnace 11 can be achieved by adjusting the ratio of the amount of oxygen to the amount of fuel supplied within an appropriate range.

The combustion gas that flows into the combustion gas passage 12 exchanges heat with water and steam in the superheater 102, reheater 103, and economizer 104 arranged inside the combustion gas passage 12, and is then discharged into the flue 13, where nitrogen oxides are removed in the denitration device 70, and the gas exchanges heat with primary air, secondary air, and combustion air in the air preheater 42, where nitrogen oxides are removed in the denitration reactor 71, and the gas is discharged into the gas duct 41, where ash and other particles are removed in the dust collector 44, and sulfur oxides are removed in the desulfurization device 46, and the gas is discharged from the chimney 47 to the outside of the system. Note that the arrangement of each heat exchanger in the combustion gas passage 12 and each device from the flue 13 to the gas duct 41 does not necessarily have to be in the order described above with respect to the flow of the combustion gas (exhaust gas).

The boiler of the present disclosure is not limited to the above-described embodiment. As the solid fuel used in the boiler, biomass fuel, petroleum coke (PC) fuel, petroleum residue, etc. may be used instead of or together with coal.
In addition, the fuel for the boiler to be combined with ammonia fuel is not limited to solid fuels, and can also be liquid fuels such as petroleum such as heavy oil, light oil, and heavy oil, and industrial waste liquid. In addition, gaseous fuels such as natural gas, various petroleum gases, and by-product gases generated in the steelmaking process can also be used.
Furthermore, the present invention can be applied to a multi-fuel boiler that uses a combination of these various fuels.

As described above, the boiler 10 according to at least one embodiment of the present disclosure includes the furnace 11 including the furnace wall 101, the ammonia burner 51 provided in the furnace wall 101, and the burner 21 provided at a position different from the ammonia burner 51 on the furnace wall 101 and serving as a pulverized coal burner for burning pulverized coal.
This makes it possible to suppress the amount of _NOx emitted from the boiler 10 according to at least one embodiment of the present disclosure.
The burner 21 may be a fuel burner that burns a fuel other than ammonia fuel.
Furthermore, the boiler 10 according to at least one embodiment of the present disclosure may be a multi-fuel boiler that burns ammonia fuel and a fuel other than ammonia fuel, or may be an ammonia-only boiler that burns only ammonia fuel. Note that when ammonia fuel and a fuel other than ammonia fuel are burned, the fuel may be a single type, or multiple types.

<Regarding the injection nozzle 74 and the flow rate control valve 75 of the denitrification device 70>
FIG. 2 is a schematic diagram for explaining a plurality of sections obtained by dividing a cross section of the denitration reactor 71 perpendicular to the flow of the exhaust gas.
In the boiler system 1 of the present embodiment, a cross section of the denitration reactor 71 perpendicular to the flow of the exhaust gas is virtually divided into a lattice shape to define a plurality of sections 81. In the example shown in Fig. 2, the section is divided into a total of 24 sections 81 of, for example, 3 rows and 8 columns, but the number of divisions is not limited to the example shown in Fig. 2.
In the boiler system 1 of the present embodiment, in order to make it possible to adjust the amount of reducing agent introduced into each of the sections 81, a plurality of introduction nozzles 74 are provided corresponding to each of the sections 81. In addition, a plurality of flow rate adjustment valves 75 are provided corresponding to each of the plurality of introduction nozzles 74.

<About excessive addition of reducing agent>
If the amount of reducing agent charged is too small, the concentration of _NOx in the exhaust gas discharged from the denitration reactor 71 increases. Conversely, if the amount of reducing agent charged is too large, unreacted ammonia is discharged from the denitration reactor 71. If ammonia flows out downstream of the denitration reactor 71, there is a risk of blockage, corrosion, etc. due to the generation of acid ammonium sulfate. Therefore, it is necessary to suppress the ammonia flowing out downstream of the denitration reactor 71 as much as possible.
The ammonia flowing out downstream of the denitration reactor 71 includes ammonia derived from the introduced reducing agent, and also includes ammonia derived from leak ammonia (unburned ammonia) contained in the exhaust gas when ammonia is used as fuel as in the boiler 10 of the present embodiment.
If the reducing agent is added without taking this leaked ammonia (unburned ammonia) into consideration, the leaked ammonia (unburned ammonia) will also be used for denitration in the denitration reactor, and there is a risk that the added reducing agent will be excessive, causing ammonia to flow out downstream of the denitration reactor 71.
Therefore, in the denitration control device 77 of the present embodiment, the supply amount of the reducing agent is set taking into consideration the leak ammonia (unburned ammonia) contained in the exhaust gas. Hereinafter, the control of the supply amount of the reducing agent in the denitration control device 77 of the present embodiment will be described.

<Control of the amount of reducing agent added>
FIG. 3 is a block diagram of the control of the supply amount of the reducing agent by the denitration control device 77 according to the first embodiment.
FIG. 4 is a diagram showing a schematic arrangement of sensors in the denitration control device 77 according to the first embodiment, and shows the arrangement for one section 81. As shown in FIG.
FIG. 5 is a block diagram of control of the supply amount of reducing agent by the denitration control device 77 according to the second embodiment.
FIG. 6 is a block diagram of control of the supply amount of reducing agent by a denitration control device 77 according to the third embodiment.
FIG. 7 is a diagram showing a schematic arrangement of sensors in a denitration control device 77 according to the second and third embodiments, and shows the arrangement for one section 81. As shown in FIG.
FIG. 8 is a block diagram of control of the supply amount of reducing agent by a denitration control device 77 according to the fourth embodiment.
FIG. 9 is a diagram showing a schematic arrangement of sensors in a denitration control device 77 according to the fourth embodiment, and shows the arrangement for one section 81. As shown in FIG.

<Configuration common to the denitration control device 77 according to the first to fourth embodiments>
As shown in Figures 3, 5, 6, and 8, the denitration control device 77 according to some embodiments includes, as functional blocks realized by execution of a program by a processor (not shown), an input amount calculation unit 771, a leak ammonia (unburned ammonia) flow rate acquisition unit 772, and a mass balance calculation unit 773.
The input amount calculation unit 771 is configured to calculate the input amount of the reducing agent based on the excess amount of the reducing agent taking into account leak ammonia (unburned ammonia).
The leak ammonia (unburned ammonia) flow rate acquisition unit 772 is configured to acquire the flow rate of unburned ammonia flowing into the denitration reactor 71 .
The mass balance calculation unit 773 is configured to calculate the amount of reducing agent to be input, which is determined from the mass balance, based on the target values of _{the NOx} concentration of the exhaust gas flowing into the denitration reactor 71, the flow rate of the exhaust gas flowing into the denitration reactor 71, and the NOx concentration of the exhaust gas discharged from the denitration reactor 71.

As shown in FIGS. 4, 7, and 9, a denitration control device 77 according to some embodiments includes an inlet _NOx concentration sensor 781 and an outlet _NOx concentration sensor 782.
The inlet _NOx concentration sensor 781 is a NOx concentration sensor for detecting the _NOx concentration of the exhaust gas flowing into the denitration reactor 71 upstream of the denitration reactor 71, and multiple sensors are provided to detect _{the NOx} concentration in the areas corresponding to each of the above-mentioned sections 81.
In addition, the same number of inlet _NOx concentration sensors 781 as the number of each of the above-mentioned compartments 81 may be provided, or a smaller number of inlet _NOx concentration sensors 781 than the number of each of the above-mentioned compartments 81 may be used, and the sampling flow path of the exhaust gas from the area corresponding to each compartment 81 may be appropriately switched so that the _NOx concentration of all of the areas corresponding to each of the above-mentioned compartments 81 can be detected.

The outlet _NOx concentration sensor 782 is a NOx concentration sensor for detecting the _NOx concentration of the exhaust gas flowing out from the denitration reactor 71 downstream of the denitration reactor 71, and multiple sensors are provided to detect _{the NOx} concentration in the areas corresponding to each of the above-mentioned sections 81.
In addition, the same number of outlet _NOx concentration sensors 782 as the number of each of the above-mentioned compartments 81 may be provided, or a smaller number of outlet _NOx concentration sensors 782 than the number of each of the above-mentioned compartments 81 may be used, and the sampling flow path of the exhaust gas from the area corresponding to each compartment 81 may be appropriately switched so that the _NOx concentration in all of the areas corresponding to each of the above-mentioned compartments 81 can be detected.
The outlet _NOx concentration sensor 782 constitutes an exhaust _NOx concentration acquisition unit 787 that acquires the concentration of exhaust _NOx (outlet _NOx concentration) contained in the exhaust gas flowing out from the denitrification reactor 71 .

<Regarding the Denitrification Control Device 77 According to the First Embodiment>
As shown in FIG. 4 , the denitration control device 77 according to the first embodiment includes an inlet NH ₃ concentration sensor 783 .
The inlet _NH3 concentration sensor 783 is an _NH3 concentration sensor for detecting the concentration of leak ammonia (unburned ammonia) in the exhaust gas flowing into the denitrification reactor 71 upstream of the input nozzle 74, and multiple inlet NH3 concentration sensors are provided to detect the concentration of leak ammonia (unburned ammonia) in the areas corresponding to each of the sections 81 described above.
In addition, the same number of inlet _NH3 concentration sensors 783 as the number of the above-mentioned compartments 81 may be provided, or a smaller number of inlet _NH3 concentration sensors 783 than the number of the above-mentioned compartments 81 may be used, and the sampling flow path of the exhaust gas from the area corresponding to each compartment 81 may be appropriately switched to enable detection of the concentration of leak ammonia (unburned ammonia) in all areas corresponding to each of the above-mentioned compartments 81.
The inlet NH ₃ concentration sensor 783 constitutes a leak ammonia (unburned ammonia) concentration acquisition unit 785 capable of detecting the concentration of leak ammonia (unburned ammonia) contained in the exhaust gas flowing into the denitration reactor 71 .

In the denitration control device 77 according to the first embodiment shown in Fig. 3 and Fig. 4, the mass balance calculation unit 773 calculates the input amount of the reducing agent determined from the mass balance based on the _NOx concentration (inlet _NOx concentration) of the exhaust gas flowing into each section 81 detected by the inlet _NOx concentration sensor 781, the target value (outlet _NOx concentration target value) of the _NOx concentration of the exhaust gas flowing out from the denitration reactor 71, and the flow rate (inlet gas flow rate) of the exhaust gas flowing into each section 81. Then, the mass balance calculation unit 773 outputs the input amount of the reducing agent determined from the calculated mass balance to the input amount calculation unit 771.
The inlet gas flow rate input to the mass balance calculation unit 773 is, for example, the flow rate of the combustion gas calculated based on the fuel flow rate of the boiler 10 and the oxygen concentration in the exhaust gas divided by the number of sections 81 described above.

3 and 4, the first leak ammonia (unburned ammonia) flow rate acquisition unit 772A, which is the leak ammonia (unburned ammonia) flow rate acquisition unit 772 according to the first embodiment, calculates and acquires the flow rate of leak ammonia (unburned ammonia) flowing into each section 81 based on the concentration (unburned ammonia concentration) of leak ammonia (unburned ammonia) in the exhaust gas flowing into each section 81 detected by the inlet NH ₃ concentration sensor 783 and the inlet gas flow rate described above. Then, the first leak ammonia (unburned ammonia) flow rate acquisition unit 772A outputs the acquired flow rate of leak ammonia (unburned ammonia) to the input amount calculation unit 771.

In the denitration control device 77 according to the first embodiment shown in Figures 3 and 4, an input amount calculation unit 771 calculates the amount of reducing agent input from each input nozzle 74 by subtracting the flow rate of leak ammonia (unburned ammonia) acquired by a first leak ammonia (unburned ammonia) flow rate acquisition unit 772A from the input amount of reducing agent determined from the mass balance calculated by a mass balance calculation unit 773.
Then, the denitration control device 77 outputs an opening adjustment signal to each flow rate adjustment valve 75 so that the reducing agent is injected from each injection nozzle 74 in the injection amount calculated by the injection amount calculation unit 771 .
As a result, the reducing agent is injected into the flue 13 from each injection nozzle 74 in the injection amount calculated by the injection amount calculation unit 771.

In the following description, when there is no need to distinguish between the first leak ammonia (unburned ammonia) flow rate acquisition unit 772A described above and the second leak ammonia (unburned ammonia) flow rate acquisition unit 772B and the third leak ammonia (unburned ammonia) flow rate acquisition unit 772C described below, or when the first leak ammonia (unburned ammonia) flow rate acquisition unit 772A, the second leak ammonia (unburned ammonia) flow rate acquisition unit 772B, and the third leak ammonia (unburned ammonia) flow rate acquisition unit 772C are referred to collectively, the alphabet at the end of the reference numeral will be omitted and they will simply be referred to as the leak ammonia (unburned ammonia) flow rate acquisition unit 772.

<Regarding the Denitrification Control Device 77 According to the Second Embodiment>
As shown in FIG. 7, the denitration control device 77 according to the second embodiment includes an outlet NH ₃ concentration sensor 784 .
The outlet _NH3 concentration sensor 784 is an NH3 concentration sensor for detecting the _NH3 concentration of the exhaust gas flowing out from the denitration reactor 71 downstream of the denitration reactor 71, and multiple _NH3 concentration sensors are provided to detect the _NH3 concentration in the areas corresponding to each of the sections 81 described above.
In addition, the same number of outlet _NH3 concentration sensors 784 as the number of each of the above-mentioned compartments 81 may be provided, or a smaller number of outlet _NH3 concentration sensors 784 than the number of each of the above-mentioned compartments 81 may be used, and the sampling flow path of the exhaust gas from the area corresponding to each compartment 81 may be appropriately switched so that the _NH3 concentration in all of the areas corresponding to each of the above-mentioned compartments 81 can be detected.
The outlet NH ₃ concentration sensor 784 constitutes a leak ammonia (discharge ammonia) concentration acquisition unit 786 that acquires the concentration of leak ammonia (discharge ammonia) contained in the exhaust gas flowing out from the denitration reactor 71 .

In the denitration control device 77 according to the second embodiment shown in FIG. 5 and FIG. 7, the mass balance calculation unit 773 calculates the input amount of reducing agent determined from the mass balance, similar to the mass balance calculation unit 773 of the denitration control device 77 according to the first embodiment. Then, the mass balance calculation unit 773 outputs the input amount of reducing agent determined from the calculated mass balance to the input amount calculation unit 771.

5 and 7, the second leak ammonia (unburned ammonia) flow rate acquisition unit 772B, which is the leak ammonia (unburned ammonia) flow rate acquisition unit 772 according to the second embodiment, calculates and acquires the flow rate of leak ammonia (unburned ammonia) flowing into each section 81 based on the concentration of NH ₃ in the exhaust gas flowing out from each section 81 (concentration of leak ammonia (discharged ammonia)) detected by the outlet _{NH 3} concentration sensor 784, the inlet gas flow rate described above, and the amount of reducing agent introduced immediately before. Note that, when calculating the flow rate of leak ammonia (unburned ammonia) flowing into each section 81, the second leak ammonia (unburned ammonia) flow rate acquisition unit 772B uses the inlet gas flow rate as the flow rate of exhaust gas flowing out from each section 81 (outlet gas flow rate).
The second leak ammonia (unburned ammonia) flow rate acquisition unit 772B outputs the acquired flow rate of leak ammonia (unburned ammonia) to the input amount calculation unit 771.

In the denitration control device 77 according to the second embodiment shown in Figures 5 and 7, an input amount calculation unit 771 calculates the amount of reducing agent input from each input nozzle 74 by subtracting the flow rate of leak ammonia (unburned ammonia) acquired by a second leak ammonia (unburned ammonia) flow rate acquisition unit 772B from the input amount of reducing agent determined from the mass balance calculated by a mass balance calculation unit 773.
Then, the denitration control device 77 outputs an opening adjustment signal to each flow rate adjustment valve 75 so that the reducing agent is injected from each injection nozzle 74 in the injection amount calculated by the injection amount calculation unit 771 .
As a result, the reducing agent is injected into the flue 13 from each injection nozzle 74 in the injection amount calculated by the injection amount calculation unit 771.

In addition, a relatively high concentration of leak ammonia (exhaust ammonia) indicates that the amount of leak ammonia (unburned ammonia) is large, and therefore the amount of reducing agent injected calculated by mass analysis is excessive.
In the denitration control device 77 according to the second embodiment shown in Figures 5 and 7, the concentration of leaked ammonia (emitted ammonia) contained in the exhaust gas flowing out from the denitration reactor 71 can be obtained, making it easier to suppress the ammonia flowing out downstream of the denitration reactor 71 and also suppressing excessive input of reducing agent, thereby reducing the cost of the reducing agent.
<Regarding the denitrification control device 77 according to the third embodiment>
As shown in FIG. 6, the denitration control device 77 according to the third embodiment is equipped with a correction amount calculation unit 774 that calculates _a correction amount for the amount of reducing agent injected based on the _NOx concentration (outlet _NOx concentration) of the exhaust gas flowing out from the denitration reactor 71 detected by the outlet NOx concentration sensor 782 and the outlet gas flow rate (i.e., inlet gas flow rate).
As shown in FIG. 7, the denitration control device 77 according to the third embodiment includes an outlet NH ₃ concentration sensor 784 .

In the denitration control device 77 according to the third embodiment shown in FIG. 6 and FIG. 7, the mass balance calculation unit 773 calculates the input amount of reducing agent determined from the mass balance, similar to the mass balance calculation unit 773 of the denitration control device 77 according to the first and second embodiments. Then, the mass balance calculation unit 773 outputs the input amount of reducing agent determined from the calculated mass balance to the input amount calculation unit 771.

The second leak ammonia (unburned ammonia) flow rate acquisition unit 772B, which is the leak ammonia (unburned ammonia) flow rate acquisition unit 772 of the denitration control device 77 according to the third embodiment shown in FIG. 6 and FIG. 7, calculates and acquires the flow rate of the leak ammonia (unburned ammonia) flowing into each section 81 based on the concentration of the leak ammonia (discharged ammonia), the inlet gas flow rate described above, and the amount of reducing agent introduced immediately before, as in the second embodiment. Then, the second leak ammonia (unburned ammonia) flow rate acquisition unit 772B outputs the acquired flow rate of the leak ammonia (unburned ammonia) to the input amount calculation unit 771.

In the denitration control device 77 according to the third embodiment shown in Fig. 6 and Fig. 7, a correction amount calculation unit 774 calculates the flow rate of _NOx flowing out from the denitration reactor 71 based on the outlet _NOx concentration and the inlet gas flow rate. Since the flow rate of _NOx flowing out from the denitration reactor 71 reflects a shortage in the amount of reducing agent introduced immediately before, the correction amount calculation unit 774 calculates a correction amount for the introduction amount of reducing agent according to the calculated flow rate of _NOx flowing out from the denitration reactor 71. Then, the correction amount calculation unit 774 outputs the calculated correction amount for the introduction amount of reducing agent to the introduction amount calculation unit 771.

In the denitration control device 77 according to the third embodiment shown in FIGS. 6 and 7 , an input amount calculation unit 771 calculates the amount of reducing agent input from each input nozzle 74 by subtracting the flow rate of leak ammonia (unburned ammonia) acquired by a second leak ammonia (unburned ammonia) flow rate acquisition unit 772B from the input amount of reducing agent determined from the mass balance calculated by a mass balance calculation unit 773, and adding a correction amount of the input amount of reducing agent calculated by a correction amount calculation unit 774.
Then, the denitration control device 77 outputs an opening adjustment signal to each flow rate adjustment valve 75 so that the reducing agent is injected from each injection nozzle 74 in the injection amount calculated by the injection amount calculation unit 771 .
As a result, the reducing agent is injected into the flue 13 from each injection nozzle 74 in the injection amount calculated by the injection amount calculation unit 771.

In the denitration control device 77 of the third embodiment shown in Figures 6 and 7, when the concentration of exhaust _NOx (outlet _NOx concentration) obtained by the outlet _NOx concentration sensor 782 is relatively high, this means that the amount of reducing agent being fed is insufficient, and the outlet _NOx concentration can be suppressed by increasing the amount of reducing agent being fed based on the correction amount of the reducing agent being fed calculated by the correction amount calculation unit 774.

<Regarding the Denitrification Control Device 77 According to the Fourth Embodiment>
As shown in FIG. 8, the denitration control device 77 according to the fourth embodiment includes a difference calculation unit 775 that calculates the difference between the outlet _NOx concentration detected by the outlet _NOx concentration sensor 782 and the target outlet _NOx concentration value.

In the denitration control device 77 according to the fourth embodiment shown in FIG. 8 and FIG. 9, the mass balance calculation unit 773 calculates the input amount of reducing agent determined from the mass balance, similar to the mass balance calculation unit 773 of the denitration control device 77 according to the first, second, and third embodiments. Then, the mass balance calculation unit 773 outputs the input amount of reducing agent determined from the calculated mass balance to the input amount calculation unit 771.

In the denitration control device 77 according to the fourth embodiment shown in Figures 8 and 9, a difference calculation unit 775 calculates the difference between the outlet _NOx concentration and the outlet _NOx concentration target value, and outputs it to a third leak ammonia (unburned ammonia) flow rate acquisition unit 772C, which is the leak ammonia (unburned ammonia) flow rate acquisition unit 772 of the denitration control device 77 according to the fourth embodiment.
Here, the reason why a difference occurs between the outlet _NOx concentration and the outlet _NOx concentration target value is considered to be because leak ammonia (unburned ammonia) was contained in the exhaust gas flowing into the denitration reactor 71. In other words, when the outlet _NOx concentration is a value lower than the outlet _NOx concentration target, the difference between the outlet _NOx concentration and the outlet _NOx concentration target value can be considered to be due to the leak ammonia (unburned ammonia) being used for denitration. Therefore, the difference between the outlet _NOx concentration and the outlet _NOx concentration target value is a value according to the amount of leak ammonia (unburned ammonia).

8 and 9, a third leak ammonia (unburned ammonia) flow rate acquisition unit 772C calculates and acquires the flow rate of leak ammonia (unburned ammonia) flowing into each section 81 based on the difference, the inlet _NOx concentration, and the inlet gas flow rate. Then, a second leak ammonia (unburned ammonia) flow rate acquisition unit 772B outputs the acquired flow rate of leak ammonia (unburned ammonia) to the input amount calculation unit 771.

In the denitration control device 77 according to the fourth embodiment shown in Figures 8 and 9, an input amount calculation unit 771 calculates the amount of reducing agent input from each input nozzle 74 by subtracting the flow rate of leak ammonia (unburned ammonia) acquired by a third leak ammonia (unburned ammonia) flow rate acquisition unit 772C from the input amount of reducing agent determined from the mass balance calculated by a mass balance calculation unit 773.
Then, the denitration control device 77 outputs an opening adjustment signal to each flow rate adjustment valve 75 so that the reducing agent is injected from each injection nozzle 74 in the injection amount calculated by the injection amount calculation unit 771 .
As a result, the reducing agent is injected into the flue 13 from each injection nozzle 74 in the injection amount calculated by the injection amount calculation unit 771.

In the denitration control device 77 of the fourth embodiment shown in Figures 8 and 9, the flow rate of leaked ammonia (unburned ammonia) can be obtained based on the concentration of exhaust _NOx (outlet _NOx concentration) contained in the exhaust gas flowing out from the denitration reactor 71. Therefore, compared to detecting the concentration of leaked ammonia (unburned ammonia) contained in the exhaust gas flowing into the denitration reactor 71 or detecting the concentration of leaked ammonia (emitted ammonia) contained in the exhaust gas flowing out from the denitration reactor 71, measuring equipment can be procured relatively cheaply.

As described above regarding the control of the amount of reducing agent injected, the denitration control device 77 of this embodiment is equipped with an injection amount calculation unit 771, so that the amount of reducing agent injected can be calculated based on the excess amount of reducing agent taking into account leak ammonia (unburned ammonia), and ammonia flowing out downstream of the denitration reactor 71 can be suppressed.

The denitration device 70 of the present embodiment includes a denitration control device 77 according to any one of the embodiments described above, a denitration reactor 71, and a reducing agent injection section 73 for injecting a reducing agent into exhaust gas.
This makes it possible to suppress ammonia flowing out downstream of the denitration reactor 71 .

In the denitration control device 77 of the present embodiment, the input amount calculation unit 771 is configured to calculate the input amount of the reducing agent to be input to each of the multiple sections 81 .
This allows the amount of reducing agent to be calculated based on the distribution of the flow rate (concentration) of leaked ammonia (unburned ammonia) in a cross section of the denitration reactor 71 perpendicular to the flow of exhaust gas, thereby efficiently suppressing ammonia flowing downstream of the denitration reactor 71.

In the denitration control device 77 of this embodiment, the input amount calculation unit 771 is configured to calculate the input amount of reducing agent based on the flow rate of leak ammonia (unburned ammonia) acquired by the leak ammonia (unburned ammonia) flow rate acquisition unit 772.
This allows the amount of reducing agent introduced to be adjusted accurately, and therefore, while the amount of _NOx flowing out downstream of the denitration reactor 71 is sufficiently suppressed, the amount of ammonia flowing out downstream of the denitration reactor 71 is also suppressed.

In the denitration control device 77 of the present embodiment, the leak ammonia (unburned ammonia) flow rate acquisition unit 772 is configured to acquire the flow rate of the leak ammonia (unburned ammonia) based on the concentration of the leak ammonia (unburned ammonia) acquired by the inlet _NH3 concentration sensor 783 constituting the leak ammonia (unburned ammonia) concentration acquisition unit 785 and the flow rate of the exhaust gas flowing into the denitration reactor 71 (inlet gas flow rate).
As a result, the flow rate of unburned ammonia flowing into the denitration reactor 71 can be obtained based on the detected concentration of leak ammonia (unburned ammonia) contained in the exhaust gas flowing into the denitration reactor 71, so that the flow rate of leak ammonia (unburned ammonia) flowing into the denitration reactor 71 can be obtained relatively accurately. Therefore, the amount of reducing agent injected can be accurately optimized, and the ammonia flowing out downstream of the denitration reactor 71 can be suppressed while sufficiently suppressing _NOx flowing out downstream of the denitration reactor 71.

<Regarding the inlet _NH3 concentration sensor 783>
The inlet _NH3 concentration sensor 783 described above may be, for example, a gas analyzer capable of directly detecting the _NH3 concentration.
Furthermore, the inlet NH ₃ concentration sensor 783 may be, for example, an infrared CT device.
Furthermore, in detecting the inlet _NH3 concentration, the inlet _NH3 concentration may be estimated from an image of the combustion flame in the boiler 10 as follows. That is, a prediction model of the inlet _NH3 concentration is created by machine learning in advance the relationship between the image of the flame in the boiler 10 and the inlet _NH3 concentration. Then, an imaging device 79 capable of imaging the flame of the boiler 10 (see FIG. 1 ) may be provided in the boiler 10, and the inlet _NH3 concentration may be estimated based on the image of the flame captured by the imaging device 79 and the prediction model of the inlet _NH3 concentration.
FIG. 10 is a block diagram for estimating the inlet NH ₃ concentration (unburned ammonia concentration) using a prediction model for the inlet NH ₃ concentration.
The denitration control device 77 shown in FIG. 10 is equipped with a leak ammonia (unburned ammonia) concentration estimation unit 776 that estimates the concentration of leak ammonia (unburned ammonia) contained in the exhaust gas flowing into the denitration reactor 71 from an image of a flame captured by an imaging device 79 provided in the boiler 10.
The leak ammonia (unburned ammonia) concentration estimation unit 776 estimates the inlet NH ₃ concentration in the exhaust gas flowing into each section 81 using a prediction model of the inlet NH ₃ concentration from an image of the flame captured by the imaging device 79.
This makes it possible to estimate the concentration of leaked ammonia (unburned ammonia) with a relatively simple configuration.

<Regarding the outlet _NH3 concentration sensor 784>
The above-mentioned outlet _NH3 concentration sensor 784 may be, for example, a gas analyzer capable of directly detecting the _NH3 concentration.
Furthermore, the above-mentioned outlet NH ₃ concentration sensor 784 may be, for example, an infrared CT device.

<Regarding the inlet _NOx concentration sensor 781>
The inlet _NOx concentration sensor 781 described above may be, for example, a gas analyzer capable of directly detecting the _NOx concentration.
Furthermore, the above-mentioned inlet _NOx concentration sensor 781 may be, for example, an infrared CT device.
Furthermore, for the detection of the inlet _NOx concentration, the inlet _NOx concentration may be estimated from an image of the combustion flame in the boiler 10 as follows. That is, a prediction model of the inlet _NOx concentration is created by machine learning in advance the relationship between the image of the flame in the boiler 10 and the inlet _NOx concentration. Then, an imaging device 79 capable of imaging the flame of the boiler 10 is provided in the boiler 10 (see FIG. 1), and the inlet _NOx concentration may be estimated based on the image of the flame captured by the imaging device 79 and the prediction model of the inlet _NOx concentration.
FIG. 11 is a block diagram for estimating the inlet _NOx concentration using a prediction model for the inlet _NOx concentration.
The denitration control device 77 shown in Figure 11 is equipped with an inlet NOx concentration estimation unit 777 that estimates the concentration of _NOx (inlet _NOx concentration) contained in the exhaust gas flowing into the denitration reactor 71 from an image of the flame captured by an _imaging device 79 installed in the boiler 10.
The inlet _NOx concentration estimation unit 777 estimates the inlet _NOx concentration in the exhaust gas flowing into each section 81 using a prediction model of the inlet _NOx concentration from an image of the flame captured by the imaging device 79 .

<Regarding the outlet _NOx concentration sensor 782>
The above-mentioned outlet _NOx concentration sensor 782 may be, for example, a gas analyzer that can directly detect the _NOx concentration.
Furthermore, the above-mentioned outlet _NOx concentration sensor 782 may be, for example, an infrared CT device.

The present disclosure is not limited to the above-described embodiments, and includes modifications to the above-described embodiments and appropriate combinations of these modifications.
For example, in the above description, the boiler system 1 has been used as an example of a combustion device according to some embodiments, but the combustion device according to some embodiments is not limited to the boiler system 1 and may be a gas turbine or an industrial furnace.

In the above description, the cross section of the denitrification reactor 71 is divided into multiple compartments 81, and an input nozzle 74 and a flow control valve 75 are disposed in each compartment 81. However, the number of compartments 81 may be increased or decreased as appropriate depending on the scale of the combustion device in some embodiments, and in cases where the device is relatively small, the cross section of the denitrification reactor 71 does not need to be divided into multiple compartments 81.

The contents described in each of the above embodiments can be understood, for example, as follows.
(1) A denitration control device 77 according to at least one embodiment of the present disclosure is a control device for a denitration device 70 including a denitration reactor 71 for removing nitrogen oxides from exhaust gas discharged from a combustion device (boiler 10) that uses ammonia as fuel. The denitration control device 77 according to at least one embodiment of the present disclosure includes an input amount calculation unit 771 that calculates an input amount of reducing agent based on an excess amount of reducing agent taking into account leak ammonia (unburned ammonia).

According to the above configuration (1), the amount of reducing agent to be injected is calculated based on the excess amount of reducing agent taking into account leak ammonia (unburned ammonia), so that the amount of ammonia flowing downstream of the denitrification reactor 71 can be suppressed.

(2) In some embodiments, the configuration of (1) above may include an unburned ammonia flow rate acquisition unit (leak ammonia (unburned ammonia) flow rate acquisition unit 772) configured to acquire the flow rate of leak ammonia (unburned ammonia) flowing into the denitrification reactor 71. The input amount calculation unit 771 may be configured to calculate the input amount of reducing agent based on the flow rate of leak ammonia (unburned ammonia) acquired by the unburned ammonia flow rate acquisition unit (leak ammonia (unburned ammonia) flow rate acquisition unit 772).

According to the above configuration (2), the amount of reducing agent to be introduced is calculated based on the flow rate of leak ammonia (unburned ammonia) flowing into the denitration reactor 71 acquired by the unburned ammonia flow rate acquisition unit (leak ammonia (unburned ammonia) flow rate acquisition unit 772), so that the amount of reducing agent to be introduced can be accurately optimized. This makes it possible to sufficiently suppress _NOx flowing out downstream of the denitration reactor 71 while also suppressing ammonia flowing out downstream of the denitration reactor 71.

(3) In some embodiments, in the configuration of (2) above, an unburned ammonia concentration acquisition unit (leak ammonia (unburned ammonia) concentration acquisition unit 785) capable of detecting the concentration of leak ammonia (unburned ammonia) contained in the exhaust gas flowing into the denitration reactor 71 may be provided. The unburned ammonia flow rate acquisition unit (leak ammonia (unburned ammonia) flow rate acquisition unit 772) may be configured to acquire the flow rate of leak ammonia (unburned ammonia) based on the concentration of leak ammonia (unburned ammonia) acquired by the unburned ammonia concentration acquisition unit (leak ammonia (unburned ammonia) concentration acquisition unit 785) and the flow rate of the exhaust gas flowing into the denitration reactor 71.

According to the above configuration (3), since the flow rate of the leak ammonia (unburned ammonia) flowing into the denitration reactor 71 can be obtained based on the detected concentration of the leak ammonia (unburned ammonia) contained in the exhaust gas flowing into the denitration reactor 71, the flow rate of the leak ammonia (unburned ammonia) flowing into the denitration reactor 71 can be obtained relatively accurately. This allows the amount of reducing agent injected to be accurately optimized, and the ammonia flowing out downstream of the denitration reactor 71 can be suppressed while sufficiently suppressing _NOx flowing out downstream of the denitration reactor 71.

(4) In some embodiments, the configuration of (2) above may include an imaging device 79 capable of imaging the flame in the combustion device (boiler 10), and an unburned ammonia concentration estimation unit (leak ammonia (unburned ammonia) concentration estimation unit 776) that estimates the concentration of leak ammonia (unburned ammonia) contained in the exhaust gas flowing into the denitrification reactor from the image of the flame captured by the imaging device 79. The unburned ammonia flow rate acquisition unit (leak ammonia (unburned ammonia) flow rate acquisition unit 772) may be configured to acquire the flow rate of leak ammonia (unburned ammonia) based on the concentration of leak ammonia (unburned ammonia) estimated by the unburned ammonia concentration estimation unit (leak ammonia (unburned ammonia) concentration estimation unit 776) and the flow rate of the exhaust gas flowing into the denitrification reactor 71.

The configuration (4) above makes it possible to estimate the concentration of leak ammonia (unburned ammonia) with a relatively simple configuration.

(5) In some embodiments, the configuration of (2) above may include an exhaust ammonia concentration acquisition unit (leak ammonia (exhaust ammonia) concentration acquisition unit 786) that acquires the concentration of leak ammonia (exhaust ammonia) contained in the exhaust gas flowing out from the denitrification reactor 71. The unburned ammonia flow rate acquisition unit (leak ammonia (exhaust ammonia) flow rate acquisition unit 772) may be configured to acquire the flow rate of leak ammonia (unburned ammonia) based on the concentration of leak ammonia (exhaust ammonia) acquired by the exhaust ammonia concentration acquisition unit (leak ammonia (exhaust ammonia) concentration acquisition unit 786) and the flow rate of the exhaust gas flowing out from the denitrification reactor 71.

A relatively high concentration of leak ammonia (exhaust ammonia) indicates that the amount of reducing agent injected is excessive.
According to the above configuration (5), the concentration of exhaust ammonia contained in the exhaust gas flowing out from the denitration reactor 71 can be obtained, making it easier to suppress the ammonia flowing out downstream of the denitration reactor 71 and suppressing the excessive input of reducing agent, thereby reducing the cost of the reducing agent.

(6) In some embodiments, the configuration of (5) above may include an exhaust _NOx concentration acquisition unit 787 that acquires the concentration of exhaust _NOx contained in the exhaust gas flowing out from the denitrification reactor 71, and a correction amount calculation unit 774 that calculates a correction amount for the amount of reducing agent added based on the concentration of exhaust _NOx acquired by the exhaust _NOx concentration acquisition unit 787.

According to the above configuration (6), when the concentration _of exhaust _NOx acquired by the exhaust NOx concentration acquisition unit 787 is relatively high, this means that the amount of reducing agent being added is insufficient. Therefore, by increasing the amount of reducing agent being added based on the correction amount of the reducing agent being added calculated by the correction amount calculation unit 774, the concentration of exhaust _NOx contained in the exhaust gas flowing out from the denitrification reactor 71 can be suppressed.

(7) In some embodiments, the configuration of (2) above may include an exhaust _NOx concentration acquisition unit 787 that acquires the concentration of exhaust _NOx contained in the exhaust gas flowing out from the denitrification reactor 71, and a difference calculation unit 775 that calculates the difference between the concentration of exhaust _NOx acquired by the exhaust _NOx concentration acquisition unit 787 and a target value of the concentration of exhaust _NOx . The unburned ammonia flow rate acquisition unit (leak ammonia (unburned ammonia) flow rate acquisition unit 772) may be configured to acquire the flow rate of leak ammonia (unburned ammonia) based on the difference calculated by the difference calculation unit 775.

According to the above configuration (7), the flow rate of leak ammonia (unburned ammonia) can be obtained based on the concentration of exhaust _NOx contained in the exhaust gas flowing out from the denitration reactor 71. Therefore, compared to detecting the concentration of leak ammonia (unburned ammonia) contained in the exhaust gas flowing into the denitration reactor 71 or detecting the concentration of leak ammonia (emitted ammonia) contained in the exhaust gas flowing out from the denitration reactor 71, the measuring equipment can be procured relatively cheaply.

(8) In some embodiments, in any of the configurations (2) to (7) above, the unburned ammonia flow rate acquisition unit (leak ammonia (unburned ammonia) flow rate acquisition unit 772) may be configured to acquire the flow rate of leak ammonia (unburned ammonia) flowing into each of the multiple compartments 81 obtained by dividing the cross section of the denitration reactor 71 perpendicular to the flow of exhaust gas. The input amount calculation unit 771 may be configured to calculate the input amount of reducing agent to be input into each of the multiple compartments 81.

According to the above configuration (8), the amount of reducing agent to be injected can be calculated according to the distribution of the flow rate (concentration) of leaked ammonia (unburned ammonia) in the cross section of the denitration reactor 71 perpendicular to the flow of exhaust gas, so that ammonia flowing downstream of the denitration reactor 71 can be efficiently suppressed.

(9) A denitration device 70 according to at least one embodiment of the present disclosure includes a denitration control device 77 having any of the configurations (1) to (8) above, a denitration reactor 71, and a reducing agent injection section 73 for injecting a reducing agent into the exhaust gas.

The above configuration (9) can suppress ammonia flowing downstream of the denitrification reactor 71.

Reference Signs List 1 Boiler system 10 Boiler 70 Denitration device 71 Denitration reactor 73 Reducing agent supply unit 79 Imaging device 81 Section 771 Supply amount calculation unit 772 Unburned ammonia flow rate acquisition unit (leak ammonia (unburned ammonia) flow rate acquisition unit)
774: correction amount calculation unit 775: difference calculation unit 776: unburned ammonia concentration estimation unit (leak ammonia (unburned ammonia) concentration estimation unit)
785 Unburned ammonia concentration acquisition unit (leak ammonia (unburned ammonia) concentration acquisition unit)
786 Discharge ammonia concentration acquisition unit (leak ammonia (discharge ammonia) concentration acquisition unit)
787 Exhaust _NOx concentration acquisition unit

Claims (9)

A control device for a denitration device having a denitration reactor for removing nitrogen oxides from exhaust gas discharged from a combustion device using ammonia as fuel,
an input amount calculation unit that calculates an input amount of the reducing agent based on an excess amount of the reducing agent taking into account unburned ammonia;
Equipped with
Denitrification control device. an unburned ammonia flow rate acquisition unit configured to acquire a flow rate of the unburned ammonia flowing into the denitrification reactor;
Equipped with
The input amount calculation unit calculates the input amount of the reducing agent based on the flow rate of the unburned ammonia acquired by the unburned ammonia flow rate acquisition unit.
The denitrification control device according to claim 1 . an unburned ammonia concentration acquisition unit capable of detecting the concentration of the unburned ammonia contained in the exhaust gas flowing into the denitration reactor;
Equipped with
the unburned ammonia flow rate acquisition unit acquires a flow rate of the unburned ammonia based on the concentration of the unburned ammonia acquired by the unburned ammonia concentration acquisition unit and a flow rate of the exhaust gas flowing into the denitrification reactor.
The denitrification control device according to claim 2 . an imaging device capable of imaging a flame in the combustion device;
an unburned ammonia concentration estimation unit that estimates a concentration of the unburned ammonia contained in the exhaust gas flowing into the denitration reactor from an image of the flame captured by the imaging device;
Equipped with
the unburned ammonia flow rate acquisition unit acquires a flow rate of the unburned ammonia based on the concentration of the unburned ammonia estimated by the unburned ammonia concentration estimation unit and a flow rate of the exhaust gas flowing into the denitrification reactor.
The denitrification control device according to claim 2 . an emission ammonia concentration acquisition unit that acquires a concentration of emission ammonia contained in the exhaust gas flowing out from the denitrification reactor;
Equipped with
the unburned ammonia flow rate acquisition unit acquires a flow rate of the unburned ammonia based on the concentration of the discharged ammonia acquired by the discharged ammonia concentration acquisition unit and a flow rate of the exhaust gas flowing out from the denitrification reactor.
The denitrification control device according to claim 2 . an exhaust _NOx concentration acquisition unit that acquires a concentration of exhaust _NOx contained in the exhaust gas flowing out from the denitrification reactor;
a correction _amount calculation unit that calculates a correction amount of the input amount of the reducing agent based on the concentration of the exhaust _NOx acquired by the exhaust NOx concentration acquisition unit;
Equipped with
The denitrification control device according to claim 5 . an exhaust _NOx concentration acquisition unit that acquires a concentration of exhaust _NOx contained in the exhaust gas flowing out from the denitrification reactor;
a difference calculation unit that calculates a difference between the concentration of the exhaust _NOx acquired by the exhaust _NOx concentration acquisition unit and a target value of the concentration of the exhaust _NOx ;
Equipped with
the unburned ammonia flow rate acquisition unit acquires a flow rate of the unburned ammonia based on the difference calculated by the difference calculation unit.
The denitrification control device according to claim 2 . the unburned ammonia flow rate acquisition unit is configured to acquire a flow rate of the unburned ammonia flowing into each of a plurality of sections obtained by dividing a cross section of the denitration reactor perpendicular to the flow of the exhaust gas,
The input amount calculation unit calculates an input amount of the reducing agent to be input into each of the plurality of compartments.
The denitrification control device according to claim 2 or 3. The denitrification control device according to claim 1 or 2,
The denitrification reactor;
A reducing agent input unit for inputting the reducing agent into the exhaust gas;
Equipped with
Denitrification equipment.

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