JP2002186833A - Control method for denitration device in boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method for a denitration device capable of rapidly exhibiting a predetermined denitration performance in the denitration device provided with a denitration catalyst in a boiler. SOLUTION: In the control method for the denitration device 7, a reducing agent having an amount corresponding to a burning amount is fed and is reacted on a denitration catalyst 14 in the boiler 1. At the time of activation of the denitration device 7, until an adsorption amount of the reducing agent on the denitration catalyst 14 reaches to a predetermined amount, a supply amount of the reducing agent is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a denitration apparatus in a boiler for reducing NOx.

[0002]

2. Description of the Related Art In recent years, boilers have been further reduced in NOx.
Is required. As one of the measures, a method of reducing NOx by providing a denitration device in the boiler has been adopted. The denitration device is configured to supply, for example, ammonia as a reducing agent to exhaust gas, and to decompose NOx into nitrogen and water by reacting ammonia with NOx in the exhaust gas in the denitration catalyst. Here, the supply amount of ammonia is determined according to the generation amount of NOx corresponding to the combustion amount of the boiler and the allowable amount of NOx discharged from the boiler. Is an amount that can be completely removed.

[0003] In the denitration apparatus, when the denitration apparatus is started up for the first time, a predetermined denitration performance cannot be exhibited, and the emission of NOx from the boiler may not be reduced. .

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for controlling a denitration apparatus capable of promptly exhibiting a predetermined denitration performance in a denitration apparatus provided with a denitration catalyst in a boiler. That is.

Here, the present inventors have conducted intensive research on a denitration apparatus provided with a denitration catalyst in order to solve the above-mentioned problems.
The following findings were obtained as a result of repeating experiments and the like. This finding means that a predetermined amount of a reducing agent must be adsorbed on the denitration catalyst in order to reduce NOx to a predetermined concentration or less. To further explain the above findings, first, in the denitration catalyst, a reducing agent is adsorbed by the denitration catalyst, and the adsorbed reducing agent and NOx undergo a reduction reaction, whereby NOx is decomposed. Therefore, in order to sufficiently decompose NOx, a predetermined amount of a reducing agent needs to be adsorbed on the denitration catalyst. However, when the denitration apparatus is first started, the reducing agent is not adsorbed on the denitration catalyst at all, or is slightly adsorbed. Therefore, in the denitration apparatus, the adsorbed amount of the reducing agent must be set to the predetermined amount in a short time in order to exhibit the predetermined denitration performance as described above. In view of this point, the inventors have created a control method for solving the above problem based on the above knowledge.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems based on the above-mentioned findings.
The invention according to claim 1 is a method for controlling a denitration device in which a boiler supplies a reducing agent in an amount corresponding to a combustion amount and causes the reducing agent to react in a denitration catalyst. The supply amount of the reducing agent is increased until the adsorption amount of the reducing agent in the denitration catalyst reaches a predetermined amount.

[0007]

Next, an embodiment of the present invention will be described. The present invention is suitably implemented in a denitration apparatus in a boiler.

[0008] The boiler is, for example, a multi-tube boiler. The boiler can has, for example, a combustion chamber inside a row of annular heat transfer tubes and an annular gas passage outside the row of annular heat transfer tubes. And a flue is connected to this gas passage.

In the denitration apparatus, a reducing agent is ejected into a combustion gas from an ejection nozzle provided at an outlet of the gas passage, and the reducing agent reacts with NOx in the combustion gas in a denitration catalyst. NOx is decomposed into nitrogen and water.

As the reducing agent, ammonia itself can be used, or ammonia generated by heating and decomposing urea water can be used. In addition to urea water,
Compounds that decompose by heating or the like to generate ammonia, for example, cyanuric acid, melamine, biuret, and the like can also be used.

The denitration catalyst has a function of accelerating the reduction reaction of NOx by a reducing agent, and is provided in the flue. Therefore, when the combustion gas mixed with the reducing agent flows into the denitration catalyst as exhaust gas at the outlet of the gas passage, NOx is rapidly decomposed into nitrogen and water by the denitration catalyst.

Next, the control method of the present invention will be described. Here, in the following description, when the denitration apparatus is started, as when the denitration apparatus is first started, the reducing agent is not adsorbed to the denitration catalyst at all, or is adsorbed only slightly. There is no time.

In the control method of the present invention, when the denitration apparatus is started, the supply amount of the reducing agent is increased until the adsorption amount of the reducing agent on the denitration catalyst reaches a predetermined amount.

Here, the predetermined amount is an adsorbed amount of a reducing agent necessary for reducing NOx discharged from the boiler to a desired concentration or less.

When the denitration apparatus is started, the supply amount of the reducing agent is made larger than the amount of the reducing agent corresponding to the combustion amount. That is, the supply amount of the reducing agent at this time is set to an amount larger than the amount capable of removing all the NOx generated by the combustion.

Further, the determination that the amount of adsorption of the reducing agent has reached the predetermined amount is made by comparing the NOx concentration between the upstream side and the downstream side of the denitration catalyst. That is, by utilizing the characteristic of the denitration catalyst that the amount of decomposition of NOx rapidly increases when the predetermined amount of the reducing agent is adsorbed, the adsorption amount of the reducing agent reaches the predetermined amount by comparing the NOx concentration. Judge that. Here, the detection of the NOx concentration on the upstream side of the denitration catalyst can be omitted by using, for example, a value obtained by an experiment or calculation in advance.

In the control method of the present invention, when the supply amount of the reducing agent is increased, the reducing agent is supplied in excess of the amount of NOx generated, and this excess amount is adsorbed on the denitration catalyst. Is done. When the adsorption amount of the reducing agent reaches the predetermined amount, the supply amount is reduced to the supply amount corresponding to the combustion amount at that time. Then, since the adsorbed amount of the reducing agent in the denitration catalyst has reached the predetermined amount, predetermined denitration performance can be exhibited.

Here, if the supply amount of the reducing agent is such that all the NOx generated by combustion can be removed, as in the conventional control method, the reducing agent and the NOx do not react with each other. The missing reducing agent is adsorbed on the denitration catalyst. Since the amount of the unreacted reducing agent is small, it takes a long time until the amount of the adsorbed reducing agent reaches the predetermined amount. On the other hand, in the control method of the present invention, when the denitration apparatus is started, the reducing agent is supplied in excess compared to the amount of generated NOx, so that the amount of adsorption of the reducing agent can be increased rapidly, The predetermined amount can be set in time. Therefore, a predetermined denitration performance can be promptly exhibited, and the amount of NOx emission at the time of starting the denitration device can be minimized.

Here, in the control method of the present invention, the determination that the amount of adsorbed reducing agent has reached the predetermined amount is made by comparing the NOx concentration as described above.
It can also be performed by comparing the reducing agent concentration instead of comparing the Ox concentration. The reason is that the denitration catalyst has a characteristic that the larger the amount of adsorption of the reducing agent, the larger the amount of decomposition of NOx, but if the amount of adsorption is too large, the amount of leakage of the reducing agent increases. Here, the detection of the concentration of the reducing agent on the upstream side of the denitration catalyst can be omitted by using, for example, a value calculated from the supply amount of the reducing agent.

The determination that the adsorption amount of the reducing agent has reached the predetermined amount can be made by comparing the NOx concentration and the reducing agent concentration.

In the control method according to the present invention, the determination that the amount of the adsorbed reducing agent has reached the predetermined amount is determined by NO
In addition to comparing the x concentration and the reducing agent concentration, it can be performed based on the integrated value of the combustion amount and the integrated value of the supply amount of the reducing agent. Explaining this case, first, the adsorption amount of the reducing agent in the denitration catalyst can be obtained based on the amount of the reducing agent supplied excessively with respect to the NOx generation amount, and the NOx generation amount depends on the combustion amount. Can be determined based on the Therefore, by comparing the integrated value of the combustion amount with the integrated value of the supply amount of the reducing agent, it is possible to determine that the amount of adsorption of the reducing agent has reached the predetermined amount.

Here, when the supply amount of the reducing agent at the time of starting the denitration apparatus is set in accordance with the combustion amount of the boiler, the integrated value of the combustion amount and the integrated value of the supply amount of the reducing agent are set. Either one can be omitted. The reason is that in this case, one of the supply amount and the combustion amount of the reducing agent can be used to determine the other. Further, when the integrated value of the combustion amount is used to determine that the adsorption amount of the reducing agent has reached the predetermined amount,
Instead of the integrated value of the combustion amount, an integrated value of the combustion time can be used.

Further, in the control method of the present invention,
The determination that the adsorption amount of the reducing agent has reached the predetermined amount can be made based on the elapsed time after the supply amount of the reducing agent is increased. That is, when a predetermined time has elapsed since the supply amount of the reducing agent was increased, it is determined that the adsorption amount of the reducing agent has reached the predetermined amount. As described above, when the determination is made based on the elapsed time, it is preferably applied to a case where the supply amount of the reducing agent at the time of starting the denitration device is set to be constant regardless of the combustion amount of the boiler. it can. In this case, the predetermined time is a time required for the adsorption amount in the denitration catalyst to reach the predetermined amount based on the average value of the combustion amount during the operation of the boiler and the supply amount of the reducing agent. This is the set value.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. First, a denitration apparatus in a boiler embodying the present invention will be described with reference to FIG.
Here, the boiler employs so-called three-position control type combustion control in which the amount of combustion is controlled in three stages of high combustion, low combustion, and standby.

In FIG. 1, the boiler 1 includes an upper header (not shown) and a lower header (not shown). A plurality of heat transfer tubes 2, 2,... Are arranged between these two headers. These heat transfer tubes 2 form an annular heat transfer tube row (reference number omitted) by being arranged in an annular shape between the two headers, and each of the upper end and the lower end of each heat transfer tube 2 is It is connected to the upper header and the lower header, respectively. A burner 3 is attached to an upper portion of the boiler 1, and a combustion chamber 4 is formed inside the annular heat transfer tube row. An annular gas passage 5 is provided outside the annular heat transfer tube row. Further, the gas passage 5 is provided on a side wall of the boiler 1.
The flue 6 which communicates with is connected.

In the boiler 1, the denitration device 7 supplies ammonia as a reducing agent to the outlet of the gas passage 5. That is, the denitration device 7 includes a plurality of ammonia jet nozzles 8, 8,... Provided at the outlet of the gas passage 5. In FIG. 1, six jet nozzles 8 are arranged along the axial direction of the heat transfer tubes 2 so that ammonia is jetted toward the upstream side of the gas passage 5. That is, each of the ejection nozzles 8 is arranged so as to eject ammonia in opposition to the flow of the combustion gas in the gas passage 5.

An ammonia generating means 10 is connected to each of the jet nozzles 8 via an ammonia supply pipe 9. This ammonia generating means 10 is a means for decomposing urea water by heating to generate ammonia,
A urea water tank 12 is connected to the ammonia generating means 10 via a urea water supply pipe 11. The urea water supply pipe 11 is provided with a urea water supply pump 13. Therefore, the urea water supply pump 13 is operated to supply urea water from the urea water tank 12 to the ammonia generation means 10, and the ammonia generation means 10 heats the urea water to continuously convert gaseous ammonia. The ammonia is supplied to the ejection nozzles 8 and ejected from the ejection nozzles 8. Here, the control of the supply amount of ammonia to the combustion gas is performed by controlling the supply amount of urea water by the urea water supply pump 13.

Further, the denitration device 7 includes a denitration catalyst 14 for accelerating the reduction reaction of NOx by ammonia.
The denitration catalyst 14 is provided in the flue 6. Here, the operation of the denitration catalyst 14 will be further described. The denitration catalyst 14 first decomposes NOx into nitrogen and water by adsorbing ammonia and promoting the reduction reaction of NOx by the adsorbed ammonia. Therefore, in order to sufficiently decompose NOx, a predetermined amount of ammonia needs to be adsorbed on the denitration catalyst 14.

Next, a control configuration of the boiler 1 and the denitration device 7 will be described. First, the boiler 1 is provided with a pressure detecting means 15, and the pressure detecting means 15 is configured to detect a steam pressure in the boiler 1. The pressure detecting means 15 and the burner 3 are connected to a controller 17 via signal lines 16, 16, and based on a signal from the pressure detecting means 15, increase the combustion amount of the burner 3. The control is performed in stages. The boiler 1 controls the amount of combustion in three stages of high combustion, low combustion, and standby. When the vapor pressure rises and exceeds a preset first pressure, the boiler 1 shifts from high combustion to low combustion, When the pressure rises further and exceeds a preset second pressure, the process shifts from low combustion to standby. When the steam pressure falls below the second pressure, the combustion shifts from standby to low combustion, and when the steam pressure falls further below the first pressure, the combustion shifts from low combustion to high combustion.

In the denitration device 7, the urea water supply pump 13 is connected to the controller 17 via the signal line 16. Therefore, the urea water supply pump 13 is controlled by the controller 17, and the supply amount of urea water, that is, the supply amount of ammonia, is controlled according to the combustion amount. Here, the supply amount of ammonia is set according to the generation amount of NOx at each combustion amount.

Further, in the denitration apparatus 7, downstream of the denitration catalyst 14, a concentration detecting means 18 for detecting the NOx concentration is provided.
Is connected to the controller 17 via the signal line 16. Then, the supply amount of ammonia is controlled based on the signal from the concentration detecting means 18.

In the above configuration, the burner 3
Is operated, a gas undergoing a combustion reaction, that is, a combustion gas in a flame state is generated in the combustion chamber 4. The combustion reaction of the combustion gas in the flame state is almost completed in the combustion chamber 4 and flows into the gas passage 5. After flowing through the gas passage 5, the combustion gas is discharged to the outside through the flue 6 as exhaust gas.

During operation of the burner 3,
When the urea water supply pump 13 and the ammonia generating means 10 are operated, ammonia is jetted from the jet nozzles 8. This ammonia is mixed with the combustion gas at the outlet of the gas passage 5. At this time, since the ammonia is ejected in the direction opposite to the flow direction of the combustion gas, the mixing of the ammonia and the combustion gas is promoted. Then, when the combustion gas mixed with ammonia passes through the denitration catalyst 14, the NOx reduction reaction by ammonia is promoted by the denitration catalyst 14,
Since Ox is rapidly decomposed into nitrogen and water, NOx in the combustion gas is reduced.

Here, when the denitration apparatus 7 is started, the supply amount of ammonia is controlled as follows.

First, the first embodiment will be described with reference to FIG. Here, the combustion amount in the boiler 1 and the supply amount of ammonia in the denitration device 7 are set as shown in FIG. First, the combustion amount at the time of high combustion is set to the first combustion amount A, and the combustion amount at the time of low combustion is the second combustion amount B which is about half of the first combustion amount A.
, And the combustion amount during standby is set to zero. The supply amount of ammonia at the time of high combustion corresponding to the first combustion amount A is set to the first supply amount C, and the supply amount of ammonia at the time of low combustion corresponding to the second combustion amount B is , The second supply amount D, and the standby ammonia supply amount is set to zero. Therefore, the second supply amount D is about half of the first supply amount C. Here, in the following description, it is assumed that ammonia is not adsorbed on the denitration catalyst 14 before the operation of the denitration device 7 is started. In the first embodiment, ammonia is adsorbed to the denitration catalyst 14 until a predetermined amount is reached. The predetermined amount is determined based on the amount of ammonia adsorbed necessary to reduce NOx to a desired concentration or less. This is the set value.

After the operation of the boiler 1 is started and the denitration device 7 is started, the NOx on the downstream side of the denitration catalyst 14 is detected by the concentration detecting means 18.
Detect x concentration. Then, based on the detected value of the NOx concentration, the amount of ammonia adsorbed on the denitration catalyst 14 is monitored.

When the boiler 1 shifts from standby to low combustion, the combustion amount switches from zero to the second combustion amount B. Further, in the denitration device 7, the supply amount of ammonia is switched from zero to the third supply amount E. The third supply amount E is a value larger than the first supply amount C.

Then, during the low combustion period, the ammonia which has not reacted with NOx is adsorbed on the denitration catalyst 14, and
The amount of adsorption starts to increase. That is, the amount of ammonia corresponding to the difference between the third supply amount E and the second supply amount D is adsorbed on the denitration catalyst 14.
Thereafter, when the combustion amount shifts from low combustion to high combustion, an amount of ammonia corresponding to the difference between the third supply amount E and the first supply amount C is adsorbed on the denitration catalyst 14. . Therefore, in the denitration catalyst 14, the amount of adsorption increases in a short time, and in accordance with the increase in the amount of adsorption, the reduction reaction of NOx in the denitration catalyst 14 is promoted, and the NOx concentration to be discharged rapidly decreases. .

When it is detected based on the detection value of the concentration detecting means 18 that the amount of adsorbed ammonia has reached the predetermined amount, the supply amount of ammonia is determined according to the combustion amount at that time. It switches to the first supply amount C or the second supply amount D. For example, as shown in FIG. 2, if the amount of adsorption of ammonia reaches the predetermined amount during high combustion, the supply amount switches from the third supply amount E to the first supply amount C. At this time, the denitration catalyst 14
Has been adsorbed to the predetermined amount,
As shown by the solid line in FIG. 2, the NOx concentration from the boiler 1 is greatly reduced.

Thereafter, the switching of the supply amount of ammonia is performed according to the switching of the combustion amount. That is, when the combustion amount is switched to the second combustion amount B, the supply amount is switched to the second supply amount D, and when the combustion amount is switched to the first combustion amount A, the supply amount is It switches to the first supply amount C.

Here, in the conventional control method, even when the denitration device 7 is first started, ammonia is supplied in such an amount that all the NOx generated by combustion can be removed. That is, in the conventional control method, ammonia is supplied at the supply amounts C and D corresponding to the combustion amounts A and B, respectively. In this case, since all of the ammonia and NOx do not react,
The unreacted ammonia is adsorbed by the denitration catalyst 14, and the amount of adsorption increases. However, since ammonia that has not reacted with NOx is very small, it takes a long time until the adsorption amount reaches the predetermined amount. Therefore, when the denitration apparatus 7 is started, as shown by the two-dot chain line in FIG.
The Ox concentration also increases.

On the other hand, in the control method of the first embodiment, the supply amount of ammonia at the time of startup is set to the third supply amount E which is larger than the supply amounts C and D.
Even when the denitration device 7 is first started, the adsorption amount of ammonia on the denitration catalyst 14 can be set to the predetermined amount in a short time. Therefore, the predetermined denitration performance can be promptly exhibited, the NOx concentration can be rapidly reduced, and the NOx emission can be minimized.

In the first embodiment, after the amount of adsorption reaches the predetermined amount, the amount is switched to the first supply amount A or the second supply amount B according to the combustion amount. Therefore, after the amount of adsorption reaches the predetermined amount, the amount of adsorption of ammonia hardly increases. Therefore, it is possible to prevent ammonia from being discharged from the denitration catalyst 14. The reason for this is that if the amount of ammonia adsorbed by the denitration catalyst 14 becomes too large,
This is because it has a characteristic that the concentration of ammonia leaking to the downstream side of the air increases.

Next, a second embodiment will be described with reference to FIG. The second embodiment is an embodiment in which the determination that the amount of adsorption of ammonia has reached the predetermined amount is made based on the integrated value of the combustion amount and the integrated value of the supply amount of ammonia. In the following description of the second embodiment, control while increasing the supply amount of ammonia will be described, and control after the amount of adsorption of ammonia reaches the predetermined amount will be the same as in the first embodiment. Since it is the same, it is omitted.

First, in the second embodiment, when the denitration device 7 is started, the supply amount of ammonia is increased as follows. That is, at the time of the first combustion amount A, a fourth supply amount F that is a predetermined multiple of the first supply amount C is used. The supply amount is set to G. Therefore, since the supply amounts F and G can be obtained based on the combustion amounts A and B, the integrated value of the ammonia supply amount is:
It can be obtained based on the integrated value of the combustion amount.

Further, in the second embodiment, the integrated value of the combustion amount is obtained from the integrated value of the combustion time. Here, when performing the integration of the combustion time, since the boiler 1 employs a three-position control type combustion control,
The combustion time is integrated based on the combustion amount during high combustion. That is, since the second combustion amount B is set to about half of the first combustion amount A, the combustion time at the second combustion amount B is integrated with a half value.

In the second embodiment, the boiler 1
Is started, and when the denitration device 7 is started, the accumulation of the combustion time is started. When the boiler 1 shifts from standby to low combustion, the combustion amount switches from zero to the second combustion amount B. Further, in the denitration device 7, the supply amount of ammonia switches from zero to the fifth supply amount G. Then, during this low combustion, ammonia that has not reacted with NOx is adsorbed by the denitration catalyst 14, and the amount of adsorption starts to increase. That is,
An amount of ammonia corresponding to the difference between the fifth supply amount G and the second supply amount D is adsorbed on the denitration catalyst 14. After that, when the combustion amount shifts from low combustion to high combustion, an amount of ammonia corresponding to the difference between the fourth supply amount F and the first supply amount C is adsorbed on the denitration catalyst 14.

Then, after the denitration device 7 is started and before the integrated value of the combustion time reaches the predetermined integrated time,
The supply amount of ammonia switches to the fourth supply amount F or the fifth supply amount G according to the combustion amount at that time. Here, the predetermined integration time is a value set based on a combustion time required until the amount of adsorbed ammonia reaches the predetermined amount when the supply amount of ammonia is increased.

Therefore, since the supply amount of ammonia is increased until the integrated value of the combustion time reaches the predetermined integrated time, the adsorption amount of ammonia in the denitration catalyst 14 rapidly increases, and this adsorption amount is increased. In accordance with the increase, the reduction reaction of NOx in the denitration catalyst 14 is promoted,
The exhausted NOx concentration sharply decreases. Therefore, also in the second embodiment, the predetermined denitration performance can be promptly exerted, the NOx concentration can be rapidly reduced, and the NOx emission can be minimized.

When the integrated value of the combustion time reaches the predetermined integrated time, the supply amount of ammonia switches to the first supply amount C or the second supply amount D according to the combustion amount at that time. . For example, as shown in FIG. 3, if the predetermined integration time has been reached during high combustion, the supply amount of ammonia switches from the fourth supply amount F to the first supply amount C.

Next, a third embodiment will be described with reference to FIG. The third embodiment is an embodiment in which the determination that the amount of adsorbed ammonia has reached the predetermined amount is made based on the time elapsed since the start of the denitration device 7. In the following description of the third embodiment, control while increasing the supply amount of ammonia is described,
The control after the amount of adsorbed ammonia reaches the above-mentioned predetermined amount is the same as in the first embodiment, and is omitted.

In the third embodiment, when the denitration apparatus 7 is started by starting the operation of the boiler 1, the measurement of the elapsed time is started. At this time, as in the first embodiment, the supply amount of ammonia switches from zero to the third supply amount E, and during this low combustion,
Ammonia corresponding to the difference between the third supply amount E and the second supply amount D is adsorbed on the denitration catalyst 14. Thereafter, when the combustion shifts to high combustion, as in the first embodiment, the amount of ammonia corresponding to the difference between the first supply amount C and the third supply amount E is adsorbed on the denitration catalyst 14. Is done.

The ammonia supply amount is maintained at the third supply amount E until the elapsed time from the activation of the denitration device 7 reaches the predetermined time H. Therefore, the amount of adsorption in the denitration catalyst 14 rapidly increases, and as the amount of adsorption increases, the amount of N 2 in the denitration catalyst 14 increases.
The reduction reaction of Ox is promoted, and the amount of exhausted NOx decreases sharply. Here, the predetermined time H is a time required for the adsorption amount of ammonia to reach the predetermined amount based on the average value of the combustion amount during operation of the boiler 1 and the third supply amount E. This is the set value.

Therefore, until the elapsed time reaches the predetermined time H, the supply amount of ammonia is increased, so that the adsorption amount of ammonia is rapidly increased, and the denitration catalyst is increased in accordance with the increase in the adsorption amount. The NOx reduction reaction at 14 is promoted, and the concentration of exhausted NOx sharply decreases. Therefore, also in the third embodiment, the predetermined denitration performance can be promptly exhibited, the NOx concentration can be promptly reduced, and the NOx emission can be minimized.

When it is determined that the elapsed time since the start of the denitration device 7 has reached the predetermined time H and the amount of adsorbed ammonia has reached the predetermined amount, the supply amount of ammonia is determined at that time. The first supply amount C according to the combustion amount of
Alternatively, it is switched to the second supply amount D. For example, FIG.
As shown in (2), when the integrated value of the combustion time reaches the predetermined integrated time during high combustion, the supply amount of ammonia switches from the third supply amount E to the first supply amount C.

[0056]

According to the present invention, when the denitration apparatus is started, a predetermined denitration performance can be promptly exhibited, so that the amount of NOx emission can be minimized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a denitration device in a boiler embodying the present invention.

FIG. 2 is an explanatory diagram showing a time chart of control contents and a change in NOx concentration in the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a time chart of control contents and a change in NOx concentration in a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a time chart of control contents and a change in NOx concentration in a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler 7 Denitration device 14 Denitration catalyst

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Koichi Masuda 7th Horie-cho, Matsuyama-shi, Ehime Miura Research Institute, Inc. (72) Inventor Ishizakisaki Nobuyuki 7th Horie-cho, Matsuyama-shi, Ehime Miura Kogyo Co., Ltd. (72) Inventor Yukihiro Isshiki 7th Horie-cho, Matsuyama-shi, Ehime Miura Kogyo Co., Ltd. F-term (reference) 4D048 AA06 AB02 AC04 CA03 DA01 DA10 EA04

Claims (1)

[Claims] 1. A method for controlling a denitration device 7 in which a reducing agent is supplied to a boiler 1 in an amount corresponding to a combustion amount, and the reducing agent is reacted in a denitration catalyst 14. A method for controlling a denitration apparatus in a boiler, comprising increasing the supply amount of a reducing agent until the amount of adsorption of the reducing agent in the denitration catalyst 14 reaches a predetermined amount.