JPH0880423A - Denitrification controller - Google Patents

Abstract

PURPOSE: To obtain a safe denitrification controller coping with a NOx regulating value even on startup by inputting extinguishing time on ignition of a gas turbine to calculate the minimum opening degree of an ammonia flow control valve by an arithmetic unit and controlling the lower limit of a control signal. CONSTITUTION: On startup, unreacted NH3 is discharged from a stack because of temperature characteristics of a catalyst. To prevent this fact, a function generator 42 inputs extinguishing time t and outputs a minimum opening degree m. Just after ignition, a contact 43 is operated, and the minimum opening degree m and output of the 2nd PI controller 40 are inputted to a low value controller 41. Therefore, a control signal S12 being outputted of the low value controller 41 is equalized to the minimum degree opening m to control the opening degree of an ammonia flow control valve 32 to the minimum opening degree m. At that time, ammonia injected into the catalyst is reacted only a little, but ammonia adsorbed in the catalyst is dissociated during stoppage and the adsorbed quantity of ammonia is reduced, thereby the injected ammonia is almost adsorbed and its dissociated quantity is small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a denitration control device for a combined cycle power plant, and more particularly to a denitration control device employing a selective catalytic reduction method using ammonia.

[0002]

2. Description of the Related Art In recent years, an increase in energy demand has led to an increase in the amount of energy supplied by fossil fuels, which in turn has led to an increase in CO ₂ emissions. For this reason, the crisis of global warming has been exclaimed, and CO ₂ emission has come to be regulated on a global scale. From such a background, since a combined cycle power plant combining a gas turbine cycle and a steam turbine cycle can be expected to have high efficiency, it is expected to lead to a reduction in CO ₂ .

A conventional combined cycle power plant will be described below with reference to the system diagram shown in FIG. As shown in the figure, the combined cycle power plant includes a gas turbine device 1, an exhaust heat recovery boiler device 2 that generates steam by using exhaust gas thereof as a heat source,
A steam turbine device 3 that uses this generated steam as drive steam;
It is composed of a chimney 4.

The gas turbine system 1 is operated by an air compressor 7 for pressurizing the introduced air 6, a combustor 9 for combusting the compressed air with fuel supplied from a fuel system 8, and a combustion gas generated by the combustion. A gas turbine 10 and a generator 11 that takes a load are provided. Further, the exhaust heat recovery boiler device 2 includes a superheater 13, an evaporator 14, a denitrification device 15, along the upstream side and the downstream side of the flue 12 through which the exhaust gas flow 5 flows.
It is equipped with a economizer 16. The steam generated in the superheater 13 is guided to the steam turbine device 3 through the steam pipe 17. In the steam turbine device 3, a load is taken by the generator 19, the water is condensed from the steam turbine 18 through the condenser 20, and then the water is fed to the economizer 16 by the water supply pipe 21. This feed water is superheated in the economizer 16, evaporated in the evaporator 14,
Further, it is overheated by the superheater 13. Further, this feed water is superheated and evaporated in the evaporator 14 while being forcedly circulated or naturally circulated by a temperature difference.

It has been researched to raise the combustion temperature in order to increase the efficiency of the combined power plant having the above-mentioned structure and relatively reduce CO _2. However, when the combustion temperature is raised, the gas is discharged from the gas turbine unit 1. The nitrogen oxides NOx that are generated increase exponentially with temperature. This nitrogen oxide NO
As a measure to reduce the concentration of x, a method of injecting water or steam into the combustor 9 to lower the fuel temperature, and a method of premixing by mixing the fuel and air to prevent local high temperature parts and leading to the combustor 9 There is a two-stage combustion method for averaging the combustion temperature.

However, it is difficult to achieve the regulation value of the nitrogen oxide NOx only by these methods. Therefore, the denitration device 15 is installed in the exhaust gas passage. The denitration device 15 employs ammonia injection, which is one of denitration methods, and a dry selective catalytic reduction decomposition method. This denitration system is a system in which ammonia is injected into the exhaust gas from the ammonia injection system 23 and the nitrogen oxide is reduced and decomposed into harmless nitrogen and steam by passing through the catalyst 22 on the downstream side thereof. Depending on the temperature characteristics of the catalyst
It is installed between the evaporator 14 and the economizer 16 because of its good reaction efficiency. Such control of the denitration device 15 is performed by the amount of ammonia injected from the ammonia injection system 23.

A control method of the conventional denitration control device will be described below with reference to the block diagram of FIG. In the block diagram of FIG. 15, the denitration control device 30 takes a difference between the NOx concentration detection value S2 and the NOx concentration set value S1 and outputs the NOx concentration deviation signal S3, and the NOx concentration deviation signal S3. As the input, a first PI controller 34 that performs a feedback process, an FF controller 35 that performs a feedforward process on the water injection amount signal S4 to the combustor, and a first PI controller 34
Second adder 36 for converting the output of the PI controller 34 and the output of the FF controller 35 to output the molar ratio setting signal S5.
A first divider 37 that divides the ammonia flow rate signal S6 by the gas flow rate S7 and outputs an ammonia concentration signal S8;
A second divider 38 that divides the ammonia concentration signal S8 by the predicted NOx signal S9 and outputs a molar ratio predicted signal S10;
A third adder 39 that takes the difference between the molar ratio setting signal S5 and the molar ratio prediction signal S10 and outputs the molar ratio deviation signal S11.
And the second PI controller 40 that receives the molar ratio deviation signal S11 as input and outputs the control signal S12 by performing feedback processing, and the exhaust gas temperature detection value S13 as input and the exhaust gas temperature of the gas turbine 1 is the characteristic of the catalyst 22. Output from the second PI controller 40 is fully closed by a comparator 44 driven by the comparator 44 to detect that the temperature exceeds a predetermined temperature determined by the above and operating the contact 45 in a closed state. And a contact 45 for tracking the state.

[0008] As described above, NOx determined by regulation etc.
The NOx concentration deviation signal S3 is obtained by the first adder 33 from the concentration set value S1 and the NOx concentration detection value S2 discharged from the plant, and is input to the first PI controller 34 having a negative gain. Further, the water injection amount signal S4 is input to the FF controller 35 having a negative gain. The output of the first PI controller 34 and the output of the FF controller 35 are added by the second adder 36 and become the molar ratio setting signal S5. The ammonia flow rate signal S6 is divided by the gas flow rate S7 in the first divider 37 to become the ammonia concentration signal S8. Further, the ammonia concentration signal S8 is divided by the predicted NOx signal S9 in the second divider 38 to become the molar ratio predicted signal S10. The third adder 39 uses the molar ratio setting signal S5 and the molar ratio prediction signal S
The difference with 10 is taken and the mole ratio deviation signal S11 is output.
The molar ratio deviation signal S11 is subjected to feedback processing by the second PI controller 40 and becomes a control signal S12.

Therefore, when the NOx concentration detection value S2 increases, the NOx concentration deviation signal S3 becomes a negative value, and the output of the first PI controller 34 having a negative gain and the molar ratio setting signal S5 increase. Due to this increase, the mole ratio deviation signal S1
1. Since the control signal S12 also increases, the actuator 31
The NH ₃ flow rate adjusting valve 32 is opened via the valve to increase the injection amount of ammonia. Further, when the water injection amount signal S4 increases, the output of the FF controller 35 having a negative gain and the molar ratio setting signal S5 decrease. Due to this decrease, the mole ratio deviation signal S11 decreases and the control signal S12 also decreases, so the NH ₃ flow rate adjusting valve 32 is closed via the actuator 31, and the injection amount of ammonia decreases.

When the temperature of the catalyst 22 is lower than a predetermined temperature determined by the characteristics at the time of start-up, unreacted NH ₃ is discharged from the stack 4 because the action of the catalyst 22 is not effective. In order to prevent this, the comparator 44 detects that the exhaust gas temperature of the gas turbine 1 has reached a predetermined temperature determined by the characteristics of the catalyst 22 or more, operates the contact 45 in the closed state, and outputs the fully closed signal S14. By tracking the output of the second PI controller 40 to the fully closed state, the NH ₃ valve is fully closed to prevent the useless injection of ammonia and suppress the discharge of unreacted NH _{3 from} the stack 4. ing.

As described above, the molar ratio control function based on the predicted NOx signal S9 that includes an error but can be input at high speed, and the NOx concentration detection value S2 that has a large delay but is accurate.
By combining the molar ratio setting function based on the above with a cascade method, it is possible to perform high-speed and accurate control by extracting the advantages of both. Further, since the molar ratio setting system can back up the error due to the predicted NOx in the molar ratio control system and the characteristic variation due to aging, safe and stable control becomes possible. Further, even when the temperature of the catalyst 22 is low at the time of start-up, useless injection of ammonia can be prevented, so that effective denitration control becomes possible.

[0012]

However, in the above-mentioned conventional technique, when the temperature of the catalyst 22 at the time of starting is low, ammonia is not injected, so that NOx generated by the gas turbine device 1 is directly discharged from the chimney 4. Therefore, there is a possibility that the NOx regulation value, which becomes stricter year by year, cannot be met.

The present invention has been made in order to cope with the above situation, and its purpose is to be severer year after year even at startup.
The object is to provide a flexible and safe denitration control device that can comply with the x regulation value and can suppress the discharge of unreacted NH _{3 from} the chimney.

[0014]

In order to achieve the above object, the first aspect of the present invention is to spray the mixed ammonia of diluted air onto the exhaust gas of a gas turbine of a combined power generation facility comprising a gas turbine and a steam turbine. A detector for detecting the state quantity of the gas turbine in a denitration controller for controlling NOx concentration of exhaust gas by increasing / decreasing an ammonia injection amount in a dry denitration device for removing nitrogen oxides by a chemical reaction with a catalyst And a calculation device that calculates the minimum opening of the ammonia flow rate adjusting valve based on the detection value detected by the detector, and a low value limit that controls the opening of the ammonia flow rate adjusting valve so as not to fall below the minimum opening. And a means for opening the ammonia flow rate adjusting valve according to the state quantity of the gas turbine at the time of starting the combined cycle power generation facility to be equal to or less than the minimum opening degree. And controlling only during predetermined so as not.

According to a second aspect of the present invention, in the denitration control device according to the first aspect, the state quantity of the gas turbine is an extinguishing time when the gas turbine is ignited. According to a third aspect of the present invention, in the denitration control device according to the first aspect, the state quantity of the gas turbine is an extinguishing time at the time of ignition of the gas turbine and a suction temperature of the compressor.

According to a fourth aspect of the present invention, in the denitration control device according to the first aspect, the state quantity of the gas turbine is the extinguishing time at the time of ignition of the gas turbine and the atmospheric temperature. According to a fifth aspect of the present invention, in the denitration control device according to the first aspect, the state quantity of the gas turbine is the number of revolutions of the gas turbine.

A sixth aspect of the present invention is based on the first aspect.
The state quantity of the gas turbine is characterized by the ammonia concentration at the denitration outlet immediately before the ignition of the gas turbine. According to a seventh aspect of the present invention, in the denitration control device according to the first aspect, the predetermined period of time when the minimum opening is limited is a time from the ignition of the gas turbine until the minimum opening limit is released. To do.

According to an eighth aspect of the present invention, in the denitration control device according to the first aspect, the predetermined period of time when the opening is limited to the minimum opening is a fixed time after ignition of the gas turbine. According to a ninth aspect of the present invention, in the denitration control device according to the first aspect, the predetermined period of time when the opening degree is limited to the minimum opening is the time from ignition of the gas turbine to the rated rotation speed. .

According to a tenth aspect of the present invention, in the denitration control device according to the first aspect, during a predetermined period of time when the opening is limited to the minimum opening,
It is characterized in that it is the time from the ignition of the gas turbine to the stop control.

According to an eleventh aspect of the present invention, in the denitration control device according to the first aspect, during a predetermined period of time when the opening is limited to the minimum opening,
It is characterized in that it is the time from the ignition of the gas turbine until the minimum opening restriction is released.

According to a twelfth aspect of the present invention, in the denitration control device according to the first aspect, during a predetermined period of time when the opening is limited to the minimum opening,
It is characterized in that it is the time from the completion of warming up of the gas turbine until the minimum opening limit is released.

According to a thirteenth aspect of the present invention, in the denitration control device according to the first aspect, during a predetermined period of time when the opening is limited to the minimum opening,
It is characterized in that it is a fixed time from the independent point of the gas turbine. A fourteenth aspect of the present invention is characterized in that, in the denitration control device according to the first aspect, a predetermined period of time during which the opening degree is limited to a minimum is a fixed time after the rated rotational speed of the gas turbine is reached.

According to a fifteenth aspect of the present invention, in the denitration control device according to the first aspect, the arithmetic unit is a function generator. A sixteenth aspect of the present invention is characterized in that in the denitration control device according to the first aspect, the arithmetic unit is a fuzzy inference mechanism.

[0024]

In the denitration control device, the fire extinguishing time at the time of ignition of the gas turbine is calculated by the arithmetic unit to determine the minimum opening of the ammonia flow rate adjusting valve by the opening of the ammonia flow rate adjusting valve, thereby limiting the lower limit of the control signal. The contact operates until the minimum opening limit is released from the ignition of the gas turbine, the minimum opening is selected during operation, and the fully closed signal is selected during non-operation. Therefore, from the ignition of the gas turbine until the minimum opening limit is released, the opening of the ammonia flow control valve is held at the minimum opening according to the extinguishing time, and an excessive increase in NOx is prevented, and good control is performed. In addition, the reaction does not proceed so much when the temperature of the catalyst immediately after ignition is low, but most of the ammonia is adsorbed by the catalyst and discharged from the chimney because the amount of ammonia adsorbed on the catalyst is small during the stop. The amount of unreacted ammonia is relatively small. Further, although the amount of ammonia adsorbed on the catalyst changes depending on the length of the stop time, the initial opening of the ammonia flow rate adjusting valve is set to an appropriate opening according to the length of the stop time. This makes it possible to configure a control system that always maintains good control performance even when the temperature of the catalyst at startup is low.

[0025]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows a first embodiment of the present invention (claims 1, 2).
FIG. 16 is a block configuration diagram of a denitration control device according to claim 7 and claim 15).

The present embodiment is different from the conventional example shown in FIG.
In the conventional example, the comparator 44 determines the exhaust gas temperature S13 to track the output of the second PI controller 40 to the fully closed state, but in the present example, the function generator 42 is used.
And a low value limiter 41 and a contact point 43. Until the minimum opening degree limit is released from the ignition of the gas turbine, the contact point 43 controls the minimum opening degree (m) S16 corresponding to the fire extinguishing time (t) S15 by the control signal S12. The point is that it is configured to limit. Since other configurations are the same as those of the conventional example of FIG. 15 which has already been described, the same reference numerals are given to the same portions and the description thereof will be omitted.

In this embodiment, the function of the function generator 42 is
The minimum opening m of the ammonia flow rate adjusting valve 32 is calculated from the fire extinguishing time t in consideration of the effect of the minimum opening m of the ammonia flow rate adjusting valve 32 on NOx and the characteristics of the system. To do.

Next, the operation of this embodiment will be described.
The first adder 3 based on the NOx concentration set value S1 determined by regulation and the NOx concentration detection value S2 discharged from the plant
The NOx concentration deviation signal S3 is obtained by 3, and is input to the first PI controller 34 having a negative gain. The water injection amount signal S4 is input to the FF controller 35 having a negative gain. Next, the output of the first PI controller 34 and the FF controller 35
The output of is added by the second adder 36 and becomes the molar ratio setting signal S5. Further, the ammonia flow rate signal S6 is divided by the gas flow rate S7 in the first divider 37 to become the ammonia concentration signal S8. Further, the ammonia concentration signal S8 is divided by the predicted NOx signal S9 in the second divider 38 to become the molar ratio predicted signal S10. The third adder 39 takes the difference between the molar ratio setting signal S5 and the molar ratio prediction signal S10 and outputs the molar ratio deviation signal S11. The molar ratio deviation signal S11 is
The second PI controller 40 performs a feedback process and outputs the control signal S12 via the low value limiter 41.

Therefore, when the NOx concentration detection value S2 increases, the NOx concentration deviation signal S3 becomes a negative value, and the output of the first PI controller 34 having a negative gain and the molar ratio setting signal S5 increase. Therefore, since the molar ratio deviation signal S11 and the control signal S12 also increase, the NH ₃ flow rate adjusting valve 32 is opened via the actuator 31 and the injection amount of ammonia increases. Further, when the water injection amount signal S4 increases, the output of the FF controller 35 having a negative gain and the molar ratio setting signal S5 decrease. Therefore, since the molar ratio deviation signal S11 and the control signal S12 are also decreased, the NH ₃ flow rate adjusting valve 32 is closed via the actuator 31, and the injection amount of ammonia is decreased.

When the temperature of the catalyst 22 at the time of start-up is below a predetermined temperature determined by the characteristics, the action of the catalyst 22 is not effective and unreacted NH ₃ is discharged from the chimney 4. In order to prevent this, the function generator 42 inputs the fire extinguishing time t and outputs the minimum opening degree m. Immediately after ignition, the contact 43 is in operation, and the minimum opening m and the output of the second PI controller 40 are input to the low limiter 41. Since the amount of NOx generated is small during warming up, the output of the second PI controller 40 is a fully closed signal. Therefore, the low limiter 41
The control signal S12, which is the output of, becomes equal to the minimum opening m, and the opening of the ammonia flow rate adjusting valve is controlled to the minimum opening. At this time, the ammonia injected into the catalyst reacts only slightly because the temperature of the catalyst 22 is low, but the adsorbed ammonia of the catalyst 22 is dissociated during the stop, and the amount of adsorbed ammonia is small, so it is injected. Most of the ammonia is adsorbed and the amount of dissociation is small.

When the gas turbine device 1 enters the speed increasing process,
The amount of NOx generated increases as the rotation speed increases. When the NOx concentration detection value S2 discharged from the plant exceeds the NOx concentration set value S1, the output of the second PI controller 40 gradually increases from the fully closed signal, and finally becomes the output of the low value controller 41, The control signal S12 leaves the minimum opening limit,
The contact 43 is inoperative. After that, the fully closed signal S14 and the output of the second PI controller 40 are input to the low value limiter 41, and the control signal S12 becomes the output of the second PI controller 40. In this way, the emission of NOx is restrained from increasing chaotically and the emission of unreacted NH _{3 from} the chimney 4 is restrained.

As described above, the mole ratio control function based on the predicted NOx signal S9 that includes an error but can be input at high speed and the NOx concentration detection value S2 that has a large delay but is accurate.
By combining the above-mentioned molar ratio setting function with the cascade method, it is possible to perform high-speed and accurate control by extracting the advantages of both. Further, since the molar ratio setting system can back up the error due to the predicted NOx in the molar ratio control system and the characteristic variation due to aging, safe and stable control becomes possible. Further, it is possible to provide a flexible and safe denitration control device that can control the exhausted NOx to a regulated value even when the temperature of the catalyst 22 is low at the time of startup and can suppress the discharge of unreacted NH _{3 from} the chimney 4. it can. As described above, according to the present embodiment, it is possible to provide a denitration control device capable of suppressing fluctuations in exhaust NOx at startup of the combined cycle power plant and performing stable control.

FIG. 2 is a block diagram of the second embodiment (corresponding to claim 3) of the present invention. The denitration control device of the present embodiment differs from the denitration control device of the first embodiment of FIG. 1 in that the minimum opening (m) S16 of the ammonia flow rate adjusting valve, the extinguishing time (t) S15 and the suction of the compressor are performed. Temperature (T1) S17
Since the other configurations are the same as those of the first embodiment, the same reference numerals are given to the same portions and the description thereof will be omitted. Similar to the first embodiment, the present embodiment has an effect that it is possible to provide a denitration control device capable of suppressing an increase in exhaust NOx at startup of the combined cycle power plant and performing stable control.

FIG. 3 is a block diagram of the third embodiment (corresponding to claim 4) of the present invention. The denitration control device of this embodiment is different from the first embodiment of FIG. 1 in that the minimum opening (m) S16 of the ammonia flow rate adjusting valve 32 is set to the extinguishing time (t) S.
In addition to 15, the atmospheric temperature (T2) S18 is set,
Since other configurations are the same, the same reference numerals are given to the same portions and the description thereof will be omitted. Also in this embodiment, similarly to the first embodiment, it is possible to provide a denitration control device capable of suppressing an increase in exhaust NOx at the start of the combined cycle power plant and performing stable control.
The effect is obtained.

FIG. 4 is a block diagram of the fourth embodiment (corresponding to claim 5) of the present invention. The denitration control device of this embodiment is different from that of the first embodiment in that the ammonia flow rate adjusting valve 3
2 is the point that the minimum opening (m) S16 of 2 is a function of the rotational speed (r) S19 of the gas turbine, and other configurations are the same as in the first embodiment, so the same parts are denoted by the same reference numerals. The description will be omitted. Similar to the first embodiment, the present embodiment has an effect that it is possible to provide a denitration control device capable of suppressing an increase in exhaust NOx at startup of the combined cycle power plant and performing stable control.

FIG. 5 is a block diagram of the fifth embodiment (corresponding to claim 6) of the present invention. The denitration control device of this embodiment is different from the first embodiment of FIG. 1 in that the minimum opening (m) S16 of the ammonia flow rate adjusting valve 32 is a function of the ammonia concentration S20 at the denitration outlet immediately before the ignition of the gas turbine. Since other functions are the same as those of the first embodiment, the same parts are designated by the same reference numerals and the description thereof will be omitted. Similar to the first embodiment, the present embodiment has an effect that it is possible to provide a denitration control device capable of suppressing an increase in exhaust NOx at startup of the combined cycle power plant and performing stable control.

FIG. 6 is a block diagram of a sixth embodiment (corresponding to claim 8) of the present invention. The denitration control device of the present embodiment is different from the first embodiment of FIG. 1 in that the minimum opening degree limit is removed from the ignition of the gas turbine during the period when the ammonia flow rate adjusting valve 32 is limited to the minimum opening degree (m) S16. However, the present embodiment uses the contact 46 that operates for a certain period of time after ignition of the gas turbine. Since other configurations are the same as those of the first embodiment, the same parts are designated by the same reference numerals. The description thereof will be omitted. Similar to the first embodiment, the present embodiment has an effect that it is possible to provide a denitration control device capable of suppressing an increase in exhaust NOx at startup of the combined cycle power plant and performing stable control.

FIG. 7 is a block diagram of the seventh embodiment (corresponding to claim 9) of the present invention. The denitration control device of the present embodiment is different from the first embodiment of FIG. 1 in that the minimum opening degree limit is removed from the ignition of the gas turbine during the period when the ammonia flow rate adjusting valve 32 is limited to the minimum opening degree (m) S16. However, the present embodiment uses the contact point 47 that operates for a period of time from the ignition of the gas turbine to the rated rotation speed. Since other configurations are the same as those of the first embodiment, the same portions are used. Are denoted by the same reference numerals and description thereof will be omitted. In this embodiment as well, as in the first embodiment, the emission NO at the start of the combined cycle power plant
It is possible to provide an effect that a denitration control device that suppresses an increase in x and that can perform stable control can be provided.

FIG. 8 is a block diagram of an eighth embodiment (corresponding to claim 10) of the present invention. The denitration control device of the present embodiment is different from the first embodiment of FIG. 1 in that the minimum opening degree limit is removed from the ignition of the gas turbine during the period when the ammonia flow rate adjusting valve 32 is limited to the minimum opening degree (m) S16. However, in this embodiment, the contact 48 that operates for a period from the ignition of the gas turbine to the start of the stop control is used. Since other configurations are the same as those of the first embodiment, Are denoted by the same reference numerals and description thereof will be omitted. This embodiment is also the first
Emission NOx at start-up of combined cycle power plant as in the embodiment
It is possible to provide an effect that it is possible to provide a denitration control device capable of suppressing the increase of the above and performing stable control.

FIG. 9 is a block diagram of the ninth embodiment (corresponding to claim 11) of the present invention. The denitration control device of the present embodiment is different from the first embodiment of FIG. 1 in that the minimum opening degree limit is removed from the ignition of the gas turbine during the period when the ammonia flow rate adjusting valve 32 is limited to the minimum opening degree (m) S16. However, the present embodiment uses the contact 49 that operates for a period of time from the ignition of the gas turbine until the minimum opening limit is released, and the other configurations are the same as those of the first embodiment. The same parts are designated by the same reference numerals and the description thereof will be omitted. Similar to the first embodiment, the present embodiment has an effect that it is possible to provide a denitration control device capable of suppressing an increase in exhaust NOx at startup of the combined cycle power plant and performing stable control.

FIG. 10 shows a tenth embodiment of the present invention (claim 1).
2 is a block configuration diagram of (corresponding to 2). The denitration control device of the present embodiment is different from the first embodiment of FIG. 1 in that the minimum opening degree limit is removed from the ignition of the gas turbine during the period when the ammonia flow rate adjusting valve 32 is limited to the minimum opening degree (m) S16. However, in this embodiment, the contact 50 is used which operates for a period of time from the completion of warming up the gas turbine to the time when the minimum opening limit is released, and the other configurations are the same as those in the first embodiment. The same parts are designated by the same reference numerals and the description thereof will be omitted. Similar to the first embodiment, the present embodiment has an effect that it is possible to provide a denitration control device capable of suppressing an increase in exhaust NOx at startup of the combined cycle power plant and performing stable control.

FIG. 11 shows an eleventh embodiment of the present invention (claim 1).
3 is a block configuration diagram (corresponding to 3). The denitration control device of the present embodiment is different from the first embodiment of FIG. 1 in that the minimum opening degree limit is removed from the ignition of the gas turbine during the period when the ammonia flow rate adjusting valve 32 is limited to the minimum opening degree (m) S16. However, in this embodiment, the contact 51 that operates for a certain time from the self-sustained point of the gas turbine is used. Since the other configurations are the same as those in the first embodiment, the same parts are designated by the same reference numerals. The description is omitted. Similar to the first embodiment, the present embodiment has an effect that it is possible to provide a denitration control device capable of suppressing an increase in exhaust NOx at startup of the combined cycle power plant and performing stable control.

FIG. 12 shows a twelfth embodiment of the present invention (claim 1).
FIG. 4 is a block configuration diagram of 4). The denitration control device of the present embodiment is different from the first embodiment of FIG. 1 in that the minimum opening degree limit is removed from the ignition of the gas turbine during the period when the ammonia flow rate adjusting valve 32 is limited to the minimum opening degree (m) S16. However, the present embodiment uses the contact 52 that operates for a certain period of time after reaching the rated speed of the gas turbine. Since the other configurations are the same as those of the first embodiment, the same parts are the same. The reference numerals are given and the description thereof is omitted. Similar to the first embodiment, the present embodiment has an effect that it is possible to provide a denitration control device capable of suppressing an increase in exhaust NOx at startup of the combined cycle power plant and performing stable control.

FIG. 13 shows a thirteenth embodiment of the present invention (claim 1).
FIG. 6 is a block configuration diagram of (corresponding to 6). The denitration control device of this embodiment is different from the first embodiment of FIG. 1 in that the minimum opening (m) S16 of the ammonia flow rate adjusting valve 32 is realized by a function of the fire extinguishing time t. The fuzzy reasoning mechanism 53 is used to calculate the minimum opening m of the ammonia flow rate control valve from the fire extinguishing time t. Since other configurations are the same as those in the first embodiment, the same parts are designated by the same reference numerals. The description is omitted. Also in this embodiment, similarly to the first embodiment, it is possible to provide a denitration control device capable of suppressing an increase in exhaust NOx at the start of the combined cycle power plant and performing stable control.
The effect is obtained.

[0045]

As described above, according to the present invention,
It is possible to provide a flexible and safe denitration control device that suppresses an increase in exhausted NOx at the time of startup of a complex plant and has little deterioration in control performance with respect to fluctuations in denitration characteristics due to load changes of a gas turbine.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a first embodiment of the present invention.

FIG. 2 is a block configuration diagram of a second embodiment of the present invention.

FIG. 3 is a block configuration diagram of a third embodiment of the present invention.

FIG. 4 is a block configuration diagram of a fourth embodiment of the present invention.

FIG. 5 is a block configuration diagram of a fifth embodiment of the present invention.

FIG. 6 is a block configuration diagram of a sixth embodiment of the present invention.

FIG. 7 is a block configuration diagram of a seventh embodiment of the present invention.

FIG. 8 is a block configuration diagram of an eighth embodiment of the present invention.

FIG. 9 is a block diagram of a ninth embodiment of the present invention.

FIG. 10 is a block configuration diagram of a tenth embodiment of the present invention.

FIG. 11 is a block diagram of an eleventh embodiment of the present invention.

FIG. 12 is a block diagram of a twelfth embodiment of the present invention.

FIG. 13 is a block configuration diagram of a thirteenth embodiment of the present invention.

FIG. 14 is a schematic system diagram of a combined cycle power plant to which the present invention is applied.

FIG. 15 is a block diagram of a conventional denitration control device.

[Explanation of symbols]

1 ... Gas turbine device, 2 ... Exhaust heat recovery boiler device, 3 ...
Steam turbine device, 4 ... Chimney, 5 ... Exhaust gas flow, 6 ... Introduced air, 7 ... Air compressor, 8 ... Fuel system, 9 ... Combustor, 1
0 ... Gas turbine, 11, 19 ... Generator, 12 ... Flue,
13 ... Superheater, 14 ... Evaporator, 15 ... Denitration device, 16 ...
Economizer, 17 ... steam piping, 18 ... steam turbine, 20 ...
Condenser, 21 ... Water supply pipe, 22 ... Catalyst, 23 ... Ammonia injection system, 30 ... Denitration control device, 31 ... Actuator, 32 ... NH ₃ flow control valve, 33, 39, 36 ... Adder, 34, 40 ... PI controller, 35 ... Feed forward controller, 37, 38 ... Divider, 41 ... Low value controller, 4
2 ... Function generator, 43, 46, 47, 48, 49, 5
0, 51, 52 ... contacts, 44 ... comparator, 45 ... contacts, 5
3 ... Fuzzy inference mechanism, S1 ... NOx concentration set value, S2
... NOx concentration detection value, S3 ... NOx concentration deviation signal, S4
... Water injection amount signal, S5 ... Molar ratio setting signal, S6 ... Ammonia flow rate signal, S7 (v) ... Gas flow rate, S8 ... Ammonia concentration signal, S9 ... Predicted NOx signal, S10 ... Molar ratio predicted signal, S11 ... Molar ratio Deviation signal, S12 ... control signal,
S13 ... Exhaust gas temperature detection value, S14 ... Full closing signal, S15
(T) ... Extinguishing time, S16 (m) ... Minimum opening, S17
(T1) ... Compressor suction temperature, S18 (T2) ... Atmospheric temperature, S19 (r) ... Gas turbine rotation speed, S20 ...
Denitration outlet NH ₃ concentration.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B01D 53/74 53/86 ZAB B01D 53/34 129 E 53/36 ZAB (72) Inventor Tetsuya Funatsu 1st Toshiba Town, Fuchu-shi, Tokyo Inside Toshiba Fuchu factory (72) Inventor Toshihiro Yamada 1st Toshiba-cho, Fuchu City Tokyo Fuchu factory

Claims (16)

[Claims] Claim: What is claimed is: 1. A dry denitration device for spraying a mixed ammonia mixed with dilution air onto an exhaust gas of a gas turbine of a combined power generation facility including a gas turbine and a steam turbine, and removing nitrogen oxides by a chemical reaction with a catalyst. In a denitration control device that controls the NOx concentration of exhaust gas by increasing or decreasing the amount, a detector that detects the state quantity of the gas turbine, and a minimum opening degree of the ammonia flow rate adjusting valve based on the detection value detected by the detector And a low value limiting means for controlling the opening of the ammonia flow rate adjusting valve so as not to become the minimum opening or less, depending on the state quantity of the gas turbine at the time of starting the combined cycle power generation facility. A denitration control device that controls the opening of the ammonia flow rate adjusting valve for a predetermined time so that the opening does not fall below the minimum opening. 2. The denitration control device according to claim 1,
The denitration control device, wherein the state quantity of the gas turbine is the extinguishing time at the time of ignition of the gas turbine. 3. The denitration control device according to claim 1, wherein
The denitration control device, wherein the state quantity of the gas turbine is the extinguishing time at the time of ignition of the gas turbine and the suction temperature of the compressor. 4. The denitration control device according to claim 1, wherein
The denitration control device, wherein the state quantity of the gas turbine is the extinguishing time at the time of ignition of the gas turbine and the atmospheric temperature. 5. The denitration control device according to claim 1, wherein
The denitration control device, wherein the state quantity of the gas turbine is the number of revolutions of the gas turbine. 6. The denitration control device according to claim 1, wherein the state quantity of the gas turbine is an ammonia concentration at a denitration outlet immediately before ignition of the gas turbine. 7. The denitration control device according to claim 1,
A denitration control device, characterized in that the predetermined period of time during which the minimum opening is limited is the time from the ignition of the gas turbine until the minimum opening is released. 8. The denitration control device according to claim 1, wherein
A denitration control device characterized in that a predetermined time period during which the opening degree is limited to a minimum is a fixed time after ignition of a gas turbine. 9. The denitration control device according to claim 1, wherein
A denitration control device characterized in that a predetermined period of time when the opening is limited to the minimum opening is a time from ignition of the gas turbine to a rated rotation speed. 10. The denitration control device according to claim 1, wherein the predetermined period of time when the opening degree is limited to the minimum opening is a time from ignition of the gas turbine to start of stop control. 11. The denitration control according to claim 1, wherein the predetermined period of time during which the minimum opening is limited is the time from ignition of the gas turbine until the release of the minimum opening limitation. apparatus. 12. The denitration control device according to claim 1, wherein the predetermined period of time during which the minimum opening is limited is the time from the completion of warming up of the gas turbine until the release of the minimum opening limitation. Control device. 13. The denitration control device according to claim 1, wherein the predetermined period of time during which the opening degree is restricted to a minimum opening is a fixed time from an independent point of the gas turbine. 14. The denitration control device according to claim 1, wherein a predetermined period of time during which the opening degree is limited to a minimum opening is a fixed time after the rated rotation speed of the gas turbine is reached. 15. The denitration control device according to claim 1, wherein the arithmetic unit is a function generator. 16. The denitration control device according to claim 1, wherein the arithmetic unit is a fuzzy inference mechanism.