JP5448783B2 - Denitration apparatus and denitration method - Google Patents

Description

  The present invention relates to a denitration apparatus and a denitration method.

  In business and industrial coal-fired power plants, NOx is contained in the combustion exhaust gas discharged from coal-fired boilers, and a denitration device is used to remove this nitrogen oxide. It has been known. Conventionally, a catalyst for removing nitrogen oxides by a chemical reaction has been used in a denitration apparatus. A catalyst is provided in a direction that allows combustion exhaust gas to pass therethrough, and a gas obtained by vaporizing ammonia water and combustion exhaust gas are mixed. It is decomposed into harmless nitrogen and water. The catalyst usually has a honeycomb structure, and when the combustion exhaust gas contains dust, the catalyst may be partially or totally blocked. Therefore, a technique for detecting the blockage has been proposed. For example, Patent Document 1 discloses a technique for detecting the amount of deposits on a catalyst layer using sound waves.

JP-A-3-109925

  However, in the above-mentioned Patent Document 1, in order to measure the attenuation amount of the sound wave in the propagation path of the radio wave transmitted / received by the sound wave transmitter / receiver arranged at the position facing the periphery of the deposit on the catalyst layer, it is somewhat on the catalyst layer. If the deposit is not in a deposited state, the sound wave attenuation cannot be detected, and the clogging of the catalyst cannot be detected.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a denitration apparatus and a denitration method that can accurately detect the clogging of a catalyst.

In order to solve the above problems, the present invention employs the following means.
The present invention is a denitration apparatus comprising a catalyst honeycomb layer that introduces combustion exhaust gas into a can and removes nitrogen oxides in the combustion exhaust gas by a chemical reaction with a reducing agent such as ammonia sprayed at the can inlet. In the can, the catalyst honeycomb layer disposed in a plurality of stages at a predetermined interval with respect to the flow direction of the combustion exhaust gas, and a sound wave transmitting unit and a sound wave receiving unit disposed with the catalyst honeycomb layer interposed therebetween, a sound wave the wave transmitting means for transmitting said passed through the catalyst honeycomb layer detects the attenuation of the sound waves based on the sound waves received by the wave receiving means, the clogging of the catalyst honeycomb layer based on the attenuation There is provided a denitration apparatus comprising attenuation detection means for detecting.

According to such a configuration, the sonic wave transmitting means and the sonic wave receiving means arranged with the catalyst honeycomb layers arranged in a plurality of stages at a predetermined interval with respect to the flow direction of the combustion exhaust gas transmit from the sonic wave sending means. When the generated sound wave passes through the catalyst honeycomb layer and is received by the sound wave receiving means, attenuation of the sound wave is detected from the transmitted sound wave and the received sound wave, and the catalyst honeycomb layer is blocked based on the sound wave attenuation. Is detected.
As described above, since the blockage is detected based on the attenuation of the sound wave passing through the catalyst honeycomb layer, when the attenuation amount of the sound wave is larger than the attenuation when the catalyst honeycomb layer is not blocked, the catalyst honeycomb Detect that the layer is occluded. Thereby, it is before the end stage symptom that dust is deposited on the catalyst honeycomb layer, and the blockage generated in the catalyst honeycomb layer can be easily detected even in the initial stage. Moreover, since the blockage state can be grasped according to the amount of attenuation, the number of prepared honeycombs for replacement can be estimated.

The sound wave receiving means of the denitration apparatus may receive sound waves transmitted from the sound wave transmitting means provided at a plurality of different positions and passing through the common catalyst honeycomb layer.
Since there are multiple sound waves received through a common catalyst honeycomb layer, the presence or absence of blockage of the common catalyst honeycomb layer through which multiple sound waves have passed can be determined based on multiple information, improving the accuracy of detecting the blockage Can be made.

A reference example of the present invention is a denitration equipped with a catalyst honeycomb layer that introduces combustion exhaust gas into a can and removes nitrogen oxides in the combustion exhaust gas by chemical reaction with a reducing agent such as ammonia sprayed at the can inlet. In the apparatus, the catalyst honeycomb layer disposed in a plurality of stages at a predetermined interval in the combustion exhaust gas flow direction and a space formed between the stages of the catalyst honeycomb layer are disposed in the can. Measured by the sound wave transmitting means and the sound wave receiving means, the time measuring means for measuring the sound wave propagation time from when the sound wave transmitting means transmits the sound wave until the sound wave receiving means receives the sound wave, and the time measuring means. There is provided a denitration apparatus comprising temperature detection means for calculating a temperature of the space using the sound wave propagation time and detecting blockage of the catalyst honeycomb layer based on the temperature of each of the spaces.

According to such a configuration of the reference example , the sound wave propagation time until the sound wave transmitted from the sound wave transmitter reaches the sound wave receiving unit from the sound wave transmitting unit is measured and calculated using this sound wave propagation time. Temperature information is the temperature of the space in which the sound wave is propagated.
In such a case, the temperature of the space on the front side of the closed catalyst honeycomb layer was compared with the temperature of the space on the downstream side of the closed catalyst honeycomb layer with respect to the flow direction of the combustion exhaust gas. In this case, the latter space has a low temperature because there is a region where there is no (or little) high-temperature gas passage. Thereby, by calculating the temperature of each space and comparing them, the blockage of the catalyst honeycomb layer can be easily detected, and the blocked catalyst honeycomb layer can be easily identified.

The present invention is a denitration apparatus comprising a catalyst honeycomb layer that introduces combustion exhaust gas into a can and removes nitrogen oxides in the combustion exhaust gas by a chemical reaction with a reducing agent such as ammonia sprayed at the can inlet. In the can, the catalyst honeycomb layer disposed in a plurality of stages at a predetermined interval in the flow direction of the combustion exhaust gas, and a sound wave transmitting means disposed in a space formed between the stages of the catalyst honeycomb layer And the sound wave receiving means, the sound wave transmitted by the sound wave transmitting means, and the sound wave that has passed through the catalyst honeycomb layer received by the sound wave receiving means disposed between the sound wave transmitting means and the catalyst honeycomb layer. Attenuation detecting means for detecting attenuation of sound waves and detecting the blockage of the catalyst honeycomb layer based on the attenuation, and the sound wave transmitting means transmit sound waves, and the sound wave receiving means in a common space receive the sound waves. A time measuring means for measuring a sound wave propagation time until the time is calculated, a temperature of the space is calculated using the time measured by the time measuring means, and the catalyst honeycomb layer is blocked based on the temperature of each space. There is provided a denitration apparatus comprising temperature detecting means for detecting.

According to such a configuration, the sonic wave transmitting means and the sonic wave receiving means are arranged in a space formed between the respective stages of the catalyst honeycomb layer arranged in a plurality of stages at a predetermined interval with respect to the flow direction of the combustion exhaust gas. The sound wave transmitted from the sound wave transmitting means is received by the sound wave receiving means disposed with the catalyst honeycomb layer interposed therebetween, and the blockage of the catalyst honeycomb layer is detected based on the attenuation of the sound wave received with the catalyst honeycomb layer interposed therebetween. Is done. Further, the sound wave propagation time until the sound wave transmitted from the sound wave transmitting unit is received by the sound wave receiving unit in the same space as the sound wave transmitting unit is measured, and the temperature information calculated using the sound wave propagation time is The temperature of the space through which the sound wave is propagated.
Thus, when detecting clogging based on the attenuation of sound waves passing through the catalyst honeycomb layer, the clogging of the catalyst honeycomb layer must exist even before dust is deposited on the catalyst honeycomb layer. Can be easily detected. When the temperature of the space before the closed catalyst honeycomb layer is compared with the temperature of the space on the downstream side of the closed catalyst honeycomb layer with respect to the flow direction of the combustion exhaust gas, the latter space , The temperature is low because there is a region where there is no (or few) passage of high-temperature gas. By calculating the temperature in this way, the blockage can be easily detected. Thereby, the blockage of the catalyst honeycomb layer can be detected with high accuracy.

The denitration apparatus includes: a first sound wave receiving unit disposed in a direction facing the sound wave transmitting unit when the cross section of the can facing the flow direction of the combustion exhaust gas in the can is viewed; It is good also as comprising the 2nd sound wave receiving means arrange | positioned at the side surface of the direction which a means faces.
The path between the sound wave transmitting means and the sound wave receiving means will increase, and a wider range of sound waves will be received. Thereby, the blockage condition of the catalyst honeycomb layer can be detected with high accuracy.

The denitration device is disposed in a direction facing the sound wave transmitting means when viewed from a cross section of the can facing the flow direction of the combustion exhaust gas in the can, and is parallel to the position of the sound wave transmitting means. It is good also as providing the 3rd sound wave receiving means which can be moved to.
By making the sound wave receiving means movable, sound waves can be received at different positions by one sound wave transmitting means. Thereby, the number of the sound wave receiving means to arrange | position can be reduced.

It is good also as providing the ceiling acoustic wave transmission means provided in the upstream position in the said can of the said denitration apparatus.
By providing the sound wave transmitting means on the ceiling, the number of sound wave paths to be received by the sound wave receiving means can be increased, so that the accuracy of blockage detection can be improved. In general, the catalyst honeycomb layer (first layer) located on the upstream side in the flow direction of the combustion exhaust gas is more easily clogged than the downstream side. Therefore, in the present invention, the acoustic wave transmitter is provided on the ceiling at the upstream position, and the first layer of the catalyst honeycomb layer having the highest possibility of clogging is intensively inspected.

The present invention relates to a denitration apparatus for a denitration apparatus comprising a catalyst honeycomb layer that introduces combustion exhaust gas into a can and removes nitrogen oxides in the combustion exhaust gas by a chemical reaction with a reducing agent such as ammonia sprayed at the can inlet. In the method, the sound wave is transmitted using the sound wave transmitting means and the sound wave receiving means disposed in the can with the catalyst honeycomb layer disposed in a plurality of stages at a predetermined interval with respect to the flow direction of the combustion exhaust gas. a sound wave transmitting means for transmitting, to detect the attenuation of the sound waves based through the catalyst honeycomb layer and wave received in the wave receiving means, for detecting the clogging of the catalyst honeycomb layer based on the attenuation A denitration method is provided.

A reference example of the present invention is a denitration equipped with a catalyst honeycomb layer that introduces combustion exhaust gas into a can and removes nitrogen oxides in the combustion exhaust gas by chemical reaction with a reducing agent such as ammonia sprayed at the can inlet. In the denitration method of the apparatus, the acoustic wave transmitting means disposed in the space formed between the stages of the catalyst honeycomb layer disposed in the can at a plurality of stages at a predetermined interval with respect to the flow direction of the combustion exhaust gas. And the process of measuring the sound wave propagation time from when the sound wave transmitting means transmits the sound wave until the sound wave receiving means receives the sound wave, and using the measured sound wave propagation time, And a step of calculating a temperature of the space and detecting a blockage of the catalyst honeycomb layer based on the temperature of each space.

The present invention relates to a denitration apparatus for a denitration apparatus comprising a catalyst honeycomb layer that introduces combustion exhaust gas into a can and removes nitrogen oxides in the combustion exhaust gas by a chemical reaction with a reducing agent such as ammonia sprayed at the can inlet. In the method, the acoustic wave transmitting means and the acoustic wave receiver disposed in the space formed between the stages of the catalyst honeycomb layer disposed in the can in a plurality of stages with a predetermined interval in the flow direction of the combustion exhaust gas. And the sound wave transmitted by the sound wave transmitting unit and the sound wave transmitted through the catalyst honeycomb layer received by the sound wave receiving unit disposed between the sound wave transmitting unit and the catalyst honeycomb layer. Attenuation detection process for detecting the attenuation of the catalyst and detecting the blockage of the catalyst honeycomb layer based on the attenuation, and the sound wave transmitting means transmits the sound wave, and the sound wave receiving means in the common space receives the sound wave A time measurement process for measuring the sound wave propagation time at the time, and the temperature of the space is calculated using the time measured by the time measurement process, and the blockage of the catalyst honeycomb layer is detected based on the temperature of each of the spaces A denitration method having a temperature detection process is provided.

  The present invention has an effect that the blockage of the catalyst can be detected with high accuracy.

It is a figure which shows an example of schematic structure of the denitration apparatus which concerns on the 1st Embodiment of this invention. It is an elevation view which shows arrangement | positioning of the catalyst which concerns on 1st Embodiment, an acoustic transmitter, and a receiver. It is a figure which shows an example of arrangement | positioning of the receiver which concerns on the modification 1 of 1st Embodiment. It is a figure which shows an example of arrangement | positioning of the receiver which concerns on the modification 2 of 1st Embodiment. It is a figure which shows an example of arrangement | positioning of the acoustic transmitter which concerns on the modification 3 of 1st Embodiment. It is a figure which shows an example of schematic structure of the denitration apparatus which concerns on the 2nd Embodiment of this invention. It is an elevation view which shows arrangement | positioning of the catalyst which concerns on 2nd Embodiment, an acoustic transmitter, and a receiver.

Hereinafter, an embodiment of a denitration apparatus according to the present invention will be described with reference to the drawings.
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a diagram illustrating a schematic configuration of a denitration apparatus 100 according to the first embodiment. As shown in FIG. 1, the denitration apparatus 100 includes an acoustic transmitter (sound transmitting means) Sn, Sn ′ (n is a number indicating a space in which the acoustic transmitter is disposed, and n = 1, 2, 3 and 4) and receivers (sound wave receiving means) Rn, Rn ′ (n is a number indicating a space in which the receivers are arranged, n = 1, 2, 3, 4), and frequency analyzer 1 , An amplifier 2, an oscillator 3, a storage unit 5, an attenuation detection unit (attenuation detection means) 6, and catalysts (catalyst honeycomb layers) 12a, 12b, and 12c. Unless otherwise specified, the catalyst is described as catalyst 12, the acoustic transmitter is described as acoustic transmitter S, and the receiver is described as receiver R.

In the denitration apparatus 100, the duct 4 is connected to the inflow side of the combustion exhaust gas. The denitration apparatus 100 introduces combustion exhaust gas into the can 11 from the upstream side through the duct 4, and nitrogen oxides in the combustion exhaust gas by a chemical reaction with a reducing agent such as ammonia sprayed at the catalyst inlet at the catalyst 12. This is a device for removing (NOx). Further, the catalyst 12 is arranged in a plurality of stages (three stages in the example of FIG. 1) with a predetermined space (interval) 13 in the can 11.
In this embodiment, two acoustic transmitters S and two receivers R are provided in each space 13, and the catalyst 12 is arranged in three stages, so that four spaces 13 are provided. I will explain that. The number of acoustic transmitters S and receivers R provided in each space 13 is not limited to this, and no upper limit is particularly provided. In the following description, the space is indicated as space 13 unless otherwise specified, but is indicated as spaces 13a, b, c, d when the order from the top is indicated.

The oscillator 3 repeatedly generates a sound wave having a predetermined frequency, and emits the sound wave to the space 13 via the acoustic transmitter S. For example, the oscillator 3 uses F ₁ and F ₁ ′ as frequencies of sound waves transmitted from the acoustic transmitters S ₁ and S ₁ ′, and sets a frequency of sound waves transmitted from the acoustic transmitters S ₂ and S ₂ ′. The frequency of the sound wave to be transmitted is made different for each acoustic transmitter S arranged at different positions, such as F ₂ and F ₂ ′.
The amplifier 2 amplifies the sound wave output from the oscillator 3 and outputs the amplified sound wave to the acoustic transmitter S. The amplifier 2 amplifies the sound wave acquired from the receiver R and outputs the amplified sound wave to the frequency analyzer 1.
The frequency analyzer 1 analyzes the frequency of the sound wave received by the receiver R and outputs the analysis result to the attenuation detector 6.

In the storage unit 5, attenuation information measured from the sound wave transmitted from the acoustic wave transmitter S and the sound wave received by the wave receiver R when the catalyst 12 is not blocked is normal. Stored. For example, when no blockage occurs, the sound waves transmitted from the acoustic wave transmitter S _{1 in} FIG. 1 are received by the wave receivers R ₂ , R ₂ ′, R ₃ , R ₃ with the catalyst 12 interposed therebetween. The attenuation state is measured based on the sound wave received at each of ', R ₄ , R ₄ ', and the measurement result is stored in the storage unit 5. Further, the same attenuation measurement is performed on the sound waves output from all the acoustic transmitters S, and the measurement results are stored respectively.

  The attenuation detector 6 detects the attenuation of the sound wave based on the sound wave transmitted by the acoustic transmitter S and the sound wave received by the receiver R, and detects the blockage of the catalyst 12 based on the attenuation. Specifically, the attenuation detection unit 6 identifies the transmission source acoustic transmitter S based on the frequency analysis result acquired from the frequency analyzer 1 and also identifies based on the information stored in the storage unit 5. The information on the normal attenuation of the sound wave from the acoustic transmitter S is compared with the information on the attenuation of the sound wave received by the receiver R, and when the comparison result is a predetermined value or more, the catalyst 12 It is detected that the blockage has occurred.

  Two acoustic transmitters S are provided between the respective catalysts 12 and are arranged at two different positions in the horizontal direction. In the present embodiment, two acoustic transmitters S are provided in each of the first to fourth four spaces 13. Moreover, although the acoustic transmitter S uses the acoustic wave transmitter installed in order to detect obstruction | occlusion, it is not limited to this. For example, an acoustic removal device provided for a removal device that removes powder that accumulates in the catalyst the force of pressure fluctuation caused by sound propagation may be used.

The wave receivers R are provided between the catalysts 12 and are arranged in a direction facing the acoustic wave transmitter S, and two are arranged at different positions in the horizontal direction.
In the present embodiment, the acoustic transmitter S and the receiver R are described as being non-directional, but the present invention is not limited to this. For example, directional ones may be used. For example, when using directional receivers, use transmitters as many as the number of receivers, or use a transmitter having a mechanism for changing the angle of sound waves to be transmitted. It is desirable.

FIG. 2 is an example of an elevation view of the first catalyst 12a as viewed from above. 2, acoustic wave transmitter _S 1, 'wave receiver in a facing position _R 2, _{R 2' S 1} is disposed, the acoustic transmitters _S 1 disposed in the first space 13a, The state is shown in which the sound waves sent from S ₁ ′ are received by the receivers R ₂ and R ₂ ′ arranged in the second space 13b with the catalyst 12a interposed therebetween. Further, the fact that the catalyst 12a in FIG. 2 is indicated by a lattice pattern indicates that the catalyst 12 has a honeycomb shape.
Here, as shown in FIG. 2, in the catalyst 12a, the sound waves arriving from S ₁ to R _2, and from S ₁ attenuation of the sound waves reaching the R _{2 'is} the normal, which is stored in the storage unit 5 If greater than the attenuation caused, is estimated to occlusion X on the path of the wave receiver R _{2 'from} the acoustic wave transmitter S ₁ from the path and on the acoustic wave transmitter S ₁ of receivers R ₂ is present.

Further, the blockage of the catalyst 12 may be determined using a plurality of paths. For example, in FIG. 1, the wave receiver _{R 3,} acoustic wave transmitter passing the sound waves from the acoustic wave transmitter _{S 1} passing through the first catalyst 12a and the second catalyst 12b, a second catalyst 12b It will be described that receives the sound waves of the two paths of the sound waves from S _2. When the attenuation is greatly estimated in the path of S ₁ -R _{3 and} the amount of attenuation is within the range where the attenuation is determined to be normal in the path of S ₂ -R ₃ , the first catalyst 12 a is blocked. Can be determined. Thus, the blockage can be determined also by the attenuation amounts of the plurality of paths.

Next, the operation of the denitration apparatus 100 according to the present embodiment will be described with reference to FIG.
Combustion exhaust gas is introduced into the can 11 from the duct 4 on the upstream side of the can 11, and a reducing agent such as ammonia is sprayed at the inlet of the can 11, and combustion exhaust gas is generated by a chemical reaction generated when passing through the catalysts 12 a, 12 b, and 12 c. The nitrogen oxide (NOx) in the inside is removed. In this process, the case where the combustion exhaust gas contains soot and the first catalyst 12a is clogged is taken as an example, and the acoustic transmitters S ₁ and S ₁ ′ and the receivers R ₂ and R ₂ ′. This will be explained with a focus on the above.

Sonic 'different frequencies _F 1, _{F 1} for each of the' acoustic transmitters _S 1, _{S 1} is output from the oscillator 3 is amplified by the amplifier 2, emitted from the acoustic wave transmitter _S 1, _{S 1} ' Is done. Sound waves transmitted from the acoustic transmitters S ₁ and S ₁ ′ are received by the receivers R ₂ and R ₂ ′, amplified by the amplifier 2, and then output to the frequency analyzer 1. In the frequency analyzer 1, the acoustic transmitter S of the sound wave transmission source is specified as the acoustic transmitters S ₁ and S ₁ ′ based on the received sound wave frequencies F ₁ and F ₁ ′. Information on the identified acoustic transmitter S and information on the received sound wave are output to the attenuation detector 6.

In the attenuation detecting unit 6, the wave receiver path between the acoustic wave transmitter S ₁ and wave receiver R _2, acoustic wave transmitter S _{1 'and} the path of the receivers R _2, acoustic wave transmitter S _1' and Attenuation of sound waves of the path of R ₂ , the path of the acoustic transmitter S ₁ ′ and the path of the receiver R ₂ ′, and when the four paths stored in the storage unit 5 are normal (clogged by the catalyst) Is compared with the amount of attenuation. As a result of comparison, when the attenuation amount of the route S ₁ -R ₂ and the route S ₁ -R ₂ ′ is larger than the normal amount, the route S ₁ -R ₂ and the route S ₁ -R ₂ ′ are on the route. In the region X, it is detected that the catalyst 12a is blocked. As a result of comparison, when the attenuation amount of the path S ₁ ′ -R ₂ and the path S ₁ ′ -R ₂ ′ is within a range that is considered to be normal, the path S ₁ ′ -R ₂ and the path S the on a path of _{1 '-R 2'} is determined that there is no blockage of the catalyst 12a.

  As described above, according to the denitration apparatus 100 and the denitration method according to the present embodiment, the acoustic transmission disposed with the catalyst 12 disposed in a plurality of stages at a predetermined interval with respect to the flow direction of the combustion exhaust gas. In the waver S and the wave receiver R, when the sound wave transmitted from the acoustic wave transmitter S passes through the catalyst 12 and is received by the wave receiver R, the transmitted sound wave and the received sound wave The sound wave attenuation is detected, and the blockage of the catalyst 12 is detected based on the sound wave attenuation. As described above, since the blockage is detected based on the attenuation of the sound wave passing through the catalyst 12, the blockage of the catalyst 12 is blocked when the attenuation amount of the sound wave is larger than the attenuation when the catalyst 12 is not blocked. Detect that there is. Thereby, even before dust is deposited on the catalyst 12, even when the catalyst is blocked at an initial stage, the blocking of the catalyst 12 can be easily detected. Moreover, since the blockage state can be grasped according to the amount of attenuation, the number of prepared honeycombs for replacement can be estimated, and the region to be inspected can be narrowed down.

[Modification 1]
In addition, in this embodiment, although the arrangement position of the receiver R was demonstrated as arrange | positioning in the position which faces the acoustic transmitter S, it is not limited to this. For example, as shown in FIG. 3, the first receivers (first sound wave receiving means) R ₂ and R ₂ ′ disposed at the facing positions and the side surfaces in the direction facing the acoustic transmitter are disposed. Second receivers (second sound wave receiving means) R _{2 ″} , R ₂ ″ ″ are provided. In this manner, by arranging the receiver also on the side surface facing the acoustic transmitter, it is possible to detect the blockage of the region outside the sound wave path in the facing direction. Thereby, the area | region which can detect obstruction | occlusion can be expanded, and the precision of obstruction | occlusion detection can be improved.

[Modification 2]
Alternatively, for example, as shown in FIG. 4, the wave receiver (third sound wave receiving means) is arranged in a direction facing the acoustic wave transmitter S and moves in parallel with the position of the acoustic wave transmitter S. It may be possible. Thus, by making it movable, the number of receivers R can be reduced, and the installation cost of the receivers R can be reduced.

[Modification 3]
Moreover, although the position of the acoustic transmitter S was supposed to be provided in each space 13 shown in FIG. 1, it is not limited to this. For example, as shown in FIG. 5, a ceiling acoustic transmitter (ceiling acoustic wave transmission means) S ₀ may be installed on the ceiling portion. For example, the catalyst honeycomb layer (first layer) located on the upstream side in the flow direction of the combustion exhaust gas is more easily clogged than the downstream side, so that the acoustic transmitter S ₀ is provided on the ceiling at the upstream position. . Thereby, the first layer of the catalyst honeycomb layer having the highest possibility of clogging can be intensively inspected. Thus, by providing the acoustic transmitter S on the ceiling, the number of sound wave paths received by the receiver R can be increased, so that the accuracy of blockage detection can be improved.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS.
The difference between the denitration apparatus 100 ′ of the present embodiment and the first embodiment is that instead of obtaining the clogging of the catalyst 12 based on the attenuation of the sound wave passing through the catalyst 12 in the first embodiment, combustion is performed. The point is that the blockage of the catalyst 12 is determined based on the temperature in each space 13 in the process of the exhaust gas passing through the catalyst 12. Hereinafter, regarding the denitration apparatus 100 ′ of the present embodiment, description of points that are common to the first embodiment will be omitted, and different points will be mainly described.

  FIG. 6 is a diagram showing a schematic configuration of a denitration apparatus 100 ′ of the second embodiment. As shown in FIG. 6, the denitration apparatus 100 ′ includes acoustic transmitters Sn and Sn ′ (n is a number indicating a space in which the acoustic transmitter is disposed, and n = 1, 2, 3, 4). And receivers Rn, Rn ′ (n is a number indicating a space in which the receivers are arranged, n = 1, 2, 3, 4), a time measuring unit (time measuring means) 8 and a temperature detecting unit. (Temperature detection means) 9, amplifier 2, oscillator 3, and catalysts (catalyst honeycomb layers) 12 a, 12 b, 12 c are provided. Unless otherwise specified, the catalyst is described as catalyst 12, the acoustic transmitter is described as acoustic transmitter S, and the receiver is described as receiver R.

The receiver R receives sound waves transmitted from the acoustic transmitter S in the same space 13. FIG. 7 shows a state where sound waves transmitted from the acoustic transmitters S ₂ and S ₂ ′ in the lower space 13 of the first catalyst 12 a are received by the receivers R ₂ and R ₂ ′. Has been.

The time measuring unit 8 measures the propagation time t of the sound wave from when the acoustic transmitter S transmits the sound wave to when the receiver R receives the sound wave, and outputs it to the temperature detecting unit 9. Specifically, the time measuring unit 8 includes a voltage measuring device 7, and the voltage measuring device 7 outputs the sound pressure of the sound wave received by the receiver R as a voltage value. The time measuring unit 8 has information on the voltage value in the normal state without sound waves, and the timing at which the voltage value output by the voltage measuring instrument 7 is larger than the voltage value in the normal state is sound waves. The sound wave propagation time t is measured based on the time difference between this reception time and the transmission time at which the sound wave is transmitted from the acoustic transmitter S.
The temperature detection unit 9 calculates the temperature of the space 13 using the propagation time t measured by the time measurement unit 8, and detects the blockage of the catalyst 12 based on the temperature of each space 13. Hereinafter, a method for calculating the temperature of the space 13 will be described. The propagation time t in a sound wave path that does not pass through the catalyst 12 (for example, the acoustic transmitter S ₂ to the receiver R ₂ , the acoustic transmitter S ₂ to the receiver R ₂ ′, etc.) is calculated by the equation (1). Is done. Here, L represents the width of the denitration device, and c represents the speed of sound.

  The speed of sound c is expressed as shown in equation (2), where γ is specific heat, R is a gas constant, and T is absolute temperature [K]. Therefore, equation (1) is expressed as equation (3). It is. Tc is an average temperature [° C.] between the acoustic transmitter S and the receiver R.

  The presence or absence of blockage is determined by comparing the temperature Tc of each space 13 calculated by the above method with the temperature Tc ′ of the upper space 13. For example, when the first catalyst 12a is clogged, the temperature Tc of the second space 13 is estimated to be lower than the temperature Tc ′ of the first space 13, and thus the first space 13 is compared with the temperature of the second space to determine whether or not the first catalyst 12a is blocked.

  In the present embodiment, the presence or absence of blockage is determined by comparing with the temperature of the upper space 13, but the present invention is not limited to this. For example, it is good also as providing the storage part which stores the normal temperature in which the blockage has not arisen. In this case, the receiving unit disposed in the same space 13 as the timing at which the sound wave is transmitted from the acoustic transmitter S when the catalyst 12 is in a normal state where the catalyst 12 is not clogged. Based on the propagation time t ′ measured from the timing at which the sound wave is received at R, the temperature information at the normal time is calculated, and the temperature information is stored. Thus, by storing the temperature of the space 13 when the storage unit is not closed, the presence or absence of the blockage can be easily determined.

Next, the operation of the denitration apparatus 100 ′ according to the present embodiment will be described with reference to FIGS. 6 and 7.
Here, combustion exhaust gas is introduced into the can 11 from the duct 4 on the upstream side of the can 11, and a chemical reaction that occurs when a reducing agent such as ammonia is sprayed at the inlet of the can 11 and passes through the catalysts 12 a, 12 b, and 12 c. As a result, nitrogen oxides (NOx) in the combustion exhaust gas are removed. In this process, the case where the combustion exhaust gas contains soot and the first catalyst 12a is clogged is taken as an example, and the acoustic wave transmitter S that measures the temperature of the combustion exhaust gas passing through the first catalyst 12a. ₂ and S ₂ ′ and the receivers R ₂ and R ₂ ′ will be described.

Acoustic transmitters S _2, S 2 _'sound waves having different frequencies for each of the output from the oscillator 3 is amplified by the amplifier 2, an acoustic wave transmitter S _2, S _2' is released from the. The sound waves transmitted from the acoustic transmitters S ₂ and S ₂ ′ are received by the receivers R ₂ and R ₂ ′, amplified by the amplifier 2, and then input to the voltage measuring device 7 of the time measuring unit 8. The In the voltage measuring device 7, the sound wave is transmitted based on the voltage of the sound wave transmitted from the acoustic transmitters S ₂ and S ₂ ′ and the voltage of the sound wave received from the wave receivers R ₂ and R ₂ ′. The propagation time t of the sound wave from reception until reception is detected. When the propagation time t is detected, the temperature Tc of the space 13 in which the sound wave is detected is calculated based on the above-described equation (4). The calculated temperature Tc is compared with the temperature Tc ′ of the upper space 13 of the first catalyst 12a. When Tc is lower than Tc ′ by a predetermined value as a result of comparison, it is determined that the first catalyst 12a is clogged, and Tc has a temperature difference lower than the predetermined value by less than Tc ′. Is determined not to block the first catalyst 12a. Similarly, the comparison between the temperature of the second space 13b and the temperature of the third space 13c and the comparison of the temperature of the third space 13c and the temperature of the fourth space 13d are continuously performed.

  As described above, according to the denitration apparatus 100 ′ and the denitration method according to the present embodiment, the sound wave transmitted from the acoustic transmitter S until the acoustic wave reaches the receiver R from the acoustic transmitter S. The sound wave propagation time t is measured, and information on the temperature Tc calculated using the sound wave propagation time t is the temperature of the space 13 where the sound wave is propagated. In such a case, the temperature Tc ′ of the space 13 on the front side of the closed catalyst 12 and the temperature Tc of the space 13 on the downstream side of the closed catalyst 12 with respect to the flow direction of the combustion exhaust gas, Are compared, the latter space has a low temperature because there is no (or little) passage of high-temperature gas. Thus, the blockage of the catalyst 12 can be easily detected by calculating the temperature Tc of each space 13 and comparing it with the temperature Tc ′ of the upper space 13 respectively.

  Further, the denitration apparatus 100 ′ according to the present embodiment may be combined with the denitration apparatus 100 of the first embodiment described above. Specifically, a mechanism (frequency analyzer) that calculates attenuation of sound waves and a mechanism (time measurement unit and temperature detection unit) that calculate the temperature of the space are provided after the receiver R. Thus, by detecting the blockage by combining the attenuation of the sound wave and the temperature of the space, the accuracy of narrowing the blockage region can be improved.

Sn, Sn ′ (n = 1 to 4) Acoustic transmitters Rn, Rn ′ (n = 1 to 4) Receiver L Denitration device width X Closure 4 Duct 5 Storage 6 Attenuation detector 7 Voltage measuring device 8 Time measurement unit 9 Temperature detection unit 12a, 12b, 12c Catalyst (catalyst honeycomb layer)
13a, 13b, 13c, 13d Space 100, 100 ′ Denitration device

Claims (8)

In a denitration apparatus including a catalyst honeycomb layer that introduces combustion exhaust gas into a can and removes nitrogen oxides in the combustion exhaust gas by a chemical reaction with a reducing agent such as ammonia sprayed at the can inlet,
In the can, the catalyst honeycomb layer disposed in a plurality of stages at a predetermined interval with respect to the flow direction of the combustion exhaust gas,
A sound wave transmitting means and a sound wave receiving means disposed with the catalyst honeycomb layer interposed therebetween,
A sound wave the wave transmitting means for transmitting said passed through the catalyst honeycomb layer detects the attenuation of the sound waves based on the sound waves received by the wave receiving means, the clogging of the catalyst honeycomb layer based on the attenuation A denitration device comprising attenuation detection means for detecting.   2. The denitration apparatus according to claim 1, wherein the sound wave receiving unit receives sound waves transmitted from the sound wave transmitting unit provided at a plurality of different positions and passed through the common catalyst honeycomb layer. In a denitration apparatus including a catalyst honeycomb layer that introduces combustion exhaust gas into a can and removes nitrogen oxides in the combustion exhaust gas by a chemical reaction with a reducing agent such as ammonia sprayed at the can inlet,
In the can, the catalyst honeycomb layer disposed in a plurality of stages at a predetermined interval with respect to the flow direction of the combustion exhaust gas,
A sound wave transmitting means and a sound wave receiving means arranged in a space formed between the steps of the catalyst honeycomb layer;
Attenuation of the sound wave is detected based on the sound wave transmitted by the sound wave transmitting unit and the sound wave that has passed through the catalyst honeycomb layer received by the sound wave receiving unit disposed between the sound wave transmitting unit and the catalyst honeycomb layer. Attenuation detection means for detecting blockage of the catalyst honeycomb layer based on the attenuation;
A time measuring means for measuring a sound wave propagation time until the sound wave transmitting means transmits a sound wave and the sound wave receiving means in a common space receives the sound wave; and
A denitration apparatus comprising: a temperature detection unit that calculates a temperature of the space using the time measured by the time measurement unit and detects blockage of the catalyst honeycomb layer based on the temperature of each space. When looking at the cross section of the can facing the flow direction of the combustion exhaust gas in the can,
First sound wave receiving means disposed in a facing direction of the sound wave transmitting means;
The denitration apparatus according to any one of claims 1 to 3, further comprising a second sound wave receiving unit disposed on a side surface of the sound wave transmitting unit in a facing direction. When looking at the cross section of the can facing the flow direction of the combustion exhaust gas in the can,
The denitration apparatus according to any one of claims 1 to 4, further comprising a third sound wave receiving unit that is disposed in a direction facing the sound wave transmitting unit and is movable in parallel with a position of the sound wave transmitting unit. .   The denitration device according to any one of claims 1 to 5, further comprising a ceiling acoustic wave transmission unit provided at an upstream position in the can. In the denitration method of the denitration apparatus comprising the catalyst honeycomb layer that introduces the combustion exhaust gas into the can and removes nitrogen oxides in the combustion exhaust gas by a chemical reaction with a reducing agent such as ammonia sprayed at the can inlet,
In the can, using a sound wave transmitting means and a sound wave receiving means that are disposed across the catalyst honeycomb layer disposed in a plurality of stages at a predetermined interval with respect to the flow direction of the combustion exhaust gas,
A sound wave the wave transmitting means for transmitting said passed through the catalyst honeycomb layer detects the attenuation of the sound waves based on the sound waves received by the wave receiving means, the clogging of the catalyst honeycomb layer based on the attenuation Denitration method to detect. In the denitration method of the denitration apparatus comprising the catalyst honeycomb layer that introduces the combustion exhaust gas into the can and removes nitrogen oxides in the combustion exhaust gas by a chemical reaction with a reducing agent such as ammonia sprayed at the can inlet,
In the can, using acoustic wave transmitting means and acoustic wave receiving means arranged in a space formed between the stages of the catalyst honeycomb layer arranged in a plurality of stages at a predetermined interval in the flow direction of the combustion exhaust gas And
Attenuation of the sound wave is detected based on the sound wave transmitted by the sound wave transmitting unit and the sound wave that has passed through the catalyst honeycomb layer received by the sound wave receiving unit disposed between the sound wave transmitting unit and the catalyst honeycomb layer. An attenuation detection process for detecting blockage of the catalyst honeycomb layer based on the attenuation;
A time measurement process of measuring a sound wave propagation time until the sound wave transmitting unit transmits a sound wave and the sound wave receiving unit in a common space receives the sound wave;
A denitration method comprising: a temperature detection step of calculating a temperature of the space using the time measured in the time measurement step, and detecting blockage of the catalyst honeycomb layer based on the temperature of each of the spaces.

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