JP5677787B2 - Denitration control device and denitration control method - Google Patents

Description

The present invention relates to a denitration control device and a denitration control method for reducing the NOx concentration in exhaust gas discharged from a waste treatment furnace.

Waste treatment facilities that treat waste, such as garbage, remove nitrogen oxides (NOx) contained in the exhaust gas discharged from waste treatment furnaces such as melting furnaces and incinerators, and regulate the NOx concentration. An exhaust gas treatment facility is provided for the following. In the exhaust gas treatment facility, ammonia (NH ₃ ) is injected into the exhaust gas and chemically reacted with NOx, whereby NOx is decomposed into nitrogen and water to reduce the NOx concentration. At that time, if ammonia is excessively injected, it is discharged as leaked ammonia to the outside, which causes a problem. On the other hand, if the ammonia injection amount is insufficient, the NOx concentration in the exhaust gas exceeds the regulation value.

For this reason, various denitration control methods for injecting an appropriate ammonia amount corresponding to the NOx amount to be processed have been proposed. For example, in Patent Document 1, since the NOx concentration at the inlet of the NOx removal catalyst device is proportional to the amount of exhaust gas passing through the NOx removal catalyst device, an amount of ammonia necessary for the decomposition of NOx determined based on the amount of exhaust gas is blown into the smoke outlet NOx. A method for controlling the concentration is disclosed.

In Patent Document 2, a process for obtaining a deviation NOx flow rate corresponding to a deviation amount between the NOx flow rate before processing and the target NOx flow rate, and a deviation amount between the NOx concentration after processing and the target NOx concentration are handled. Determining the NOx concentration correction amount, determining the NOx removal rate correction amount corresponding to the deviation between the actual NOx removal rate and the target NOx removal rate, and the ammonia concentration and target in the exhaust gas after treatment The deviation NOx flow rate was corrected based on the step of obtaining the ammonia concentration correction amount corresponding to the deviation amount from the ammonia concentration and the correction amount of at least one of the NOx concentration correction amount, the denitration rate correction amount, and the ammonia concentration correction amount. A step of obtaining a corrected NO _X flow rate, and a step of obtaining a target ammonia flow rate value based on the corrected NOx flow rate and controlling a flow rate of ammonia injected into the pre-treatment exhaust gas. A denitration control method is disclosed.

Furthermore, in Patent Document 3, based on the NOx concentration in the exhaust gas obtained by the NOx analyzer installed on the outlet side of the denitration reaction tank (denitration catalyst device), the amount of ammonia in the denitration reaction tank always has an ammonia adsorption capacity. A method of ON / OFF control of the ammonia injection amount so as to be maintained within the maximum value is disclosed.

JP 2003-164725 A JP 2005-169331 A Japanese Patent Laid-Open No. 55-1858

However, the control method of Patent Document 1 does not take into account the time delay (several minutes to several tens of minutes) in the denitration process, and therefore has a problem that the control accuracy is poor because it cannot follow the rapid fluctuation of the NOx concentration.
On the other hand, although the control method of Patent Document 2 includes a dead time correction unit that takes into account the delay time in the denitration process, there is a problem that the effect is not disclosed and the control system is complicated.
In the control method of Patent Document 3, it is not necessary to consider the time delay in the denitration process because the adsorbed ammonia serves as a buffer, but when the NOx concentration rises to the set value, the solenoid valve is opened and ammonia is injected for a predetermined time. Since the solenoid valve is closed after the lapse of time, if the NOx concentration fluctuates rapidly when the amount of adsorbed ammonia decreases, the sudden fluctuation of the NOx concentration cannot be processed, and the peak of the NOx concentration exceeds the regulation value. There is a fear.

The present invention has been made in view of such circumstances, and it is not necessary to consider a large time delay of the denitration process, and even if the NOx amount fluctuates rapidly, the NOx concentration at the smoke outlet can be suppressed to a regulation value or less. An object is to provide a control device and a denitration control method.

The present inventors have found that the peak of nitrogen oxide (NOx) concentration at the smoke outlet from which exhaust gas is discharged depends on the amount of residual ammonia remaining in the denitration catalyst device. FIG. 10A shows the time history change of the NOx concentration at the NOx removal catalyst device inlet and the smoke outlet in the conventional exhaust gas treatment facility, and FIG. 10B shows the ammonia injection amount at that time and the residual ammonia amount remaining in the NOx removal catalyst device. This shows the change in time history. Here, the residual ammonia amount remaining in the denitration catalyst device is an integrated value of (ammonia injection amount (kg / h) −ammonia consumption amount (kg / h)). From this figure, it was found that if ammonia remained sufficiently in the denitration catalyst device, the NOx concentration at the smoke outlet became low and no peak was generated.

The invention of the present application is based on the above knowledge, and the first invention is that ammonia is blown into a denitration catalyst device provided in an exhaust gas treatment facility for treating exhaust gas discharged from a waste treatment furnace so that NOx in the exhaust gas is reduced. In the denitration control device that reduces the NOx concentration at the smoke outlet that discharges the exhaust gas by decomposing, the NOx amount in the exhaust gas at the inlet of the denitration catalyst device is calculated, and the NOx amount is calculated based on the calculated NOx amount. The means for calculating the ammonia injection amount to be blown into the denitration catalyst device and the value obtained by subtracting the ammonia consumption amount per unit time from the ammonia injection amount per unit time are integrated, and the calculated value remains in the denitration catalyst device. the residual ammonia amount, the residual ammonia amount is constant range the maximum variation of the amount of NOx can be decomposed into nitrogen and water It is characterized in that it comprises a means for correcting the ammonia blown amount.
However, the maximum fluctuation amount of the NOx amount is determined by measuring the NOx concentration with a NOx analyzer installed at the inlet of the denitration catalyst device during a trial operation of the exhaust gas treatment facility, and obtaining the average value. Obtained by multiplying the fluctuation rate of the exhaust gas flow rate assumed in the treatment facility.

In addition, the second invention discharges the exhaust gas by decomposing NOx in the exhaust gas by injecting ammonia into a denitration catalyst device provided in an exhaust gas treatment facility for treating the exhaust gas discharged from the waste treatment furnace. In the denitration control method for reducing the NOx concentration of the smoke outlet at the smoke outlet, the amount of ammonia blown into the denitration catalyst device is calculated based on the calculated amount of NOx by calculating the amount of NOx in the exhaust gas at the inlet of the denitration catalyst device calculating a integrates the value obtained by subtracting the ammonia consumption per unit time from the ammonia blown amount per unit time, and the residual ammonia amount remaining the calculated value in the denitration catalyst unit, the residual ammonia amount to but correcting the ammonia blown amount such that the predetermined range capable of degrading the maximum variation of the amount of NOx to nitrogen and water It is characterized in that it comprises a step.
However, the maximum fluctuation amount of the NOx amount is determined by measuring the NOx concentration with a NOx analyzer installed at the inlet of the denitration catalyst device during a trial operation of the exhaust gas treatment facility, and obtaining the average value. Obtained by multiplying the fluctuation rate of the exhaust gas flow rate assumed in the treatment facility.

In the first and second inventions, by controlling the amount of residual ammonia remaining in the denitration catalyst device to be within a certain range in which the maximum fluctuation amount of the NOx amount at the inlet of the denitration catalyst device can be decomposed into nitrogen and water , It is possible to treat with the remaining ammonia in the denitration catalyst device against a rapid fluctuation of the NOx amount (decompose NOx into nitrogen and water to reduce the NOx concentration). As a result, the peak of the smoke outlet NOx concentration is suppressed, and the smoke outlet NOx concentration can always be kept below the regulation value.

In the denitration control device according to the first aspect of the present invention, when the NOx concentration of the smoke outlet exceeds a set value, the ammonia blowing amount is forcibly increased for a certain time and the calculated value of the residual ammonia amount is corrected. It is suitable to provide.

Further, in the denitration control method according to the second invention, when the NOx concentration at the smoke outlet exceeds a set value, the ammonia blowing amount is forcibly increased for a certain time and the calculated value of the residual ammonia amount is corrected. It is suitable to provide.

The calculated value of the residual ammonia amount is between the actual residual ammonia amount due to instrument errors of each measuring instrument (exhaust gas flow meter, NOx analyzer, ammonia flow meter) and performance changes due to aging of the denitration catalyst device. Although there is a concern that the generated error may accumulate, the above configuration can eliminate the accumulated error.

Further, in the denitration control device according to the first aspect of the present invention, at the denitration catalyst device inlet based on the time average value of the control output proportional to the deviation between the measured value of the smoke outlet NOx concentration and the target value of the smoke outlet NOx concentration. A means for correcting the NOx amount may be provided.

Further, in the denitration control method according to the second aspect of the present invention, based on the time average value of the control output proportional to the deviation between the measured value of the smoke outlet NOx concentration and the target value of the smoke outlet NOx concentration, A step of correcting the NOx amount may be provided.

With the above configuration, the calculated value of the NOx amount at the inlet of the denitration catalyst device can be brought close to the actual NOx amount, and wasteful blowing of ammonia (injecting ammonia even though the NOx concentration is low) is prevented. Can do.

In the present invention, the amount of residual ammonia remaining in the denitration catalyst device is calculated, and the ammonia injection amount is adjusted so that the residual ammonia amount falls within a certain range in which the maximum variation of the NOx amount at the inlet of the denitration catalyst device can be decomposed into nitrogen and water. By controlling, it is possible to suppress the NOx concentration at the smoke outlet to below the regulation value even if the NOx amount fluctuates rapidly without considering a large time delay of the denitration process.

It is a schematic diagram which shows an example of a structure of waste gas processing equipment. 1 is a block diagram of a denitration control device according to an embodiment of the present invention. It is a graph which shows an example of the relationship between a control output and a 1st correction coefficient. It is a graph which shows an example of the relationship between NOx amount and ammonia blowing amount. It is a graph which shows an example of the relationship between residual ammonia amount and a 2nd correction coefficient. It is a graph which shows an example of the relationship between the amount of exhaust gas, and the amount of ammonia injection. It is a graph which shows an example of the relationship between control output and ammonia injection amount. (A) is a NOx concentration at the smoke outlet, and (B) is a graph showing an example of a time history change of each ammonia blowing amount. It is a graph of the test result which compared the denitration control method which concerns on one embodiment of this invention, and the conventional denitration control method about the reduction effect of NOx concentration in waste gas. (A) shows the NOx concentration at the denitration catalyst device inlet and smoke outlet in the conventional exhaust gas treatment facility, and (B) shows the time history changes of the ammonia blowing amount and the remaining ammonia amount remaining in the denitration catalyst device at that time. It is a graph of a test result.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.

FIG. 1 is a schematic diagram illustrating an example of an exhaust gas treatment facility provided in a waste treatment facility. Exhaust gas discharged from a waste treatment furnace (not shown) such as a melting furnace or an incinerator is sent to the boiler 11 for heat recovery, cooled to a predetermined temperature by the exhaust gas temperature controller 12, and filtered dust collection. The dust is removed by the vessel 13. The dust-removed exhaust gas is sent to the denitration catalyst device 15 by the induction fan 14, denitrated in the denitration catalyst device 15, and then discharged from the chimney 16.

In the denitration catalyst device 15, nitrogen oxide (NOx) contained in the exhaust gas reacts with ammonia (NH ₃ ) adsorbed on the catalyst layer disposed inside the device and decomposes into nitrogen and water.
The end of the ammonia pipe 21 is connected to the exhaust gas pipe 17 provided between the induction fan 14 and the denitration catalyst device 15, and ammonia is supplied from the ammonia supply device 18 provided at the start of the ammonia pipe 21. Ammonia fed through the pipe line 21 is supplied into the denitration catalyst device 15 by being blown into the exhaust gas pipe line 17.

In addition, a control valve 20 is provided on the path of the ammonia pipe 21. By controlling the degree of opening and closing of the control valve 20 by a denitration control apparatus 10 (shown in FIG. 2) described later, the amount of ammonia injected can be controlled. Adjusted. The denitration control device 10 is installed on the NOx analyzer 22 installed between the induction ventilator 14 and the denitration catalyst device 15, the NOx analyzer 23 and exhaust gas flow meter 24 installed in the chimney 16, and the ammonia pipe 21. By calculating the amount of ammonia blown based on each output of the ammonia flow meter 19 and controlling the degree of opening and closing of the control valve 20, the smoke outlet NOx concentration at the smoke outlet is reduced.

FIG. 2 shows a block diagram of a denitration control device 10 according to one embodiment of the present invention. The main functions of the present denitration control device 10 are as follows.
(1) Ammonia injection amount calculating means (process): Ammonia injected into the denitration catalyst device 15 based on the calculated NOx amount by calculating the NOx amount in the exhaust gas at the inlet of the denitration catalyst device 15 (NOx amount calculation unit 35) The blowing amount is calculated (ammonia blowing amount calculation unit 40).
(2) First correcting means (step): calculating a time average value of the control output (smoke outlet NOx concentration adjusting unit 32) proportional to the deviation between the measured value of the smoke outlet NOx concentration and the target value of the smoke outlet NOx concentration (Control output tendency calculating unit 36), and the calculated value of the NOx amount is corrected (first correction coefficient calculating unit 37) based on the time average value.
(3) Second correction means (step): The amount of residual ammonia remaining in the denitration catalyst device 15 is calculated (residual ammonia amount calculation unit 41), and the amount of residual ammonia is within a range where the maximum fluctuation amount of NOx can be processed. The calculated value of the ammonia injection amount is corrected so as to be constant (second correction coefficient calculation unit 43). The maximum fluctuation range of the NOx amount is determined by measuring the NOx concentration by the NOx analyzer 22 installed at the inlet of the denitration catalyst device 15 during the trial operation of the waste treatment facility, and obtaining the average value. Is obtained by multiplying the fluctuation rate of the exhaust gas flow rate (the gas flow rate at the inlet of the denitration catalyst device 15) assumed in (1).
(4) Ammonia forced increase means (process): When the smoke outlet NOx concentration exceeds a set value (for example, 80% of the regulation value), the ammonia blowing amount is forcibly increased for a certain time (ammonia forced increase portion 45). At the same time, the calculated value of the residual ammonia amount is corrected (residual ammonia amount calculation unit 41).

Hereinafter, the configuration and operation of the denitration control device 10 will be described in detail.
The NOx concentration calculator 31 at the inlet of the NOx removal catalyst device calculates the NOx concentration at the inlet of the NOx removal catalyst device 15 based on the output of the NOx analyzer 22 installed between the induction fan 14 and the NOx removal catalyst device 15. Further, the exhaust gas flow rate calculation unit 30 calculates the exhaust gas flow rate based on the output of the exhaust gas flow meter 24 installed in the chimney 16. The NOx concentration calculated at the NOx concentration calculating unit 31 at the NOx removal catalyst device and the exhaust gas flow rate calculated at the exhaust gas flow rate calculating unit 30 are multiplied by the NOx amount calculating unit 35 to obtain the NOx amount at the inlet of the NOx removal catalyst device 15. Is calculated.

On the other hand, the smoke outlet NOx concentration adjustment unit 32 calculates a control output (operation output) based on the output of the NOx analyzer 23 installed in the chimney 16. Specifically, the control output proportional to the deviation between the measured value of the smoke outlet NOx concentration at the smoke outlet obtained by the NOx analyzer 23 and the target value of the smoke outlet NOx concentration input using an input device (not shown). Is calculated in the range of 0 to 100%.
Then, the control output tendency calculation unit 36 calculates the time average value of the control output (for example, the average value of the control output per hour), and based on the time average value of the control output, the NOx amount calculation unit 35 described above. A first correction coefficient calculation unit 37 calculates a first correction coefficient for correcting the calculated NOx amount at the inlet of the denitration catalyst device 15. The first correction coefficient calculation unit 37 calculates the first correction coefficient based on the relationship between the control output and the first correction coefficient as shown in FIG. That is, when the control output is b ₁ % or more and b ₂ % or less, the first correction coefficient is set to 1, and when the control output is less than b ₁ %, the first correction coefficient is set to 1 according to the magnitude of the control output. When the control output is more than b ₂ %, for example, the first correction coefficient is set to 1 according to the magnitude of the control output. (For example, when the control output is 100%, the first correction coefficient is 1.1.) Here, for example, 20% to 30% as _{b 1,} a _{b 2} may be a 70-80%, for example.

The first correction unit 38 corrects the NOx amount by multiplying the NOx amount calculated by the NOx amount calculation unit 35 by the first correction coefficient calculated by the first correction coefficient calculation unit 37. That is, when the smoke outlet NOx concentration increases, correction for increasing the NOx amount is performed, and when the smoke outlet NOx concentration decreases, correction for decreasing the NOx amount is performed.

The ammonia blowing amount calculation unit 40 calculates the ammonia blowing amount based on the relationship between the NOx amount and the ammonia blowing amount as shown in FIG. In the example of FIG. 4, when the NOx amount is equal to or less than c (Nm ³ / h), the ammonia injection amount is set to a constant value and the minimum ammonia injection amount is set. On the other hand, when c (Nm ³ / h) is exceeded, the ammonia blowing amount is increased according to the amount of NOx. Here, the c example, when the maximum NOx amount is 18 Nm ³ / h, can be converted into their 10% of 1.8 Nm ³ / h.
The ammonia blowing amount is calculated by multiplying the NOx amount by the ammonia equivalent ratio (0.7 to 1.3). This equivalence ratio is determined by measuring and verifying the NOx amount and the NOx removal rate of the NOx removal catalyst device 15 in the trial operation of the waste treatment facility.

Next, means (steps) for correcting the ammonia injection amount so that the residual ammonia amount remaining in the denitration catalyst device 15 is constant will be described.
The ammonia flow rate calculation unit 33 calculates the ammonia flow rate supplied from the ammonia supply device 18 based on the output of the ammonia flow meter 19 installed on the ammonia pipe 21.
The residual ammonia amount calculation unit 41 calculates the residual ammonia amount remaining in the denitration catalyst device 15 based on the ammonia flow rate calculated by the ammonia flow rate calculation unit 33 and the ammonia injection amount calculated by the ammonia injection amount calculation unit 40. Is done. Specifically, the value obtained by subtracting the ammonia consumption amount per unit time from the ammonia blowing amount per unit time is integrated, and the integrated value is used as the residual ammonia amount. At that time, the ammonia flow rate calculated by the ammonia flow rate calculation unit 33 is used as the ammonia injection amount per unit time, and the ammonia injection amount calculated by the ammonia injection amount calculation unit 40 is used as the ammonia consumption amount per unit time.

When the residual ammonia amount is calculated, the calculation of the second correction coefficient for correcting the ammonia injection amount so that the residual ammonia amount is constant within a range where the maximum fluctuation amount of the assumed NOx amount can be processed is the second correction. This is performed in the coefficient calculation unit 43.
The second correction coefficient calculation unit 43 calculates the second correction coefficient based on the relationship between the residual ammonia amount and the second correction coefficient as shown in FIG. That is, when the residual ammonia amount is d ₁ kg or more and d ₂ kg or less (the range in which the maximum fluctuation amount of the NOx amount can be processed), the second correction coefficient is set to 1, and when the residual ammonia amount is less than d ₁ kg, When the second correction coefficient is made larger than 1 in accordance with the decrease in the ammonia amount (for example, the second correction coefficient is 1.1 when the residual ammonia amount is 0 kg) and the residual ammonia amount exceeds d ₂ kg The second correction coefficient is made smaller than 1 as the residual ammonia amount increases (for example, the second correction coefficient is set to 0.9 when the residual ammonia amount is d ₃ kg). Here, d ₁ can be, for example, −4 to −2 kg, d ₂ can be, for example, 5 to 6 kg, and d ₃ can be, for example, 9 to 11 kg.

The second correction unit 42 corrects the ammonia injection amount by multiplying the ammonia injection amount calculated by the ammonia injection amount calculation unit 40 by the second correction coefficient calculated by the second correction coefficient calculation unit 43. That is, when the residual ammonia amount decreases, the ammonia injection amount is increased, and when the residual ammonia amount increases, the ammonia injection amount is decreased so that the residual ammonia amount becomes constant within a range where the maximum fluctuation amount of the NOx amount can be processed. Ammonia injection amount is corrected.

Further, in the present denitration control device 10, the FF correction unit 34 that corrects the ammonia injection amount based on the exhaust gas flow rate calculated by the exhaust gas flow rate calculation unit 30, and the control output calculated by the smoke outlet NOx concentration adjustment unit 32. And an FB correction unit 39 that corrects the ammonia injection amount based on the FB correction unit 39.
The FF correction unit 34 calculates the correction amount of the ammonia injection amount based on the relationship between the exhaust gas amount and the ammonia injection amount as shown in FIG. 6, and the FB correction unit 39 controls the control output and ammonia as shown in FIG. The correction amount of the ammonia injection amount is calculated based on the relationship with the injection amount. Incidentally, in the example of FIG. 6, when the amount of exhaust gas is e (Nm ³ / h) or less, the ammonia injection amount is set to a constant value, and when it exceeds e (Nm ³ / h), the ammonia is increased according to the amount of exhaust gas. The amount of blowing is increased. In the example of FIG. 7, the control output and the ammonia injection amount are in a directly proportional relationship. Here, the e example, if the maximum exhaust gas flow rate and 40000Nm ³ / h, can be converted into their 10% of 4000 Nm ³ / h.

The ammonia injection amount corrected in the second correction unit 42 is added together with each correction amount of the ammonia injection amount calculated by the FF correction unit 34 and the FB correction unit 39 in the addition unit 44, and the target value of the ammonia injection amount is obtained. Is done.

The ammonia flow rate adjustment unit 47 generates a control signal proportional to the deviation between the measured value of the ammonia injection amount (ammonia flow rate) obtained by the ammonia flow rate calculation unit 33 and the target value of the ammonia injection amount calculated by the addition unit 44. Output and control the degree of opening and closing of the control valve 20.

The above-described series of operations is a normal operation in the denitration control apparatus 10, but the ammonia forced increase means is an operation when the smoke outlet NOx concentration exceeds the set value due to an accumulated error between the calculated value and the measured value. (Process) will be described.
In the ammonia forced increase unit 45, the smoke outlet NOx concentration obtained through the smoke outlet NOx concentration adjusting unit 32 is set to a value lower than the upper limit (regulated value) (for example, 80% of the regulated value). ) (See time t _{1 in} FIG. 8A), the amount of ammonia injected is forcibly increased (for example, if the average amount of ammonia injected is 3.5 kg / h, it is 7 kg / h, twice that amount). the blown.) Referring _{t 1} time (FIG. 8 (B)). Then, the lower limit chimney outlet NOx concentration (e.g., 40% of the value of the regulation value) below (Fig. 8 (see t ₂ time A)), a timer (not shown) is operated, t ₂ time from a predetermined time ( for example, 5 minutes) after the elapse of, stops the increase of the ammonia blown amount reference t ₂ time (FIG. 8 (B)).
Also in conjunction with the operation, the residual ammonia amount calculating unit 41, a residual ammonia amount when the chimney outlet NOx concentration below the lower limit (t ₂ time) and reset (corrected) to zero, and the actual calculated value The deviation from the value is eliminated.

A switching unit 46 that switches between the output of the addition unit 44 and the output of the ammonia forced increase unit 45 is provided in the preceding stage of the ammonia flow rate adjustment unit 47. In the switching unit 46, the output of the addition unit 44 is selected during normal times, but when the ammonia injection amount is forcibly increased, the output of the ammonia forced increase unit 45 is selected during that time.

FIG. 9 shows the test results comparing the denitration control method according to an embodiment of the present invention and the conventional denitration control method with respect to the NOx concentration reduction effect in the exhaust gas. From the figure, it can be seen that according to the denitration control method according to the present embodiment, the smoke outlet NOx concentration is controlled to the target value of 20 ppm or less, and the peak exceeding 20 ppm is suppressed. In addition, it can be seen that the smoke outlet NOx concentration does not become around 0 ppm, and the waste blowing is improved.

Although one embodiment of the present invention has been described above, the present invention is not limited to the configuration described in the above-described embodiment, and is within the scope of matters described in the claims. Other possible embodiments and modifications are also included. For example, in the above embodiment, the NOx concentration at the inlet of the denitration catalyst device is obtained using the NOx analyzer installed between the induction fan and the denitration catalyst device, but the control output time proportional to the NOx concentration at the smoke outlet is obtained. Since the NOx amount is corrected based on the average value, the NOx analyzer may not be installed between the induction fan and the denitration catalyst device, and the NOx concentration at the inlet of the denitration catalyst device may be a fixed value. In the above embodiment, the smoke outlet NOx concentration adjusting unit and the ammonia flow rate adjusting unit use P control that makes the control output proportional to the deviation, but in addition, PID control that is proportional to the integral and derivative of the deviation may be used. .

10: Denitration control device, 11: Boiler, 12: Exhaust gas temperature controller, 13: Filtration type dust collector, 14: Induction fan, 15: Denitration catalyst device, 16: Chimney, 17: Exhaust gas line, 18: Ammonia Supply device, 19: ammonia flow meter, 20: control valve, 21: ammonia pipe, 22, 23: NOx analyzer, 24: exhaust gas flow meter, 30: exhaust gas flow rate calculation unit, 31: NOx concentration calculation at denitration catalyst device inlet Unit: 32: smoke outlet NOx concentration adjusting unit, 33: ammonia flow rate calculating unit, 34: FF correcting unit, 35: NOx amount calculating unit, 36: control output tendency calculating unit, 37: first correction coefficient calculating unit, 38: First correction unit, 39: FB correction unit, 40: ammonia injection amount calculation unit, 41: residual ammonia amount calculation unit, 42: second correction unit, 43: second correction coefficient calculation unit, 44: addition unit, 45: Strong ammonia Bulking unit, 46: switch unit, 47: ammonia flow rate regulator

Claims (6)

A smoke outlet for discharging the exhaust gas by decomposing nitrogen oxide (NOx) in the exhaust gas by injecting ammonia into a denitration catalyst device provided in an exhaust gas treatment facility for treating the exhaust gas discharged from the waste treatment furnace In a denitration control device that reduces the NOx concentration at the smoke outlet in
Means for calculating the amount of NOx in the exhaust gas at the inlet of the denitration catalyst device, calculating the amount of ammonia blown into the denitration catalyst device based on the calculated amount of NOx, and unit time from the amount of ammonia blown per unit time The value obtained by subtracting the amount of ammonia consumed per unit is integrated, and the calculated value is used as the amount of residual ammonia remaining in the denitration catalyst device. The amount of residual ammonia is constant so that the maximum fluctuation of the NOx amount can be decomposed into nitrogen and water. A denitration control apparatus comprising: means for correcting the ammonia injection amount so as to be in a range .
However, the maximum fluctuation amount of the NOx amount is determined by measuring the NOx concentration with a NOx analyzer installed at the inlet of the denitration catalyst device during a trial operation of the exhaust gas treatment facility, and obtaining the average value. Obtained by multiplying the fluctuation rate of the exhaust gas flow rate assumed in the treatment facility. 2. The denitration control apparatus according to claim 1, further comprising means for forcibly increasing the ammonia injection amount for a predetermined time and correcting the calculated value of the residual ammonia amount when the NOx concentration at the smoke outlet exceeds a set value. A denitration control device. 3. The NOx removal control apparatus according to claim 1, wherein the NOx amount is corrected based on a time average value of control output proportional to a deviation between a measured value of the smoke outlet NOx concentration and a target value of the smoke outlet NOx concentration. A denitration control device comprising means. A smoke outlet for discharging the exhaust gas by decomposing nitrogen oxide (NOx) in the exhaust gas by injecting ammonia into a denitration catalyst device provided in an exhaust gas treatment facility for treating the exhaust gas discharged from the waste treatment furnace In the denitration control method for reducing the NOx concentration at the smoke outlet in
Calculating the amount of NOx in exhaust gas at the inlet of the denitration catalyst device, calculating the amount of ammonia blown into the denitration catalyst device based on the calculated amount of NOx, and unit time from the amount of ammonia blown per unit time The value obtained by subtracting the amount of ammonia consumed per unit is integrated, and the calculated value is used as the amount of residual ammonia remaining in the denitration catalyst device. The amount of residual ammonia is constant so that the maximum fluctuation of the amount of NOx can be decomposed into nitrogen and water. And a step of correcting the ammonia injection amount so as to be in a range .
However, the maximum fluctuation amount of the NOx amount is determined by measuring the NOx concentration with a NOx analyzer installed at the inlet of the denitration catalyst device during a trial operation of the exhaust gas treatment facility, and obtaining the average value. Obtained by multiplying the fluctuation rate of the exhaust gas flow rate assumed in the treatment facility. 5. The denitration control method according to claim 4, further comprising a step of forcibly increasing the ammonia injection amount for a predetermined time and correcting the calculated value of the residual ammonia amount when the smoke outlet NOx concentration exceeds a set value. A denitration control method. 6. The denitration control method according to claim 4 or 5, wherein the NOx amount is corrected based on a time average value of a control output proportional to a deviation between a measured value of the smoke outlet NOx concentration and a target value of the smoke outlet NOx concentration. A denitration control method comprising a step.

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