JP2009279490A - Ammonia-injecting system and ammonia-injecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ammonia-injecting system and an ammonia-injecting method capable of appropriately adjusting the amount of ammonia injected to exhaust gas. <P>SOLUTION: The ammonia-injecting system for injecting ammonia to a draft 4 for causing the exhaust gas produced by combustion of fuel to flow therethrough includes: an injection device 13 which injects ammonia to the draft 4 and adjusts the amount of injection of ammonia; and a controller 16 which calculates the rate of injection of ammonia by using the flow rate of fuel, the amount of the exhaust gas exhausted by combustion of the fuel, the concentration of sulfur oxide in the exhaust gas and a set value which is set beforehand, and controls the amount of injection of ammonia by means of the injection device 13 based on the rate of injection of ammonia. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ammonia injection system and an ammonia injection method for injecting ammonia into exhaust gas.

Some facilities, such as power plants, use heavy oil as fuel. When heavy oil burns in a boiler installed at a power plant or the like, sulfur in the heavy oil becomes sulfurous acid gas (SO ₂ ), and part of the sulfurous acid gas becomes sulfuric anhydride (SO ₃ ). Furthermore, anhydrous sulfuric acid reacts with moisture in the exhaust gas to become sulfuric acid (H ₂ SO ₄ ). In this way, sulfuric acid is contained in the exhaust gas, but sulfuric acid causes air pollution and corrodes the flue installed between the power plant boiler and the chimney.

For this purpose, ammonia is injected into the exhaust gas to convert sulfuric acid to ammonium sulfide ((NH ₄ ) ₂ SO ₄ ), and thereafter the ammonium sulfide is recovered from the exhaust gas with a dust collector. There are various processing apparatuses that treat sulfuric anhydride by injecting ammonia into the exhaust gas (see, for example, Patent Document 1). This processing apparatus effectively produces ammonium sulfide by injecting fine particles together with ammonia into the exhaust gas.
JP 2004-181292 A

  However, the conventional processing apparatus has the following problems. This processing apparatus injects fine particles together with ammonia into the exhaust gas, but it is necessary to adjust the amount of ammonia to be injected according to the amount of exhaust gas. That is, when the amount of exhaust gas increases or when the flow rate of fuel increases, the exhaust gas contains sulfuric acid unless the amount of ammonia to be injected is increased. On the other hand, in the case of a reduction in exhaust gas, if the amount of ammonia to be injected is not reduced, waste of ammonia will increase. However, in the conventional processing apparatus, it is necessary to adjust the amount of ammonia to be injected by a valve provided in the ammonia injection path, and appropriately adjust the amount of ammonia to be injected according to the change of exhaust gas. Is difficult.

  An object of the present invention is to provide an ammonia injection system and an ammonia injection method that can solve the above-described problems and appropriately adjust the amount of ammonia injected into exhaust gas.

  In order to solve the above-mentioned problem, the invention of claim 1 is an ammonia injection system for injecting ammonia into a flue through which exhaust gas generated by fuel combustion flows, and injecting ammonia into the flue. An injection device that adjusts the injection amount of ammonia, the flow rate of the fuel, the amount of exhaust gas discharged by combustion of the fuel, the concentration of sulfur oxide in the exhaust gas, and a preset set value An ammonia injection rate, and a control device that controls the amount of ammonia injected by the injection device based on the ammonia injection rate.

  In the first aspect of the present invention, a set value is set in advance for the control device. In such a state, the injection device injects ammonia into the flue and adjusts the injection amount of this ammonia. The control device calculates the ammonia injection rate by using the flow rate of the fuel, the amount of exhaust gas emitted by the combustion of the fuel, the concentration of sulfur oxide in the exhaust gas, and the set value. The amount of ammonia injected by the injection device is controlled based on the injection rate.

  The invention according to claim 2 is the ammonia injection system according to claim 1, comprising a measuring device for measuring the flow rate of the fuel and the concentration of sulfur oxide in the exhaust gas discharged by the combustion of the fuel, The control device receives the flow rate of fuel and the concentration of sulfur oxide in the exhaust gas from each of the measurement devices, and calculates the amount of exhaust gas from the flow rate of the fuel.

  According to a third aspect of the present invention, in the ammonia injection system according to the first aspect, the flow rate of the fuel, the amount of exhaust gas discharged by combustion of the fuel, and the concentration of sulfur oxide in the exhaust gas are measured. The control device receives the flow rate of fuel, the amount of exhaust gas, and the concentration of sulfur oxide in the exhaust gas from each of the measurement devices.

  According to a fourth aspect of the present invention, in the ammonia injection system according to any one of the first to third aspects, the set values set in the control device include a sulfuric acid conversion rate in exhaust gas, an excess ratio of ammonia, It is a conversion factor of ammonia.

  According to a fifth aspect of the present invention, there is provided an ammonia injection method for injecting ammonia into a flue through which exhaust gas generated by fuel combustion flows, and a flow rate of fuel and an amount of exhaust gas discharged by combustion of the fuel, The ammonia injection rate is calculated using the concentration of sulfur oxide in the exhaust gas and a preset value, and the ammonia injection rate is controlled based on the ammonia injection rate. This is an ammonia injection method.

  According to the first and fifth aspects of the present invention, since the control device controls the injection device based on the flow rate of fuel, the amount of exhaust gas, and the concentration of sulfur oxide, the flow rate of fuel, the amount of exhaust gas, and the amount of sulfur oxide Even if the concentration changes and the amount of sulfuric acid in the exhaust gas changes, the amount of ammonia injected can be optimized. Further, after a set value is input to the control device, the ammonia injection amount can be automatically controlled by this control device.

  According to the invention of claim 2, since the control device calculates the amount of exhaust gas from the flow rate of fuel, a device for measuring the amount of exhaust gas becomes unnecessary, and the system configuration can be simplified.

  According to the invention of claim 3, since the control device obtains the amount of exhaust gas from the measuring device, the ammonia injection rate can be accurately calculated. As a result, the amount of ammonia injected can be further optimized.

  According to the invention of claim 4, the set values are the sulfuric acid conversion rate in the exhaust gas, the excess ratio of ammonia, and the conversion factor of ammonia, such as the amount of fuel burned, such as sulfuric acid in the exhaust gas. Therefore, it is not necessary to frequently set a setting value for the control device.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, a case where the present invention is applied to a power plant will be described as an example.

(Embodiment 1)
An ammonia injection system according to this embodiment is shown in FIG. This ammonia injection system is used in a power generator. The power generation device generates power by rotating a turbine (not shown) by steam generated by a boiler 1 using fuel oil as fuel, and includes a denitration device 2 and a dust collector 3 in the flue 4. The introduced exhaust gas GA is discharged from the chimney 5. The denitration device 2 removes nitrogen oxides from the exhaust gas GA, and the dust collector 3 removes soot from the exhaust gas GA. The ammonia injection system used in such a power generation apparatus includes a fuel flow meter 11, a SOX (sox: sulfur oxide) meter 12, an injection device 13, an ammonia tank 14, a valve device 15, and a control device 16.

The fuel flow meter 11 detects the flow rate of the fuel sent to the boiler 1 and sends a fuel flow signal representing the fuel flow rate to the control device 16. The SOX meter 12 measures the concentration of sulfur oxide (SO _X ) contained in the exhaust gas GA from the boiler 1 and sends a concentration measurement signal representing the concentration of sulfur oxide to the control device 16. The ammonia tank 14 is a tank for storing ammonia. The valve device 15 includes a valve (not shown) that adjusts the flow rate of ammonia from the ammonia tank 14. The valve device 15 controls the opening degree of the valve by a control signal from the control device 16, adjusts the flow rate of ammonia from the ammonia tank 14, and sends it to the injection device 13. The injection device 13 vaporizes the ammonia from the valve device 15 and injects the ammonia into the exhaust gas GA flowing through the flue 4. As a result, the injection device 13 converts the sulfuric acid in the exhaust gas GA to ammonium sulfide. This ammonium sulfide is recovered by the dust collector 3.

  The control device 16 generates a control signal based on the fuel flow rate signal and the concentration measurement signal, and sends this control signal to the valve device 15. The configuration of the control device 16 is shown in FIG. The control device 16 in FIG. 2 includes a processing unit 16A, a storage unit 16B, an input unit 16C, an input interface 16D, a display unit 16E, and an output interface 16F.

The input unit 16C is an input device such as a keyboard and a mouse operated by a person in charge, and various instructions and numerical values are input to the input unit 16C. In particular, in this embodiment, the SO ₃ conversion rate, excess rate, and ammonia conversion factor necessary for generating the control signal are input. The SO ₃ conversion rate represents the rate of conversion from SO ₂ to SO ₃ . The SO ₃ conversion rate is a value within a certain range as shown in FIG. The excess rate is the following value. When ammonia is injected, ammonia that is unreacted with sulfuric acid is generated. The excess ratio represents the ratio of the amount of ammonia actually supplied to the amount of ammonia required to convert all sulfuric acid into ammonium sulfide. This excess rate is a substantially constant value. The ammonia conversion factor is for calculating the amount of ammonia.
Ammonia conversion factor = 2 × 17 / 22.4
Is obtained by the following formula. here,
Numerical value 2: NH ₄ / SO ₄ reaction molar ratio (NH ₄ ) ₂ SO ₄
Numerical value 17: The molecular volume of ammonia is a gas volume in a standard state of 22.4: 1 mol of the numerical value. Such an ammonia conversion coefficient is a constant value.

The input interface 16D receives the fuel flow rate signal from the fuel flow meter 11 and the concentration measurement signal from the SOX meter 12, and sends these signals to the processing unit 16A. The display unit 16E is a display device such as a liquid crystal display, and displays various data and the like under the control of the processing unit 16A. In particular, in this embodiment, the SO ₃ conversion rate, excess rate, ammonia conversion coefficient input to the input unit 16C, the fuel flow rate signal received by the input interface 16D, the concentration measurement signal, and the like are displayed. The output interface 16F sends a control signal to the valve device 15 under the control of the processing unit 16A. The storage unit 16B temporarily stores various data. The storage unit 16B stores an injection control process for controlling the injection amount of ammonia.

The processing unit 16A performs the injection control process stored in the storage unit 16B. When the injection control process is started, the processing unit 16A receives the SO ₃ conversion rate, excess rate, and ammonia conversion coefficient as set values from the input unit 16C as shown in FIG. 4 (step S1). After step S1, the processing unit 16A receives the fuel flow rate signal and the concentration measurement signal from the input interface 16D as measurement values (step S2). After step S2, the processing unit 16A calculates an exhaust gas amount based on the fuel flow rate represented by the fuel flow rate signal (step S3). The fuel flow rate and the exhaust gas amount are in a correlation. After step S3, the processing unit 16A calculates the SO ₃ conversion rate, excess rate, and ammonia conversion coefficient received from the input unit 16C, the SO _X concentration represented by the concentration measurement signal, and the fuel flow rate represented by the fuel flow signal. Based on the amount of exhaust gas
G = A * B * C * D * E / F
The ammonia injection rate is calculated using the injection rate calculation formula (step S4). here,
A: SO _X concentration in the exhaust gas GA B: SO ₃ conversion C: exhaust gas amount (m ³ N / H)
D: Excess ratio E: Ammonia conversion factor F: Fuel flow rate (kl / H)
G: Ammonia injection rate (kg / kl)
It is.

An example of these values is shown below.
A: SO _X concentration in the exhaust gas GA 980/10 ⁶ (980 ppm)
B: SO ₃ conversion ratio: 2.5 / 100 (2.5%)
C: Exhaust gas amount ... 322,661 (m ³ N / H)
D: Excess ratio ... 1.12
E: Ammonia conversion coefficient 2 × 17 / 22.4 (each numerical value is as described above)
F: Fuel flow rate 38.4 (kl / H)
G: Ammonia injection rate: 0.35 (kg / kl)
In the unit of fuel flow rate and ammonia injection rate, “l” represents liter.

  After step S4, the processing unit 16A generates a control signal for controlling the opening degree of the valve included in the valve device 15 from the calculated ammonia injection rate, that is, a control signal for increasing the opening degree of the valve when the ammonia injection rate increases. Generate (step S5). The processing unit 16A sends this control signal to the valve device 15 (step S6). After step S6, the processing unit 16A measures a predetermined time (step S7), and then determines whether or not the input of the end of the injection control process is in the input unit 16C (step S8). If there is no process end input, the control device 16 returns the process to step S1, and ends the process when the process end input is received.

  Thus, the processing unit 16A controls the opening of the valve of the valve device 15 by the control signal.

Next, an ammonia injection method using the ammonia injection system of this embodiment will be described. In the input unit 16C of the control device 16, the SO ₃ conversion rate, excess rate, and ammonia conversion coefficient are input in advance as set values.

  On the other hand, the fuel flow meter 11 detects the flow rate of the fuel flowing into the boiler 1 and sends a fuel flow signal to the control device 16. The boiler 1 burns fuel to generate electric power, and the exhaust gas GA generated by the combustion of the fuel is discharged from the flue 4 through the denitration device 2, the injection device 13, and the dust collector 3. The SOX meter 12 measures the concentration of sulfur oxide contained in the exhaust gas GA and sends a sulfur oxide concentration measurement signal to the control device 16.

  When the control device 16 receives the fuel flow rate signal and the concentration measurement signal, the processing unit 16A of the control device 16 performs an injection control process to generate a control signal, and sends this control signal to the valve device 15. The valve device 15 controls the opening degree of the valve by a control signal, adjusts the amount of ammonia from the ammonia tank 14, and sends it to the injection device 13. The injection device 13 injects ammonia into the exhaust gas GA that has passed through the denitration device 2 to change the sulfuric acid into ammonium sulfide. Thereafter, the dust collector 3 collects soot such as ammonium sulfide in the exhaust gas GA.

Thus, according to this embodiment, the injection control process is performed even if the SO _X concentration in the exhaust gas GA, the amount of the exhaust gas GA, and the flow rate of the fuel change, and the amount of sulfuric acid in the exhaust gas GA changes. Thus, the injection amount of ammonia can be optimized. Further, according to this embodiment, after the set value is input, the injection amount of ammonia can be automatically controlled, and labor saving can be achieved. Further, according to this embodiment, it is possible to appropriately adjust the amount of ammonia to be injected into the exhaust gas GA without requiring modification to the flue 4 and the injection device 13. Furthermore, according to this embodiment, since all the sulfuric acid is processed by the injection device 13, it is possible to prevent the dust collecting device 3 from being corroded by sulfuric acid and being deactivated.

(Embodiment 2)
An ammonia injection system according to this embodiment is shown in FIG. This ammonia injection system is used in a power generator similar to that in the first embodiment. In this embodiment, components that are the same as or the same as those of the ammonia injection system of FIG. 1 described above are denoted by the same reference numerals, and description thereof is omitted. The ammonia injection system of FIG. 5 further includes an exhaust gas amount measuring device 21 with respect to the ammonia injection system of the first embodiment.

  The exhaust gas amount measuring device 21 is installed in the flue 4, measures the amount of exhaust gas GA flowing through the flue 4, and outputs an exhaust gas amount measurement signal representing the amount of exhaust gas that is the amount of exhaust gas GA to the control device 16. Send to.

  In the control device 16, as shown in FIG. 6, the input interface 16 </ b> D receives the exhaust gas amount measurement signal from the exhaust gas amount measurement device 21 together with other signals. In FIG. 6, components that are the same as or the same as those in FIG. 2 described above are denoted by the same reference numerals, and description thereof is omitted.

When the injection control process is started, the processing unit 16A receives the SO ₃ conversion rate, excess rate, and ammonia conversion coefficient as set values from the input unit 16C as shown in FIG. 7 (step S11). After step S11, the processing unit 16A receives the fuel flow rate signal, the exhaust gas amount measurement signal, and the concentration measurement signal as measurement values from the input interface 16D (step S12). After step S12, the processing unit 16A receives the SO ₃ conversion rate, excess rate, and ammonia conversion coefficient received from the input unit 16C, the SO _X concentration indicated by the concentration measurement signal, and the exhaust gas amount indicated by the exhaust gas amount measurement signal. Then, based on the fuel flow rate represented by the fuel flow rate signal, the ammonia injection rate is calculated using the injection rate calculation formula similar to that of the first embodiment (step S13). Since the following steps S14 to S17 are the same as steps S5 to S8 of the first embodiment, description of steps S14 to S17 is omitted.

Thus, by this embodiment, as in the first embodiment, the amount of SO _X concentration and exhaust gas GA in the exhaust gas GA, flow rate of the fuel is changed, it changes the amount of sulfuric acid in the exhaust gas GA However, the injection amount of ammonia can be optimized by performing the injection control process. Further, similarly to the first embodiment, after the set value is input, the ammonia injection amount can be automatically controlled, and labor saving can be achieved. Moreover, since all sulfuric acid is processed with the injection apparatus 13 similarly to Embodiment 1, it can prevent that the dust collector 3 corrodes with sulfuric acid, and becomes a function stop. Furthermore, according to this embodiment, since the amount of exhaust gas GA is measured by the exhaust gas amount measuring device 21, the processing unit 16A can accurately calculate the ammonia injection rate. As a result, the amount of ammonia injected can be further optimized.

(Embodiment 3)
An ammonia injection system according to this embodiment is shown in FIG. This ammonia injection system is used in a power generator similar to that in the first embodiment. In this embodiment, components that are the same as or the same as those of the ammonia injection system of FIG. 1 described above are denoted by the same reference numerals, and description thereof is omitted. The ammonia injection system of FIG. 8 has a configuration that does not use the SOX meter 12 of the first embodiment.

In the control device 16, as shown in FIG. 9, the input interface 16 </ b> D receives only the fuel flow signal from the fuel flow meter 11. In FIG. 9, components that are the same as or the same as those in FIG. 2 described above are denoted by the same reference numerals, and description thereof is omitted. The sulfur content of the fuel is input to the input unit 16C together with the SO ₃ conversion rate, excess rate, and ammonia conversion coefficient.

When the injection control process is started, the processing unit 16A receives the SO ₃ conversion rate, excess rate, ammonia conversion coefficient, and fuel sulfur content as set values from the input unit 16C (step S31). After step S31, the processing unit 16A receives the fuel flow rate signal as a measurement value from the input interface 16D (step S32). After step S32, the processing unit 16A calculates the exhaust gas amount based on the fuel flow rate indicated by the fuel flow rate signal, and calculates the SO _X concentration from the sulfur content of the fuel (step S33). After step S33, the processing unit 16A obtains the SO ₃ conversion rate, excess rate, and ammonia conversion coefficient received from the input unit 16C, the fuel flow rate represented by the fuel flow rate signal, the calculated exhaust gas amount, and the SO _X concentration. Based on this, the ammonia injection rate is calculated using the same injection rate calculation formula as in the first embodiment (step S33). Since the following steps S34 to S38 are the same as steps S4 to S8 of the first embodiment, description of steps S34 to S38 is omitted.

Thus, by this embodiment, as in the first embodiment, the amount of SO _X concentration and exhaust gas GA in the exhaust gas GA, flow rate of the fuel is changed, it changes the amount of sulfuric acid in the exhaust gas GA However, the injection amount of ammonia can be optimized by performing the injection control process. Further, similarly to the first embodiment, after the set value is input, the ammonia injection amount can be automatically controlled, and labor saving can be achieved. Moreover, since all sulfuric acid is processed with the injection apparatus 13 similarly to Embodiment 1, it can prevent that the dust collector 3 corrodes with sulfuric acid, and becomes a function stop. Furthermore, according to this embodiment, since the SOX meter 12 is not used, the system can be simplified. In the second embodiment, the system can be configured without using the SOX meter 12 as in the third embodiment.

  The embodiment of the present invention has been described in detail above, but the specific configuration is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention, Included in the invention. For example, the unit of time measurement in step S7 can be as follows: 1 second, 1 minute, 1 hour, 1 day, 1 round, 1 month, etc.

It is a block diagram which shows the ammonia injection system by Embodiment 1 of this invention. It is a block diagram which shows an example of a control apparatus. It is a diagram representing the SO ₃ conversion. It is a flowchart showing an injection | pouring control process. It is a block diagram which shows the ammonia injection system by Embodiment 2 of this invention. 6 is a block diagram illustrating an example of a control device according to Embodiment 2. FIG. 10 is a flowchart showing an injection control process according to the second embodiment. It is a block diagram which shows the ammonia injection system by Embodiment 3 of this invention. FIG. 10 is a block diagram illustrating an example of a control device according to a third embodiment. 10 is a flowchart illustrating an injection control process according to the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Boiler 2 Denitration device 3 Dust collector 4 Flue 5 Chimney 11 Fuel flow meter 12 SOX meter 13 Injection device 14 Ammonia tank 15 Valve device 16 Control device 16A Processing part 16B Storage part 16C Input part 16D Input interface 16E Display part 16F Output Interface 21 Exhaust gas measuring device

Claims (5)

In the ammonia injection system that injects ammonia into the flue that flows exhaust gas generated by fuel combustion,
An injection device for injecting ammonia into the flue and adjusting the injection amount of the ammonia;
The ammonia injection rate is calculated using the flow rate of the fuel, the amount of exhaust gas emitted by the combustion of the fuel, the concentration of sulfur oxide in the exhaust gas, and the preset set value. A control device for controlling the amount of ammonia injected by the injection device based on the injection rate;
An ammonia injection system comprising: Each has a measuring device for measuring the flow rate of the fuel and the concentration of sulfur oxide in the exhaust gas discharged by the combustion of this fuel,
The said control apparatus receives the flow volume of a fuel and the density | concentration of the sulfur oxide in exhaust gas from each said measuring apparatus, The amount of exhaust gas is calculated from the flow volume of this fuel, It is characterized by the above-mentioned. Ammonia injection system. Each equipped with a measuring device for measuring the flow rate of fuel, the amount of exhaust gas emitted by combustion of this fuel, and the concentration of sulfur oxides in this exhaust gas,
2. The ammonia injection system according to claim 1, wherein the control device receives a flow rate of fuel, an amount of exhaust gas, and a concentration of sulfur oxide in the exhaust gas from each of the measurement devices.   4. The ammonia according to claim 1, wherein the set value set in the control device is a sulfuric acid conversion rate in exhaust gas, an excess ratio of ammonia, and a conversion factor of this ammonia. 5. Injection system. In the ammonia injection method of injecting ammonia into the flue that flows exhaust gas generated by fuel combustion,
Calculate the ammonia injection rate using the flow rate of the fuel, the amount of exhaust gas emitted by the combustion of this fuel, the concentration of sulfur oxide in this exhaust gas, and the preset set value,
Control the amount of ammonia injected based on this ammonia injection rate,
A method for injecting ammonia.

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